Master of Science
In the current age of widespread anthropogenic effects across the globe, organisms are vulnerable to habitat fragmentation and localized decline in population more than ever before. Therefore, insight into metapopulation-level dynamics and the genetic basis of inter-patch dispersal is key to understanding the regional persistence of a species in the face of potential localized extinction or population bottleneck. In this study I used samples from a previously conducted localized long-term population removal experiment to investigate the effects of an extended population reductions on the genetic structure of a local population, and to explore the genetic basis of dispersal and recolonization using both the removal experiment and past natural local extinctions within a well-studied metapopulation system of an alpine butterfly species (Parnassius smintheus). Overall, while my results did not find evidence for the genetic basis of dispersal in this species within the markers assayed, genetic metrics across the experiment empirically demonstrated this system’s resilience against localized population reductions, as both genetic diversity and influx of dispersers into the focal patches were maintained throughout the experiment despite the yearly removals of the local populations for eight consecutive years.
Summary for Lay Audience
In the current age of widespread human land-use change across the globe, more and more organisms are left existing in a fragmented landscape, where they are vulnerable to localized decline or even extinctions more than ever before. In these fragmented landscapes, dispersal of individuals among habitat patches play an important role in the recovery and persistence of local populations, especially in the face of dramatic population reductions. Additionally, dispersal is a trait that can be affected by the genetics of an individual, and therefore, disturbances that cause local population reductions can lead to the increased representation of dispersers within a patch, when the patch becomes recolonized by individuals from other habitat patches. In my project, I investigated the genetic characteristics of an alpine butterfly species, the Rocky Mountain apollo (Parnassius smintheus) within a regional population network located in the Canadian Rockies. On top of natural local extinctions that have occurred in the past, in two of the patches, all observed butterflies were annually captured and artificially removed from year 2001 to 2008 as part of a population dynamics experiment. I tracked the impact of this long-term removal on the genetic characteristics of these patches throughout the experiment, assessed the origin of the dispersers coming into them, and explored a genetic basis of dispersal and recolonization in this system using recolonization events caused by both the experimental removal and natural extinctions. Genetic metrics across the experiment demonstrated this system’s resilience against local population reductions even over a prolonged period, as both available genetic diversity and influx of dispersers into the decimated patches were maintained throughout the experiment, despite the continuous removal over eight years.
Park, Keon Young, "The impact of long-term artificial removal experiment and natural local extinctions on the genetics of an alpine butterfly" (2022). Electronic Thesis and Dissertation Repository. 8611.