Genetic diversity as related to mammalian extinction. A major goal is to learn how genetic diversity changes (if at all) as a species approaches extinction, which may well assist with conservation plans for endangered species. One approach would be to sample large percentages of global museum holdings for all recently extinct mammals for which reasonable numbers of individuals across a reasonable timeframe (multiple decades at least) are available. (Note that approaching diversity through time with museum collections is especially powerful because samples are usually dated to the nearest year, and commonly to the exact date and month.) Species meeting these criteria include approximately five Australian marsupials, the Caribbean monk seal, the Japanese sea lion, perhaps Steller's sea cow, two bat species, possibly the Falkland Islands wolf, and a handful of rodents. Pre-extinction patterns of diversity can be compared across unrelated mammals that have suffered global extinction. For example, is there any overwhelming shared signature of mtDNA diversity that precedes global extinction in a predictable manner across taxa? Or is this different for every species based on the unique conditions of its particular decline?

Documenting the spread of disease from invasive to native species. Dates of local (e.g. insular) or global extinction are known for many mammal species and populations with reasonable accuracy, as are dates of exotic introduction/invasion of certain species into novel landscapes. In some cases it is suspected that extinctions of certain native species have followed causally from introductions of certain invasive species (especially on islands), and that disease may be involved in some of these cases, but these types of claims generally remain anecdotal. The timing of the global decline of certain endemic insular rodent (and potentially other small mammal) lineages and the global spread of commensal rats offer many iterative, analogous cases for studying the spread of disease from invasive rats (with humongous global population sizes and greater exposure to a wealth of pathogens across time and geography) to comparatively 'naïve' and isolated endemic rodents with much smaller population sizes and less extensive historical exposure to disease. We predict that comparisons of metagenomes/bacteriomes/viromes sequenced from museum hair samples will be illuminating here.