Biodiversity Crisis

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Biodiversity Crisis

• Two centuries of warnings from scientists of
  anthropogenic losses of species
• Since 1600s
• 129 species of birds
• 83 species of mammals
• 21 species (including 100 subspecies) reptiles
• 7 species amphibians

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Biodiversity Crisis

• Freshwater
• 40 species N. American fish during latter part of
  20th century
• Worldwide 20 fish in jeopardy or extinct
• Molluscs 7 of 297 recognized species presumed
  extinct another 65 endangered, threatened, or
  candidates for listing
• Plants last 400 yr, 600 species (176 in US)

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Number of Plants Globally
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Percent Fish Threatened
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Examples from Major Faunal Groups
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Linnaean Shortfall

• 1.7 million species described
• Estimated 5 30 million species
• Species will go extinct before are known to
  science

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Hotspots of Diversity

• Patterns of diversity and endemism provide clues
  for locating rare and endangered species.
  Questions
• What are the locations of hotspots for particular
  taxonomic groups?
• Do hotspots of taxa overlap?
• Example Endemic bird areas (EBAs) where range
  of at least two restricted-range species present.
  Their pattern is not random

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Is evidence for overlap of some groups


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Overlap of hotspots for fish, coral, lobsters,
and snails
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Prehistoric Extinctions

• Permian
• Cretaceous
• Migration and radiation following linkages
  between continents
• Formation of Pangaea
• Laurasia
• Great American Interchange
• Pleistocene (climate-driven, at least partly)

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Prehistoric Extinctions last 2 million years

• New world megafauna and human colonization
• Aboriginal application of fire in Australia and
  Americas broad range of plants and animals
• Africa exception to human effects species there
  evolved with humans and were able to adapt

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Recent Historical Record of Extinctions

• Insular extinction rate greater than continental
  rate

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Human-related Species Introductions

• Similar to continental convergences?
• Most common species common rabbit, cats, rats,
  house mice, pigs, cattle, goats, dogs
• Part of naturalization bring along a piece of
  home
• Most common carnivores (19) and artiodactyls
  (31 deer and related ungulates)
• Only represent 7 of fauna

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Human-related Species Introductions

• Mammal introductions to islands 118 species, 30
  families, and 8 orders
• Birds 212 species, 46 families, and 16 orders
• Australia has received most introductions per
  unit area for continents

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Habitat Fragmentation

• Breaking up of large parts of ecosystems for
  agriculture and urbanization
• Puts species in peril (details later)
• Hardest hit are tropical rain forests
• 7 Earths surface 50 species
• Madagascar 7 left
• Brazil Coastal Forest 1 left
• Singapore - lt1

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Causes of plant endangerment in US
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Ecological Effects of Fragmentation

• Reduction in total area, resources, and
  productivity of native habitats
• Increased isolation of remnant fragments and
  their local populations
• Significant changes in environmental
  characteristics of fragments, including solar
  radiation, wind, and water flux

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Stages of Biotic Collapse

• Stage 1 Initial exclusion some populations not
  included in remnant patches
• Stage 2 Extirpation due to lack of essential
  resources
• Stage 3 Perils associated with small populations
  genetic, demographic, stochastic problems

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Stages of Biotic Collapse

• Stage 4 Deleterious effects of isolation
  rescues by recruitment diminished
• Stage 5 Ecological imbalances loss of
  interactions (mutualism, parasitism, commensals)
  and biotic regulation (predation, competition)

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Biogeography of Climate Change

• Periods of warming from greenhouse gas
  accumulation before
• Difference is time over which it took place
• Human activities have greatly escalated
  greenhouse gas concentrations over last 50 yr
• Temp Projected increase 1.5 6C mean 2.5C
  0.7C since 1860
• End of Wisconsin Temp incr. 4.5C over 5000 yr
  (lt1C/1,000 yr) raised sea level 100 m

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Pattern of CO2 last 160,000 yr
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Changes in Greenhouse Gases
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Change in Global Temperatures (2000-2003)
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Departures from Average Temperature
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Biogeography of Climate Change

• Biogeography helps predict changes in
  distributions, corridors, geographic isolation of
  species, and extinctions
• Range change IS NOT just going to be temperature
• Other abiotic factors must be in place
• Just as in other events, e.g., Pleistocene, must
  be able to disperse and adapt to new conditions

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Changes in Elevational Gradients of Habitat
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Species-area relationship to predict change in
species richness of boreal mammals in isolated
mountain ranges of Great Basin (3C increase
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Freshwater Biota

• 4C increase in temperature
• Increase mean annual runoff 9 21
• Shifts temporal runoff patterns (increase
  precipitation winter and spring, decrease summer
  and fall)
• Lead to changes in water quality

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Marine Biota

• Latitudinal and vertical shifts in water
  temperature warm waters toward poles and greater
  depths
• Alters horizontal and vertical mixing of currents
• Salinity near equator and higher latitudes will
  decrease (increased precipitation in those
  regions)

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Connectivity and Corridors

• Redistribution and loss of habitats will create
  new barriers for dispersal
• Will also tend to increase isolation of patches
  in increasingly fragmented habitats (refer to
  human effects earlier)

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Tools of Biogeography Used to Create Models and
Provide Answers to These and Other Conservation
Questions