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Population and Community Ecology > Dispersal > Flashcards

Flashcards in Dispersal Deck (10):
1

Whats dispersal?

Process by which species enter a local community from the surrounding area

2

What is alpha, beta and gamma diversity?

Alpha (α) diversity: number of species in a local community; avg. # of species in
local communities

Beta (β) diversity: species turnover among local communities (various formulas); effective # of
 distinct units

Gamma (γ) diversity: number of species across a broad region; regional sp. pool

3

Local vs regional species richness?

Greater regional influence
(dispersal)
Greater local influence
(selection,drift)
-Local species richness increases with regional dispersal rate

4

Explain neutral model with dispersal.

-Fixed # of individuals in local communities
-Lottery model with local drift
100 species in regional pool
-Varying dispersal rates (m)
into 4 local communities

5

Island biogeography

Turn over and species richness intersect

6

Whats turn over rate?

-Number of species reaches equilibrium, but species composition is continually turning over
-Equilibrium rate of immigration of extinction

7

Effect of dispersal- island mainland vs far islands

-Islands close to mainland have higher immigration than far islands
-Leads to higher species richness and turnover

8

How do large islands effect extinction?

-Large islands have lower extinction than small islands
-Leads to higher species richness and lower turnover

9

Species-area relationship

-Area effect produces well known relationship between size of an area (A) and the number of species (S) there

10

Rescue effect and target effect

-Rescue effect: closer islands have lower extinction 
(same idea as for metapopulations)

-Target effect: larger islands have higher immigration