Evolutionary theory Mate desertion

elaborate nest of penduline tit

in penduline tits (remiz pendulinus), uniparental care dominant, , either sex capable of desertion during egg laying period. typically, females care 50-70% of time, males care 5-20% of time, , both parents desert 30-40% of time, condemning offspring death. in system, males build elaborate nests , desert once these nests have been filled females eggs. result, in response, females have adopted 2 counter-adaptive behaviors function deceive male regarding clutch s progress. females conceal eggs burying them , aggressively attack males approach nest during egg laying period. indeed, studies have shown high correlation between length of time male stays before deserting , number of days female keeps eggs buried. relationship suggests egg burial has evolved adaptive female behavior attempts control information males use decide whether or not should desert.

response desertion

after 1 partner deserts, remaining partner has 3 options. first, may attempt raise young on own. occurs when investment required 1 parent raise current offspring maturity less needed produce new offspring. result, remaining partner forced situation trivers coined “cruel bind.” here, deserter forces partner stay, gaining benefit of deserted parent s continued investment @ cost of additional mating opportunities deserted parent.

second, if cost of raising offspring alone high , cost of remating low, deserted individual may choose desert offspring , attempt breed again. in cases, second deserter may take part in filial cannibalism, reaping lost investment eating own offspring nourishment. example, in scissortail sergeant fish (abudefduf sexfasciatus), male parental care dominant, , males undergo brood cycling in alternate between mating , parental phases. when broods artificially reduced in breeding phase, male scissor-tail sergeants more cannibalise eggs , return mating phase, because reduced broods indicate decreased current reproductive success.

lastly, deserted individual may attempt trick mate helping provide care young, circumventing cruel bind. instance, female cuckolds male, deceiving him raising male s offspring, benefits reducing amount of care must provide , conserving resources future reproduction. in response, evolution of counter-adaptations allow males guard against female deception expected, evolutionarily maladaptive organism invest in unrelated offspring.