Geoffrey R Smith

Denison University · Department of Biology

The Balsas Basin (BB) is a biogeographic province in south-central Mexico that straddles the Mexican Transition Zone and the Neotropical region. We provide a list of the amphibian and reptile species of the BB based on a detailed review and update of recent species lists of its constituent states. The BB is home to 51 native amphibian and 155 nativ...

The Chihuahuan Desert biogeographic province in Mexico is the largest of the fourteen bio-geographic provinces of the country. This biogeographic province hosts a diverse array of amphibian and reptile species, with 262 native species, including 53 amphibians and 209 reptiles, accounting for a significant portion of Mexico's total amphibian (~12%)...

The Pacific Lowlands (PL) of Mexico hosts a rich diversity of amphibians and reptiles, comprising 326 native species (76 amphibians and 250 reptiles) across 45 families. This region is significant from a biodiversity standpoint, accounting for 23.3% of Mexico's total amphibian and reptile species, with 30 species being endemic to the PL. Notably, t...

Aquatic ecosystems are often negatively affected by invasive species. However, biotic resistance by native species, either by competition or predation, can reduce the impacts of invasions by non‐native species. The Western Mosquitofish (Gambusia affinis) is one of the most impactful invasive species of freshwater fish and cause declines in native f...

The Transvolcanic Belt (TVB) of Mexico is a biogeographic province of significant biodiversity, acting as a transition zone between eastern and western Mexico. Using available literature, we collected species lists for amphibians and reptiles in Mexican states within the TVB biogeographic province, updating them with additional literature. The TVB...

Os habitats de riacho das salamandras do gênero Ambystoma no México estão sendo degradados pelas atividades humanas, o que pode ter efeitos prejudiciais sobre suas populações. Assim, é importante compreender melhor o uso de habitas e micro-habitatas por parte desses anfíbios. Utilizamos experimentos de preferência para examinar a seleção do tipo (c...

Herein, we present an updated list of the species of amphibians and reptiles that inhabit Nayarit, Mexico. In the years since the publication of a previous list in 2016, threats to amphibians and reptiles in Nayarit have continued unabated and efforts to more fully catalogue the richness of Nayarit’s herpetofauna have continued. Nayarit harbours 16...

Western mosquitofish, Gambusia affinis , have been introduced around the world, and can affect native fish through competition and predation. The diet of G. affinis may therefore determine the extent of their interactions with native species. We examined stomach contents of G. affinis from two ponds in central Ohio in 2010, 2015, and 2016. In Olde...

Mexico is a megadiverse country with high amphibian and reptile richness. Understanding how Mexico’s herpetofauna is shared among Mexican states can contribute to developing conservation plans by figuring out which states may need to coordinate conservation actions. We generated species lists for the herpetofauna for all Mexican states, and used hi...

The characteristics of microhabitats in streams can drive the distribution of tadpoles. We experimentally examined microhabitat selection of tadpoles of Dryophytes plicatus . We used a series of choice experiments to test if tadpoles had preferences for particular substrate types, substrate colors, and vegetation. Tadpoles of D. plicatus had a stro...

Temporally separated species are often thought to have limited competition over a shared resource. However, early arriving species may consume a limited resource such that later-arriving species have access to fewer resources and thus experience competitive effects, even if they are temporally separated (i.e., they experience legacy effects from th...

Plethodontid salamanders often possess the ability to detect and avoid hazards in the environment which may be important for survival. We examined whether the two main colour morphs of Plethodon cinereus differ in their avoidance of cues from a potential predator ( Thamnophis sirtalis ) and whether P. cinereus avoided cues from T. sirtalis of diffe...

Studies of elevational variation in diets in lizards have often found shifts in diet composition among elevations. Herein, we studied the diets of Sceloporus variabilis from six populations found in a variety of habitats along an elevational gradient (3–1900 m) in Puebla and Veracruz, Mexico. Diets of S. variabilis for the six populations were simi...

Mite prevalence and load can vary among populations and species of lizards. We report on chigger mite (Eutrombicula alfreddugesi) prevalence and load in a temperate population of Xenosaurus fractus and a subtropical population of Xenosaurus rectocollaris. Mites were more prevalent and found in greater numbers (i.e., higher load) on X. rectocollaris...

Growth rates of ectotherms are frequently affected by environmental conditions, such as temperature, precipitation, and prey availability. However, local adaptation to environmental conditions could influence geographic variation in growth rates. We studied growth rates of the Flathead Knob‐scaled Lizard, Xenosaurus platyceps , from a tropical popu...

Amphibian populations living at high elevations or latitudes often face harsh environmental conditions, including freezing winter temperatures. At the more northern extent of their distribution and at high elevations, salamanders in the genus Ambystoma have been observed at or near freezing temperatures.

Mexico is a megadiverse country with high endemicity in its herpetofauna. We examine how species richness, proportion of state and country endemic species, and proportion of species in a category of conservation concern using listings in the International Union for Conservation of Nature (IUCN) Red List and the Secretaría del Medio Ambiente y Recur...

The endangered, endemic salamander, Ambystoma altamirani, is distributed in streams in the Transvolcanic Belt around Mexico City. Like other Mexican ambystomatids, A. altamirani is threatened by several anthropogenic stressors, including land use changes. Here we examine how aspects of the terrestrial habitat, such as the distance to wooded habitat...

Chigger mites (Family Trombiculidae: genus Eutrombicula) are common ectoparasites on lizards. We report on Trombulicid mite prevalence of the lizard, Xenosuarus platyceps, from a temperate population, El Madroño, and a tropical population, Gómez Farías, in Tamaulipas, Mexico from 2000-2003. Mite prevalence was more than twice as high in El Madroño...

Water loss and gain rates of amphibians are important to understanding their ecology, especially for plethodontid salamanders. We report the first estimates of repeatability of relative water loss and gain rates of the two major colour morphs of the Eastern Red-backed Salamander, Plethodon cinereus , in the fall and spring seasons. Repeatability of...

We examined the prevalence (% of turtles examined) of leeches (Placobdella parasitica) and algae (likely Arnoldiella sp.) on Chrysemys picta found in 4 recently created ponds in central Ohio. Chrysemys picta in ponds with fish were less likely to have leeches and more likely to have algae than those in ponds without fish. Across all ponds, males an...

Bite force can be an important aspect of a lizard’s organismal performance, and is likely to be subject to influence by ambient conditions including an individual’s thermal environment. We examined the effects of body temperature (T b ) on initial bite force of rock- and crevice-dwelling individuals of three species of lizards: Abronia graminea (An...

In lizards, flight initiation distance (FID), the distance between a prey individual and a predator when escape begins, can be affected by numerous intrinsic and extrinsic factors, including sex, temperature, and level of conspicuousness. Here we report on a study of FID in a population of Ornate Tree Lizards, Urosaurus ornatus, from the Sierra de...

Amphibians often select oviposition sites based on a variety of cues that indicate the level of risk in the oviposition habitat. Surprisingly, the role of aquatic vegetation or habitat structure/complexity in anuran oviposition site selection has not been extensively studied even though it might affect perceived risk. We examined the effects of fre...

Introduction of exotic predators or runoff of fertilizers can alter aquatic food webs, in particular zooplankton communities, through top-down and bottom-up effects. In a mesocosm experiment, we manipulated the density of Western Mosquitofish (Gambusia affinis) and nutrient levels (nitrate and phosphate independently) and observed effects on zoopla...

We used a 36-yr study of a turtle community in a northern Indiana lake to examine shell anomalies and temporal changes in their frequency in 3 species. The overall frequency of shell anomalies was 17% in painted turtles (Chrysemys picta), 11% in northern map turtles (Graptemys geographica), and 18% in red-eared sliders (Trachemys scripta elegans),...

The relationship between body and substrate color for Ambystoma altamirani (Caudata: Ambystomatidae) from the Arroyo los Axolotes, Mexico. To determine whether the coloration of Ambystoma altamirani varies and whether the color is related to the color of the salamander’s substrate, A. altamirani from the Arroyo los Axolotes, state of México, Mexico...

Environmental temperatures often regulate the activity and physiological processes of ectotherms. Because environmental temperatures can vary significantly among seasons, lizards exposed to different thermal conditions in different months could differ in how they thermoregulate or behave. Here, we present a combination of field, laboratory, and mod...

The State of Mexico has a unique combination of geographic characteristics and topography that promotes a high biodiversity. Unfortunately, continued human population growth of the metropolitan areas of Mexico City and Toluca have degraded the environment of the State of Mexico, which threatened its wildlife. An updated checklist of the amphibians...

Mexico City houses one of the most populous urban areas of the world, and the modification of its natural habitat likely influences the biological diversity found there. In particular, amphibians and reptiles are likely affected by these modifications. Herein, we present an updated list of the species of amphibians and reptiles that inhabit Mexico...

Despite being one of the smallest states in Mexico, the high diversity of habitats in Morelos has led to the development of a rich biota made up of a mixture of species typical of the Neovolcanic Axis and the Sierra Madre del Sur. However, recent expansion of cities in Morelos is likely to have consequences for the state’s herpetofauna. Here a chec...

The streams in the mountains surrounding the Valley of Mexico often contain salamanders and anurans. Knowledge of these species is relatively poor, however. We report observations on predation and reproduction in two species from these streams, Ambystoma altamirani and Dryophytes plicatus.

Sinaloa possesses a rich biota with unique characteristics due to its proximity to the northern deserts, the tropical lowlands of the south, and the temperate environments of the western slopes of the Sierra Madre Occidental in Mexico. However, threats to its environment makes understanding the biological diversity of Sinaloa crucial. A checklist o...

Colima is the fourth smallest Mexican state, covering only 0.3% of the surface area of Mexico, but due to the remarkable diversity of physiographic and environmental conditions present in Colima it contains a high biological diversity. We generated an up-to-date herpetofaunal checklist for Colima, with a summary of the conservation status of Colima...

Lizards in the genus Xenosaurus are crevice-dwelling lizards. Their crevice-dwelling habit may constrain their ecology; thus one might predict there could be limited variation in several ecological traits among species. Here we report on aspects of the ecology of the recently described Xenosaurus fractus from the Sierra Nororiental of Puebla, Mexic...

Lizards in the genus Xenosaurus are crevice-dwelling lizards. Their crevice-dwelling habit may constrain their ecology; thus one might predict there could be limited variation in several ecological traits among species. Here we report on aspects of the ecology of the recently described Xenosaurus fractus from the Sierra Nororiental of Puebla, Mexic...

Body size, growth, and longevity in Northern Map Turtles (Graptemys geographica) from Dewart Lake in northern Indiana were studied from 1979 to 2016. Based on captures of 214 males (72 recaptures) and 99 females (40 recaptures), we generated von Bertalanffy growth equations which corroborated our growth curves based on counts of plastral growth rin...

Sonora has a rich natural diversity, including reptiles and amphibians. Sonora’s location on the United States-Mexico border creates some unique conservation challenges for its wildlife. We compiled a list of the amphibian and reptile species currently known for Sonora, summarized the conservation status of these species, and compared our list of s...

Females often decide where to place their eggs or offspring based on the relative risks and benefits of a location. One trade‐off may be between ovipositing with predators and ovipositing with competitors. Many amphibians show risk‐sensitive oviposition and select oviposition sites based on offspring performance. We examined differential ovipositio...

Ecology of Sceloporus gadsdeni (Squamata: Phrynosomatidae) from the central Chihuahuan Desert, Mexico. Populations of Sceloporus cyanostictus Axtell and Axtell, 1971 from southwestern Coahuila have been described as a new species, Sceloporus gadsdeni Castañeda-Gaytán and Díaz-Cárdenas, 2017. Sceloporus cyanostictus is listed as Endangered by the IU...

—Although initially applied to endotherms, Bergmann’s Rule (body size correlated with latitude) has also been demonstrated for a number of ectothermic taxa, including turtles. We examined body size and growth in the Pond Slider (Trachemys scripta) at the northern edge of its range in Indiana. We then compiled body size data from across the range of...

Recreational boating can have significant impacts on freshwater turtle individuals and populations through a variety of mechanisms, including direct injuries due to propeller strikes. We monitored the incidence of propeller wounds in four species of freshwater turtles in Dewart Lake in northern Indiana, USA, nearly annually from 1979-2014. Overall,...

Predation by native and non-native predators on the eggs, embryos, and early stage tadpoles can affect the recruitment of offspring into a population. We examined the effects of native (Little Brown Mudbugs, Cambarus thomai ; overwintered Rana tadpoles; Common Green Darner, Anax junius , larvae) and non-native (Western Mosquitofish, Gambusia affini...

Pollutant exposure can affect tadpole activity or affect their ability to respond to predator cues. One commonly used chemical in aquatic ecosystems, particularly those in suburban or rural areas, are dyes used to color or tint pond water. Little is known about how such dyes impact amphibians. We examined the effects of Tetra Pond Water Shade pond...

A summary of the species of amphibians and reptiles of the state has been compiled, including their geographic distributions, habitats, and conservation statuses. The herpetofauna of San Luis Potosí consists of 41 species of amphibians and 141 species of reptiles. San Luis Potosí shares the highest number of species with Hidalgo and Tamaulipas, and...

A summary of the species of amphibians and reptiles of Durango, as well as their geographic distributions, habitat, and conservation status have been compiled. The herpetofauna of Durango consists of 36 species of amphibians and 120 species of reptiles. Durango shares the most species with Chihuahua (74.0%), and shares fewer species with Sinaloa (4...

Surface waters are likely to be contaminated by both pesticides and fertilizers. Such contamination can result in changes in community composition if there is differential toxicity to individual taxa. We conducted a fully factorial mesocosm experiment that examined the single and interactive effects of environmentally realistic concentrations of ni...

Introduction of nonnative salmonids into fishless aquatic ecosystems often can have negative effects on these ecosystems. Amphibians appear to be particularly susceptible to the introduction of trout. Nonnative Rainbow Trout (Oncorhynchus mykiss) have been introduced to Mexico, including to streams in the mountains around Mexico City that are home...

The absence of predators is often invoked to explain the ability of non-native species to successfully invade a habitat, however native species can control or regulate populations of invasive species through predation. To better understand the regulation of invasive Gambusia affinis (Western Mosquitofish), we conducted a laboratory experiment to ex...

Laterality has been found in a variety of reptiles. In turtles, one important behaviour is the righting response. Here, we studied laterality of righting response of two species of freshwater turtles, the Painted Turtle (Chrysemys picta) and the Eastern Musk Turtle (Sternotherus odoratus). We found evidence of individual-level laterality in rightin...

In Mexico, many species of Ambystoma are endangered, but unfortunately little is known about their natural history and ecology. We report on aspects of the natural history of A. leorae, a critically endangered endemic salamander, from the Río Tonatzin, State of México, Mexico. We observed egg masses, which were attached to vegetation, from April to...

How individuals, and ultimately species, use resources determines much about their ecology. We examined diet and microhabitat use in four anuran species along the Río Salado, Puebla, Mexico. Dryophytes (Hyla) arenicolor and Incilius occidentalis had specialized diets, eating primarily ants and termites, respectively. Both Exerodonta xera and Lithob...

The populations of ambystomatid salamanders around Mexico City are subject to a variety of threats, and some populations may be in decline. Three Ambystoma species found around Mexico City and in central Mexico are A. altamirani, A. leorae, and A. rivulare, and these three species are subject to a variety of conservation threats. We compiled a data...

The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high t...

High levels of salinity often have lethal and sublethal effects on amphibians. In Mexico, salinization is threatening some rivers in arid and semi-arid regions. Here, we report the results of an experiment examining the effects of salinity and density on Pine Toad (Incilius occidentalis) tadpoles from the Río El Sabino in the Tecomavaca Canyon in O...

We examined the diets of 43 juveniles of the lizard Uma exsul from Coahuila, Mexico. The diet was composed primarily of adult and larval beetles. The diets of two females collected at the same time and place as the juveniles included beetles as the most important item but hemipterans, ants, and other hymenopterans were also important. Our observati...

Chihuahua is Mexico’s largest state, and its physiographic complexity affects the distribution of its herpetofauna. We list amphibians and reptiles for the state of Chihuahua, with their conservation status. We also compare this list to those of six adjoining states in the United States and Mexico (New Mexico, Texas, Coahuila, Durango, Sinaloa, and...

We compiled an inventory of the amphibians and reptiles of the Cuautlapan Valley, Veracruz, Mexico based on field surveys and museum and literature records. We found a total of 78 species: 28 amphibians (6 Salamanders and 22 anurans); and 50 reptiles (three turtles, 18 lizards, and 29 snakes). These taxa represent 26 families (eight amphibian famil...

The feeding of wildlife by ecotourists has become increasingly popular, but its effects are not well studied. The endangered Allen Cays Iguana is known to occur naturally on only two small cays in the northern Exuma Islands (The Bahamas). One of those cays, Leaf Cay (4 ha) has an easily accessible beach to which up to 150 people converge each day t...