We do review some recent theoretical results, like the work of Mike Whitlock, and some new techniques that are being applied in field studies, like analyses of microsatellite variation in parents and progeny experiencing strong selection. However, it's really the empirical results that are new. Our paper pulled many of those studies together to point out that, contrary to general expectation, deleterious inbreeding effects are now evident in several field studies.

I think we did two things of significance. First, we laid out the basic theory of inbreeding in an accessible form, emphasizing that small populations tend to become inbred as a whole due to the phenomenon of genetic drift. This is a separate phenomenon from mating between relatives, which has long been recognized as inbreeding. Second, we reviewed field studies from both Europe and North America showing that small inbred populations are suffering measurable and often dramatic declines in fitness. Such declines surprised many people, as it notoriously hard to pick up genetic effects in messy field studies. In addition, many did not expect inbreeding effects to be pronounced enough to affect both individual and population fitness appreciably. This work is also of interest to a wide audience because molecular markers (like microsatellites or AFLP's) can be assayed in any population, providing hope that we can survey broad sets of potentially threatened populations to predict which ones are most likely to suffer from genetic problems.

I've been doing work on inbreeding since my Ph.D. research on selfing and outcrossing in jewelweed (Impatiens capensis) in the late 1970s. Starting in the 1980s, my students and I started to work on the demography and genetics of rare and threatened plant species. Eric Menges found that in the Royal Catchfly (Silene regia - the 'cover girl' for the TREE article), small populations suffered a sharp reduction in seed viability. This suggested an inbreeding effect, as they were clearly getting pollinated. More recently, I've been doing experiments to understand the genetic changes that occur in bottlenecked and/or inbred populations. This work uses fast-cycling Brassica rapa plants as "lab rats" to see how multiple generations of inbreeding in a historically outcrossing population affects various fitness components. I'm particularly interested in testing the idea that strong selection in newly inbred populations can "purge" the genetic load.