Extinction, Variations in Population

AP CLASSROOM

Extinction

Disappearance of a species, such that no future generations will naturally populate the Earth

Extinction rates from ecological stress

Occur on a large scale and wipe out large numbers of species at one time, caused by catastrophic changes to an ecosystem: rising sea levels, volcanic eruptions, species diversity decreases

Human activity can drive catastrophic ecosystem change

• Habitat loss

• Climate Change

• Habitat degradation

• Pollution

• Poaching

• Invasive species

Speciation

process by which organisms become reproductively isolated and new species form

• High Species biodiversity result from high levels of speciation and low levels of extinction

• Low species biodiversity result from low levels of speciation and high levels of extinction

Niche

describes the role an organism plays within its environment, roles include: producer, decomposer, consumer

• When species goes extinct, it leaves an open niche for another species to occupy

Variation

different combinations of alleles(genotypes) and phenotypes found in a population

• Results from random mutation and crossing over during meiosis

• genotypes, in combination with environmental factors determine an individual’s phenotype

Genetic diversity

influences a population’s ability to respond to changes in the environment

Diverse populations have individuals with adaptations

These adaptations makes individuals more likely to withstand new environmental pressures and catastrophic geological events

Deleterious traits

Reduce the chance of survival

Adapative traits

Increase the chance of survival