Mating Habits, Dispersal and Postglacial Range Expansion of Nigronia Serricornis (Say) (Megaloptera: Corydalidae)
It was hypothesized that fragmentation and isolation-by-distance would be evident in the genetic population structure, due to poor dispersal ability. Using sequence data from a 630-base fragment of cytochrome oxidase I (COI), nested clade phylogeographical analysis (NCPA) was performed to determine the patterns of genetic diversity and the effects of post-glacial range expansion (PGRE). Haplotype diversity was significantly negatively correlated with latitude (R2 = 0.475, p = 0.002), as seen in other species experiencing PGRE in eastern North America. The 68 unique COI haplotypes recovered were distributed into 6 major clades. A rapid range expansion arose from Tennessee colonizing Indiana, Illinois, Wisconsin, Michigan, and Ontario. Evidence was found for two contiguous range expansions: Pennsylvania into New York and North Carolina along the coast to Maine. Points of secondary contact were identified in New York and Ohio. The remaining clades showed no significant phylogeographic relationship according to the NCPA. The distribution of one of these clades, however, followed pre-glacial drainages. Fragmentation and isolation-by-distance were rampant throughout the range of the species, corroborating the conclusion of poor dispersal ability. Low levels of genetic diversity and poor dispersal make N. serricornis susceptible to anthropogenic population fragmentation.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign