Complex Biogeographic History Research Articles

The phylogeography of the rodent genus Malacomys suggests multiple Afrotropical Pleistocene lowland forest refugia

AbstractAimThis study aims to reconstruct the evolutionary history of the African rodent genus Malacomys and to identify factors driving diversification within this genus.LocationAfrican tropical lowland forest.MethodsAnalyses were based on sampling representatives from most of the known geographical range of the genus. We assessed genetic structure and historical biogeography using a combination of mitochondrial and nuclear markers. Morphological differences between lineages were analysed using a geometric morphometric approach.ResultsThree species of Malacomys are recognized within the genus. Two are endemic to West Africa, and one is endemic to Central Africa. Our analyses reveal a strong phylogeographical structure with 13 lineages, most of them allopatric or parapatric. A complex biogeographical history, including dispersal–vicariance events, explains the current genetic structure of Malacomys. Discrete divergence events within the genus are dated to the mid‐Pliocene (3.7 Ma, 95% range: 2.4–5.2 Ma) and the Pleistocene (less than 1.9 Ma, with most events less than 1 Ma). Morphological variation is partly congruent with genetic structure and may indicate local adaptations.Main conclusionsClimatic oscillations, which led to periodic fragmentation of the forest habitat, seem to be the major driver of diversification within this genus. Our results support the existence of multiple small, rather than a few large, forest refugia during glacial maxima. Rivers have played a significant role in shaping boundaries of several regional haplogroups, either by promoting diversification or by preventing secondary contact between previously isolated lineages.

The New World oil‐collecting bees Centris and Epicharis (Hymenoptera, Apidae): molecular phylogeny and biogeographic history

We present a first comprehensive time‐calibrated phylogeny for two Neotropical genera of bees, Centris and Epicharis, whose females collect floral oil together with pollen for larval provisioning, and that traditionally have been grouped in the tribe Centridini. Our analyses rely on a matrix of 167 taxa and 4228 aligned nucleotides for the subfamily Apinae, with denser sample of Centris and Epicharis. Centris and Epicharis are strongly supported monophyletic groups, but Centridini is paraphyletic in relation to the corbiculate bees. The inner phylogenetic relationships of Epicharis agree with the current taxonomic classification. In Centris, three main clades were recovered, namely the Centris, Trachina and Melacentris groups. Inner relationships in Centris suggest the reinstatement of some subgenera and proposition of new ones. Early diversification of Centris and Epicharis took place at the tropical regions of South America. Epicharis and the Melacentris group in Centris mostly diversified in that region, expanding over Central America and tropical North America only recently in the last 3 My. The groups Trachina and Centris present a complex biogeographic history, with expansions to the Nearctic region, the Antilles, and temperate regions of South America in the late Oligocene and Miocene.

A data-driven method for selecting candidate reference sites for stream bioassessment programs using generalised dissimilarity models

Key issues with defining reference condition for stream bioassessment are (1) equivocal definitions of ‘minimally disturbed’ pressure criteria and wide-ranging approaches to site selection, (2) highly modified regions where near-pristine areas do not exist, leading to management decisions based on inconsistent and unquantified benchmarks and (3) costly field campaigns associated with ‘extensive spatial survey’ approaches. We used generalised dissimilarity modelling (GDM) to classify stream segments into ecotypes, and transparently and efficiently define candidate reference conditions for the Ecosystem Health Monitoring Program (EHMP) assessment area in south-eastern Queensland, a highly modified region with a complex biogeographic history. We modelled fish presence–absence data from 396 sites with GIS-based natural and anthropogenic predictors. Stream segments were classified into ecotypes using the GDM-transformed natural variables so that (1) reference-site selection adequately covered the β-diversity of the study area and (2) we could evaluate the validity of incorporating sites from neighbouring catchments outside of the EHMP assessment area. Relationships between selected anthropogenic variables (the river disturbance index and %stream connectivity) and fish assemblages were used to define pressure criteria and map candidate reference conditions. We conclude by describing a new framework that can be used to select indicator-specific reference sites by GDM and a stratified, probabilistic sampling design.

Biodiversity in the Mexican highlands and the interaction of geology, geography and climate within the Trans‐Mexican Volcanic Belt

AbstractAim(1) To synthesize data on the physical and phylogeographical history of the Mexican highlands, with a focus on the Trans‐Mexican Volcanic Belt (TMVB), and (2) to propose approaches and analyses needed for examining the interaction of climate and volcanism.LocationMexico.MethodsWe performed a literature and data survey of the climatic, geological and phylogeographical history of the Mexican highlands. We then assessed how the expected effects of topographic isolation, co‐occurring palaeoclimatic fluctuations and volcanism can be tested against the distribution of genetic diversity of high‐elevation taxa.ResultsThe Mexican highlands present a complex biogeographical, climatic and geological history. Montane taxa have been exposed to a sky‐island dynamic through climate fluctuations, allowing for long‐term in situ population persistence, while also promoting recent divergence and speciation events. Volcanic activity transformed part of the Mexican highlands during the Pleistocene, mainly in the TMVB, leading to co‐occurring climate and topographical changes. The TMVB highlands provide a suitable template to examine how low‐latitude mountains can facilitate both the long‐term persistence of biodiversity as well as allopatric and parapatric speciation driven by climatic and geological events.Main conclusionsClimate fluctuations, together with recent volcanism, have driven the diversification and local persistence of biodiversity within the Mexican highlands. The climate–volcanism interaction is challenging to study; however, this can be overcome by coupling genomic data with landscape analyses that integrate the geological and climatic history of the region.

Who’s getting around? Assessing species diversity and phylogeography in the widely distributed lichen-forming fungal genus Montanelia (Parmeliaceae, Ascomycota)

Brown parmelioid lichens comprise a number of distinct genera in one of the most species-rich families of lichen-forming fungi, Parmeliaceae (Ascomycota). In spite of their superficial similarity, a number of studies of brown parmelioids have provided important insight into diversification in lichen-forming fungi with cosmopolitan distributions. In this study we assess species diversity, biogeography and diversification of the genus Montanelia, which includes alpine to temperate saxicolous species. We sampled each of the five known species, four of which are known from broad, intercontinental distributions. In order to identify potential biogeographical patterns, each broadly distributed species was represented by individuals collected across their intercontinental distributions. Molecular sequence data were generated for six loci, including three nuclear protein-coding markers (MCM7, RPB1, and RPB2), two nuclear ribosomal markers (ITS and nrLSU), and a fragment of the mitochondrial small subunit. We used three sequence-based species delimitations methods to validate traditional, phenotype-based species and circumscribe previously unrecognized species-level lineages in Montanelia. Relationships among putative lineages and divergence times were estimated within a coalescent-based multi-locus species tree framework. Based on the results of the species delimitation analyses, we propose that the genus Montanelia is likely comprised of six to nine species-level lineages, including previously unrecognized species-level diversity in the nominal taxa M. panniformis and M. tominii. In contrast, molecular sequence data suggest that M. predisjuncta may be conspecific with the widespread taxon M. disjuncta in spite of distinct morphological differences. The rate-based age estimation of the most recent common ancestor of Montanelia (ca. 23.1Ma) was similar to previous estimates based on the fossil record. Furthermore, our data suggest that diversification in Montanelia occurred largely during the Neogene. At least three Montanelia species are broadly distributed throughout Asia, Europe, and North America with no evidence of phylogeographic substructure. In contrast to broadly distributed Montanelia species, our study suggests Pleistocene-dominated diversification and complex biogeographic history in the M. tominii group. Our analyses provide additional insight for understanding diversification and uncovering cryptic diversity in cosmopolitan species of lichen-forming fungi.

Halfway encounters: Meeting points of colonization routes among the southern beeches Nothofagus pumilio and N. antarctica

The Patagonian region is characterized by a complex biogeographic history, with evidence of deep phylogeographic breaks shared among species. Of particular interest to conservation is the nature of colonization and settlement patterns after the last glacial period, including the detection of secondary contact between different lineages and/or hybridization among related species around phylogeographic breaks. Here we studied population demography and past hybridization of two widespread tree species endemic to South America, Nothofagus pumilio and N. antarctica.Using 8 nuclear microsatellites we genotyped 41 populations of both species. Genetic variation and structure across the geographic region were evaluated within and among species and the past demographic history of hybridization between the two species was inferred using Approximate Bayesian Computation (ABC).Northern and southern lineages were identified in each species, and Bayesian clustering revealed their convergence at mid latitudes (42°S). Spatial genetic structure (SGS) also indicated the existence of a genetic discontinuity at these latitudes, which is in agreement with previous data from maternal DNA markers. Several populations around 42–44°S presented high levels of genetic diversity with a decrease toward southern populations. Even though the species are clearly differentiated (G’ST=0.335), admixed gene pools were observed in both species. Two independent runs of ABC suggested that inter species admixture-like patterns occurred within the timescale of the Last Glacial Maximum (around 20,000 BP). We also provide evidences of recent and bi-directional hybridization/introgression between the two Nothofagus species and describe features of the populationś demography in the past. The settlement of a secondary contact zone in Nothofagus species around 42–44°S coincides with the phylogeographic breaks and hotspots of genetic diversity found in other plant and animal species in Patagonia, highlighting its importance as reservoir of diversity. The characterization of the population history of native species can contribute substantially to long-term conservation and management policies.

Multilocus phylogeny and taxonomic revision of the Hemidactylus robustus species group (Reptilia, Gekkonidae) with descriptions of three new species from Yemen and Ethiopia

The gecko genus Hemidactylus, with its 132 currently recognized species, ranks among the most species-rich reptile genera. Recent phylogenetic studies disclosed unexpectedly high genetic variability and complex biogeographic history within its arid clade distributed in the Mediterranean, Northeast Africa, Middle East and the Indian subcontinent. Particularly, the species from the Arabian Peninsula have been lately the subject of many taxonomic revisions that have resulted in the descriptions of 16 new taxa. Yet not all detected cryptic lineages have been treated taxonomically and thoroughly investigated morphologically. Based on phylogenetic analyses of two mtDNA (12S, cytb) and four nDNA (cmos, mc1r, rag1, rag2) gene fragments of a total length of 4015 bp in combination with analysis of morphological characters, we reinvestigate the systematics of the H. robustus species group consisting of the widespread H. robustus and three undescribed species, two of which occur in Southwest Yemen and one in central Ethiopia. By comparing two phylogenetic inference methods, concatenated gene trees and species-tree estimation, we reconstruct the phylogeny of the H. robustus species group. The coalescent-based species-tree estimation resulted in different tree topology than the concatenation approach, being probably a result of incomplete lineage sorting of ancestral polymorphism, suggesting that the H. robustus species group is in a stage of incipient speciation. The degree of differentiation of the characters examined within the H. robustus species group allowed us to provide a redescription of H. robustus and formally describe three new species of Hemidactylus – H. adensis sp. nov. and H. mandebensis sp. nov. from Yemen and H. awashensis sp. nov. from Ethiopia.

Out of Africa: did Emys orbicularis occidentalis cross the Strait of Gibraltar twice?

The narrow Strait of Gibraltar has separated the African and European continents since the Miocene (5.3 Mya), with a different degree of permeability for Mediterranean taxa. Southern and northern regions of the Iberian Peninsula and Morocco, respectively, are key areas to evaluate the colonization dynamics and biogeographic history of taxa occurring at both sides of this strait. The Ibero-Maghrebian subspecies of the European pond turtle,Emys orbicularis occidentalis, is patchily distributed and threatened throughout most of the Iberian Peninsula and northern Morocco and its origin is thought to be in North Africa. Here we expand the geographic sampling across the Iberian Peninsula and Morocco, with special emphasis in the southern tip of the peninsula and northern Morocco, and analyze mtDNA sequences of 183E. o. occidentalisto better understand the complex biogeographic history of this subspecies. We provide for the first time evidence for shared haplotypes of Iberian and North African pond turtles, with an additional haplotype in the southern Iberian Peninsula derived from Moroccan haplotypes. This supports the hypothesis that the Strait of Gibraltar constitutes no significant biogeographic barrier forE. orbicularis. However, the newly discovered shared, or extremely similar, haplotypes of European pond turtles from the southern Iberian Peninsula and Morocco suggest either that at least two independent natural colonization waves from Morocco have reached the Iberian Peninsula or that Moroccan turtles were accidentally or deliberately introduced there.

Phylogenetic relationships and character evolution in Heuchera (Saxifragaceae) on the basis of multiple nuclear loci.

• The use of multiple genetic regions from the nuclear genome, including low-copy markers, has long been recognized as essential to robust phylogenetic construction, addressing gene tree incongruence, and allowing increased resolution to test current taxonomy and resolve basic hypotheses about character evolution, biogeography, and other organismal traits of interest to biologists. Heuchera, the largest genus of Saxifragaceae endemic to North America, has presented an unusually difficult case for systematists with limited sampling in previous molecular studies. We used morphological and multilocus molecular phylogenetic data to test the monophyly of Heuchera, better resolve hypotheses of relationships, and test hypotheses of character evolution, biogeography, and diversification rates.• Phylogenetic relationships were inferred using sequences from six nuclear loci and 39 morphological characters using concatenation and coalescent analysis. Ancestral state reconstruction, diversification, and correlated evolution of morphological traits were performed using parsimony, BiSSE, and Pagel's method, respectively.• The concatenation and species tree analyses gave confident support to the monophyly of Heuchera and suggested several well-supported subclades. The addition of morphological data significantly improved support numbers. Ancestral character reconstruction suggested frequent homoplasy and reversal of floral characters and a complex biogeographical history.• Heuchera is a natural genus; however, the current subgeneric classification is artificial and requires revision. Biogeographic reconstructions suggest a Pacific Northwest origin for the genus; morphological shifts in stamen exsertion and hypanthium length are hypothesized to have driven diversification in Heuchera in concert with possible pollinator shifts.

New Species and Records of Chihuahuan Desert Springsnails, With a New Combination forTryonia brunei

This is the last in a series of papers clarifying the taxonomy of a critically imperiled assemblage of cochliopid gastropods (Tryonia sensu lato) that inhibit thermal springs in the Chihuahuan Desert (Mexico and United States). We describe 2 new narrowly endemic species of Tryonia from Chihuahua, both of which appear to have been recently extirpated, and we provide new records for 4 congeners (also from Chihuahua) and for a species of Pseudotryonia (from Durango). The 2 new species of Tryonia differ from closely similar regional congeners in shell and penial characters. On the basis of new anatomical data, we also transfer T. brunei Taylor, 1987 to the genus Juturnia and provide evidence that this species, which was endemic to the Phantom Lake spring complex in west Texas, became extinct sometime after 1984. Our findings provide additional insight into the complex biogeographic history of the Chihuahuan Desert cochliopids and further document the recent decline of regional spring-dwelling biota as a result of groundwater mining.

Diversification of almonds, peaches, plums and cherries – Molecular systematics and biogeographic history of Prunus (Rosaceae)

Most previous molecular phylogenetic studies of Prunus have been conducted primarily with crop species and their close relatives. As the center of crop diversity of the genus is in Eurasia, the geographic origin of Prunus has inevitably been inferred to be Eurasia as well. The lesser-known tropical Prunus species have not been well represented in previous phylogenetic reconstructions; therefore, their effects on inferences about the phylogenetic structure and geographic origin of Prunus are uncertain. In this study, we examined the phylogeny of Prunus, including an expanded sampling of species from tropical regions in Southeast Asia and the Americas, using sequences from four plastid markers and the nuclear ribosomal ITS region. A penalized likelihood method was used to estimate the absolute age of Prunus and the timing of infrageneric cladogenic events. The geographic origin of Prunus and ancestral sites of cladogenesis were inferred using the Bayes-DIVA approach. Our results indicate that the modern genus appeared ∼61Myr in eastern Asia and that diversification of all major lineages may have been triggered by the global warming period of the early Eocene. In addition, our molecular dating estimates suggest that the crown clade that includes the temperate deciduous crop species is older than the one that includes the tropical evergreen species, while incongruence between plastid and nuclear phylogenies suggests that the latter lineage originated via an ancient hybridization event. The most recent common ancestor (MRCA) of the temperate crop species was a component of the continuous boreotropical forests of the Northern Hemisphere, while the MRCA of the tropical species represented the last remains of the boreotropical elements and subsequently radiated throughout the Old and New World tropics from refugial areas at lower latitudes. Complex biogeographic histories leading to the present global distribution of the genus were driven by several geologic events, climatic oscillations, and independent dispersals across continents via the Bering and the North Atlantic Land Bridges during different geologic time periods.

Molecular dating of Winteraceae reveals a complex biogeographical history involving both ancient Gondwanan vicariance and long‐distance dispersal

AbstractAimOur aim was to implement a molecular dating analysis and assess divergence times among taxa of Winteraceae. This enabled us to test hypotheses of vicariance versus long‐distance dispersal to explain intercontinental disjunctions in the family.LocationMadagascar, Australia (including Lord Howe Island), New Zealand, New Caledonia and South America.MethodsWe sampled all Australian species and subspecies of Winteraceae. We also included the monotypic Takhtajania perrieri and at least two species of each genus from New Zealand, New Caledonia and South America. Three sets of sequences were combined into one data matrix, including two internal transcribed spacer (ITS) data sets and a trnL–F data set. Both ITS data sets included all genera of Winteraceae, and the paralogous genes identified in Zygogynum s.l. in a previous study were sequenced and aligned in separate ITS data sets. A Bayesian molecular phylogenetic tree of extant Winteraceae was used as a backbone constraint in paup* to establish the placement of fossils. Bayesian analyses were performed using beast, implementing fossil priors to fit lognormal distributions, to test a maximum‐parsimony phylogeny and assess divergence times.ResultsInterspecific relationships generally agreed with previous analyses. In particular, Bubbia comptonii was found to be sister to the rest of the Bubbia/Zygogynum clade, but our analysis has uniquely found sister clades within this group: one from New Caledonia, and one from Australia including Lord Howe Island. The phylogeny yields an age of 91.2 Ma with a 95% confidence interval of 118–67 Ma for crown‐group Winteraceae.Main conclusionsThe estimated age of Takhtajania is consistent with its origin in Madagascar as a result of Gondwanan vicariance – the only angiosperm for which this has been demonstrated with confidence. Differentiation of the rest of this ancient clade is a complicated story of vicariance as a result of the rifting, submergence and exhumation of continents and of long‐distance dispersal and extinctions.

Molecular phylogenetics ofVandaand related genera (Orchidaceae)

The genus Vanda and its affiliated taxa are a diverse group of horticulturally important species of orchids occurring mainly in South-East Asia, for which generic limits are poorly defined. Here, we present a molecular study using sequence data from three plastid DNA regions. It is shown that Vanda s.l. forms a clade containing approximately 73 species, including the previously accepted genera Ascocentrum, Euanthe, Christensonia, Neofinetia and Trudelia, and the species Aerides flabellata. Resolution of the phylogenetic relationships of species in Vanda s.l. is relatively poor, but existing morphological classifications for Vanda are incongruent with the results produced. Some novel species relationships are revealed, and a new morphological sectional classification is proposed based on support for these groupings and corresponding morphological characters shared by taxa and their geographical distributions. The putative occurrence of multiple pollination syndromes in this group of taxa, combined with complex biogeographical history of the South-East Asian region, is discussed in the context of these results.(c) 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 173, 549-572.

Molecular Phylogenetic Analysis of the Circumboreal Genus Cassiope (Ericaceae) Reveals Trends in Some Morphological and Wood Anatomy Characters and Likely Reticulate Evolution

The genus Cassiope is comprised of 17 species of dwarf alpine shrubs that exhibit a variety of leaf morphologies, yet have very similar flowers and habits. The genus is circumboreally distributed, with species diversity concentrated in northwestern North America and in eastern Asia. This clade has been previously shown to be strongly supported as sister to the subfamily Ericoideae, but relationships within the genus have never been the subject of any phylogenetic study. The goal of this study was to use three molecular markers from the chloroplast and nuclear genomes to generate a phylogeny of Cassiope. Our initial analyses suggested that three species negatively impacted phylogeny reconstruction by introducing conflict between the nuclear and chloroplast genomes. Reanalysis with those three taxa removed generated a very strongly supported phylogeny, suggesting that these three taxa may be of hybrid origin. Some evolutionary trends in morphology and anatomy are apparent based upon analyses using the restricted taxon sampling. Characters with discrete character states, such as leaf form and stomatal distribution, are tightly correlated but appear to be homoplasious within the genus. Continuously varying characters such as habitat elevation and aspects of wood anatomy show compelling phylogenetic trends that may be related to the fact that these species evolved in alpine and subalpine habitats. Cassiope appears to have a complex biogeographical history in the northern hemisphere, which cannot be completely resolved with the current dataset. However, it is likely that the genus has undergone multiple speciation events in the Himalayas with one or more dispersals into northwestern North America, or alternately with origins in the American Northwest followed by dispersal and subsequent divergence in the Himalayas.

Populations at risk: conservation genetics of kangaroo mice (Microdipodops) of the Great Basin Desert.

The Great Basin Desert of western North America has experienced frequent habitat alterations due to a complex biogeographic history and recent anthropogenic impacts, with the more recent alterations likely resulting in the decline of native fauna and flora. Dark (Microdipodops megacephalus) and pallid (M. pallidus) kangaroo mice are ecological specialists found within the Great Basin Desert and are potentially ideal organisms for assessing ecosystem health and inferring the biogeographic history of this vulnerable region. Herein, newly acquired nuclear-encoded microsatellite loci were utilized to assess patterns of variation within and among spatially discrete groups of kangaroo mice and to evaluate gene flow, demographic trends, and genetic integrity. Results confirm that there are at least three genetically distinct units within M. megacephalus and two such units within M. pallidus. The three units of M. megacephalus appear to have different demographic histories, with effectively no gene flow among them since their divergence. Similarly, the two units of M. pallidus also appear to have experienced different demographic histories, with effectively no gene exchange. Contemporary effective population sizes of all groups within Microdipodops appear to be low (<500), suggesting that each genetic lineage may have difficulty coping with changing environmental pressures and hence may be at risk of extirpation. Results of this study indicate that each Microdipodops group should be recognized, and therefore managed, as a separate unit in an effort to conserve these highly specialized taxa that contribute to the diversity of the Great Basin Desert ecosystem.The Great Basin Desert of western North America has experienced frequent habitat alterations due to a complex biogeographic history and recent anthropogenic impacts, with the more recent alterations likely resulting in the decline of native fauna and flora. Herein, newly acquired nuclear-encoded microsatellite loci were utilized to assess patterns of variation within and among spatially discrete groups of the dark (Microdipodops megacephalus) and pallid (M. pallidus) kangaroo mouse, and to evaluate gene flow, demographic trends, and genetic integrity. Results of this study indicate that each Microdipodops group should be recognized, and therefore managed, as a separate unit in an effort to conserve these highly specialized taxa that contribute to the diversity of the Great Basin Desert ecosystem (photo credit J. C. Hafner).

Out of Arabia: A Complex Biogeographic History of Multiple Vicariance and Dispersal Events in the Gecko Genus Hemidactylus (Reptilia: Gekkonidae)

The geological history of the Arabian Peninsula has played a crucial role in shaping current diversity and distribution patterns of many Arabian and African faunal elements. The gecko genus Hemidactylus is not an exception. In this study, we provide an insight into the phylogeny and systematics of 45 recognized species of the so-called Arid clade of the genus Hemidactylus from Arabia, the Horn of Africa, the Levant and Iran. The material comprises 358 specimens sequenced for up to two mitochondrial (12S rRNA, cytochrome b) and four nuclear (mc1r, cmos, rag1, rag2) genes with 4766 bp of the concatenated alignment length. A robust calibrated phylogeny and reconstruction of historical biogeography are inferred. We link the history of this genus with major geological events that occurred in the region within the last 30 million years. Two basal divergences correspond with the break-ups of the Arabian and African landmasses and subsequent separation of Socotra from the Arabian mainland, respectively, segregating the genus by means of vicariance. Formation of the Red Sea led to isolation and subsequent radiation in the Arabian Peninsula, which was followed by multiple independent expansions: 13.1 Ma to Iran; 9.8 Ma to NE Africa; 8.2 to Socotra Archipelago; 7–7.3 Ma two colonizations to the Near East; 5.9 Ma to NE Africa; and 4.1 to Socotra. Moreover, using multiple genetic markers we detected cryptic diversity within the genus, particularly in south-western Arabia and the Ethiopian highlands, and confirmed the existence of at least seven new species in the area. These findings highlight the role of Arabia and the Horn of Africa as an important Hemidactylus diversity hotspot.

Phylogeny of the dragonfly genus Sympetrum (Odonata: Libellulidae)

The libellulid dragonfly genus Sympetrum has been recognized since 1833, but lacks any morphological synapomorphies to unite the taxon. Previous researchers have disagreed over which species belong in Sympetrum, bringing the monophyly of the genus into question. We use DNA sequence data from 6 genetic loci (16S, tRNA-valine, 12S, elongation factor 1 alpha, cytochrome oxidase subunit I, and the second internal transcribed spacer region) and 25 morphological characters (mainly genitalic) to test the monophyly of Sympetrum with Bayesian inference and maximum likelihood analyses. Under Bayesian inference, all Sympetrum species included in this study form a clade, which also contains the Hawaiian monotypic genus Nesogonia, often considered a close relative of Sympetrum. Phylogenetic analyses also reveal at least six strongly supported clades (treated as species groups) within Sympetrum, but relationships between these species groups remain unresolved or unsupported. Although the relationships between Sympetrum species groups remain unresolved, several species groups include taxa from multiple biogeographic regions/continents, and the species group sister to the rest of Sympetrum contains migratory species from the New World and Africa. This pattern suggests a complex biogeographic history in Sympetrum shaped by vicariance and dispersal. Preliminary estimates of the divergence dates of Sympetrum species groups outline a rapid radiation of the groups approximately 32-38 million years ago, possibly influenced by cooling and drying climates of the late Eocene and early Oligocene.

Phylogenetic relationships ofNecrosuchus ionensisSimpson, 1937 and the early history of caimanines

Cranial fragments associated with the holotype of Necrosuchus ionensis reveal a dorsally shifted foramen aereum on the quadrate and a long, slender descending process of the exoccipital lateral to the basioccipital and approaching the basioccipital tubera. The former suggests that Necrosuchus is an alligatoroid and not a crocodylid, as first suggested; and the latter that it is a caiman. The scapulocoracoid shows evidence of early closure of the synchondrosis, further supporting a caiman affinity. Although we cannot yet pinpoint the phylogenetic placement of Necrosuchus amongst caimans, it nevertheless establishes a caimanine presence in South America by the Early Palaeocene. A review of other Palaeocene–Eocene caimans reveals a complex biogeographical history suggesting multiple dispersal events between North and South America, even if the modern caiman assemblage is monophyletic. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163, S228–S256.

Biogeography and Mass Extinction: Extirpation and re-invasion of Normalograptus species (Graptolithina) in the Late Ordovician Palaeotropics

SUMMARY Normalograptids constitute a distinctive but not easily identified group of derived axonophorans. A new study of Normalograptus morphology indicates that many Late Ordovician taxa previously identified as Normalograptus are actually referable to Styracograptus and related climacograptoids. These re-identifications have led to the recognition of a complex biogeographic history among normalograptids and their descendants, including an interesting pattern that had previously been overlooked – a late Katian disappearance of Normalograptus from the palaeotropics. Normalograptid palaeogeographic distribution in the Ordovician appears to comprise 5 main phases: (1) evolutionary origin probably in relatively high palaeolatitudes in the early to mid Darriwilian; (2) spread to global distribution in later Darriwilian time; (3) retreat from most low palaeolatitude regions during the early Katian, with perhaps a slightly delayed retreat from Laurentia; (4) a complete extirpation from the low palaeolatitudes by the mid Katian (Ea4); (5) reinvasion of the low palaeolatitudes that accompanies the remarkable ecological and evolutionary replacement of the Diplograptina by species of Normalograptus and their descendants during the latest Katian–early Hirnantian. We propose two sets of hypotheses to explain Late Ordovician Normalograptus distribution. First, given the low species diversity of Normalograptus , we suggest as a null hypothesis that the disappearance of normalograptids from low palaeolatitudes during the late Sandbian and early Katian as simply a stochastic outcome – a small clade simply went extinct by chance alone. The alternative is that the loss of Normalograptus species reflects some form of extinction for cause, either: (1) competitive exclusion; or (2) an inability to adapt to changing environmental conditions. In the case of the competitive exclusion hypothesis, the most likely competitors are species of the Diplograptina.

Opening a box of cryptic taxa - the first review of the North African desert lizards in the Trapelus mutabilis Merrem, 1820 complex (Squamata: Agamidae) with descriptions of new taxa

We present a review of the morphology and current taxonomy of North African Trapelus species. The Saharo-Sindian agamid genus contains 15 species, of which five occur in northern Africa. The taxonomy of this complex group continues to provide difficulties for taxonomists because of a lack of consistent morphologically diagnostic characters and relatively high intraspecific morphological variation. In particular, the widespread species Trapelus mutabilis, which occurs from Egypt in the east to Mauritania in the west, has been identified as a species complex and probably represents an artificial grouping of unrelated taxa. This taxonomic uncertainty is exacerbated because a type specimen for T. mutabilis was never designated. In our taxonomic review, we designate a neotype for T. mutabilis, allowing a review of the northern African species, the description of two new taxa, and the compilation of a comprehensive identification key. We present a multivariate analysis of morphology within T. mutabilis and, in addition, we present a molecular phylogenetic analysis incorporating a ∼500-bp region of the mitochondrial 16S ribosomal RNA gene, and a relaxed molecular clock analysis to estimate the ages of clades within Trapelus. Our results demonstrate that these lineages have a deep and complex biogeographical history.