Lecture 10: THE EVOLUTION AND ECOLOGY OF SPATIAL DISTRIBUTION

What is natal philopatry?

When offspring remain in their birth area and share their parents' territory throughout life.

What are three costs of natal philopatry?

Increased resource competition, inbreeding, and reproductive suppression by adult breeders.

How does inbreeding reduce fitness?

It increases the expression of recessive alleles, which can lower offspring fitness.

What is reproductive suppression?

Adult breeders preventing younger individuals of the same species from reproducing via chemical or behavioral methods.

What are some benefits of natal philopatry?

Remaining in a familiar, suitable environment and having an advantage finding resources and avoiding predators.

What is natal dispersal?

The movement of an animal away from its birth area to establish elsewhere.

What are some benefits of natal dispersal?

Reduced competition with relatives, decreased inbreeding, and reduced reproductive suppression.

What are the costs of natal dispersal?

Increased predation risk and energy required for travel, plus entering less suitable habitat.

What determines whether an animal can disperse?

Sufficient size and strength to leave its natal location successfully.

What is sex-biased natal dispersal?

When one sex is more likely than the other to disperse from its natal area.

What four factors influence sex-biased natal dispersal?

Inbreeding avoidance, local resource competition, local mate competition, and kin cooperation.

How does sex-biased dispersal balance inbreeding and philopatry benefits?

One sex disperses to prevent inbreeding, while the other remains in a familiar habitat.

How does territory acquisition and defense influence which sex disperses?

The sex establishing and defending territories stays because spatial familiarity provides a competitive advantage.

How does mate-defense polygyny influence mammalian dispersal?

Males compete for females, causing young or losing males to disperse to find mates.

How can breeding-site choice influence sex-biased dispersal?

The sex choosing breeding sites first remains, while the other disperses to avoid inbreeding.

What is the local mate competition hypothesis?

Sex differences in mate competition influence which sex is more likely to disperse.

How does kin cooperation influence natal philopatry?

Cooperation makes staying advantageous for the sex that benefits most from family cooperation.

What are the three phases of habitat selection?

Search (looking for habitat), Settlement (establishing territory), and Residency (becoming established).

What resources do animals evaluate when selecting a habitat?

Food, water, nesting sites, and comparison with their natal habitat.

How does the presence of conspecifics affect habitat selection?

Conspecifics signal resource availability, but high density increases intraspecific competition.

What is public information in habitat selection?

Information obtained by observing the characteristics or reproductive success of other individuals.

How can other species affect habitat selection?

They can create interspecific competition or provide mutual benefits like predator detection.

What is the comparison tactic of habitat searching?

Visiting several habitats, revisiting promising ones, and selecting the highest quality area.

What is the sequential search tactic?

Evaluating one habitat, accepting or rejecting it, and moving forward without revisiting past sites.

What is Natal Habitat Preference Induction (NHPI)?

The influence of early experience in the natal habitat on subsequent habitat selection.

What are three benefits of Natal Habitat Preference Induction?

Shortened search time, easier identification of suitable resources, and improved phenotypic fitness.

What is migration?

Relatively long-distance, seasonal movement triggered by climate, food, season, or mating.

What qualifies animal movement as true migration?

It occurs annually or seasonally, or involves a major lifelong habitat shift.

What is two-way migration?

Migration where an animal departs from an area and later returns.

What is one-way migration?

Migration where an animal leaves its original range for a new location and never returns.

What is obligate migration?

Migration that individuals of a species are required to undertake.

What is facultative migration?

Migration that individuals can choose whether or not to undertake based on conditions.

What is the difference between complete and partial migration?

Complete migration involves all individuals; partial migration involves only a subset of the population.

What is differential migration?

A type of partial migration based on distinct demographic characteristics such as age or sex.

What is multigenerational migration?

Migration completed over multiple successive generations rather than a single individual's life.

What are daily migrations?

Regular movements performed by animals within a single 24-hour cycle.

What are irruptions?

Irregular, non-cyclical animal movements caused by pressures like famine, overpopulation, or disasters.

What are four costs of migration?

High energy expenditure, increased predation risk, adverse weather vulnerability, and difficult terrain obstacles.

How do predators take advantage of migrating animals?

They wait along migration bottlenecks or follow herds to target weak individuals.

How can weather threaten migrating animals?

Sudden, unexpected extreme weather events can cause mass mortality among migrants.

How do terrain and human structures threaten migrants?

Crossing oceans/deserts hazards migrants, while dams, wind turbines, and lights cause lethal collisions/disorientation.

How does migration benefit food availability?

It allows animals to move from seasonally scarce regions to areas rich in food.

How can migration benefit resource recovery?

Leaving depleted areas allows local vegetation and resources time to regenerate before animals return.

How can migration improve reproductive success?

It grants access to safer breeding environments with optimal shelter, climate, and food.

How can migration reduce predation and interspecific competition?

It leaves non-following predators behind and relocates populations to less crowded, specialized niches.