Lecture 10 Dispersal, metapopulations, and island biogeography

Question 1

are real populations close systems (settings that cannot transfer energy to their surroundings)

Answer 1

no

Question 1

dispersal definiton

Answer 1

individuals moving from one population to another

Question 2

What does Dispersal allow organisms to do? CEI

Answer 2

Colonize new areas

Escape competition

Avoid inbreeding depression (reduced survival and fertility of closely related individuals)

Question 3

what helps taxas disperse

Answer 3

evolving traits that aid in dispersal

Question 4

why is dispersal important? (4) CRIC

Answer 4

for colonization of new habitats

range shifts due to climate change

islands

connecting populations

Question 5

metapopulation

Answer 5

group of spacially separated populations of the same species which interact at some level

Question 6

patch

Answer 6

spatially distinct population

Question 7

what can metapopulation structure allow? significance?

Answer 7

population persistence even when individual populations are doomed

Local populations can be renewed by colonists from other populations after going extinct

Question 8

what are the sinks and sources in source-sink dynamics?

Answer 8

sinks; populations in small habitat
patches that would go extinct

source; Migrants from ‘source’ populations ‘rescue’
these populations

Question 9

what are the prey and predator populations like when some prey colonize an empty island?

Answer 9

prey population low

predator population zero

Question 10

what are the prey and predator populations like when prey quickly grows toward carrying capacity?

Answer 10

more prey no predators

Question 11

what are the prey and predator populations like when Some predators arrive and reproduce rapidly?

Answer 11

large prey population small predator population

Question 12

what are the prey and predator populations like when predators drive prey to extinction?

Answer 12

predators population medium

prey population zero

Question 13

what are the prey and predator populations like when predators starve, the island is empty?

Answer 13

prey population zero

predator population zero

Question 14

patch dynamics similar to

Answer 14

population dynamics

Question 15

what to do to find patch dynamics

Answer 15

we track patch occupancy through time

Question 16

when do Populations within patches go extinct?

Answer 16

at some constant e

Question 17

what is the colonization of patches affected by? (4) ONER

Answer 17

number of currently occupied patches

the number of patches, the more patches the more colonizers

The fraction of empty patches

rate patches are getting filled up, as patches fill up, fewer patches to colonize

Question 18

colonization rate equation

Answer 18

cP(1-P)

Question 19

Levins patch occupancy model

Answer 19

dP//dt=cP(1-P)-eP

Question 20

at equilibrium what does Levin patch occupancy model equal?

Answer 20

zero

Question 21

why is local coexistence is impossible?

Answer 21

Say A always outcompetes B within a habitat patch

Question 22

what does global coexistence require? (3) ECDC

Answer 22

A must sometimes go extinct in a patch OR new patches must be created from time to time

B must be a better disperser than A
so B must be a “fugitive”, “tramp” ,” weedy”, opportunistic”, and “transient” species

A competition-colonization trade-off

Question 23

what are the ways a population can be driven to extinction? SCIA

Answer 23

Stochasticity

Competitive exclusion

through predator-prey interactions

allee effect(positive relationship between fitness and population density) at low-density

Question 24

Stochasticity

Answer 24

chance fluctuations in population numbers

Question 25

what stops populations from being driven to extinction (2)

Answer 25

Predation keeping competitive exclusion from going to completion

Non-equilibrial conditions, habitat patchiness, rescue-by-migration, variation in life-history strategy (competition colonization tradeoff)

Question 26

metacommunity

Answer 26

set of local communities that are linked by dispersal

Question 27

what determines the number of
species on an island? definitions of each? CEI

Answer 27

colonization: a species can arrive on an island from elsewhere

extinction: a species can go locally extinct on an island

In-situ speciation: a lineage can split in two on an island, but this is a very slow process

Question 28

what was MacArthur and Wilson’s theory of island biogeography? when is this theory ignored?

Answer 28

predict the number of species on an island from the island’s size and isolation (distance from mainland)

Ignored in-situ speciation;
only considered colonization and extinction to determine population size