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D A Mcfadyen - One of the best experts on this subject based on the ideXlab platform.

  • Mitochondrial DNA variation in North American melanopline grasshoppers
    Heredity, 1994
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Restriction fragment analysis of mitochondrial DNA (mtDNA) was used to examine genetic variation within and among 11 species of grasshoppers in the subfamily Melanoplinae. Total DNA of 236 individuals was digested with 10 restriction enzymes and probed with three cloned Eco RI fragments representing the entire mitochondrial genome of Melanoplus sanguinipes . The average size of mtDNA for these species was about 16.1 kilobases. Average nucleotide diversities within species ranged from 0.00 to 0.31 per cent. Values are considered low and possibly reflect chronically small population sizes in pre-agricultural times as well as bottlenecks engendered by various glacial episodes. Species regarded as major pests appear to have larger diversities. For each species, common genotypes occur throughout the sampled region suggesting very little spatial differentiation although in a couple of melanoplines, one or two haplotypes are geographically restricted. Comparisons among species led to a hypothesis concerning their phylogenetic relationships. Not all affinities accorded with expectations based on morphological comparisons. The estimated time of divergence for the genus Melanoplus is at least 4 million years.

  • Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes
    Heredity, 1992
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes

W. Chapco - One of the best experts on this subject based on the ideXlab platform.

  • a molecular phylogenetic analysis of the grasshopper genus Melanoplus stal orthoptera acrididae an update
    Journal of Orthoptera Research, 2002
    Co-Authors: W. Chapco, Greg Litzenberger
    Abstract:

    Abstract 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;...

  • A molecular phylogenetic analysis of the grasshopper genus Melanoplus Stål (Orthoptera: Acrididae) – an update
    Journal of Orthoptera Research, 2002
    Co-Authors: W. Chapco, Greg Litzenberger
    Abstract:

    Abstract 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;...

  • Molecular Phylogeny of Melanopline Grasshoppers (Orthoptera: Acrididae): the Genus Melanoplus
    Annals of the Entomological Society of America, 1999
    Co-Authors: W. Chapco, W. R. Kuperus, G. Litzenberger
    Abstract:

    A molecular phylogenetic analysis of several species of Melanoplus was undertaken to clarify the taxonomic relationships among members of this very large North American grasshopper genus. The study tested the validity of several long-standing morphologically based “species-groups.” To achieve these goals, portions of 3 mitochondrial genes (cytb, COII, and 16S ribosomal RNA) were sequenced and phylogenetically analyzed using (weighted and unweighted) parsimony and neighbor-joining methods. Agreement with many of the groupings suggested by the early orthopterists was mixed, as illustrated by the following assemblages, emerging with varying levels of bootstrap support: (1) ([([ sanguinipes, femurrubrum ], devastator ), bruneri ], dawsoni ); (2) ([ packardii, foedus ], angustipennis ); (3) ( bivittatus, differentialis ); (4) ( infantilis, alpinus ); (5) ( kennicotti, bowditchi ); and (6) ( confusus, occidentalis ). Some support for the claim that the group Marginatus constituted the most “primitive” species-group was provided by the basal position occupied by its nominate species. A suggestion by Vickery that diversity within Melanoplus is sufficiently large to warrant division is discussed.

  • Mitochondrial DNA variation in North American melanopline grasshoppers
    Heredity, 1994
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Restriction fragment analysis of mitochondrial DNA (mtDNA) was used to examine genetic variation within and among 11 species of grasshoppers in the subfamily Melanoplinae. Total DNA of 236 individuals was digested with 10 restriction enzymes and probed with three cloned Eco RI fragments representing the entire mitochondrial genome of Melanoplus sanguinipes . The average size of mtDNA for these species was about 16.1 kilobases. Average nucleotide diversities within species ranged from 0.00 to 0.31 per cent. Values are considered low and possibly reflect chronically small population sizes in pre-agricultural times as well as bottlenecks engendered by various glacial episodes. Species regarded as major pests appear to have larger diversities. For each species, common genotypes occur throughout the sampled region suggesting very little spatial differentiation although in a couple of melanoplines, one or two haplotypes are geographically restricted. Comparisons among species led to a hypothesis concerning their phylogenetic relationships. Not all affinities accorded with expectations based on morphological comparisons. The estimated time of divergence for the genus Melanoplus is at least 4 million years.

  • Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes
    Heredity, 1992
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes

R A Kelln - One of the best experts on this subject based on the ideXlab platform.

  • Mitochondrial DNA variation in North American melanopline grasshoppers
    Heredity, 1994
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Restriction fragment analysis of mitochondrial DNA (mtDNA) was used to examine genetic variation within and among 11 species of grasshoppers in the subfamily Melanoplinae. Total DNA of 236 individuals was digested with 10 restriction enzymes and probed with three cloned Eco RI fragments representing the entire mitochondrial genome of Melanoplus sanguinipes . The average size of mtDNA for these species was about 16.1 kilobases. Average nucleotide diversities within species ranged from 0.00 to 0.31 per cent. Values are considered low and possibly reflect chronically small population sizes in pre-agricultural times as well as bottlenecks engendered by various glacial episodes. Species regarded as major pests appear to have larger diversities. For each species, common genotypes occur throughout the sampled region suggesting very little spatial differentiation although in a couple of melanoplines, one or two haplotypes are geographically restricted. Comparisons among species led to a hypothesis concerning their phylogenetic relationships. Not all affinities accorded with expectations based on morphological comparisons. The estimated time of divergence for the genus Melanoplus is at least 4 million years.

  • Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes
    Heredity, 1992
    Co-Authors: W. Chapco, R A Kelln, D A Mcfadyen
    Abstract:

    Intraspecific mitochondrial DNA variation in the migratory grasshopper, Melanoplus sanguinipes

Horta-vega Jorge - One of the best experts on this subject based on the ideXlab platform.

L. Lacey Knowles - One of the best experts on this subject based on the ideXlab platform.

  • Variable nuclear markers for Melanoplus oregonensis identified from the screening of a genomic library
    Molecular Ecology Notes, 2006
    Co-Authors: Bryan C. Carstens, L. Lacey Knowles
    Abstract:

    We report the isolation of seven single-copy nuclear loci from the montane grasshopper Melanoplus oregonensis. With an average length of approximately 930 bp and between five and 67 variable sites, these loci are useful for population genetic analyses within M. oregonensis. Amplification of nuclear loci in additional species of western Melanoplus grasshoppers suggests that they will also be useful for a variety of population genetic, phylogeographic and phylogenetic studies.

  • Genealogical portraits of speciation in montane grasshoppers (genus Melanoplus) from the sky islands of the Rocky Mountains.
    Proceedings. Biological sciences, 2001
    Co-Authors: L. Lacey Knowles
    Abstract:

    Grasshoppers in the genus Melanoplus have undergone a radiation in the 'sky islands' of western North America, with many species originating during the Pleistocene. Despite their recent origins, phylogenetic analyses indicate that all the species exhibit monophyletic or paraphyletic gene trees. The objectives of this study were to determine whether the monophyletic genealogies are the result of a bottleneck at speciation and to investigate the extent to which the different phylogenetic states of eight species (i.e. monophyletic versus paraphyletic gene trees) can be ascribed to the effects of speciation. A coalescent simulation was used to test for a bottleneck at speciation in each species. The effective population sizes and demographic histories of species were compared across taxa to evaluate the possibility that the paraphyly versus monophyly of the species reflects differential rates of lineage loss rather than speciation mode. While coalescent analyses indicate that the monophyly of Melanoplus species might not be indicative of bottlenecks at speciation, the results suggest that the paraphyletic gene trees may reflect the demography of speciation, involving localized divergences in the ancestral species. With respect to different models of Pleistocene divergence, the data do not support a model of founder-effect speciation but are compatible with divergence in allopatric refugia.

  • Phylogenetic Analysis of Montane Grasshoppers from Western North America (Genus Melanoplus, Acrididae: Melanoplinae)
    Annals of the Entomological Society of America, 2000
    Co-Authors: L. Lacey Knowles, D. Otte
    Abstract:

    The phylogenetic relationships and divergence times of 25 species of melanopline grasshoppers from western North America were estimated using mitochondrial DNA sequence data from a 1300-bp fragment of cytochrome oxidase I. Although only a few of the >350 species of Melanoplus were studied, the monophyly of the genus and observed sequence divergence suggests the group has radiated within the last 3.5 million years. Much of Melanoplus diversity is concentrated in the montane species groups endemic to the various mountain systems in western North America. Although species divergences correspond to different geologic events, the recency of species origins indicates that older geotectonic events such as mountain uplift were not involved. Sequence divergences indicate that many of the species originated during the Pleistocene, but others apparently originated during the late Pliocene. Although it appears that the diversity of Melanoplus has been generated by both large scale and localized dispersal-vicariance events (i.e., regional and interisland divergences, respectively), such inferences must be made cautiously because the rate of speciation has been high and some of the phylogenetic estimates are consequently uncertain. The short internodes separating some of the species not only restrict phylogenetic resolution, but also increase the probability that the gene genealogy may not accurately reflect species relationships because of lineage sorting. Despite these limitations, the findings of this study indicate that Melanoplus has undergone a recent radiation with rates of speciation comparable to other radiations such as the African cichlids and the drosophilids of the Hawaiian islands.