1. Climate and Biomes
Evolution and Adaptation
Population Ecology

2. Attributes of Populations
Population Ecology
Attributes of Populations
- Population: A group of potentially interbreeding organisms at the same time and place, that share a common gene pool.
- Population size : number of individuals
- Population Growth Rate: change in number over time, as a function of
(birth +immigration)- (death + emigration)
- Population density : number per unit area
- Range/distribution: geographic area over which the individuals are dispersed.
- Population Structure:
- age class structure
- sex ratio
- genetic structure
- spatial structure (pattern of how individuals are distributed through the range)

3. Population Ecology
Attributes of Populations
Distributions
A. Determining Factors
1. Environmental Tolerance – the Niche Concept

4. Attributes of Populations Distributions A. Determining Factors
Population Ecology
Attributes of Populations
Distributions
A. Determining Factors
1. Environmental Tolerance
Realized and fundamental niches
Zones of optima, tolerance, intolerance
soil moisture
temperature
performance

5. Attributes of Populations Distributions A. Determining Factors
Population Ecology
Attributes of Populations
Distributions
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal

6. 1. Environmental Tolerance
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration

7. 1. Environmental Tolerance
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
4. Changes thru Time: Climate Change

8. 1. Environmental Tolerance
A. Determining Factors
1. Environmental Tolerance
2. Barriers to Dispersal
3. Changes thru Time: Seasonal Migration
4. Changes thru Time: Climate Change
Changes in elevational range
cooler
warmer

9. Craig Moritz,1,2. James L. Patton,1,2 Chris J. Conroy,1 Juan L
Craig Moritz,1,2* James L. Patton,1,2 Chris J. Conroy,1 Juan L. Parra,1,2 Gary C. White,3 Steven R. Beissinger1, Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:

10. Craig Moritz,1,2. James L. Patton,1,2 Chris J. Conroy,1 Juan L
Craig Moritz,1,2* James L. Patton,1,2 Chris J. Conroy,1 Juan L. Parra,1,2 Gary C. White,3 Steven R. Beissinger1, Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:

11. 1. Correlates with Niche Parameters – greatest at center of range
B. Population Density
1. Correlates with Niche Parameters – greatest at center of range
Density of Dickcissel, a prairie songbird

12. B. Population Density 2. Habitat Selection
Fretwell – Lucas model of habitat selection (1972)

13. 3. Maintenance of Marginal Populations
B. Population Density
3. Maintenance of Marginal Populations
Why don’t these adapt to local conditions?

14. C. Modeling the Spatial Structure of Populations
1. Metapopulation Model
Subpopulation inhabit separate patches of the same habitat type in a “matrix” of inhospitable habitat..
- immigration causes recolonization of habitats in which population went extinct. So, rates of immigration and local extinction are critical to predicting long-term viability of population.

15. C. Modeling the Spatial Structure of Populations 2. Source-Sink Model
Subpopulations inhabit patches of different habitat quality, so there are ‘source’ populations with surplus populations that disperse to populations in lower quality patches (‘sinks’).

16. C. Modeling the Spatial Structure of Populations 3. Landscape Model
Subpopulations inhabit patches of different habitat quality, so there are ‘source’ populations with surplus populations that disperse to populations in lower quality patches (‘sinks’). However, the quality of the patches is ALSO affected by the surrounding matrix… alternative resources, predators, etc. And, the rate of migration between patches is also affected by the matrix between patches… with some areas acting as favorable ‘corridors’

17. III. Adaptation Natural Selection Trade-Offs Components of fitness?
- probability of survival
- number of offspring
- probability that offspring survive

18. III. Adaptation Trade-Offs 2. Relationships with Energy Budgets
METABOLISM
GROWTH
SURVIVAL
METABOLISM
REPRODUCTION
REPRODUCTION

19. III. Adaptation Trade-Offs
3. Trade-offs Between Survival and Reproduction
Maximize probability of survival
Maximize reproduction
GROWTH
METABOLISM
GROWTH
REPRODUCTION
METABOLISM
REPRODUCTION

20. III. Adaptation Trade-Offs
3. Trade-offs Between Survival and Reproduction
European Kestrels

21. III. Adaptation Trade-Offs
3. Trade-offs Between Survival and Reproduction
Cox, R.M., and R. Calsbeek Severe costs of reproduction persist in Anolis lizards despite the evolution of a single-egg clutch. Evolution 64:

22. III. Adaptation Trade-Offs
3. Trade-offs Between Survival and Reproduction
- Suppose the probability of adult survival is low for other reasons?
Can wait
Can’t wait

23. III. Adaptation Trade-Offs
3. Trade-offs Between Survival and Reproduction
- Suppose the probability of adult survival is low for other reasons?
Can vary within a species in different environments: Guppies

24. III. Adaptation Trade-Offs
4. Trade-offs Between # offspring and offspring survival
METABOLISM
REPRODUCTION
REPRODUCTION
METABOLISM
A few large, high prob of survival
Lots of small, low prob of survival

25. III. Adaptation Trade-Offs
4. Trade-offs Between # offspring and offspring survival – Lack Hypothesis
Again, diminishing returns

26. III. Adaptation Trade-Offs
4. Trade-offs Between # offspring and offspring survival – Lack Hypothesis
Varies within a species under different environmental conditions: Guppies

27. III. Adaptation Trade-Offs Timing 1. First Age of Reproduction
As lifespan increases, selection favors a delayed first age or reproduction

28. III. Adaptation
Trade-Offs
Timing
Life History Strategies

29. IV. Extinction
Causes
environment changes too quickly for a population to adapt.
- climate changes (abiotic environment can’t be tolerated)
- population reduced in size
- food sources become depleted (competition from other
organisms or habitat reduction)
- predation (from humans?) increases (death rate increases)
- mating behavior or mating season disrupted, or
encountering mates becomes rare
- subpopulations can’t migrate: extinction of local populations is greater than the rate of recolonization from another population; usually because of habitat changes in between.

30. Degree of patch isolation affects colonization probability
Balance between colonization rate from occupied patches, and extinction rate in patches.
Degree of patch isolation affects colonization probability

31. Greater Patch area means more resources, larger populations, and lower e
Low e/c
Larger patches means lower e,
higher c
p = 1 – (e/c)
High e/c
Closer patches mean higher c, lower e (rescue effect)

32. Why is this important?

33. Why is this important?

34. Why is this important?

35. Why is this important?

36. These are the large intact pieces of natural biome left…

37. IV. Extinction Causes B. Solutions - Maintain environmental conditions
- Keep large, intact, well-connected habitats.
- Reduce the number of introduced species that may be competitively superior to local specialists