Global Patterns of Species Richness
Global Amphibian Diversity
Wallace’s hypotheses for higher species
diversity in the tropics:
1.
2.
3.
4.
5.
6.
7.
8.
9.
Productivity
Spatial heterogeneity; morphological diversity
High average rarity – no monocultures
Climatic constancy – little seasonal variation
Geological age
Special adaptations required for “harsh” environments
Greater competitive “balance” in tropics
Alternating competitive advantages
All niches filled – saturation of community
Early Island Biogeography
Island
Habitats in
Baltic Sea
Reptile and Amphibian Species Area Curve for Caribbean Islands
Habitat Islands
In the Great Basin
Top – Birds,
Bottom - Mammals
Species Richness related to Island Size
and Island Isolation
Species-Area Curves for Islands
S = cAz where:
S = number of species
A = area of island
c = constant for habitat type - forest, desert,
grassland
z = slope of the curve - predicted to be 0.263,
but actually varies with dispersal ability
An area of island will have fewer species than
equal sized area of continent
Ant species
On New
Guinea and
Nearby
Islands
The slope of the line plotted for species-area curve is
larger for species with poor dispersal abilities
Oceanic islands
birds - New Guinea islands
beetles - West Indies
land plants - Channel Islands
Habitat islands
birds - Andes paramo
birds - mtns of Great Basin
mammals - mtns of Great Basin
inverts -caves in West Virginia
z=0.22
z=0.34
z=0.37
z=0.29
z=0.165
z=0.326
z=0.72
Island Biogeography
Species Dispersal to Islands
Cape May Warbler on a Ship
Krakatoa pre-eruption
Looking at Volcano Rakata
Krakatoa mid-eruption
Map of Krakatoa pre-eruption
Landsat Image of Anak Krakatau
and Krakatau
Dan Simberloff and Mangrove Islands
Simberloff’s defaunation experiment on Mangroves
Simberloff’s defaunation experiment on Mangroves
Results from Simberloff’s Experiment
Islands recovered to pre-defaunation number of species, but only 30%
of original species resident on each island returned after defaunation.
Bracken
Fern
Bracken fern stand Australia
Number of species found on Bracken Fern
Professor Axel Meyer – Cichlid Man
Lake Malawi Cichlids
Adaptive radiation within cichlid lineages