What Makes Populations and Species Vulnerable? Brook Milligan - - PowerPoint PPT Presentation

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What Makes Populations and Species Vulnerable? Brook Milligan Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu Fall 2009 Brook Milligan What Makes Populations and Species Vulnerable? Rarity What

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What Makes Populations and Species Vulnerable?

Brook Milligan

Department of Biology New Mexico State University Las Cruces, New Mexico 88003 brook@nmsu.edu

Fall 2009

Brook Milligan What Makes Populations and Species Vulnerable?

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Rarity

What makes populations and species vulnerable?

Brook Milligan What Makes Populations and Species Vulnerable?

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Rarity

What makes populations and species vulnerable? Rarity But . . .

Brook Milligan What Makes Populations and Species Vulnerable?

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Rarity

What makes populations and species vulnerable? Rarity But . . . Many types of rarity exist Examples of rarity

Argyroxiphium macrocephalum (Haleakala silversword): limited to Haleakala Volcano, Maui, Hawaii, but very common within crater Setaria geniculata (knotroot bristlegrass): distributed from Massachusetts to California, south to Argentina and Chile; not selective regarding habitat, but everywhere sparse; 2 specimens in NM (Hidalgo and Do˜ na Ana Counties)

Brook Milligan What Makes Populations and Species Vulnerable?

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Dimensions of Rarity

Geographic distribution

narrow wide

Habitat requirements

restricted broad

Local population size

everywhere small somewhere large

Brook Milligan What Makes Populations and Species Vulnerable?

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British flora survey

160 species categorized by experts Geographic Distribution Wide Narrow Habitat Specificity Habitat Specificity Local Population Size Broad Restricted Broad Restricted Somewhere large 58 (36%) 71 (44%) 6 (4%) 14 (9%) common Everywhere small 2 (1%) 6 (4%) 0 (0%) 3 (2%)

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity

narrow geographic range

ne or a few populations

small population size specialized niche requirements restriction to rare habitat low population density

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity

large home range large body size ineffective dispersers

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity Direct human exploitation

subject to human hunting or harvesting

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity Direct human exploitation Correlated effects of human-induced habitat alteration

aggregate permanently or temporarily characteristic of stable, pristine environments no prior contact with humans

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity Direct human exploitation Correlated effects of human-induced habitat alteration Evolutionary indications

low genetic variability related to extinct or threatened species

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity Direct human exploitation Correlated effects of human-induced habitat alteration Evolutionary indications Complex habitat requirements

seasonal migrants

Brook Milligan What Makes Populations and Species Vulnerable?

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Factors inreasing vulnernability

Rarity Correlates of rarity Direct human exploitation Correlated effects of human-induced habitat alteration Evolutionary indications Complex habitat requirements Immediate indicators

declining population size

Brook Milligan What Makes Populations and Species Vulnerable?

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International Union for the Conservation of Nature (IUCN) system

Categories of species Categories applicable to worldwide status

extinct extinct in the wild critically endangered endangered vulnerable near threatened least concern: include widespread and abundant species data deficient not evaluated

Additional categories applicable to regional status

regionally extinct not applicable: species not occuring naturally in a region or a rare migrant

Brook Milligan What Makes Populations and Species Vulnerable?

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Distribution of Species

Total IUCN Red List: 41,415 species Extinct: 785 species Extinct in the wild: 65 species Endangered and vulnerable: 16,306 species

critically endangered endangered vulnerable

Brook Milligan What Makes Populations and Species Vulnerable?

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Status of Major Taxonomic Groups

Endangered and vulnerable species Mammals: 25% Birds: 12.5% Amphibians: 33% Assessed plants: 70%

Brook Milligan What Makes Populations and Species Vulnerable?

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IUCN Evaluation criteria

Population size: total number of mature individuals Geographic range: total geographic area (B) currently alive (D) Population dynamics

bservable decline in numbers of individuals (A)

predicted decline in numbers of individuals (C) extinction probability: probability of extinction within a specified time or number of generations (E)

rarely used, but correlated with other factors how to calculate: PVA methods upcoming

Brook Milligan What Makes Populations and Species Vulnerable?

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IUCN Red List Criteria v3.1

A. Population

size

B. Geographic
C. Declining
D. Pop.
E. Extinction

Category reduction1 range

pop. size

size probability % km2 indiv. indiv. % Years Gen. Critically endangered ≥80–90 <10-100 <250 <50 ≥50 10 3 Endangered ≥50–70 <500–5,000 <2,500 <250 ≥20 20 5 Vulnerable ≥30–50 <2,000–20,000 <10,000 <1000 ≥10 100 Source: http://data.iucn.org/themes/ssc/redlists/RLcats2001booklet.html

1. Reduction over 10 years or 3 generations.

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Major agricultural pest in 1870s $200 million in crop damage between 1873 and 1877 in Colorado, Nebraska and other states

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Major agricultural pest in 1870s $200 million in crop damage between 1873 and 1877 in Colorado, Nebraska and other states “Greatest concentration of animals” (The Guinness Book of World Records) A swarm of Rocky Mountain locusts that flew over Nebraska on July 20–30, 1874, covered an area estimated at 198,000 square miles (almost twice the size of Colorado). The swarm must have contained at least 12.5 trillion insects with a total weight of 27.5 million tons.

Brook Milligan What Makes Populations and Species Vulnerable?

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Rocky Mountain Locust Distribution

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Current status Now (virtually?) extinct

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Current status Now (virtually?) extinct Historical causes Permanent and migratory phases of life cycle Waves of expansion from Rockies to plains Vulnerable because of habitat limitation in permanent breeding grounds: riparian regions in Rocky Mountains of Colorado

Brook Milligan What Makes Populations and Species Vulnerable?

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Case study: Rocky Mountain locust (Melanophus spretus)

Current status Now (virtually?) extinct Historical causes Permanent and migratory phases of life cycle Waves of expansion from Rockies to plains Vulnerable because of habitat limitation in permanent breeding grounds: riparian regions in Rocky Mountains of Colorado Conservation status Rare or not? Conserve or not?

Brook Milligan What Makes Populations and Species Vulnerable?