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Social selection is a term used with varying meanings in
biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary ...
.
Joan Roughgarden Joan Roughgarden (born Jonathan David Roughgarden, 13 March 1946) is an American ecologist and evolutionary biologist. She has engaged in theory and observation of coevolution and competition in '' Anolis'' lizards of the Caribbean, and recruitm ...
proposed a hypothesis called ''social selection'' as an alternative to
sexual selection Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (in ...
. Social selection is argued to be a mode of natural selection based on
reproductive The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are a ...
transactions and a two-tiered approach to
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
and the development of
social behavior Social behavior is behavior among two or more organisms within the same species, and encompasses any behavior in which one member affects the other. This is due to an interaction among those members. Social behavior can be seen as similar to an ...
. Reproductive transactions refer to a situation where one organism offers assistance to another in exchange for access to reproductive opportunity. The two tiers of the theory are behavioral and population genetic. The genetic aspect states that
anisogamy Different forms of anisogamy: A) anisogamy of motile cells, B) egg_cell.html"_;"title="oogamy_(egg_cell">oogamy_(egg_cell_and_sperm_cell),_C)_anisogamy_of_non-motile_cells_(egg_cell_and_spermatia)..html" ;"title="egg_cell_and_sperm_cell.html" ;" ...
arose to maximize contact rate between
gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
s. The behavioral aspect is concerned with cooperative game theory and the formation of social groups to maximize the production of offspring. In her critique against the neo-Darwinian defense of sexual selection, Roughgarden outlines exceptions to many of the assumptions that come with sexual selection. These exceptions include sexually monomorphic species, species which reverse standard
sex roles A gender role, also known as a sex role, is a social role encompassing a range of behaviors and attitudes that are generally considered acceptable, appropriate, or desirable for a person based on that person's sex. Gender roles are usually cente ...
, species with template multiplicity, species with transgender presentation, frequencies of homosexual mating, and the lack of correlation between sexually selected traits and deleterious mutation. An article published by Roughgarden's lab on her ideas received criticism in the journal ''
Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence ...
''. Forty scientists produced ten critical letters. The critics stated that the article was misleading, that it contained misunderstandings and misrepresentations, that sexual selection accounted for all the data presented and subsumed Roughgarden's theoretical analysis, and that sexual selection explained data that her theory could not. Other researchers, such as biologist
Mary Jane West-Eberhard Mary Jane West-Eberhard (born 1941) is an American theoretical biologist noted for arguing that phenotypic and developmental plasticity played a key role in shaping animal evolution and speciation. She is also an entomologist notable for her work ...
and
evolutionary medicine Evolutionary medicine or Darwinian medicine is the application of modern evolutionary theory to understanding health and disease. Modern biomedical research and practice have focused on the molecular and physiological mechanisms underlying he ...
researcher
Randolph M. Nesse Randolph M. Nesse (born 1948) is an American physician, scientist and author who is notable for his role as a founder of the field of evolutionary medicine and evolutionary psychiatry. He is professor of life sciences and ASU Foundation Profess ...
, instead view sexual selection as a subcategory of social selection, with Nesse and anthropologist Christopher Boehm arguing further that
altruism Altruism is the principle and moral practice of concern for the welfare and/or happiness of other human beings or animals, resulting in a quality of life both material and spiritual. It is a traditional virtue in many cultures and a cor ...
in humans held fitness advantages that enabled evolutionarily extraordinary cooperativeness and the human capability of creating
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
, as well as
capital punishment Capital punishment, also known as the death penalty, is the state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that ...
by band societies against bullies,
thieves Theft is the act of taking another person's property or services without that person's permission or consent with the intent to deprive the rightful owner of it. The word ''theft'' is also used as a synonym or informal shorthand term for some ...
, free-riders, and
psychopaths Psychopathy, sometimes considered synonymous with sociopathy, is characterized by persistent antisocial behavior, impaired empathy and remorse, and bold, disinhibited, and egotistical traits. Different conceptions of psychopathy have been ...
.


Genetic principles


Portfolio hypothesis

Short for the ''genetic-portfolio balancing hypothesis,'' this idea, proposed by Roughgarden, is used as an alternative to the Red Queen and Mueller's ratchet hypotheses to explain the existence of sexual reproduction within the framework of social selection. In a population with two species which fit the same
ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for ...
, live in the same local environment, have the same degree of genetic diversity, but have different modes of reproduction, sexual and asexual, the sexual species will eventually dominate the local environment. This is due to asexual populations losing diversity for short-term adaptations to the environment. Roughgarden proposes a population of dandelions which fit the above description. The parental generation of a sexually reproducing species and asexually reproducing species contains equal ratios of the three genotypes (A1A1, A1A2, and A2A2). The F1 generation of the asexual dandelions will contain the same ratio as the P-generation. Conversely, following standard principles of sexual reproduction, the F1 generation will be 25% A1A1, 25% A2A2, and 50% A1A2. With the addition of differential survival related to these genotypes (certain genotypes surviving better in different degrees of sunlight), the asexual population will eventually drift toward one genotype and die off when the environment changes to suit a different genotype. The sexual population in the same situation will remain diverse enough to survive changing environments. From this theory, Roughgarden concludes that the main benefit of sexual reproduction is the maintenance of genetic diversity when compared to similar asexual populations.


The IR model of the development of anisogamy

The IR model for the development of anisogamy is named after its developers Priya Iyer and
Joan Roughgarden Joan Roughgarden (born Jonathan David Roughgarden, 13 March 1946) is an American ecologist and evolutionary biologist. She has engaged in theory and observation of coevolution and competition in '' Anolis'' lizards of the Caribbean, and recruitm ...
. By considering the evolution of anisogamy in hermaphroditic marine invertebrates and bisexual plants, the theory postulates of a gene locus which controls both
sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, ...
and egg size produced by an organism. Anisogamy could evolve in
diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...
hermaphroditic adults as an individual adaptation which increases its own fitness.


Hermaphrodism

Hermaphroditic In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have s ...
animals and
dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproducti ...
plants represent a large portion of sexually reproductive species. Under social selection theory, species where individuals produce two different gametes predate strictly
gonochoristic In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...
and
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is ...
species. Separate sexes can, therefore, be described as derivations of primal hermaphrodites. Males arising in primarily hermaphroditic species gain an advantage in certain environments as fertilizers because they lack the energy cost of producing eggs. The development of monoecious and gonochoristic species represents a transition from broadcast fertilization to localized and internal fertilization. Simultaneous hermaphrodism exists in species with pre-Cambrian roots, and several families of organisms have shifted between hermaprodism and gonochoism over their evolutionary history. There are sequentially hermaphroditic species, such as the
goby Goby is a common name for many species of small to medium sized ray-finned fish, normally with large heads and tapered bodies, which are found in marine, brackish and freshwater environments. Traditionally most of the species called gobies have b ...
, which show bidirectional sex changing. The dwarf males of anglerfish in the family Ceratiidae function as "mobile
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...
" for the females of their species.


Behavioral principles


Reproductive transactions

Animals help another in order to access reproductive opportunities. Any inequality in this opportunity is due to predation or resource availability. Therefore, there is value in boosting the reproductive fitness of an animals parents or siblings, both of which share genetic information. Even without this genetic relationship, reproductive transactions can be valuable. Sexual conflict arises from a failure for pairs to negotiate value of reproductive transactions effectively. Mating can therefore serve purposes beyond reproduction, if the maintenance of social structures does not decrease effective fitness. Homosexual mating behavior is observed in species where this is the case. Several asexual species of whiptail lizards have been observed to engage in mating and pair-bonding despite the lack of gametic fusion.


Social state matrices

Animal behavior can be understood as the intersection of three primary elements: genetic foundations, social systems, and individual reaction. A social state matrix is composed of genetic foundations and social systems to determine behavior arising from the intersection of them. For example, animals have genetics which determine reaction to potential foraging stimuli, but only search for the stimuli at certain times of day due to social systems. Therefore, social systems would be selected for which optimize behaviors such as foraging and mate selection.


Criticism

Presented as an alternative to sexual selection theory, social selection has received criticism as a result. Arguments have been made that Roughgarden anthropomorphizes animal behavior in order to suit her theory. Other critics argue that the holes in sexual selection theory which Roughgarden proposes, such as inconsistencies in male and female relationships and critiques of Bateman's principle, can actually be consolidated within the sexual selection framework. An article published by Roughgarden's lab on these ideas received criticism in the journal ''
Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence ...
''. Forty scientists produced ten critical letters. The critics stated that the article was misleading, that it contained misunderstandings and misrepresentations, that sexual selection accounted for all the data presented and subsumed Roughgarden's theoretical analysis, and that sexual selection explained data that her theory could not. Roughgarden stated she was "not altogether surprised" by the volume of dissent and that her theory was not an extension of sexual selection theory.


Alternate uses of the term

The term "social selection" has been used by other researchers to describe elements of the selection process overlooked by the theory of
sexual selection Sexual selection is a mode of natural selection in which members of one biological sex choose mates of the other sex to mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (in ...
, and to view sexual selection as a subcategory of social selection.
Mary Jane West-Eberhard Mary Jane West-Eberhard (born 1941) is an American theoretical biologist noted for arguing that phenotypic and developmental plasticity played a key role in shaping animal evolution and speciation. She is also an entomologist notable for her work ...
used the term social selection to describe differential success in social competition for resources other than mates, which includes female competition for
territory A territory is an area of land, sea, or space, particularly belonging or connected to a country, person, or animal. In international politics, a territory is usually either the total area from which a state may extract power resources or a ...
and competition for parental attention among offspring. Citing
cross-cultural research ''Cross-Cultural Research'' (formerly ''Behavior Science Research'') is a peer-reviewed academic journal that publishes papers in the field of Social Sciences. The journal's editor is Carol R. Ember (Human Relations Area Files). The journal has b ...
conducted by social psychologist David Buss, psychologist Geoffrey Miller has argued that if humans
prefer In psychology, economics and philosophy, preference is a technical term usually used in relation to choosing between alternatives. For example, someone prefers A over B if they would rather choose A than B. Preferences are central to decision the ...
altruistic mating partners that would select by
mate choice Mate choice is one of the primary mechanisms under which evolution can occur. It is characterized by a "selective response by animals to particular stimuli" which can be observed as behavior.Bateson, Paul Patrick Gordon. "Mate Choice." Mate Choic ...
for
altruism Altruism is the principle and moral practice of concern for the welfare and/or happiness of other human beings or animals, resulting in a quality of life both material and spiritual. It is a traditional virtue in many cultures and a cor ...
directly, while
evolutionary medicine Evolutionary medicine or Darwinian medicine is the application of modern evolutionary theory to understanding health and disease. Modern biomedical research and practice have focused on the molecular and physiological mechanisms underlying he ...
researcher
Randolph M. Nesse Randolph M. Nesse (born 1948) is an American physician, scientist and author who is notable for his role as a founder of the field of evolutionary medicine and evolutionary psychiatry. He is professor of life sciences and ASU Foundation Profess ...
has argued that humans with altruistic tendencies receive fitness advantages because they are preferred as social partners, and this enabled humans as a species of becoming extraordinarily
cooperative A cooperative (also known as co-operative, co-op, or coop) is "an autonomous association of persons united voluntarily to meet their common economic, social and cultural needs and aspirations through a jointly owned and democratically-contro ...
and capable of creating
culture Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
.


References

; Bundled references


Further reading

* * * * * * {{Evolutionary psychology Extended evolutionary synthesis Sexual selection