Sexual Selection and Mating

In most species, males make up half the population yet bear no what

No direct offspring

Males generally don't contribute to what

The survival of offspring

Asexual lineages arise

Spontaneously

Many species can toggle between what

Asexual and sexual modes of reproduction

In asexual organisms, all of what are passed down from the single parent

Alleles

In an ideal situation, what type of sexuality would be at a greater advantage

Asexual females

Sexual displays and rituals can be enormously what

Expensive in terms of energy, time, etc.

Red Queen Hypothesis

Sex and recombination provides the variation that is necessary for evolution and survival

Long term evolutionary arms races are suggested where

In the fossil record

In shorter time scales, evolutionary arms races are easier to what

Easier to find

Asexual strains suffer far more what the sexual strains

Parasitism

Why do many species switch between sexual and asexual reproduction

They use sexual reproduction when change is needed, and asexual reproduction when environment is constant

Sexual selection

Subset of selective pressures with attracting a mating partner

Does every species experience sexual selection

Yes

Darwin viewed sexual selection as ____________ from natural selection

Independent

Females generally are defined by contributing more what to reproduction

Energy, care, etc.

Male fitness depends on what

Finding as many mates as possible

Female fitness depends more upon what

Finding the best possible mate(collecting resources for reproduction)

Two basic mechanisms of sexual selection

Male male competition

Female choice

Male male competition

Males compete for access to females

Female choice

Selection imposed by females when choosing males

monogamous mating system

Males and females pair for the breeding season(for life in some instances)

Polygynous mating system

Males have multiple female partners in a breeding season

Sequential polygyny

Male visits with successive females

polyandrous mating system

Females have multiple mating partners

Resource based mating systems intensify what

Male male competition

In polygynous species, males often do not generally provide what

Any parental care