Karyomorphology of Maianthemum sensu lato (Polygonatae, Ruscaceae)

We report results of karyotype analyses using nine species of Maianthemum from China. The species, except M. atropurpureum (with 2n=72), had 2n=36, and the results support the earlier suggestion that Maianthemum has x=18 with 2n=36 in most species. The species examined, however, showed marked differences in karyotype, particularly in the numbers of metacentric, submetacentric, and acrocentric chromosomes as well as in the number of satellites. In addition, we distinguished three different modes based on the number of clear gaps in chromosome length variation: unimodal, bimodal, and trimodal. The unimodal variation (with no gap) was found in M. dahuricum and M. atropurpureum, the bimodal variation (with one gap) in M. tatsienense, and the trimodal variation (with two gaps) in M. bifolium, M. forrestii, M. japonicum, M. henryi, M. purpureum, and M. lichiangense. In the trimodal variation, the positions of the two gaps may differ from species to species. In addition, the frequency of acrocentric chromosomes per complement was generally higher in the trimodal variation than in the unimodal and bimodal variations. Results of our analyses, which had not been clearly presented prior to this, may provide a better understanding of species evolution in the tribe Polygonatae.     

Phylogeny and temporal diversification of darters (Percidae: Etheostomatinae)

Discussions aimed at resolution of the Tree of Life are most often focused on the interrelationships of major organismal lineages. In this study, we focus on the resolution of some of the most apical branches in the Tree of Life through exploration of the phylogenetic relationships of darters, a species-rich clade of North American freshwater fishes. With a near-complete taxon sampling of close to 250 species, we aim to investigate strategies for efficient multilocus data sampling and the estimation of divergence times using relaxed-clock methods when a clade lacks a fossil record. Our phylogenetic data set comprises a single mitochondrial DNA (mtDNA) gene and two nuclear genes sampled from 245 of the 248 darter species. This dense sampling allows us to determine if a modest amount of nuclear DNA sequence data can resolve relationships among closely related animal species. Darters lack a fossil record to provide age calibration priors in relaxed-clock analyses. Therefore, we use a near-complete species-sampled phylogeny of the perciform clade Centrarchidae, which has a rich fossil record, to assess two distinct strategies of external calibration in relaxed-clock divergence time estimates of darters: using ages inferred from the fossil record and molecular evolutionary rate estimates. Comparison of Bayesian phylogenies inferred from mtDNA and nuclear genes reveals that heterospecific mtDNA is present in approximately 12.5% of all darter species. We identify three patterns of mtDNA introgression in darters: proximal mtDNA transfer, which involves the transfer of mtDNA among extant and sympatric darter species, indeterminate introgression, which involves the transfer of mtDNA from a lineage that cannot be confidently identified because the introgressed haplotypes are not clearly referable to mtDNA haplotypes in any recognized species, and deep introgression, which is characterized by species diversification within a recipient clade subsequent to the transfer of heterospecific mtDNA. The results of our analyses indicate that DNA sequences sampled from single-copy nuclear genes can provide appreciable phylogenetic resolution for closely related animal species. A well-resolved near-complete species-sampled phylogeny of darters was estimated with Bayesian methods using a concatenated mtDNA and nuclear gene data set with all identified heterospecific mtDNA haplotypes treated as missing data. The relaxed-clock analyses resulted in very similar posterior age estimates across the three sampled genes and methods of calibration and therefore offer a viable strategy for estimating divergence times for clades that lack a fossil record. In addition, an informative rank-free clade-based classification of darters that preserves the rich history of nomenclature in the group and provides formal taxonomic communication of darter clades was constructed using the mtDNA and nuclear gene phylogeny. On the whole, the appeal of mtDNA for phylogeny inference among closely related animal species is diminished by the observations of extensive mtDNA introgression and by finding appreciable phylogenetic signal in a modest sampling of nuclear genes in our phylogenetic analyses of darters.     

Phylogenetic and biogeographic diversification of Rhus (Anacardiaceae) in the Northern Hemisphere

Sequences of internal transcribed spacers (ITS) of nuclear ribosomal DNA, the chloroplast ndhF gene, and chloroplast trnL-F regions (trnL intron, and trnL [UAA] 3' exon-trnF [GAA] intergenic spacer) were used for phylogenetic analyses of Rhus, a genus disjunctly distributed in Asia, Europe, Hawaii, North America, and Northern Central America. Both ITS and cpDNA data sets support the monophyly of Rhus. The monophyly of subgenus Rhus was suggested by the combined cpDNA and ITS data, and largely supported in the cpDNA data except that Rhus microphylla of subgenus Lobadium was nested within it. The monophyly of subgenus Lobadium was strongly supported in the ITS data, whereas the cpDNA data revealed two main clades within the subgenus, which formed a trichotomy with the clade of subgenus Rhus plus R. microphylla. The ITS and cpDNA trees differ in the positions of Rhus michauxii, R. microphylla, and Rhus rubifolia, and hybridization may have caused this discordance. Fossil evidence indicates that Rhus dates back to the early Eocene. The penalized likelihood method was used to estimate divergence times, with fossils of Rhus subgenus Lobadium, Pistacia and Toxicodendron used for age constraints. Rhus diverged from its closest relative at 49.1+/-2.1 million years ago (Ma), the split of subgenus Lobadium and subgenus Rhus was at 38.1+/-3.0 Ma. Rhus most likely migrated from North America into Asia via the Bering Land Bridge during the Late Eocene (33.8+/-3.1 Ma). Rhus coriaria from southern Europe and western Asia diverged from its relatives in eastern Asia at 24.4+/-3.2 Ma. The Hawaiian Rhus sandwicensis diverged from the Asian Rhus chinensis at 13.5+/-3.0 Ma. Subgenus Lobadium was inferred to be of North American origin. Taxa of subgenus Lobadium then migrated southward to Central America. Furthermore, we herein make the following three nomenclatural combinations: (1) Searsia leptodictya (Diels) T. S. Yi, A. J. Miller and J. Wen, comb. nov., (2) Searsia pyroides (A. Rich.) T. S. Yi, A. J. Miller and J. Wen, comb. nov., and (3) Searsia undulata (Jacq.) T. S. Yi, A. J. Miller and J. Wen, because our analyses support the segregation of Searsia from Rhus.     

Phylogeny and diversification of bryophytes

The bryophytes comprise three phyla of embryophytes that are well established to occupy the first nodes among extant lineages in the land-plant tree of life. The three bryophyte groups (hornworts, liverworts, mosses) may not form a monophyletic clade, but they share life history features including dominant free-living gametophytes and matrotrophic monosporangiate sporophytes. Because of their unique vegetative and reproductive innovations and their critical position in embryophyte phylogeny, studies of bryophytes are crucial to understanding the evolution of land plant morphology and genomes. This review focuses on phylogenetic relationships within each of the three divisions of bryophytes and relates morphological diversity to new insights about those relationships. Most previous work has been on the mosses, but progress on understanding the phylogeny of hornworts and liverworts is advancing at a rapid pace. Multilocus multigenome studies have been successful at resolving deep relationships within the mosses and liverworts, whereas single-gene analyses have advanced understanding of hornwort evolution.     

Phylogeny and diversification of Valerianaceae (Dipsacales) in the southern Andes

The southern Andean clade of Valeriana provides an excellent model for the study of biogeography. Here we provide new data to help clarify phylogenetic relationships among the South American valerians, with special focus on taxa found in the southern Andes. We found that the southern Andean taxa formed a clade in maximum likelihood and maximum parsimony analyses, and used a Bayesian relaxed clock method to estimate divergence times within Valerianaceae. Our temporal results were similar to other studies, but we found greater variance in our estimates, suggesting that the species of Valeriana have been on the South American continent for some time, and have been successful at exploiting new niche opportunities that reflects the contemporary radiation. Regardless of the time frame for the radiation of the clade, the uptick in the rate of diversification in Valerianaceae appears correlated with a dispersal event from Central to South America. The appearance of Valeriana in the southern Andes (13.7 Ma) corresponds with the transition from closed forest on the western side of the Andes in central Chile to a more open Mediterranean woodland environment. This would suggest that the high species richness of Valerianaceae in South America is the result of multiple, smaller radiations such as the one in the southern Andes, that may or may not be geographically isolated. These smaller radiations may also be driven by species moving into new biomes (migration from a temperate to a more Mediterranean-type climate and into alpine). The degree to which different ecological and geological factors interact to drive diversification is difficult to ascertain. Likewise, without a better-resolved phylogeny it is impossible to determine the directionality of dispersal in this group; did they colonize the southern Andes first, then move northward as the central Andean alpine habitat became more widely available or vice versa?     

Phylogeny,biogeography and ecological diversification of Sarcocornia (Salicornioideae,Amaranthaceae)

Background and Aims Sarcocornia comprises about 28 species of perennial succulent halophytes distributed worldwide, mainly in saline environments of warm-temperate and subtropical regions. The genus is characterized by strongly reduced leaves and flowers, which cause taxonomic difficulties; however, species in the genus show high diversity in growth form, with a mat-forming habit found in coastal salt marshes of all continents. Sarcocornia forms a monophyletic lineage with Salicornia whose species are all annual, yet the relationship between the two genera is poorly understood. This study is aimed at clarifying the phylogenetic relationship between Sarcocornia and Salicornia, interpreting biogeographical and ecological patterns in Sarcocornia, and gaining insights into putative parallel evolution of habit as an adaptation to environmental factors.Methods A comprehensively sampled and dated phylogeny of Sarcocornia is presented based on nuclear ribosomal DNA (external transcribed spacer) and chloroplast DNA (atpB-rbcL, rpl32-trnL) sequences; representative samples of Salicornia were also included in the analyses. To infer biogeographical patterns, an ancestral area reconstruction was conducted.Key Results The Sarcocornia/Salicornia lineage arose during the Mid-Miocene from Eurasian ancestors and diversified into four subclades: the Salicornia clade, the American Sarcocornia clade, the Eurasian Sarcocornia clade and the South African/Australian Sarcocornia clade. Sarcocornia is supported as paraphyletic, with Salicornia nested within Sarcocornia being sister to the American/Eurasian Sarcocornia clade. The American and the South African/Australian Sarcocornia clade as well as the Salicornia clade were reconstructed to be of Eurasian origin. The prostrate, mat-forming habit arose multiple times in Sarcocornia.Conclusions Sarcocornia diversified in salt-laden environments worldwide, repeatedly evolving superficially similar prostrate, mat-forming habits that seem advantageous in stressed environments with prolonged flooding, high tidal movement and frost. Some of these prostrate-habit types might be considered as ecotypes (e.g. S. pacifica or S. pillansii) while others represent good ecospecies (e.g. S. perennis, S. decumbens, S. capensis), hence representing different stages of speciation.     

Molecular phylogeny and biogeographic diversification of Parthenocissus (Vitaceae) disjunct between Asia and North America

? Premise of the study: Parthenocissus is a genus of the grape family Vitaceae and has a disjunct distribution in Asia and North America with members in both tropical and temperate regions. The monophyly of Parthenocissus has not yet been tested, and the species relationships and the evolution of its intercontinental disjunction have not been investigated with extensive sampling and molecular phylogenetic methods. ? Methods: Plastid (trnL-F, rps16, and atpB-rbcL) and nuclear GAI1 sequences of 56 accessions representing all 12 Parthenocissus species were analyzed with parsimony, likelihood, and Bayesian inference. Divergence times of disjunct lineages were estimated with relaxed Bayesian dating. Evolution of the leaflet number was assessed by tracing this character onto Bayesian trees using the Trace Character Over Trees option in the program Mesquite. ? Key results: Parthenocissus is monophyletic and sister to the newly described segregate genus Yua. Two major clades within Parthenocissus are recognizable corresponding to their distribution in Asia and North America. The disjunction between the two continents is estimated to be at 21.64 (95% higher posterior densities 10.23-34.89) million years ago. ? Conclusions: Parthenocissus is likely to have derived from the Eocene boreotropical element. Its current Asian-North American disjunction is dated to the early Miocene, congruent with fossil and paleoclimatic evidence. The tropical species is nested within the temperate clade and is inferred to have dispersed from the adjacent temperate regions. Parthenocissus and Yua are best treated as distinct genera. Leaflet number in this genus has a complex history and cannot be used as a character for infrageneric classification.     

Macroevolutionary patterns in the Aphidini aphids (Hemiptera: Aphididae): diversification, host association, and biogeographic origins

Background

Due to its biogeographic origins and rapid diversification, understanding the tribe Aphidini is key to understanding aphid evolution. Major questions about aphid evolution include origins of host alternation as well as age and patterns of diversification in relation to host plants. To address these questions, we reconstructed the phylogeny of the Aphidini which contains Aphis, the most diverse genus in the family. We used a combined dataset of one nuclear and four mitochondrial DNA regions. A molecular dating approach, calibrated with fossil records, was used to estimate divergence times of these taxa.

Principal Findings

Most generic divergences in Aphidini occurred in the Middle Tertiary, and species-level divergences occurred between the Middle and Late Tertiary. The ancestral state of host use for Aphidini was equivocal with respect to three states: monoecy on trees, heteroecy, and monoecy on grasses. The ancestral state of Rhopalosiphina likely included both heteroecy and monoecy, whereas that of Aphidina was most likely monoecy. The divergence times of aphid lineages at the generic or subgeneric levels are close to those of their primary hosts. The species-level divergences in aphids are consistent with the diversification of the secondary hosts, as a few examples suggest. The biogeographic origin of Aphidini as a whole was equivocal, but the major lineages within Aphidina likely separated into Nearctic, Western Palearctic, and Eastern Palearctic regions.

Conclusions

Most generic divergences in Aphidini occurred in the Middle Tertiary when primary hosts, mainly in the Rosaceae, were diverging, whereas species-level divergences were contemporaneous with diversification of the secondary hosts such as Poaceae in the Middle to Late Tertiary. Our results suggest that evolution of host alternation within Aphidini may have occurred during the Middle Tertiary (Oligocene) when the secondary hosts emerged.     

Phylogeny and diversification patterns among vesicomyid bivalves

Vesicomyid bivalves are among the most abundant and diverse symbiotic taxa in chemosynthetic-based ecosystems: more than 100 different vesicomyid species have been described so far. In the present study, we investigated the phylogenetic positioning of recently described vesicomyid species from the Gulf of Guinea and their western Atlantic and Pacific counterparts using mitochondrial DNA sequence data. The maximum-likelihood (ML) tree provided limited support for the recent taxonomic revision of vesicomyids based on morphological criteria; nevertheless, most of the newly sequenced specimens did not cluster with their morphological conspecifics. Moreover, the observed lack of geographic clustering suggests the occurrence of independent radiations followed by worldwide dispersal. Ancestral character state reconstruction showed a significant correlation between the characters "depth" and "habitat" and the reconstructed ML phylogeny suggesting possible recurrent events of 'stepwise speciation' from shallow to deep waters in different ocean basins. This is consistent with genus or species bathymetric segregation observed from recent taxonomic studies. Altogether, our results highlight the need for ongoing re-evaluation of the morphological characters used to identify vesicomyid bivalves.     

Phylogeny, historical biogeography, and patterns of diversification for Pinus (Pinaceae): phylogenetic tests of fossil-based hypotheses

Pines comprise one of the largest coniferous genera, are distributed throughout the Northern Hemisphere, and have an abundant fossil record. Distributions of fossils have been used to derive a three-step hypothesis of early pine evolution, which postulates a Mesozoic origin for the genus, east-west expansions across Laurasia, and retraction into Eocene refugia. Here, we present phylogenetic tests of this hypothesis using chloroplast sequence data from four loci for 83 pine species. We used the fossil-based hypothesis to derive null expectations concerning monophyly of taxonomic groups, dates of cladogenesis, and patterns of diversification. Phylogenetic analyses using several algorithms subsequently provided rigorous tests of these expectations. Our inferred phylogenies illustrated broad congruence with taxonomic groups, but highlighted consistent problems within subgenus Strobus. Estimated minimum dates of divergence derived from relaxed clock methods were largely consistent with the fossil record and yielded a date for the ingroup node of Pinus of 128+/-4 mya, depending upon the calibration used for subgenus Pinus. Ancestral area reconstructions showed Pinus to have most likely originated in Eurasia. Major clades differed in biogeographic patterns, but were consistent with the fossil-based hypothesis. We found weak support, however, for a change in diversification rate in the Eocene as interpretations of fossil distributions would have predicted.     

Phylogeny of Rhaponticum (Asteraceae, Cardueae-Centaureinae) and related genera inferred from nuclear and chloroplast DNA sequence data: taxonomic and biogeographic implications

BACKGROUND AND AIMS: The precise generic delimitation of the Rhaponticum group is not totally resolved. The lack of knowledge of the relationships between the basal genera of Centaureinae could imply that genera whose position is as yet unresolved could belong to the Rhaponticum group. On the other hand, the affinities among the genera that are considered as members of this group are not well known. The aim of the study is to contribute to the phylogenetic and generic delineation of the Rhaponticum group on the basis of molecular data. METHODS: Parsimony and Bayesian analyses of the combined sequences of one plastid (trnL-trnF) and two nuclear (ITS region and ETS) molecular markers were carried out. The results of these analyses are discussed in the light of the biogeographic history. KEY RESULTS: The Rhaponticum group appears as monophyletic, and closely related to the genus Klasea. The results confirm the preliminary generic delimitation of the Rhaponticum group, with the new incorporation of the genus Centaurothamnus. Ochrocephala is supported as a separate genus from Rhaponticum and, contrary to this, Acroptilon and Leuzea appear as merged into the genus Rhaponticum. Several nomenclatural rearrangements are made in Klasea and Rhaponticum. CONCLUSIONS: The new molecular evidence is consistent with the morphological and karyological data, and suggests particularly coherent biogeographic routes of migration and speciation processes for the genus Rhaponticum. The biogeographic inference proposes a Near East and/or Caucasian origin for the genus. Furthermore, representatives of Rhaponticum could have reached Europe in two different ways: (1) expansion across central Asia to eastern Europe, and (2) expansion through the Near East, North Africa and then to the Iberian Peninsula and the Alps.     

Temporal diversification of Mesoamerican cichlid fishes across a major biogeographic boundary

The Mexican Neovolcanic Plateau sharply divides the vertebrate fauna of Mesoamerica where the climate of both the neotropics and temperate North America gradually blend. Only a few vertebrate groups such as the Heroine cichlids, distributed from South America to the Rio Grande in North America, are found both north and south of the Neovolcanic Plateau. To better understand the geography and temporal diversification of cichlids at this geologic boundary, we used mitochondrial DNA sequences of the cytochrome b (cyt b) gene to reconstruct the relationships of 52 of the approximately 80 species of Heroine cichlids in Mesoamerica. Our analysis suggests several cichlids in South America should be considered as part of the Mesoamerican Heroine clade because they and the cichlids north of the Isthmus of Panama are clearly supported as monophyletic with respect to all other Neotropical cichlids. We also recovered a group containing species in Paratheraps+Paraneetroplus+Vieja as the sister clade to Herichthys. Herichthys is the only cichlid clade north of the Mexican Plateau and it is monophyletic. Non-parametric rate smoothing of cichlid cyt b sequence resulted in an estimated divergence time of approximately 6 million years for Herichthys. This temporal diversification is concordant with divergence times estimated for anurans in the genus Bufo, a group that exhibits a similar geographic distribution. Our results indicate the 5-million-year-old extension of the Mexican Neovolcanic Plateau to the Gulf Coast of Mexico has strongly influenced the current transition between the vertebrate faunas of the Neotropics and Nearctic.     

蜘蛛抱蛋属植物的核型不对称性分析

报道了蜘蛛抱蛋属(Aspidistra)两种植物的染色体数目和核型,其中河口蜘蛛抱蛋(A.hekouensi)的染色体数目(2n=38)为首次报道,四川蜘蛛抱蛋(A.sichuanensis)染色体数目也为2n=38,但其核型与以往的报道有差别.使用染色体内不对称系数(A1)和染色体间不对称系数(A2)对该属34种植物核型的不对称性进行了分析,结果表明该属植物的核型似乎并没有向不对称性增强的方向演化.     

Phylogeny and cryptic diversification in Southeast Asian flying geckos

The closed-canopy forests of Southeast Asia are home to an impressive number of vertebrates that have independently evolved morphologies that enhance directed aerial descent (gliding, parachuting). These assemblages include numerous mammal, frog, snake, and lizard clades. Several genera of gekkonid lizards, in particular, have evolved specialized structures such as cutaneous expansions, flaps, and midbody patagia, that enhance lift generation in the context of unique gliding and parachuting locomotion. The genus Ptychozoon represents arguably the most morphologically extreme, highly specialized clade of gliding geckos. Despite their notoriety and celebrated locomotor ability, members of the genus Ptychozoon have never been the subject of a species-level molecular phylogenetic analysis. In this paper, we utilize molecular sequence data from mitochondrial and nuclear gene fragments to estimate the evolutionary relationships of this unique group of flying geckos. Capitalizing on the recent availability of genetic samples for even the rarest of known species, we include the majority of known taxa and use model-based phylogenetic methods to reconstruct their evolutionary history. Because one species, P. kuhli, exhibits an unusually wide distribution coupled with an impressive range of morphological variation, we additionally use intensive phylogeographic/population genetic sampling, phylogenetic network analyses, and Bayesian species delimitation procedures to evaluate this taxon for the possible presence of cryptic evolutionary lineages. Our results suggest that P. kuhli may consist of between five and nine unrecognized, distinct species. Although we do not elevate these lineages to species status here, our findings suggest that lineage diversity in Ptychozoon is likely dramatically underestimated.     

Phylogeny and biogeography of the genus Illadopsis (Passeriformes: Timaliidae) reveal the complexity of diversification of some African taxa

African jungle babblers or illadopsises, genus Illadopsis Heine, 1859, are small shy babblers which occupy the undergrowth of African humid forest habitats. The taxonomy of Illadopsis as well as its biogeography are currently poorly known because the morphological differentiation is rather subtle and no phylogenetic analysis has been undertaken. To investigate these issues, we sequenced four loci (mitochondrial ND2 and ND3, and nuclear myoglobin intron 2 and β-fibrinogen intron 5) for the seven species of Illadopsis . Our analyses retrieve the monophyly of Illadopsis and suggest that I. albipectus and I. cleaveri , I. puveli and I. rufescens , some individuals of I. rufipennis and I. pyrrhoptera are sister taxa respectively. I. fulvescens appears to be an isolated taxon and our data reveal several cases of "incipient speciation" among its populations. Our dating analyses, using a Bayesian relaxed-clock method, reveal that most splits in Illadopsis occurred synchronously around the Plio-Pleistocene transition, suggesting that some diversification events in African forest taxa took place before the onset of the large-amplitude climatic cycles of the Pleistocene epoch. Thus, the diversification of African taxa in time and space to be more complex than the Pleistocene time frame traditionally associated with the diversification of African forest taxa. Instead we observe a process of differentiation which roughly corresponds to the broadly hypothesised lowland refugia of upper Guinea, eastern and western Guinea-Congolia, although the time frame of this divergence well predates the Pleistocene epoch. Our results also suggest that deep genetic divergences do exist among species complexes of African birds which differ only slightly in morphological characters. As such, molecular analyses are powerful and essential tools if we are to construct the evolutionary history of such lineages in a meaningful manner.     

Phylogeny and biogeography of the Rhinella marina species complex (Amphibia,Bufonidae) revisited: implications for Neotropical diversification hypotheses

Vallinoto, M., Sequeira, F., Sodré, D., Bernardi, J. A. R., Sampaio, I. & Schneider, H. (2009). Phylogeny and biogeography of the Rhinella marina species complex (Amphibia, Bufonidae) revisited: implications for Neotropical diversification hypotheses. —Zoologica Scripta, 39, 128–140. A number of distinct hypotheses have been proposed to account for the origin of the considerable biological diversity found in the Neotropics, which is still a matter of intense debate. Here, we conducted a phylogenetic analysis of the Rhinella marina complex, a group of species widely distributed in Central and South America, combining published data with new sequences of three mtDNA genes (12S, 16S and cyt b) in order to clarify the evolutionary relationships and biogeographical history of the group. We included eight of the ten currently recognized R. marina group species and several outgroups. Maximum parsimony, maximum likelihood, and Bayesian inference analyses produced similar topologies, with two well‐supported main clades, each characterized by a deep subdivision. One of these major clades includes the samples of R. marina from Central America and Ecuador (west of the Andes), whereas the other comprises the remaining species of the group and samples of R. marina from the Amazon basin and other areas east of the Andes. A Bayesian coalescent‐based method (BEAST) dated the divergence between the two major clades, and between the Central American and Ecuadorian clades to the Miocene, matching the timing of other Central‐South American faunal divergences. Taken together, the results highlight the importance of Tertiary events such as the Pebas/marine incursions into the Amazon basin and Andean uplift for the diversification and historical biogeography of R. marina, making such taxa paraphyletic, and provide new perspectives on the debate on its species status.     

Systematics of North American Froelichia (Amaranthaceae subfam. Gomphrenoideae) II: Phylogeny and biogeographic speciation patterns inferred from nrITS sequence data

Molecular phylogenetic analyses of the nuclear ribosomal DNA internal transcribed spacer (ITS 1 and ITS 2) and the 5.8S gene were used to infer a phylogeny among the ten recognized taxa of Froelichia in North America. Analyses using both maximum parsimony (MP) and maximum-likelihood (ML) depicted a low level of sequence divergence though it was sufficient in most cases to differentiate taxa. Froelichia xantusii, a species restricted to southern Baja California was shown to be the basalmost member of the group subtending three clades. Two of the clades received good bootstrap support in the MP analysis and corresponded to a genetically homogeneous F. interrupta, and a clade comprising the two species F. latifolia and F. texana. A third clade receiving low bootstrap support contained F. floridana, F. gracilis, F. arizonica, and F. drummondii. Species diversity within the genus was centered within the Tamaulipan Brushland region of north-east Mexico and the southern portion of the US state of Texas where taxa from two of the three principal clades occurred, indicating a region of high speciation and diversification within the genus.     

Phylogeny of Cerberus (Serpentes: Homalopsinae) and phylogeography of Cerberus rynchops: diversification of a coastal marine snake in Southeast Asia

Aim The biogeography of Southeast Asia has been greatly affected by plate tectonic events over the last 10 Myr and changing sea levels during the Quaternary. We investigated how these events may have influenced the evolution of Cerberus Cuvier, a marine coastal snake belonging to the Homalopsinae (Oriental‐Australian Rear‐fanged Water Snakes). This study is an expansion of a previous study on the biogeography and systematics of Cerberus. Location We obtained species from localities across the range of the widely distributed Cerberus: India, Sri Lanka, the Andaman islands, Myanmar, the Philippines, Borneo, Suluwesi, Sumatra, Vietnam, Thailand, Singapore and Australia. Methods We analysed mtDNA sequences (12S, ND3, ATPase, 2338 nucleotide characters) from 21 localities. The sample consisted of 65 Cerberus rynchops (Schneider), three Cerberus australis (Gray) and four Cerberus microlepis Boulenger. One Homalopsis buccata (Linnaeus), one Bitia hydroides Gray, one Enhydris enhydris (Schneider), and two Enhydris plumbea (Boie) were used as outgroups. Results We produced phylogenetic trees based on parsimony, maximum likelihood and Bayesian analysis. We did not find unambiguous support for the monophly of Cerberus. Cerberus austalis, H. buccata and all other Cerberus populations formed a three‐way basal polytomy under parsimony and C. australis formed the sister group to a clade consisting of H. buccata and all other Cerberus in likelihood and Bayesian analysis. The non‐Australian Cerberus were monophyletic and consisted of four primary biogeographical clades: Indian and Mayanmar, Philippines, Greater Sunda Islands and Suluwesi, and the Thai‐Malay peninsula and Gulf of Thailand. The range of genetic divergence between these clades and Australian Cerberus was 0.06–0.12. Genetic divergence among clades to the west of Australia was less pronounced (Thai‐Malay peninsula and Gulf of Thailand = 0.02–0.05; Sunda Islands and Suluwesi = 0.02–0.05; Philippines = 0.02–0.06; India and Myanmar = 0.04–0.06, Philippines = 0.02–0.5). Main conclusions Gyi [University of Kansas Publications, Museum of Natural History 20 (1970), 47] recognized three species of Cerberus: C. australis (from Australia), C. microlepis (known only from Lake Buhi in the Philippines), and the widely distributed C. rynchops (India to Wallacea). We did not find strong support for the monophyly of the genus. Cerberus australis is highly divergent from all other Cerberus lineages sampled from this region. The geographically widespread C. rynchops is resolved into four biogeographical clades (Indian and Myanmar, Philippines, Greater Sunda Islands and Suluwesi, and the Thai‐Malay Peninsula and Gulf of Thailand). We discuss how the dispersal biology of a salt‐water tolerant, coastal marine taxon and the complex geological history of the region (Tertiary plate tectonic movements and Quaternary sea‐level changes) could produce the observed patterns of diversification.     

Phylogeny and species composition of five European species of Branchiobdella (Annelida: Clitellata: Branchiobdellida) reflect the biogeographic history of three endangered crayfish species

Branchiobdellid annelids are usually found as commensal symbionts associated with crayfish populations, but knowledge of their dispersion and ecology in Europe is generally scarce. We hypothesized that their geographic extension of species and populations may mirror the distribution history of their hosts. We analysed potential host specificities and the geographic distribution of species from the Italian and Austrian Tyrol and Carinthia by characterizing the morphological and genetic features. On the three indigenous crayfish species Astacus astacus, Austropotamobius pallipes and Austropotamobius torrentium , we identified four branchiobdellid species based on morphological characteristics: Branchiobdella hexodonta, Branchiobdella pentodonta, Branchiobdella balcanica and Branchiobdella parasita . In contrast to the morphological classification, phylogenetic analysis using mitochondrial cytochrome c oxidase I (CO-I) sequences identified five main lineages: B. balcanica, B. hexodonta, Branchiobdella italica, B. parasita and B. pentodonta . The arrangement of branchiobdellid species corresponded generally to the geographical distribution of their crayfish hosts' locations but also confirmed previous assumptions of crayfish translocations. Our study provides the first application of ideas on the association of freshwater crayfish and their ectosymbionts to be used for discussing the biogeography of crayfish populations. The phenotypical and genotypical analysis also demonstrated so far ignored effects of human activities at both macro-ecological and micro-ecological levels.