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Avian Mating Systems Table 13-1 Monogamy 90% Polygamy Polygyny 2% Resource defense Female defense Male-dominance Polyandry 1% Polygynandry 1% Promiscuity 6%. Behavioral Monogamy - most prevalent. What leads to different strategies? Why Monogamy?.
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Avian Mating Systems Table 13-1 Monogamy 90% Polygamy Polygyny 2% Resource defense Female defense Male-dominance Polyandry 1% Polygynandry 1% Promiscuity 6%
What leads to different strategies? Why Monogamy?
But extra pair copulations common in many behavioral monogamous birds EPC’s vs EPF’s Why? Direct Genetic
Polygyny –Resource –defense - Redwinged blackbirds Inter vs. intra sexual selection Nice territory! Look at those epaulets! Orians’ Polygyny Threshold Model
Polygyny – • Female defense (Harem) – Grackles • Wild Turkeys – winter flock • sibling males and • harems of 4 -7 females
Polygyny – Male hierarchy “lekking” Open area grouse - Sage grouse, prairie chickens , manakins
Polyandry Sequential – phalaropes Simultaneous – spotted sandpiper and jacanas
Promiscuity Forest grouse are solitary Ruffed Grouse, Blue grouse Hummingbirds
The Ruff and multiple mating male strategies Territorial Homozygous recessive Territorial Shorter-lived 89% of copulations if with a sattellite Satellite: Heterozygous Non territorial Longer lived 11% copulations
What leads to different strategies? Polygyny / Promiscuity and lekking? OSR Hot spots Hot shots Female preference Polyandry? OSR Clutch Size Limitations?
Increasing variance in reproductive success leads to increased sexual selection Promiscuity > Polygyny = Polyandry (reversed SD) > Monogamy 100 % of males contributing genes 0 Species
Convergence (sort of) in African widowbirds Shabby epaulets! Run-away selection – Based on female preference linked to male trait What a tail!!
Sexual selection can lead to ever more elaborate displays in plumage Hummingbirds Neotropical and Nearctic
In some cases, both sexes display ornament, though males’ may be larger Black-billed Magpie Scissor-tailed Flycatcher