56 research outputs found
Phylogenetic structure of Holbrookia lacerata (Cope 1880) (Squamata: Phrynosomatidae): one species or two?
No full textHibbitts, Toby J., Ryberg, Wade A., Harvey, Johanna A., Voelker, Gary, Lawing, A. Michelle, Adams, Connor S., Neuharth, Dalton B., Dittmer, Drew E., Duran, C. Michael, Wolaver, Brad D., Pierre, Jon Paul, Labay, Benjamin J., Laduc, Travis J. (2019): Phylogenetic structure of Holbrookia lacerata (Cope 1880) (Squamata: Phrynosomatidae): one species or two? Zootaxa 4619 (1): 139-154, DOI: 10.11646/zootaxa.4619.1.
FIGURE 8 in Phylogenetic structure of Holbrookia lacerata (Cope 1880) (Squamata: Phrynosomatidae): one species or two?
No full textFIGURE 8. Dorsal (top) and ventral (bottom) views of Plateau Spot-tailed Earless Lizard (Holbrookia lacerata) lectotype specimen collected by G.W. Marnock in May 1879 and housed at Smithsonian (USNM 10160).Published as part of Hibbitts, Toby J., Ryberg, Wade A., Harvey, Johanna A., Voelker, Gary, Lawing, A. Michelle, Adams, Connor S., Neuharth, Dalton B., Dittmer, Drew E., Duran, C. Michael, Wolaver, Brad D., Pierre, Jon Paul, Labay, Benjamin J. & Laduc, Travis J., 2019, Phylogenetic structure of Holbrookia lacerata (Cope 1880) (Squamata: Phrynosomatidae): one species or two?, pp. 139-154 in Zootaxa 4619 (1) on page 148, DOI: 10.11646/zootaxa.4619.1.6, http://zenodo.org/record/324848
Figure 1 in Natural history of the spot-tailed earless lizards (Holbrookia lacerata and H. subcaudalis)
No full textFigure 1. Current and historic distribution of Holbrookia lacerata (A; top photo of male) and H. subcaudalis (B; bottom photo of male) in Texas. Black stars indicate the study areas for each species. Photo credits: T.J. Hibbitts.Published as part of Hibbitts, Toby J., Walkup, Danielle K., LaDuc, Travis J., Wolaver, Brad D., Pierre, Jon Paul, Duran, Mike, Neuharth, Dalton, Frizzell, Shelby, Adams, Connor S., Johnson, Timothy E., Yandell, Danny & Ryberg, Wade A., 2021, Natural history of the spot-tailed earless lizards (Holbrookia lacerata and H. subcaudalis), pp. 495-514 in Journal of Natural History 55 (7-8) on page 500, DOI: 10.1080/00222933.2021.1907469, http://zenodo.org/record/547566
Figure 2 in Mitochondrial genetic variation within and between Holbrookia lacerata lacerata and Holbrookia lacerata subcaudalis, the spot-tailed earless lizards of Texas
No full textFigure 2. Bayesian phylogeny of whole mitochondrial genomes from Holbrookia lacerata lacerata and H. l. subcaudalis, with H. maculata and H. propinqua as outgroup taxa. Numerical values are Bayesian posterior probabilities; all other nodes represent values> 0.95. The scale bar represents percent genetic divergence.Published as part of Roelke, Corey E., Maldonado, Jose A., Pope, Blake W., Firneno, Thomas J., Laduc, Travis J., Hibbitts, Toby J., Ryberg, Wade A., Rains, Nathan D. & Fujita, Matthew K., 2018, Mitochondrial genetic variation within and between Holbrookia lacerata lacerata and Holbrookia lacerata subcaudalis, the spot-tailed earless lizards of Texas, pp. 1017-1027 in Journal of Natural History 52 (13-16) on page 1021, DOI: 10.1080/00222933.2018.1436726, http://zenodo.org/record/517439
Figure 3 in Life in the thornscrub: movementı home rangeı and territoriality of the reticulate collared lizard (Crotaphytus reticulatus)
No full textFigure 3. Box plots showing significant differences between log-transformed male and female reticulate collared lizard (Crotaphytus reticulatus) (a) Mean step length (m), (b) Minimum convex polygon (m2), (C) 95% kernel density estimation (m2), and (D) 50% kernel density estimation (m2). Movement parameters were estimated with GPS telemetry in Jim Hogg and Starr Counties, Texas (2015–17).Published as part of Ryberg, Wade A., Garrett, Timothy B., Adams, Connor S., Campbell, Tyler A., Walkup, Danielle K., Johnson, Timothy E. & Hibbitts, Toby J., 2019, Life in the thornscrub: movementı home rangeı and territoriality of the reticulate collared lizard (Crotaphytus reticulatus), pp. 1707-1719 in Journal of Natural History 53 (27) on page 1714, DOI: 10.1080/00222933.2019.1668491, http://zenodo.org/record/367035
Comparing Terrestrial Wildlife Diversity Between Native and Non-Native Grassland Ecosystems
No full textWildlife diversity is essential and valuable for the environment, society, and the economy. Grasslands have long been a biodiversity hotspot before anthropogenic impacts. In Texas, grasslands comprised much of the landscape in pre-settlement times. Today, 99% of native grasslands are lost. Human activity has significantly altered these grasslands through conversion to monocultural pastures, agriculture, invasive species introduction, and development. Conversion and degradation of native grasslands decrease biodiversity and decrease ecosystem functioning. In turn, this reduces ecosystem services that benefit human society. Diverse grassland systems provide services such as carbon sequestration, water retention and filtration, erosion control, and flood prevention. Native wildlife benefits include birds, insects, and bats that disperse seeds and provide pollination services, as well as game species, such as quail and deer, that provide a lasting heritage and livelihood to many peoples. In this study, we determine if there is a significant difference in the diversity of terrestrial wildlife taxa (herpetofauna, invertebrates, birds, small mammals, bats, and medium-sized and large mammals) between non-native and native grass-dominant ecosystems to understand the potential benefits of restoring native grass systems. Our study results found a significant (P<0.001) positive association between species richness (a measure of diversity) and native dominant vegetation systems. We found that overall, mammal, bird, herpetofauna, and invertebrate richness was nearly 2x greater in native grass-dominant vegetation types than in non-native grass-dominant vegetation types. This research may be used to demonstrate the quantifiable advantages of restoring and conserving native grasslands
Ecology and sexual selection of the common barking gecko (ptenopus garrulus)
No full textFaculty of Science
School of Animal,Plant and Enviromental Studies
0204322k
[email protected] investigated three mechanisms (endurance rivalry, contest competition, and mate choice) of sexual selection and the influence of multiple signals on intrasexual and intersexual encounters in the common barking gecko (Ptenopus garrulus). Aspects of the ecology of barking geckos were also studied to facilitate the investigation of sexual selection. Barking geckos exhibited sexual size dimorphism in relation to head size, with males having wider heads. No differences in diet or size of prey ingested were observed between the sexes, indicating that niche divergence was not occurring. Therefore, the difference in head width was best explained by sexual selection (male contest competition). Barking gecko diet was dominated by termites by number and volume. The peak reproductive season was in October for both sexes.
I used activity patterns to determine if males emerged before females from winter dormancy, a key assumption of the protandry-based mating system model. Activity patterns were significantly different between males and females. Males were active in higher numbers early in the breeding season. Male and female activity patterns along with evidence that male territories were established before female emergence, testicular recrudescence likely coincides with male emergence, and larger males have larger territories and better reproductive success, suggest that barking geckos have a protandry-based polygynous mating system. I also tested for clustering of geckos on the landscape to determine if barking geckos lek. Clustering was found to occur in some instances, but barking geckos did not
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meet the criteria for a ‘classical’ lek species because males use calling sites containing resources (a burrow) that are also used by females.
Lizards frequently rely on chemical cues to detect the presence of a conspecific. Male lizards in particular, may chemically sample potential refuges to avoid rivals. Barking geckos were equally likely to use an artificial refuge scented by another male compared to a control, indicating that males do not use scent when selecting refuges.
I assessed the role of two signals, one acoustic (dominant call frequency) and one visual (yellow throat patch), in advertising residency and aggressive behavior in barking geckos. Larger males defended the largest home ranges and home ranges were maintained through calling, which is negatively correlated with body size. Body size also predicted some behavioural responses to field-playback trials. Small males retreated from the playback and large males were found to be aggressive towards the playback. Small relative throat patch size was also correlated with aggression and charging the playback. Finally, call frequency was correlated with the behaviour of charging the playback. I suggest that the frequencies of barking gecko calls constitute a long-range signal of body size, used by males for remote rival assessment and to advertise home range boundaries.
I also assessed the role of multiple signals (acoustic and visual) in reproductive success and I studied the effect of one mechanism of sexual selection, endurance
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rivalry, on reproductive success. Activity levels were similar for males which bred compared to those that did not breed, suggesting that endurance rivalry is not a significant mechanism of sexual selection in this population. Body size was the best predictor of reproductive success, suggesting that call frequency functions as a long range signal of body size used by females to assess potential mates
Biodiversity Conservation in Sub-Saharan Africa: A Case Study of the African Dwarf Crocodiles (Osteolaemus Spp.)
No full textOverexploitation of wildlife is a leading threat to biodiversity in tropical Africa. Effective management requires integrating information on the extent of exploitation, distribution, and status of exploited species. I explore how trade filters affected the final destination of bushmeat for different species involved in the trade. I highlight the trade in reptiles, in particular African Dwarf Crocodiles (Osteolaemus tetraspis) to investigate why they are rare in markets yet ubiquitously hunted. Hunting locations and methods determined the types of species entering bushmeat markets while selling conditions and prices determined whether species were traded locally or in urban markets.
To prioritize conservation efforts of over-exploited species, it is important to determine the distribution and status of populations. I conducted detailed sampling of Osteolaemus populations in Cameroon and around the Cameroon Volcanic Line (CVL), to investigate the distributional limits and number of cryptic Osteolaemus species in the country. I found that O. tetraspis extends west beyond the CVL, thus, this mountain chain does not represent the distributional limit of this species. I also found O. osborni in Cameroon. I provided information on the population ecology of O. tetraspis and O. osborni in Cameroon to facilitate independent conservation of these two species. Both species are threatened in Cameroon based upon low encounter rates, young population structures and continued threats of habitat loss and hunting pressure.
Crocodilians link nutrients and energy between food webs through their movements across heterogeneous habitats. These connections may differ among habitats and as they undergo ontogenetic shifts in diet. I compared food web associations of Ostoelaemus species inhabiting a large river and small tributary using stable isotope analyses of carbon and nitrogen. Osteolaemus species inhabiting perennial rivers have aquatic food web associations as opposed to the largely terrestrial food web associations detected when they occupy swamp habitats. These species have large dietary overlap between juveniles, adults and, sexes.
Through my research, I have provided a working knowledge of the distribution, ecology, and hunting pressure of Osteolaemus species necessary for assessing their conservation status and developing sound management. These widely distributed species should be regionally managed to conserve their evolutionary diversity
On Understanding Anuran Communities: Sampling Acoustic Data for the Probability of Detection of Species Presence
No full textThe calculation of probabilities of detection based on calling behavior can be used for assessment and monitoring of cryptic amphibians. I monitored ten species of anurans nightly from 1 January to 31 December 2015 in Colorado County, Texas. I monitored the environmental factors that influence the calling phenology of the Blanchard���s cricket frog (Acris blanchardi), Green treefrog (Hyla cinerea), Cajun chorus frog (Pseudacris fouquettei), Eastern narrow-mouth toad (Gastrophryne carolinensis), Southern leopard frog (Lithobates sphenocephalus), Crawfish frog (Lithobates areolatus), Gulf coast toad (Incilius nebulifer), American bullfrog (Lithobates catesbeianus), Green frog (Lithobates clamitans), and Squirrel treefrog (Hyla squirella). I analyzed acoustic data coupled with environmental covariates at eight ponds to determine the detection probability and sampling effort of each species. The models I produced indicate that air temperature at the time of the survey and pond depth can influence the detection probability of eight of the ten species of frogs I found during my study. My study suggests conducting night surveys for five of the ten species of frogs when the pond depth is approximately 0.5 meters and when the air temperature is between 20 ��� 25 ��C. My models predict that ten or more repeated surveys are necessary to reliably detect a specific species whose probabilities of detection are less than 0.3 during the species��� active season. My models predict that no more than ten repeated surveys are necessary to reliably detect species whose probabilities of detection are greater than 0.3 during the species��� active calling season
Sexual Dimorphism in the Sceloporus undulatus Species Complex
No full textThe Fence Lizard (Sceloporus undulatus complex) is a wide ranging North American species complex occurring from the eastern seaboard westward through the great plains and central Rocky Mountains and into the American Southwest. A recent phylogeny suggests four species lineages occur within S. undulatus. Traits within an interbreeding species that are influenced by sexual selection are under different selection pressures and may evolve independently from the selective forces of habitat. Sceloporus lizards have several characters that are influenced by sexual selection. I investigated sexual size dimorphism and allometric relationships of body size (snout vent length), torso length, rear leg length and three measurements of head size in 12 populations from the four species in the S. undulatus complex (N=352) specifically looking for variation among the 4 species. Additionally I investigated the size of signal patches between males and females in three species (N=339 specimens of S. consobrinus, S. cowlesi, S. tristichus) of the S. undulatus complex. Sexual confusion, was recently described in a population of the Sceloporus undulatus complex occurring in White Sands, New Mexico and the behavior is correlated with variation in badge size between male and female lizards. To make inferences about sexual confusion at the species level I investigated the presence and absence of signal patches in female lizards, and compare the sizes of signal patches between males and females. My analyses suggest that torso length and head size are significant sources of sexual size dimorphism but the findings differ from earlier published investigations of sexually dimorphic characters in the species complex. I also find support for the S. undulatus complex being generally a female larger species complex. However two of the 12 populations I investigated displayed male biased sexual size dimorphism. Analysis of signal patches across three species of the S. undulatus complex suggests that sexual dimorphism in signal patch size for S. cowlesi and S. tristichus may not prevent sexual confusion. While the near total absence of signal patches in female S. consobrinus is evidence that sexual confusion is not possible with regards to signal patches
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