1. Populations Population Genetics Population Growth
Interactions Among Populations
Ecological Succession

2. Population Genetics
A population is a group of individuals of the same species occupying the same habitat at the same time
The gene pool of a population is all of the different genes that occur within the population
A deep gene pool results when there is great variation within a population
A shallow gene pool results when there is little diversity in a population

3. Population Genetics
For a given trait the frequency of each phenotype can be calculated
The frequency of each genotype can be estimated
The frequency of each allele can be estimated

4. Population Genetics
The Hardy-Weinberg equilibrium predicts that allelic frequencies remain constant over time provided five conditions are met
A population at equilibrium is not evolving with respect to the trait
A population that has its equilibrium disturbed is evolving with respect to the trait

5. Population Genetics
Microevolution is the directional change in frequency of alleles over time
Change in allele frequencies can occur due to:
Genetic Drift: the reproductive success or failure of an individual in a small population

6. Population Genetics
Mutation: new mutations can add new alleles or change existing alleles that could be advantageous or disadvantageous
Gene Flow (Migration): Disproportionate movement of individuals into or out of a population

7. Population Genetics
Non random mating due to preferences based on inheritable characteristics
The founder effect decreases diversity in the population of descendents of a small founding population
The bottleneck effect decreases genetic diversity when a large population is reduced to a small population by selective pressure
Natural Selection is the result of any of the above factors

8. Population Genetics
Change in allelic frequencies can result in speciation
Speciation can occur if populations of the same species become reproductively isolated

9. Population Growth Measures of population growth include
Size: determined by census or sampling
Density: population size per unit area or volume
Per Capita Growth Rate: the growth of a population per individual (due to immigration, emigration, natality and mortality)
Growth Rate: the growth of a population over time

10. Population Growth Characteristics of populations include
Distribution (random, uniform or clumped)
Growth Curve : J-shaped (exponential) or S-shaped (sigmoidal)
Ecological Niche: the role played by a population in an ecosystem

11. Population Growth
Geographic Range: a region where a population can be found
Habitat: the physical conditions that support a population
Population Pyramid (Histogram): a graph representing the age and gender distribution of a population

12. Population Growth Reproductive Strategy: k or r selected strategies
Environmental Resistance: factors that limit population growth (density dependent or density independent)
Biotic Potential (Fecundity): maximum reproductive rate under ideal conditions

13. Population Growth
Tolerance Range: the minimum and maximum levels of an environmental factor that can support population growth
Law of the Minimum: of the number of essential substances required for growth, the one with the least concentration is the controlling factor
Open or Closed: an open population is influenced by immigration, emigration, natality and mortality (closed has no immigration or emigration)

14. Interactions Among Populations
All populations exist within a biological community such that populations must interact
Population interactions include:
Interspecific Competition: competition between two different species (-/-)
Gause’s Principle: no two species can occupy the same niche without one being reduced in numbers or being eliminated
Intraspecific Competition: competition among individuals of the same species(-/-)

15. Interactions Among Populations
Predation: A predator population feeds on a prey population (+/-)
Mimicry
Symbiosis: Two different organisms live in close association with each other
Parasitism (+/-)
Commensalism (+/0)
Mutualism (+/+)

16. Ecological Succession
Ecological succession is the progessive replacement of one community by another during the development of vegetation in an area
Primary succession refers to the occupation, by plant life, of an area not previously covered by vegetation
Secondary Succession refers to an area that was previously covered

17. Ecological Succession
Succession progresses from a pioneer community, through several seral stages to a climax community
As succession progresses biomass of the ecosystem increases
As succession progresses biodiversity increases and then declines when a climax community is reached