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Terrapene carolina triunguis (Three-toed Box Turtle) and Terrapene ornata ornata (Ornate Box Turtle) are sympatric in areas of eastern Texas. Usually, these species are easily distinguished by shell shape and pigmentation. However, many turtles from areas of eastern Texas have characteristics of both Three-toed and Ornate Box Turtles, which we presume to be a result of hybridization. We collected, marked, and measured 103 box turtles from Walker County for morphometric analyses. Because of our limited number of Ornate Box Turtles sampled (n = 6), an additional 68 specimens from eastern Texas in the Texas Cooperative Wildlife Collection (TCWC) were examined, and the carapace and plastron measured to characterize species-specific shell morphology for Ornate Box Turtles. Multivariate analyses indicated that all morphometrics of carapace shape (length, width, curvature length, and curvature width) loaded heavily (r = 0.929, 0.897, 0.936, and 0.955, respectively) on the first principle component (Factor 1) and explained 86.41% of the variation in shell morphology and best distinguished observed differences between species and putative hybrids. Putative hybrids demonstrated a shell morphology similar to that of Three-toed Box Turtles and differed significantly from that of Ornate Box Turtles. Of the total 177 turtles examined, we considered 78 to be Three-toed Box Turtles, 74 to be Ornate Box Turtles, and 25 to be hybrids between the two parent species.
There is a paucity of data on mammal species richness in the Piedmont physiographic province of the Carolinas, especially in north-central South Carolina. Over the last 12 years, I conducted field surveys, searched the literature, and queried numerous museums and agencies to locate records of mammals from the Piedmont province of South Carolina. I recorded 43 species of mammals, four of which are listed as species of state concern, from six counties in north-central South Carolina. Baseline information on mammal species occurrence is critical to future studies and issues of management and conservation.
The primary resource of temperate forest treeholes is leaf litter, and different insects specialize on particular stages of decay. Helodes pulchella (scirtid beetle) takes part in a processing chain by shredding leaf litter and creating material for other consumers. We hypothesized that variation in scirtid density and resources influences the insect community. To test this, we manipulated scirtid beetle and resource densities in field mesocosms. We used a two-factor design (3 litter levels by 3 scirtid densities), and monitored insect communities from April 2004 to June 2005. We detected no statistically significant effects of scirtids on leaf decay. However, during the first season, species richness was higher in mid-summer in the presence of low scirtid density compared to treatments with high scirtid densities or those with no scirtids. The dominant species was Aedes triseriatus (eastern treehole mosquito) and its abundance was unaffected by either scirtid or leaf litter. However, mean pupal mass of mosquitoes was greater at low scirtid densities. Facilitation is suggested by the combination of high mosquito densities and large pupal mass. Densities of Culicoides guttipennis (ceratopogonid midge) were higher at intermediate and high resource levels without scirtids, compared to treatments with any scirtids, suggesting a negative interaction between midges and scirtids. We demonstrated strong, and not always positive, effects of scirtid beetles on insect communities in water-filled treeholes.
The assemblage of bacteria and fungi from black (Solenopsis richteri)/hybrid imported fire ant (BIFA/HIFA) mounds were obtained from four counties in northeast Mississippi. These locations were selected due to high concentrations of BIFA/HIFA that were free from red imported fire ants (RIFA). Mound samples were obtained during October, November, and December in 2003 and January 2004. Patterns of species composition and diversity (species richness) were evaluated from mound soil, mound plant debris, and ant bodies. A total of 5742 isolates consisting of 58 bacterial and 35 fungal taxa were obtained. The most common bacteria identified included Chryseobacterium indolegenes, Stenotrophomonas maltophilia, Actinomadura yumaensis, and Arcanobacterium haemolyticum. Approximately 66% of the fungi cultured belonged to the artificial assemblage Fungi Imperfecti, including Curvularia geniculata, Penicillium spp., Nigrospora sphaerica, and Monoacrosporium leptosporium. The insect pathogen Beauveria bassiana was obtained from mound soil, mound plant debris, and ant bodies, with the greatest percentage from ant bodies. Species richness for bacteria and fungi were both highest from mound soil at 53 and 30 taxa, respectively, and lowest, with 8 bacteria and 25 fungal taxa, from mound plant debris. Species diversity for bacteria was also highest from mound soil, and highest for fungi from ant bodies than the other two isolation conditions. Evenness values for bacteria (0.72–0.80) and fungi (0.74–0.77) during each sampling date had moderate to high relative abundance (1.0 = highest level possible), indicating similarity of taxa among bacteria and among fungi from the four sampling dates. Coefficient of community values comparing sampling dates for bacteria and fungi were greatest between the first and last sampling date (October and January). Temperatures during those dates ranged from 14.4 °C to 28.9 °C in October and −2.8 °C to 10.0 °C in January. As a continuation of this research, cultures of the different bacteria and fungi obtained in this study are currently being evaluated for their potential as biological control agents of BIFA/HIFA and RIFA that occur in Mississippi.
Gap-analysis models of vertebrate species richness are primarily created based on literature and expert review to predict individual species' occurrences and overall richness of vertebrates. Such models need validation based on empirical data to assess their accuracy. We describe and apply a new technique for assessing the accuracy of spatially explicit models. We evaluated the accuracy of South Carolina gap-analysis vertebrate models of predicted occurrence for reptile, amphibian, and mammal species on the Savannah River Site, SC, by comparing the agreement between gap-analysis models with models derived from multi-year monitoring data. We determined the species model agreement, commission and omission errors, and spatial correspondence in both single-species and richness models, and spatial correspondence of nodes of high richness. Average species agreement (accuracy) between models was 63%, with similar commission and omission error rates. Where there was spatial correspondence in single-taxon analyses, up to 15% of species identities differed in richness maps. Further refinement of vertebrate models will improve their accuracy, critical for the application of gap analyses to conservation decision-making.
Pteronotropis welaka (Bluenose Shiner) has a fragmented range throughout the Southeast, but its apparent rarity may reflect a low probability of detection during surveys. Our objectives were to obtain up-to-date status information for populations in southwest Georgia and to account for incomplete detection in our estimate of the proportion of sites occupied. We detected Bluenose Shiner at 5 of 39 sites (13%) sampled during 2004 and 2005 and estimated detection probability (p) and the proportion of sites occupied (psi) from seine-haul data. Models containing habitat covariates as predictors of p and psi provided a better description of the data than models without covariates for Bluenose Shiner and three other minnow species. Regardless of the model structure, the probability of detecting Bluenose Shiner during a single seine haul was substantially lower than for the other minnow species (3–8% vs. 13–33%). However, estimates of the proportion of sites occupied (corrected for incomplete detection) were similar to observed occupancy rates for all four species because of the large number of seine hauls we made at each site. The modeling approach we followed increased our confidence in survey results and provided information on where and how much to sample in future surveys. It has broad application to future surveys and monitoring programs for rare aquatic species in the southeastern United States.
Forestiera acuminata (swamp privet) is a common wetland shrub/small tree native to the southeastern United States. We examined several possible dispersal avenues for the plant. We tested germination of seeds exposed to various treatments, including passage through Ictalurus punctatus (Channel Catfish) guts, and conducted other tests and observations to infer seed-dispersal pathways. Channel Catfish consumed swamp privet drupes and defecated viable seeds, confirming that they are seed dispersers. Bombycilla cedrorum (Cedar Waxwings) ate the carbohydrate-rich drupes, and we predict that they disperse the seeds. We also inferred passive seed dispersal by water. Diverse dispersal pathways may allow for effective seed dispersal under a wide range of environmental conditions. Growing in wetlands and riparian areas, the plant experiences extreme annual variation in hydrologic conditions, which should influence the importance of the various dispersal pathways among years.
A survey of the vascular flora of Mason Mountain Wildlife Management Area, located in the Llano Uplift of Central Texas, was conducted between spring of 2001 and spring of 2006. A total of 693 species and infraspecific taxa in 103 families and 376 genera were documented from 14 plant associations. Poaceae (117 species), Asteraceae (102 species), Fabaceae (46 species), and Euphorbiaceae (31 species) were the families with the largest number of species. Five taxa, Campanula reverchonii (basin bellflower), Eriogonum tenellum Torr. var. ramosissimum (tall buckwheat), Isoetes lithophila (rock quillwort), Packera texensis (Llano groundsel), and Tradescantia pedicellata (Edwards Plateau spiderwort) are endemic to the Llano Uplift, while 24 others are endemic to Texas. Other noteworthy taxa included Isoetes piedmontana (Piedmont quillwort), Pilularia americana (American pillwort), and Senecio ampullaceus (Texas ragwort).
Important details of the reproductive ecology of many freshwater fishes of the species-rich southeastern USA are still poorly known. Two such species are Notropis asperifrons (Burrhead Shiner), and Notropis stilbius (Silverstripe Shiner). Both are endemic to the Mobile Basin, AL. To determine timing and patterns of reproductive effort, collections were made of as many as 20 individuals of each species at roughly four-week intervals from March through September. Female gonadal somatic index (GSI) data averages for each collection indicate that both species peak in reproductive activity in April. Both species still had reproductively competent female GSI values as late as July 31. Examination of ovarian tissue indicates that Burrhead Shiner oocytes are usually larger at equivalent developmental stages. Burrhead Shiners exhibit sexual size dimorphism with larger females, while Silverstripe Shiners do not.
We sampled fishes from nearshore, continental shelf (≈30 m) to shelf-slope, deep-water habitats (≈100 m) in the Mid-Atlantic Bight (MAB) and South Atlantic Bight (SAB) during winter (2005) to explore compositional differences among temperatures and depths. Trawl surveys conducted by the National Marine Fisheries Service do not typically sample winter fish assemblages concurrently from both the MAB and SAB, although increased concern over changes in distribution of species such as Pterois volitans (Lionfish) may warrant such studies. We collected 41 families and 68 species of fish, and found that temperature and depth influenced their distribution. More species were collected in the SAB where temperature was 10 °C higher. At nearshore sites of SAB, we collected reef fishes (Chaetodontidae; Fistulariidae) and Stenotomus chrysops (Scup). At deep water sites of SAB, we collected Ophichthidae, Acropomatidae, and Scorpaenidae. Assemblages of the MAB were dominated by Squalus acanthias (Spiny Dogfish), particularly at nearshore sites. Pomatomus saltatrix (Bluefish) and Scomber scombrus (Atlantic Mackerel) were also abundant in the MAB. Our results highlight distributions of some fish species during winter. However, more data are necessary for understanding macroecological patterns of marine fish distribution in the northwestern Atlantic Ocean, especially as they relate to the interactive effects of temperature and depth on populations.
Endemic species with limited geographic ranges are particularly sensitive to habitat loss and degradation. In order to conserve such species, we tend to focus on optimal habitats (e.g., for land acquisition), but human-altered habitats may also be of conservation value if species can persist in these environments. We evaluated the occurrence of a lizard endemic to scrub and sandhill habitats in Florida, the threatened Plestiodon reynoldsi (Sand Skink), to determine whether it occurs in human-altered vegetation types. From 2003–2004, we quantitatively sampled 46.5 ha (composed of 7 vegetation and 10 soil types) for the distinctive trails this fossorial lizard leaves in sandy areas. The Sand Skink was present in equal relative densities across all vegetation types, including disturbed areas such as pastures and abandoned citrus groves. Further, we detected Sand Skinks on all well-drained sandy soils we sampled. Thus, Sand Skinks can persist in human-altered habitats, at least when underlying soils are suitable for their presence and have not been modified. In general, more Sand Skinks were found in larger habitat patches, regardless of whether patches were characterized by vegetation or soil. Our results suggest that anthropogenically altered habitats have conservation value for Sand Skinks (and possibly other ecologically similar species) and that future studies should focus on the effects of restoring these habitats on resident populations of this species.
Until recently, two surface-dwelling species of multi-ribbed brook salamanders (i.e., the metamorphic Eurycea multiplicata griseogaster [Graybelly Salamander], and the strictly paedomorphic E. tynerensis [Oklahoma Salamander]) were recognized as living in the Missouri Ozarks. The current understanding is that a single species (Oklahoma Salamander) is resident in the Ozarks, and that this species is polymorphic for life-history mode from population to population. We recently discovered that multi-ribbed salamanders at two locations in Christian and Barry Counties, MO, show striking polymorphism in eye-coloration, with individuals possessing either gold or black irises. To test whether the gold- and black-eyed forms may be different species, we conducted a phylogeographic analysis of mtDNA variation in multi-ribbed salamanders across the Missouri Ozarks. We present sequence data from the mitochondrial cytochrome-b gene that show that transforming and paedomorphic individuals, and the alternative eye-color morphs can all arise from the same mitochondrially defined matriline, and thus seem to comprise a single species. We hypothesize that color-pattern variation in multi-ribbed salamanders is under simple genetic control.
West Nile virus (WNV) is an endemic arboviral pathogen that occurs throughout most of the United States and is typically maintained through a bird-mosquito-bird transmission cycle. The ecological significance of the virus is high due to its ability to infect and cause disease in humans, livestock, and wildlife. West Nile virus infection of many vertebrate species causes signs of viral illness, including encephalitis that may result in mortality. Infection by WNV has recently been detected in captive Alligator mississippiensis (American Alligators) in Georgia and Louisiana, and in both captive and free-ranging alligators in Florida. However, additional surveys for WNV in populations of free-ranging alligators within the southeastern USA have not been conducted. The purpose of this study was to survey free-ranging alligators in south Louisiana for active WNV infection. Blood samples were collected from 93 alligators captured at Rockefeller Wildlife Refuge in Cameron Parish, LA, during May 2006 and were screened for WNV using reverse transcriptase polymerase chain reaction (RT-PCR). All samples (100%) tested negative for WNV, indicating a lack of detectable active infection in these animals. Additional surveys of the occurrence of WNV in alligators throughout the southeastern USA are needed to determine the susceptibility of these reptiles to the virus, effects on the health of infected populations, and the potential role of alligators in the maintenance and transmission of the virus.
We examined predator-prey relationships of young Bairdiella chrysoura (Silver Perch) collected in Mississippi Sound by comparing the diet to fish standard length (2.5–30.0 mm SL) and mouth width (MW). Silver Perch displayed a diel feeding pattern, with the most active feeding occurring from midnight until noon. As Silver Perch SL increased, prey number, frequency, and volume plus prey width increased. Calanoid copepods and mysid shrimp were the dominant prey, with mysids becoming prominent as Silver Perch SL increased. Cluster analysis supported this pattern as Silver Perch ≤5 mm SL consumed a homogenous material and a few copepods, fish 5–10 mm SL preyed upon calanoid copepods, and then fish in larger size classes shifted their diet to mysid shrimp as MW increased and fish became more robust. Silver Perch SL was linearly related to MW (MW = 0.097 [SL] 0.245; r2 = 0.891).
Shrews are insectivorous opportunistic foragers occupying moist habitats characterized by high vegetative composition. Shrews characteristically have poorly developed eyesight and rely on olfactory and auditory senses for efficient foraging. Two Blarina hylophaga (Elliot's short-tailed shrew) recently trapped in East Texas did not have externally visible eyes. Further examination during specimen preparation revealed both had developed eyes, but lacked developed, opened, or functional eyelids. A third shrew, collected in Bastrop County, TX, had developed eyes and eyelids, however, the external openings were abnormally small. All three shrews were adults and alive in traps, suggesting no ill effects due to the reduction or absence of eye openings and further suggesting little or no effect on the survival of these individuals.