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Abstract
The lubber grasshopper, Romalea guttata, is an endemic species to the southern United States. Mitochondrial cytochrome b sequences were used to explore population genetic structure and gene flow, intraspecific phylogeography, and the effects of the last ice age on the genetic structure in this low mobile species. Phylogenetic and statistical results indicated that the R. guttata populations did not show ma or geographic grouping based on the geographic distribution of the genetic diversity. When the genetic diversity was partitioned into different hierarchical levels, the largest was within each population. The highest genetic diversity was in the northern Florida populations whereas the lowest was in the Copeland population. The statistical analyses also indicated that most populations of this species have undergone drastic declines in size. Phylogeographic analyses based on mtDNA using PAUP did not reveal any major clade structure in terms of the geographic origin of the haploytpes. The haplotype age estimates obtained from PHYLIP suggested that most haplotypes were about the same age. The most divergent mtDNA haplotype were found in the northern Florida, however, the results did not support the hypothesis that this haplotype was not a refuge haplotype, instead it could indicate retained ancestral polymorphism.
