Module #6: Population Patterns Flashcards

1
Q

Population Genetics

A

A group of interbreeding individuals

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2
Q

Population Ecology

A

A group of individuals of the same species inhabiting the same area

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3
Q

Difficulties in defining populations

A
  1. how do you determine inbreeding?
  2. with the definition of population ecology, there is no boundary given (spatially or otherwise)
  3. how does one define the “same area”, or its size?
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4
Q

Difficulties in defining populations

A
  1. how do you determine inbreeding?
  2. with the definition of population ecology, there is no boundary given (spatially or otherwise)
  3. how does one define the “same area”, or its size?
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5
Q

Exponential Population Growth Rate (Density independent growth) + factors affecting it

A

dN/dt = (b-d)N = rN

Factors affecting growth include stochastic environmental changes and disturbances

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6
Q

Exponential growth, solving for population at time t

A

Nt = N0e^rt

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7
Q

Doubling time

A

The time taken for a population to double its size, approximated by n = 0.7/r

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8
Q

Logistic Growth Rate equation (density dependent processes)

A

Dn/dt = rN(K-N/K)

*the closer N gets to K, the slower the rate of growth
*factors that affect logistic growth rates are parasitism, competition, predation

solving for population at time t, you get:

Nt = (N0K)/(N0+(K-N0)e-rt)

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9
Q

r-strategist species

A

They continually colonize temporary habitats, are opportunistic, have high growth rates, high fecundity, and short generation time, put little effort into raising young, so many will perish.

-Migration is a major component of their population dynamic
-“pioneer species” and poor competitors
-named after the intrinsic growth rate, r, in population growth equations

example: american oyster

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10
Q

K-strategist species

A

They live in stable environments, where the generation time is less than the habitat’s life span. They are often large, long-lived, very competitive, low birth/death rates and invest time and effort into raising young.

-they are likely to degrade habitat and overshoot the carrying capacity

examples: human, elephant

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11
Q

Extinction-and-colonization metapopulations (Levins, 1970)

A

A meta population consists of subpopulations characterized by frequent turnover, all subpopulations are equally susceptible to local extinction, and persistence of a species depends on there being enough subpopulations, unoccupied habitat patches, and dispersal to guarantee an equal rate of recolonization

*similar to IBT, but covers one species only
*patchy habitat may dictate existence as a metapopulation
*example: mountain sheep

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12
Q

Loose metapopulations

A

A set of populations of the same species, rates of mating, competition, and other interactions, are much higher within subpopulations than between them

*subpopulations are loosely linked/loosely interacting

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13
Q

Tight metapopulations

A

A set of conspecific subpopulations living in a mosaic of habitat patches, with a significant exchange of individuals between patches. Lots of interchange between subpops.

*Occurs where the distance b/n habitat patches is shorter than the species is physically capable of traveling, but longer than the distance most individuals travel in their life (can move b/n pops but usually don’t).

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14
Q

Source-sink (mainland island) metapopulations

A

Consists of a mixture of small populations prone to extinction and a large persistent population

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15
Q

Habitat

A

A region/area where a species or population usually lives. Characterized by a specific set of environmental conditions such as light availability, temp, moisture, etc.

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16
Q

Habitat Specialist vs. Generalist

A

Habitat Specialist: has very precise living requirements (ex: gopher tortoise)

Habitat Generalist: able to live in an array of conditions (ex: human)

17
Q

Habitat fragmentation

A

the breaking up of large habitats/areas into smaller parcels (ex: deforestation). Very significant for animals and poses a global environmental issue.

Effects:
-generalist species, invasive species, edge species all rise
-extinctions more common since predation rises and populations fall
-specialist species decline