Ecology of South Florida (EVR 3013) LECTURE 14
INTRO ECOLOGY II
ISLAND (& FLORIDA) BIOGEOGRAPHY
POSSUM
Many words one could use
To talk about the 'possum
Giant rat, marsupial,
But certainly not awesome.
When it comes to brains
This beast is quite wanting.
Crossing highways at night,
proves to be daunting.
Playing 'possum may fool an old hound,
Likewise a bobcat or sailor,
But the strategy will always fail
With speeding tractor trailers.
G.W. Hunter (1997)
I. ISLAND BIOGEOGRAPHY
A. Authors
MacArthur and Wilson (1967) based on work by Preston (1962)
B. Basic theory
- Species diversity is a balance between immigration and extinction
- Immigration rates decrease as the number of species increases
- Immigration rates are higher on near islands than on far islands
- Immigration rates are higher on large islands than on small islands
- Extinction rates are higher on small islands than on large islands
C. Equilibrium model
1. S = I - E
2. Near islands vs. far islands
3. Large islands vs. small islands
D. The Numbers
Quantitative expression of the theory--Species-Area relationship
S = CAz
log S = log C + zlogA
S = number of species
C = taxon and site specific constant
A = area of an island
Z = exponent ranging from 0.24 - 0.33
E. Examples
1. Orchids in the Bahama Islands
2. Mammals on Great Basin Mountain Tops
3. Herps in the West Indies
F. Fragmentation
Fragmentation occurs when a large expanse of habitat is transformed into a number of smaller patches of smaller total area, isolated from each other by a matrix of habitats unlike the original (Wilcove et al. In M. Soule 1986)
G. 90/50 rule
II. FLORIDA BIOGEOGRAPHY
A. Plants
1. Florida
300 species of native trees, 3500 of vascular plants (Fernald et al. 1992)
2. S. Florida
1,647 species in 177 plant families (Long 1974)
B. Birds
ca. 440 species
C. Mammals (non-marine)
63 species, 40 in southern Florida
D. FW Fish
50 species
E. Reptiles and amphibians
| Category | State | S. Florida | Exotics |
|---|
| | species | varieties | species | varieties | species | varieties |
|---|
| Frogs | 31 | 39 | 19 | 22 | 4 | 4 |
|
| Salamanders | 25 | 34 | 7 | 10 | 0 | 0 |
| Crocs | 3 | 3 | 3 | 3 | 1 | 1 |
| Turtles | 24 | 48 | 19 | 31 | 1 | 1 |
| Lizards | 36 | 45 | 31 | 38 | 19 | 19 |
| Snakes | 45 | 86 | 34 | 49 | 1 | 1 |
| Total | 164 | 255 | 110 | 153 | 26 | 26 |
F. Patterns in Florida
1. Peninsula Effect
G. Gaylord Simpson , peninsula had fewer species than an equivalent mainland area, exhibiting a gradient of diversity which decreases toward the tip.
2. Herpetofauna
Means & Simberloff (1987) suggest that for herpetofauna the cause was the decrease in topographic and habitat diversity.
3. Umbilicus Effect
Diamond & Gilpin (1983) no evidence in FL, e.g., marshes in Southern FL.
4. Habitat islands
scrub
III. FLORIDA BIOTA XI: ANIMALS (invertebrates)
LECTURE 15: FLORIDA BIOTA REVIEW
PELICAN
A funny bird is the pelican
It's beak can hold more than its belly can.
But I don't know how the hell he can.
Back to start, Back to lecture 10, 11, 12, 13, On to lecture16, 17, 18, 19
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