The history and geography of diversification within the butterfly genus Lycaeides in North America

Abstract

The Lycaeides butterfly species complex in North America consists of two nominal, morphologically defined species. These butterflies are ecologically diverse and appear to be distributed as a geographically complex mosaic of locally differentiated populations that may be undergoing adaptive radiation. We asked whether patterns of molecular genetic variation within the species complex are congruent with currently recognized morphological species and whether the distribution of molecular variation is consistent with the hypothesis that Pleistocene climate changes contributed to the process of differentiation within the genus. Variation in the form of the genitalia from 726 males from 59 populations clearly distinguishes both species with only six populations containing morphologically intermediate or ambiguous individuals. However, partitioning of molecular variance in a 236 bp section of the mitochondrial AT-rich region from 628 individuals (57 populations) surveyed using single strand conformation polymorphism analysis (SSCP) indicates that only 26% of the total genetic variation is distributed along nominal species boundaries as defined by morphology. Instead, three phylogeographical groups were detected, represented by three major haplotype clades, which account for 90% of the total genetic variance. Pleistocene glaciations appear to have fostered divergence during glacial maxima, while post-glacial range expansions created opportunities for gene exchange and reticulation along suture zones between geographical groups. Data presented here allow us to make inferences about the history of the species complex. However, evidence of ancestral polymorphism and reticulation limit our ability to define species boundaries based on mitochondrial DNA sequence variation.

Hybridization between two gartersnake species (Thamnophis) of conservation concern: a threat or an important natural interaction?

“…Results from mtDNA and AFLP supported the general conclusion that T. butleri populations that occur east of Lake Michigan are significantly different from populations that occur west of Lake Michigan, lending further support to previous studies on recolonization of the Great Lakes region following the last glaciation (Austin et al 2002;Zamudio and Savage 2003;Nice et al 2005;Placyk et al 2007). In contrast, T. radix showed no geographic structure.…”

Recovery of DNA from archaeological insect remains: first results, problems and potential

“…Schrey et al, 2005;Smith and Farrell, 2005), human lice (Leo et al, 2002;Yong et al, 2003), and butterflies (e.g. Nice et al, 2005). All of these studies of modern genomes have been relevant to palaeoecological questions, but all lack an essential element: information about the genetic constitution of ancient populations.…”

Population genetic structure of three tree species in the mangrove genus Ceriops (Rhizophoraceae) from the Indo West Pacific

“…Gene diversity statistics were further calculated for the three geographical regional groups identified by the cluster analysis, i.e., EIO, SCS, and the coast of NA. For phenetic analyses, analysis of molecular variance (AMOVA) was performed using AMOVA Version 1.55 (Excoffier 1993) to determine whether genetic variation was distributed according to current boundaries within Ceriops, or, alternatively, whether genetic variance is partitioned geographically as might be the case if Nice et al 2005). A second AMOVA were arranged to calculate the genetic variation distribution among regions, among populations within a region, and within populations.…”