Darwin's Natural and Sexual Selection

Parasites and pathogens influence mate choice. Males with better immune systems can show more exaggerated traits, signaling better health. Females benefit by choosing these males, potentially getting healthy offspring.

Features like a male's song that attract mates, but don't directly help in acquiring resources.

A measurement of a male cricket's immune response, from a nylon filament implantation.

The way females choose mates based on certain traits, often linking to better genes or health.

Benefits for offspring from choosing a better mate, even if the mating male isn't directly providing resources

Part of a cricket's courtship song, used as a mate-selection criterion.

The ability of offspring to survive and reproduce successfully.

Traits that require effort or resources to develop and maintain by the individuals expressing the trait.

Different strategies males use to reproduce, often due to varying levels of competitiveness. Some males might be more aggressive, while others rely on sneaky tactics.

The dominant reproductive strategy where males compete for resources and territory to attract females. They're often larger and more attractive.

Less competitive males use alternative strategies to access mates already associated with dominant males. This includes sneakily fertilizing eggs or intercepting females.

A male that hangs around a dominant male, waiting to intercept females attracted to the dominant male's display.

A male that sneaks into a dominant male's territory to fertilize eggs, often without being noticed.

An individual's reproductive strategy based on their physical condition or environment. Individuals may switch tactics if their condition improves.

A stable balance between different reproductive tactics where the fitness of each tactic depends on its frequency in the population. This ensures both tactics have similar success.

The fitness of a reproductive tactic depends on how common it is in the population. Rarer tactics may initially have an advantage.

Female spitting spiders choose mates based on pheromones, which signal male quality. This choice leads to larger, healthier egg sacs and higher hatch rates.

Chemical signals released by animals, often used to communicate with potential mates. In the context of spitting spiders, pheromones indicate the male's genetic quality.

The benefits offspring receive from their parents' good genes, even if the father doesn't provide direct care like resources.

A male's strategy to prevent his mate from mating with other males, increasing his chances of fathering offspring.

Male warblers follow their mates closely during their fertile period to prevent other males from mating with them.

Researchers measured how well male warblers succeed in preventing other males from mating with their partners by observing their proximity and following behavior.

The time when a female is able to become pregnant, an important period for mate guarding.

The male warbler stays close to his mate during her fertile period, moving with her and keeping other males away.

The competition between sperm from different males to fertilize a female's egg.

The process of selecting a mate based on certain desirable traits.

Learning about potential mates by observing their interactions with others.

A mating system where one male and one female form a pair bond for the breeding season.

A mating system where one male mates with multiple females.

A mating system where one female mates with multiple males.

Multiple males and females form social groups, and mating occurs within these groups.

Mating between multiple males and females with no specific social associations.

Describes how individuals pair up based on observation, assuming they mate only with their social partner.

Determined by DNA analysis, revealing the actual reproductive partners.

When individuals in a socially monogamous pair mate with someone outside their pair bond.

Females mate with multiple males to improve offspring fitness by selecting genes with desirable traits.

Females choose extra-pair mates with superior genes, even if their social partner is satisfactory.

Increased genetic diversity in offspring from multiple mates reducing risks of harmful recessive genes.

Offspring resulting from mating between socially paired individuals.

Offspring resulting from mating with a partner outside the social pair bond.

A mating system where dominant males defend valuable resources, like food, to attract and mate with multiple females. This strategy gives dominant males greater reproductive success.

Beetles that feed on dead animals (carrion). They play a vital role in decomposition and nutrient cycling.

Explains why females might choose to mate with a male who already has other mates, if the resources he controls make it a better option than being alone.

The male that wins fights, controls resources, and has the highest reproductive success.

A gathering site where males display to attract mates and compete for dominance.

Explains why low-ranking males might gather near dominant males on leks. It's because dominant males attract more females, giving nearby males some opportunity to mate.

Explains why low-ranking males gather near dominant males on leks. It's because areas with high female activity, near resources, are attractive to both dominant and low-ranking males.

A mating system where males compete for dominance, typically over resources or females, to gain access to mates.