Mating systems Animal sexual behaviour

1 mating systems

1.1 monogamy
1.2 polygyny
1.3 polyandry
1.4 polygynandry
1.5 polygamy

mating systems

in sociobiology , behavioural ecology, term mating system used describe ways in animal societies structured in relation sexual behaviour. mating system specifies males mate females, , under circumstances. there 4 basic systems:

monogamy

monogamy occurs when 1 male mates 1 female exclusively. monogamous mating system 1 in individuals form long-lasting pairs , cooperate in raising offspring. these pairs may last lifetime, such in pigeons, or may change 1 mating season another, such in emperor penguins. in contrast tournament species, these pair-bonding species have lower levels of male aggression, competition , little sexual dimorphism. zoologists , biologists have evidence monogamous pairs of animals not sexually exclusive. many animals form pairs mate , raise offspring regularly engage in sexual activities extra-pair partners. includes previous examples, such swans. sometimes, these extra-pair sexual activities lead offspring. genetic tests show of offspring raised monogamous pair come female mating extra-pair male partner. these discoveries have led biologists adopt new ways of talking monogamy; according ulrich reichard (2003):

social monogamy refers male , female s social living arrangement (e.g., shared use of territory, behaviour indicative of social pair, and/or proximity between male , female) without inferring sexual interactions or reproductive patterns. in humans, social monogamy takes form of monogamous marriage. sexual monogamy defined exclusive sexual relationship between female , male based on observations of sexual interactions. finally, term genetic monogamy used when dna analyses can confirm female-male pair reproduce exclusively each other. combination of terms indicates examples levels of relationships coincide, e.g., sociosexual , sociogenetic monogamy describe corresponding social , sexual, , social , genetic monogamous relationships, respectively.

whatever makes pair of animals socially monogamous not make them sexually or genetically monogamous. social monogamy, sexual monogamy, , genetic monogamy can occur in different combinations.

social monogamy relatively rare in animal kingdom. actual incidence of social monogamy varies across different branches of evolutionary tree. on 90% of avian species socially monogamous. stands in contrast mammals. 3% of mammalian species socially monogamous, although 15% of primate species are. social monogamy has been observed in reptiles, fish, , insects.

sexual monogamy rare among animals. many socially monogamous species engage in extra-pair copulations, making them sexually non-monogamous. example, while on 90% of birds socially monogamous, on average, 30% or more of baby birds in nest [are] sired other resident male. patricia adair gowaty has estimated that, out of 180 different species of socially monogamous songbirds, 10% sexually monogamous.

the incidence of genetic monogamy, determined dna fingerprinting, varies across species. few rare species, incidence of genetic monogamy 100%, offspring genetically related socially monogamous pair. genetic monogamy strikingly low in other species. barash , lipton note:

the highest known frequency of extra-pair copulations found among fairy-wrens, lovely tropical creatures technically known malurus splendens , malurus cyaneus. more 65% of fairy-wren chicks fathered males outside supposed breeding group.

such low levels of genetic monogamy have surprised biologists , zoologists, forcing them rethink role of social monogamy in evolution. can no longer assume social monogamy determines how genes distributed in species. lower rates of genetic monogamy among socially monogamous pairs, less of role social monogamy plays in determining how genes distributed among offspring.

polygyny

polygyny occurs when 1 male gets exclusive mating rights multiple females. in species, notably harem-like structures, 1 of few males in group of females mate. technically, polygyny in sociobiology , zoology defined system in male has relationship more 1 female, females predominantly bonded single male. should active male driven out, killed, or otherwise removed group, in number of species new male ensure breeding resources not wasted on male s young. new male may achieve in many different ways, including:

competitive infanticide: in lions, hippopotamuses, , monkeys, new male kill offspring of previous alpha male cause mothers become receptive sexual advances since no longer nursing.
harassment miscarriage: amongst wild horses , baboons, male systematically harass pregnant females until miscarry.
pheromone-based spontaneous abortion
in rodents such mice, new male different scent cause females pregnant spontaneously fail implant fertilised eggs. not require contact; mediated scent alone. known bruce effect.

von haartman described mating behaviour of european pied flycatcher successive polygyny. within system, males leave home territory once primary female lays first egg. males create second territory, presumably in order attract secondary female breed. when succeed @ acquiring second mate, males typically return first female exclusively provide , offspring.

polygynous mating structures estimated occur in 90% of mammal species. polygyny common form of polygamy among vertebrates (including humans, extent), has been studied far more extensively polyandry or polygynandry.

polyandry

the anglerfish haplophryne mollis polyandrous. female trailing atrophied remains of males has encountered.

polyandry occurs when 1 female gets exclusive mating rights multiple males. in species, such redlip blennies, both polygyny , polyandry observed.

the males in deep sea anglerfishes smaller females. when find female bite skin, releasing enzyme digests skin of mouth , body , fusing pair down blood-vessel level. male atrophies, losing first digestive organs, brain, heart, , eyes, ending nothing more pair of gonads, release sperm in response hormones in female s bloodstream indicating egg release. extreme sexual dimorphism ensures that, when female ready spawn, has mate available. single anglerfish female can mate many males in manner.

polygynandry

polygynandry occurs when multiple males mate indiscriminately multiple females. numbers of males , females need not equal, , in vertebrate species studied far, there fewer males. 2 examples of systems in primates promiscuous mating chimpanzees , bonobos. these species live in social groups consisting of several males , several females. each female copulates many males, , vice versa. in bonobos, amount of promiscuity particularly striking because bonobos use sex alleviate social conflict reproduce. mutual promiscuity approach commonly used spawning animals, , perhaps original fish mating system. common examples forage fish, such herrings, form huge mating shoals in shallow water. water becomes milky sperm , bottom draped millions of fertilised eggs.

polygamy

the term polygamy umbrella term used refer non-monogamous matings. such, polygamous relationships can polygynous, polyandrous or polygynandrous. in small number of species, individuals can display either polygamous or monogamous behaviour depending on environmental conditions. example social wasp apoica flavissima. in species, polygyny , polyandry displayed both sexes in population. polygamy in both sexes has been observed in red flour beetle (tribolium castaneum). polygamy seen in many lepidoptera species including mythimna unipuncta (true armyworm moth).

a tournament species 1 in mating tends highly polygamous , involves high levels of male-male aggression , competition. tournament behaviour correlates high levels of sexual dimorphism, examples of species including chimpanzees , baboons. polygamous species present high levels of tournament behaviour, notable exception being bonobos.