WHAT IS A HERPETOLOGIST AND HOW CAN I BECOME ONE?

The following is the first in the JNAH series in which we address a variety of topics on herpetology based on essays from our upcoming book “How to Be a Herpetologist,”. We will also answer frequently asked questions we and other professional herpetologists receive from students, colleagues, and the general public about herpetology as a career or an avocation

Seminatrix, S. pygaea

Number of Pages: 5Integrative BiologyGeological Science

Relationship between threshold and suprathreshold perception of position and stereoscopic depth.

We seek to determine the relationship between threshold and suprathreshold perception for position offset and stereoscopic depth perception under conditions that elevate their respective thresholds. Two threshold-elevating conditions were used: (1) increasing the interline gap and (2) dioptric blur. Although increasing the interline gap increases position (Vernier) offset and stereoscopic disparity thresholds substantially, the perception of suprathreshold position offset and stereoscopic depth remains unchanged. Perception of suprathreshold position offset also remains unchanged when the Vernier threshold is elevated by dioptric blur. We show that such normalization of suprathreshold position offset can be attributed to the topographical-map-based encoding of position. On the other hand, dioptric blur increases the stereoscopic disparity thresholds and reduces the perceived suprathreshold stereoscopic depth, which can be accounted for by a disparity-computation model in which the activities of absolute disparity encoders are multiplied by a Gaussian weighting function that is centered on the horopter. Overall, the statement equal suprathreshold perception occurs in threshold-elevated and unelevated conditions when the stimuli are equally above their corresponding thresholds describes the results better than the statement suprathreshold stimuli are perceived as equal when they are equal multiples of their respective threshold values

Upland Habitat Quality and Historic Landscape Composition Influence Genetic Variation of a Pond-Breeding Salamander

Understanding the temporal and spatial scale at which habitat alteration impacts populations is important for conservation and management. Amphibians have declined more than other vertebrates, and pond-breeding species are particularly susceptible to habitat loss and fragmentation because they have terrestrial and aquatic life stages. One approach to management of pond-breeding species is protection of core upland habitat surrounding the breeding pond. We used genetic variation as an indicator of population status in a common amphibian species, spotted salamanders (Ambystoma maculatum), to determine how amount of suitable upland habitat relates to population status in the greater Charlotte, North Carolina, USA metropolitan area. We developed candidate models to evaluate the relative influence of historical and contemporary forested habitat availability on population genetic variation at two spatial scales of upland area (164 m and 2000 m) at four time intervals over the past seven decades (1938, 1978, 1993, 2005). We found that historical land cover best predicted contemporary allelic richness. Inbreeding coefficient and observed heterozygosity were not effectively predicted by forest cover at either spatial or temporal scales. Allelic richness was best predicted at the smaller spatial scale in the 1993 time interval. Predicting and understanding how future landscape configuration affects genetic variation of common and rare species is imperative for the conservation of amphibian and other wildlife populations

Can invasive Burmese pythons inhabit temperate regions of the southeastern United States?

Abstract Understanding potential for range expansion is critical when evaluating the risk posed by invasive species. Burmese pythons (Python molurus bivittatus) are established in southern Florida and pose a significant threat to native ecosystems. Recent studies indicate that climate suitable for the species P. molurus exists throughout much of the southern United States. We examined survivorship, thermal biology, and behavior of Burmese pythons from South Florida in a semi-natural enclosure in South Carolina, where winters are appreciably cooler than in Florida, but within the predicted region of suitable climate. All pythons acclimated to the enclosure, but most died after failing to seek appropriate refugia during sub-freezing weather. The remaining snakes used refugia but died during an unusually cold period in January 2010. Although all snakes died during the study, most survived extended periods at temperatures below those typical of southern Florida and none exhibited obvious signs of disease. Our study represents a first step in evaluating the results of climate matching models and we address factors that may affect range expansion in this invasive species

Monitoring herpetofauna in a managed forest landscape: effects of habitat types and census techniques

We surveyed the herpetofaunal (amphibian and reptile) communities inhabiting five types of habitat on a managed landscape. We conducted monthly surveys during 1997 in four replicate plots of each habitat type using several different methods of collection. Communities of the two wetland habitats (bottomland wetlands and isolated upland wetlands) were clearly dissimilar from the three terrestrial communities (recent clearcut, pine plantation, and mixed pine–hardwood forest). Among the three terrestrial habitats, the total herpetofaunal communities were dissimilar (P\u3c0.10), although neither faunal constituent group alone (amphibians and squamate reptiles) varied significantly with regard to habitat. Three survey techniques used in the terrestrial habitats were not equally effective in that they resulted in the collection of different subsets of the total herpetofauna. The drift fence technique revealed the presence of more species and individuals in every habitat and was the only one to detect species dissimilarity among habitats. Nonetheless, coverboards contributed to measures of abundance and revealed species not detected by other techniques. We suggest that a combination of census techniques be used when surveying and monitoring herpetofaunal communities in order to maximize the detection of species

Cold-induced mortality of invasive Burmese pythons in south Florida

Abstract A recent record cold spell in southern Florida (2-11 January 2010) provided an opportunity to evaluate responses of an established population of Burmese pythons (Python molurus bivittatus) to a prolonged period of unusually cold weather. We observed behavior, characterized thermal biology, determined fate of radio-telemetered (n = 10) and non-telemetered (n = 104) Burmese pythons, and analyzed habitat and environmental conditions experienced by pythons during and after a historic cold spell. Telemetered pythons had been implanted with radio-transmitters and temperature-recording data loggers prior to the cold snap. Only one of 10 telemetered pythons survived the cold snap, whereas 59 of 99 (60%) non-telemetered pythons for which we determined fate survived. Body temperatures of eight dead telemetered pythons fluctuated regularly prior to 9 January 2010, then declined substantially during the cold period (9-11 January) and exhibited no further evidence of active thermoregulation indicating they were likely dead. Unusually cold temperatures in January 2010 were clearly associated with mortality of Burmese pythons in the Everglades. Some radiotelemetered pythons appeared to exhibit maladaptive behavior during the cold spell, including attempting to bask instead of retreating to sheltered refugia. We discuss implications of our findings for persistence and spread of introduced Burmese pythons in the United States and for maximizing their rate of removal

Circulating Naturally-Occurring Anticoagulants before Treatment and after Recovery from SARS-CoV-2 Infection in Ghana

Background: Disturbance in naturally-occurring anticoagulants may contribute to the hypercoagulable state in COVID-19. This study determined the plasma antigen levels of protein C (PC), protein S (PS), antithrombin-III (AT-III), and thrombomodulin (TM) before treatment and after recovery from COVID-19. Materials and Methods: This cross-sectional study, conducted from February to August 2022 at Kumasi South Hospital, recruited sixty-five RT-PCR-confirmed COVID-19 participants. A venous blood sample was taken for full blood count (FBC) analysis using a 3-part fully automated haematology analyzer, and PC, PS, AT-III, and TM antigen levels measured using ELISA. The data were analyzed using SPSS version 26.0. P<0.05 was considered statistically significant. Results: Severe COVID-19 participants had relatively lower haemoglobin (p<0.001), RBC (p<0.001), HCT% (p<0.001) and platelets (p<0.001), but higher RDW-CV% (p=0.013), WBC (p<0.001), and absolute lymphocyte counts (p<0.001) compared to those with the non-severe form of the disease. The overall prevalence of anaemia among the participants was 58.5%, and 32 (84.2%) and 6 (15.8%) of the anaemic participants had mild and moderate anaemia respectively. Protein C (p<0.001), PS (p<0.001) and ATIII (p<0.001) levels were lower among the severe COVID-19 participants than in the non-severe group. But severe COVID-19 group had higher TM levels (p<0.001) than the non-severe group. Again, participants had higher haemoglobin (p<0.001), RBC (p<0.001), HCT% (p=0.049), absolute neutrophil count (p<0.001) and platelets (p<0.001) after recovery from COVID-19 than the values on admission. Additionally, after recovery, participants had higher levels of PC (p<0.001), PS (p<0.001), and ATIII (p<0.001), but reduced TM (p<0.001). Conclusion: Severe COVID-19 patients had higher PC, PS, and AT-III, but lower TM levels. The changes in circulating anticoagulants may contribute to the hypercoagulable state of COVID-19. Blood cell indices are negatively affected during COVID-19. Complete recovery from the SARS-CoV-2 infection normalised the haematological indices. Assessment of naturally-occurring anticoagulants and the provision of anticoagulants are recommended in the management of COVID-19.   Doi: 10.28991/SciMedJ-2022-04-04-01 Full Text: PD

Therapeutic impact of cytoreductive surgery and irradiation of posterior fossa ependymoma in the molecular era: a retrospective multicohort analysis

PURPOSE: Posterior fossa ependymoma comprises two distinct molecular variants termed EPN_PFA and EPN_PFB that have a distinct biology and natural history. The therapeutic value of cytoreductive surgery and radiation therapy for posterior fossa ependymoma after accounting for molecular subgroup is not known. METHODS: Four independent nonoverlapping retrospective cohorts of posterior fossa ependymomas (n = 820) were profiled using genome-wide methylation arrays. Risk stratification models were designed based on known clinical and newly described molecular biomarkers identified by multivariable Cox proportional hazards analyses. RESULTS: Molecular subgroup is a powerful independent predictor of outcome even when accounting for age or treatment regimen. Incompletely resected EPN_PFA ependymomas have a dismal prognosis, with a 5-year progression-free survival ranging from 26.1% to 56.8% across all four cohorts. Although first-line (adjuvant) radiation is clearly beneficial for completely resected EPN_PFA, a substantial proportion of patients with EPN_PFB can be cured with surgery alone, and patients with relapsed EPN_PFB can often be treated successfully with delayed external-beam irradiation. CONCLUSION: The most impactful biomarker for posterior fossa ependymoma is molecular subgroup affiliation, independent of other demographic or treatment variables. However, both EPN_PFA and EPN_PFB still benefit from increased extent of resection, with the survival rates being particularly poor for subtotally resected EPN_PFA, even with adjuvant radiation therapy. Patients with EPN_PFB who undergo gross total resection are at lower risk for relapse and should be considered for inclusion in a randomized clinical trial of observation alone with radiation reserved for those who experience recurrence