The biogeography of endemism, age, and area

• Ted Case

Abstract
ABSTRACT

I will be working on three projects during my sabbatical stay at NCEAS.

I am very interested in the quantitative relationship between the
degree of habitat destruction (and deterioration) and species loss and gain
in defined geographic areas. For example, if 50% of native habitat is
converted to man-modified habitats on an island, what proportion of native
species are expected to become extinct? How will the success of exotic
species be affected? Previous work shows that this is going to be related
to overall island area, the degree of endemism of the fauna, and the
habitat diversity on the island. I have accumulated bird and reptile
faunas and geographical information on about 70 regions of the world,
mostly insular, and I have already published on some of the relationships.
For example, statistically, there is a strong association with the degree
of historical extinction and the degree of endemism in these taxa.
Additionally, the number of introduced species of land birds is closely
related to the number of extinct species. At NCEAS I will attempt to
understand these relationships at a more mechanistic level, by:

1) Developing a model to explain the geographic roots of endemism.

2) Determining the relationship between island size, isolation, per cent
endemism, and habitat diversity.

3) And, finally merge these models to predict the expected relationship
between habitat destruction and island features (area, isolation, endemism)
and relate these predictions to historical observations in the data set.

Secondly, I would like to spend more time working on ongoing projects that
I am involved in at the Center. Mike Goodchild, Carolyn Hunsaker, Mark
Friedl, and I will be editing a book based on the ongoing working group
entitled "PERSPECTIVES ON UNCERTAINTY IN SPATIAL DATA FOR
ECOLOGICAL MODELS".

Robert Holt and I will also be writing chapters stemming from the ongoing
working group on "Species Borders". Here I am also interested in doing so
primary synthetic work on the subject. In particular, I think it would be
interesting to imbed models of character displacement, which Mark Taper
and I developed earlier, onto an explicit spatial dimension. The questions are,
how is the possibility of escape in space going to affect the likelyhood and
degree of character displacement? And how does the possibility of character
displacement modify the evolution of species geographic range limits?

Ted J. Case
Professor of Biology