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Extinction: Bad Genes or Bad Luck?

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Not to be confused with gradual evolutionary change that leads to the creation of a new species ... Black-footed ferret- eats mostly prairie dogs and pocket gophers ... – PowerPoint PPT presentation

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Title: Extinction: Bad Genes or Bad Luck?


1
Extinction Bad Genes or Bad Luck?
Defined- the complete death of a taxon
Not to be confused with gradual evolutionary
change that leads to the creation of a new species
Which is termed as Anagenesis
2
Possible Fates Over Time for Species A
Species A
Species D
3
Possible Fates Over Time for Species A
Extinction by demographic failure
Extinction by Genetic Swamping
Species X
Species X
4
Extinction as a Natural Process
Life as we define it has existed on earth for 4
billion years
Possibly as many as 4 million species on earth
today
Estimated that 50 billion species have lived on
earth
Thus, less than 1 in 1,000 species that have
lived on earth are alive today!
5
Characteristics of Extinction-Prone Species
1. Low reproduction rate
6
2. Species with specialized feeding habits
7
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8
Koalas- eat only leaves from certain species of
eucalyptus tree
9
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10
3. Species that feed at high trophic levels,
such as, Bengal Tiger or
11
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5. Limited or specialized nesting or breeding
area, such as Kirtlands Warbler which breed only
in burned over jack-pine forest stands in
Michingan, Minnesota and Canada
15
6. Found only in one place or region, such as
the elephant seal from the Pacific Coast or...
16
Unique island forms such as the Hawaiian
Honey-creepers including the O-O complex
17
7. Species with fixed migratory patterns,
including Whooping Cranes
18
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19
Gray Whale migration route
20
8. Species that are purported to prey on
livestock or people
Coyote
21
American Alligator
22
9. Unique behavioral patterns, such as Key Deer
and .
23
Social Facilitation in Passenger Pigeons
Remember- the Fraser Darling Effect
24
Population Size
25
10. Species with poor dispersal or colonizing
potential
Such as flightless birds, including the Dodo
26
Or island forms such the Aye-Aye
27
11. Species such as frugivores and nectivores
that exploit unreliable resources
Complex of Hawaiian Honeycreepers
28
12. Species that cannot tolerate habitat
disturbance such as forest interior bird species
Kentucky Warbler of the Southeastern North
America deciduous forests
29
Multiple Factors
Specialized feeding habits
Low reproductive potential
Unique island form
Poor dispersal potential
Cant tolerate disturbance
Found in only one place or region
30
Deterministic Processes and Decline to Extinction
Stresses that affect populations in direct,
detrimental ways by
Increasing mortality
And/or decreasing reproduction
31
Deterministic Processes and Decline to Extinction
1. Direct killing
Great Auk- killed for meat and oil
32
2. Introduced predators such as rats, cats and
mongoose
Hooded Warbler- ground nesting songbird in the
eastern United States
33
3. Exotic predators introduced accidently
12/14 bird species 2/3 bat species 6 lizard
species
Native of southeast Asia, Philippines, Indonesia
Arrived on Guam accidently, probably in a
shipment of fruit
34
4. Introduced species out-competing native
species for resources, thus driving them to
extinction.
Galapagos Rice Rat
35
5. Introduced species as vectors for disease
36
6. Genetic swamping
Mallard- drake
37
Mallard Hen
38
Mallard Group
39
Mallard
Mexican Duck
Black Duck
Mottled Duck
40
7. Habitat Disruption
41
Historic Whooping Crane Migratory Stop-over site
42
North American Farming Practices
43
Brown-headed Cowbird
A brood parasite formerly confined to the Great
Plains in association with Buffalo Herds
Female
Male
Brood Parasitism laying eggs in the nest of
another species
44
Female Cowbird laying an egg in a vireo nest
45
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46
Habitat Fragmentation
The breaking up of contiguous tracts of habitat
into smaller, not-connected patches
Accomplished in a variety of ways including
Results in creation of patches that are below the
minimum area needed for survival and reproduction
Concept of Species Area Curves- the illusive
figure 5.8 page 49
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