Climate and Biomes Evolution and Adaptation Population Ecology

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)

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

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

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

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

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

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

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. Beissinger1,4. 2008. Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:261-264.

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. Beissinger1,4. 2008. Impact of a Century of Climate Change on Small-Mammal Communities in Yosemite National Park, USA. Science 322:261-264.

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

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

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

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.

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’).

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’

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

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

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

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

III. Adaptation Trade-Offs 3. Trade-offs Between Survival and Reproduction Cox, R.M., and R. Calsbeek. 2010. Severe costs of reproduction persist in Anolis lizards despite the evolution of a single-egg clutch. Evolution 64: 1321-1330.

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

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

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

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

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

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

III. Adaptation Trade-Offs Timing Life History Strategies

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.

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

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)

Why is this important?

Why is this important?

Why is this important?

Why is this important?

These are the large intact pieces of natural biome left…

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