Review of morphological evidence on the phylogeny of basal Hymenoptera (Insecta), with a discussion of the ordering of characters

In a previous study of the phylogeny of basal Hymenoptera, Vilhelmsen (2001; Zool. J. Linn. Soc . 131 : 393–442) compiled an extensive morphological data matrix for a phylogenetic analysis of basal Hymenoptera, comprising 38 hymenopteran genera. In this study, his characters are revised. This results in a cladogram whose relationships largely agree with those proposed by Vilhelmsen, except that the relationships at the base of the Hymenoptera are unresolved. The revised data matrix is expanded by 17 sawfly and three apocritan taxa. Moreover, 112 new morphological characters from different parts of the larval and adult morphology are also added to the data matrix, including 82 from a recent study of the terminal abdominal segments of male Hymenoptera. The addition of the new characters leads to Xyelidae, again, being the sister-group of all other Hymenoptera. The relationships among the sawfly families as proposed by Vilhelmsen are confirmed, except that the relationships among Syntexis , Siricidae and Xiphydriidae + Vespina are unresolved and that the monophyly of Apocrita is not convincingly supported. A separate analysis is performed which includes all extant genera of Xyelidae. The internal phylogeny of Xyelidae is determined as (( Macroxyela Megaxyela ) Xyelecia ( Xyela Pleroneura )).  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 79 , 209–243.     

Simultaneous analysis of basal Hymenoptera (Insecta): introducing robust-choice sensitivity analysis

Molecular characters are analysed on their own and in combination with morphological data to examine the phylogenetic relationships of the basal lineages of Hymenoptera ('Symphyta'). This study covers 47 sawfly genera and nine apocritan families and includes molecular sequences from five genes − 12S, 16S, 18S and 28S ribosomal genes and cytochrome oxidase 1 − as well as 343 morphological characters. A robust-choice sensitivity analysis is performed with the data. First, the simultaneous analysis is repeated three times, each time employing a different step matrix for weighting the transformations of the molecular characters. Then, the results of all three simultaneous analyses are summarized in a strict consensus in order to avoid basing the conclusions on a narrow set of assumptions. This methodology is discussed in the paper. The relationships among superfamilies largely confirm previous hypotheses, being (Xyeloidea (Tenthredinoidea s.l. (Pamphilioidea (Cephoidea (Siricoidea (Xiphydrioidea (Orussoidea Apocrita))))))), where Siricoidea is understood as Siricidae+Anaxyelidae. However, the relationships within Tenthredinoidea s.s. proposed here are novel: ({Argidae Pergidae}[ Athalia {(Diprionidae Cimbicidae) Tenthredinidae minus Athalia }]).  © 2003 The Linnean Society of London . Biological Journal of the Linnean Society , 2003, 79, 245–275.     

Evolution probing for semiochemicals based on secondary metabolites in the cuticles of three species of Halobates (Heteroptera: Gerridae)

We developed methods for characterizing semiochemicals in the cuticles of the sea-skater Halobates (Gerridae). Such substances may be involved in chemical communication at the sea surface and have been shown to act as sexual pheromones for a related marine insect Trochopus plumbeus (Veliidae). We identified 86 volatile compounds in extracts from three Halobates species ( H. micans Eschscholtz, H. hawaiiensis Usinger and H. sobrinus White) and used them to reconstruct the phylogeny of the clade. Sixty-seven of the compounds were found to be parsimony-informative. Suspected semiochemicals appear to be specific autapomorphies in the phylogram, and our results indicated that chemical profiles may be used to predict the phylogenetic history of Halobates . Moreover, the phylogenetic tree derived from our data is congruent with a previously published one based on morphology and mitochondrial DNA sequence (780 bp in the COI gene). The potential role of each compound to be used for chemical communication was also reviewed. At appropriate concentrations, some of the cuticular compounds, being partly hydrophobic and partly hydrophilic, could disperse on the sea surface and thereby play an energetically efficient role in chemical communication, e.g. mate location. Less dispersible components might act as 'sun-screens' and provide protection from UV-irradiation during daylight hours.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 671–688.     

A new phylogenetic classification for the gymnophthalmid genera Cercosaura , Pantodactylus and Prionodactylus (Reptilia: Squamata)

Because of the poor state of knowledge of many of the gymnophthalmid genera, systematic revision is necessary to render the classification consistent with evolutionary history. To that end, I conducted a review of the species of three genera of the Cercosaurinae which appear to form a monophyletic group: Cercosaura , Pantodactylus , and Prionodactylus . Phylogenetic analysis of 61 morphological characters was conducted after specimens of all species were examined to evaluate the composition of each taxon. The phylogenetic reconstruction suggested that the genus Prionodactylus was paraphyletic. A new phylogenetic classification is proposed that synonymizes Pantodactylus and Prionodactylus with Cercosaura. Cercosaura is redefined to include 11 species and seven subspecies. A key is provided to distinguish among species.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 137 , 101−115.     

Evolution and determinants of host specificity in the genus Lamellodiscus (Monogenea)

The evolution and determinants of host specificity in Lamellodiscus species (Monogenea, Diplectanidae) were investigated. The 20 known Mediterranean species were studied, all parasites of fishes from the family Sparidae (Teleostei). An index of specificity, which takes into account the phylogenetic relationships of their fish host species, was defined. The link between specificity and its potential determinants was investigated in a phylogenetic context using the method of independent contrasts. Host specificity in Lamellodiscus species appeared to be highly constrained by phylogeny, but also linked to host size. Mapping specificity onto the parasite phylogenetic tree suggests that specialist species do not represent an evolutionary dead end, and that specialization is not a derived condition. It is hypothesized that the ability to be generalist or specialist in Lamellodiscus is controlled by intrinsic, phylogenetically-related characteristics, and that specialist species tend to use large hosts, which may be more predictable.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77, 431−443.     

The evolution of venom-delivery systems in snakes

The Colubroidea represents approximately 2300 of the 2700 species of living snakes and includes all venomous taxa. Although many morphological studies of colubroid snakes have been carried over the last hundred years, the phylogenetic relationships within this group are poorly known. In this study, components of the venom-delivery system (VDS) were examined within the context of two conflicting phylogenetic hypotheses proposed in 1988 by Cadle and in 1998 by Kraus & Braun. The results suggest that several major morphological changes occurred early in colubroid evolution: a Duvernoy's gland evolved, the posterior maxillary teeth became specialized relative to the anterior maxillary teeth, and the attachment of the pterygoideus muscle moved forward to a position associated with the posterior maxillary teeth. These innovations may have allowed the great radiation of colubroid snakes that led to the Colubroidea representing such a large percentage of living snakes. More recently, three separate lineages of colubroids have independently evolved highly specialized front-fanged VDSs with large and complex venom glands, venom gland compressor muscles, and tubular fangs.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 137 , 337−354.     

Phylogenetic analysis of Russian Permian dicynodonts (Therapsida: Anomodontia): implications for Permian biostratigraphy and Pangaean biogeography

Dicynodont therapsids have been known from the Upper Permian of Eastern Europe since the beginning of the twentieth century, but the phylogenetic relationships of these taxa have not been examined cladistically. Here we present the results of a phylogenetic analysis that includes eight Permian dicynodonts from Russia as well as 18 taxa best known from southern Africa. Our results do not conflict with much of the established picture of Permian dicynodont phylogeny, but are consistent with several novel hypotheses. Most importantly, our analysis suggests that the genus Dicynodon is paraphyletic, and we question its use in correlating widely separated basins. However, we cannot strongly reject a monophyletic Dicynodon . Our results also indicate that the closest Permian relatives of Kannemeyeria lived in Russia, suggesting a Laurasian origin for the lineage that includes this important Triassic taxon. The phylogeny presented here also suggests a Laurasian origin for several other dicynodont clades, but a Gondwanan origin is equally likely given the data at hand. Regardless of where these groups originated, there appears to be some endemism among Late Permian dicynodont faunas. Although our understanding of dicynodont phylogeny is improving, this study emphasizes the disparity in sampling of the dicynodont record between Gondwana and Laurasia and the need for a large scale phylogenetic analysis of Permian and Triassic dicynodonts.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society, 2003, 139 , 157−212.     

On the systematic status of the desert plated lizard (Angolosaurus skoogi): phylogenetic inference from DNA sequence analysis of the African Gerrhosauridae

The desert plated lizard ( Angolosaurus skoogi ), a 'sand sea' endemic of the northern Namib Desert, exhibits remarkable morphological convergence with other dune-dwelling lizards worldwide. This distinct ecomorphic condition sets Angolosaurus apart from the remaining genera in the family Gerrhosauridae. Indeed, a morphological phylogeny addressing generic relationships within the Cordyliformes (Cordylidae + Gerrhosauridae) identified Angolosaurus as the earliest diverging taxon among African gerrhosaurids. We re-evaluated the basal status of Angolosaurus , conducting a molecular phylogenetic analysis of the African and Madagascan gerrhosaurid genera. Our survey involved a comprehensive species-level comparison among the four nominal genera of mainland Africa ( Angolosaurus , Cordylosaurus , Tetradactylus and Gerrhosaurus ). Mitochondrial DNA sequence data from the cytochrome b , ND2, 12S and 16S rRNA genes were combined for analysis using both parsimony and maximum likelihood procedures. In contrast to the morphological hypothesis, our results do not depict Angolosaurus as the sister taxon to other African gerrhosaurids. Rather, the molecular analyses consistently place Angolosaurus within Gerrhosaurus , rendering the latter genus paraphyletic.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 253–261.     

Transitions in cuticular composition across a hybrid zone: historical accident or environmental adaptation?

Two subspecies of the grasshopper Chorthippus parallelus form a hybrid zone in the Pyrenees. Transitions across the zone, including changes in mating signals and reproductive isolation have been intensively studied. Cuticular pheromones have been identified as likely mate recognition signals. Since the major role of the cuticle is in waterproofing, environmental adaptation of cuticular composition has the interesting potential to generate assortative mating as an incidental by-product. We describe the pattern of variation in cuticular hydrocarbon blend in four transects through the hybrid zone. We find no evidence for a previously observed displaced cline in one blend component. There were differences between subspecies but these varied among transects and were small compared with variation between transects. We examined environmental variation within one transect and found a correlation between vegetation and cuticular composition, suggesting that environment influences the constitution of the cuticle, and hence natural selection may interact with mating signals in this species.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 78 , 193−201.     

A phylogeny of the families of fossil and extant tetraodontiform fishes (Acanthomorpha, Tetraodontiformes), Upper Cretaceous to Recent

A data matrix is presented of 210 morphological characters (mostly osteological, some external) for 20 extant taxa of the ten Recent families of tetraodontiform fishes and 36 fossil tetraodontiforms. The oldest of these are from the Upper Cretaceous (95 Mya); most are from the Lower to Middle Eocene (50–58 Mya). There are two outgroup taxa (a zeiform and a caproid). A cladistic analysis of this matrix for only the extant taxa produced two equally parsimonious trees that call into question the monophyly of some of the previously accepted major higher-level tetraodontiform clades. Inclusion in the analysis of the large number of available fossil taxa helps to resolve relationships between family level clades. The new phylogenetic hypothesis, together with stratigraphic and biogeographical data, is used to discuss scenarios of the origin and evolution of the major clades of the order.  © 2003 The Linnean Society of London, Zoological Journal of the Linnean Society , 2003, 139 , 565−617.     

Phylogenetics, zoogeography, and the role of dispersal and vicariance in the evolution of the Rana catesbeiana (Anura: Ranidae) species group

The Rana catesbeiana species group consists of seven species, each variously distributed across eastern North America. We estimated the evolutionary relationships among 31 exemplars and used the phylogenetic hypothesis to examine the potential modes of speciation and relative role of dispersal in the evolution and zoogeography of this species group. Phylogenetic relationships based on 1554 combined base pairs of the cytochrome b and ND2 mitochondrial genes suggest that the species are closely related, having undergone rapid radiation from a common ancestor during the late Miocene or Pliocene. A Pleistocene origin for the rare R. okaloosae is suggested by its pattern of paraphyly with R. clamitans and by its geographically restricted distribution, although hybridization as the explanation for paraphyly cannot be ruled out. Dispersal–vicariance analysis suggested a Coastal Plain biogeographical region origin of the species group, supporting the notion that the region was an important centre of anuran diversification, with post-speciation dispersal playing a major role in explaining the distribution of the widespread species, R. catesbeiana , R. clamitans, and R. septentrionalis . High sea levels during the late Tertiary, greatly reducing and insularizing parts of the southern Coastal Plain region may have played a major role in the diversification of this group.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 601–624.     

Ecological diversity and adaptive tendencies in the tropical fern Trichomanes L. (Hymenophyllaceae) with special reference to climbing and epiphytic habits

Among the basal fern families, the Hymenophyllaceae, with more than 600 species, display a high diversity in terms of their morphology and the habitats that they occupy. We have chosen to focus on Trichomanes L., a clearly defined genus for which a phylogeny is presently being developed, to investigate the appearance of the climbing and epiphytic habits, as well as the related supposed adaptive characters. In this study we present the first review of the different ecological types within the genus: terrestrial, climbing (divided into hemi-epiphytic forms and true lianas), and epiphytic types. The study of several features concerning stem morphology and leaf size allows a proposal on relationships between ecology and plant morphology. Terrestrial species display a thick monocaulous rhizome with robust roots and short internodes. Climbing species are characterized by a branched, thick, creeping rhizome with long internodes. Epiphytic species also exhibit long, creeping and branching stems with long internodes but the rhizome is fine to filiform. Under these circumstances, there is a reduction of root system and frond size leading to dwarfism in numerous instances. This may be related to an extreme hygrophilous epiphytic strategy. Finally, hypotheses on the evolution of these habits and hence on the evolutionary relationships between ecology and characters are presented and discussed.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 41–63.     

Can we predict centres of plant species richness and rarity from environmental variables in sub‐Saharan Africa?

In order to investigate continental-scale patterns of plant species richness and rarity, distribution maps of 3661 plant species were digitized into a one degree grid of sub-Saharan Africa using the WORLDMAP computer programme. Cells with high species richness were also likely to be those containing the greatest number of species of restricted range, but areas such as the South African Cape and the Eastern Arc mountains were found to have more restricted-range species than predicted from their richness scores. The two environmental predictors which had the strongest individual relationships with both species richness and range-size rarity were absolute maximum annual temperature and mean monthly potential evapotranspiration. However, correlative predictive powers of these variables were low, with R =−0.58 and R =−0.54, respectively ( P  < 0.01). Multiple regression also failed to produce a strong explanatory model for observed continental-scale patterns of diversity. Spatial variability analysis showed that this was likely to be because different environmental parameters predicted different centres of richness and rarity. West African species richness was better predicted by absolute maximum annual temperature, whereas East African species richness was better predicted by mean monthly potential evapotranspiration.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 187–197.     

The evolution of CAM in the subfamily Pitcairnioideae (Bromeliaceae)

A molecular phylogeny for the subfamily Pitcairnioideae was inferred to examine the distribution of crassulacean acid metabolism in the subfamily. For this purpose, a neighbour-joining tree with p-distances was built using a MatK chloroplast gene data set. The phylogenetic results of our analysis confirmed the monophyletic condition of most genera examined: Brocchinia , Dyckia , Encholirium , Fosterella , Hechtia and Puya . A paraphyletic basal sequence showed Hechtia branching off from the basal node, followed by Brocchinia , Cottendorfia  +  Navia phelpsiae, and Puya . The remaining taxa were divided into two groups: (a) Deuterocohnia meziana , Dyckia , Encholirium ; Fosterella ; Deuterocohnia spp. +  Pitcairnia heterophyla ; (b) Pepinia , Pitcairnia spp. and Navia igneosicola . The basal placement of the CAM genera Hecthia indicates that CAM may be a 'primitive condition' in Pitcairnioideae and that C₃ species may have lost the ability to induce CAM. In this molecular tree, CAM metabolism appeared scattered throughout the tree. Current knowledge, however, does not exclude the possibility that CAM arose only once and it has been switching on and off in various lineages. Further detailed studies on photosynthetic metabolisms and the phylogenetic distribution of characters will provide a better basis on which to evaluate photosynthetic origins.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 261–268.     

Phylogeny of Australasian agamid lizards based on nuclear and mitochondrial genes: implications for morphological evolution and biogeography

Recent mtDNA phylogenies of Australasian agamid lizards are highly incongruent with existing morphological views. To resolve this discrepancy we sequenced two nuclear gene regions, c- mos and brain-derived neurotrophic factor (BDNF). These were highly concordant with each other and the mtDNA phylogeny, but not the morphology. A combined molecular analysis reveals substantial hidden support (additional phylogenetic signal that emerges only when the data sets interact in a combined analysis). Bayesian posteriors, and a partitioned bootstrap procedure introduced here, indicate strong support for most nodes. The resultant tree implies extensive morphological homoplasy, with many genera emerging as non-monophyletic ( Amphibolurus , Rankinia , Ctenophorus , Physignathus , Diporiphora ). The water and forest dragons ( Physignathus and Hypsilurus ) form a paraphyletic basal assemblage to the more derived Australian forms such as Amphibolurus and Ctenophorus , which include almost all the xeric taxa. However, the thorny devil Moloch horridus is a basal lineage and not closely related to the other arid forms. Tree topology, inferred divergence dates, palaeogeographical and palaeoclimatic data are all consistent with Miocene immigration into Australia from the north by mesic forest ecomorphs, followed by initial diversification in mesic habitats before radiation into xeric habitats facilitated by increasing aridity.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 343–358.     

Karyology of some Brazilian species of Alismataceae

The family Alismataceae ( sensu Cronquist) comprises 11 genera and 75 species of aquatic and semiaquatic herbs. In Brazil, only the two most speciose genera, Echinodorus Rich. ex Engelm. and Sagittaria L., are present. The chromosome number 2 n  = 22 is common to all species. We present karyotypes for eight species, together with their asymmetry index (TF%) and total chromatin length (TCL). All karyotypes have high karyotypic asymmetry and TCL, due to their large and mostly acrocentric chromosomes. The chromosomal evolution of the Alismatidae group is discussed.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 159−164.     

Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals

In theory, parthenogenetic lineages have low evolutionary potential because they inexorably accumulate deleterious mutations and do not generate much genotypic diversity. As a result, most parthenogenetic taxa occupy the terminal nodes of phylogenetic trees. The rate and mode of development of parthenogenesis are important factors to consider when assessing its costs and benefits since they determine both the level of genetic diversity and the ecological adaptability of the resulting lineages. The origin of parthenogenesis is polyphyletic in many taxa, suggesting that genetic systems maintaining sexuality are often labile. In addition, the loss of sex may be achieved in several ways, leading to parthenogenetic lineages with distinct genetic profiles. This could then influence not only the fate of such lineages in the long term, but also the outcome of competition with their sexual counterparts in the short term. In this paper, we review the possible evolutionary routes to parthenogenesis based on a survey of the phylogenetic relationships between sexual and parthenogenetic lineages in a broad range of animals. We also examine the different mechanisms by which parthenogenetic lineages could arise, and discuss the influence of these mechanisms on both the genetic properties and the ecological life styles of the resulting lineages.  © 2003 The Linnean Society of London. Biological Journal of the Linnean Society , 2003, 79 , 151–163.