Sexual Selection Flashcards
The number of offspring “left behind” is not the only important factor in reproductive success. What is the other? What is it dependent on?
Quality (heath, reproductive potential, etc.).
Dependent on “quality” of parents.
What become crucial factors in the reproductive success of an individual?
Mate choice, competition for mates.
Define intra-sexual and inter-sexual competition.
Intra-sexual: males or females competing with each other.
Inter-sexual: males or females choosing their mates.
Mate choice in inter-sexual competition often involves what two things?
Courtship and courtship rituals between sexes.
Advertisement by males and choice by females.
The original view of sexuality was posited by which two people? What did it entail with males and females?
Darwin, Trivers.
Males: competition for access to resources, including females.
Female: selection for choice.
What are three reasons for choosy females in mammals?
Limited number of ova.
Child bearing is costly.
Lactation is costly.
What is the prediction and consequence of the original view of sexual selection?
Prediction: ovulating females are limited resources for males.
Consequence: reproductive mistakes are much more costly to females.
Regarding intra-sexual selection, competition before mating involves which two groups? Provide an example.
Cervidae, bovidae.
E.g., male bucks obtain feeding areas prior to mating by fighting with each other.
Regarding intra-sexual selection, provide two examples of competition after mating. What happened in both?
Pride take-over by strange male lions and infanticide.
Bruce effect in mice (pheromonal abortion of female mice by arrival of strange males).
Receptivity of females and mating immediately follows.
Male-male (intramale) competition is common in _____ species.
Polygynous.
List three means of male-male competition.
Aggression (fights, ritualized aggression).
Sperm competition.
Kleptogamy: surreptitious mating: cuckoldry, sneak-mating.
In males, competition for access to resources may explain what?
Slower maturity in some species.
Independent of competition, what is the relationship between males-males, females-females, males-females?
Males evaluate/assess each other (competition).
Females evaluate/assess each other (competition).
Males and females evaluate/assess each other (choice).
Many vole species are monogamous. Despite this, what will some females do to be impregnated and why?
Impregnated from neighbouring male, despite selecting one to live with and act as father already.
Father figure has lower androgen levels, therefore better father; mate has higher androgen levels.
Describe the practicality of testosterone when young and when older.
Useful when young, can be detrimental when older (e.g., lower lifespan, susceptible to disease).
What helps a mate determine androgen levels?
Secondary sex characteristics.
What is generally assessed to determine “quality” in a mate?
Immune and endocrine systems.
How does the peacock exemplify the handicap principle? How is it a superhonest characteristic?
Tail so large, can’t evade predators.
Despite large tail, still alive, therefore suggests viability.
Why are reproductive mistakes especially costly for mountain gorillas?
3-6 year birth intervals.
Describe K-selected species versus r-selected species.
K-selected: quality over quantity; “sedentary.” Slower development, long gestation, more parental care.
r-selected: quantity over quality; “opportunistic.” Rapid development, short lifespan, unstable environments.
What is a typical example of a K-selected species and an r-selected species? Do they have high or low amounts of intraspecific competition?
K-selected: African elephant. High competition.
r-selected: most mouse-like rodents. Low competition.
Extensive and prolonged parental care and parental dependency are common to species depending on _____.
Low access food.
_____ have the longest periods of dependency, but they also have flexible behaviour and impressive learning abilities.
Primates.
