Kent Holsinger

Kent Holsinger

Abstract

Genetics and Extinction in Fragmented Populations

The small populations that remain in habitat fragments may tend to lose their genetic diversity because of their small size. But many populations are naturally patchy and small. Fragmentation will affect the genetic structure of such populations far less than it will affect that of populations that are widespread and continuously distributed.

Fragmentation enhances loss of diversity when it inhibits the exchange of genes among populations. But it may increase the exchange of genes if the matrix separating populations from one another is not a significant barrier to dispersal. Studies of a dioecious orchid in central Panamá show that small populations found on islands isolated by construction of the Panamá Canal have a genetic structure similar to populations remaining in intact forest. Estimated rates of gene dispersal suggest that these populations remain well-connected.

Molecular markers, like allozyme or microsatellite loci, provide interesting data on gene dispersal among populations, but it is often difficult to discern how to apply these data to conservation problems. The pattern of population differentiation for traits is greatly affected by the type of selection to which those traits are subject. Populations may either be substantially more differentiated or substantially less differentiated than molecular marker data would suggest .

Biography

Kent Holsinger's research encompasses three broad areas: the evolution of plant reproductive systems, the genetics of geographically structured populations, and the application of basic biological principles to conservation problems. He received a Ph.D. from Stanford University in 1982 and joined the faculty of the University of Connecticut after post-doctoral studies at the University of California, Berkeley and the University of California, Davis. He has served on scientific review panels for the National Science Foundation, the Environmental Protection Agency, and the National Institutes of Health. He is Chair of the Board of Directors for the Connecticut State Museum of Natural History, Vice-Chair for Science and Stewardship of The Nature Conservancy Connecticut Chapter, and a member of the editorial board for Conservation Biology.

Relevant Publications

Holsinger, K. E., and P. Vitt. 1997. The future of conservation biology: what's a geneticist to do? In The ecological basis of conservation: heterogeneity, ecosystems, and biodiversity, ed. S. T. A. Pickett, R. S. Ostfeld, M. Shachak, and G. E. Likens, pp. 202-216. Chapman and Hall, New York, NY.

Holsinger, K. E., R. J. Mason-Gamer, and J. Whitton. 1999. Genes, demes, and plant conservation. In Genes, species, and the threat of extinction: DNA and genetics in the conservation of endangered species, ed. L. F. Landweber and A. P. Dobson, pp. 23-46. Princeton University Press, Princeton, NJ.

Holsinger, K. E. 1999. Analysis of genetic diversity in geographically structured populations: a Bayesian perspective. Hereditas 130:245-255.

Holsinger, K. E. 2000. Demography and extinction in small populations. In Genetics, demography, and the viability of fragmented populations, ed. A. Young and G. Clarke, pp. 55-74. Cambridge University Press, Cambridge.

<<Back to Presenters page