Poor Dispersal Capabilities Research Articles

Genomic patterns in the dwarf kingfishers of northern Melanesia reveal a mechanistic framework explaining the paradox of the great speciators

Abstract The paradox of the great speciators describes a contradictory biogeographic pattern exhibited by numerous avian lineages in Oceania. Specifically, these lineages display broad geographic distributions across the region, implying strong over-water dispersal capabilities; yet, they also display repeated genetic and phenotypic divergence—even between geographically proximate islands—implying poor inter-island dispersal capabilities. One group originally cited as evidence for this paradox is the dwarf kingfishers of the genus Ceyx. Here, using genomic sequencing and comprehensive geographic sampling of the monophyletic Ceyx radiation from northern Melanesia, we find repeated, deep genetic divergence and no evidence for gene flow between lineages found on geographically proximate islands, providing an exceptionally clear example of the paradox of the great speciators. A dated phylogenetic reconstruction suggests a significant burst of diversification occurred rapidly after reaching northern Melanesia, between 3.9 and 2.9 MYA. This pattern supports a shift in net diversification rate, concordant with the expectations of the “colonization cycle” hypothesis, which implies a historical shift in dispersiveness among great speciator lineages during the evolutionary past. Here, we present a formalized framework that explains how repeated founder effects and shifting selection pressures on highly dispersive genotypes are the only ultimate causes needed to generate the paradox of the great speciators. Within this framework, we emphasize that lineage-specific traits and island-specific abiotic factors will result in varying levels of selection pressure against dispersiveness, caused by varying proximate eco-evolutionary mechanisms. Overall, we highlight how understanding patterns of diversification in the Ceyx dwarf kingfishers helped us generate a cohesive framework that provides a rigorous mechanistic explanation for patterns concordant with the paradox of the great speciators and the repeated emergence of geographic radiations in island archipelagoes across the globe.

Cryptic diversity and phylogeographic patterns of Deto echinata (Isopoda: Detonidae) in southern Africa

Recent phylogeographic studies of poorly-dispersing coastal invertebrates in highly biodiverse regions have led to the discovery of high levels of cryptic diversity and complex phylogeographic patterns that suggest isolation, geological, and ecological processes have shaped their biodiversity. Studies of southern African coastal invertebrates have uncovered cryptic diversity for various taxa and phylogeographic patterns that, although sharing some similarities across taxa, do differ. These findings underscore the need for additional studies to better understand the biodiversity levels, distributional patterns, and processes responsible for producing coastal biodiversity in that region. The coastal isopod Deto echinata is of particular interest, as its complex taxonomic history, poor dispersal capabilities, and broad geographic distribution suggest the potential for cryptic diversity. We use mitochondrial and nuclear sequences to characterize D. echinata individuals from localities ranging from northern Namibia to Glentana, about 2,500 km along the coastline on the south coast of South Africa. These are used to assess whether D. echinata harbors cryptic genetic diversity and whether phylogeographic distributional patterns correlate with those previously documented for other coastal isopods in the region. Analysis of mitochondrial and nuclear sequences revealed two deeply-divergent lineages that exhibit a distributional break in the Cape Peninsula region. These findings suggest D. echinata is a cryptic species complex in need of taxonomic revision and highlight the need for further taxonomic and phylogeographic studies of similarly poorly-dispersing coastal invertebrates in southern Africa.

Phylogeography of two codistributed terrestrial snails in the Maputaland–Pondoland–Albany biodiversity hotspot, South Africa

Abstract We investigated the evolutionary patterns of two forest-dwelling endemic terrestrial snails (Gittenedouardia spadicea and Maizania wahlbergi) in the Maputaland–Pondoland–Albany biodiversity hotspot in South Africa to examine the degree of phylogeographical congruence between the two species. Phylogenetic relationships and divergence time estimations within each species were inferred using the combined mitochondrial DNA (mtDNA) sequence dataset for the cytochrome c oxidase subunit I (COI) and large subunit ribosomal RNA (16S rRNA). In addition, the rapidly evolving COI datasets were used to infer intraspecific genetic structure and population differentiation within both species. Phylogeographical concordance factor (PCF) analysis was used to statistically estimate the degree of congruence between the two species at localities where both species were sampled. Phylogenetically, G. spadicea exhibited two clades that diverged during the Plio/Pleistocene, while M. wahlbergi formed a single shallow clade that showed Pleistocene divergence. The haplotype networks for the COI locus demonstrated evidence of geographical and genetic isolation within both species. PCF analysis demonstrated partial phylogeographical concordance, suggesting that the two species may have been affected by similar ancient climatic events. Traits other than poor dispersal capabilities and limited gene flow may also influence how a species responds to fluctuating climate change.

Climatic stability, not average habitat temperature, determines thermal tolerance of subterranean beetles

The climatic variability hypothesis predicts the evolution of species with wide thermal tolerance ranges in environments with variable temperatures, and the evolution of thermal specialists in thermally stable environments. In caves, the extent of spatial and temporal thermal variability experienced by taxa decreases with their degree of specialization to deep subterranean habitats. We use phylogenetic generalized least squares to model the relationship among thermal tolerance (upper lethal limits), subterranean specialization (estimated using ecomorphological traits), and habitat temperature in 16 beetle species of the tribe Leptodirini (Leiodidae). We found a significant, negative relationship between thermal tolerance and the degree of subterranean specialization. Conversely, habitat temperature had only a marginal effect on lethal limits. In agreement with the climatic variability hypothesis and under a climate change context, we show that the specialization process to live in deep subterranean habitats involves a reduction of upper lethal limits, but not an adjustment to habitat temperature. Thermal variability seems to exert a higher evolutionary pressure than mean habitat temperature to configure the thermal niche of subterranean species. Our results provide novel insights on thermal physiology of species with poor dispersal capabilities and on the evolutionary process of adaptation to subterranean environments. We further emphasize that the pathways determining vulnerability of subterranean species to climate change greatly depend on the degree of specialization to deep subterranean environments.

How does landscape permeability affect the movement of eastern red‐backed salamanders?

AbstractDemographic and genetic connectivity have important implications for population dynamics of wildlife and their ability to adapt to changing environments. Landscape features such as roads and streams can inhibit movement of species with poor dispersal capabilities and exacerbate the effects of habitat fragmentation. Terrestrial plethodontid salamanders are generally thought of as incapable of long‐distance movement and may vary in their motivation to move across a landscape by sex and size classes. To examine landscape permeability to movement, we assessed how distance and natural or man‐made landscape features affect recapture rates after displacement in red‐backed salamanders (Plethodon cinereus). We randomly assigned marked salamanders from 6 plots at Camp Karoondinha in Millmont, Pennsylvania, USA, to a control (placed under the same cover board) or a treatment (displaced 25 m or 50 m through the forest or across a stream or road). Of 290 marked individuals, we recaptured 29.8%. We recaptured more individuals in the control treatment compared to displaced individuals, with recapture rates decreasing with the presence of a road or stream. Landscape feature type and sex did not affect the probability of recapture, but developmental stage did, with adult salamanders more likely to be recaptured than juvenile salamanders. Our results suggest that landscape permeability is reduced for terrestrial salamanders when a landscape feature is present compared to open forest. Narrow, dirt roads present a similar challenge to a natural stream for red‐backed salamanders. Our study should be of value to land managers who are concerned about the negative effects of landscape permeability on terrestrial salamander populations.

Thermal tolerance and vulnerability to climate change in subterranean species: a case study using an Iberian endemic pseudoscorpion

Abstract Scientists are renewing their efforts to predict the impact of climate change on biodiversity. Subterranean environments represent ideal systems to study the effect of global change in species with poor dispersal capabilities. We assess the vulnerability to climate change of the subterranean pseudoscorpion Neobisium (Blothrus) vasconicum vasconicum (Nonídez, 1925) (Neobisiidae). Thermal tolerance was measured using two complementary estimates of upper thermal limits: (i) from thermal conditions of the localities in which the species occurs (realised upper thermal limit, RUTL), and (ii) from experimentally determined thermal tolerance data (physiological upper thermal limit, PhUTL). Then, thermal safety margins (TSM) were calculated for all known localities for current and future climatic conditions, using the thermal limits from both approaches. The physiological thermal limit (PhUTL = 17.57°C) was 3.27°C higher than that obtained from the distributional and climate data (i.e., the hottest cave in which the species occurs; RUTL = 14.3°C). Regarding TSM, the future temperature (2070; RCP 8.5) of a half of the caves will be higher than the RUTL and in none of them, it would exceed the average PhUTL. This indicates that the species could have some physiological capacity to cope with warming temperatures in situ. We hypothesize that the most realistic upper thermal limit of the species could be between the RUTL and PhUTL. This study shows that complementary approaches to estimate thermal tolerance could provide more accurate predictions of the capacity to face climate change, not only in subterranean species, but also in poor dispersal species.

Conservation challenges for the most threatened family of marine bony fishes (handfishes: Brachionichthyidae)

Marine species live out-of-sight, consequently geographic range, population size and long-term trends are extremely difficult to characterise for accurate conservation status assessments. Detection challenges have precluded listing of marine bony fishes as Extinct on the International Union for Conservation of Nature (IUCN) Red List, until now (March 2020). Our data compilation on handfishes (Family Brachionichthyidae) revealed them as the most threatened marine bony fish family, with 7 of 14 species recently listed as Critically Endangered or Endangered. The family also includes the only exclusively marine bony fish to be recognised as Extinct – the Smooth handfish (Sympterichthys unipennis). Ironically, some of the characteristics that threaten handfishes with extinction have assisted assessments. Poor dispersal capabilities leading to small, fragmented populations allow monitoring and population size estimation for some shallow water species. Evidence that the Smooth handfish is now Extinct included no sightings over 200 years in an area subject to numerous scientific surveys, inferred shallow habitat and moderate abundance at time of original collection, and major habitat transformation through fishing, aquaculture, rising sea temperature, and urban development. Contemporary threats to extant handfish species include habitat degradation, introduced species, loss of spawning substrate, climate change, and demographic risks associated with small, fragmented populations. Multifaceted conservation efforts are needed, including addressing threats to habitat quality, bolstering wild population numbers, and implementing novel techniques to find and monitor populations. Expanded monitoring, including application of eDNA methods, represent critical steps towards overcoming the challenges in studying wild populations of rare marine species. Ongoing investigation will likely reveal numerous other threatened species for which little is known.

Population genetic structure and geographical variation in Neotricula aperta (Gastropoda: Pomatiopsidae), the snail intermediate host of Schistosoma mekongi (Digenea: Schistosomatidae).

BackgroundNeotricula aperta is the snail-intermediate host of the parasitic blood-fluke Schistosoma mekongi which causes Mekong schistosomiasis in Cambodia and the Lao PDR. Despite numerous phylogenetic studies only one DNA-sequence based population-genetic study of N. aperta had been published, and the origin, structure and persistence of N. aperta were poorly understood. Consequently, a phylogenetic and population genetic study was performed, with addition of new data to pre-existing DNA-sequences for N. aperta from remote and inaccessible habitats, including one new taxon from Laos and 505 bp of additional DNA-sequence for all sampled taxa,.Principal findingsSpatial Principal Component Analysis revealed the presence of significant spatial-genetic clustering. Genetic-distance-based clustering indicated four populations with near perfect match to a priori defined ecogeographical regions. Spring-dwelling taxa were found to form an ecological isolate relative to other N. aperta. The poor dispersal capabilities suggested by spatial-genetic analyses were confirmed by Bayesian inference of migration rates. Population divergence time estimation implied a mid-Miocene colonisation of the present range, with immediate and rapid radiation in each ecogeographical region. Estimated effective population sizes were large (120–310 thousand).ConclusionsThe strong spatial-genetic structure confirmed the poor dispersal capabilities of N. aperta—suggesting human-mediated reintroduction of disease to controlled areas as the primary reason for control failure. The isolation of the spring-dwelling taxa and ecogeographical structure suggests adaptation of sub-populations to different habitats; the epidemiological significance of this needs investigation. The large effective population sizes indicate that the high population densities observed in surveyed habitats are also present in inaccessible areas; affording great potential for recrudescence driven by animal-reservoir transmission in remote streams. Mid-Miocene colonisation implies heterochronous evolution of these snails and associated schistosomes and suggests against coevolution of snail and parasite. Heterochronicity favours ecological factors as shapers of host-parasite specificity and greater potential for escape from schistosomiasis control through host-switching.

A test of the substitution-habitat hypothesis in amphibians.

Most examples that support the substitution-habitat hypothesis (human-made habitats act as substitutes of original habitat) deal with birds and mammals. We tested this hypothesis in 14 amphibians by using percentage occupancy as a proxy of habitat quality (i.e., higher occupancy percentages indicate higher quality). We classified water body types as original habitat (no or little human influence) depending on anatomical, behavioral, or physiological adaptations of each amphibian species. Ten species had relatively high probabilities (0.16-0.28) of occurrence in original habitat, moderate probability of occurrence in substitution habitats (0.11-0.14), and low probability of occurrence in refuge habitats (0.05-0.08). Thus, the substitution-habitat hypothesis only partially applies to amphibians because the low occupancy of refuges could be due to the negligible human persecution of this group (indicating good conservation status). However, low occupancy of refuges could also be due to low tolerance of refuge conditions, which could have led to selective extinction or colonization problems due to poor dispersal capabilities. That original habitats had the highest probabilities of occupancy suggests amphibians have a good conservation status in the region. They also appeared highly adaptable to anthropogenic substitution habitats.

The origin of widespread species in a poor dispersing lineage (diving beetle genus Deronectes).

In most lineages, most species have restricted geographic ranges, with only few reaching widespread distributions. How these widespread species reached their current ranges is an intriguing biogeographic and evolutionary question, especially in groups known to be poor dispersers. We reconstructed the biogeographic and temporal origin of the widespread species in a lineage with particularly poor dispersal capabilities, the diving beetle genus Deronectes (Dytiscidae). Most of the ca. 60 described species of Deronectes have narrow ranges in the Mediterranean area, with only four species with widespread European distributions. We sequenced four mitochondrial and two nuclear genes of 297 specimens of 109 different populations covering the entire distribution of the four lineages of Deronectes, including widespread species. Using Bayesian probabilities with an a priori evolutionary rate, we performed (1) a global phylogeny/phylogeography to estimate the relationships of the main lineages within each group and root them, and (2) demographic analyses of the best population coalescent model for each species group, including a reconstruction of the geographical history estimated from the distribution of the sampled localities. We also selected 56 specimens to test for the presence of Wolbachia, a maternally transmitted parasite that can alter the patterns of mtDNA variability. All species of the four studied groups originated in the southern Mediterranean peninsulas and were estimated to be of Pleistocene origin. In three of the four widespread species, the central and northern European populations were nested within those in the northern areas of the Anatolian, Balkan and Iberian peninsulas respectively, suggesting a range expansion at the edge of the southern refugia. In the Mediterranean peninsulas the widespread European species were replaced by vicariant taxa of recent origin. The fourth species (D. moestus) was proven to be a composite of unrecognised lineages with more restricted distributions around the Western and Central Mediterranean. The analysis of Wolbachia showed a high prevalence of infection among Deronectes, especially in the D. aubei group, where all sequenced populations were infected with the only exception of the Cantabrian Mountains, the westernmost area of distribution of the lineage. In this group there was a phylogenetic incongruence between the mitochondrial and the nuclear sequence, although no clear pattern links this discordance to the Wolbachia infection. Our results suggest that, in different glacial cycles, populations that happened to be at the edge of the newly deglaciated areas took advantage of the optimal ecological conditions to expand their ranges to central and northern Europe. Once this favourable ecological window ended populations become isolated, resulting in the presence of closely related but distinct species in the Mediterranean peninsulas.

Thermal niche estimators and the capability of poor dispersal species to cope with climate change.

For management strategies in the context of global warming, accurate predictions of species response are mandatory. However, to date most predictions are based on niche (bioclimatic) models that usually overlook biotic interactions, behavioral adjustments or adaptive evolution, and assume that species can disperse freely without constraints. The deep subterranean environment minimises these uncertainties, as it is simple, homogeneous and with constant environmental conditions. It is thus an ideal model system to study the effect of global change in species with poor dispersal capabilities. We assess the potential fate of a lineage of troglobitic beetles under global change predictions using different approaches to estimate their thermal niche: bioclimatic models, rates of thermal niche change estimated from a molecular phylogeny, and data from physiological studies. Using bioclimatic models, at most 60% of the species were predicted to have suitable conditions in 2080. Considering the rates of thermal niche change did not improve this prediction. However, physiological data suggest that subterranean species have a broad thermal tolerance, allowing them to stand temperatures never experienced through their evolutionary history. These results stress the need of experimental approaches to assess the capability of poor dispersal species to cope with temperatures outside those they currently experience.

The ant Anochetus ghilianii (Hymenoptera, Formicidae), not a Tertiary relict, but an Iberian introduction from North Africa: Evidence from mtDNA analyses

Anochetus ghilianii is the only species of the genus Anochetus found in Europe. Its presence in the southernmost region of the Iberian Peninsula (Province of Cadiz) is puzzling. Anochetus ghilianii's poor dispersal capabilities (colony foundation by foot and wingless queens) suggest that its presence in the Iberian Peninsula must be ancient, dating to from at least the last connection period between both Spain and Africa around 5 million years ago. In the Iberian Peninsula, this species is only found at low altitude coastal localities, whereas its mainland counterpart populations of North Morocco show a more widespread distribution, also found at higher altitude inland. In this study, we sequenced a fragment of a rapidly evolving mitochondrial gene (COI) from several individuals throughout the species' Moroccan and Iberian distribution range. The results from the Bayesian Inference (BI) and Median-Joining analyses showed a genetic pattern of decreasing haplotypic diversity from southern to northern localities. Furthermore, our results recovered the same haplotype from all the Iberian localities and from Cap Spartel and Tangier in North Morocco. We attribute this lack of genetic divergence to multiple reoccurring translocations through maritime traffic between ports on either side of the Strait of Gibraltar. Our study raises the concern that two other ants, Technomyrmex vexatus and Stigmatomma emeryi, also believed to be Tertiary relicts with a similar distribution pattern to A. ghilianii, may have also been introduced accidentally in the Iberian Peninsula.

The southwestern Carpathians as an ancient centre of diversity of freshwater gammarid amphipods: insights from the Gammarus fossarum species complex.

Gammarus fossarum is a diverse species complex of epigean freshwater amphipods throughout Europe. Due to their poor dispersal capabilities and ubiquity, these crustaceans may serve as a model for investigating the influence of historical factors on the contemporary distribution and diversity patterns of freshwater macrozoobenthos. Here, we investigate the fine-scale phylogeographic structure of this complex across its range in the southwestern Carpathian Mountains, which comprises two areas that are geographically isolated from its main European distribution area as well as from each other. Given the Tertiary age of many freshwater Gammarus species, we hypothesize that the southwestern Carpathian populations reflect a relict distribution pattern. We used two mitochondrial and three nuclear markers from 32 localities to reconstruct phylogenetic relationships and estimate the timings of divergence among southwestern Carpathian and non-Carpathian lineages. Cryptic diversity was evaluated from mitochondrial markers by employing phylogenetic and distance-based methods. We distinguished at least 16 cryptic microendemic taxa, some of them coexisting, distributed in the southwestern Carpathians in a mosaic-like pattern. These lineages form a monophyletic group together with several lineages from southeastern Europe. Estimated divergence times indicate a Middle Miocene origin of this clade, with many deep splits dating back to more than 10Ma. This time frame corresponds with a period of intense geological subsidence in the region that gave birth to the Pannonian Basin. We conclude that subsidence could have been an important driver of diversification in freshwater Gammarus and that the southwestern Carpathians represent an ancient centre of diversity for these crustaceans.

A snail perspective on the biogeography of Sulawesi, Indonesia: origin and intra-island dispersal of the viviparous freshwater gastropod Tylomelania.

The complex geological history of the Indonesian island Sulawesi has shaped the origin and subsequent diversification of its taxa. For the endemic freshwater snail Tylomelania a vicariant origin from the Australian margin has been hypothesized. Divergence time estimates from a mtDNA phylogeny based on a comprehensive island-wide sampling of Tylomelania fit regional tectonic constraints and support the ‘out-of-Australia’ vicariance hypothesis. The Banggai-Sula region of the Sula Spur, the Australian promontory colliding with West Sulawesi during the Miocene, is identified as a possible source area for the colonization of Sulawesi by the ancestor of Tylomelania. The molecular phylogeny also shows a rapid diversification of Tylomelania into eight major lineages with very little overlap in their distribution on the island. Haplotype networks provide further evidence for a strong spatial structure of genetic diversity in Tylomelania. Distribution boundaries of the major lineages do at best partially coincide with previously identified contact zones for other endemic species groups on Sulawesi. This pattern has likely been influenced by the poor dispersal capabilities and altitudinal distribution limits of this strict freshwater inhabitant. We suggest that late Miocene and Pliocene orogeny in large parts of Sulawesi has been the vicariant event driving primary diversification in Tylomelania.

Cryptic habitats and cryptic diversity: unexpected patterns of connectivity and phylogeographical breaks in a Mediterranean endemic marine cave mysid.

The marine cave-dwelling mysid Hemimysis margalefi is distributed over the whole Mediterranean Sea, which contrasts with the poor dispersal capabilities of this brooding species. In addition, underwater marine caves are a highly fragmented habitat which further promotes strong genetic structuring, therefore providing highly informative data on the levels of marine population connectivity across biogeographical regions. This study investigates how habitat and geography have shaped the connectivity network of this poor disperser over the entire Mediterranean Sea through the use of several mitochondrial and nuclear markers. Five deeply divergent lineages were observed among H.margalefi populations resulting from deep phylogeographical breaks, some dating back to the Oligo-Miocene. Whether looking at the intralineage or interlineage levels, H.margalefi populations present a high genetic diversity and population structuring. This study suggests that the five distinct lineages observed in H.margalefi actually correspond to as many separate cryptic taxa. The nominal species, H.margalefi sensu stricto, corresponds to the westernmost lineage here surveyed from the Alboran Sea to southeastern Italy. Typical genetic breaks such as the Almeria-Oran Front or the Siculo-Tunisian Strait do not appear to be influential on the studied loci in H.margalefi sensu stricto. Instead, population structuring appears more complex and subtle than usually found for model species with a pelagic dispersal phase. The remaining four cryptic taxa are all found in the eastern basin, but incomplete lineage sorting is suspected and speciation might still be in process. Present-day population structure of the different H.margalefi cryptic species appears to result from past vicariance events started in the Oligo-Miocene and maintained by present-day coastal topography, water circulation and habitat fragmentation.

Eucalypts and Their Potential for Invasiveness Particularly in Frost-Prone Regions

Eucalypts are being considered for biofuel production in the Lower Coastal Plain of the United States. The evolution of eucalypts in Australia has equipped some species to be successful in plantations and has also influenced their potential as invasive species. More than 200 eucalypt species have been evaluated in many countries around the world. Generally eucalypts have proved to have limited invasive potential for a number of reasons, including their poor dispersal capabilities. Two regions with climates similar to the Lower Coastal Plain of the United States are identified in Argentina and China. Frosts, particularly sudden frosts, are an important limitation for eucalypts in these regions, so existing plantations are very limited. However, invasive eucalypts do not appear to be a major problem in other regions of either country. The use of carefully selected frost-tolerant species and the development of genetically modified eucalypts may now open up more frost-affected areas for eucalypt plantations. Some control actions may be necessary and research needs are outlined, but it is concluded that experience in other regions around the world suggests that eucalypts are likely to be a relatively low risk as invasive species in the Lower Coastal Plain.

Terrestrial Turtle Fossils from New Zealand Refloat Moa's Ark

Two fossils from the diverse St Bathans Fauna from Early Miocene sediments in New Zealand are described and identified as from a large, probably terrestrial turtle. They are the first freshwater or terrestrial turtles to have been reported from the Cenozoic of New Zealand. Recent authors have used the absence of turtles and species they considered unlikely to raft to New Zealand to debunk the long held theory that an element of the New Zealand fauna was ancient and vicariant and had evolved on what David Bellamy called Moa's Ark. The discovery that large non-marine turtles were once present in New Zealand adds to a growing and diverse list of terrestrial taxa known from Zealandia shortly after its maximum inundation in the Late Oligocene. Many of these taxa, including a diverse herpetofaunal component, represent lineages endemic to New Zealand and had poor dispersal capabilities, supporting the long held view that a part of the Zealandian fauna was vicariant in origin.

Strong Population Genetic Structure in a Broadcast-Spawning Antarctic Marine Invertebrate

Although studies of population genetic structure are commonplace, a strong bias exists toward species from low latitudes and with relatively poor dispersal capabilities. Consequently, we used 280 amplified fragment length polymorphism bands to explore patterns of genetic differentiation among 8 populations of a high latitude broadcast-spawning marine mollusc, the Antarctic limpet Nacella concinna. Over 300 individuals were sampled along a latitudinal gradient spanning the Antarctic Peninsula from Adelaide Island to King George Island (67°-62°S), then to Signy Island (60°S) and South Georgia (54°S). Populations from the Antarctic Peninsula exhibited little genetic structure but were themselves strongly differentiated from both Signy and South Georgia. This finding was analytically highly robust and implies the presence of significant oceanographic barriers to gene flow in a species long regarded as a classic example of a widely dispersing broadcast spawner.

A revision of the Australian handfishes (Lophiiformes: Brachionichthyidae), with descriptions of three new genera and nine new species

The family Brachionichthyidae is represented by at least 14 small, Australian endemic, lophiiform fishes distributed from central eastern Australia to the Great Australian Bight. All but three of these species occur in the seas off Tasmania. The group is comprised of two recognised genera, Brachionichthys Bleeker and Sympterichthys Gill, and three new genera, Brachiopsilus gen. nov., Pezichthys gen. nov. and Thymichthys gen. nov. Nine of the 14 species are undescribed. The type genus, Brachionichthys, consists of B. hirsutus (Lacepède) and B. australis Last, Gledhill & Holmes. These species, which are covered with long, unicuspid spinules and a strong colour pattern of dark spots and streaks, typically have 7 pectoral-fin rays. The genus Sympterichthys includes one of Australia’s earliest described fishes, S. unipennis (Cuvier), and a new taxon S. moultoni sp. nov. Members of the genus lack warts and dermal appendages on the skin but are covered in small embedded scales with adpressed, unicuspid and bicuspid spinules originating from the posterior margin of their bases. Brachiopsilus contains three new species: B. dianthus sp. nov., B. dossenus sp. nov. and B. ziebelli sp. nov. These handfishes, which are amongst the largest members of the family (reaching 117 mm SL), are smooth skinned (without spinules, dermal appendages or fleshy warts), are vividly coloured in life (without extensive blackish markings), and have 9–10 pectoral-fin rays. A fourth genus, Pezichthys, is not fully resolved and may be polyphyletic. It provisionally consists of five undescribed species: P. amplispinus sp. nov., P. compressus sp. nov., P. eltanini sp. nov., P. macropinnis sp. nov. and P. nigrocilium sp. nov. These species are variably covered in erect, bicuspid spinules, and all have 7 pectoral-fin rays. Thymichthys contains two old species-level taxa, T. politus (Richardson) and T. verrucosus (McCulloch & Waite), both previously placed in Sympterichthys. Members of the genus Thymichthys have an ornate skin variably covered with wart-like protuberances, dermal appendages and a sparse coverage of scales with their spinules not or barely penetrating the skin surface. Regional morphs exist for Thymichthys verrucosus which may represent an unresolved species complex. New study material and a molecular study of these populations across their ranges are needed to determine their relationships. Other characters useful in defining the brachionichthyid genera, and distinguishing species, include illicial morphology, coloration, characteristics of the skin, including the form and degree of coverage and exposure of spiny scales, and selected morphometrics and meristics. Historical and current ecological data confirms that these fishes have specialised habitat requirements, patchy distributions and poor dispersal capabilities, making them amongst the most vulnerable of marine fishes. The fossil record suggests that the group was once much more widespread and their restricted extant distribution in Australia may be linked to regional extinction due to their life history strategy.

Mitochondrial phylogeographic structure of the white‐browed piculet (Sasia ochracea): cryptic genetic differentiation and endemism in Indochina

AbstractAim Our understanding of the geographic patterns of gene flow between populations of birds in the Indo‐Malayan faunal region is surprisingly poor compared with that in other parts of the world. A thorough knowledge of general patterns of phylogeographic structure is, however, of utmost importance for conservation purposes. Species with poor dispersal capabilities could serve as indicators of endemism and genetic isolation in the Indochinese subregion. From their morphology (tiny size, short tail, short and rounded wings), piculets of the genus Sasia are inferred to have poor dispersal capabilities, and thus form a suitable focal species. This study analysed the pattern of genetic variation within the White‐browed Piculet (Sasia ochracea).Location Southeast Asia, north of the Isthmus of Kra.Methods We sampled 43 individuals throughout the breeding range of S. ochracea. DNA was extracted both from fresh tissues (n = 15) and from toe pads from ancient museum skins (n = 28). We amplified a 801‐bp fragment of the mitochondrial ND2 gene to reconstruct the phylogeographic history of the White‐browed Piculet. The sequence data were analysed using Bayesian inference, statistical parsimony, and population genetics methods (analysis of molecular variance, mismatch distributions). We estimated the amount of ongoing gene flow between populations using the coalescent‐based method implemented in Mdiv.Results The analysis of molecular variance indicated that the current taxonomy does not adequately reflect the amount of genetic variation within S. ochracea, as the great majority of genetic variation was nested within the nominal subspecies, which is distributed from Nepal to southern Vietnam. Bayesian inference analyses and haplotype networks suggested the occurrence of five main lineages that are strongly correlated with geography. Our coalescent‐based analyses indicated a very limited amount of ongoing gene flow between these five lineages. Our dating analyses suggested that the genetic structuring probably occurred during the last 400,000 years.Main conclusions Our analyses revealed that S. ochracea is composed of at least five lineages: south Vietnam (South Annam and ‘Cochinchina’), India and Nepal, Myanmar and India, the remainder of Indochina, and probably southern Myanmar (Tenasserim). We strongly recommend that studies aiming to understand the phylogeographic structure within Indo‐Malayan species sample these areas.