Gekkotan lizards are the most vocal of all squamates and a majority of species (exclusive of eublepharids and most diurnal geckos) are capable of producing both distress calls and more complex advertisement calls, the latter being typically restricted to males. Although the vocal characteristics of some individual species are known, this study presents the first effort to identify general patterns in vocalization and laryngotracheal morphology across a broad phylogenetic sampling of taxa. We recorded up to 10 parameters of sonographic data for 36 gecko species (25 of which were previously unsampled) in 6 of 7 gekkotan families. Advertisement calls are species and individual specific, and the dominant call frequency is negatively correlated with body size, supporting the interpretation that such calls provide information about identity and condition to conspecifics. Advertisement calls have a much narrower frequency bandwidth than distress calls, which are used to deter predators across a spectrum of auditory ranges. Features of laryngotracheal morphology, especially laryngeal size and tracheal dilation, are associated with acoustic properties of phonation, but do not exhibit a strong phylogenetic signal. Ancestral state reconstructions using parsimony and maximum-likelihood methods indicate that the gekkotan ancestor possessed a ring-shaped cricoid cartilage with distinct lateral processes and circumferentially continuous tracheal rings. With a substantial increase in the number and phylogenetic diversity of species sampled, our data largely confirm the generality of structural and functional patterns of gecko phonation previously inferred from focal studies of select taxa.

Reproductive seasonality is common among snakes, with mating, pregnancy, and birth or oviposition occurring only during few months of the year and modulated mainly by two environmental phenomena—temperature and rainfall. Species of Bothrops inhabit regions with varied climatic conditions, including those that are tropical, subtropical, equatorial, and semiarid. Bothrops atrox is an endemic and widespread species of the Amazon rain forest. Such habitat is characterized by an equatorial climate with little variability in temperature and humidity, but marked seasonality in intense precipitation. We investigated several aspects of the reproductive biology of B. atrox, including the reproductive cycle, the sexual segment of the kidney (SSK), sperm storage, and the possible influence of temperature and rainfall on pregnancy duration, birth, and spermatogenesis. Specifically, we examined museum specimens to describe sexual dimorphism, litter size, and male and female urogenital cycles through macroscopic and histological analyses. Females of B. atrox exhibited follicular recrudescence mainly from January to April (part of the wet season). Pregnant females were found throughout the year (except May), but births were found to occur mainly at the end of the dry season (August–October). Males exhibited SSK hypertrophy and sperm production in the wet season (November–April). Females were found to be larger than males, but males of B. atrox—as with other members of the B. atrox species complex—obtain relatively larger body sizes when compared with other species of Bothrops, which might be an adaptive response to male–male combat in this species. Together, our results show that B. atrox from Amazonia has a unique reproductive strategy (for each sex) among pit vipers, indicating greater reproductive plasticity when compared with its congeners.

The introduction of Brown Tree Snakes (BTS; Boiga irregularis) on Guam has had devastating impacts on native wildlife and human infrastructure, resulting in concerted efforts to control populations and prevent the spread of this invasive species to other islands. These control efforts, particularly aerial drops of acetaminophen, can eradicate BTS within target areas, but snakes can repopulate those areas via compensatory immigration. Therefore, understanding how gene flow corresponds to dispersal can add critical information for maximizing effectiveness of control efforts. To examine dispersal patterns of BTS on Guam from a genetics perspective, we genotyped 332 individual snakes at 22 microsatellite loci to test for the presence of physical barriers (e.g., roads) and spatial genetic structure associated with restricted dispersal. Brown Tree Snakes experience sufficient gene flow on Guam to resist any strong physical barriers, a likely interaction between their large population size and ability to cross physical obstacles such as roads. In addition, BTS exhibited isolation-by-distance across the entire study area, but those captured on Andersen Air Force Base in northern Guam appeared to disperse randomly regardless of sex. Overall, BTS experience high gene flow across Guam, particularly in less urbanized areas in northern Guam. Therefore, compensatory immigration will likely make complete eradication difficult without antisnake barriers.

Visual encounter survey efforts can be defined and constrained by duration, distance, or both duration and distance simultaneously. This study examines the optimal walking pace that will maximize the number of animal detections within a limited time frame. We predicted that animal sighting rate per unit of distance would decline with increasing pace, but that maximal sighting rate per unit of time would occur at some intermediate pace because walking faster means covering more ground and passing more animals that could potentially be detected. We conducted a controlled experiment during which we searched for Brown Treesnakes (Boiga irregularis) while walking 220-m-long transects at three different speeds. For transects inside the forest, detection rate per unit distance decreased (nonlinearly) with increasing pace. When considering catch per unit time, however, we found 5% more snakes at the medium pace compared with the slow pace, and 63% more snakes at the fast pace compared with the slow pace. The pattern appeared different for surveys along forest edges with higher vegetation density, in which snakes might be more difficult to spot. Surprisingly, pace had no detectable effect on the body sizes or perch heights of snakes successfully detected. Finding the optimal search pace for a particular study organism in a focal habitat has the potential to substantially increase survey cost-efficacy.

Multiple paternity of clutches is common in many vertebrates, including snakes, and understanding how frequently it occurs within a species is important for determining the role it might play in conserving that species. One such species, Drymarchon couperi (Eastern Indigo Snakes), is the subject of an ongoing captive-breeding program and repatriation project in the southeastern United States. Many characteristics of the reproductive biology of this species are poorly understood, including whether clutches are sired by more than one male, and which characteristics, if any, are selected in potential mates. Sexual dichromatism has been suggested to occur in this species and, as such, one characteristic that might play a role in sexual selection is color. Our first objective was to determine if multiple paternity occurs in source and repatriated populations of D. couperi. Second, we examined whether color might play a role in sexual selection or sex identification. Therefore, we also tested hypotheses examining associations between color, heritability, and multiple paternity. We found that multiple paternity likely occurred in ∼31% of the clutches. Furthermore, heritability of color was relatively high, but single-sired and multisired clutches were similar in color and in the variability of color within a clutch. We conclude that management of D. couperi could benefit by exposing captive-bred females to multiple males within a mating season. This will allow for use of stored sperm to inseminate eggs after release or for females to seek new mates among the repatriated population.

We describe a new Amazonian species of Adenomera that corresponds to one of the acoustic signals and morphs from Tambopata National Reserve (Adenomera “Forest Call I”) and to a confirmed candidate species (Adenomera sp. E) in the most recently published phylogeny for the genus. The new species is distinguished from all 19 described congeners by its unique advertisement call, consisting of a single multipulsed note, formed by 22–35 partly fused pulses (greatest pulse number recorded for the genus among species with partly fused notes). The new species is further distinguished from most congeners in having toe tips expanded into small discs. Its distribution is associated with the Amazonian region encompassing western Brazil (state of Acre), southeastern Peru, and north-central Bolivia.

The Neotropical dipsadid snake genus Atractus contains more species than any other genus of serpents. The type species for the genus, Three-lined Snakes (Atractus trilineatus), occurs in northern South America, as well as in the islands of Trinidad and Tobago. Little is known about the phylogenetic position of this fossorial snake. Here, we examine the genetic variation of this species. Phylogenetic analyses suggest that A. trilineatus is an early branch within Atractus, and is deeply divergent from all of the other 31 species within the genus included in our analyses. Populations of A. trilineatus from Trinidad and Tobago show a close genetic affinity with mainland populations from Guyana, and indicate recent vicariance following Late Pleistocene sea-level rises. Overwater dispersal events cannot be ruled out, however, especially for the colonization of Tobago. Our results add to the understanding of the complexity of the phylogeographic events in the eastern Caribbean with this ecologically constrained species.