9807045 YODER The carnivorous mammals of Madagascar have not been studied as extensively as other mammals on this island, yet are an important component of this unique fauna. How many times have carnivores invaded the island? How did they get there? From where did they come? Have any Madagascar carnivores ever migrated back to mainland areas? An understanding of the history (phylogeny) of Madagascar carnivores should help answer these and other questions about the biology and distribution of these animals. In this research, Anne Yoder and her colleagues John Flynn and Michael Nedbal will acquire and analyze DNA sequence data, from two mitochondrial genes and portions of two nuclear genes, collected from the species of Madagascar carnivores. From these data, the historical (phylogenetic) relationships of these carnivores will be reconstructed; the analysis will include carnivore species inhabiting other places that are presumed to be the closest relatives of the Madagascar carnivores, and thus may belong to lineages from which Madagascar carnivores appeared. In some cases, DNA sequence data can be used as a "molecular clock" to estimate dates for major events. The carnivore data will be evaluated to see if such estimations are appropriate, and if so, then geologic dates for carnivore colonization(s) of Madagascar will be proposed. The results of these investigations will become increasingly important as more is learned about other lineages of Madagascar's terrestrial vertebrates. If, for example, it is found likely that different groups appeared at widely spaced intervals and without obvious patterning to the intervals, then the best explanation for how Madagascar became populated with animals would be that it was haphazard; founders arrived on fallen logs or other "rafts" washed up at irregular intervals on the island's shore. If, on the other hand, all groups are estimated to have appeared within a relatively short time period, then a less random mechanism for populating Ma dagascar, likely tied to geological events, would be favored. For example, a discrete interval for animal arrival on Madagascar coupled with geological evidence for a chain of islands between Madagascar and another land mass would suggest that the animals "hopped" among these islands to colonize Madagascar.
