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Walter G. Joyce - One of the best experts on this subject based on the ideXlab platform.

  • macrobaenidae testudines eucryptodira from the late paleocene clarkforkian of montana and the taxonomic treatment of Clemmys backmani
    Bulletin of The Peabody Museum of Natural History, 2010
    Co-Authors: Donald B. Brinkman, Michael Densmore, Walter G. Joyce
    Abstract:

    Two partial “macrobaenid” shells are described from a single Late Paleocene (Clarkforkian 1) quarry at Burns Mine near Washoe, Carbon County, Montana, USA, and are referred to “Clemmys” backmani, a taxon typified in the Paleocene Ravenscrag Formation of Saskatchewan, Canada. Though tentative, morphological, temporal and spatial arguments highlight similarities between “Clemmys” backmani and the Campanian taxon Judithemys sukhanovi, and we therefore suggest the new combination Judithemys backmani. Judithemys sukhanovi and Judithemys backmani both originate from the eastern margins of the western landmass Laramidia and exhibit a pronounced ridge along the visceral side of the first costal and C-shaped bridge peripherals into which the flat thoracic ribs insert superficially, characters that must be interpreted as symplesiomorphies. By contrast, the coeval taxon Osteopygis emarginatus originates from the eastern shores of the eastern landmass Appalachia, lacks the visceral ridge of the first costal, and possesses massive, triangular peripherals into which the peglike thoracic ribs insert deeply.

  • “Macrobaenidae” (Testudines: Eucryptodira) from the Late Paleocene (Clarkforkian) of Montana and the Taxonomic Treatment of “Clemmys” backmani
    Bulletin of the Peabody Museum of Natural History, 2010
    Co-Authors: Donald B. Brinkman, Michael Densmore, Walter G. Joyce
    Abstract:

    Two partial “macrobaenid” shells are described from a single Late Paleocene (Clarkforkian 1) quarry at Burns Mine near Washoe, Carbon County, Montana, USA, and are referred to “Clemmys” backmani, a taxon typified in the Paleocene Ravenscrag Formation of Saskatchewan, Canada. Though tentative, morphological, temporal and spatial arguments highlight similarities between “Clemmys” backmani and the Campanian taxon Judithemys sukhanovi, and we therefore suggest the new combination Judithemys backmani. Judithemys sukhanovi and Judithemys backmani both originate from the eastern margins of the western landmass Laramidia and exhibit a pronounced ridge along the visceral side of the first costal and C-shaped bridge peripherals into which the flat thoracic ribs insert superficially, characters that must be interpreted as symplesiomorphies. By contrast, the coeval taxon Osteopygis emarginatus originates from the eastern shores of the eastern landmass Appalachia, lacks the visceral ridge of the first costal, and possesses massive, triangular peripherals into which the peglike thoracic ribs insert deeply.

Jacqueline D. Litzgus - One of the best experts on this subject based on the ideXlab platform.

  • Geographic Variation in Somatic Growth Rate of Wood Turtles (Glyptemys insculpta)
    Copeia, 2018
    Co-Authors: Kelsey A. Marchand, Geoffrey N. Hughes, Jacqueline D. Litzgus
    Abstract:

    Life history traits, such as body size and age at maturity, display intraspecific variation across a species' geographic range. Previous studies that examined body size variation among conspecific populations of turtles found that body size generally increases with increasing latitude, with the exception of Wood Turtles (Glyptemys insculpta) and Spotted Turtles (Clemmys guttata), which follow a non-linear relationship with larger body sizes at the two range extremes. Similarly, growth rates are influenced by climatic variables and should display geographic patterns reflective of different environments. The objectives of our study were to a) quantify somatic growth in a northern population of Wood Turtles, and b) determine if the observed geographic variation in body size was the result of interpopulation variation in somatic growth rates. In the northern population, as turtles approached maturity, somatic growth increments varied between the sexes such that on average males grew to larger mean carapace le...

  • Habitat Selection and Movement Patterns of Spotted Turtles (Clemmys guttata): Effects of Spatial and Temporal Scales of Analyses
    Copeia, 2010
    Co-Authors: Megan L. Rasmussen, Jacqueline D. Litzgus
    Abstract:

    Abstract Habitat selection is important for a species' survival, and its identification represents a crucial component in the development of conservation strategies. Habitat selection occurs when habitats are used disproportionately to their availability, and what constitutes available habitat will depend on the biology of the species under investigation. Habitat selection and movement patterns of Spotted Turtles (Clemmys guttata) in a population near Lake Huron, Ontario, were studied over two consecutive years using radio telemetry. Selection was assessed at two spatial scales (second order, home range from population range; and third order, locations from home range) using compositional analyses. Spotted Turtles shift macrohabitat use throughout the annual cycle, therefore seasonal habitat selection was also analyzed. Selection occurred at both scales tested, and the ranking of preferred habitats differed based on the scale of analysis. Selection differed across seasons (emergence, nesting, post-nesting...

  • Stochastic and spatially explicit population viability analyses for an endangered freshwater turtle, Clemmys guttata.
    Canadian Journal of Zoology, 2009
    Co-Authors: J. J. Enneson, Jacqueline D. Litzgus
    Abstract:

    Over two thirds of the world’s turtle species are in decline as a result of habitat destruction and harvesting. Quantitative methods for predicting the risk of extinction of turtle populations are essential for status assessments and recovery planning. Spotted turtles (Clemmys guttata (Schneider, 1792)) are considered vulnerable internationally, and endangered in Canada. We used population viability analysis to assess the risk of extirpation of a Georgian Bay, Ontario, population that has been under study since 1977 and of nine Ontario populations for which population size is known, and to examine the effects of dispersal between breeding ponds on population persistence. A simple stochastic model for the Georgian Bay population projected a 60% probability of extirpation in 100 years. A metapopulation model for the same study area projected an 18% probability of extirpation within 100 years, suggesting that dispersal between breeding ponds is important for population persistence. Spotted turtles at this re...

  • Reproductive Output Depends on Body Condition in Spotted Turtles (Clemmys Guttata)
    Copeia, 2008
    Co-Authors: Jacqueline D. Litzgus, Frances Bolton, Albrecht I. Schulte-hostedde
    Abstract:

    The body condition of an animal reflects its energetic state such that an animal in good condition has greater energy reserves than one that is in poor condition. Body condition in turn should be positively correlated with fitness because energetic reserves limit the amount of energy that can be allocated to reproduction. Using Spotted Turtles (Clemmys guttata) as a model system, and three years of field data from a South Carolina, USA population, we tested the prediction that reproductive output increases with maternal body condition. The effect of body condition on the reproductive output of female turtles was examined at three temporal scales (among clutches, among nesting seasons, and among females) using several variables including clutch frequency, clutch size, and multiple measures of egg size. We predicted that females in good condition will have a higher clutch frequency than those in poor condition; that females in good condition will have larger clutch sizes than those in poor condition; and that females in good condition will have larger eggs than those in poor condition. Among clutches and nesting seasons, we found no relationship between female body condition and reproductive output. Among females over the entirety of the three-year study, we found a positive relationship between body condition and clutch mass and egg size. In addition, females in poor condition and females in good condition both produced larger clutch sizes than females in intermediate condition. Our findings suggest that within a given reproductive bout and within a given reproductive season, energy reserves do not affect immediate reproductive investment. However, over the longer-term, females in good condition have greater reproductive output, which supports the idea of a bet-hedging life history strategy in turtles.

  • GEOGRAPHIC VARIATION IN REPRODUCTION IN A FRESHWATER TURTLE (Clemmys GUTTATA)
    Herpetologica, 2006
    Co-Authors: Jacqueline D. Litzgus, Timothy A. Mousseau
    Abstract:

    We examined reproduction over 3 yr using radio telemetry and X-rays in a South Carolina population of spotted turtles (Clemmys guttata). Spring courtship (March-April) coincided with aggregations of turtles; however, a second peak in courtship in the fall (September-October) did not coincide with such aggregations. Over 75% of the radio-tagged females were gravid in each year of the study. The nesting season lasted approximately two months (mid-May through mid-July). Nesting was primarily nocturnal, and most nests (17/21, 81%) were made in the woody debris of decaying logs and stumps. Incubation time (mean 5 79 d) decreased as nest temperature increased. Clutch size was not correlated to maternal body size, and we found no evidence for a tradeoff between clutch size and egg size. However, all measures of egg size and most measures of hatchling size were independent of maternal body size. We also compared reproduction among three widely separated populations of spotted turtles. Clutch size varied with latitude: clutch size was largest in the north (Ontario, mean 5 5.3 eggs), mid-sized in the central population (Pennsylvania, mean 5 3.9), and smallest in the south (South Carolina, mean 5 2.8). Variation in reproductive output among populations was attributable to both variation in number of eggs and to egg size. Most of this variation in clutch size and egg size was explained by differences in body size of females among populations. Because the spotted turtle is considered to be a Species at Risk throughout its range, the data provided in the current study will be useful in conservation planning and for directing future research on the reproductive ecology of freshwater turtles.

Elizabeth M. Gray - One of the best experts on this subject based on the ideXlab platform.

  • DNA Fingerprinting Reveals a Lack of Genetic Variation in Northern Populations of the Western Pond Turtle (Clemmys marmorata)
    Conservation Biology, 1995
    Co-Authors: Elizabeth M. Gray
    Abstract:

    :I used DNA fingerprinting to provide the first analysis of the genetic composition of western pond turtle (Clemmys marmorata( populations in Washington, Oregon, and California. Populations of the western pond turtle in Washington and northern Oregon are rapidly approaching extinction. Genetic similarity within the largest northern populations, which are located inland, is high. An analysis of population substructure (Fst) revealed significant genetic divergence between inland populations, indicating a lack of dispersal and gene flow between sites. In contrast, northern coastal sites are not genetically distinct, but there are few if any viable populations remaining in this region. Genetic variability within southern California populations is a great deal higher than in northern inland sites. Similarly, a low Fst value indicated a lack of genetic differentiation between southern sites. An inter-regional analysis of population substructure (Fst= 0.24) revealed a significant degree of genetic divergence between geographical regions throughout the range. In addition, an estimate of western pond turtle phylogeny showed a genetic break in the species between northern and southern populations. Both population subdivision and phylogenetic analyses suggest a lack of appreciable gene flow between geographical regions for a considerable period of time. Genetic analyses support traditional subdivision based solely on the morphological variation of Clemmys marmorata into two subspecies: northern Clemmys marmorata marmorata and southern Clemmys marmorata pallida. Recovery of dwindling northern populations must combine demographic and genetic considerations. A first step should be to preserve local gene pools while augmenting population numbers, with the goal of preventing the extinction of this genetically and morphologically distinct subspecies. La falta de variacion genetica en poblaciones nortenas de la tortuga de agua dulce del oeste (Clemmys marmorata) Resumen: En este estudio se utilizo analisis de “hellas digitales” de ADN para presentar el primer analisis sobre composicion genetica en poblaciones de la tortuga de agua dulce del oeste (Clemmys marmorata) en Washington, Oregon y California. Las poblaciones de esta tortuga en los estados de Washington y Oregon estan al borde de la extincion. La similitud genetica dentro de las poblaciones nortenas mas grandes, que estan localizades tierra adentro, es alta. Un analisis de a subestructura de los poblaciones (Fst) muestra una divergencia genetica significativa entre las poblaciones del interior, lo que indica una ausencia de dispersion y flujo genico entre ellas. En contraste, los sitios costeros del norte no son geneticamente distintos, sin embargo, en esta region las poblaciones viables que quedan son pocas o inexistentes. Las poblaciones del sur de California presentan una variabilidad genetica mucho mayor que las poblaciones nortenas del interior. Para las localidades del sur se obtuvieron valores bajos de Fst, lo que indica que no hay diferenciacion genetica entre estas poblaciones. Tambien se realizo un analisis inter-regional de subestructura poblacional, y se encontro una divergenica genetica significativa entre las regiones geograficas a lo largo del rango estudiado (Fst= 0.24). Adicionalmente, una estimacion de la filogenia de C. marmorata mostro una discontinuidad genetica entre las poblaciones del norte y del sur. Tanto el analisis de subdivision poblacional como el analisis filogenetico sugieren que no ha habido flujo genico apreciable entre las regiones geograficas desde hace bastante tiempo. El analisis genetico apoya la subdivision tradicional, que se basa unicamente en la variacion morfologica de Clemmys marmorata, y la separa en dos subespecies: Clemmys marmorata marmorata en el norte y Clemmys marmorata pallida en el sur. Para la recuperacion de las poblaciones menguantes del norte se tendran que considerar tanto los aspectos geograficos como los geneticos. Un primer paso seria preservar los bagajes genicos locales a la vez que incrementar dichas poblaciones, con el objetivo de prevenir la extincion de estas subespecies que son diferentes tanto morfologico como geneticamente.

Donald B. Brinkman - One of the best experts on this subject based on the ideXlab platform.

  • macrobaenidae testudines eucryptodira from the late paleocene clarkforkian of montana and the taxonomic treatment of Clemmys backmani
    Bulletin of The Peabody Museum of Natural History, 2010
    Co-Authors: Donald B. Brinkman, Michael Densmore, Walter G. Joyce
    Abstract:

    Two partial “macrobaenid” shells are described from a single Late Paleocene (Clarkforkian 1) quarry at Burns Mine near Washoe, Carbon County, Montana, USA, and are referred to “Clemmys” backmani, a taxon typified in the Paleocene Ravenscrag Formation of Saskatchewan, Canada. Though tentative, morphological, temporal and spatial arguments highlight similarities between “Clemmys” backmani and the Campanian taxon Judithemys sukhanovi, and we therefore suggest the new combination Judithemys backmani. Judithemys sukhanovi and Judithemys backmani both originate from the eastern margins of the western landmass Laramidia and exhibit a pronounced ridge along the visceral side of the first costal and C-shaped bridge peripherals into which the flat thoracic ribs insert superficially, characters that must be interpreted as symplesiomorphies. By contrast, the coeval taxon Osteopygis emarginatus originates from the eastern shores of the eastern landmass Appalachia, lacks the visceral ridge of the first costal, and possesses massive, triangular peripherals into which the peglike thoracic ribs insert deeply.

  • “Macrobaenidae” (Testudines: Eucryptodira) from the Late Paleocene (Clarkforkian) of Montana and the Taxonomic Treatment of “Clemmys” backmani
    Bulletin of the Peabody Museum of Natural History, 2010
    Co-Authors: Donald B. Brinkman, Michael Densmore, Walter G. Joyce
    Abstract:

    Two partial “macrobaenid” shells are described from a single Late Paleocene (Clarkforkian 1) quarry at Burns Mine near Washoe, Carbon County, Montana, USA, and are referred to “Clemmys” backmani, a taxon typified in the Paleocene Ravenscrag Formation of Saskatchewan, Canada. Though tentative, morphological, temporal and spatial arguments highlight similarities between “Clemmys” backmani and the Campanian taxon Judithemys sukhanovi, and we therefore suggest the new combination Judithemys backmani. Judithemys sukhanovi and Judithemys backmani both originate from the eastern margins of the western landmass Laramidia and exhibit a pronounced ridge along the visceral side of the first costal and C-shaped bridge peripherals into which the flat thoracic ribs insert superficially, characters that must be interpreted as symplesiomorphies. By contrast, the coeval taxon Osteopygis emarginatus originates from the eastern shores of the eastern landmass Appalachia, lacks the visceral ridge of the first costal, and possesses massive, triangular peripherals into which the peglike thoracic ribs insert deeply.

Barbour, Roger W. - One of the best experts on this subject based on the ideXlab platform.