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Flashcards in Maintaining populations in the wild Deck (56)
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31

How many populations of the grizzly bear are now in the US?

Six populations in four states due to the Western colonisation

32

What is the number of grizzly bears currently and past?

From 100,000 to 1,000

33

What is the effective population size of the grizzly bear and why?

25% because not all individuals can breed

34

How does this number of effective population affect the grizzly bear?

It can cause a loss in genetic variation

35

What is inbreeding depression?

The reduced fitness in a given population as a result of the breeding of related individuals

36

Why is inbreeding depression not a problem in large populations?

In large populations, individuals do not mate with close relatives

37

What is the result of inbreeding depression?

Weak or sterile offspring and expression of harmful genes

38

Where is inbreeding more likely?

In smaller populations

39

Why is inbreeding a cause for concern for rare species?

Threatens their survival

40

What is outbreeding depression?

Outbreeding depression is a scientific term that refers to when two distant relatives of the same species produce offspring less fit than themselves

41

What is the potential outcome from a loss of evolutionary flexibility?

Extinction

42

How can variability in climate effect population sizes?

A wet year could increase plant growth and therefore increase herbivores which in turn could increase carnivores

43

How can natural catastrophes affect population sizes?

It can eliminate populations

44

Variability in climate is more likely to affect what population sizes?

Small population sizes, they are more vulnerable

45

Explain the Vortex Effect

Natural disaster may lower population size. This may lead to inbreeding depression. Meaning more vulnerable to extinction.

46

Give an example of a species that become victim to the Vortex Effect

Greater Prairie Chicken

47

Give the population in 1933, and the population in 1989

25,000 in 1933 to 50 in 1989.

48

What was the reason for the Greater Prairie Chickens decline?

Conversion of prairie to farmland

49

As a result of translocation of male Greater Prairie Chickens to larger populations what happened?

Increased egg hatching success, and increase in genetic diversity

50

Rarity is a natural phenomenon based on what three parameters?

Geographical range
Habitat specificity
Population sizes

51

In terms of the IUCN Red List what does extinct in the wild mean?

Extinct in the wild!

52

In terms of the IUCN Red List what does critically endangered/ endangered mean?

In danger of extinction if causal factors of decline continue

53

In terms of the IUCN Red List what does vulnerable mean?

Species that are likely to become endangered if casual factors of decline continue

54

In terms of the IUCN Red List what does near threatened mean?

Populations that are not endangered of vulnerable, but are at risk

55

In terms of the IUCN Red List what does least concern mean?

Abundant species

56

How does the IUCN Red List determine which species goes into which category?

By measurements of species decline and population viability