5 - Mating Systems & Parental Care Monogamy - male...

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Monogamy - male & female form pair bond - long (lifetime) or short (breeding season) term - both care for eggs & young - rare except in birds (90% of birds) Polygyny - male mates with several females - simultaneous polygyny or successive polygyny - females provide parental care Polyandry - reverse of polygyny - males provide parental care Promiscuity - both male & female mate several times with multiple partners - no parental or either sex may provide parental care
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Ecological conditions favouring monogamy 1) 2) difficult conditions require presence both parents 3) short breeding season requires rapid pair formation - short breeding season - advantage goes to early breeders eg. seabirds such as kittiwake gull - permanent pair cooperate better - egg laying begins earlier - 'divorces' 3x more common among pairs that were unsuccessful the previous season - strong selection to find efficient partner
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Ecological conditions favouring polygyny 1) heterogeneous environment & scarce resource - males defend territories & resource - great variation in quality of breeding site (Polygyny threshold model) 2) biased operational sex ratio a) all females ready at same time - operational sex ratio = real sex ratio = 1:1 - no time for male to mate with >1 female monogamy eg. toad Bufo bufo - all females lay eggs within 1 week - each male only has time to mate with 1 female b) females become receptive in sequence - males successive polygynous eg. bullfrog Rana catesbeiana - females arrive at pond over several weeks - males mate with all arriving females polygyny
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Polygynous mating systems 1) Resource-based polygyny - males territorial - males with no territory never mate eg. bullf frog - males defend areas in pond - females select high quality territories - male mates with all females that come into his territory - intra - 2) Female-based polygyny - males defend females against other males - common in mammals - no male parental care a) female solitary - males guards females over short time - eg. 60% of all mammals b) females social & form harems - a single male guards large group of females during mating season or permanently
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Harem of female Antarctic fur seals ruled by a large male
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3) Lek - males polygynous - male do not defend resource or females - males congregate on 'display' ground Sage grouse - males congregate in Feb. & Mar. - males defend a small area (a few sq m) - females visit males just to copulate - females only select males in centre of lek - males in periphery never mate - 10% males account for 75% mating - strong inter - sexual selection - males provide nothing for the females - females leave after mating - females have free choice
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Why do males aggregate into leks? a) males aggregate to reduce predation risk
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This note was uploaded on 09/26/2010 for the course ENG ELT1106 taught by Professor Mei during the Spring '07 term at 한동대학교.

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5 - Mating Systems & Parental Care Monogamy - male...

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