Population size and conservation

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Questions and Answers

What effect does inbreeding have on the expression of genes?

It reduces the chance of expressing rare genes.

It only affects dominant genes.

It increases the likelihood of expressing rare or recessive genes. (correct)

It eliminates deleterious genes.

Which species faced a significant demographic bottleneck in the past?

Northern elephant seal

Cheetah (correct)

Barred owl

Northern spotted owl

What is a metapopulation?

A population that exclusively inhabits one habitat type.

A population with no gene flow.

A group of individuals that only reproduce among themselves.

Several populations that have regular or occasional gene flow. (correct)

Which habitat type produces surplus individuals for migration in a metapopulation?

Source habitat Signup and view all the answers

What is a significant result of the lack of genetic diversity in male cheetahs?

Low survival rate for offspring Signup and view all the answers

Why do northern elephant seals not seem to suffer from problems linked to genetic similarity?

Only the most fit individuals reproduce. Signup and view all the answers

What is a primary factor conservation biologists consider for species survival?

Population dynamics Signup and view all the answers

What characteristic defines a sink habitat for species like the spotted owl?

Mortality exceeds birth rates. Signup and view all the answers

What does the equilibrium theory of island biogeography propose affects biodiversity on isolated islands?

Rates of colonization and extinction Signup and view all the answers

Which factor contributes to the higher extinction rates on small islands?

Smaller populations susceptible to disasters Signup and view all the answers

What term describes the stability in genetic variation within large populations?

Hardy-Weinberg principle Signup and view all the answers

Which process accounts for the gradual changes in gene frequencies due to random events?

Genetic drift Signup and view all the answers

What is referred to as the founder effect in population genetics?

Dominance of traits from a small, colonizing population Signup and view all the answers

What could limit species adaptability and survival in small populations?

Genetic diversity reduction Signup and view all the answers

Which scenario best describes a demographic bottleneck?

A sharp decrease in population and genetic diversity due to a catastrophic event Signup and view all the answers

What is a significant concern for population biologists regarding island species like birds in Hawai’i?

Loss of species due to extinction events Signup and view all the answers

Study Notes

Island Biogeography and Biodiversity

Small, remote islands generally have lower biodiversity than larger islands.
MacArthur and Wilson's equilibrium theory links island diversity to colonization and extinction rates.
Colonization rates depend on proximity to source populations (e.g., continents, other islands).
Extinction rates depend on island size, which influences population size and vulnerability to environmental events.

Genetic Diversity in Small Populations

Genetic variation maintains stability in large, stable populations (Hardy-Weinberg principle).
Random environmental changes can cause shifts in gene frequencies (genetic drift).
Genetic drift becomes significant in isolated, small populations due to limited genetic variation.
Founder effect: Reduced genetic diversity from a small initial colonizing population.
Demographic bottleneck: Loss of genetic variation due to a catastrophic event.
Inbreeding: Mating of closely related individuals, increasing expression of recessive genes.
Genetic diversity loss can effect adaptability and reproduction for the species.

Cheetahs and Northern Elephant Seals

Cheetahs are a prime example of a species affected by genetic bottlenecks, with low fertility, abnormal sperm, and reduced offspring survival, due to nearly identical genetic make-up.
Northern elephant seals, despite near extinction, recovered and have almost identical genetic profiles.
The survival of these species can depend on selected populations who are the most fittest or where no harmful genes are present.

Minimum Viable Population Size

Biologists use island biogeography principles to estimate minimum viable population size that is necessary for long-term survival in endangered species.

Metapopulations

A metapopulation is a group of populations across geographically separate areas that interact.
Gene flow between these groups is possible via corridors (migration routes).
Northern Spotted Owls are an example of organisms that have been historically interdependent.
"Source" habitats have higher birth rates than death rates and produce the individuals to migrate and populate other regions.
Habitats called “sink” regions have birth rates lower than death rates.

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Description

Explore the concepts of island biogeography and genetic diversity in small populations. This quiz covers key theories such as MacArthur and Wilson's equilibrium theory, the Hardy-Weinberg principle, and factors affecting colonization and extinction rates. Test your knowledge on how these concepts interact to influence biodiversity.