61 research outputs found
Importance of source structure on complex organics emission II. Can disks explain lack of methanol emission from some low-mass protostars?
No full textSome protostellar systems show little or no millimetre line emission of
complex organics. This can be interpreted as a low abundance of these
molecules, alternatively they could be present in the system but are not seen
in the gas. The goal is to investigate the latter hypothesis for methanol. We
will attempt to answer the question: Does the presence of a disk and optically
thick dust reduce methanol emission even if methanol is abundant in the ices
and gas? Using the radiative transfer code RADMC-3D, methanol emission lines
from an envelope-only model and an envelope-plus-disk model are calculated and
compared with each other and the observations. Methanol emission from the
envelope-only model is always stronger than from the envelope-plus-disk model
by at least a factor 2 as long as the disk radius is larger than 30 au (for L=8
L). In most cases, this is due to lower temperatures and, hence, the
smaller amount of warm methanol inside the snow surface of the
envelope-plus-disk model. The intensities drop by more than an order of
magnitude for models including high mm opacity dust grains and disk radii of at
least 50 au (for L=8 L) due to continuum over-subtraction. The line
intensities from the envelope-only models overproduce the observations of
protostars with lower methanol emission even with large dust optical depth
effects. The envelope-plus-disk models can explain the bulk of the
observations. However, they can only reproduce the observations of sources with
high luminosities and low methanol emission when dust optical depth effects
especially continuum over-subtraction in the disk becomes effective. Therefore,
both the effects of disk and dust optical depth should be considered to explain
the observations. In conclusion: Absence of methanol emission does not imply
absence of methanol molecules in either gas or ice.Comment: Accepted to A&
First state record and interdiction for the Wood Slave, \u3ci\u3eHemidactylus mabouia\u3c/i\u3e (Moreau de Jonnès 1818) (Gekkonidae), in Maryland, USA.
No full textThe Wood Slave, Hemidactylus mabouia (Moreau de Jonnès 1818; Fig. 1), is indigenous to Africa south of the Sahara, with nonindigenous populations established in Cape Verde, Mexico, much of Central and South America, numerous localities in the Caribbean, perhaps Madagascar, and at least 21 counties in Florida, USA (Carranza and Arnold 2006; Kraus 2009; Krysko et al. 2011a, 2011b; Meshaka 2011; Powell and Henderson 2012). Recently, H. mabouia has successfully invaded temperate regions of southern Africa and northern peninsular Florida (Alexander and Marais 2007, Krysko and Somma 2007).
On 20 December 2012, Brian R. Grogan and Shane Forsythe collected and photographed one adult Hemidactylus mabouia found inside a furniture-moving truck at 8909 Amelung Street, Frederick, Frederick County, Maryland. This is a first state interdiction for Maryland and the northernmost record for H. mabouia in North America and the Western Hemisphere
SNAKE ASSEMBLAGE STRUCTURES AND SEASONAL ACTIVITY PATTERNS ON A MILITARY BASE IN SOUTH-CENTRAL PENNSYLVANIA:: LAND MANAGEMENT IMPLICATIONS FOR SNAKE CONSERVATION
No full textWe ascertained the assemblage structures of snakes occurring in a mixed habitat matrix of natural and disturbed habitats during 2008–2011 at Letterkenny Army Depot (LEAD), a 7200 ha U.S. Army base in south-central Pennsylvania, to understand the patterns of species abundance as they related to habitat type of managed lands. We detected eight species in 12 sites comprising natural and disturbed habitats of wetlands, forest, and thicket and open fields. The Common Gartersnake (Thamnophis sirtalis) occurred in the most sites, the Red-bellied Snake (Storeria occipitomaculata) was the rarest species in the study. Two to six species occupied each site and were distributed unevenly. Dynamics of assemblages could be explained in part by habitat and also by the presence of the North American Racer (Coluber constrictor). All species for which data were available exhibited a unimodal pattern to their seasonal activity (mostly May and June); however, seasonal activity peaks differed between sexes. Sex ratios varied among species but were consistently female–biased in the Common Gartersnake and Ring-necked Snake (Diadophis punctatus) in Pennsylvania and surrounding areas. As elsewhere in Pennsylvania and the Northeast, body sizes of adults were larger for species syntopic with the North American Racer than for species not syntopic with this potential predator. We found a degree of predictability with respect to snake assemblage dynamics among habitats at LEAD, which in turn can prove useful in resource management of this large and protected human-impacted system
Clutch Sizes in Two Populations of the Eastern Garter Snake (Thamnophis sirtalis) in Pennsylvania
No full textSpreading Holiday Spirit and Northwestern Salamanders, \u3ci\u3eAmbystoma gracile\u3c/i\u3e (Baird 1859) (Caudata: Ambystomatidae), Across the USA
No full textIntroduced species of amphibians and reptiles are of growing conservation concern (Bury and Luckenbach 1976; Krysko et al. 2011; Meshaka 2011). Unintentional introductions result largely from individuals escaping from enclosures or hitch-hiking in cargo or on vehicles, whereas intentional introductions occur primarily because a species is perceived to be of value to humans or from deliberately releasing sick or unwanted animals, including pets (Kraus 2009; Krysko et al. 2011). In Florida, most known introductions are directly related to the pet trade, but about 12% are related to the cargo pathway (Krysko et al. 2011). In this paper, we report the introduction of the Northwestern Salamander, Ambystoma gracile (Baird 1859), in Florida from Broward County, and in California from Fresno and San Diego counties, via the cargo pathway
Reproduction and growth of the Southern Leopard Frog, Lithobates sphenocephalus utricularius (Harlan, 1825), in Virginia: implications for seasonal shifts in response to global climate change
No full textAn examination of 750 museum specimens of the Southern Leopard Frog (Lithobates sphenocephalus) collected during 1938‐1989 from eastern Virginia (USA) provided comparative life‐history data from the northeastern portion of this species geographic range. Individuals were collected in all months except December. Testis size was largest and incidence of gravid females was highest during fall and spring. In both sexes, fat storage was lowest during late‐winter‐spring, which is indicative of increased activity and commencement of breeding. Incidence of food in stomachs was lowest in late winter and relatively high thereafter, especially in males. Geographic trends in five lifehistory traits were corroborated for the Southern Leopard Frog in this study, including breeding season, egg size, mean adult body size, sexual size dimorphism, and larval metamorphosis season. In response to hotter summers and milder winters, as predicted to occur with climate change, the reproductive characteristics for this species in Virginia will likely shift to resemble contemporary reproductive patterns of southern populations.</jats:p
Calotes versicolor
No full textCalotes versicolor (Daudin, 1802) HOLOTYPE. Presumably in the Paris museum, but apparently lost (Auffenberg & Rehman 1993). TYPE LOCALITY. Not given by the author; designated to Pondicherry, India by Smith (1935). DISTRIBUTION. A tropical Asian lizard widely distributed from the extreme SE Iran through Pakistan and India, S China and SE Asia including Sumatra. Introduced to Borneo, S Oman, Kenya, and USA (Arnold 1986a; Das et al. 2008; Šandera & Starostová 2009; Meshaka 2011). DISTRIBUTION IN IRAN. Fig. 6. Sistan and Baluchistan Prov. HABITAT. An arboreal lizard occurring wherever there are trees or shrubs available, most common by water streams and riversides. Although it can tolerate considerable aridity, in desert habitats it is confined to oases and vegetation along the water courses (Khan 2006). SE Iran represents the westernmost projection of the species’ autochthonous range, however, it is found here only on date palms and its presence may be caused by humanmediated transfer (Anderson 1999). REFERENCES. Minton (1966); Anderson (1974, 1999); Auffenberg & Rehman (1993); Hallermann (2000); Mobaraki et al. (2013).Published as part of Šmíd, Jiří, Moravec, Jiří, Kodym, Petr, Kratochvíl, Lukáš, Yousefkhani, Seyyed Saeed Hosseinian, Rastegar-Pouyani, Eskandar & Frynta, Daniel, 2014, Annotated checklist and distribution of the lizards of Iran, pp. 1-97 in Zootaxa 3855 (1) on page 8, DOI: 10.11646/zootaxa.3855.1.1, http://zenodo.org/record/492970
"A Pocket Guide to Salamanders of Pennsylvania" by Walter E. Meshaka, Jr., and Joseph T. Collins. 2012. [book review]
No full textVolume: 128Start Page: 93End Page: 9
GEOGRAPHIC VARIATION IN SELECTED LIFE HISTORY TRAITS OF THE EASTERN NARROWMOUTH TOAD, GASTROPHRYNE CAROLINENSIS (HOLBROOK, 1836), ALONG THE NORTHEASTERN EDGE OF ITS GEOGRAPHIC RANGE
No full textWe examined the Eastern Narrowmouth Toad,Gastrophryne carolinensis, along the northeastern edge of its geographic range in Virginia to determine the extent to which selected life history traits in this region adhered to patterns associated with a latitudinal gradient in this species. As in studies elsewhere, a significant difference in mean adult body size between males (28.3 mm SVL) and females (30.1 mm SVL) was typical of this species as was the absence of a relationship between clutch size and female body size. Mean body sizes of both sexes appeared larger in northern populations than southern counterparts. Geographically predictable, the breeding season in Virginia was severely curtailed in response to climatic constraints despite extended fertility, and its breeding activity peaked in mid-summer as it has been reported to do throughout its geographic range. Thus, along the northern edge of its geographic range, the Eastern Narrowmouth Toad retains its ability breed for a longer season despite present climatic constraints, an advantage in the face of climate change that could alter timing and duration of acceptable breeding atmospheric conditions
RED-BELLIED SNAKE (STORERIA OCCIPITOMACULATA) COPULATION IN SOUTH DAKOTA
No full textStoreria occipitomaculata is a small, terrestrial species of snake that occurs across much of eastern North America (Ernst and Barbour 1989, Ernst 2002, Ernst and Ernst 2003). Due to this widespread distribution, S. occipitomaculata faces varied climates that likely result in regional differences in reproductive phenology. Much of what is known about the reproductive ecology of S. occipitomaculata has been documented from the southeastern portion of its range in North America (South Carolina: Semlitsch and Moran 1984, North Carolina: Willson and Dorcas 2004), though Blanchard (1937) studied a population from northern Michigan. The exact reproductive timing in this species has been difficult to determine due to the longevity of sperm in female oviducts (Trapido 1940), but reproduction is suspected to occur throughout the spring, summer, and fall (Wright and Wright 1957, Fitch 1970). In eastern North America, multiple sources report reproduction in this species as occurring in the spring and fall (e.g., DeGraaf and Rudis 1983, Mitchell 1994, Beane et al. 2010), with direct observations of copulation reported in May (North Carolina: Palmer and Braswell 1995), July (New York: Bishop 1927), and September (Kentucky: Cupp et al. 2012, New York: Trapido 1940, Pennsylvania: Meshaka 2010). Fewer details are available on when this species reproduces in the northern Great Plains along the western boundary of its distribution, with a single published observation of a road-killed female found in August in Manitoba, Canada, with a copulatory plug, suggesting recent copulation (Gregory 1977)
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