Kinematics of prey capture in the tailed frog Ascaphus truei (Anura: Ascaphidae)

The kinematics of prey capture by Ascaphus truei was investigated. High-speed films (100 fps) of 13 successful and one unsuccessful prey capture sequences from six adult frogs were analysed. Ascaphus , the sister group of all living frogs, shares several aspects of feeding kinematics, including rotation of the tongue pad about the mandibular symphysis and mandibular bending during mouth opening and closing, with more derived frogs such as Bufo marinus. The times required for tongue retraction, mouth opening and closing are similar in Ascaphus and Bufo. However, because Bufo is much larger and protracts its tongue much farther than Ascaphus , the velocities of tongue retraction, mouth opening and mouth closing are relatively lower in Ascaphus than in Bufo. Differences in prey capture between Ascaphus and Bufo marinus are (1) the distance of tongue protraction is less in Ascaphus (±0.5 cm) than in Bufo (c. 2 cm); and (2) lunging of the whole body is more pronounced in Ascaphus. Prey capture is highly variable in Ascaphus. An intraoral transport sequence is sometimes (7 of 14 observations) inserted into the prey capture cycle before the completion of mouth closing. The gape cycles range from 80–150 ms for sequences with no oral transport and from 130–280 ms for sequences with oral transport. Also, the time required for tongue retraction is significantly longer in the unsuccessful capture attempt. This variability is generally greater than that observed during prey capture in salamanders, and suggests that frogs and salamanders may differ in the importance of sensory feedback in coordinating prey capture.     

Landscape genetic structure of coastal tailed frogs (Ascaphus truei) in protected vs. managed forests

Habitat loss and fragmentation are the leading causes of species’ declines and extinctions. A key component of studying population response to habitat alteration is to understand how fragmentation affects population connectivity in disturbed landscapes. We used landscape genetic analyses to determine how habitat fragmentation due to timber harvest affects genetic population connectivity of the coastal tailed frog (Ascaphus truei), a forest-dwelling, stream-breeding amphibian. We compared rates of gene flow across old-growth (Olympic National Park) and logged landscapes (Olympic National Forest) and used spatial autoregression to estimate the effect of landscape variables on genetic structure. We detected higher overall genetic connectivity across the managed forest, although this was likely a historical signature of continuous forest before timber harvest began. Gene flow also occurred terrestrially, as connectivity was high across unconnected river basins. Autoregressive models demonstrated that closed forest and low solar radiation were correlated with increased gene flow. In addition, there was evidence for a temporal lag in the correlation of decreased gene flow with harvest, suggesting that the full genetic impact may not appear for several generations. Furthermore, we detected genetic evidence of population bottlenecks across the Olympic National Forest, including at sites that were within old-growth forest but surrounded by harvested patches. Collectively, this research suggests that absence of forest (whether due to natural or anthropogenic changes) is a key restrictor of genetic connectivity and that intact forested patches in the surrounding environment are necessary for continued gene flow and population connectivity.     

Olfactory metamorphosis in the coastal tailed frog Ascaphus truei (Amphibia,Anura, Leiopelmatidae)

The structure of the olfactory organ in larvae and adults of the basal anuran Ascaphus truei was examined using light micrography, electron micrography, and resin casts of the nasal cavity. The larval olfactory organ consists of nonsensory anterior and posterior nasal tubes connected to a large, main olfactory cavity containing olfactory epithelium; the vomeronasal organ is a ventrolateral diverticulum of this cavity. A small patch of olfactory epithelium (the “epithelial band”) also is present in the preoral buccal cavity, anterolateral to the choana. The main olfactory epithelium and epithelial band have both microvillar and ciliated receptor cells, and both microvillar and ciliated supporting cells. The epithelial band also contains secretory ciliated supporting cells. The vomeronasal epithelium contains only microvillar receptor cells. After metamorphosis, the adult olfactory organ is divided into the three typical anuran olfactory chambers: the principal, middle, and inferior cavities. The anterior part of the principal cavity contains a “larval type” epithelium that has both microvillar and ciliated receptor cells and both microvillar and ciliated supporting cells, whereas the posterior part is lined with an “adult‐type” epithelium that has only ciliated receptor cells and microvillar supporting cells. The middle cavity is nonsensory. The vomeronasal epithelium of the inferior cavity resembles that of larvae but is distinguished by a novel type of microvillar cell. The presence of two distinct types of olfactory epithelium in the principal cavity of adult A. truei is unique among previously described anuran olfactory organs. A comparative review suggests that the anterior olfactory epithelium is homologous with the “recessus olfactorius” of other anurans and with the accessory nasal cavity of pipids and functions to detect water‐borne odorants. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.     

Early development of chondrocranium in the tailed frog Ascaphus truei (Amphibia: Anura): Implications for anuran palatoquadrate homologies

Chondrocranial development in Ascaphus truei was studied by serial sectioning and graphical reconstruction. Nine stages (21–29; 9–18 mm TL) were examined. Mesodermal cells were distinguished from ectomesenchymal (neural crest derived) cells by retained yolk granules. Ectomesenchymal parts of the chondrocranium include the suprarostrals, pila preoptica, anterior trabecula, and palatoquadrate. Mesodermal parts of the chondrocranium include the orbital cartilage, posterior trabecula, parachordal, basiotic lamina, and otic capsule. Development of the palatoquadrate is as follows. The pterygoid process first connects with the trabecula far rostrally; their fusion progresses caudally. The ascending process connects with a mesodermal bar that extends from the orbital cartilage to the otic capsule, and forms the ventral border of the dorsal trigeminal outlet. This bar is the “ascending process” of Ascaphus adults; it is a neurocranial, not palatoquadrate structure. The basal process chondrifies in an ectomesenchymal strand running from the quadrate keel to the postpalatine commissure. Later, the postpalatine commissure and basal process extend anteromedially to contact the floor of the anterior cupula of the otic capsule, creating separate foramina for the palatine and hyomandibular branches of the facial nerve. Based on these data, and on comparison with other frogs and salamanders, the anuran anterior quadratocranial commissure is homologized with the pterygoid process of salamanders, the anuran basal process (=“pseudobasal” or “hyobasal” process) with the basal process of salamanders, and the anuran otic ledge with the basitrabecular process of salamanders. The extensive similarities in palatoquadrate structure and development between frogs and salamanders, and lacking in caecilians, are not phylogenetically informative. Available information on fossil outgroups suggests that some of these similarities are primitive for Lissamphibia, whereas for others the polarity is uncertain. J. Morphol. 231:63-100, 1997. © 1997 Wiley-Liss, Inc.     

Phylogeography of western Pacific Leucetta 'chagosensis' (Porifera: Calcarea) from ribosomal DNA sequences: implications for population history and conservation of the Great Barrier Reef World Heritage Area (Australia)

Leucetta 'chagosensis' is a widespread calcareous sponge, occurring in shaded habitats of Indo-Pacific coral reefs. In this study we explore relationships among 19 ribosomal DNA sequence types (the ITS1-5.8S-ITS2 region plus flanking gene sequences) found among 54 individuals from 28 locations throughout the western Pacific, with focus on the Great Barrier Reef (GBR). Maximum parsimony analysis revealed phylogeographical structuring into four major clades (although not highly supported by bootstrap analysis) corresponding to the northern/central GBR with Guam and Taiwan, the southern GBR and subtropical regions south to Brisbane, Vanuatu and Indonesia. Subsequent nested clade analysis (NCA) confirmed this structure with a probability of > 95%. After NCA of geographical distances, a pattern of range expansion from the internal Indonesian clade was inferred at the total cladogram level, as the Indonesian clade was found to be the internal and therefore oldest clade. Two distinct clades were found on the GBR, which narrowly overlap geographically in a line approximately from the Whitsunday Islands to the northern Swain Reefs. At various clade levels, NCA inferred that the northern GBR clade was influenced by past fragmentation and contiguous range expansion events, presumably during/after sea level low stands in the Pleistocene, after which the northern GBR might have been recolonized from the Queensland Plateau in the Coral Sea. The southern GBR clade is most closely related to subtropical L. 'chagosensis', and we infer that the southern GBR probably was recolonized from there after sea level low stands, based on our NCA results and supported by oceanographic data. Our results have important implications for conservation and management of the GBR, as they highlight the importance of marginal transition zones in the generation and maintenance of species rich zones, such as the Great Barrier Reef World Heritage Area.     

Phylogeography of the chestnut‐tailed antbird (Myrmeciza hemimelaena) clarifies the role of rivers in Amazonian biogeography

Aim We examined patterns of spatial and temporal diversification of the Amazonian endemic chestnut‐tailed antbird, Mymeciza hemimelaena (Thamnophilidae), to evaluate the diversification of a widespread avian taxon across rivers that potentially represent major natural barriers. Location Lowland Amazonia. Methods Sequences of the mitochondrial ND2 and cytochrome b genes were investigated from 65 individuals distributed throughout the entire range of M. hemimelaena, and including the two currently valid subspecies M. h. hemimelaena and M. h. pallens. Based on a combination of phylogeographic tools, molecular dating, and population genetic methods, we reconstructed a spatio‐temporal scenario of diversification of M. hemimelaena in the Amazon. Results The data revealed three genetically divergent and monophyletic groups in M. hemimelaena, which can also be distinguished by a combination of morphological and vocal characters. Two of these clades correspond to the previously described taxa M. h. hemimelaena and M. h. pallens, which are separated by the upper Madeira River, a main Amazonian tributary. The third clade is distributed between the middle reaches of the Madeira River and the much smaller tributaries Jiparaná and Aripuanã, and, although currently treated as M. h. pallens, clearly constitutes an independent evolutionary lineage probably deserving separate species status. Molecular clock and population genetic analyses indicate that diversification in this group occurred throughout the Pleistocene, with demographic fluctuations assumed for M. h. hemimelaena and M. h. pallens. Main conclusions The findings implicate rivers as barriers driving diversification in the M. hemimelaena complex. Levels of mitochondrial DNA divergence and associated morphological and vocal traits support its division into at least three separate species with comparatively small ranges. The existence of a previously unrecognized lineage in the M. hemimelaena complex, and the high degree of population structuring found in M. h. hemimelaena underscore the pervasiveness of cryptic endemism throughout Amazonia and the importance of DNA‐based taxonomic and phylogeographic studies in providing the accurate estimates of diversity that are essential for conservation planning.     

Phylogeography and conservation genetics of the Columbia spotted frog (Rana luteiventris; Amphibia, Ranidae)

The Columbia spotted frog (Rana luteiventris) has a widespread distribution in western Canada and the western US, although the southern reach of its range is highly fragmented into several isolated populations. Threats from various factors have raised concerns regarding the long-term survival of many small, isolated populations. Here, we report a study designed to determine the phylogeographic and conservation genetic parameters of R. luteiventris in the western US. Mitochondrial DNA (mtDNA) sequences were examined for phylogeographic structuring using phylogenetic reconstruction methods, coupled with networking and nested clade analyses. These methods permitted a distinction to be made between historic and demographic forces acting to generate geographical patterning of genetic variation. Phylogenetic analysis revealed four geographically correlated monophyletic clades. Three of these clades correspond to well-defined, nonoverlapping geographical locations in the fragmented portion of the range. The other is comprised of all samples collected from the contiguous range and includes one isolate from northern Wyoming. Networking and nested clade analyses confirmed these results and revealed that historical processes, such as range expansion and vicariance, rather than recurrent gene flow are likely responsible for observed patterns of genetic variation. A measure of genetic variation (theta = 4N(e)mu) revealed that R. luteiventris populations in Utah have a relatively low amount of genetic variation compared with populations in the continuous portion of the range.     

Phylogeography of the red-tailed chipmunk (Tamias ruficaudus), a northern Rocky Mountain endemic

The northern Rocky Mountains have experienced a complex history of geological events and environmental fluctuation, including Pleistocene glaciation. To provide an initial assessment of the genetic impact of this history on the regional biota we estimated phylogenetic relationships within Tamias ruficaudus, a regional endemic, from cytochrome b sequence variation using parsimony, maximum likelihood, and nested clade analysis. Analyses of sequence variation in 187 individuals from 43 localities across the distribution of T. ruficaudus indicate a history of vicariance events and range fluctuation consistent with successive periods of extensive Pleistocene glaciation in the northern Rocky Mountains. Intraspecific divergence levels (c. 4.7% uncorrected) and phylogenetic structure are consistent with a genealogical vicariance initiated prior to the Late Pleistocene, whereas nested clade analyses indicate more recent population history structured by both fragmentation and range expansion. A comparison of sequence variation with bacular morphology indicates that the two genetically and morphologically differentiated entities exhibit a zone of differential character introgression. Sequence data support a multiple refugia hypothesis and provide a phylogeographical case study for the ongoing synthesis of regional biogeography for northern Rocky Mountain endemics.     

Molecular systematics of Selenops spiders (Araneae: Selenopidae) from North and Central America: implications for Caribbean biogeography

The Caribbean region includes a geologically complex mix of islands, which have served as a backdrop for some significant studies of biogeography, mostly with vertebrates. Here, we use the tropical/subtropical spider genus Selenops (Selenopidae) to obtain a finer resolution of the role of geology in shaping patterns of species diversity. We obtained a broad geographic sample from over 200 localities from both the islands and American mainland. DNA sequence data were generated for three mitochondrial genes and one nuclear gene for eleven outgroup taxa and nearly 60 selenopid species. Phylogenetic analysis of the data revealed several biogeographic patterns common to other lineages that have diversified in the region, the most significant being: (1) a distinct biogeographic break between Northern and Southern Lesser Antilles, although with a slight shift in the location of the disjunction; (2) diversification within the islands of Jamaica and Hispaniola; (3) higher diversity of species in the Greater Antilles relative to the Lesser Antilles. However, a strikingly unique pattern in Caribbean Selenops is that Cuban species are not basal in the Caribbean clade. Analyses to test competing hypotheses of vicariance and dispersal support colonization through GAARlandia, an Eocene–Oligocene land span extending from South America to the Greater Antilles, rather than over‐water dispersal. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 288–322.     

Phylogeography of shy and white-capped albatrosses inferred from mitochondrial DNA sequences: implications for population history and taxonomy

The evolutionary relationship between shy (Thalassarche cauta) and white-capped (T. steadi) albatrosses was examined using mitochondrial control region sequences. Results were interpreted in the context of a recent and contentious taxonomic revision that recommended full species status for shy and white-capped albatrosses. Low sequence divergence between shy and white-capped albatrosses (1.8%) and between their close relatives, Salvin's and Chatham albatrosses (2.9%), was observed. Much higher sequence divergence was found between the shy/white-capped pair and the Salvin's/Chatham pair (7.0%). Phylogenetic analyses confirmed the separation of the shy/white-capped pair from the Salvin's/Chatham pair but did not provide species-level resolution. Phylogeographic analyses, including a nested clade analysis, FST estimates and an analysis of molecular variance, indicated unambiguous genetic structuring between shy and white-capped albatrosses, thus confirming the demographic isolation of the species, but showed little to no structuring within each species. The geographical distribution of mtDNA haplotypes and other evidence suggest that shy albatrosses arose through range expansion by white-capped albatrosses.     

The distribution of the Rocky Mountain tailed frog (Ascaphus montanus) in relation to the fluvial system: implications for management and conservation

The mating, egg-laying, and larval development of tailed frogs occur in dynamic mountain streams. During the lengthy (up to 5 years) aquatic residency these species are vulnerable to channel disturbances that can be exacerbated by land uses. Researchers have highlighted specific tailed frog habitat associations but never in the context of fluvial system processes. Based on an extensive regional study with a watershed-wide sampling strategy, we demonstrate that the Rocky Mountain tailed frog (Ascaphus montanus) is limited to contributing basins of roughly 0.3–100 km² in size, with peak numbers in basins up to 35 km². We conclude that the primary determinant of tailed frog distribution patterns in a watershed is basin area, a proximate variable for channel process domain and regional stream discharge: tailed frogs are adapted to cascade and step-pool channel morphologies that characterize these small basins, presumably because they afford more bedform stability and pore-space refugia than do smaller, colluvial headwaters, or larger, floodplain-forming plane bed and pool-riffle bedforms of mainstem rivers. Secondarily, climate and physiography interact to influence occurrence and abundance at the watershed level by controlling such variables as runoff, water temperature, and sedimentation regime. This point has important management implications because it forces us to recognize that in complex ecosystems, wildlife habitat associations are contingent on site-specific interactions amongst fluvial system control variables: significance levels of any one variable to tailed frog distribution will not necessarily be consistent among basins. The study clearly shows that case studies can produce conflicting results when they lack a process-based understanding of ecological response.     

Stream Restoration in the Pacific Northwest: Analysis of Interviews with Project Managers

Hundreds of millions of dollars per year are spent on river restoration in the Pacific Northwest (PNW), but little is known about the effectiveness of this effort. To help address this gap, we analyzed a database containing 23,000 projects at 35,000 locations in the region. We selected a subset of these projects for interviews using a survey instrument developed by a national team of scientists. In total, 47 project contacts in the PNW were interviewed to learn from the individuals directly involved in restoration. At least one‐third of the projects surveyed (34%) did not conduct sufficient monitoring to evaluate effectiveness. More than two‐thirds (70%) of all respondents reported their projects were successful, but 43% either have no success criteria or are unaware of any criteria for their project. Although almost two‐thirds (66%) of respondents anticipate a need for ongoing project maintenance, less than half (43%) have maintenance funds available. These findings suggest that establishing a connection between effectiveness monitoring and project implementation is not a usual component of project design. Consequently, we can only assess the benefits in a few isolated projects and cannot quantify the cumulative benefits of restoration on a larger scale. These findings highlight the need for (1) planning prior to implementation of restoration projects that accounts for monitoring design; (2) coordinated effectiveness monitoring to assess cumulative effects of restoration; and (3) management and maintenance of projects based on real measures of project performance.     

Geographic Variation in Roost-Site Selection of Long-Legged Myotis in the Pacific Northwest

Abstract: Several species of bats in the Pacific Northwest of the United States, including long-legged myotis (Myotis volans), are dependent on snags in coniferous forests during summer for roosting and rearing young. Thus, data on roosting preferences of this species are needed to integrate their habitat requirements into shifting plans for management of forests in this region. Therefore, from 2001 to 2006, we radiotracked adult female long-legged myotis (n = 153) to day roosts (n = 395) across 6 watersheds in Washington, Oregon, and Idaho, USA, and compared characteristics associated with roosting sites to those of random snags (n = 260) sampled in the same watersheds using use-availability logistic regression and an information-theoretic approach. Model rankings varied among geographic locations, with quantity of stem surface for roosting the best model for explaining roost-site selection of long-legged myotis in both Washington and Oregon. Model rankings for populations of bats in Idaho found stand- and landscape-scale features to be important in roost-site selection, with a habitat fragmentation model and a foraging habitat quality model both demonstrating strong support as best model. Choice of day roosts by long-legged myotis was associated with snags that were taller, intact at the top of the stem, possessing a greater amount of exfoliating bark, in stands with a larger basal area of dead stems, and in landscapes that were unfragmented (i.e., supporting lesser amounts of edge). Results indicate that roost-site selection of bats in western coniferous forests, particularly long-legged myotis, is likely to be region-specific. We encourage land managers to consider importance of geographic variation in intraspecific habitat use in forest-dwelling bats when implementing silvicultural systems to promote biological diversity in actively managed forests of the Pacific Northwest region.     

Differentiation between populations of a termite in eastern Africa: implications for biogeography

Aim  African forests are divided by an arid corridor which runs from the Horn of Africa to the Namib Desert. Several forest species occur in the forests of eastern Africa as well as in the Guineo-Congolian forest block. We evaluate the possibility that such species may have crossed the arid corridor along a route through the Kenyan Highlands and down the eastern drainages during climatologically favourable periods in the past.
Locations  Eastern Africa, Ivory Coast.
Methods  We used the termite species Schedorhinotermes lamanianus (Sjöstedt). This species occurs in lowland forests and woodland throughout Africa south of the Sahara. We sampled termites from 12 populations. We evaluated the differentiation between populations using amplified fragment length polymorphisms as well as morphometrical measurements.
Results  Genetic and morphometrical analysis demonstrated substantial differentiation between populations west and east of the arid corridor in Kenya. To the east of this corridor we found an increase of morphological distance with geographical distance. Schedorhinotermes lamanianus occurs not only along the coast but also at isolated locations (e.g. ground-water forests in foothills) within the arid hinterland.
Main conclusions  We interpret these populations as remnants of a wider distribution during wet climatic periods. At these times, populations of S. lamanianus were apparently able to establish along extensive gallery forests protruding into the arid belt of the Kenyan hinterland. There have been no connections between populations of this species east and west of the arid corridor across the Kenyan Highlands.     

Historical biogeography of Melicope (Rutaceae) and its close relatives with a special emphasis on Pacific dispersals

The genus Melicope (Rutaceae) occurs on most Pacific archipelagos and is perfectly suited to study Pacific biogeography. The main goal was to infer the age, geographic origin and colonization patterns of Melicope and its relatives. We sequenced three nuclear and two plastid markers for 332 specimens that represent 164 species in 16 genera of Rutaceae. Phylogenetic reconstruction, molecular dating, ancestral area reconstruction and diversification analyses were carried out. The two main clades (Acronychia‐Melicope and Euodia) originated in Australasia and their crown ages are dated to the Miocene. Diversification rates differed among the subclades and were lowest in the Euodia lineage and highest in the Hawaiian Melicope lineage. The Malagasy and Mascarene species form a clade, which split from its SE Asian relatives in the Pliocene/Pleistocene. At least eight colonizations to the Pacific islands occurred. The timing of all colonizations except for the Hawaiian group is congruent with age of the island ages. Australia, New Guinea and New Caledonia have been the source of colonizations into the Pacific islands in the Melicope clade. Melicope shows high dispersability and has colonized remote archipelagos such as the Austral and Marquesas Islands each twice. Colonization of islands of the Hawaiian‐Emperor seamount chain likely predates the ages of the current main islands, and the initial colonization to Kaua'i occurred after the splitting of the Hawaiian lineage into two subclades. Wider ecological niches and adaptations to bird‐dispersal likely account for the much higher species richness in the Acronychia‐Melicope clade compared to the Euodia clade.     

Phylogeography and introgressive hybridization: chipmunks (genus Tamias) in the northern Rocky Mountains

Abstract. If phylogeographic studies are to be broadly used for assessing population-level processes relevant to speciation and systematics, the ability to identify and incorporate instances of hybridization into the analytical framework is essential. Here, we examine the evolutionary history of two chipmunk species, Tamias ruficaudus and Tamias amoenus , in the northern Rocky Mountains by integrating multivariate morphometrics of bacular (os penis) variation, phylogenetic estimation, and nested clade analysis with regional biogeography. Our results indicate multiple examples of mitochondrial DNA introgression layered within the evolutionary history of these nonsister species. Three of these events are most consistent with recent and/or ongoing asymmetric introgression of mitochondrial DNA across morphologically defined secondary contact zones. In addition, we find preliminary evidence where a fourth instance of nonconcordant characters may represent complete fixation of introgressed mitochondrial DNA via a more ancient hybridization event, although alternative explanations of convergence or incomplete sorting of ancestral polymorphisms cannot be dismissed with these data. The demonstration of hybridization among chipmunks with strongly differentiated bacular morphology contradicts long-standing assumptions that variation within this character is diagnostic of complete reproductive isolation within Tamias . Our results illustrate the utility of phylogeographic analyses for detecting instances of reticulate evolution and for incorporating this and other information in the inference of the evolutionary history of species.     

Developmental anatomy of the tailed frog (As cap hits truei): a primitive frog with large eggs and slow development

The embryonic and early larval development of Ascaphus was studied by culturing embryos at 11 °C. Twenty stages of normal development are morphologically defined by using a standard staging system for anuran amphibians.
Cleavage stages are distinctive. The first cell division is unique because two separate furrows develop and then fuse to form a single cleavage plane. The large, yolky cytoplasm continues to influence cell divisions, and a blastula develops with very large vegetal cells and small, irregular shaped animal cells. There is a conspicuous, translucent blastocoel in the late blastula, and during gastrulation this structure is displayed forward by the internal migration of cells. Except for slight differences in proportions, the gastrula and neurula stages resemble the typical anuran pattern. Circulation (stage 20) begins when large vitelline veins develop on the yolk sac and direct the return of blood flow to the heart.
At hatching, the tadpole has a large yolk sac, little skin pigmentation, and no gills. Mouthparts and opercular coverings of the branchial arches develop slowly. Hind limb buds develop at the base of the tail, but they are soon concealed as a skin membrane develops and covers these structures.
The reproductive strategy for this primitive and highly aquatic frog is unusual: there is a small number of large eggs that develop slowly and produce tadpoles that continue this slow developmental process.