WCG L1

What is biodiversity?

The variety of ecosystems, species, populations and genetic diversity within and among populations

Why is biodiversity declining rapidly today?

Mainly because of human activities such as habitat loss overexploitation introduced species and pollution

What is meant by the “sixth extinction”?

The current mass extinction event driven primarily by human activities

Why is the current extinction crisis considered unusual?

Because extinction rates are much higher than natural background rates

Why is biodiversity important to conserve?

Because it provides bioresources (food = animals, plants), ecosystem services (clean air), aesthetic value and ethical value

What are ecosystem services?

Biological functions provided by ecosystems that benefit humans such as pollination nutrient cycling and water purification

What are bioresources?

Biological resources humans use such as food medicines fibres and timber

What are the four main human related causes of extinction?

Habitat loss

introduced species

overexploitation

pollution

Why do small populations have a higher extinction risk?

Because random processes have stronger effects in small populations

What is environmental stochasticity?

Random variation in environmental conditions such as rainfall, temperature, or food supply

What is demographic stochasticity?

Random variation in birth rates death rates and sex ratios

What is genetic stochasticity?

effects in small populations

– Loss of genetic variation – loss of adaptive potential

– Inbreeding depression – deleterious effects of recessive mutations

What is genetic diversity?

The amount of genetic variation present in a population

Why is genetic diversity important for population survival?

Because it allows populations to adapt to environmental change

What happens to genetic diversity in small populations?

It decreases due to genetic drift

What is genetic drift?

Random change in allele frequencies especially strong in small populations

What is inbreeding?

Reproduction between related individuals

What is inbreeding depression?

Reduced survival or reproduction caused by inbreeding

What is the extinction vortex?

A feedback loop:

small pop —> genetic drift + inbreeding

loss of genetic diversity —> low individual fitness + low pop. adaptability

lower reproduction + high mortality —> smaller pop —> REPEAT

What is a threatened species?

A species with a high risk of extinction in the near future

What is conservation genetics?

The use of genetic theory and techniques to reduce extinction risk in threatened species

What is the main goal of conservation genetics?

To preserve genetic diversity (90% in 100 yr) and evolutionary potential of species