The phylogenetic relationships among selected species and genera of Gerrinae (Heteroptera: Gerrid... more The phylogenetic relationships among selected species and genera of Gerrinae (Heteroptera: Gerridae) were investigated in a parsimony analysis of 2268 bp of DNA sequence data from the genes encoding COI + II, 16S rRNA and 28S rRNA. The taxa represented 12 of 15 recognized genera of Gerrinae and with outgroup taxa from all other subfamilies of Gerridae, including three of five recognized genera of Eotrechinae, which is considered the sister-group of Gerrinae. The resulting phylogeny shows that Gerrinae is not monophyletic, since a clade comprising Gerris, Aquarius, Limnoporus, Tachygerris, Eurygerris and Gigantometra is more closely related to representatives of the subfamily Eotrechinae than to a clade comprising Limnogonus, Neogerris, Limnometra, Tenagogerris and Tenagogonus. The two currently recognized gerrine tribes, Tachygerrini and Gerrini, were also paraphyletic, since Eurygerris was sister-group to Gigantometra, while Tachygerris was sister-group to Limnoporus + Aquarius + Gerris. Limnogonus and Neogerris were found to be strongly supported sister-taxa, and their sister-group was a clade comprising Limnometra, Tenagogerris and Tenagogonus, none of which were monophyletic. Finally, Aquarius chilensis (Berg, 1881) was sister-group to a clade comprising Aquarius amplus (Drake & Harris, 1938), A. remigis (Say, 1832) and A. remigoides (Gallant & Fairbairn, 1993), recognized as the A. remigis species group, and the entire clade was sister-group to Gerris. Based on the phylogenetic reconstruction, we outline possible diagnostic character combinations for a future revision of the Gerrinae and discuss the fossil record. While some of the relationships reinstate earlier ideas, e.g., Limnogonus and Neogerris being sister groups, many others are poorly supported and poorly diagnosed, and therefore, we retain from drawing taxonomic conclusions until data is available from the remaining genera, which can support a future generic revision of the Gerrinae. The updated checklist of species assigned to the subfamily is therefore based on the established taxonomy.
Distribution, phenology and status is given for the five Danish species of larger Branchiopoda. A... more Distribution, phenology and status is given for the five Danish species of larger Branchiopoda. All species are univoltine and inhabit small, temporary waterbodies. The distribution of all species is very restricted in Denmark, probably because of habitat destruction.
Carbon, nitrogen or phosphorus limitation of microbial growth in a forest and a field soil was ev... more Carbon, nitrogen or phosphorus limitation of microbial growth in a forest and a field soil was evaluated from measurements of respiration and protozoan counts after nutrient addition. In both soils simultaneous addition of C (glucose) and N (NH,NO,) resulted in microbial growth as indicated by a gradual increase in respiration rate whereas a single addition of C did not induce microbial growth. Addition of P (KH?PO, + Na2HP04) to C-amended soil stimulated activity slightly in forest soil but not in field soil whereas addition of P to soil amended with C and N increased growth markedly in both soils. The stimulation of microbial growth indicated by respiration profiles following C and N addition was supported by enumeration of bacterivorous protozoa. The numbers of soil protozoa increased above the control only when C and N were added simultaneously. These observations lend support to the proposal that respiration patterns may be valuable in an analysis of nutrient limitation of microbial growth in soils.
We examined phylogenetic relationships among halobatine water striders (Hemiptera, Gerridae) usin... more We examined phylogenetic relationships among halobatine water striders (Hemiptera, Gerridae) using molecular and morphological data. The molecular data set was 780 bp DNA sequence data from the 3′ half of the mitochondrial gene encoding cytochrome oxidase subunit I from 19 species of sea skaters, Halobates, and one species from each of three related genera, Asclepios annandalei, Austrobates rivularis, and Eurymetra natalensis. The morphological data set was a slightly modified version of a previously published data set. Unweighted parsimony analyses of the molecular data set gave one tree with weak support for most branches. Maximum likelihood analysis of the same data set gave a tree with slightly different topology, but reveiled many of the clades found in parsimony analyses of the morphological data set. Parsimony analyses of the combined molecular + morphology data sets gave a better
Morphological characters and molecular sequence data were for the first time analysed separately ... more Morphological characters and molecular sequence data were for the first time analysed separately and combined for the true water bugs (Hemiptera-Heteroptera, infraorder Nepomorpha). Data from forty species representing all families were included, together with two outgroup species representing the infraorders Gerromorpha and Leptopodomorpha. The morphological data matrix consisted of sixty-five characters obtained from literature sources. Molecular data included approximately 960 bp from the mitochondrial gene 16S and the nuclear gene 28S for all forty-two terminal taxa. The morphological dataset was analysed using maximum parsimony and the combined morphological and molecular (16S þ 28S rDNA) dataset was analysed using direct optimization. A sensitivity analysis of sixteen different sets of parameters (various combinations of insertion-deletion cost and transversion costs) was undertaken.
We investigated phylogenetic relationships of water striders (Hemiptera-Heteroptera: Gerridae) fr... more We investigated phylogenetic relationships of water striders (Hemiptera-Heteroptera: Gerridae) from the three principal Holarctic genera, Aquarius Schellenberg, Limnoporus Sta˚l and Gerris Fabricius with parsimony analyses of sixty-six morphological characters and DNA sequences from mitochondrial (cytochrome c oxidase subunit I þ II; large mitochondrial ribosomal subunit) and nuclear (elongation factor 1-alpha) genes. The taxon sampling included all species of Aquarius and Limnoporus, and a dense, near complete, sample of Gerris species with representatives from all subgenera and species groups, and Gigantometra gigas (China) was selected as an outgroup species. A simultaneous analysis of all data sets gave eight equally parsimonious trees, and a strict consensus tree left only a few relationships within Gerris unresolved. While Limnoporus and Gerris each were resolved as monophyletic entities, Aquarius was found to be polyphyletic, because the Nearctic Aquarius remigis-group, comprising A. remigis (Say), A. amplus (Drake and Harris), A. nyctalis (Drake and Hottes) and A. remigoides Gallant and Fairbairn, was placed as sister group to Gerris, while the Andean Aquarius chilensis (Berg) was sister group to all three genera. Remaining species of Aquarius comprised a sister group to the Gerris þ the A. remigis-group clade. Based on our phylogenetic reconstruction we discuss relationships within and among the three genera, reassess and diagnose species groups, and discuss zoogeographical relationships among all taxa.
Phylogenetic relationships between water striders (Heteroptera: Gerridae) of genus Gerris Fabrici... more Phylogenetic relationships between water striders (Heteroptera: Gerridae) of genus Gerris Fabricius were examined using molecular and morphological characters. The molecular dataset was 820 bp DNA from the 3¢ half of the mitochondrial gene encoding cytochrome oxidase subunit I and 515 bp DNA from the nuclear gene encoding elongation factor 1 alpha. The morphological dataset was a slightly modi®ed version of a previously published dataset. Representatives from all eight recognized species groups of Gerris, as well as six species from three related genera, including Gigantometra gigas, Limnoporus esakii, L. rufoscutellatus, Aquarius najas, A. conformis and A. paludum, were included. Unweighted parsimony analyses of the COI sequences gave a topology with strong support for only those nodes that were already recognized as closely related based on morphological characters. Similar analyses of EF-1a gave a cladogram with a topology quite different from that based on morphology and COI. Unweighted parsimony analyses of the`total evidence' dataset largely supports the traditional view of Gerris phylogeny. Finally, the implications of the reconstructed phylogeny in relation to biogeography and ecological phylogenetics of Gerris is discussed. # 2001 Blackwell Science Ltd 241 Systematic Entomology (2001) 26, 241±254 Systematic Entomology (2001) 26, 241±254 X Fig. 2. Number of inferred steps based on Fig. 1 against uncorrected (p) distances for pairwise comparisons between 820 bp nucleotide sequences of COI in PAUP*.
We examined the phylogeny of Mantophasmatodea from southern Africa (South Africa, Namibia) using ... more We examined the phylogeny of Mantophasmatodea from southern Africa (South Africa, Namibia) using approx. 1300 bp of mitochondrial DNA sequence data from the genes encoding COI and 16S. The taxon sample comprised multiple specimens from eight described species (Namaquaphasma ookiepense, Austrophasma rawsonvillense, A. caledonense, A. gansbaaiense, Lobatophasma redelinghuysense, Hemilobophasma montaguense, Karoophasma botterkloofense, K. biedouwense) and four undescribed species of Austrophasmatidae; three specimens of Sclerophasma paresisense (Mantophasmatidae); and two specimens of Praedatophasma maraisi and one of Tyrannophasma gladiator (not yet convincingly assigned to any family). For outgroup comparison a broad selection from hemimetabolous insect orders was included. Equally weighted parsimony analyses of the combined COI + 16S data sets with gaps in 16S scored as a fifth character state supported Austrophasmatidae and all species and genera of Mantophasmatodea as being monophyletic. Most species were highly supported with 98-100% bootstrap/7-39 Bremer support (BS), but K. biedouwense had moderate support (87/4) and A. caledonense low support (70/1). Mantophasmatodea, Austrophasmatidae, and a clade Tyrannophasma gladiator + Praedatophasma maraisi were all strongly supported (99-100/12-25), while relationships among the two latter clades and Mantophasmatidae remain ambiguous. Concerning the relationships among genera of Austrophasmatidae, support values are moderately high for some nodes, but not significant for others. We additionally calculated the partitioned BS values of COI and 16S for all nodes in the strict consensus of the combined tree. COI and 16S are highly congruent at the species level as well as at the base of Mantophasmatodea, but congruence is poor for most intergeneric relationships. In forthcoming studies, deeper relationships in the order should be additionally explored by nuclear genes, such as 18S and 28S, for a reduced sample of specimens.
Page 1. Phylogeny of the water strider genus Aquarius Schellenberg ... We examined phylogenetic r... more Page 1. Phylogeny of the water strider genus Aquarius Schellenberg ... We examined phylogenetic relationships among gerrid water striders of the genus Aquarius Schellenberg using molecular and morphological characters. ...
Pumas occupy the largest latitudinal range of any New World terrestrial mammal. Human population ... more Pumas occupy the largest latitudinal range of any New World terrestrial mammal. Human population growth and associated habitat reduction has reduced their North American range by nearly two-thirds, but the impact of human expansion in Central and South America on puma populations is not clear. We examined mitochondrial DNA diversity of pumas across the majority of their range, with a focus on Central and South America. Four mitochondrial gene regions (1140 base pairs) revealed 16 unique haplotypes differentiating pumas into three
Incongruence among trees reconstructed with different data may stem from historical (gene tree-sp... more Incongruence among trees reconstructed with different data may stem from historical (gene tree-species tree conflict) or process (character change biases) phenomena. Regardless of the source, incongruent data, as determined with ''global'' measures of homoplasy, have often been excluded from parsimony analysis of the combined data. Recent studies suggest that these homoplasy measures do not predict the contribution of each character to overall tree structure. Branch support measures identify, on a character to node basis, sources of support and conflict resulting from a simultaneous analysis of the data. We implement these branch support measures to identify sources of character conflict in a clade of water striders consisting of Gerris Fabricius, Aquarius Schellenberg, and Limnoporus St a al species. Separate analyses of morphology, mitochondrial cytochrome oxidase I (COI), large mitochondrial ribosomal subunit (16SrRNA), and elongation factor-1a (EF-1a) data resulted in cladograms that varied in resolution and topological concordance. Simultaneous analysis of the data resulted in two trees that were unresolved for one node in a strict consensus. The topology agreed with current classification except for the placements of Aquarius chilensis and the Aquarius remigis species group closer to Gerris than to congeneric species. Branch support measures indicated that support derived from each data set varied among nodes, but COI had an overall negative effect on branch support. However, Spearman rank correlation of partitioned branch support values indicated no negative associations of branch support between any data sets and a positive association between EF-1a and 16SrRNA. Thus incongruence among data sets was not drastic and the gene-tree versus species tree phenomenon was not implicated. Biases in character change were a more likely reason for incongruence, although saturation curves and incongruence length difference for COI indicated little potential for homoplasy. However, a posteriori inspection of COI nucleotide change with reference to the simultaneous analysis tree revealed AT and codon biases. These biases were not associated with branch support measures. Therefore, it is difficult to predict incongruence or identify its cause. Exclusion of data is ill advised because every character is potentially parsimony informative.
We investigated phylogenetic relationships among pond skaters (Heteroptera: Gerridae) of the genu... more We investigated phylogenetic relationships among pond skaters (Heteroptera: Gerridae) of the genus Limnogonus Stål 1868 by performing separate and combined parsimony analyses of DNA sequences from three mitochondrial (COI + II, 16SrRNA) and one nuclear (28SrRNA) gene(s). The taxon sample represented almost two thirds of the known diversity, and with most taxa represented by two or more individuals. A simultaneous analysis of all data showed that L. luctuosus Montrousier 1865 was paraphyletic and suggests that ''L. luctuosus" from Australia and possibly also a population from the Society Islands (Moorea) each represents unrecognized species. L. fossarum F. 1775 was strongly supported, but the two subspecies L. f. fossarum F. 1775 and L. f. gilguy Andersen and Weir 1997 were paraphyletic. The two currently recognized subgenera Limnogonus (s. str.) Stål 1868 and L. (Limnogonoides) Andersen 1975 were paraphyletic, and were accordingly broken up in several monophyletic groups, each containing one or more species. From Limnogonus
The phylogenetic relationships among selected species and genera of Gerrinae (Heteroptera: Gerrid... more The phylogenetic relationships among selected species and genera of Gerrinae (Heteroptera: Gerridae) were investigated in a parsimony analysis of 2268 bp of DNA sequence data from the genes encoding COI + II, 16S rRNA and 28S rRNA. The taxa represented 12 of 15 recognized genera of Gerrinae and with outgroup taxa from all other subfamilies of Gerridae, including three of five recognized genera of Eotrechinae, which is considered the sister-group of Gerrinae. The resulting phylogeny shows that Gerrinae is not monophyletic, since a clade comprising Gerris, Aquarius, Limnoporus, Tachygerris, Eurygerris and Gigantometra is more closely related to representatives of the subfamily Eotrechinae than to a clade comprising Limnogonus, Neogerris, Limnometra, Tenagogerris and Tenagogonus. The two currently recognized gerrine tribes, Tachygerrini and Gerrini, were also paraphyletic, since Eurygerris was sister-group to Gigantometra, while Tachygerris was sister-group to Limnoporus + Aquarius + Gerris. Limnogonus and Neogerris were found to be strongly supported sister-taxa, and their sister-group was a clade comprising Limnometra, Tenagogerris and Tenagogonus, none of which were monophyletic. Finally, Aquarius chilensis (Berg, 1881) was sister-group to a clade comprising Aquarius amplus (Drake & Harris, 1938), A. remigis (Say, 1832) and A. remigoides (Gallant & Fairbairn, 1993), recognized as the A. remigis species group, and the entire clade was sister-group to Gerris. Based on the phylogenetic reconstruction, we outline possible diagnostic character combinations for a future revision of the Gerrinae and discuss the fossil record. While some of the relationships reinstate earlier ideas, e.g., Limnogonus and Neogerris being sister groups, many others are poorly supported and poorly diagnosed, and therefore, we retain from drawing taxonomic conclusions until data is available from the remaining genera, which can support a future generic revision of the Gerrinae. The updated checklist of species assigned to the subfamily is therefore based on the established taxonomy.
Distribution, phenology and status is given for the five Danish species of larger Branchiopoda. A... more Distribution, phenology and status is given for the five Danish species of larger Branchiopoda. All species are univoltine and inhabit small, temporary waterbodies. The distribution of all species is very restricted in Denmark, probably because of habitat destruction.
Carbon, nitrogen or phosphorus limitation of microbial growth in a forest and a field soil was ev... more Carbon, nitrogen or phosphorus limitation of microbial growth in a forest and a field soil was evaluated from measurements of respiration and protozoan counts after nutrient addition. In both soils simultaneous addition of C (glucose) and N (NH,NO,) resulted in microbial growth as indicated by a gradual increase in respiration rate whereas a single addition of C did not induce microbial growth. Addition of P (KH?PO, + Na2HP04) to C-amended soil stimulated activity slightly in forest soil but not in field soil whereas addition of P to soil amended with C and N increased growth markedly in both soils. The stimulation of microbial growth indicated by respiration profiles following C and N addition was supported by enumeration of bacterivorous protozoa. The numbers of soil protozoa increased above the control only when C and N were added simultaneously. These observations lend support to the proposal that respiration patterns may be valuable in an analysis of nutrient limitation of microbial growth in soils.
We examined phylogenetic relationships among halobatine water striders (Hemiptera, Gerridae) usin... more We examined phylogenetic relationships among halobatine water striders (Hemiptera, Gerridae) using molecular and morphological data. The molecular data set was 780 bp DNA sequence data from the 3′ half of the mitochondrial gene encoding cytochrome oxidase subunit I from 19 species of sea skaters, Halobates, and one species from each of three related genera, Asclepios annandalei, Austrobates rivularis, and Eurymetra natalensis. The morphological data set was a slightly modified version of a previously published data set. Unweighted parsimony analyses of the molecular data set gave one tree with weak support for most branches. Maximum likelihood analysis of the same data set gave a tree with slightly different topology, but reveiled many of the clades found in parsimony analyses of the morphological data set. Parsimony analyses of the combined molecular + morphology data sets gave a better
Morphological characters and molecular sequence data were for the first time analysed separately ... more Morphological characters and molecular sequence data were for the first time analysed separately and combined for the true water bugs (Hemiptera-Heteroptera, infraorder Nepomorpha). Data from forty species representing all families were included, together with two outgroup species representing the infraorders Gerromorpha and Leptopodomorpha. The morphological data matrix consisted of sixty-five characters obtained from literature sources. Molecular data included approximately 960 bp from the mitochondrial gene 16S and the nuclear gene 28S for all forty-two terminal taxa. The morphological dataset was analysed using maximum parsimony and the combined morphological and molecular (16S þ 28S rDNA) dataset was analysed using direct optimization. A sensitivity analysis of sixteen different sets of parameters (various combinations of insertion-deletion cost and transversion costs) was undertaken.
We investigated phylogenetic relationships of water striders (Hemiptera-Heteroptera: Gerridae) fr... more We investigated phylogenetic relationships of water striders (Hemiptera-Heteroptera: Gerridae) from the three principal Holarctic genera, Aquarius Schellenberg, Limnoporus Sta˚l and Gerris Fabricius with parsimony analyses of sixty-six morphological characters and DNA sequences from mitochondrial (cytochrome c oxidase subunit I þ II; large mitochondrial ribosomal subunit) and nuclear (elongation factor 1-alpha) genes. The taxon sampling included all species of Aquarius and Limnoporus, and a dense, near complete, sample of Gerris species with representatives from all subgenera and species groups, and Gigantometra gigas (China) was selected as an outgroup species. A simultaneous analysis of all data sets gave eight equally parsimonious trees, and a strict consensus tree left only a few relationships within Gerris unresolved. While Limnoporus and Gerris each were resolved as monophyletic entities, Aquarius was found to be polyphyletic, because the Nearctic Aquarius remigis-group, comprising A. remigis (Say), A. amplus (Drake and Harris), A. nyctalis (Drake and Hottes) and A. remigoides Gallant and Fairbairn, was placed as sister group to Gerris, while the Andean Aquarius chilensis (Berg) was sister group to all three genera. Remaining species of Aquarius comprised a sister group to the Gerris þ the A. remigis-group clade. Based on our phylogenetic reconstruction we discuss relationships within and among the three genera, reassess and diagnose species groups, and discuss zoogeographical relationships among all taxa.
Phylogenetic relationships between water striders (Heteroptera: Gerridae) of genus Gerris Fabrici... more Phylogenetic relationships between water striders (Heteroptera: Gerridae) of genus Gerris Fabricius were examined using molecular and morphological characters. The molecular dataset was 820 bp DNA from the 3¢ half of the mitochondrial gene encoding cytochrome oxidase subunit I and 515 bp DNA from the nuclear gene encoding elongation factor 1 alpha. The morphological dataset was a slightly modi®ed version of a previously published dataset. Representatives from all eight recognized species groups of Gerris, as well as six species from three related genera, including Gigantometra gigas, Limnoporus esakii, L. rufoscutellatus, Aquarius najas, A. conformis and A. paludum, were included. Unweighted parsimony analyses of the COI sequences gave a topology with strong support for only those nodes that were already recognized as closely related based on morphological characters. Similar analyses of EF-1a gave a cladogram with a topology quite different from that based on morphology and COI. Unweighted parsimony analyses of the`total evidence' dataset largely supports the traditional view of Gerris phylogeny. Finally, the implications of the reconstructed phylogeny in relation to biogeography and ecological phylogenetics of Gerris is discussed. # 2001 Blackwell Science Ltd 241 Systematic Entomology (2001) 26, 241±254 Systematic Entomology (2001) 26, 241±254 X Fig. 2. Number of inferred steps based on Fig. 1 against uncorrected (p) distances for pairwise comparisons between 820 bp nucleotide sequences of COI in PAUP*.
We examined the phylogeny of Mantophasmatodea from southern Africa (South Africa, Namibia) using ... more We examined the phylogeny of Mantophasmatodea from southern Africa (South Africa, Namibia) using approx. 1300 bp of mitochondrial DNA sequence data from the genes encoding COI and 16S. The taxon sample comprised multiple specimens from eight described species (Namaquaphasma ookiepense, Austrophasma rawsonvillense, A. caledonense, A. gansbaaiense, Lobatophasma redelinghuysense, Hemilobophasma montaguense, Karoophasma botterkloofense, K. biedouwense) and four undescribed species of Austrophasmatidae; three specimens of Sclerophasma paresisense (Mantophasmatidae); and two specimens of Praedatophasma maraisi and one of Tyrannophasma gladiator (not yet convincingly assigned to any family). For outgroup comparison a broad selection from hemimetabolous insect orders was included. Equally weighted parsimony analyses of the combined COI + 16S data sets with gaps in 16S scored as a fifth character state supported Austrophasmatidae and all species and genera of Mantophasmatodea as being monophyletic. Most species were highly supported with 98-100% bootstrap/7-39 Bremer support (BS), but K. biedouwense had moderate support (87/4) and A. caledonense low support (70/1). Mantophasmatodea, Austrophasmatidae, and a clade Tyrannophasma gladiator + Praedatophasma maraisi were all strongly supported (99-100/12-25), while relationships among the two latter clades and Mantophasmatidae remain ambiguous. Concerning the relationships among genera of Austrophasmatidae, support values are moderately high for some nodes, but not significant for others. We additionally calculated the partitioned BS values of COI and 16S for all nodes in the strict consensus of the combined tree. COI and 16S are highly congruent at the species level as well as at the base of Mantophasmatodea, but congruence is poor for most intergeneric relationships. In forthcoming studies, deeper relationships in the order should be additionally explored by nuclear genes, such as 18S and 28S, for a reduced sample of specimens.
Page 1. Phylogeny of the water strider genus Aquarius Schellenberg ... We examined phylogenetic r... more Page 1. Phylogeny of the water strider genus Aquarius Schellenberg ... We examined phylogenetic relationships among gerrid water striders of the genus Aquarius Schellenberg using molecular and morphological characters. ...
Pumas occupy the largest latitudinal range of any New World terrestrial mammal. Human population ... more Pumas occupy the largest latitudinal range of any New World terrestrial mammal. Human population growth and associated habitat reduction has reduced their North American range by nearly two-thirds, but the impact of human expansion in Central and South America on puma populations is not clear. We examined mitochondrial DNA diversity of pumas across the majority of their range, with a focus on Central and South America. Four mitochondrial gene regions (1140 base pairs) revealed 16 unique haplotypes differentiating pumas into three
Incongruence among trees reconstructed with different data may stem from historical (gene tree-sp... more Incongruence among trees reconstructed with different data may stem from historical (gene tree-species tree conflict) or process (character change biases) phenomena. Regardless of the source, incongruent data, as determined with ''global'' measures of homoplasy, have often been excluded from parsimony analysis of the combined data. Recent studies suggest that these homoplasy measures do not predict the contribution of each character to overall tree structure. Branch support measures identify, on a character to node basis, sources of support and conflict resulting from a simultaneous analysis of the data. We implement these branch support measures to identify sources of character conflict in a clade of water striders consisting of Gerris Fabricius, Aquarius Schellenberg, and Limnoporus St a al species. Separate analyses of morphology, mitochondrial cytochrome oxidase I (COI), large mitochondrial ribosomal subunit (16SrRNA), and elongation factor-1a (EF-1a) data resulted in cladograms that varied in resolution and topological concordance. Simultaneous analysis of the data resulted in two trees that were unresolved for one node in a strict consensus. The topology agreed with current classification except for the placements of Aquarius chilensis and the Aquarius remigis species group closer to Gerris than to congeneric species. Branch support measures indicated that support derived from each data set varied among nodes, but COI had an overall negative effect on branch support. However, Spearman rank correlation of partitioned branch support values indicated no negative associations of branch support between any data sets and a positive association between EF-1a and 16SrRNA. Thus incongruence among data sets was not drastic and the gene-tree versus species tree phenomenon was not implicated. Biases in character change were a more likely reason for incongruence, although saturation curves and incongruence length difference for COI indicated little potential for homoplasy. However, a posteriori inspection of COI nucleotide change with reference to the simultaneous analysis tree revealed AT and codon biases. These biases were not associated with branch support measures. Therefore, it is difficult to predict incongruence or identify its cause. Exclusion of data is ill advised because every character is potentially parsimony informative.
We investigated phylogenetic relationships among pond skaters (Heteroptera: Gerridae) of the genu... more We investigated phylogenetic relationships among pond skaters (Heteroptera: Gerridae) of the genus Limnogonus Stål 1868 by performing separate and combined parsimony analyses of DNA sequences from three mitochondrial (COI + II, 16SrRNA) and one nuclear (28SrRNA) gene(s). The taxon sample represented almost two thirds of the known diversity, and with most taxa represented by two or more individuals. A simultaneous analysis of all data showed that L. luctuosus Montrousier 1865 was paraphyletic and suggests that ''L. luctuosus" from Australia and possibly also a population from the Society Islands (Moorea) each represents unrecognized species. L. fossarum F. 1775 was strongly supported, but the two subspecies L. f. fossarum F. 1775 and L. f. gilguy Andersen and Weir 1997 were paraphyletic. The two currently recognized subgenera Limnogonus (s. str.) Stål 1868 and L. (Limnogonoides) Andersen 1975 were paraphyletic, and were accordingly broken up in several monophyletic groups, each containing one or more species. From Limnogonus
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