Showing posts with label General Principles. Show all posts
Showing posts with label General Principles. Show all posts

Thursday, September 19, 2019

General Mammalian Patterns, esp., Patterns of Group-living Species [compiled by Clara B. Jones]

General Mammalian Patterns [?--in no particular order] with an emphasis on Group-living taxa, especially, Social Biology & Behavioral Ecology--also see Twitter @cbjones1943... Conceptual Framework... 

FIRST PRINCIPLES OF BEHAVIORAL ECOLOGY:: E[nergy]: Acquisition->Consumption->Allocation====> Worker &/or Reproductive &/or Dependent...(Males, T[ime] Minimizers; Females, E[nergy] Maximizers)


Mammals: Anisogamy-->Sexually-Antagonistic Selection-->Sexual Conflict-->Differential T-E investment, including, Life History (males, time-minimizers; females, energy-maximizers)-->Sexual Dimorphism, inc, Body Size...constrained by dispersion of limiting resources [especially, food for females, mates for males]--that may or may not not favor group-living...[apply, for example, to evolution of male Alternative Reproductive Behaviors (ARBs) & female "counterstrategies"]...


For analysis, and where data permit, we will separate comments for large [>100 kg] & small mammals--as suggested in literature, e.g., https://pdfs.semanticscholar.org/3281/ad106c0d6a9fdc831b7725dc5d3460222136.pdf

Terminology & Context: Terminology in the field of Social Biology, here, related to Social Evolution, is not standardized ... for example, WD Hamilton & Stu A. West, define "social" in different ways, the former limiting use of "social" to Cooperation & Altrusim, the two [of four] categories of behavior [Selfish, Cooperation, Altruism, Spite] in which Recipient gains "fitness" benefits ... West, on the other hand, defines "social" as any interindividual interaction where either or both interactants benefit reproductively ... recall that "interdependence" is a necessary precursor to Cooperation, while Cooperation is a necessary precursor to the evolution of Complex Sociality ... here, I am thinking of Cooperation as per Hamilton--an interindividual interaction in which both interactants benefit in "fitness"  ... related to the Major Transitions Approach, Complex Sociality [division-of-labor (cooperation between specialists); task, role, &/or morphological specialization] is, particularly, problematic, it seems to me ... if we view specialization along a continuum, say, from feeding specialization to DoL to reproductive DoL with "totipotent" workers or "helpers" to reproductive DoL with more or less "sterile castes" [social insect workers], do we accept the typical usage whereby Advanced Eusocial taxa are the most "complex" societies [the "pinnacle" of sociality as per Wilson (1971)]? ... though many Social Scientists would claim that interindividual interactions in humans represent the "pinnacle" of Complex Sociality, expert consensus among Social Biologists (e.g., B Crespi 2014) have concluded that humans cannot be classified, Eusocial, because this species does not display "reproductive division-of-labor" ... it is worth pointing out that the wide variety of human reproductive groups have not been systematically described, classified, or diagnosed, including, analysis of populations in which more than one architecture is found, such as all modern nation-states [e.g., monogamy, polygamy, promiscuity, etc.] ... whether & how & why these various conformations interact over Time & Space remains to be determined ... it is assumed that 1st Principles [T, E, acquisition, consumption, allocation] relative to abiotic [e.g., climate] & biotic [e.g., food dispersion; breeding sites] environmental regimes, as well as, constraints of limiting resources, as well as, species-typical female traits, always apply ...


1... most Mammals are "sexually segregated" [sometimes termed, "solitary" in the literature]; however, aggregations [temporary clumping of animals] may occur around clumped, limiting resources, especially, food [as, white-tailed deer may do in Spring when food is abundant & clumped]; other aggregations may form when animals migrate from one feeding &/or breeding ground to another; the term "herds" often refers to an aggregation ... the term, "group," is reserved for a reproductive unit ... Hamilton's Rule [rb - c>0 ----> rb > c] is widely accepted as a general formulation of Social Evolution ... according to Hamilton (1964), "social" behavior is limited to Cooperation & Altruism--the only conformations of interindividual interactions [Selfish, Cooperation, Altruism, Spite] whereby Recipient gains in "fitness" ... this definition of "social" should be derivable from Hamilton's equations ...



2... Several authors have claimed that large mammals have, cet. par., generalized phenotypes (e.g., Eisenberg 1981), presumably, related to evolution in heterogeneous regimes ["environmental grain" theory proposed by Richard Levins 1968. Wilson '75 posits that [1] phenotypic flexibility/plasticity is a general feature of social evolution of large mammals [n.b., the evolution of "learning" should be discussed here, including, the evolution of "social" learning requisite to Culture]; however, generalized phenotypes may represent [2] "canalization." Whether [1] or [2] is an effect of temporal variability & "grain" will depend upon patterns of variability [e.g., rainfall, hurricanes] relative to Generation Time [Is the environment trackable?] . For all of the topics in #2, you might want to take a look at my 2012 Springer Brief. Furthermore, to the extent that mammals exhibit generalized phenotypes, this trait would be expected to inhibit evolution of specialized morphologies, such as, morphologically distinct castes. See sections on generalized phenotypes in Eisenberg (1981).

3... Mammalian phenotypes are usually generalized [see Eisenberg op. cit.] ... the evolution of Complex Sociality requires Specialization [division-of-labor; task, role, &/or morphological specialization]; Interdependence [among interacting group members] is a necessary precursor to the evolution of Cooperation ... since Cooperation is a necessary precursor to the evolution of Complex Sociality, specialization must evolve at some point during the Cooperation "grade" ... Hamilton (op. cit.) classifies "cooperation" as an interaction in which both Actor & Recipient benefit reproductively ... as a significant aside, in taxonomic studies, "specialization" is used to diagnose "primitive"/"ancestral" from "derived"/recent characters, where "specialization" is a criterion for "derived" classification ...

4... depending upon environmental regime, an advantage of a generalized phenotype is promotion of phenotypic flexibility [reversible response] &/or phenotypic plasticity [irreversible response]--responses that are usually condition-, context-, situation-dependent ... in extreme &/or highly time-varying environments, responses may be "decided" statistically or probabilistically, even under Hamilton's Rule [op. cit.; often termed "kin selection"] ... it is worth pointing out that a] Hamilton's Rule [rb - c >0 ----> rb>c] does not predict that it is always beneficial to assist the reproduction of kin] the evolution of sociality does not necessarily require individual recognition, e.g., "greenbeards" may operate or "decisions" may be based on probabilities or likelihoods ...

5... the observation that most mammalian phenotypes are generalized is usually attributed to evolution in time-varying environments ... because most mammalian phenotypes are generalized & because Complex Sociality requires the evolution of specialization, it is expected that Complex Sociality, &, possibly, Cooperation, would be uncommon in the Class & in other taxa with generalized phenotypes ... except for cooperatively-breeding mammals & the [eu]social mole rats, [reproductive] division-of-labor [cooperation between specialists] has not been described to date in mammals; task, role, & morphological specialization are described so far only for the social [eusocial] mole rats ... several other species of mammals are potential candidates for specialization [see David Macdonald's edited reviews of Mammal Orders ... in humans, whose phenotypes are generalized in the mammalian mode, the evolution of learning mechanisms permits [learned] specializations such as division-of-labor and task, role specialization ... learning may have evolved in mammals with generalized phenotypes, in part, to minimize the costs of solitary living and maximize the benefits of group-living ... the question of whether morphological specialization has evolved in humans has not, to my knowledge, been systematically studied in humans; however, Race [ecotype] may be a candidate for morphological specialization in Homo sapiens ...

6... since most mammals' phenotypes are generalized, the evolution of Complex Sociality [&, possibly, Cooperation] is expected to be severely constrained in the Class ... on the other hand, some mammal species display specialized phenotypes, & many species display both generalized and specialized traits ... selection may favor some characters [e.g., Learning; phenotypic flexibility (reversible) & phenotypic plasticity (irreversible)] because they minimize the costs &/or maximize the benefits of generalization &/or specialization ... thinking in terms of differential costs & benefits [to "fitness"], research has led to the conclusion that specialists are good competitors but vulnerable to extinction while generalists are poor competitors but comparatively less vulnerable to extinction ...



7... Selander & Kaufman (1973) and others [see paper linked in #1 above] argue that large mammals have higher tolerance for genetic monomorphism. 

8... The basis for Social Evolution in mammals is "milk", according to EO Wilson [1975, Sociobiology, Belknap: HUP] n.b. a number of authors claim that the basis for Social Evolution in mammals is the primitively [non-cooperative, non-altruistic] communal female group leading to polygyny [c.f. Wittenberger 1980]. The basis of Wilson's point, however, is that Mammal females are obligate caretakers of young, predisposing them to certain life-history trajectories, including, probably, receiving help, all limited by energetics. Recall the litany that females are "energy-maximizers," males, "time-minimizers." Some female mammals, extend maternal care [&, often, lifespan], a trait that will retard the evolution of "complex" sociality [specialization, eusociality] because extended maternal care prevents the evolution of reduced maternal care and the evolution of the de-coupling of Survival and Fecundity. Importantly, in humans, social insects, & "primitively" eusocial mole-rats [& "cooperatively-breeding" mammals?], an apparently rare life-history strategy is found [among females] whereby extended lifespan [a "slow" life-history trait] is combined with a high reproductive rate [a "fast" life-history trait]. In humans, however, extended lifespan is, apparently, combined with increased investment in maternal care; while, in social insects, social mole-rats, & "cooperatively-breeding" mammals [?],  extended lifespan in associated with reduced maternal care--a necessary, though, not sufficient, condition for the evolution of higher "grades" of sociality [specialization, eusociality, genotypic altruism]. Further, reduced maternal care is a necessary trait associated with decoupling of Survival & Fecundity.

9... According to Wilson (1975, p 379), the four "pinnacles" of social evolution are: the colonial invertebrates [e.g., corals, bryozoans], the social insects, the non-human mammals, & humans]. n.b. reflective of a "major transitions" approach to the Tree of Life

10... Traits of the non-human mammals: aggressiveness & discord carried further in vertebrate, including, mammal, societies than in social insects...selfishness rules inter-individual interactions...no sterile castes [though reproduction may be suppressed chemically or by "choice"]...acts of altruism infrequent and usually directed toward kin, especially, offspring...cooperation usually rudimentary; though inequity & hierarchy virtually ubiquitous [wherever there is division of labor there will be inequity]...by human standards, some acts "brutal" [e.g., treatment of infirm & dying]...mostly after Wilson '75, p 380

11... Human social traits: humans remain "essentially vertebrate" in their social structure, but more "complex," not by reduction of selfishness but by evolution of intelligence and language [relate to phenotypic plasticity; learning, including, social learning (cultural mechanism); social parasitism; persuasion; manipulation; exploitation, etc]...elaboration of kin relations [cost-benefit]...human societies "approach" levels of cooperation in insect societies & far exceed social insect societies in communication...mostly after Wilson '75, p 380

12... Most "interesting" mammal orders: rodents, artiodactyls, primates, marsupials--"control group" for Class after Wilson '75 & Eisenberg '81 [social biology of largest mammal orders--bats, rodents--virtually unknown as of 1975]...mostly after Wilson '75, p 468 x

13... Traits labile [e.g., mode of intrasexual cooperation, degree of cohesion, openness of societies (c.f. "open" vs. "closed" groups)]. Many forms of interaction change seasonally, & patterns differ at species level. [after Wilson '75]

14... Phylogenetically, more primitive living marsupials and insectivores tend to be solitary. Species that forage nocturnally or underground are, also, mainly solitary. Eisenberg [1981] & Wilson [1975] posit that marsupials are the only "control group" we have for Class Mammalia as a whole.

15... As a rule, the most complex social systems within each Order occur in the physically largest numbers...true of marsupials, rodents, ungulates, carnivores, and primates [Why? maybe because diurnal and because of large brains (intelligence?)? Wilson '75 Also, refer to J.H. Crook's work with weaver birds and other work in Behavioral Ecology: need to evaluate dispersion (distribution and abundance in time and space) of limiting resources relative to behavior & social biology].

16... Species adapted to life in open environments more likely to be social. Rodents known to form coteries of mixed sexes are all inhabitants of grasslands. Ungulates--great herds predominantly found in grasslands and on savannas, though herds mostly loosely structured--but see, horses, mountain sheep, elephants, and a few others [zebras?] Wilson '75

17... The structure of mammal [vertebrate?] groups is thought to result from the tendency of females to select rich patches of food and that of males to select large aggregations of females. Because patch richness and the consequent number [and quality] of females [female group size] is expected to vary, the relative reproductive success [RRS] of females may, also, vary over time and space. See the following paper, for example:

http://eprints.uberibz.org/1173/1/jones_2008.pdf

Also, see:

Jones, CB (March, 1996) Relative reproductive success [RRS] in the mantled howler monkey: implications for conservation. Neotropical Primates 4(1), pp 21-23.

18... Chapters on Mammals in Rubenstein & Abbott (2017), may not be very useful for treatments of general patterns of Social Biology in Mammals; however, see stimulating final, summary chapter in this ambitious edited volume.

19. IMO, the chapters in Wilson (1975) on non-human primates and on humans are not very useful for identifying patterns across the Primates, in Homo sapiens, across Mammals [or, across vertebrates].

20... Tim Clutton-Brock's text, Mammal Societies, not very useful for identifying general patterns of Social Biology in Mammals. This book is not a Synthesis for the Mammals in the way that Wilson's [1971], Insect Societies, is a Synthesis for the Social Insects--even though TC-B titles his book, Mammal Societies. This book is a highly selective literature review. See, however, the useful table of contents & #generateideas. re: sub-eusocial insects--their traits & trends--see James Costa's book, The other insect societies which includes many ideas for research.

21... Neotropical social mammals require thorough treatment, review, and integration into the broader literature on mammals which is dominated by research in the Paleotropics. In South America, see, especially, caviomorph rodents [infraorder, Caviomorpha], uniting all So. American hystricognaths. n.b. all or most of these spp. are small-bodied, & they are related to Old World [hystricognath] social mole rats.

22... General Patterns...Gene Evolution...Convergence...Gene E. Robinson Lab [see Jenny Tung's preliminary, though, cutting-edge, work on mammals @jtung5]:

https://www.pnas.org/content/108/18/7472

23... Temporal division of labor [age (-graded) polyethism: Wilson 1971] is ubiquitous in social insects; how common is it in Mammals & other vertebrates? See [especially, tables]: Jones CB (June, 1996) Temporal division of labor in a primate: age-dependent foraging behavior. Neotropical Primates 4(2): 50-53.

also, Wilson EO (1971) The Insect Societies. Belknap [HUP], Cambridge, MA.

24. The following book by Bernie Crespi discusses correlates of sociality [p 66, pp 73-74]...note, especially, significance of "high value" of limiting resources [abode, mates, food, etc.]...again, shows need to study limiting resource dispersion [distribution & abundance in time & space]...

Crespi BJ, Morris DC, Mound LA (2004) Evolution of ecological and behavioural diversity: Australian Acacia thrips as model organisms. Australian Biological Resources Study, Canberra.

https://www.environment.gov.au/science/abrs/publications/thrips

25... How much of the variation in mammal behavior & social biology is explained by body size?

26. Nursing [mammary glands] predisposes mammal females to caretaking, dependency, subordinate [e.g., "helper"] status, & favoritism of kin &/or other females. But how are these adaptations affected by evolution in suboptimal ["poor"] conditions or conditions of intense competition [for limiting resources], or, say, drought or collapse of prey population?

27. See Part 4 of Eisenberg [1981] for discussion [also, tables] of mammalian behavior, including mating systems & social biology--see, especially, Chapters 31-33.. Eisenberg [1981] classifies mammal "mating systems" into 10 categories, reduced to 3 basic types: polygyny [1 male, >1 females]; polyandry [multiple-male : multiple female], in which females mate with >1 male [not necessarily "promiscuous", i.e., females may demonstrate selectivity or preferences; also, there may be "favoritism" in which an adult female & an adult male are likely to mate exclusively or commonly with each other]; monogamy [uncommon] 

See Eisenberg's outdated but still interesting and classic paper, Eisenberg JF (1966) The social organizations of mammals, Handbuch der Zoologie, Band 8. Lieferung 39: 10(7): 1-92.

28... Feldhamer GA, Drickamer LC, Vessey SH, Merritt JF, Krajewski C (2007) Mammalogy. Johns Hopkins UP, MD: "typical mammalian pattern of preferring unrelated distant kin as mates;" Emlen's "ecological constraints" model + Trivers' reciprocity [+ "pay to stay"?] explain "helping" in mammals?--especially, patterns in social mole rats [do naked mole rats have castes since there is a specialized "disperser form" in this species?]...see Jarman [1974] for classification of mammalian social organization x feeding selectivity: least selective most gregarious, large, polygamous, & sexually dimorphic--Jarmon PJ [1974] The social organization of antelope in relation to their ecology. Behaviour 48: 215-267...need to integrate Jarmon's findings with those of Crook [1964, Behaviour Monograph X] on weaver birds, i.e. relationship between food dispersion [distribution & abundance] and social structure/organization...

29... Ricklefs RE, Miller GL [2000] Ecology, 4th Edition. W.H. Freeman & Co., NY: Part 4, Population Ecology, Section 4.2, The dispersion of individuals reflects habitat heterogeneity and social interactions--"The dispersion of individuals within a population describes their spacing with respect to one another."--clumped [aggregation (maybe poor choice of word)]--clumped [limiting] resources may be most common determinant of these patterns, also, tendency of offspring to remain in natal group --see #13 above; spaced [even spacing= hyperdispersion]; random ["In the absence of social antagonism, which results in a spaced dispersion pattern or mutual attraction, which leads to clumping, individuals may distribute themselves at random" Can use Poisson methods to evaluate dispersion patterns...also, see Index of Dispersion [Clark & Evans, 1954]...also, can evaluate "nearest-neighbor distance"--"interindividual distance" [IID] in primatology literature...again, see Crook, 1964, Behavior Monograph X...

30... When discussing patterns of grouping or "social" organization [in populations], I have the strong impression that Mammalogists tend to attribute the patterns to phylogeny, philopatry [patterns of dispersal x sex], and/or predation...a Crookian [Behavioral Ecology] framework seems not to influenced Mammalogy very much where a "Crookian framework" would entail the mapping of animals in a population on to the dispersion of limiting resources [distribution and abundance of limiting resources in time and space--ceteris paribus & on average relative to differential engergetics x sex--males, at least, adult males, expected to be "time-minimizers," females, at least, adult females, "energy-maximizers"]...

31... The (2007) edited volume on Rodents by Wolff & Sherman [link] should be read in association with John F. Eisenberg's 1981 book on mammalian "radiations" [op. cit.]...Eisenberg provides broad context for many topics [e.g., parental behavior, scent marking, infanticide]...

https://www.amazon.com/s?k=wolff+rodents&i=stripbooks&ref=nb_sb_noss

32... General patterns in Social Mammals [Social Vertebrates? Social Animals?]: EO Wilson [Insect Societies, Belknap (Harvard), 1971] discussed "age polyethism" ["temporal division-of-labor": TDL; "primitive" (totipotent) eusociality] in social insects as a feature of eusociality, particularly, "primitive" eusociality [taxa displaying "totipotency," the capacity to switch from a reproductive to a non-reproductive state & vice versa, as opposed to "advanced" eusociality, taxa characterized by sterile castes]...this article* provides the first empirical evidence of temporal division-of-labor in a mammal [1996], the mantled howler monkey, Alouatta palliata Gray, studied by the present author in Canas, Guanacaste, Costa Rica. Temporal division-of-labor ["age polyethism," "primitive" (totipotent) eusociality] may occur widely among social mammals, social vertebrates, and, possibly, all social animals, where Cooperation and/or Altruism [including, reciprocity] have evolved in group-structured populations...i would speculate that TDL ["age polyethism;" "primitive" (totipotent) eusociality] is more energetically efficient than more opportunistic, and, perhaps, more flexible or plastic, modes of [social] behavioral expression & might be expected to evolve/occur in contexts favoring conservation of energy [e.g., in heterogeneous regimes]...since females are expected to be "energy maximizers" [metabolically, reproductively], TDL may be more likely to be observed in females compared to males ["time-minimizers"]...TDL is expected to be developmentally programmed [within some (statistically normal) species-typical, population-typical, range (x sex)], & conscious & aware processes may not be required for its generation...in ////?, Jones reported age-dependent expressions of conflict-resolution among adult males of the same Alouatta species in the same location & group; these results require intense investigation, lab & field experiments, & modeling, including, for humans...it is important to investigate those conditions under which different energy-conservation strategies evolve x sex...since males are expected to be more robust under energy constraints, it seems likely that thresholds will be identified differentially x sex for the same endogenous and exogenous, including, social, stimuli/factors/conditions.

EO Wilson's 2019 book, Genesis, advances the idea that many [social] Mammals, including, humans [ see**], may be "eusocial." Where "temporal division-of-labor" ["age polyethism"] is demonstrated, taxa can be classified, "primitively eusocial" and/or Totipotent Eusocial [TE] this classification would apply, also, to any other Social Vertebrates or, indeed, to any other Social Animals, where "age polyethism" [TDL; "primitive" eusocial; TE] is identified. If "tradeoffs" [e.g., energetic, reproductive, survival] are most likely to be observed in "poor" conditions [e.g., heterogeneous regimes where "fitness" is compromised; recurrent drought, unpredictable food or water supply], "age polyethism" may evolve to minimize energetic costs in time and space. While females are expected to be most sensitive to energetic effects, males, also, may benefit, under some conditions, from age-dependent responses. Furthermore, there  may be energetic [reproductive, survival] benefits in coordinating many maturational [age-dependent] and developmental [age-dependent] milestones or markers with one another as genetic and physiological energy-savings tactics and strategies.

33... Wolff & Sherman (2007, link) includes some interesting & useful chapters, though, terminology is not standardized [& is often confusing (e.g., "single-breeding," "multiple-breeding"--particularly, as they are discussed in relation to philopatry...see, for example, Chapter 21 by Lacey & Sherman, who needed to make Emlen's work on Ecological Constraints fundamental to their discussion of "philopatry")], and "species" is often employed where "population" is, rather, the correct term. Each chapter in this book has a Summary at the end that can be read before digging into the whole chapter. Some chapters in Sections, "Introduction," "Social Behavior," & "Comparative Sociality" are of particular interest to students of Behavioral Ecology & Social Biology. There are many allusions to the importance of environmental [exogenous] factors, including, dispersion of resources; however, there is no explicit integration of [John Hurrel] Crookian socioecology [Behavior Monograph X] nor is there integration of Emlen's Ecological Constraints model which is fundamental when combined with Crookian socioecology. For context & references (especially, Emlen, Crespi), see blogpost, this blog, of EO Wilson's, Genesis.

Wolff & Sherman [2007], amazon.com:

https://www.amazon.com/Rodent-Societies-Ecological-Evolutionary-Perspective/dp/0226905365/ref=sr_1_1?keywords=jerry+wolff+rodents&qid=1580071530&s=books&sr=1-1

EO Wilson Genesis review [blogpost, this blog]:***

http://vertebratesocialbehavior.blogspot.com/2019/04/review-of-eo-wilsons-new-book-genesis.html

34... Fundamental questions in Behavioral Ecology pertain to Population Structure relative to dispersion [distribution & abundance] of limiting resources in T(ime) & S(pace), also to Population Structure relative to Basic Laws of Ecology--Acquisition, Consumption, Allocation. Ultimately, we should be able to reduce "fundamental questions" to Thermal Biology [all Biology reduces to Heat], & all material phenomena reduceable to Physics----->expressible in mathematical terms.

31. Towards general principles [GUTs] via studies of Biological Assembly...for group-living---->sociality, see literature in Physics on "queuing"...

... reintegratingbiology.org/wp-content/upl

...as "assembly" patterns & rules are investigated and identified, it is important to address the Physics literature on "queuing" [see my 2014 Springer Brief on mammalian social evolution, Chapter 4]...

...as "assembly" patterns & rules are investigated and identified, it is important not to ignore Thermal Biology pertaining to Social Biology...

35... Needs lots of research: Resource Partitioning in Group-living vertebrates--search for patterns search for rules [within & between trophic levels, including, differential focus on "frugivores," "carnivores," "omnivores," etc.]

36. Mammalian Patterns [here, Rodents]: Chapter 3 in #Rodent Societies [Jerry Wolff & Paul Sherman, Eds, U of Chicago Press, 2007] concludes that most rodents are polygynous or promiscuous [the author prefers the latter]...the litany for #Mammals is that most mammals are polygynous...

37... Mammalian Patterns, Ch. 4 on female reproductive strategies in Wolff & Sherman, op. cit. does not identify general patterns but exposes several problems inherent to the literature on mammalian sexual selection in this book & in many other treatments [e.g., Mammal Societies by TCB, op. cit.]...for example: 1...the reason treatments of male reproductive strategies dominate the literature is that females are a LIMITING resource for males; males are not a limiting resource for females [------>selection]; 2...many treatments, such as this chapter, do not integrate optimality language and logic into their analyses; 3...many/most treatments are not derived from Crookian model of Behavioral Ecology/Social Biology [dispersion [distribution & abundance] of limiting resources [food, mates, sleeping sites, etc.] in Time & Space; 4...many treatments do not integrate Hamilton's Rule & logic into their analyses; 5...many treatments, especially, in Primatology/Anthropology, do not consider the various hypotheses advanced in an attempt to explain Multiple-Mating by Females [in many reports, only Hrdy's idea is advanced and/or the hypothesis that females mate multiply in order to diversify the genetic composition of litters]; 6...Trivers' 1972 chapter in Campbell's volume seems not to have been digested in many treatments of female reproductive strategies [e.g., mammal females, after parturition and after some threshold investment in "current" offspring, are understood to begin investment in future offspring (e.g., repair, mate choice, fertilization, gestation, etc.)]; this generalization may need to be and has been modified for older/old females; 7...females are, cet. par., "energy-maximizers"; males, "time-minimizers"...

38... this is a classic chapter by Jerry Wolff on alternative reproductive strategies in non-primate mammals...

https://www.cambridge.org/core/books/alternative-reproductive-tactics/alternative-reproductive-tactics-in-nonprimate-male-mammals/88AB2B7352642314032233C426A4A231

39.... following Chapter 7, by John L. Koprowski, in Wolff & Sherman...: "Conflict, both intersexual and intrasexual, has been remarkably influential in the evolution of mating systems of tree squirrels. Conflict among males appears to have been particularly important in promoting evasive behavior in females, led to reduced copulatory duration, promoted alternative reproductive tactics, and influenced postcopulatory tactics for minimizing multiple paternity. Conflict among the sexes likely acts to diminish reproductive success of any dominant individual male, as females mate with multiple males and often avoid active pursuit males. The reproductive skew among males, however, is substantial, and active pursuit males clearly are most successful. Intersexual conflict appears to increase the number of males that are able to mate due directly to the evasive behavior of females, a behavior that maintains the satellite tactic among males. The benefits to females of manipulating the types of competition remain unclear. Future research must quantify the costs and benefits of male and female tactics under different environmental and social conditions...." [95]

40... Gene E. Robinson and other researchers have pointed out that, in social insects, "coordination and control" is decentralized, while, in [most?] human societies, "coordination and control" is centralized...is C & C in [most?] Mammal societies [i.e., in most group-living Mammals], centralized? ... my initial impression based upon my knowledge of all mammalian Orders is that centralized group structure is not common ... dominance hierarchies, for example, would be characterized as a type of "Interdependence," a necessary precursor to social behavior [Cooperation] ... thus, perhaps, the evolution of centralized group architecture is evolutionarily "derived" ...

41... In Wolff & Sherman [op. cit.], Chapter Eight by Dobson & Oli, [using PCA] body mass & phylogeny explain most of the variation in life-history traits [age at maturity; age at last reproduction; juvenile & adult survival; fecundity]...these traits predict a species' position on the "fast-slow [life-history] continuum...should this dataset, also, be analyzed by body size separately--"small" Mammals vs "large" Mammals [unless i am mistaken, a "small" Mammal is considered one < 100 lbs]...

42... in the final analysis, is the most important reason to study Primates the fact that such a large proportion of species is group-living ["social"]--structured around philopatric females, often kin?

43... In Wolff & Sherman [op. cit.], Chapter 13 by Scott Nunes, "dispersal and philopatry" is discussed: "The dispersal process can be categorized as either natal or post-breeding.... In mammals, natal dispersal is more common than breeding dispersal, occurring in nearly all species. Natal dispersal has a strong sex-bias in mammals, with males typically emigrating in new home areas at higher rates or over greater distances than females." [150] "A variety of hypotheses have [sic] been proposes to explain the prevalence of female philopatry in rodents and other mammals.... The evolution of complex social systems among rodents and mammals in general has been suggested to be predicated upon philopatry and cooperation among kin living near each other [especially, philopatric females, often kin]." [162]

44... though authors may mention environmental or ecological factors, in general, few, if any, of the chapters in Wolff & Sherman integrate a Crookian model into their analyses [dispersion (distribution and abundance) of limiting resources in Time & Space]--but see Section, Comparative Socioecology, Chapters 29-37...these excellent and important chapters address Families, Genera, & Species that could reasonably become model systems for the investigation of general mammalian patterns, Behavioral Ecology, & Social Biology [Rattus & Mus are already model systems in research Biology and Medicine]...taxa covered are: ground squirrels; marmots; semifossorial desert rodents; Rattus & Mus; Capybaras and Maras; Octodontid & Ctenomyid rodents; rock-dwelling rodents; African mole-rats; black-tailed gunnison's & Utah prairie dogs...

See Emlen's "ecological constraints" model:

http://max2.ese.u-psud.fr/epc/conservation/PDFs/HIPE/Emlen1982.pdf

See Greenwood's classic 1980 paper on dispersal in birds & mammals:

https://psycnet.apa.org/record/1981-29692-001

45... Wolff & Sherman Chapter 14: Gene dynamics and social behavior [F. Stephen Dobson] uses "F" statistics [Population Genetics] to investigate population structure, finding that, in many mammals, population structure is a function of dispersion of female kin groups...n.b. "social breeding groups may slow the loss of genetic diversity from populations," a process adding to the list of benefits to group-living and, possibly, sociality [cooperation, altruism]...indeed, cooperation & altruism may evolve to insure or enhance these benefits [but what are the tradeoffs, the costs?]...though Anthropologists generally maintain that human sociality evolves from an ancestral state of monogamy, the evidence from Mammals summarized in this blogpost strongly suggests that the ancestral state is the female group, especially, the female kin group, responding to clumped, limiting resources [in heterogeneous regimes?]--as most treatments by mammalogists hold...polygyny [and/or promiscuity?] appear to be the most common mammalian sociosexual system, &, perhaps, as suggested by many researchers, males, in part, monopolize female groups to defend females & their limiting resources [saving energy for female "energy-maximizers"]...as an aside, what role dies Sexual Selection play in all of this...

46... is eusociality much more common than we generally think? Bernie Crespi, WD Hamilton, Nancy Moran quoted in this NY Times article linked below...note importance of protected, reliable food source[s] and of protective, reliable housing [& protection from predators--see Bernie Crespi article linked below]...how about humans?; i have suggested that humans are "facultatively eusocial" in my brief communication, "Are humans cooperative breeders" in Archives of Sexual Behavior discussed on this blog and linked below...

https://www.nytimes.com/1993/02/16/science/social-castes-found-to-be-not-so-rare-in-nature.html

"Are humans cooperative breeders: a call for research" (2011), CB Jones:

https://link.springer.com/article/10.1007/s10508-011-9741-5?shared-article-renderer

...thre conditions for the evolution of eusociality, Bernie Crespi [Are these general?]:

https://www.semanticscholar.org/paper/Three-conditions-for-the-evolution-of-eusociality%3A-Crespi/feb94b7e861ac0e14b8d575f39e33c0a28338419

47... when we speak of "generality" we are often speaking of Convergence--whatever our level[s] of analysis from gene/allele to whole organism...here is link to a now classic paper from Gene E. Robinson's lab; note generalizeability, convergent evolution, & "toolkit" concept...see Table 3.1 in my 2014 Springer brief--phylogenetic & convergent social features of "prehistoric" mammals...

https://www.pnas.org/content/108/18/7472


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http://vertebratesocialbehavior.blogspot.com/2020/01/age-polyethism-temporal-division-of.html

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https://link.springer.com/article/10.1007/s10508-011-9741-5?shared-article-renderer

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http://vertebratesocialbehavior.blogspot.com/2019/04/review-of-eo-wilsons-new-book-genesis.html




Wednesday, April 11, 2018

General Principles of Social Ethology (Clara B. Jones, 2013)


General Principles of Socio-sexual Ethology and Organization: A Likely or Unlikely Prospect?

Clara B. Jones (2013)

Introduction
Among terrestrial animals, including humans, socio-sexual ethology and organization (SSEO) has the potential to evolve wherever limiting resources are clumped in time and space. The existence of general, synthetic principles or laws of SSEO, however, remains an unresolved and controversial topic. On the one hand, some researchers are actively engaged in theoretical and empirical programs to detect, describe, analyze, and model patterns among the diverse forms of SSEO within and between taxa (e.g., Emlen & Oring 1977; Bradbury & Vehrencamp 1977; Helms Cahan et al. 2002; Bell & Robinson 2011; Fischman et al. 2011). Other investigators have been cautious in their assessments of attempts advancing unifying properties of SSEO, and some authors have suggested that general principles of SSEO are unlikely to be formulated or that synthetic models are likely to be limited to closely related and convergent taxa (e.g., Crespi 2007; Crespi 1994, 1996, 2005, 2009; Crespi & Choe 1997; Taborsky 2009). Classical ethology has historically emphasized species-typical, discrete (ritualized) signals and displays (“fixed-action-patterns”) responsive to predictable environmental (sign) stimuli (e.g., Tinbergen 1952; Eibl-Eibesfeldt 2007) rather than graded, variable motor patterns favored in heterogeneous regimes (e.g., Jones 2005; Jones & Agoramoorthy 2003). Behavioral and ontogenetic plasticity entailing the study of polymorphisms (genotypically-induced and/or regulated alternative responses) and polyphenisms (environmentally switched alternatives), however, has gained central ground in ethology (the biology of behavior) as a result of renewed interest in the ways that behavioral responses, modified by environmental stimuli, can induce genetic and phenotypic variability (e.g., West-Eberhard 1979, 2003, 2005; Jones, 2005, 2008a; Pigliucci & Muller 2009).
Highlighting SSEO, the present paper assesses ongoing programs actively engaged in a search for general patterns and principles, in particular, unifying models of the diversity of SSEO within and between taxa across space and time. Another objective of the current treatment is to evaluate some researchers’ claims that a few predictive parameters underlie ethological patterns and processes. After arguing for the utility of an integrated search for and formalization of general principles of SSEO, this paper addresses the controversial and unresolved issues surrounding what data, methodological tools, and research designs are required in order to provide robust data for analyses and tests of hypotheses. An important component of this project will be to determine whether the required data and techniques are currently available to investigators. Helms Cahan et al. (2002) suggest that a sufficient database exists to comprehensively search for general ethological principles using character traits. Notwithstanding these authors’ optimism, no consensus regarding terminology, questions, and other requirements has been reached among ethologists studying social biology. This article concludes by considering limitations of current treatments, outstanding questions, and future prospects and directions. In this essay, no attempt is made to review all mainstream efforts to characterize and formalize patterns of SSEO, quantitatively/mathematically or empirically. Instead, I highlight programs of research appearing to me to be clear representatives of different strategies currently employed to discover patterns across and to express synthetic statements about the variability of SSEO within and across species, from supra-solitary (e.g., Emmons, 2000), to cooperative breeders (Emlen 1991), to quasi- or primitively-eusocial (e.g., Jones 2011; Jones 1996; McComb et al. 2011); to eusocial (e.g., Wilson 1971; Jarvis 1978).

General agreement among ethologists about patterning of population structure relative to environment
Ethologists generally agree about overall associations between environmental features and population structure. Vertebrate adaptations have been driven by environmental stochasticity, in particular, variability in food dispersion and quality (Emlen & Oring 1977; Eisenberg 1981; Jones 1980, 1997, 2005, 2009). In brief, first principles of ecology indicate that the size and composition of groups change in response to temporal environmental heterogeneity (e.g., climate) with subsequent consequences for the survival and fecundity of organisms (Pulliam & Caraco 1984; Jones 1997; Wang et al., 2006). Population abundance and structure (e.g., Wilson 1975; Pulliam & Caraco 1984; Wong 2011) through time is an attribute of resource predictability (e.g., Emlen & Oring 1977; Bradbury & Vehrencamp 1977). High resource predictability and high resource quality, relatively homogeneous spatial dispersion of resources combined with resource tracking by the animal population are expected to favor resource defense (e.g., contest competition or territoriality) by individuals or small groups, ceteris paribus. However, low resource predictability and large distance or high variation in distance between resource patches may make resources indefensible (not monopolizeable), yielding large average group size (Schoener 1971; Emlen & Oring 1977; Pulliam & Caraco 1984). Since temporal unpredictability of resources may be positively correlated with spatial uncertainty (“patchiness”), foraging in groups may reduce average search time per individual group member. Thus, environmental predictability will be inversely correlated with group size (Wittenberger 1980; Pulliam & Caraco 1984), reflecting the “environmental potential” of local regimes.
Population structure or socio-sexual organization has significant consequences for genes and the individuals carrying them (Hewitt & Butlin 1997). Population structure may be evident as subdivision into demographic subunits or groups representing an evolutionary compromise among those parameters yielding optimal inclusive fitness to individuals (Wilson 1975; Wittenberger 1980; Pulliam & Caraco 1984; Dunbar 1996) or, more realistically, “best of a bad job” (e.g., Austad and “bet-hedging” (e.g., Jones 1997) tactics and strategies. As Wilson (1975) pointed out, the frequency distribution of group sizes in a population will be a function of those phenomena leading individuals to join and to leave groups combined with the selection pressures on individual responses to these forces (cum stressors). The parameters determining modal group size in a population, thus, are ultimately expressed as adaptations of individuals to local conditions (Pulliam & Caraco 1984; Wilson 1975; Brown 1975; Wittenberger 1980; Dunbar 1996; also see, West et al. 2002).

Have the fundamental parameters of social evolution been specified?
As noted, the overall schema relating local conditions to population structure is not in particular dispute; however, parameters, traits, mechanisms, functions, and adaptive values associated with the template are controversial, especially, the role of predation in structuring populations (see Wilson 1975; Brown 1975). Most contemporary attempts to define and generate unifying models of social ethology, implicitly or explicitly, follow from Emlen & Oring’s (1977) verbal model based primarily on empirical results from avian and amphibian field studies; notwithstanding this restricted database, the paper implied that its formulations were general ones. Emlen and Oring (1977) advanced a synthetic, organizational framework for the evolution of socio-sexual architecture, proposing three predictive parameters: (1) dispersion of limiting resources, (2) the operational sex ratio (OSR:-----), and (3) synchrony of female reproductive cycles. One or more of these parameters has been empirically evaluated and broadly supported for a wide range of plants and animals (both invertebrates and vertebrates), taxa exhibiting virtually every described socio-sexual system and environmental regime.  The present paper’s treatments refer to theoretical work and animal, including human, studies on the evolution of socio-sexual diversity, the latter emphasis consistent with the essential focus of ethology. 
Important research preceded and, subsequently, expanded Emlen and Oring’s (1977) schema. For example, Hawkins (1966, quoted in West-Eberhard 1980), addressing insect sociality, advanced ideas resonant of the later OSR formulation as did Schoener (1971) with his theoretical treatment of sexual dimorphism in the energetics of foraging. Others, (e.g., West-Eberhard 1979, 2003, 2005; Crespi 1996; Frank 1995, 1998, 2006) have provided seminal perspectives on aspects of evolution related to SSEO. Crook, recognized as the inceptor of ecological ethology, conducted classic studies on weaver birds (Crook 1965) and mammals (Crook et al. 1976), the first systematic attempts to correlate socio-sexual organization and ecological heterogeneity, particularly dispersion of limiting food resources. Altmann (1962) and Bradbury & Vehrencamp (1977) addressed temporal and spatial correlates of SSBE, including the spatiotemporal distribution of females as factors influencing the ability of males to monopolize the opposite sex. Unlike Emlen & Oring (1977), however, neither of these papers overtly identified and organized specific parameters within a synthetic conceptual framework. In 1979, Knowlton presented a theoretical model evaluating the spatial and temporal patterning of reproductive synchrony as influences upon socio-sexual variables, particularly, parenting effort. Her treatment, while focusing on a factor, parenting effort, not advanced as a fundamental predictive parameter by Emlen & Oring (1977), showed, importantly, that reproductive synchrony of the sex with greater parental investment rather than female reproductive synchrony, per se, was a definitive predictive variable, revising a feature of the 1977 verbal model. Questions remaining unresolved subsequent to Knowlton’s (1979) work concern how to evaluate differential degrees of bi-parental investment across taxa, and how to assess the relative significance to SSBO of this component of Emlen & Oring’s (1977) propositions. In 2002, Helms Cahan et al. highlighted three reproductive “trajectories” (dispersal, breeding, and alloparental care) as fundamental parameters for investigations of social evolution. Jones et al. (2008), studying mammals with quantitative models, concluded that group size and group sex ratio would predict variations in socio-sexual organization "wherever males compete directly for females."
The empirical and theoretical treatments so far mentioned in this article, as well as numerous other studies, have evaluated the utility of Emlen & Oring's (1977) verbal model, including certain of its limitations and need for refinement. Clearly, many relevant issues remain to be evaluated such as the condition-dependence, tradeoffs, thresholds, costs and benefits, and differential significance of Emlen & Oring's (1977) three fundamental parameters. As empirical research continues to identify patterns and mechanisms of socio-sexual ethology at all levels of biological organization, it is important to emphasize that, despite widespread support for the robustness of the 1977 formulations, mathematical treatments are required to demonstrate that the proposed parameters provide a firm basis, within and between taxa, for fundamental, unifying, predictive principles of variations in SSEO in nature.

Devising research programs to identify principles of socio-sexual evolution within and between taxa
In 1964, Hamilton advanced a general theoretical formulation ("Hamilton's Rule) of social behavior, termed "kin selection" or inclusive-fitness maximizing, that is widely, though not unanimously, accepted to be a general model of inter-individual interactions (see, especially, West et al. 2002). Trivers’ work (e.g., 1971, 1972, 1974; Burt & Trivers 2006) has, also, generated synthetic models of several topics, in particular, parental manipulation, sex-ratio selection, and genetic conflict. Rice’s (e.g., 2000; Holland & Rice 1999) treatments of sexual conflict have provided unifying schemas for co-evolution between the sexes over evolutionary scales. All of these research programs have proven to be rich sources of new hypotheses and investigations, including theoretical and empirical work. The contributions of these and other authors (e.g., Hrdy 1974; Vehrencamp 1983), while synthetic statements, address particular mechanisms of inter-individual interactions rather than parameters hypothesized to predict variations in SSEO over time and space. The fundamental assumption underlying these research programs is that, ceteris paribus, organisms have "solved" similar environmental problems in similar ways (Weinreich et al. 2006), supporting the idea that social taxa have converged on “a similar suite of traits” comprising a “genetic toolkit” (Fischman et al. 2011; Toth et al. 2007; Nygaard et al. 2011).
Although mature theoretical formulations and the new cohort of analytical tools were not available to early ethologists, researchers such as Weiss (1941a, b), Morris (1956), and Ewer (1960) emphasized the importance of understanding mechanisms underlying and regulating action and motor patterns. Contemporary investigations of SSEO utilize sets of data based on environmental, phenotypic, and/or genotypic features. In the simplest case (e.g., Helms Cahan et al. 2002), selected phenotypic character characters (e.g., extracted from ethograms), comparing these within and between taxa (e.g., insects, amphibians, birds, mammals), first qualitatively by “eye-balling” and, subsequently, by methods of correlated trait analysis (see Garamszegi & Møller 2011). These methods have the potential to reveal similar and different patterns of phenotypic characters and to permit inferences about origins and evolutionary “trajectories” of social traits. Correlated trait analyses, thus, do not provide information about causes of patterns detected or their underlying mechanisms. The primary utility of these procedures is the relatively straightforward manner in which preliminary speculations about alternative predictive parameters might be evaluated (see Helms Cahan et al. 2002, Table 1); however, I am not aware of any theoretical or empirical tests of the 2002 schema.
Multi-level studies such as those by Jetz & Rubenstein (2011) achieve a higher level of data integration by mapping variations in environmental or ecological variables (climate stochasticity) to variations in socio-sexual architectures (cooperatively breeding birds), analyzing these results with multi-factorial techniques. Jetz & Rubenstein (2011), for example, were able to determine that climate was more significant than phylogeny as a predictor of worldwide distribution patterns for cooperative-breeding birds. An advantage of this method is its inclusion of a variable (climate) exogenous to phenotypes and potentially significant as a selective force. This approach, like that of Helms Cahan et al. (2002), permits within and between taxa comparative analyses, and it is my understanding that Rubenstein, and colleagues are in the process of incorporating data for cooperative-breeding mammals into their program. A limitation of the work by Jetz & Rubenstein (2011) is that, though environmental heterogeneity is widely understood to be an important factor in the evolution of sociality, local (e.g., resource dispersion) rather than global (e.g., climate) features of the environment are expected to differentiate among SSEO (e.g., Wilson 1975; Brown 1975; Emlen & Oring 1977; Jones l997; West et al. 2002; Jones & Agoramoorthy 2003). “Mapping” spatial distributions of environmental, socio-sexual and/or other features (e.g., genomic characters) is amenable to multi-level geospatial modeling (http://web.cs.dal.ca/~sbrooks/; http://www.proteus.co.nz), and individual-based models (e.g., Thibert-Plante & Hendry 2011) should, also, be helpful utilities for quantitative treatments of some synthetic databases developed to explore the evolution of SSEO. The previously discussed research programs address phenotype or environment--phenotype levels of organization with verbal and correlation analyses. Integrated and complete formulations of SSEO, however, require knowledge of gene/genome---phenotype---environment--- effects.
Studying social insects, Robinson and members of his laboratory (e.g., Whitlock et al. 2003; Whitlock et al. 2006; Toth et al. 2007; Fischman et al. 2011) analyzed molecular pathways of primitively social and eusocial taxa in order to dissect social evolution. This precise though tedious approach requires significant genomic resources, including knowledge of the effects of genes on phenotypes. These investigators’ genomic methods permit within- and between-taxa comparisons; however, knowledge of gene function(s) at the species level is limited for social insects (Fischman et al. 2011) and other groups. Although microarray (gene ontology) analyses do not permit tests of causation, they yield cladograms (Fischman et al. 2011) amenable to quantitative modeling. In addition, knowledge of gene function(s), in particular, the effects of molecular changes, provides information about alternative molecular routes associated with SSEO, permitting inferences about differential evolutionary pathways and constraints, including ecological ones (Fischman et al. 2011), and the latter variable may be the parameter of greatest importance included in the insightful treatment by Emlen (---; Emlen & Oring 1977). Whitfield et al. (2006) and Fischman et al. (2011) provide further discussion of the problems encountered with these techniques, including the contingent nature of inferences about specifics of gene action (e.g., epistasis, pleiotropy) and comparative supra-genomic analyses. The issues discussed in these papers should apply, as well, to other synthetic initiatives addressing the analysis of character traits from the genome level.

Discussion and Conclusions
The more general a model (the more phenomena encompassed), the less realistic it will be. The most parsimonious and comprehensive models of SSEO advanced to date express social traits as functions of organisms’ energetic properties. This approach has a long history, initiated in Oster & Wilson’s (1978, cited in West-Eberhard 1980) “ergonomics” concept whereby group efficiency or output is measured in terms of optimal allocation of energy for survival and reproduction (see, also, Wilson 1971, 1975). Although models of reproductive skew (e.g., Veherencamp 1983) have not been explicitly stated as energetic models, original definitions of differential skew within groups characterized the concept as relative monopolization by one or more group members of total reproductive output of a group (a reproductive unit). Following the perspective of ergonomics, reproductive skew might be formulated as differential energy-investment by group members in (direct) reproductive effort. As a potential synthetic model, reproductive skew is controversial, having received intense scrutiny (e.g., Reeve 200????) since its initial proposal; nonetheless, theoretical and empirical evaluations of the concept’s utility are ongoing (e.g., Hager & Jones 2009).
A recent paper reported that, for social insects, division of labor scales with group size (Holbrook et al. 2011) and, one would add, group density (a measure that should correlate highly with variations in interaction rates). This quantitative treatment is important but highly reductionistic in scope, and many vertebrate researchers are likely to be skeptical that variations in SSEO can be expressed so minimally. Importantly, the new findings are consistent with Emlen & Oring’s (1977) parameterization of ecological factors since these variables determine in large part a local landscape’s potential for sociality via differential dispersion in time and space of limiting resources, measures reflecting relative environmental stochasticity. The findings of Holbrook et al. (2011) are also supported by Wong’s (2011) study showing that group size (and, group density) significantly influences individual survival and reproductive success, leading to differential “decisions” by individuals in response to social, inter-individual stress (c.f. social competition and social selection: Crook 1970, 1977; West-Eberhard 1979; Frank 2006). These developments reinforce the idea that more than one synthetic model of SSEO will be advanced, depending, among other factors, on the nature of phenomena (e.g., energy, phenotypic character states) and level(s) of organization addressed. At least one caveat indicates that the construction of highly reductionistic models may be more complex than it appears on surface based on the work of Hamilton et al. (2011) who found that rules for allocation of energy are effectively equivalent across all mammalian species. This report suggests, then, that principles of scaling may differ for different classes of animals (as a function of body size?).
Notwithstanding the need for further investigation, the SSEO literature provides numerous indicators that energetic factors, in particular, energy savings, are of general import for the evolution of SSEO (e.g., Shoener 1971; Jarvis 1978; Jerison 1983; Lovegrove & Wissel 1988; Heinze & Keller 2000; Jones & Agoramoorthy 2003; Russell et al. 2003; Jones 2005, 2009; Whitfield et al. 2006; Toth et al. 2007; also see Vehrencamp 1983). Following these treatments, it, additionally, seems likely that information about social genetic/genomic pathways sensitive to energy-maximization/optimization and/or energy savings can be expressed synthetically (e.g., Schoener, 1971; Fischman et al. 2011). Other research programs may explore the utility of expressing variations in SSEO as functions of body size (e.g.; Wong 2011) and one or more additional factors (e.g., ecological constraints, life history schedules, phenotypic plasticity).


Data relevant to genomic treatments are in the very early stage of collection for vertebrates, increasing vertebrate ethologists’ reliance upon less ambitious approaches for detection of variations and patterns of SSEO. It seems likely that attempts to express social evolution as general principles will yield more than one model depending upon the level(s) of organization addressed and emphasized by different researchers. Conceivably, different synthetic formulations will be derived for energetic, molecular, genetic, epigenetic, developmental, physiological, and/or phenotypic variables; though, one might speculate that, as Emlen & Oring’s (1977) formulation advances, some ecological measure, in their view, resource dispersion, must be integrated into any predictive schema. It also seems reasonable to conclude that the three parameters suggested by Emlen & Oring (1977) to have general predictive power, may not be the only combination of variables with utility for synthetic expression even though their importance has been ubiquitously demonstrated by empirical research. For example, Frank’s (1998) theoretical work on social evolution led him to highlight three “measures of value”: reproductive value, coefficients of relatedness, and marginal value (and, generation time?). These or other combinations of variables may provide robust models of variations in SSEO across space, perhaps reflecting the complex, multi-determinate nature of sociality or the ability of different metrics to represent assays of fundamental parameters. Finally, the emphasis….throughout this essay on the dependence of variations in SSEO upon variations in ecological, genetic, and/or other limiting factors discounts claims that traits characteristic of SSEO are species-typical (e.g., Hrdy 2009; see Jones 2011), as documented in the technical literature since Crook’s (1965; Crook et al. 1976) fundamental and pathbreaking work.----

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