10 9 Mating Systems Male Some species the mates access is limited by access to females Social association and the number of sexual partners an individual has per breeding season Female A female s success is limited to by access to resources The males will boost RS by mating with more than 1 female Birds females invest 50 of body weight to make clutch of eggs Female birds can obtain all the sperm she needs to fertilize all her eggs Male bird can fertilize all eggs but females still look for more males Females increase RS by getting male parental care and high quality territory and food Monogamy 1 male and 1 female Male has sole access to 1 female in a breeding season Polygamy males and females Have multiple mates in a breeding season polygny 1 male and 2 or more females 1 male has sole access to several females in one breeding season polyandry 1 female 2 or more males 1 female has sole access to several males in a breeding season Serial monogamy 1 male and 1 female per breeding season next season a different male and Pair Bond 2 individuals male and female that are living a close association with eachother in a breeding season female longer term relationship raising offspring biparental care Stephen Ethlem and Lewis Oring Two Factors that caused evolution of different mating seasons 1 Sexual conflict Male and females have different goals Ideally female would want monogamy but this only happens if there hgih resource levels Female would prefer polyandry if the multiple males can care for her offspring Ideally the male wants polygamy because multiple partners lead to higher fitness RS 2 Ecological factors Resources limited Resource distribution affects cost benefit of various mating system Females need a lot of resources 1 Monogamy Extremely rare in animals mammals including primates Lifetime monogamy is rare Serial monogamy is more common Access animal 37 of all mammal species are monogamous Non existent in large conspicuous diurnal species Why See Easy to cheat Extra pair copulation EPC Classical monogamy common among small diurnal species Example Old field mouse peromuscuc paliometes live in burrows underground Dr David Foltz Evacuated over 500 burrals Tracked mating pair over many years Genetic analysis of all offspring Behavioral studies What did he find 1 Genetic analysis of 90 of offspring in a burral belonged to the adult male in that burrow 2 13 of burrows did not contain 1 male 1 female in it other males or did males die Why would males choose monogamy look at fitness related to male choice for females He did 2 experiments 1 One male exposed to female 1 and female 2 female 1 preferred by male Male 1 X Female 1 Also forced male 1 to make with female 2 Male 1 X Female 1 23 offspring Male 1 X Female 2 18 offspring Fitness associated with mate choice Follow up experiments Male 2 mated with the same female 1 Male 2 X Female 1 19 offspring Male 2 X Female 2 18 offspring Basically the same thing Depends on some hidden choice preference effects number of offspring Cost benefit of monogamy for males Cost HUGE House wrems birds 1 male X 2 females 9 offspring 1 male X 1 female 6 offspring Benefit California Mouse Fathers participate in parental care Pups born in coldest months and cannot maintain own body temperature for the first 2 weeks of life Requires both parents in burrow for heat huddling Lab Experiment Cold temp 2 groups 1 gave food all offspring survived 2 Male leaves nest to get food Had to run on a wheel to get food decrease offspring survival If male leaves offspring dies so male has to stay in order to increase RS 2500 species parental care not important for driving monogamy Distribution of females example Clown shrimp Friends widely scattered Reception every 3 weeks the male waits because he may not find another female this is an example of mate guarding Dik Diks antelopes Monogamous for years Male provides no parental care No protection against predators Too much territory for 1 male to guard more than 1 female Female Dik Dik Estrous in heat when they pee when they re in heat their pee has a different smell so male tries to stop that smell from being exposed to other males so he kicks dirt over pee and defecates on it Female enforced monogamy Burying beetle Male polygamous Male and female find carcass Female lays eggs on carcass when eggs hatch they feed on the carcass so very little parental care Carcass can feed more than 1 female s worth of eggs Male good size carcass can fit more eggs Climbs up onto mound and release pheromones which attract another female The first female knocks down the male and doesn t allow male to get up high and release pheromones tethered the female so she couldn t knock does male male released more pheromones Lab Monogamy is rare Drives scarce resources wiudely spread females parental care male wants to ensure all the offspring are his Male costs are huge decrease reproductive success Females benefits are huge increase reproductive success Polygyny 1 male several females Extreme and intense competition to mate with as many females as possible Few males will have extraordinary fitness and increase reproductive success Under what conditions would you find polygyny Directly defended females Indirectly defending resources a Female defense polygyny australian wasp males always hatch earlier in the season than females male flies around looking for female eggs brood eggs male guards the female eggs and wait till they hatch when females hatch they are ready to mate all of his offspring in all these females Female defense polygyny works under certain circumstances females short lived low fecundity ability to reproduce in females mate has more sperm than it takes in 1 female females mate soon after born females are always grouped together brood cell b Resource defense polygyny good resources more females poor resources 1 female c Lek polygyny temporary territory specifically for mating no apparents resources there no food shelter always along a well traveled route that the female takes many specifies travel great distances in their lifetime scarce food resource times at a lek Females choose the male Males gather in lek there are many leks Females walk around Males strut their stuff 10 males in a lek not all will get reproductive success Bearded manakins birds 438 copulations their center male did 75 of all copulation 388 the second male 13 copulation 56 sixth other 2 of copulation 10 Two get 0 Why would a male be in a lek Females are there Because