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Many studies have focused on the effects of anthropogenic habitat alterations on animals, but little attention has been given to the effects of natural changes in habitat. The purpose of our study was to examine the effects of flooding caused by Beaver (Castor canadensis) dams on the spatial ecology of the federally endangered Spotted Turtle (Clemmys guttata), in a bog in Ontario that was historically drained for peat extraction. We hypothesized that home range sizes and daily distances traveled would be greater after flooding and that habitat selection would change because turtles would exploit the increase in aquatic habitats post-flooding. Using 12 years of mark–recapture data, radio telemetry, and GIS software, we compared movements and habitat selection before and after flooding. Distances traveled and home range sizes were larger post-flood compared to pre-flood conditions, indicating that turtles were opportunistically exploring the new aquatic habitat. During pre-flooding, turtles primarily selected the drainage ditches created to facilitate peat extraction; these were the only aquatic habitat available. After flooding, there was a strong preference for newly flooded areas and drainage ditches, showing that turtles exploited the increase in available aquatic habitat. Our findings indicate that natural habitat alteration resulting from Beaver dam flooding may be beneficial for Spotted Turtles, although observations also suggest that nesting habitat may be limited due to the flooding, and further research is needed to determine the effect of the flooding on recruitment into the population.
Northern Cricket Frogs, Acris crepitans, are experiencing population declines throughout their range for unknown reasons. Habitat alteration is one potential explanation, so evaluating habitat use and movement of Cricket Frogs could be valuable to protect and manage this species. To understand how altered landscapes influence Cricket Frog movements, we initiated a study at a golf course to assess the dispersal of adults on a variety of terrestrial habitat types (mown grass, unmown grass, or the ecotone between mown and unmown grass) released at different distances from a single pond (10, 20, or 40 m). We monitored movements of adult male frogs by marking individuals with fluorescent powder. Distance from the pond did not appear to affect movement or orientation toward the pond. However, Cricket Frog movement was significantly affected by habitat type. Cricket Frogs produced longer paths in unmown grass and were more likely to orient toward the pond than frogs released at the ecotone, which may be beneficial during dispersal events. Frogs released in both unmown and mown grass moved in straighter paths than frogs released at the ecotone between these habitats, suggesting that, when given the choice, both habitat types are used to potentially optimize travel, foraging, and/or avoiding predation. Our research suggests that while managed green spaces may provide suitable habitat for connecting pond-breeding amphibians, habitat with more structure (i.e., unmown grass) may offer Cricket Frogs the greatest benefits.
We describe the diet composition of six species of dipsadines (Sibon longifrenis, S. argus, S. annulatus, S. nebulatus, Dipsas nicholsi, Dipsas sp.) from two montane forest sites in central Panama. Between 2005 and 2007 we captured 473 individual snakes, of which 305 contained no prey and two contained gut contents. Of the 166 fecal samples collected, 41 had no identifiable prey and 125 contained identifiable prey. We analyzed fecal samples and found that dipsadines at our study sites feed on mollusks, annelids, and amphibian eggs. None of the six species examined feed exclusively on mollusks, although most do feed on a variety of soft-bodied prey. Dipsas feeds extensively on earthworms, S. annulatus feeds on mollusks and earthworms, and S. longifrenis and S. argus feed heavily on amphibian eggs when available.
Herbivory is generally thought to be restricted to reptiles with large body sizes that live in warm climates. We show that Liolaemus poecilochromus is primarily herbivorous (>80% plants in diet) even as juveniles, making them the smallest herbivorous reptile known. We detected relatively few differences in diet between the sexes, despite male-biased sexual dimorphism in head and body size. Adults consumed more mites and flowers than juveniles, and we detected a weak ontogenetic shift from omnivory to herbivory that is attributable to the lower volumetric consumption of plants by juvenile males. We discuss the abiotic and biotic conditions that likely selected for herbivory in this and other small-bodied, high-elevation Liolaemus.
Herbivoría en general se cree que se limita a los reptiles con cuerpos grandes que viven en climas cálidos. Mostramos que Liolaemus poecilochromus es principalmente herbívora (>80% de plantas en la dieta) incluso los juveniles, convirtiéndolo por esto en el reptil herbívoro más pequeño conocido. Asimismo, detectamos pocas diferencias en la dieta entre los sexos, a pesar del dimorfismo sexual a favor de los machos en el tamaño de la cabeza y el cuerpo. Los adultos consumen más ácaros y flores que los juveniles, por otro lado se detectó un cambio ontogenético débil de omnivoria a herbivoría en los machos juveniles, debido a su bajo consumo de plantas. Discutimos las condiciones abióticas y bióticas que probablemente favorecieron la herbivoría en este y otros Liolaemus de cuerpo pequeño y alta elevación.
Behavior of settlement-stage (10–17 mm SL) larvae of five chaetodontid species (Chaetodon auriga, C. aureofasciatus, C. rainfordi, C. plebeius, and Chelmon rostratus) captured in light traps was investigated in open water and over coral reefs at Lizard Island, Great Barrier Reef. Average swimming speeds of all species in open water (18–26 cm s−1) were greater than average current speeds; larvae swam several meters deeper off the deeper east side of the island than off the west side, and most larvae swam directionally. Near coral reefs, about 37% of larvae swam offshore at speeds that were frequently greater than those at which they swam toward or over reefs. After a mean of 5 min, 40% of larvae reaching reefs swam away offshore, many after harassment by resident fishes. About 5% were eaten; the rest settled in a mean of 2 min. Chaetodon plebeius never settled. Non-predatory resident fishes strongly influenced the distribution of butterflyfish settlers. The three species that settled in usable numbers had species-specific settlement depths and substratum, primarily live corals. Comparing these results to studies on larger juveniles shows that individuals become increasingly selective about habitat (usually coral taxa) as they grow. Larval settlement behavior of chaetodontids is more similar to that of pomacentrids than that of lutjanids or serranids, but some features are shared by all families.
We investigated the annual nesting ecology of a population of Desert Tortoises (Gopherus agassizii) inhabiting a utility-scale renewable energy (USRE) facility in southern California and compared our results with populations inhabiting relatively undisturbed sites. In 2000, 15 radio-tracked females produced 29 clutches, and 24 nests were monitored to examine nest-site selection, nest predation, hatching success, date of emergence of hatchlings, and hatchling mass and carapace length. Overall, the nesting ecology of the population inhabiting the USRE facility was very similar to other populations of Desert Tortoises inhabiting relatively undisturbed habitats. Oviposition occurred from 12 May to 8 July, which was similar to other sites. Nest depths (11.1 cm), nest predation (12%), hatchling emergence date (7 August and 29 September), and hatchling morphometrics (i.e., MCL: 44.5 mm; mass: 23 g) were all within ranges reported in other populations. Unlike within other populations, we observed no relationship between hatchling size and either maternal body size or egg width. We found no evidence of females selecting for a particular burrow for oviposition of eggs based on environmental or anthropogenic variables. Most nests were located in or near burrows, and nest depth was greater for nests near the entrance than those deeper in the burrow. Although this study suggests that the nesting ecology of the Desert Tortoise population we studied was not adversely affected by the USRE facility, this relationship is only correlative because our study was not a before-after-control-impact (BACI) study, which would establish a cause and effect relationship. As pointed out in a recent review, BACI studies are critically needed to address the wildlife impacts of utility-scale renewable energy development.
Ultrastructural study of oogenesis of the Scarus ferrugineus was carried out during the period of oocyte growth, particularly the changes in nuclear morphology, cytoplasmic organelles, and wall formation. Materials produced in the nucleus and transported to the cytoplasm known as nuage were observed in the oogonia and primary oocytes at premeiotic and perinucleolar stages. This material gives rise to germ plasma in the growing oocytes. In the perinucleolar oocyte, the cytoplasm appears loaded with free ribosomes and dense bodies. Short strands of endoplasmic reticulum (ER), perinuclear mitochondrial ring, and a simple layer of flattened granulosa cells were also detected. Protrusion of short buds from oocyte and granulose surfaces to the perioocyte space was clearly detected in the oocyte. From the early vitellogenic stage (yolk vesicle oocyte) the vitelline envelope was observed as a single electron-dense mesh pattern layer, becoming thicker during the vitellogenic stage. The granulosa cells (GCs) become organelle-rich with elongate mitochondria, free ribosomes, dilated tubular RER, and a Golgi system. Both GCs and thecal cells (TCs) show ultrastructural steroidogenic features, suggesting their primary roles in the production and secretion of steroid hormones at this stage of ovarian development. Remarkable ultrastructural changes were shown in vitellogenic oocytes including increase in RER, proliferation of mitochondria, and protrusion of long microvilli from oocyte and granulosa cells into pore canals of the vitelline membrane. The microvilli withdraw by the end of yolk deposition and the granulosa cells dissociate in fully grown oocytes. In atretic oocytes, the vitelline membrane homogenized and fragmented. Also, GCs, and maybe TCs, proliferated, hypertrophied, and phagocytosed the oocyte remnants forming temporary structure. Degeneration of previtellogenic oocytes prior to sex change was described and discussed.
Sex ratio, fecundity, gonosomatic indices (GSI), and time of spawning were examined for the Turquoise Darter (Etheostoma inscriptum) from January through June 2009. Approximately 30 specimens per sample were captured and examined in roughly three-week intervals. Additional sex ratio data were collected on 314 specimens from 3 to 13 March 2009. Sex ratio favored females 1.8∶1. Male weight and length were both found to be significantly greater than those of females. Peak GSI for males was the 2 April sample (1.1%), declining considerably by 19 June (0.4%). Peak GSI for females occurred 23 April (12.83%) followed by a decline through May, and continued to decline through June, when spawning appeared to end. Fecundity analysis showed a continuum of ova maturation during the spawning period with annual fecundity estimates ranging from 122 to 235 ova/yr. GSI and fecundity analysis together support that spawning in E. inscriptum initiates near mid April and continues until June in a series of multiple spawns. These previously unknown life history aspects of E. inscriptum are a valuable asset in management applications for the species.
Ctenocheirodon pristis, a new genus and species of cheirodontine fish from South America is described. The new genus possesses derived ventral procurrent caudal-fin rays and anal-fin rays that support its placement among characids of the tribe Cheirodontini. The new genus and species is diagnosed from the other members of the tribe by the shape of ventral procurrent caudal-fin rays and anal-fin rays.
Ctenocheirodon pristis, um novo gênero e espécie de Cheirodontinae da América do Sul é descrito. O novo gênero possui raios procurrentes ventrais da nadadeira caudal e raios da nadadeira anal derivados, que suportam sua alocação entre os caracídeos da tribo Cheirodontini. O novo gênero e espécie são diagnosticados dos demais táxons da tribo pelo formato dos raios procurrentes ventrais da nadadeira caudal e raios da nadadeira anal.
A new species of clingfish belonging to the genus Derilissus is described from a deep coral wall in the Exumas, Bahamas. The new species is distinguished from congeners by a unique pigmentation pattern and coloration, the presence of 47 total pectoral-fin rays, a strongly convex posterior margin on disk region B, and by a unique arrangement of papillae on disk region C. The new species is characterized by bright orangish-red coloration on the flank, a yellow head, and a prominent black oval marking on the caudal peduncle. Like other members of the genus, the new species appears to be restricted to the mesophotic zone, and was collected at 286 fsw.
Two new species of snailfishes are described: Careproctus lycopersicus from the Bering Sea and Careproctus kamikawai from the eastern North Pacific Ocean off southern California. Careproctus lycopersicus was collected at depths of 304 to 1096 m and C. kamikawai at 468 to 1399 m. Both species are most similar to C. ovigerus, from which they are easily distinguished by trilobed teeth in broad bands on both upper and lower jaws, as opposed to the strong simple canine teeth in narrow rows of C. ovigerus. The new species have robust bodies, large pelvic discs, and counts of meristic characters, including dorsal-fin rays 42–45, anal-fin rays 34–38, pectoral-fin rays 33–38, and total vertebrae 45–50, which distinguish them from all other species. Careproctus lycopersicus is distinguished from C. kamikawai by its pale to dusky (vs. black) peritoneum, deeper caudal-fin base, and a longer and wider pelvic disc. In addition, the pelvic disc, anus, and anal-fin origin are all more posteriorly placed on the body in C. lycopersicus. The similar and rare species Careproctus ovigerus is redescribed based on all known material.
Hisonotus bockmanni, new species, is described based on specimens collected in a sandbank in the Rio Cururu, a tributary to the Rio Teles Pires, one of the rivers forming the Rio Tapajós in the Amazon Basin. The new taxon is distinguished from its congeners by a unique color pattern, whose most striking features are: two elliptical white spots, anterior to nostrils; predorsal region darkly pigmented with five unpigmented spots arranged as anteriorly pointed chevron; and a rostrocaudally elongate cross along most of the caudal peduncle. The placement of the new species in Hisonotus as well as its possible affinities within that genus are discussed in light of the current knowledge of the phylogenetic relationships among the Hypoptopomatinae.
Hisonotus bockmanni, nova espécie, é descrita com base em espécimes coletados em um banco de areia no Rio Cururu, afluente do Rio Teles Pires, um dos formadores do Rio Tapajós na Bacia Amazônica. O novo táxon é distinguido de seus congêneres por possuir um padrão de coloração único cujas características mais marcantes são: duas manchas elípticas brancas, anteriores às narinas; região pré-dorsal escura com cinco pontos não pigmentados dispostos como uma bifurcação apontada anteriormente; e uma cruz alongada rostrocaudalmente ao longo da maior parte do pedúnculo caudal. O posicionamento da nova espécie em Hisonotus, assim como suas possíveis relações dentro do gênero, é discutido com base no conhecimento atual das relações filogenéticas entre os Hypoptopomatinae.
Smith's small-headed sea snake, Hydrophis parviceps, was originally described in 1935 from a single type specimen collected in southern Vietnam. Since this time there has been only one further record for the species—a specimen collected near the type locality in 1960 that has since been lost. Through field surveys in southern Vietnam in 2001, we obtained three additional specimens of this poorly known sea snake from fisheries bycatch. In the current paper, we present morphological and molecular data for the three new specimens and the holotype, and redescribe H. parviceps based on data synthesized for all five specimens known to date. We also discuss the conservation status of the species based on its vulnerability to fisheries bycatch mortality and seemingly low abundance within a very restricted geographic distribution.
Apteronotus lindalvae, a new species of sexually dimorphic electric knifefish, is described from the Rio Uatumã, Amazon basin, Brazil. This is the first species of Apteronotus, outside the Apteronotus albifrons complex, known to inhabit rapids and waterfalls of Amazonian Rivers, being reophilic. The new species is distinguished from all congeners by a unique feature, the presence of an unpigmented dorsal stripe extending from the tip of the chin to beyond the posterior border of the eye, but never extending as far back as the branchial opening. It is also distinguished by the total number of anal-fin rays and the length of the caudal fin. The description of A. lindalvae increases to 19 the number of species in Apteronotus.
Apteronotus lindalvae, uma nova espécie sexualmente dimórfica de peixe elétrico é descrita do rio Uatumã, na bacia Amazônica, Brasil. Apteronotus lindalvae é a primeira espécie de Apteronotus encontrada em corredeiras e cachoeiras dos rios da Amazônia, além destes que fazem parte do complexo Apteronotus albifrons, a ser considerada de hábito reofílico. A espécie nova é diferenciada de todos os congêneres por uma característica exclusiva, a presença de uma faixa clara dorsal que se estende da ponta do focinho até a borda posterior do olho, mas nunca se extendendo além da abertura branquial. Assim como pode ser diferenciada pelo número total de raios da nadadeira anal, e o comprimento da nadadeira caudal. A descrição de A. lindalvae eleva para 19 o número de espécies em Apteronotus.
Questions remain about the taxonomy and distribution of geographically widespread species in the circumtropical gobiid genus Awaous. Previous work that placed two species in synonymy on the basis of morphological characteristics effectively redefined the range of Awaous guamensis to include distant locations from Hawai'i and Guam to the islands of South-East Melanesia. Here we evaluate the synonymy of A. guamensis and A. stamineus through phylogeographic analysis of mitochondrial DNA sequence variation and morphological comparisons of Hawai'i and Guam populations. Phylogenetic assessments show clear separation of molecular characteristics, and morphological analyses illustrate statistically significant phenotypic differences indicating that the populations represent distinct evolutionary lineages. Based upon genetic, morphological, and geographic distributional differences, we recommend that Hawaiian populations be recognized as a distinct species, and reversion to the previous nomenclature of Awaous stamineus.
We examined mitochondrial DNA sequence variation among populations of the Ouachita Map turtle (Graptemys ouachitensis ouachitensis), an aquatic species distributed throughout the Mississippi River drainage. We sequenced a 620 base-pair segment of the mitochondrial control region for 65 individuals collected throughout this turtle's range, identifying 18 haplotypes that form two minimally divergent groups. These haplotype groups exhibit substantial range overlap. A presumably disjunct population from the Scioto River in Ohio is represented by both haplotypes groups. The limited genetic differentiation observed suggests that the broad geographic range of haplotypes of G. o. ouachitensis reflects considerable dispersal from two Pleistocene glacial refugia, possibly Mississippi River and Teays River.
Two topics of great importance to conservation biologists and managers are the impact of habitat degradation on species' distributions and the effects of invasive species on the decline of other species. I evaluate the interaction of these threats by comparing the impact of a native invasive amphibian species on a formerly allotopic amphibian species in disturbed versus undisturbed habitat. Fowler's Toad (Anaxyrus fowleri) historically thrived in a range of habitats including urban and suburban areas in the mid-twentieth century, but has recently undergone a range contraction concurrent with the spread of the Coastal Plain Toad (Incilius nebulifer) into recently disturbed habitat. Contemporary surveys of historical collection sites obtained from museum records of vouchered specimens were used to document changes in the distribution of both species over the past half-century. Temporal changes in habitat disturbance at collection sites were detected by comparing historical aerial photographs with current remote sensing data. Analysis of species' distribution in different disturbance levels showed that A. fowleri is unaffected by disturbance in areas where I. nebulifer is absent, but at sites where the species are sympatric the distribution of A. fowleri in degraded habitat contracted while the expansion of I. nebulifer increased substantially. This study demonstrates that anthropogenic habitat alteration can facilitate dispersal and colonization by an invasive species, resulting in the significant decline of a native species that is otherwise tolerant of disturbance.
The conversion of the Northern Great Plains of North America to a landscape favoring agricultural commodity production has negatively impacted wildlife habitats. To offset impacts, conservation programs have been implemented by the U.S. Department of Agriculture and other agencies to restore grassland and wetland habitat components. To evaluate effects of these efforts on anuran habitats, we used call survey data and environmental data in ecological niche factor analyses implemented through the program Biomapper to quantify habitat suitability for five anuran species within a 196 km2 study area. Our amphibian call surveys identified Northern Leopard Frogs (Lithobates pipiens), Wood Frogs (Lithobates sylvaticus), Boreal Chorus Frogs (Pseudacris maculata), Great Plains Toads (Anaxyrus cognatus), and Woodhouse's Toads (Anaxyrus woodhousii) occurring within the study area. Habitat suitability maps developed for each species revealed differing patterns of suitable habitat among species. The most significant findings of our mapping effort were 1) the influence of deep-water overwintering wetlands on suitable habitat for all species encountered except the Boreal Chorus Frog; 2) the lack of overlap between areas of core habitat for both the Northern Leopard Frog and Wood Frog compared to the core habitat for both toad species; and 3) the importance of conservation programs in providing grassland components of Northern Leopard Frog and Wood Frog habitat. The differences in habitats suitable for the five species we studied in the Northern Great Plains, i.e., their ecological niches, highlight the importance of utilizing an ecosystem based approach that considers the varying needs of multiple species in the development of amphibian conservation and management plans.
Linnet Lake (Waterton Lakes National Park, Alberta) is the breeding site of a population of Long-toed Salamanders (Ambystoma macrodactylum) that has decreased dramatically over the last 15 years, partially due to vehicle-caused mortality occurring on an adjacent road. In May 2008, Parks Canada installed four amphibian tunnels under this road. We installed drift fences to direct salamanders toward tunnel entrances and monitored tunnel use with pitfall traps in 2008 and 2009. We used logistic regressions and Akaike's Information Criterion (AIC) to determine if probability of tunnel use differed among individual salamanders. Salamander road mortality decreased from 10% of the population to <2% following installation of tunnels and fences. In 2009, 104 salamanders were documented using tunnels. Salamanders were 20 times more likely to use tunnels when traveling to the breeding site than when leaving the site. Distance from tunnel entrances, sex, and body size did not have significant effects on tunnel use by salamanders. Although salamander movement was positively correlated with occurrence of precipitation, this relationship was much stronger when salamanders were leaving the breeding site. Variation in use between the four tunnels was positively correlated with soil moisture of surrounding habitat. Continued monitoring will be needed to determine if tunnel use by Long-toed Salamanders increases through time, and if decreased road mortality translates into population gains.
Organisms that are distributed across spatial climate gradients often exhibit adaptive local variations in morphological and physiological traits, but to what extent such gradients shape evolutionary responses is still unclear. Given the strong natural contrast in latitudinal temperature gradients between the North-American Pacific and Atlantic coast, we asked how increases in vertebral number (VN, known as Jordan's Rule) with latitude would differ between Pacific (Atherinops affinis) and Atlantic Silversides (Menidia menidia), two ecologically equivalent and taxonomically similar fishes with similar latitudinal distributions. VN was determined from radiographs of wild-caught adults (genetic environmental differences) and its genetic basis confirmed by rearing offspring in common garden experiments. Compared to published data on VN variation in M. menidia (a mean increase of 7.0 vertebrae from 32 to 46°N, VN slope = 0.42 lat−1), the latitudinal VN increase in Pacific Silversides was approximately half as strong (a mean increase of 3.3 vertebrae from 28 to 43°N, VN slope = 0.23 lat−1). This mimicked the strong Atlantic (1.11°C lat−1) versus weak Pacific latitudinal gradient (0.40°C lat−1) in median annual sea surface temperature (SST). Importantly, the relationship of VN to SST was not significantly different between the two species (average slope = −0.39 vertebrae °C−1), thus suggesting a common thermal dependency of VN in silverside fishes. Our findings provide novel support for the hypothesis that temperature gradients are the ultimate cause of Jordan's Rule, even though its exact adaptive significance remains speculative. A second investigated trait, the mode of sex determination in Atlantic versus Pacific Silversides, revealed patterns that were inconsistent with our expectation: M. menidia displays temperature-dependent sex determination (TSD) at low latitudes, where growing seasons are long or unconstrained, but also a gradual shift to genetic sex determination (GSD) with increasing latitude due to more and more curtailed growing seasons. Sex ratios in A. affinis, on the other hand, were independent of latitude and rearing temperature (indicating GSD), even though growing seasons are thermally unconstrained across most of the geographical distribution of A. affinis. This suggests that additional factors (e.g., longevity) play an important role in shaping the mode of sex determination in silverside fishes.