Doctor of Philosophy
Dr. Nusha Keyghobadi
Habitat fragmentation and loss are leading threats to global biodiversity and can alter patterns of dispersal, population dynamics, and genetics with implications for long-term species persistence. Most habitat fragmentation research has focused on recently fragmented species that historically occupied interconnected habitat patches. We know comparatively little about how naturally fragmented species may respond to habitat loss. For these species, local habitat patch quality may influence the dynamics and genetics of populations more than the structure of the surrounding landscape (e.g., degree of isolation of suitable habitat). I examined aspects of the ecology and evolution of populations inhabiting fragmented landscapes, using two butterfly species representing relict populations that are 1) recently fragmented by anthropogenic activities (Mormon metalmark, Apodemia mormo), and 2) naturally fragmented (bog copper, Lycaena epixanthe). I assessed patterns of genetic (amplified fragment length polymorphism, AFLP) and flight-related morphological variation, and their relationship to measures of surrounding landscape structure and local habitat quality.
Population genetic analysis of the anthropogenically fragmented Mormon metalmark revealed a high degree of spatial genetic structure, indicating limited gene flow, despite a small geographic scale (<20 >km). Management of this endangered population should focus on increasing connectivity among the most isolated sub-populations and through urban areas. For the naturally fragmented bog copper, genetic diversity was explained by variables related to patch quality rather than landscape structure. Movement ability in the bog copper (inferred by flight morphology) appeared to depend on both local habitat conditions and the surrounding landscape. Also, using an AFLP-based genome scan approach, I identified signatures of selection in the bog copper associated with fine-scale landscape heterogeneity. My work on the bog copper highlights the importance of considering the effects of local habitat conditions, in addition to habitat isolation, for conservation of fragmented populations.
Finally, I also reviewed the current literature (470 articles) to evaluate the quality of AFLP data used in ecological and evolutionary research. I discovered a pervasive lack of consistency and transparency in both the methods used to assess data reproducibility, and in the details of methodology presented. This work has identified an important publishing gap in molecular ecology research.
Crawford, Lindsay A., "Genetic and morphological variation of butterflies in relict habitats" (2013). Electronic Thesis and Dissertation Repository. 1600.