Sexual selection in animals Flashcards
What is the paradox of sex?
Who gets most genes into the next generation.
Sexual reproduction?
Each offspring has 50% mother’s genes.
Asexual reproduction?
Each offspring has 100% mother’s genes.
Benefits of asexual reproduction?
No need to find a mate/female, every individual can reproduce.
Why is sexual reproduction less efficient?
Only half individual’s genes are present in each, males don’t produce offspring directly.
Cons of courtship and mating?
Takes time, energy and is dangerous, finding right mate not easy, courtship attracts predators, risk of parasites/ disease and physical injury.
Advantages of sexual reproduction at individual level?
More variation in offspring, sibling competition reduced, better protection to parasites.
Advantages of sexual reproduction at population level?
Muller’s Ratchet, Hill-Robertson effect, sexual species survive longer.
Why consider individual benefits too?
Evolution depends on selection of individuals, first mutant from asexual to sexual had to outcompete, benefits from population wouldn’t spread new allele, not for the good of population.
Why are aphids and water fleas asexual most year and sexual in winter?
Produce eggs over winter so offspring don’t emerge for months, happens before uncertain future environment.
Pros of variable offspring?
Don’t have to worry about uncertain future conditions.
Asexual vs sexual environments?
Stable vs unstable.
Benefits of reduced sibling competition?
Offspring survive in many different habitats, compete less as fewer in any one patch, benefit to individual parent as offspring do better.
How does sexual reproduction protect against parasites?
Helps hosts win evolutionary arms race between hosts and parasites/disease.
Characteristics of evolutionary arms race?
Hosts evolve to repel parasites, parasites evolve to penetrate defences, parasites smaller so breed faster and win race.
Pros of sexual reproduction in arms race?
Variable offspring share fewer parasites with parent, benefit to individual parent, relief from parasites for offspring.
Muller’s Ratchet?
Gradual accumulation of deleterious mutations.
Hill-Robertson effect?
Getting multiple mutations into one individual is easier in sexuals (due to recombination).
Do sexual or asexual species survive longer?
Sexual.
Why do asexual species occur less frequently/ go extinct more often?
Inability to adjust to new habitats.
