Lecture 22 Movement & Dispersal

Question 1

Population Dynamics

Answer 1

Population dynamics describe the spatial and temporal variation in
population size as a result of abiotic and biotic conditions

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Question 2

Population Dynamics: Predator-Prey

Answer 2

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Question 3

Lynx and Hare

Answer 3

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Question 4

Movement & Dispersal

Answer 4

• Dispersal shifts spatial
  distributions of individuals in
  time and space
• Emigration: individuals leave
• Immigration: individuals arrive
• Movement between
  populations maintains gene
  flow in metapopulations
• Distance travelled depends on
  density of surrounding
  subpopulations and habitat
  suitability

Question 5

Dispersal

Answer 5

• Emigration
  increases when
  population
  becomes crowded
• Allows escape
  from competition
  and aggression
• May offer new
  opportunities for
  mates and
  resources
• Passive dispersal
  involves gravity,
  wind, water, or
  animals to move
  organisms
• Dispersal distance
  depends on the
  dispersal agent

slide 8-12

Question 6

Movement & Dispersal

Answer 6

Mobile animals can be
stimulated to disperse
because of:
* Crowding
* Temperature changes
* Food availability /
quality
* Photoperiod

slide 13-14

Question 7

Migration: Seasonal Patterns

Answer 7

slide 18-24

Question 7

Migration

Answer 7

• Migration is the intentional,
  directional movement of animals
  between two regions of habitats
• May be daily or seasonal
• How?!
• Position tracking relative to sun and
  stars
• Sensing of magnetic fields
• Why?!
• Better resources
• Milder climate
• Safer for raising offspring

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Question 7

Migration: Daily Patterns

Answer 7

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Question 7

Island Equilibrium Model

Answer 7

slide 27-29

Question 7

Population Expansion

Answer 7

• Dispersal can result in shift or expansion of species range
• Introduced and invasive species (more next week)
• Climate change (more in two weeks)

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Question 8

Population Dynamics

Answer 8

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Question 9

Island Equilibrium Model: Island Size

Answer 9

Smaller islands = higher extinction
* have fewer resources & less habitat diversity
* support smaller populations
(Also lower immigration)

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Question 10

Island Equilibrium Model: Distance

Answer 10

Closer islands = higher immigration
* are easier to get to
(Also lower extinction)

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Question 11

Island Equilibrium Model

Answer 11

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Question 12

Population Connectivity

Answer 12

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Question 13

Population Connectivity: Metapopulation

Answer 13

• Metapopulation: a population broken into
  sets of subpopulations connected by
  dispersal across an inhospitable matrix
• Dispersal among patches prevents regional
  extinction

An extension of island biogeography describing colonization and
local extinctions among a patch of habitats: same rules apply!

slide 37-38

Question 14

Population Connectivity

Answer 14

Different species respond to landscape features differently!

Landscape connectivity: how much the landscape facilitates or impedes movement

slide 39-40

Question 15

Population Connectivity & Genetic Diversity

Answer 15

Genetic diversity can tell us how recently &
how much subpopulations are interacting

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Question 16

Population Genetics

Answer 16

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