Lecture 3-Biotic factors that limit species distribution Flashcards Preview

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What are the different types of dispersals

Diffusion or passive dispersal
Jump or assisted dispersal
Secular dispersal


What is diffusion dispersal?

The gradual dispersal of a population across hospitable terrain over a period of generations.


What is jump dispersal

The dispersal across large distances of often inhospitable terrain by individual organisms. often includes assistance by a dispersal agent.


What is secular dispersal?

The diffusion over evolutionary time, where the species is undergoing evolutionary change during dispersal. ex. different song sparrows along pacific coast of NA


What are barriers to dispersal?

1. Physical barriers (mountains, oceans)
2. behavioral/ecological boundaries (predators, competitors,
3. Physiological barriers (temperature, salinity, climate conditions)


What is colonization?

process of dispersing organisms becoming established in new areas. successful colonization requires that conditions in the new area are suitable for the species.


how do conditions become suitable for colonization?

1. Disturbance events can create suitable niches where they did not exist previously
2. A species fills and unoccupied niche or out competes existing species. (typical with jump dispersal)


What is the tens rule?

1/10 imported species becomes introduced (found in wild). 1/10 of those becomes established (self sustaining pop in the wild) and 1/10 of those becomes invasive or a pest species.
1/1000 imported species become invasive


What is the difference between habitat use and habitat preference?

habitat use is when a species is seen at lest once in association with a habitat feature
habitat preference is when a certain species uses something disproportionately to its availability.


how do patterns of habitat selection evolve?

species tend to use habitat that maximizes fitness for survival and reproduction. offspring will inherit the tendancy to select similar habitat features.


do species occupy all potential spaces?

Not all species occupy all of thier potential range because of competition with other species


What is direct competition interactions?

When one species excludes another from some sights by interfering with their usage


What is exploitation competition?

When two species use the same resources, but do not interact directly. one species outcompetes the other for those resources


What is ideal Free Distribution?

1. Individuals are aware of each site, so they can choose the ideal site.
2.individuals are free to more unhindered among sites because they are competitively equal
3. more individuals in an area, lower quality/smaller portions


What does IFD predict?

That animals will distribute themselves among sites in proportion to the amount of resources in each site.


What is Ideal despotic Distribution?

Individuals are NOT FREE to move among all sites because they are not competitively equal. some are superior and inhibit movements of inferior individuals


What does IDD predict?

That more competitive individuals will dominate less competitive individuals from the best sites.


What is Allelopathy?

When one species produces a toxin or chemical that inhibits the growth of another species. Can also be used in agriculture with smother crops to reduce weed over growth


Does predation limit species distributions

yes, but this occurs mainly at relatively small scales ( on a site-by-site basis)


do disease and parasites limit species distributions?

yes, but this differs from predation and occurs mainly at larger scale.