William Chapco, Greg Litzenberger
Journal of Orthoptera Research 11 (1), 1-9, (1 June 2002) https://doi.org/10.1665/1082-6467(2002)011[0001:AMPAOT]2.0.CO;2
KEYWORDS: Melanoplus, mitochondrial DNA, phylogeny
This research expands upon our previous molecular phylogenetic analysis of the genus Melanoplus by incorporating additional mitochondrial genes, taxa and specimens. Included are two monotypic genera suspected of close affiliation with Melanoplus: Phoetaliotes and Bohemanella. Portions of four mitochondrial genes, coding for cytochrome b, cytochrome oxidase subunits I and II, and NADH dehydrogenase subunit II, were sequenced and phylogenetically analyzed using (weighted and unweighted) parsimony and neighbor-joining methods. Maximum resolution of relationships was achieved using weighted parsimony and by treating all sequences, totaling 1716 base pairs, as a unit.
The following large clades emerged in parsimony analyses, supported by moderate to poor bootstrap values: A — sanguinipes, femurrubrum, devastator, gaspesiensis, fasciatus, borealis, madeleineae, dawsoni; B — packardii, foedus, angustipennis, gladstoni, aspasmus; C — bivittatus, franciscanus, keeleri, calidus, littoralis, differentialis; D — infantilis, alpinus, aridus, Phoetaliotes, scudderi; and E — confusus, Bohemanella, marginatus, microtatus. M. lakinus was basal to all species. Deviations from the conventional literature in which species are organized into species groups or series are discussed. It is concluded that many such groups are phylogenetically questionable; their validity warrants serious reconsideration.
Two phenomena - a rapid burst (or bursts) of speciation occurring early in the genus' evolution and an absence of complete lineage sorting for certain closely related species - are nicely illustrated by Melanoplus. We provide evidence that the massive radiation that took place within the past 4 My, inferred previously by Knowles and Otte, extends to a wider base of taxa, beyond the particular species studied by these authors.