Sexual Selection Flashcards
This reproductive method typically prevents extensive parental care (fish are an exception)
Spawning
What are the three ways (three answers) for sexual selection to occur?
- Mate choice
- Contests
- Sperm competition
How is runaway sexual selection counteracted?
Stabilizing selection levels it out
What is the primary differentiator for fitness
Female choice
Graph in middle of slide 3
Graph in middle of slide 3
Individuals coming together to reproduce
Copulation
Better guarantee of successful reproduction, promote competition among males for more possible variation, and multiple males can produce more resources for the female
Polyandry
Requires time and energy searching for mates
Copulation
Oldest and largest individual is a male; he maintains a harem of females all of whom he fertilizes
Polygyny (middle of slide 2)
What are the two basic kinds of reproductive modes
Copulation and spawning
What are the costs of more extreme morphologies?
They cost more energy to make and they often create a more obvious sign to predators
Opposite of random mating
Assortative mating
Underlying driving force for sexual selection
Bateman’s principle
Cricket example on top of slide 5
Cricket example of top of slide 5
What requirement of HW does sexual selection violate?
Random mating. Mate preference in sexual selection violates this
Males have elaborate versions of a trait and females have a preference for it. Males having that trait shows they have passed the test of survival
Zahavi’s handicap hypothesis
This requires females to exert choice, males to have extreme morphologies compared to females, and males differing in terms of the expression of the extreme morphology
Zahavi’s handicap hypothesis
END OF SLIDE 1
END OF SLIDE 1
This reproductive method has a high gamete mortality
Spawning
Preference by one sex for certain phenotypes in mates
Intersexual selection
Method of sexual selection involving male-male fights or sexual coercion (use of force or threat)
Contests
Method of sexual selection involving competition within a single female between the sperm of multiple males
Sperm competition
A component of natural selection that explains differences in mating success
Sexual selection
Method of sexual selection involving female or male choice
Mate choice
Preference for similar phenotype (may lead to inbreeding depression which is a drop in fitness)
Positive assortative mating
How do choosiness and elaboration reinforce each other?
Females choose the elaborate traits which correlate with high fitness so the offspring will have higher fitness as well
Selection based on proxies for health and general quality. Individuals choose healthy individuals of high fitness
Mate choice
How can we determine what trait females are selecting for and why?
Plotting the trait with fitness and looking at correlation. Covariance between the trait and relative fitness
Males maximize mating opportunities
Polygyny
What things typically act as cues in female choice?
Features that suggest health and capability of breading, features that emphasize distinction between males and females, and novelties that suggest that males are from another pop
Between members of one sex for access or opportunity. Females picking a male to mate with
Intrasexual selection
What are sneaker males?
Opposite of dominate males. They act like females to get into group and then mate with the females once theyre in
Female reproductive success limited by resources and male reproductive success limited by access to mates
Bateman’s principle
Requires coordination of members of a pop with respect to timing. All organisms of a species need synced up timing
Spawning
Female choosiness and male elaboration form a positive feedback loop. The trait becomes so extreme it lowers the fitness
Runaway sexual selection
Raise your chances by mating more or having more gametes
Indirect male-male competition
Why cant random mating ever occur?
Mate preference exists, geographic barriers exist, and fertilization advantages exist
This reproductive method requires gamete recognition systems that are very elaborate
Spawning
How do offspring that resemble their fathers do with reproductive success and fitness?
They have greater reproductive success and thus higher fitness
Selection arising from differences in mating success
Sexual selection
SLIDE 7 BIRDS EXAMPLE
SLIDE 7 BIRDS EXAMPLE
Oldest and largest individual is a female; multiple (smaller males) compete for access
Polyandry (middle of slide 2)
Why are females often more choosy?
They produce the more expensive gamete and have more post mating responsibility. Female strategy is focused on obtaining the best mate so that her investment in eggs pays the greatest genetic dividend
Preference for different phenotype (may make it hard to maintain species boundaries)
Negative assortative mating
What determines what sex will be more choosy?
Whatever sex is investing more energy will be choosier
Requires individuals recognizing and encountering conspecifics (individuals of some species) of the appropriate sex and a means of transmitting gametes
Copulation
Sub section of natural selection that still has selection at play
Reproductive modes
What requirement of HW does sexual selection less obviously violate and why?
All offspring have an equal chance of survival and reproduction because this is violated by natural selection and sexual selection is a form of natural selection
Shooting out gametes in hopes of zygote formation
Spawning
How is Zahavi’s hypothesis a form of honest advertisement?
Males advertise themselves as high quality by showing they have the extreme morphology and are living
