Butterfly blues: population genetic assessment of wild lupine (Lupinus perennis L.) in endangered Karner blue butterfly habitat around central-west Michigan

Habitat degradation can have significant effects on native species inhabiting natural ecosystems. Within oak barrens and oak-pine barrens ecosystems, there is a complex interspecies interaction between the federally endangered Karner blue butterfly (Lycaeides melissa samuelis) and its obligate host plant, wild lupine (Lupinus perennis L.). Recruitment of wild lupine is critical for maintaining butterfly populations; however, this recruitment can be impeded by habitat fragmentation. Reduced recruitment can result in low genetic diversity in isolated populations, limiting its adaptive potential to respond to environmental change. This study was aimed at understanding the genetic diversity and population structure of wild lupine populations throughout central and west Michigan. We identified significant population structure across most of the populations sampled, with only two sites not significantly different from each other. No sites within our study area displayed statistically significant levels of inbreeding. There are also at least two genetic clusters of wild lupine present within our study region, although there is significant overlap among these groups, indicating that genetic differentiation among clusters may be limited.