Mitochondrial DNA Variation in the South American Grasshopper <I>Dichroplus elongatus</I> (Orthoptera: Acrididae)

Abstract

Dichroplus elongatus (Giglio-Tos) is a phytophagous grasshopper widely distributed in Argentina. In the current work, the genetic variation and phylogeography of this species was studied with mtDNA techniques. In total, 171 individuals from northwestern (Las Yungas province) and eastern (Espinal and Pampeana provinces) Argentina populations were analyzed using restriction fragment-length polymorphism. The number of substitutions per site between pairs of haplotypes ranged from 0.65 to 3.84%. The neighbor-joining phenogram yielded two main groups; one clusters together the haplotypes restricted to the east and the other the haplotypes restricted to the northwestern region. Phylogenetic consensus unrooted tree among mtDNA haplotypes allowed us to propose the ancestral haplotype, which occupies the central position of the network. The unweighted pair-group method with arithmetic average dendrogram from nucleotide divergence among populations showed that populations are roughly grouped according to their geographic distribution. There was a significant heterogeneity of the mtDNA distribution when populations from all three biogeographic provinces were compared. The distribution patterns of mtDNA variation observed in D. elongatus may be explained by isolation by distance when referring to the main biogeographic provinces. In Las Yungas and Pampeana provinces, ecological factors seem to have contributed to the genetic differentiation among populations.