Sexual Selection Flashcards
What is sexual selection?
a subset of natural selection that affects traits related to mate competition and attractiveness
What are the main processes of sexual selection?
Intrasexual selection: Competition among the same sex for mates.
Intersexual selection: Mate choice based on attractiveness.
What is an example of Intrasexual selection ?
fighting in speckled wood butterflies
Why does sexual selection occur?
It arises from the need for reproductive success through mate acquisition.
What are examples of Intersexual selection?
extravagant ornaments and displays, typically in males/ assessment and discrimination (mate choice), typically in females
What is an example of Intra-combined with intersexual selection?
traits used in both intrasexual (male-male) and intersexual interactions
E.g.)antlers in some species–> signal of power and strength in males and admired by females -If in combat however, the horns would easily break off
What is parental investment?
The investment in gametes and care of offspring that affects reproductive rates.
Give an example of asymmetry of in sexes
Differing interest of males and females. Both want many offspring but go about it in different ways
E.g.) Ostrich–> many eggs in different location or less eggs but more nurtured
What is the potential reproductive rate (PRR)?
The maximum number of offspring an individual can produce based on sex and parental care.
Describe female-only care in parental systems.
Males have a higher PRR, while females invest in offspring care.
Describe male-only care in parental systems
Females have a higher PRR, as males invest in offspring care.
What happens in lifetime monogamy with biparental care?
PRRs of males and females become interdependent, leading to sexual monomorphism.
What is the Bateman Principle?
In species without parental care, male reproductive success increases with the number of mates, while female success levels off.
Why is there a plateau in the Bateman Principle graph?
investment in gametes for females is much more expensive
How do species with parental care differ in PRR?
PRR depends on gamete size and the amount of parental care provided by each sex.
Give an example of a species with reversed parental roles.
Seahorses, where males become pregnant and females compete for mates.
What is a key characteristic of species with male parental care?
Females often exhibit brighter coloration and compete for mates.
What is intrasexual selection?
Competition, often male-male, for access to mates.
What is intersexual selection?
It influences the investment strategies of males and females, affecting their PRRs.
How does parental care affect sexual selection?
It influences the investment strategies of males and females, affecting their PRRs
What is sexual dimorphism?
Differences in size or appearance between males and females of the same species.
How does the presence of parental care influence female mate choice?
Females may become choosier to ensure high-quality offspring.
What is the relationship between gamete size and parental care?
Larger gametes (females) often lead to greater parental investment.
Why might females be choosy in mate selection?
To maximize the quality of their offspring through selective mating.
What is the significance of ornamentation in males?
It often plays a role in attracting females during intersexual selection
What does the term “sexual monomorphism” refer to?
Similarity in appearance between male and female individuals, often due to equal parental investment.
How do male reproductive strategies differ from female strategies?
Males often focus on quantity (number of mates), while females focus on quality (mate selection).
Name a species where males display extravagant traits for mate attraction
Peafowl (peacocks) are known for their elaborate tail feathers.
What role does competition play in intrasexual selection?
It drives the evolution of traits that enhance fighting ability or dominance.
How can parental care influence evolutionary outcomes?
It can shape mating systems and reproductive strategies in a species.
Describe the reproductive strategy of the Dotterel.
Males incubate eggs, while females are often more ornamented and compete for mates.
What is the difference between macrogametes and microgametes?
Macrogametes are larger (females), while microgametes are smaller (males).
How does the concept of PRR apply to humans?
Humans exhibit an intermediate PRR between female-only and biparental care systems
What is the evolutionary significance of mate choice?
It can lead to the development of traits that enhance reproductive success and survival
How do species without parental care demonstrate the Bateman Principle?
Males gain fitness by increasing mate number, while females reach a saturation point.
