The vertebrate fossils recovered as part of the Tongass Caves Project have enormous significance and have filled a crucial geographical gap in the study of the North American fauna. Their excavation has been an exciting project featuring one breakthrough after another. Southeast Alaska, once thought to be an insignificant place that only recently became colonized by mammals, now appears to have been an Ice Age refugium and possibly a corridor for coastal colonization.
Island biogeography is a most interesting topic.
The study of variation among island populations was one of the key factors that led Charles Darwin to his theory of evolution. Since Darwin's time, mathematical models have been developed to analyze island diversity in order to determine modes of colonization and rates of extinction. Island systems which have a predictable diversity based on island size and distance from the mainland are said to be in equilibrium, suggesting a constant colonization rate. Systems lacking such equilibrium are thought to represent relict distributions from some former period when colonization was easier. The Alexander Archipelago poses an even more complex puzzle that is only beginning to be elucidated.