Giving an Invited Biology Seminar at the University of San Francisco
In September, I was invited to give a Biology Department seminar at the University of San Francisco on my postdoctoral research on western monarch butterflies (Danaus plexippus). My talk, “Breaking an eastern paradigm: Breeding ecology of western monarch butterflies,” focused on how monarchs spread back across the western United States to breed each spring and summer, a surprisingly unresolved part of their annual cycle.
This work is part of a long-term collaboration among researchers at UC Davis, Washington State University, and the Xerces Society for Invertebrate Conservation. I lead the UC Davis component of the current project, including curating and integrating survey data from across regions, conducting analyses of the combined dataset, and writing technical reports that synthesize our findings. These repeated surveys allow us to compare breeding phenology, or the seasonal timing of reproduction, across the western breeding range.
Much of what we expect monarchs to do in spring comes from the much better-studied eastern population. In the East, spring recolonization is commonly described using a successive-broods model, in which different generations progressively breed farther north as the season advances. Our western data show a different pattern. Breeding generally begins earlier closer to the California overwintering grounds and expands north and east, but often continues in those earlier regions as breeding begins elsewhere. Rather than a simple generational relay across the landscape, breeding overlaps substantially among regions.
Giving the seminar was an opportunity to step back from the individual surveys and analyses and present the larger ecological question that has emerged from this collaborative work. It was especially useful to discuss the research with a broad biology audience and think about what western monarchs can tell us more generally about how migratory species spread across large landscapes over multiple generations.
