1. Polygyny

2. How it’s accomplished Diverse strategies have evolved Factors
Female defense polygyny
Resource defense polygyny
Lek polygyny
Scramble competition polygyny
Factors
Female distribution
Food availability
Territory size

3. Female Defense
Females in groups are easy for a male to dominate and monopolize, relative to many dispersed females
Mammals where females live in groups are always polygynous
Lions
Bighorn sheep
Gorillas
Key element is following females, not nests or territories

4. A female defense strategy

5. Passive female defense

6. Resource defense
Females don’t live together, but visit a resource on a regular basis
Male controls the resource, gets access to many visiting females
Floating vegetation
Rotting bark
Rotting fruit

7. Resource defense
Any safe place to lay eggs is a defensible resource

8. Female Perspective Polygyny threshold model
Resource level at which she has more to gain by mating with a polygynist on a good territory than a monogamous male on a poor territory
Predict: female should have same fitness with either type of male if territory is constant
Test: count fledged hatchlings of a songbird that has males that can attract one or two females per season
Result: 1.3 vs 1.6 fledged young (poly vs mono)
Test 2: manipulate habitat so polygynous male is preferable to monogamous male
Result 2: red winged blackbird females pick the male with the best territory, even if she becomes part of a harem (she has almost 2x better reproductive success)
Males may provide good nesting areas apart from each other in his territory so the second female is unaware that she is second. But note song frequency data—reduced when mated once.

9. Scramble Competition
When females are widely distributed (or resources), male territory defense doesn’t make sense
Searching becomes the primary method
Fireflies
Squirrels
Requires different set of abilities—perceptual, endurance, etc.

10. Hippocampal dependence
Hippocampal dependence? Spatial memory for where male had interacted with soon-to-be fertile females

11. Hippocampus and spatial memory
Polygynous voles have sexually dimorphic hippocampal volume
Reproductively active males outperform females on mazes
Males have larger home ranges than females or immature males
Polygynous males expand their home range during the breeding season

12. Size of home range correlates with spatial ability

13. Lekking species
Males gather in groups to display for females, with each male defending a small area of the lek
Searching vs. lek formation?
Not understood, maybe predator defense?
Hypotheses for congregation in leks
Hotspot: males go to territory where females go
Hotshot: males go where the dominant male goes
Female preference for sites with multiple males

14. Hotshot hypothesis Male decoys attract both male and females
Especially very elaborate, attractive male decoys
Lek sites change over time
Removal of popular male (hotshot) leads to lek dispersal

16. Success at the lek
In some species, 6% of males sire 80% of progeny (bats)
In manakins, one male sired 75% of the progeny, a second 13%, and the rest 12%
Males at the center of the lek enjoy more mating success

17. DQ
Benefits to females of lek mating is choosing mates of high genetic quality. Few males tend to dominate the lek. What are the consequences for genetic variability in lekking species? What does this mean for the first idea, that females go to leks to choose good genes? How can we reconcile these findings?

18. A common draw
These tree frogs both respond to the same cues to come to the pond at night