The discovery and delimitation of species has changed dramatically over time. Species delimitation practices became more thorough and formal in the 1900s with the introduction of detailed studies of geographic variation, contact zones, and reproductive isolating mechanisms. In the 1960s, genetic methods for examining the allelic composition across many loci began to be used to test for gene flow and to delimit species boundaries. Methods for DNA sequencing were invented in the late 1970s, just as I started graduate school, when I set my sights on applying the vast stores of information in genomes to understanding biodiversity. In the late 1980s, a new method for rapid amplification of mitochondrial DNA led to “barcoding” of species and the subsequent splitting of species into mitochondrial haplotype groups. By the 1990s, widespread sequencing of nuclear genes led to the development of models that incorporated multispecies coalescent theory (MSC). Molecular-based methods provide new insights and opportunities for species delimitation, but many species delimitation studies do not adequately consider violations of underlying model assumptions before making taxonomic changes. Inadequate sampling and a lack of attention to contact zones often leads to the over-splitting of species into geographically proximate groups of populations. I predict the future will bring a synthesis of many older practices (careful sampling, with attention to reproductive isolation, contact zone analysis, and geographic variation) with the new powerful analysis of genomic data sets, leading to a reevaluation and reversal of much of the recent overly enthusiastic splitting of geographically variable species.

Heterogeneity in detection probabilities arises from many parts of a survey design and can introduce bias into estimates of site occupancy probability. We examined the effect of two important sources of heterogeneity, observer and survey method, on occupancy estimates in a lizard community in west Texas, with a special emphasis on Dunes Sagebrush Lizard (Sceloporus arenicolus). Using line transects and visual encounter surveys, nine observers surveyed 72 sites. We detected 10 species of lizards in total; all 10 were detected using visual encounter surveys and only 4 were detected using transects. We determined observers to be an important variable in occupancy models for two of three species of lizards. Insufficient detections were made of the remaining seven species to reliably model occupancy. We conducted simulations to further investigate the impacts of observer variability on occupancy estimate bias and precision by using a range of known occupancy and detectability combinations. Precision in the occupancy estimate increased as the mean observer detection probability increased. Overall, bias was minimized by conducting surveys with either 1) observers with high detection probabilities or 2) using teams of observers with mixed (high and low) detection probabilities.Modeling observer detection probabilities explicitly provided marginal improvement to the occupancy estimate in the simulations. The consistent variability in detection probability among observers has implications for the precision and bias in occupancy estimates and decisions should be made at the experimental design phase about how to approach this problem.

Florida is home to the largest number of invasive reptile species, including the abundant Anolis sagrei, of any U.S. state. This lizard species has largely displaced the native Anolis carolinensis because of its superior competitive ability and tolerance of urbanized habitats. One facet of the invasion of A. sagrei that has not received attention in the literature is its interactions with parasites, including the malaria protozoan Plasmodium. We studied the relative prevalence of Plasmodium floridense in two Anolis species at three sympatric sites in central Florida to determine the factors that affect the parasite's prevalence, incidence, and effects on blood cell counts. After catching lizards and making blood smears, we examined slides for the presence of Plasmodium and counted relative erythrocyte/ leukocyte ratios. Of the 101 lizards sampled, 31% of A. carolinensis were positive for P. floridense, as opposed to only 11% for A. sagrei. Date of capture was also an important factor, with June having the highest prevalence and March the lowest. Erythrocyte to leukocyte ratios differed with infection, averaging 3.15 ± 1.28 SD in infected lizards versus 4.28 ± 1.03 in uninfected lizards. Reduced infection by blood parasites may have been one of the many factors that allowed A. sagrei to successfully invade Florida and to become the superior competitor throughout its range. Additional studies of the effects of Plasmodium infection on competitive ability and fitness are needed to determine whether infection is a major contributor to invasion success.

We observed the behavior of overwintering Smooth Softshell Turtles, Apalone mutica, in an outdoor simulated pond with remote cameras. Submerged overwintering turtles partially buried themselves in a sand/mud substrate where they periodically raised and lowered the posterior portion of their body into the water column in a “push-up” fashion. Push-ups occurred with variable frequency and were similar in appearance and amplitude within and among individual turtles. Push-up frequency was positively correlated with water temperature and was paused more often at lower water temperatures. We also observed push-up behavior of A. mutica under simulated winter conditions in laboratory aquaria. Turtles maintained in water with 95–100% dissolved oxygen content executed pushups less frequently than turtles in water with lower oxygen content. Our observations of push-up behavior in A. mutica in an outdoor enclosure and laboratory are consistent with a respiratory ventilation function. Softshell turtles, known to be highly intolerant of anoxia, ostensibly sustain aerobic metabolism by creating currents that replenish the oxygen-depleted boundary layer between the turtle's thin vascularized skin and oxygenated water.

Foraging theories evaluate how animals make choices in prey. Some important factors in prey selection are size of prey and distance to pursuit, which can be affected by prey availability, ease of capture, and the time for chasing, handling, and ingesting prey. We examined prey size selection in an ambush (sit-and-wait) predator, the Eastern Fence Lizard, Sceloporus undulatus, in Maryland and Delaware, USA. We tested whether animals selected prey by size by presenting two sizes of prey (crickets) in a choice test in the field and measured latency to attack prey through a series of presentations of mealworm prey at different distances, recording the distance and time to attack. Adult males preferred larger prey and female juveniles preferred smaller prey. Distances to pursue prey did not differ between sexes but males had a longer attack latency than did females. Mean sprint speed on a vertical surface correlated with maximum burst speed, body mass, and body condition; males were more likely to run than were females, particularly during the spring. We found that our ambush foragers show prey size preferences and demonstrate a distance beyond which they will pursue prey. Because prey size preferences were not predicted by body size alone and cut-off distances did not vary seasonally, factors affecting foraging behavior warrant further attention.

Roads impact wildlife in a variety of direct and indirect ways. Roads may act as barriers to dispersal, lead to decreasing population size and genetic diversity, change animal behavior, result in direct mortality, and increase habitat disturbance. Road mortality is especially detrimental to long-lived species, such as freshwater turtles, whose population persistence relies on high adult and subadult survivorship to counter high egg and hatchling mortality. The Spotted Turtle (Clemmys guttata) is a small-bodied, freshwater turtle species that is listed as endangered in Canada and proposed for federal listing in the United States. We used a population viability analysis to attempt to quantify the impact that road mortality has on two distinct populations of Spotted Turtles. The baseline model for the North Wetland Complex (NWC) population predicted a probability of quasi-extinction within 150 yr of 20%. The baseline model for the South Wetland Complex (SWC) predicted a probability of quasi-extinction within 150 yr of 24%. Including an estimate of road mortality (modeled as a reduction in adult survival through annual catastrophic events) into the models, the probability of quasiextinction within 150 yr changed to 93% for the NWC and 94% for the SWC. Our results highlight the critical importance that anthropogenic additive adult mortality has on small populations of turtles and the necessity of detailed demographic studies to detect potential declines in populations of long-lived species.

Size and function of digestive organs in snakes are modulated by feeding frequency and by the energetic demands of reproduction. This allows snakes to minimize costs and maximize the energetic gains from predation. Examination of Yellow Anacondas (Eunectes notaneus) acquired from sustainable management activities provided an opportunity to study the predation in this species. Field evidence poses doubts on the historical assumption that they are infrequent feeders. We probed this question by analyzing data of postprandial modulation of stomach, liver, kidneys, and heart, as well as fat bodies in the light of foraging theory. This allowed us to evaluate intersexual differences in the allometry of such structures. We analyzed 95 snakes, and we show that both sexes have similar organ masses. However, livers in females were 55% larger than in males. We also show, for the first time, the postprandial hypertrophy of a digestion-related organ in a wild snake. In specimens with prey in their intestines, postprandial response was significant for only the liver (57% of increase). No other organ presented postprandial hypertrophy. The biggest prey represented 23% of the snake's body mass, and the prey mass had no significant effect on organ mass. The meager or absent postprandial hypertrophy observed here is similar to frequent foraging snakes. The abundance and levels of consumption of small prey are high in habitats occupied by Yellow Anacondas at our study site. We believe that field data and physiological postprandial responses allow us to regard Yellow Anacondas as active foraging snakes that feed frequently.

Nuptial pads are patches of thickened skin, associated with sexually dimorphic skin glands, present only in the thumbs and fingers of male anurans, and hence considered dimorphic sexual characters. Despite the morphological description for many species, the evolution and function of nuptial pads are still unclear. In this study, we describe the presence of nuptial-pad–like structures in females of two species of Melanophryniscus and compare their morphology and histology to males' nuptial pads. The epidermal modifications found in females are conical papillary epidermal projections, similar to the structures found in males; however, the density of these projections in males is twice the average found in females. Also, the nuptial-pad–like structure found in females cannot be considered an actual nuptial pad, because there are no specialized skin glands associated with the structure. This study brings the first records of epidermal modification in females of Melanophryniscus and provides the description of male nuptial pads for the genus.

Scinax constrictus is the only species in the Scinax rostratus group endemic to the Cerrado in Brazil. Here, we describe the external morphology and internal oral features of the S. constrictus tadpole and compare it with other known tadpoles of the S. rostratus group. The tadpole of S. constrictus has a wide dorsal gap and a ventral gap in the marginal papillae of the oral disc, a labial tooth row formula of 2(2)/3(1) with P3 modified as a labial arm, and without infralabial and lingual papillae.

The Neotropical genus Pseudopaludicola includes 24 species distributed throughout South America. Herein, we formally describe the 25th member of this Neotropical clade as a new species: Pseudopaludicola jazmynmcdonaldae sp. nov. from an Amazon-Cerrado transitional zone in Brazil. The recognition of this new species is supported by adult morphology, advertisement call, and molecular data. It is diagnosed mainly by the following characters: small size; upper eyelids smooth, with no palpebral tubercles; heel smooth, with no enlarged conical tubercle; terminal phalanges knobbed, with no T-shaped terminal phalanges or expanded toe tips; relatively short hind limbs (tibiotarsal articulation just reaching the corner of the mouth); single, subgular, smooth, dark vocal sac in life, with no warty texture; and an advertisement call composed of regular series of short multipulsed notes, emitted at high rate.

Tail loss (autotomy) is common in populations of many caudate amphibians and often is assumed to be an antipredator adaptation, but few studies have examined associated costs and ecology of tail loss in natural populations of salamanders. We examined tail loss in two populations of the Georgetown Salamander (Eurycea naufragia) over a 2-yr period. The percentage of individuals with tail loss at Swinbank Spring compared to Twin Spring (both in central Texas) differed significantly (14.17 vs. 4.92%, respectively), and there was more frequent tail loss in salamanders captured in spring–summer than in fall–winter. At Swinbank Spring, larger salamanders experienced more frequent tail loss than smaller salamanders; the frequency of tail loss did not differ between gravid salamanders and nongravid salamanders at either population. Body condition, as measured by relative tail width, was lower in salamanders that had experienced tail loss at Swinbank Spring. These observations indicate that tail loss is common in populations of E. naufragia and that patterns of tail loss in this species are associated with important ecological characteristics.