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Water Strider Fauna and its Phylogenetic Relationship in Tehsil Wazirabad
Abstract
This examination is intended to investigate the water strider fauna and their phylogenetic relationship in Tehsil Wazirabad, Punjab, Pakistan. Being a decent predator of mosquitoes and successful bioindicator of substantial metal contamination it assumes the imperative job to keep up the manageability of the biological system. The examples of water strider bug were gathered from different oceanic locales during summer and spring from 2018-2019 in Wazirabad City. The type of water strider that was distinguished during this exploration is Aquarius adelaidis (Zettel) having a place with distinct genera Aquarius of the family Gerridae. It likewise uncovered that Aquarius adelaidis disengaged from Wazirabad area has homology a with arrangement of water strider detailed from Cyprus island situated in the northeastern piece of the Eastern Mediterranean. The arrangement examination found that cytochrome c oxidase subunit I is profoundly monitored locale inside all Aquarius species around the world, and is less inclined to varieties and transformations. Aquarius adelaidis is increasingly bountiful with 58.2% of complete assortment.
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Insects and arachnids display the most impressive diversity of mating and social behaviour among all animals. This book investigates sexual competition in these groups, and the variety of ways in which males and females pursue, persuade, manipulate, control and help one another, enabling us to gain a better understanding of how conflicts and confluences of interest evolve together. Each chapter provides a comprehensive review of mating systems in particular insect and arachnid groups, discusses intrinsic and extrinsic factors responsible for observed mating strategies, and suggests fruitful avenues for further research. The book culminates in a synthesis, reviewing the date in terms of the theory of sexual conflict. This broad-based book will be of immense value to students and researchers interested in reproductive strategies, behavioural ecology, entomology and arachnology.
We examined phylogenetic relationships among gerrid water striders of the genus Aquarius Schellenbrg using molecular and morphological characters. The molecular data sets included 780 bp sequence data from the mitochondrial gene encoding cytochrome oxidase subunit I (COI), and 515 bp sequence data from the nuclear gene encoding elongation factor 1 alpha (EF-1 alpha). The morphological data set was a slightly modified version of a previously published data set. We included all 17 known species and one subspecies of Aquarius as well as five species from three related genera, Gigantometra gigas, Limnoporus esakii, L, rufoscutellatus, Gerris pingreensis, and G. lacustris. Unweighted parsimony analyses of the COI data set gave a single most parsimonious tree (MPT) with a topology quite similar to the morphological tree. Parsimony analyses of the EF-1 alpha data set gave 3 MPT's and a strict consensus of these trees gave a tree with a slightly different topology. A combined analysis of the three data sets gave a single MPT with the same topology as for the morphological data set alone. The phylogeny of Aquarius presented here supports the monophyly of the A. najas, remigis, conformis and paludum species groups as well as previous hypotheses about their relationships. On the other hand, the inclusion of molecular data weakens the support for the monophyly of the genus Aquarius, and questions the specific status of the eastern North American A. nebularis (as separate from A. conformis) and members of the Nearctic A. remigis group. Finally, we discuss the implications of the reconstructed phylogeny in the biogeography and ecological phylogenetics of Aquarius.
Males of the water strider Gerris odontogaster have two abdominal ventral processes (MAPs) that provide a posterior attachment to females during mating. Females were reluctant to mate, and the MAPs were important for males to succeed in copulations. Low male mating success and absence of second male take-over attempts during mating, suggested the functional significance of the processes to be intersexual rather than intrasexual. The length of MAPs varied considerably in the studied population (range 0.08-0.22 mm, CV = 15.4%). Laboratory experiments showed that males with longer MAPs had a greater ability to endure females' rejection behaviour than males with shorter MAPs. The mating and non-mating fractions of a natural population significantly differed in length of MAPs, thus indicating sexual selection in the field. The heritability of process length was high, contrary to what is predicted by classic quantitative genetic theory for important fitness traits.
Genetic diversity and phylogeography was examined in a survey of 769 bp of COI mtDNA from multiple representatives of fi ve Palaearctic water strider species with diff erent habitat preferences, phenologies and frequencies of various wing morphs: Aquarius najas (DeGeer, 1773), A. paludum (Fabricius, 1794); Gerris lacustris (Linnaeus, 1758), G. costae (Herrich-Schaeffer, 1850) and G. thoracicus Schummel, 1832. Comparisons of uncorrected p sequence divergences with standard deviations showed signifi cant diff erences between the fi ve species with Aquarius najas being the most diverse species (>2%), followed by A. paludum and Gerris lacustris with intermediate diversity (~1%), and with G. costae and G. thoracicus showing the lowest sequence diversity (<0.5%). As expected there was a strong negative correlation between the frequencies of macropterous individuals and the amount of sequence divergences. When sequence divergences were displayed as a distance tree it was shown that Aquarius najas showed most spatial variation hereby indicating a high degree of geographi-cal isolation especially around the Mediterranean Sea; Gerris lacustris had deep sequence divergences in Turkey and Armenia, and Aquarius paludum, Gerris costae and G. thoracicus all have shallow divergences and no geographical structure. Th e results are used to discuss molecular markers, species taxonomy, Pleistocene refugia and postglacial dispersal routes. S. Grozeva & N. Simov (eds.) 2008. ADVANCES IN HETEROPTERA RESEARCH Festschrift in Honour of 80th Anniversary of Michail Josifov, pp. 1-4.
Conflict between the sexes over control of copulation may drive the coevolution of elaborate genitalia and other secondary sexual structures. Support for this hypothesis is limited to male adaptations that function to enhance male control over females in copulation (e.g. structures that function to clasp females). Evidence for morphological adaptation in females is critical to the hypothesis, yet lacking. Here, we present the first experimental evidence demonstrating that female abdominal spines in water striders function to increase female control over copulation. By experimentally extending the phenotypic size range of these spines, we show that this morphological adaptation, specific to females, allows them to thwart harassing males, and as a result, reduce the frequency of costly matings to females. This demonstrates the coevolutionary nature of sexual conflict and that females are indeed active participants in the evolutionary conflict over control of reproduction.
Although cytonuclear incompatibilities between species have been implicated in a variety of theoretical and experimental studies, the influence of such fitness interactions on gene introgression has been demonstrated in very few hybrid zones. We examined patterns of introgression between two species of Limnoporus Stål, 1868 water striders from 10 populations transecting a hybrid zone in Alberta and British Columbia. DNA-sequence variation in mitochondrial locus COI was compared with two nuclear loci, EF1-α and ITS 1. The spatial distribution of haplotype lineages showed strong barriers to gene exchange for mtDNA. Constraints on introgression were weaker for the nuclear markers, particularly ITS 1. The mtDNA from Limnoporus dissortis Drake and Harris, 1930 was associated with nuclear genes from Limnoporus notabilis Drake and Hottes, 1925 less often than expected by random mating, indicating that some cytoplasmic and nuclear combinations are favored over others and that cytonuclear incompatibilities play a role in structuring this hybrid zone. Mitochondrial mobility across the hybrid zone is likely to be restrained by the unusual hybrid inviability of these species. In a reversal of the pattern expected on the basis of Haldane's rule, females are the XX sex and yet hybrid females are much more inviable than males. Differential removal of hybrid females, which carry mtDNA, can explain disproportionately low mitochondrial introgression across the hybrid zone.
The six extant species of Limnoporus water striders provide an unusual opportunity to compare allozyme and mitochondrial DNA (mtDNA) divergences with both morphological divergences and information on interspecific hybrid inviability. Parsimony analyses of mtDNA, allozymes, and morphology did not differ greatly, and each data type provided useful information on at least some nodes in the phylogeny. Simultaneous analysis of the combined data gave a better resolved and supported tree than did any single data type. Several measures of hybrid inviability bore no relationship to genetic distances between species, thus demonstrating the poor value of hybrid compatibility as an indicator of phylogenetic relationships. When genetic distances were related to estimates of time of divergence based on fossils, standard molecular clocks for mtDNA and allozymes showed as much as a 10-fold underestimate of absolute time. The phylogeny of Limnoporus allows more rigorous evaluation of several prior hypotheses of ecological or developmental processes in water striders. In particular, the phylogeny supports the evolutionary lability of wing dimorphism, sexual size dimorphism, and local differentiation of ontogenetic traits.
This study addresses the phylogenetic relationships within and between two widespread Palaearctic pond skater species, Gerris costae and G. thoracicus, by including new DNA sequence data from the Central Asian G. sahlbergi, traditionally assigned as a close relative of G. costae. The results support the assignment of G. costae and G. thoracicus to two individual species groups that are not closely related, but also that G. sahlbergi is nested within G. costae (including subspecies costae, fieberi and poissoni) thus suggesting a new subspecific rank as G. c. sahlbergi. A broad geographical sampling of mitochondrial DNA from populations of G. thoracicus and G. costae (incl. G. c. sahlbergi) shows that the two species are strikingly similar in terms of genetic diversity and lack of geographical substructure, thus adding further evidence for the G. costae group comprising a single, widespread species.
The genetic diversity and phylogeny of western Palaearctic members of the Gerris lacustris group was investigated on the basis of 822 bp from the 3´end of the mitochondrial gene encoding COI obtained from 34 specimens of G. lacustris, 16 specimens of G. gibbifer, eight specimens of G. maculatus and seven specimens of G. brasili. Nine haplotypes represented G. lacustris, nine haplotypes represented G. gibbifer, six haplotypes represented G. maculatus, four haplotypes represented G. brasili, and a single haplotype was shared between G. gibbifer and G. brasili. Uncorrected p genetic distances within species averaged from 0.5% in G. gibbifer and G. brasili to 0.8 in G. lacustris and as much as 2.2 in G. maculatus. A phylogenetic analysis showed that G. gibbifer and G. brasili are not reciprocally monophyletic in their mtDNA probably due to relatively recent speciation and incomplete lineage sorting. G. maculatus was poorly supported as the sister taxon to G. gibbifer and G. brasili despite morphological similarities, and a clear division between G. maculatus populations in the eastern and western Mediterranea, may indicate different refugia during the Pleistocene glaciations. G. lacustris showed little genetic substructure except for some isolated haplotypes in Italy, Turkey and Armenia, but these are geographically overlapping with more widespread haplotypes, and probably represent more ancient diversities in these regions.
Phylogeny of the semiaquatic bugs (Hemiptera-Heteroptera, Gerromorpha) JAKOB DAMGAARD Damgaard, J.: Phylogeny of the semiaquatic bugs (Hemiptera-Heteroptera, Gerromorpha). Insect Syst. Evol. 39: 431-460. Copenhagen, November 2008. ISSN1399-560X. The phylogeny of semi-aquatic bugs (Hemiptera-Heteroptera: Gerromorpha) was tested in parsimony analyses of 64 morphological characters and approximately 2.5 kb of DNA sequence data from the mitochondrial genes encoding COI+II and 16SrRNA and the nuclear gene encoding 28SrRNA. The taxon sample included representatives of all families and most subfamilies of Gerromorpha and a selection of outgroup taxa representing the two basal infra-orders of Heteroptera, Enicocephalomorpha and Dipsocoromorpha, and two families of Nepomorpha. A simultaneous analysis (SA) of all data, and with gaps scored as fifth state characters, gave a single most parsimonious tree with all families resolved as monophyletic, except the Veliidae, where Microveliinae + Haloveliinae, Veliinae, Rhagoveliinae, Perittopinae, and Ocelloveliinae were resolved as successive sister groups to the Gerridae, thus confirming earlier statements about paraphyly of this family. The Gerridae + Veliidae clade was strongly supported, but otherwise only the Gerridae + Veliidae less Ocelloveliinae and the Gerridae itself had support. These three clades could all be diagnosed on apomorphic morphological characters, although no characters diagnosing the Gerridae were without con-vergences or present in all included taxa. While the Ocelloveliinae, Veliinae and Haloveliinae could not be diagnosed on convincing apomorphies, the Microveliinae + Haloveliinae, and their sister group relationship with the Gerridae, could be diagnosed on rather strong morpho-logical synapomorphies, suggesting that Gerridae could be expanded to include these two veli-id subfamilies, while Ocelloveliinae, and perhaps the remaining veliid subfamilies, could be elevated to new families. In Gerridae, the Ptilomerinae + Halobatinae was sister group to all other subfamilies, while the Rhagadotarsinae + Trepobatinae was sister group to a clade com-prising the Gerrinae, Eotrechinae, Cylindrostethinae and Charmatometrinae. Most relation-ships in this clade were poorly supported and diagnosed, and Cylindrostethinae was surpris-ingly found to be paraphyletic. The sister group to the Gerridae + Veliidae clade was a strong-ly supported clade comprising the Paraphrynoveliidae and Macroveliidae, and this, and the lack of convincing synapomorphies for Paraphrynoveliidae, suggest that these two small fam-ilies could be synonymized. For the basal relationships of Gerromorpha, the Mesoveliidae was strongly supported sister group to all other families, while the Hebridae, Hermatobatidae and Hydrometridae formed a poorly supported and poorly diagnosed sister group to the Gerridae + Veliidae + Paraphrynoveliidae + Macroveliidae clade. The unexpected sister group relation-ship between Hermatobatidae and Hydrometridae was moderately supported, and could be diagnosed on two synapomorphies, thus giving a new hypothesis about the relationships of these very divergent families. Phylogenetic analyses of individual character partitions gave less resolved and less supported relationships, and the mitochondrial genes COI+II and 16SrRNA contributed negative hidden partitioned Bremer support (HPBS) to the simultane-ous analysis tree, probably due to homoplasy caused by saturation effects.
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 mitochondria! 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 resolved and better supported tree than did analyses of any single data set. The phytogeny of Halobates presented here allows a more rigorous evaluation of several prior hypotheses about evolutionary processes in marine water striders. In particular, it supports the hypothesis of at least two separate transitions from coastal to oceanic environments.
We investigated phylogenetic relationships of water striders (Hemiptera-Heteroptera: Gerridae) from the three principal Holarctic genera, Aquarius Schellenberg, Limnoporus Stål and Gerris Fabricius with parsimony analyses of sixty-six morphological characters and DNA sequences from mitochondrial (cytochrome c oxidase subunit I + 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 + 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.
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 Stål species. Separate analyses of morphology, mitochondrial cytochrome oxidase I (COI), large mitochondrial ribosomal subunit (16SrRNA), and elongation factor-1α (EF-1α) 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-1α 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.
Relatively few insects have invaded the marine environment, and only five species of sea skaters, Halobates Eschscholtz (Hemiptera: Gerridae), have successfully colonized the surface of the open ocean. All five species occur in the
Pacific Ocean, H. germanus White also occurs in the Indian Ocean, whereas H. micans Esch- scholtz is the only species found in the Atlantic Ocean. We sequenced a 780 bp long region of the mitochondrial cytochrome
oxidase subunit I gene (COI) for a total of 66 specimens of the five oceanic Halobates species. Our purpose was to investigate the genetic variation within species and estimate the amount of gene flow between
populations. We defined 27 haplotypes for H. micans and found that haplotype lineages from each of the major oceans occupied by this species are significantly different, having
sequences containing five to seven unique base substitutions. We conclude that gene flow between populations of H. micans inhabiting the Atlantic, Pacific, and Indian Ocean is limited and hypothesize that these populations have been separated
for 1 to 3 million years. Similarly, there may be limited gene flow between H. germanus populations found in the Pacific and Indian Ocean and between H. sericeus populations inhabiting the northern and southern parts of the Pacific Ocean. Finally, we discuss our findings in relation
to recent hypotheses about the influence of oceanic diffusion on the distribution and population structure of oceanic Halobates spp.
Insect molecular systematics has undergone remarkable recent growth. Advances in methods of data generation and analysis have led to the accumulation of large amounts of DNA sequence data from most major insect groups. In addition to reviewing theoretical and methodological advances, we have compiled information on the taxa and regions sequenced from all available phylogenetic studies of insects. It is evident that investigators have not usually coordinated their efforts. The genes and regions that have been sequenced differ substantially among studies and the whole of our efforts is thus little greater than the sum of its parts. The cytochrome oxidase I, 16S, 18S, and elongation factor-1 alpha genes have been widely used and are informative across a broad range of divergences in insects. We advocate their use as standards for insect phylogenetics. Insect molecular systematics has complemented and enhanced the value of morphological and ecological data, making substantial contributions to evolutionary biology in the process. A more coordinated approach focused on gathering homologous sequence data will greatly facilitate such efforts.
Cryptovelia terrestris n. gen., n. sp. (Brazil), Darwinivelia fosteri n. gen., n. sp. (Galapagos Is.), Mniovelia kuscheli n. gen., n. sp. (New Zealand), and Cavaticovelia n. gen. (type-species: Speovelia aaa Gagné & Howarth, 1975; Hawaii) are described. The phylogenetic relationships between the mesoveliid genera are discussed in the light of characters revealed by the new taxa. Habitat preferences of mesoveliids include humid terrestrial and/or marginal aquatic habitats, which probably are the most ancestral, and lava-tubes, coastal caves, intertidal marine habitats, and the plant-covered freshwater surface, which probably are the derived kinds of habitats. A classification of the Mesoveliidae with a check list of genera and species is presented. Two subfamilies are recognized: Madeoveliinae (with two genera) and Mesoveliinae (seven genera). The biogeography of the Mesoveliidae is finally discussed.
1. We used mtDNA sequence variation to estimate population genetic structure between and among water strider populations of Potamobates williamsi and P. sumaco in the Ecuadorian Amazon.
2. Sequencing of the COI mitochondrial gene revealed 16 haplotypes, which were summarised into four haplotype groups. P. williamsi and P. sumaco shared two common and widespread haplotypes.
3. Population structure was moderate and gene flow was low. Both air and river distances were significantly correlated with gene flow and, thus, indicative of isolation by distance.
4. The genetic structure within and among populations of P. williamsi and P. sumaco was probably not influenced by the dynamic tropical lotic system.
Five species of sea skaters, genus Halobates Eschscholtz, are the only insects to have successfully colonized the open ocean. In addition, 36 species are found in sheltered coastal waters throughout tropical Indo-Pacific. The taxonomy of the genus is relatively well known, but reliable hypotheses about phylogenetic relationships are required if the biogeography and evolution of sea skaters is to be discussed in a meaningful way. This work presents the results of a study of new characters from the genital segments, especially those of the male phallus and the female gynatrial complex, and a reinterpretation for several other characters. In total 64 characters were scored for 26 species of Halobates, two species ofAsclepios and one species of Metrocoris. With Asclepios and Metrocoris species as outgroups, the character state sets were analysed cladistically using the computer program Hennig86. After critical evaluations of both characters and clades, a phylogeny for Halobates is presented and its taxonomic implications are discussed. A number of monophyletic species groups are delimited. One genus-level synonymy and three species-level synonymies are suggested. The evolution of Halobates is discussed in the light of the reconstructed phylogeny and present knowledge of the ecology and behaviour of sea skaters. A hypothesis of ecological evolution in halobatine water striders is proposed and tested.
Where the distribution ranges of the waterstriders Limnoporus notabilis and L. dissortis meet in western Canada, extensive hybridization and introgression occurs. Multivariate ordination analyses of genetic and morphometric data by principal component analysis revealed that a single axis separating the two parent species could account for nearly all the variation in both data sets. Maps of principal component scores for both data sets revealed geographical patterns of variation reflecting specific topographic features in the region. Comparisons of morphometric data from some of the samples collected in the 1980s and from the same sites revisited in the 1990s revealed substantial changes. An ‘island’ of dissortis-like populations inside the range of L. notabilis in interior British Columbia expanded, and a marked local protrusion of notabilis-like phenotypes into the range of L. dissortis on the east slope of the Rocky Mountains diminished during the decade between collections. We conclude that introgressive hybridization between these two species of waterstriders is a spatially complex and highly dynamic process.
The aquatic and semi-aquatic Heteroptera, consisting of the infraorders Leptopodomorpha, Gerromorpha, and Nepomorpha, comprise
a significant component of the world’s aquatic insect biota. Within these three infraorders as a whole there are currently
23 families, 343 genera and 4,810 species group taxa considered valid, of which 20 families, 326 genera and 4,656 species
inhabit freshwater. In addition, more than 1,100 unequivocally diagnosed species remain to be described. Aquatic Heteroptera
occur on all continents except Antarctica, and are most numerous in the tropical regions, although there are many distinctly
cold-adapted genera. Overall species richness is highest in the Neotropical and Oriental regions, which harbor 1,289 and 1,103
species, respectively. In comparison to these core tropical regions, species richness is significantly lower in the Afrotropical
(799 species), Australasian (654 species), Palearctic (496 species), Nearctic (424 species) and Pacific (37 species) regions.
Aquatic Heteroptera are notable for utilizing an exceptionally broad range of habitats, from marine and intertidal to arctic
and high alpine, across a global altitudinal range of 0–4,700m. Species may be found in almost every freshwater biotope,
and many exhibit striking morphological adaptations to their aquatic environment, making them excellent subjects for ecological
and biogeographic studies.
Andersen, N. M. (Zoological Museum, University of Copenhagen, Universitetsparken 15 DK-2100 Copenhagen, Denmark) 1979. Phylogenetic inference as applied to the study of evolutionary diversification of semiaquatic bugs (Hemiptera: Gerromorpha). Syst. Zool. 28:554–578 .—The possibility of deciphering patterns of evolutionary diversification using the semiaquatic bugs (Hemiptera: Gerromorpha) as an example group is examined. Two different approaches are contrasted: the evolutionary systematic and the phylogenetic (cladistic) approach. The methods of phylogenetic inference are thereafter applied to data on the structural, behavioral, and ecological divesity of semiaquatic bugs. Semiaquatic bugs comprise an unusual life form as they are the most successful group of insects inhabiting the water surface in almost any kind of habitat, including the open ocean. Semiaquatic bugs are currently classified in eight families: Mesoveliidae, Hebridae, Paraphrynoveliidae, Macroveliidae, Hydrometridae, Her-matobatidae, Veliidae, and Gerridae. A cladogram of relationships among these families is constructed. It provides a hypothesis about the sequence of branching in evolution corroborated by synapomorphic characters. An estimate of the amount of evolutionary change within single lineages (derivation load) is introduced. The habitat preferences of semiaquatic bugs are superimposed upon the cladistic relationships among taxa. Phylogenetic inferences suggest that the ancestral type of habitat of most families was humid terrestrial and/or marginal aquatic. Species belonging to most families have remained in the ancestral habitats and a few species of the Veliidae and Gerridae have secondarily invaded similar habitats. Derived habitats include the plant-covered water surface, the free surface of stagnant fresh water, flowing fresh water, intertidal marine waters, and the surface of the open ocean. Each of these categories of habitats has been independently invaded several times from more ancestral habitats. Several adaptive features of semiaquatic bugs are discussed and their ancestral and derived states separated. There are definite associations between the physical nature of the environment and the structural, mechanical, and behavioural elements of locomotion. The evolutionary transition from the walking rhythm of leg movements towards the rowing rhythm and locomotion by jump-and-slide movements has probably taken place several times. Two different kinds of predator strategies in semiaquatic bugs can be distinguished: that of a searching predator, which is the most ancestral, and that of a waiting predator utilizing surface ripples in prey-location, which is the derived strategy. Wing polymorphism, sexual behaviour of surface-inhabiting bugs, and diversification of the egg system are also discussed. The evolutionary diversification of semiaquatic bugs is visualized as a repeated series of transitions between a hygropetric and a pleustonic adaptive zone and adaptive radiation towards various subzones of the latter. This model has some weaknesses from an ecological point of view. Ecological diversification is not just a problem of the relations between structure and environment. The limited supply of resources, conflicting demands of various factors, and interspecific competition and/or predation may be important as well. In conclusion, the neo-Darwinian views on the origin and differentiation of higher taxa are examined and criticized.
Australian water bugs, their biology and identification (Hemiptera-Heteroptera
- N M Andersen
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Phylogeny and reclassifi cation of species groups in Aquarius Schellenberg
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Damgaard, J. & A. I. Cognato (2005). Phylogeny and reclassifi cation of species groups in Aquarius Schellenberg,
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A review of the veliid fauna of bromeliads, with a key and description of a new species
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