Matthew A. Kwiatkowski

GEOGRAPHIC VARIATION IN SEXUAL SELECTION AMONG POPULATIONS OF AN IGUANID LIZARD, SAUROMALUS OBESUS (=ATER)

Abstract.— Geographic variation in selection pressures may result in population divergence and speciation, especially if sexual selection varies among populations. Yet spatial variation in targets and intensity of sexual selection is well studied in only a few species. Even more rare are simultaneous studies of multiple populations combining observations from natural settings with controlled behavioral experiments. We investigated how sexual selection varies among populations of the chuckwalla, Sauromalus obesus. Chuckwallas are sexually dimorphic in color, and males vary in coloration among populations. Using field observations and multiple regression techniques, we investigated how sexual selection acts on various male traits in three populations in which males differed in coloration. The influence of sexual selection on male coloration was then investigated in more detail using controlled experiments. Results from field observations indicate that phenotypic selection was acting on territory quality in all three populations. In two populations, selection was also acting either directly or indirectly on male coloration. Male color likely functions as an indicator of food resources to females because male color is based partly on carotenoid pigments. In controlled experiments, significantly more females from these two populations chose males with brighter colors over dull males, a result consistent with studies on carotenoid pigments in other taxa. In a third population, no evidence of sexual selection on male coloration was found in either the field study or controlled experiment. Lack of female preferences for male color in this population, in which chuckwalla densities are low and home ranges are large, may result from searching costs to females.

Problems with mitigation translocation of herpetofauna

Mitigation translocation of nuisance animals is a commonly used management practice aimed at resolution of human-animal conflict by removal and release of an individual animal. Long considered a reasonable undertaking, especially by the general public, it is now known that translocated subjects are negatively affected by the practice. Mitigation translocation is typically undertaken with individual adult organisms and has a much lower success rate than the more widely practiced conservation translocation of threatened and endangered species. Nonetheless, the public and many conservation practitioners believe that because population-level conservation translocations have been successful that mitigation translocation can be satisfactorily applied to a wide variety of human-wildlife conflict situations. We reviewed mitigation translocations of reptiles, including our own work with 3 long-lived species (Gila monsters [Heloderma suspectum], Sonoran desert tortoises [Gopherus morafkai], and western diamond-backed rattlesnakes [Crotalus atrox]). Overall, mitigation translocation had a low success rate when judged either by effects on individuals (in all studies reviewed they exhibited increased movement or increased mortality) or by the success of the resolution of the human-animal conflict (translocated individuals often returned to the capture site). Careful planning and identification of knowledge gaps are critical to increasing success rates in mitigation translocations in the face of increasing pressure to find solutions for species threatened by diverse anthropogenic factors, including climate change and exurban and energy development.

Effects of an Invasive Plant, Chinese Tallow (Triadica sebifera), on Development and Survival of Anuran Larvae

Abstract Amphibians are considered one of the most threatened vertebrate groups. Although numerous studies have addressed the many causes of amphibian population decline, little is known about effects of invasive plants. Chinese tallow (Triadica sebifera) is an exotic deciduous tree that has invaded the southeastern United States. Amphibian larvae in environments invaded by T. sebifera may be impacted negatively as autumn leaf litter decomposes in natal areas. We compared effects of leaf litter decomposition from T. sebifera and two native tree species on survival and development of four species of anuran larvae from eastern Texas. Larvae from Pseudacris fouquettei, Lithobates (Rana) sphenocephalus, Hyla versicolor, and Incilius (Bufo) nebulifer were introduced into mesocosms containing leaf litter from one of the three tree species. Pseudacris fouquettei and L. sphenocephalus, species that breed earlier in the year, had lower survival within the T. sebifera pools. Pseudacris fouquettei were smaller in T. sebifera mesocosms compared with native tree mesocosms, whereas L. sphenocephalus were larger in T. sebifera mesocosms. Hyla versicolor showed significant developmental and morphological differences in T. sebifera mesocosms; however, survival was not significantly different among treatments. Leaf litter treatment did not affect survival or development in I. nebulifer. Our results suggest that breeding season may determine how each species survives and develops in an environment with T. sebifera leaf litter. Triadica sebifera leaf litter breaks down faster than native species; therefore, negative effects may be short lived but pose a greater threat to species that breed soon after leaffall.

Variation in Conspicuousness among Populations of an Iguanid Lizard, Sauromalus obesus (= ater)

Abstract The appearance of an organisms color pattern is a function of numerous variables, including the background on which the organism is observed. Hence, color patterns that appear similar or conspicuous when taken out of context, may, in reality, appear quite different when viewed in a natural setting. I investigated the relative conspicuousness of chuckwallas, Sauromalus obesus (= ater) among three populations in which males differ in their coloration. The color pattern of male and female chuckwallas was compared to the background color of rocks on which individuals were observed basking or displaying. Data were also collected on predation pressures and the thermal environment to see whether there was any association with conspicuousness. Male tail and body conspicuousness, and female tail conspicuousness, varied among the three populations. In all populations, male tail color was more conspicuous than male body color and, within all populations, males were more conspicuous than females. However, males and females were not equally conspicuous among populations; females from one population were as conspicuous as males from a different population. Conspicuousness appeared to be negatively associated with predation pressures. Little evidence was found to suggest that thermal considerations influenced color variation among the three populations. The role of chuckwalla conspicuousness is also discussed in the context of sexual selection.

Synergistic effects of the invasive Chinese tallow (Triadica sebifera) and climate change on aquatic amphibian survival.

Changes in climate and the introduction of invasive species are two major stressors to amphibians, although little is known about the interaction between these two factors with regard to impacts on amphibians. We focused our study on an invasive tree species, the Chinese tallow (Triadica sebifera), that annually sheds its leaves and produces leaf litter that is known to negatively impact aquatic amphibian survival. The purpose of our research was to determine whether the timing of leaf fall from Chinese tallow and the timing of amphibian breeding (determined by weather) influence survival of amphibian larvae. We simulated a range of winter weather scenarios, ranging from cold to warm, by altering the relative timing of when leaf litter and amphibian larvae were introduced into aquatic mesocosms. Our results indicate that amphibian larvae survival was greatly affected by the length of time Chinese tallow leaf litter decomposes in water prior to the introduction of the larvae. Larvae in treatments simulating warm winters (early amphibian breeding) were introduced to the mesocosms early in the aquatic decomposition process of the leaf litter and had significantly lower survival compared with cold winters (late amphibian breeding), likely due to significantly lower dissolved oxygen levels. Shifts to earlier breeding phenology, linked to warming climate, have already been observed in many amphibian taxa, and with most climate models predicting a significant warming trend over the next century, the trend toward earlier breeding should continue if not increase. Our results strongly suggest that a warming climate can interact with the effects of invasive plant species, in ways we have not previously considered, to reduce the survival of an already declining group of organisms.

Morphological Diagnosability of Aspidoscelis arizonae (Squamata: Teiidae) as an Indication of Evolutionary Divergence in the Aspidoscelis inornata Complex

Lizards of the gonochoristic Aspidoscelis inornata (Little Striped Whiptail) complex are ubiquitous components of vertebrate faunas in diverse habitats in the southwestern United States and northern Mexico. One of these, Aspidoscelis arizonae ( = A. inornata arizonae, Arizona Striped Whiptail), is extant at only a few grassland areas in southeastern Arizona, but nonetheless played an important evolutionary role in the hybrid origins of seven obligatory parthenogenetic species. Although recognized as a distinct species by many, A. arizonae lacks a valid species description and only anecdotal data argue for its recognition. We were unable to separate it from geographically proximate A. inornata in southwestern New Mexico, using diagnostic morphological features (i.e., number of stripes, dark field coloration, sky blue ventral suffusion) previously used to delineate aspidoscelids. Furthermore, we evaluated additional diagnostic characters (i.e., body size plus ten meristic characters) in samples of A. arizonae and A. i. llanuras from three adjacent counties, and found no significant size or meristic differences (P > 0.05). A canonical variate analysis of A. arizonae (n  =  30), A. pai (40), A. inornata spp. (18), and A. i. llanuras (32) across seven meristic characters revealed A. arizonae as indistinguishable from A. i. llanuras (i.e., 30% misclassifications). Apart from formal nomenclature, there are only two morphological groups among the foregoing samples, A. pai and a pooling of the other three. Data from all analyses in this study suggest that either A. arizonae is a cryptic species or a peripheral isolate unworthy of species status. Las lagartijas de reproducción sexual del complejo Aspidoscelis inornata (Huico Liso) son componentes importantes de la fauna de vertebrados en diversos hábitats en el suroeste de los Estados Unidos y norte México. Una de estas, Aspidoscelis arizonae ( = A. inornata arizonae, Huico Liso de Arizona), está limitada a unas cuantas áreas en el suroeste de Arizona, sin embargo, tuvo un papel evolutivo importante en los orígenes híbridos de siete especies partenogenéticas obligadas. Aunque es reconocida como una especie distinta, A. arizonae carece de una descripción válida para la especie y únicamente datos anecdóticos han sido argumentados para su reconocimiento. En una re-evaluación taxonómica, no pudimos separar a esta especie de poblaciones geográficamente cercanas de A. inornata en el suroeste de Nuevo México, utilizando características morfológicas diagnósticas (esto es, número de rayas, coloración oscura de interespacios entre rayas dorsales, sufusión ventral azul cielo), previamente utilizadas para delimitar aspidoscelidos. Además, evaluamos caracteres diagnósticos adicionales (esto es, tamaño corporal más 10 caracteres merísticos) en muestras de A. arizonae y A. i. llanuras de tres condados adyacentes, y no encontramos diferencias significativas en tamaño o caracteres merísticos (P > 0.05). Un análisis de variables canónicas de A. arizonae (n  =  30), A. pai (40), A. inornata spp. (18), y A. i. llanuras (32) a través de siete caracteres merísticos reveló que A. arizonae es indistinguible de A. i. llanuras (esto es, 30% de clasificación incorrecta). Aparte de la nomenclatura formal, únicamente hay dos grupos estadísticamente válidos entre las muestras anteriores, A. pai y un grupo de otras tres. Datos de todos los análisis en este estudio cuestionan el reconocimiento de A. arizonae como una población aislada que merezca el estatus de especie.

Road-edge effects on herpetofauna in a lowland Amazonian rainforest

The impact of roads on the flora and fauna of Neotropical rainforest is perhaps the single biggest driver of habitat modification and population declines in these ecosystems. We investigated the road-edge effect of a low-use dirt road on amphibian and reptile abundance, diversity, and composition within adjacent lowland Amazonian rainforest at San José de Payamino, Ecuador. The road has been closed to vehicle traffic since its construction in 2010. Thus, effects from vehicle mortality, vehicle-related pollution, and road noise were not confounding factors. Herpetofauna were surveyed using both visual encounter surveys and drift fences with pitfall and funnel traps at varying distances from the road. Structural and microclimate features of the forest were measured at each sampling distance. Several habitat variables were found to differ at intermediate and interior sampling distances from the road compared to forest edge conditions, suggesting the road-edge effect began to attenuate by the intermediate sampling distance. However, the edge effect on amphibians and reptiles appeared to extend 100 m from the road edge, as abundance and diversity were significantly greater at the interior forest compared to the forest edge. Additionally, assemblage composition as well as the hierarchical position of species shifted between sampling distances. Habitat predictor models indicate that amphibian abundance was best predicted by vine abundance, while both vine and mature tree abundance were the best predictors for species richness and diversity. Overall, and contrary to what might otherwise be expected, our results demonstrate that small, little-used road disturbances can nonetheless have profound impacts on wildlife.

Development and characterization of 16 microsatellite markers for the Louisiana pine snake, Pituophis ruthveni, and two congeners of conservation concern

We isolated and characterized 16 microsatellite loci from the Louisiana pine snake, Pituophis ruthveni. Loci were screened in 24 individuals from locations throughout its distribution in Louisiana and Texas. The number of alleles per locus ranged from 4 to 12, observed heterozygosity ranged from 0.200 to 0.875, and the probability of identity ranged from 0.043 to 0.298. We examined cross-species amplification at these loci in P. catenifer (bullsnakes and gopher snakes) and P. melanoleucus (pine snakes). These new markers provide tools for examining the conservation genetics of this species complex. Louisiana pine snakes face numerous threats: population densities are extremely low and their natural habitat has been severely altered and fragmented. In southern Canada, P. catenifer is at the northern extreme of its range and limited by the availability of suitable over-wintering sites. Hence, for these two species reduction of heterozygosity, potential for inbreeding, and increased effects of genetic drift are all of considerable conservation concern.