Genetic determination and JARID2 over-expression in a thermal incubation experiment in Casque-Headed Lizard.

Non-avian reptiles, unlike mammals and birds, have undergone numerous sex determination changes. Casque-Headed Lizards have replaced the ancestral XY system shared across pleurodonts with a new pair of XY chromosomes. However, the evolutionary forces that triggered this transition have remained unclear. An interesting hypothesis suggests that species with intermediate states, with sex chromosomes but also thermal-induced sex reversal at specific incubation temperatures, could be more susceptible to sex determination turnovers. We contrasted genotypic data (presence/absence of the Y chromosome) against the histology of gonads of embryos from stages 35-37 incubated at various temperatures, including typical male-producing (26°C) and female-producing (32°C) temperatures. Our work apparently reports for the first time the histology of gonads, including morphological changes, from stages 35-37 of development in the family Corytophanidae. We also observed that all embryos developed hemipenes, suggesting sex-linked developmental heterochrony. We observed perfect concordance between genotype and phenotype at all temperatures. However, analysis of transcriptomic data from embryos incubated at 26°C and 32°C identified transcript variants of the chromatin modifiers JARID2 and KDM6B that have been linked to temperature-dependent sex determination in other reptiles. Our work tested the validity of a mixed sex determination system in the family Corytophanidae. We found that XY chromosomes are dominant; however, our work supports the hypothesis of a conserved transcriptional response to incubation temperatures across non-avian reptiles that could be a reminiscence of an ancestral sex determination system.

Corytophanids Replaced the Pleurodont XY System with a New Pair of XY Chromosomes.

Almost all lizard families in the pleurodont clade share the same XY system. This system was meticulously studied in Anolis carolinensis, where it shows a highly degenerated Y chromosome and a male-specific X chromosome dosage compensation mechanism. Corytophanids (casque-headed lizards) have been proposed as the only family in the pleurodont clade to lack the XY system. In this study, we worked with extensive genomic and transcriptomic data from Basiliscus vittatus, a member of the Corytophanidae family that inhabits the tropical rainforests of Mexico. We confirmed that B. vittatus underwent a sex chromosome system turnover, which consisted in the loss of the pleurodont XY system and the gain of a new pair of XY chromosomes that are orthologous to chicken chromosome 17. We estimated the origin of the sex chromosome system to have occurred ∼63 Ma in the ancestor of corytophanids. Moreover, we identified 12 XY gametologues with particular attributes, such as functions related to the membrane and intracellular trafficking, very low expression levels, blood specificity, and incomplete dosage compensation in males.

Complex patterns of hybridization and introgression across evolutionary timescales in Mexican whiptail lizards (Aspidoscelis).

Identifying patterns of introgression across the tree of life is foundational to understanding general mechanisms that govern the impacts of gene flow on the speciation process. There are few vertebrate groups in which hybridization is associated with as large a diversity of outcomes as in North American whiptail lizards (Aspidoscelis). Of particular interest is that hybridization among divergent whiptail species has repeatedly led to the formation of unisexual (parthenogenetic) lineages. Understanding the hybrid origin of these unisexual lineages requires an accurate understanding of species boundaries among gonochoristic whiptails. Doing so has historically been an extremely challenging problem which, in part, may be a consequence of widespread hybridization and incomplete reproductive isolation among lineages. The lack of a robust phylogenetic framework and uncertainty in species boundaries precludes studies of general patterns and mechanisms of introgression among whiptail species. Here, we use genomic data to reconstruct a robust estimate of evolutionary history in the largest clade of whiptail lizards (A. sexlineatus species group) and use it to identify patterns of introgression. Our results indicate substantial introgressive hybridization and admixture has occurred among multiple lineages of whiptails across diverse evolutionary time scales, and illustrate their impact on phylogenetic inference. Thus, hybridization among whiptail species appears to have been a prominent feature throughout their evolutionary history, which could, in part, explain why parthenogenesis has evolved so many times in whiptails in comparison to other vertebrate groups.

How far do adult turtles move? Home range and dispersal of Kinosternon integrum.

We describe the home range and movements of a population of Kinosternon integrum in Tonatico, Estado de México, México, over 3.5 years (during rainy and dry season months) using radiotelemetry in 37 adult turtles. The results showed that the home range of K. integrum was 0.151 ± 0.051 ha using 50% kernel density estimator (KDE), and 0.657 ± 0.214 ha using 95% KDE; the home range did not vary between sexes. Kinosternon integrum showed low distances traveled 51.44 ± 4.50 m, where 87.3% (n = 373) of movements were <100 m. The distance traveled differed by season, and movement category (aquatic and terrestrial movements). The shortest distance occurred during the dry season, during which some individuals move to estivation sites, and these movements were shorter than movements to artificial ponds (cattle ponds). In this population, home range and movement are similar to other species of the genus Kinosternon. Overall, the results indicate than K. integrum are highly dependent on aquatic habitats, but also utilize the terrestrial habitats for different biological activities, and to maintain viable populations. Therefore, the conservation of the entire inhabited area is fundamental. This study highlights the need to increase the studies, in Central México, concerning habitat use of freshwater turtles in order to increase the efficiency of conservation strategies.

[Home range of Aspidoscelis cozumela (Squamata: Teiidae): a parthenogenetic lizard microendemic to Cozumel Island, México]. / Ámbito hogareño de Aspidoscelis cozumela (Squamata, Teiidae): una lagartija partenogenética microendémica de Isla Cozumel, México.

Home range is defined as the area within which an individual moves to acquire resources necessary to increase their fitness and may vary inter and intra-specifically with biotic and abiotic factors. This study details the home range of the parthenogenic lizard, Aspidoscelis cozumela, an active forager microendemic to Cozumel Island, México, with high preference for open sand beaches. The home range of A. cozumela was compared with other species of Aspidoscelis (gonochoric and parthenogenetic) and other lizards that occupy coastal habitats. Furthermore, the biotic and abiotic factors that may influence home range were analyzed. This study was conducted in the beach located on the East side of the island (area of 4,000 M2) that is composed primarily of halophyte vegetation with high levels of sunlight. From 1999 to 2001, nine samples were taken which included the dry, rainy, "nortes", and breeding seasons. During each sampling, capture-mark-recapture techniques were conducted and the date, time of day, and snout-vent length (SVL) were recorded to the nearest millimeter. Individuals were located in the study area using a bi-coordinate reference using 10 x 10 m subdivisions of the habitat. Home range and home range overlap were calculated using the convex polygon method in McPaal and home range/SVL correlation was tested using Pearson's correlation. To calculate females home range, three or more recaptures were considered. A total of 20 home ranges that averaged 45.1 ± 14.0 m2 were obtained and no correlation between SVL and home range size was detected (p = 0.9229, n = 20). However, removing individuals with outlier home ranges (females with home ranges > 100 m2, n = 2) resulted in a positive correlation with SVL (r = 0.61, p = 0.0072, n = 18). A 22.9 ± 5.7% overlap in home range was also detected. The small home range of A. cozumela represents the smallest home range within the Aspidoscelis genus recorded to date (including both parthenogenetic and gonochoric species) and contrasts the theoretical predictions of broad home ranges for widely foraging species. Thermoregulatory benefits and a high population density may explain the small home range of A. cozumela. Although this species is highly adapted to the environmental conditions present on the open sand beaches, anthropogenic effects on these habitats by the development of tourism infrastructure may jeopardize their existence on Cozumel Island.

Ámbito hogareño de Aspidoscelis cozumela(Squamata, Teiidae): una lagartija partenogenética microendémica de Isla Cozumel, México / Home range of Aspidoscelis cozumela (Squamata: Teiidae): a parthenogenetic lizard microen-demic to Cozumel Island, México

Home range is defined as the area within which an individual moves to acquire resources necessary to increase their fitness and may vary inter and intra-specifically with biotic and abiotic factors. This study details the home range of the parthenogenic lizard, Aspidoscelis cozumela,an active forager microendemic to Cozumel Island, México, with high preference for open sand beaches. The home range of A. cozumelawas compared with other species of Aspidoscelis(gonochoric and parthenogenetic) and other lizards that occupy coastal habitats. Furthermore, the biotic and abiotic factors that may influence home range were analyzed. This study was conducted in the beach located on the East side of the island (area of 4 000 m2) that is composed primarily of halophyte vegetation with high levels of sunlight. From 1999 to 2001, nine samples were taken which included the dry, rainy, "nortes", and breeding seasons. During each sampling, capture-mark-recapture techniques were conducted and the date, time of day, and snout-vent length (SVL) were recorded to the nearest millimeter. Individuals were located in the study area using a bi-coordinate reference using 10 x 10 m subdivisions of the habitat. Home range and home range overlap were calculated using the convex polygon method in McPaal and home range/SVL correlation was tested using Pearson's correlation. To calculate females home range, three or more recaptures were considered. A total of 20 home ranges that averaged 45.1 ± 14.0 m2 were obtained and no correlation between SVL and home range size was detected (p = 0.9229, n = 20). However, removing individuals with outlier home ranges (females with home ranges > 100 m2, n = 2) resulted in a positive correlation with SVL (r = 0.61, p = 0.0072, n = 18). A 22.9 ± 5.7% overlap in home range was also detected. The small home range of A. cozumelarepresents the smallest home range within the Aspidoscelisgenus recorded to date (including both parthenogenetic and gonochoric species) and contrasts the theoretical predictions of broad home ranges for widely foraging species. Thermoregulatory benefits and a high population density may explain the small home range of A. cozumela.Although this species is highly adapted to the environmental conditions present on the open sand beaches, anthropogenic effects on these habitats by the development of tourism infrastructure may jeopardize their existence on Cozumel Island.

El ámbito hogareño es el área dentro de la cual un individuo se mueve para adquirir recursos que incrementen su supervivencia. El ámbito hogareño puede variar, intra e interespecíficamente, por factores bióticos y abióticos. En este trabajo se estudió el ámbito hogareño de la lagartija partenogenética Aspidoscelis cozumela,una especie de forrajeo amplio, con alta preferencia por las playas y microendémica de Isla Cozumel, México. El ámbito hogareño de A. cozumelase comparó con otras especies de Aspidoscelis(gonocóricas y partenogenéticas) y con otras lagartijas que ocupan hábitats costeros. Además, se discuten los factores bióticos y abióticos que lo moldean. La zona de estudio fue una playa (con un área de 4 000 m2), que se encuentra al Este de la isla y que presenta vegetación halófita (expuesta a altos niveles de insolación). De 1999 al 2001 se realizaron nueve censos que cubrieron la época de sequía, de lluvias y la época de "nortes" de la zona y la temporada de reproducción de A. cozumela.Durante cada censo, se realizó captura-marcaje-recaptura y se registró: fecha, hora del día, longitud hocico-cloaca (LHC) al milímetro más cercano. Los individuos fueron ubicados en el área de estudio por bi-coordenadas usando estacas como referencia. El ámbito hogareño se calculó con el método del polígono convexo con el programa McPaal, adicional-mente se calculó el solapamiento del ámbito hogareño. Se relacionó la LHC con el ámbito hogareño. Para el cálculo del ámbito hogareño se consideraron las hembras con tres o más recapturas. Se obtuvieron 20 ámbitos hogareños, que promediaron 45.1 ± 14.0 m2. No se encontró relación de la LHC con el ámbito hogareño (p = 0.9229, n = 20). Sin embargo, un análisis que excluyó los individuos con los ámbitos hogareños extremos, mostró que el ámbito hogareño de A. cozumelase relacionó de manera positiva con la LHC (p = 0.0072, n = 18), las hembras más grandes tuvieron ámbitos hogareños más amplios. El solapamiento del ámbito hogareño fue de 22.9 ± 5.7%. El ámbito hogareño de A. cozumelaes el más pequeño que se ha documentado en el género Aspidoscelis(incluyendo especies partenoge-néticas y gonocóricas) y se contrapone con las predicciones teóricas que establecen ámbitos hogareños amplios para especies de forrajeo amplio. Beneficios térmicos y una elevada densidad poblacional pueden explicar la marcada residencia en las playas y ámbito hogareño reducido de A. cozumela.La lagartija partenogenética A. cozumelaestá bien adaptada a las condiciones ambientales en las playas, sin embargo las afectaciones severas en las playas por el desarrollo de la infraestructura turística pueden poner en riesgo su existencia en Isla Cozumel.

Seasonal spermatogenesis in the Mexican endemic oviparous lizard, Sceloporus aeneus (Squamata: Phrynosomatidae).

Oviparous species of Sceloporus exhibit either seasonal or continuous spermatogenesis and populations from high-elevation show a seasonal pattern known as spring reproductive activity. We studied the spermatogenic cycle of a high-elevation (2700 m) population of endemic oviparous lizard, Sceloporus aeneus, that resided south of México, D.F. Histological analyses were performed on the testes and reproductive ducts from individual lizards collected monthly. This population of S. aeneus showed a seasonal pattern of spermatogenesis, with 4 successive phases common in other lizards. These include: 1) Quiescence in August, which contained solely spermatogonia and Sertoli cells; 2) Testicular recrudescence (September-January) when testes became active with mitotic spermatogonia, spermatocytes beginning meiosis, and the early stages of spermiogenesis with spermatids; 3) Maximum testicular activity occurred from March to May and is when the largest spermiation events ensued within the germinal epithelia, which were also dominated by spermatids and spermiogenic cells; 4) Testicular regression in June was marked with the number of all germs cells decreasing rapidly and spermatogonia dominated the seminiferous epithelium. February was a transitional month between recrudescence and maximum activity. The highest sperm abundance in the lumina of epididymides was during maximum testicular activity (March-May). Thus, before and after these months fewer spermatozoa were detected within the excurrent ducts as the testis transitions from recrudescence to maximum activity in February and from maximum activity to quiescence in June. Maximum spermatogenic activity corresponds with warmest temperatures at this study site. This pattern known as spring reproductive activity with a fall recrudescence was similar to other oviparous species of genus Sceloporus.

The ultrastructure of spermatid development during spermiogenesis within the rosebelly lizard, Sceloporus variabilis (Reptilia, Squamata, Phrynosomatidae).

Several recent studies have mapped out the characters of spermiogenesis within several species of squamates. Many of these data have shown both conserved and possibly apomorphic morphological traits that could be important in future phylogenetic analysis within Reptilia. There, however, has not been a recent study that compares spermiogenesis and its similarities or differences between two species of reptile that reside in the same genus. Thus, the present analysis details the changes to spermiogenesis in Sceloporus variabilis and then compares spermatid morphologies to that of Sceloporus bicanthalis. Many of the morphological changes that the spermatids undergo in these two species are similar or conserved, which is similar to what has been reported in other squamates. There are six main character differences that can be observed during the development of the spermatids between these two sceloporid lizards. They include the presence (S. variabilis) or absence (S. bicanthalis) of a mitochondrial/endoplasmic reticulum complex near the Golgi apparatus during acrosome development, a shallow (S. variabilis) or deep (S. bicanthalis) nuclear indentation that accommodates the acrosomal vesicle, filamentous (S. variabilis) or granular (S. bicanthalis) chromatin condensation, no spiraling (S. variabilis) or spiraling (S. bicanthalis) of chromatin during condensation, absence (S. variabilis) or presence (S. bicanthalis) of the longitudinal manchette microtubules, and the lack of (S. variabilis) or presence (S. bicanthalis) of nuclear lacunae. This is the first study that compares spermiogenic ultrastructural characters between species within the same genus. The significance of the six character differences between two distantly related species within Sceloporus is still unknown, but these data do suggest that spermiogenesis might be a good model to study the hypothesis that spermatid ontogeny is species specific.

Spermiogenesis in the imbricate alligator lizard, Barisia imbricata (Reptilia, Squamata, Anguidae).

Although the events of spermiogenesis are commonly studied in amniotes, the amount of research available for Squamata is lacking. Many studies have described the morphological characteristics of mature spermatozoa in squamates, but few detail the ultrastructural changes that occur during spermiogenesis. This study's purpose is to gain a better understanding of the subcellular events of spermatid development within the Imbricate Alligator Lizard, Barisia imbricata. The morphological data presented here represent the first complete ultrastructural study of spermiogenesis within the family Anguidae. Samples of testes from four specimens collected on the northwest side of the Nevado de Toluca, México, were prepared using standard techniques for transmission electron microscopy. Many of the ultrastructural changes occurring during spermiogenesis within B. imbricata are similar to that of other squamates (i.e., early acrosome formation, chromatin condensation, flagella formation, annulus present, and a prominent manchette). However, there are a few unique characteristics within B. imbricata spermatids that to date have not been described during spermiogenesis in other squamates. For example, penetration of the acrosomal granule into the subacrosomal space to form the basal plate of the perforatorium during round spermatid development, the clover-shaped morphology of the developing nuclear fossa of the flagellum, and the bulbous shape to the perforatorium are all unique to the Imbricate Alligator Lizard. These anatomical character differences may be valuable nontraditional data that along with more traditional matrices (such as DNA sequences and gross morphological data) may help elucidate phylogenetic relationships, which are historically considered controversial within Squamata.

Ontogenic development of spermatids during spermiogenesis in the high altitude bunchgrass lizard (Sceloporus bicanthalis).

The body of ultrastructural data on spermatid characters during spermiogenesis continues to grow in reptiles, but is still relatively limited within the squamates. This study focuses on the ontogenic events of spermiogenesis within a viviparous and continually spermatogenic lizard, from high altitude in Mexico. Between the months of June and August, testicular tissues were collected from eight spermatogenically active bunchgrass lizards (Sceloporus bicanthalis) from Nevado de Toluca, México. The testicular tissues were processed for transmission electron microscopy and analyzed to access the ultrastructural differences between spermatid generations during spermiogenesis. Interestingly, few differences exist between S. bicanthalis spermiogenesis when compared with what has been described for other saurian squamates. Degrading and coiling membrane structures similar to myelin figures were visible within the developing acrosome that are likely remnants from Golgi body vesicles. During spermiogenesis, an electron lucent area between the subacrosomal space and the acrosomal medulla was observed, which has been observed in other squamates but not accurately described. Thus, we elect to term this region the acrosomal lucent ridge. This study furthers the existing knowledge of spermatid development in squamates, which could be useful in future work on the reproductive systems in high altitude viviparous lizard species.

[Seasonal changes in the dorsal coloration in the lizard Aspidoscelis costata costata (Squamata: Teiidae)]. / Cambio estacional en la coloración dorsal de la lagartija Aspidoscelis costata costata (Squamata: Teiidae).

Color and color patterns in animals are important characteristics that bring protection, by dampening the ability of predators that depend on their sight to detect their preys. In lizards, the dorsal coloration plays a key role in communication of intraspecific signals such as social cues. In this study, we evaluated the seasonal changes in the dorsal coloration of the wide foraging lizard A. costata costata, in Tonatico, State of Mexico, Mexico. The seasonal evaluation included: the rainy season from mid June to mid September (can also include the end of May to early October); and the dry season for the rest of the year. The dorsal coloration of A. costata costata and their microhabitats were evaluated by contrasting the color pattern with an identification guide and the control colors of Pantone, during 11 samplings carried out from February-October 2007. Individual lizard analysis recorded snout-vent length, sex and stage (juveniles and adults). Besides, all animals were marked by toe-clipping, allowing to distinguish dorsal coloration between seasons, sex and stage. A total of 95 lizards were analyzed (53 and 42 for the dry and rainy seasons respectively). We found that the dorsal coloration in A. costata costata varies seasonally and with microhabitats: during the dry season individuals show a brown coloration whereas during the rainy season becomes greener, as the background dominant vegetation color. The results of the present study suggest that: 1) the variation in dorsal coloration in A. costata costata plays an important role in the survival (by cryptic camouflage) of this widely foraging species; 2) the changes in the dorsal coloration of A. costata costata are individually expressed traits, since the coloration of the same lizard is either brown or green depending on the season; and 3) the cryptic functions of the dorsal coloration in widely foraging species have been largely underestimated. We discuss the possible influence of the changes in coloration in an habitat that changes drastically between both dry and rainy seasons.

Cambio estacional en la coloración dorsal de la lagartija Aspidoscelis costata costata (Squamata: Teiidae) / Seasonal changes in the dorsal coloration in the lizard Aspidoscelis costata costata (Squamata: Teiidae)

Seasonal changes in the dorsal coloration in the lizard Aspidoscelis costata costata (Squamata: Teiidae). Color and color patterns in animals are important characteristics that bring protection, by dampening the ability of predators that depend on their sight to detect their preys. In lizards, the dorsal coloration plays a key role in communication of intraspecific signals such as social cues. In this study, we evaluated the seasonal changes in the dorsal coloration of the wide foraging lizard A. costata costata, in Tonatico, State of Mexico, Mexico. The seasonal evaluation included: the rainy season from mid June to mid September (can also include the end of May to early October); and the dry season for the rest of the year. The dorsal coloration of A. costata costata and their microhabitats were evaluated by contrasting the color pattern with an identification guide and the control colors of Pantone®, during 11 samplings carried out from February-October 2007. Individual lizard analysis recorded snout-vent length, sex and stage (juveniles and adults). Besides, all animals were marked by toe-clipping, allowing to distinguish dorsal coloration between seasons, sex and stage. A total of 95 lizards were analyzed (53 and 42 for the dry and rainy seasons respectively). We found that the dorsal coloration in A. costata costata varies seasonally and with microhabitats: during the dry season individuals show a brown coloration whereas during the rainy season becomes greener, as the background dominant vegetation color. The results of the present study suggest that: 1) the variation in dorsal coloration in A. costata costata plays an important role in the survival (by cryptic camouflage) of this widely foraging species; 2) the changes in the dorsal coloration of A. costata costata are individually expressed traits, since the coloration of the same lizard is either brown or green depending on the season; and 3) the cryptic functions of the dorsal coloration in widely foraging species have been largely underestimated. We discuss the possible influence of the changes in coloration in an habitat that changes drastically between both dry and rainy seasons.

En lagartijas la coloración corporal es importanteen la comunicación así como en la protección contra los depredadores. Con el uso de una guía Pantone®, se analizó el cambio estacional en la coloración dorsal y los microhábitats de Aspidoscelis costata costata, una lagartija de amplio forrajeo que habita un ambiente (en el Estado de México, México) que cambia drásticamente de apariencia entre sequía y lluvias. Se analizó la dependencia de la coloración dorsal de acuerdo a la estación, sexo y estadio de desarrollo. Los resultados indican que la lagartija A. costata costata presenta una coloración dorsal similar al sustrato en cada estación: parda en sequía y principalmente verde en lluvias. Este estudio sugiere: 1) Que la variación en coloración dorsal con funciones crípticas, como la registrada en A. costata costata, puede resultar importante en la supervivencia de especies de amplio forrajeo; 2) Que el cambio en la coloración dorsal en A. costata costata es a nivel individual, ya que un individuo presente en ambas estaciones manifiesta una coloración dorsal parda en la estación de sequía y una coloración dorsal verde en la estación de lluvias y 3) Que la coloración dorsal, con funciones crípticas, está subestimada en especies de amplio forrajeo.

Temporal germ cell development strategy during continuous spermatogenesis within the montane lizard, Sceloporus bicanthalis (Squamata; Phrynosomatidae).

Sceloporus bicanthalis is a viviparous lizard that lives at higher elevations in Mexico. Adult male S. bicanthalis were collected (n = 36) from the Nevado de Toluca, Mexico (elevation is 4200 m) during August to December, 2007 and January to July, 2008. Testes were extracted, fixed in Trumps, and dehydrated in a graded series of ethanol. Tissues were embedded, sectioned (2 µm), stained, and examined via a light microscope to determine the spermatogenic developmental strategy of S. bicanthalis. In all months examined, the testes were spermiogenically active; based on this, plus the presence of sperm in the lumina of seminiferous tubules, we inferred that S. bicanthalis had year-round or continuous spermatogenesis, unlike most reptiles that occupy a temperate or montane habitat. It was recently reported that seasonally breeding reptiles had a temporal germ cell development strategy similar to amphibians, where germ cells progress through spermatogenesis as a single population, which leads to a single spermiation event. This was much different than spatial development within the testis of other derived amniotes. We hypothesized that germ cell development was temporal in S. bicanthalis. Therefore, we wanted to determine whether reptiles that practice continuous spermatogenesis have a mammalian-like spatial germ cell development, which is different than the typical temperate reptile exhibiting a temporal development. In the present study, S. bicanthalis had a temporal development strategy, despite its continuous spermatogenic cycle, making them similar to tropical anoles.

Larval stages of trematodes in gastropods from Lake Chicnahuapan, State of Mexico, Mexico.

During the period from January to December (2007), 1,095 freshwater molluscs of four species were captured (Lymnaea stagnalis, Stagnicola elodes, Physella cubensis and Physa acuta) in Lake Chicnahuapan, State of Mexico, Mexico. Two hundred seventy-two (24.84% prevalence) of these molluscs were parasitised by 11 trematode species (from which two were not identified at the species level) having six cercariae species and five metacercariae species represented in five families. The cercariae Telorchis corti (Plagiorchiidae) and the metacercariae Cotylurus cornutus (Strigeidae) were the species with the highest prevalence among the examined snails. The highest percentage of infection was observed in L. stagnalis (27.45% of prevalence, n = 572) and P. cubensis (23.96%, n = 455). Twenty-one of the examined snails had multiple infections with up to three trematode species.

Variación morfológica de la lagartija partenogenética Aspidoscelis rodecki (Squamata: Teiidae): implicaciones evolutivas y de conservación

Morphologic variation of the parthenogenetic lizard Aspidoscelis rodecki (Squamata: Teiidae): evolutionary and conservation implications. Post-formational divergence has been used for the recognition of new parthenogenetic species. Currently, the parthenogenetic lizard Aspidoscelis rodecki McCoy and Maslin 1962 is recognized as a single taxon that was derived from a single, parthenogenetically capable, hybrid. This lizard had been derived via hybridization between individuals of two gonochoristic species, Aspidoscelis angusticeps Cope 1878 and Aspidoscelis deppii Wiegmann 1834. The distribution of A. rodecki includes Isla Contoy and Isla Mujeres and the adjacent mainland of Quintana Roo, México. Previous studies have found post-formational divergence in genetic, chromatic and life-history characteristics among a continental population (Puerto Juárez) and an insular population (Isla Contoy). A meristic analysis was carried out to evaluate the morphological divergence among both populations of A. rodecki. We used 38 individuals from Puerto Juárez and 23 individuals from Isla Contoy. Nine meristic characters with discrimination value among species of the genus Aspidoscelis were used in both univariate (t-Student) and multivariate analyses (principal components and canonical variate analysis). According to both analyses, Puerto Juárez is meristically distinguishable from Isla Contoy. Both populations differ in five meristic characters and were a high correct classification in the canonical variate analysis: 97% of Puerto Juárez and 100% of Isla Contoy. A small sample from Isla Mujeres and a single specimen from Punta Sam (mainland) may represent different morphological groups. Due to the patterns of phenotypic variation, A. rodecki is considered as a single variable parthenogenetic species with high priority to conservation. The populations of A. rodecki have been extremely affected by the tourism developers. If the habitat of the parthenogenetic lizard (beach grasses) is allowed to stay, the expansion by the developers will not affect the survivorship of these populations. Nevertheless, the first sign of development is the total destruction of natural grasses that occurs on the beach, leaving only sand. There is a last chance to save the parthenogenetic lizard A. rodecki, but any effort will be useless without the support from the environmental authority of Mexico and cooperation from the developers. We suggest that Puerto Juárez and Isla Contoy receive separate management because they have unique portions of phenotypic variation of A. rodecki. The two lizard populations can be considered separate "Evolutionary Significant Units" (ESU). Rev. Biol. Trop. 56 (4): 1871-1881. Epub 2008 December 12.

La divergencia post-formación se ha utilizado para el reconocimiento de nuevas especies partenogenéticas. Actualmente, la lagartija partenogenética Aspidoscelis rodecki McCoy y Maslin 1962 es reconocida como una sola especie, que se originó de un híbrido partenogenético. Estudios previos han encontrado divergencia genética, en coloración y en características de historia de vida entre una población continental (Puerto Juárez) y una insular (Isla Contoy) en Quintana Roo, México. Se llevó a cabo un análisis merístico para evaluar la divergencia entre ambas poblaciones de A. rodecki. Se utilizaron 38 individuos de Puerto Juárez y 23 individuos de Isla Contoy. Se usaron nueve características merísticas y se realizaron análisis univariados (t de Student) y multivariados (análisis de componentes principales y análisis de variación canónica). De acuerdo a ambos análisis, Puerto Juárez es merísticamente distinguible de Isla Contoy. Ambas poblaciones difieren en cinco características merísticas y presentaron un alto porcentaje de clasificación en el análisis de variación canónica: 97% para Puerto Juárez y 100% para Isla Contoy. Una pequeña muestra de Isla Mujeres y un solo individuo de Punta Sam (continente) pueden representar otros grupos morfológicos. Con base en los patrones de variación fenotípica, A. rodecki es considerada como una sola especie partenogenética variable y prioritaria para la conservación. Debido a que cada población contiene una porción única de la variación de A. rodecki, Puerto Juárez e Isla Contoy merecen un manejo separado y se sugiere que cada una constituya una "Unidad Evolutiva Significativa" (ESU).

[Morphologic variation of the parthenogenetic lizard Aspidoscelis rodecki (Squamata: Teiidae): evolutionary and conservation implications]. / Variación morfológica de la lagartija partenogenética Aspidoscelis rodecki (Squamata: Teiidae): implicaciones evolutivas y de conservación.

Post-formational divergence has been used for the recognition of new parthenogenetic species. Currently, the parthenogenetic lizard Aspidoscelis rodecki McCoy and Maslin 1962 is recognized as a single taxon that was derived from a single, parthenogenetically capable, hybrid. This lizard had been derived via hybridization between individuals of two gonochoristic species, Aspidoscelis ungusticeps Cope 1878 and Aspidoscelis deppii Wiegmann 1834. The distribution of A. rodecki includes Isla Contoy and Isla Mujeres and the adjacent mainland of Quintana Roo, México. Previous studies have found post-formational divergence in genetic, chromatic and life-history characteristics among a continental population (Puerto Juárez) and an insular population (Isla Contoy). A meristic analysis was carried out to evaluate the morphological divergence among both populations of A. rodecki. We used 38 individuals from Puerto Juárez and 23 individuals from Isla Contoy. Nine meristic characters with discrimination value among species of the genus Aspidoscelis were used in both univariate (t-Student) and multivariate analyses (principal components and canonical variate analysis). According to both analyses, Puerto Juárez is meristically distinguishable from Isla Contoy. Both populations differ in five meristic characters and were a high correct classification in the canonical variate analysis: 97% of Puerto Juárez and 100% of Isla Contoy. A small sample from Isla Mujeres and a single specimen from Punta Sam (mainland) may represent different morphological groups. Due to the patterns of phenotypic variation, A. rodecki is considered as a single variable parthenogenetic species with high priority to conservation. The populations of A. rodecki have been extremely affected by the tourism developers. If the habitat of the parthenogenetic lizard (beach grasses) is allowed to stay, the expansion by the developers will not affect the survivorship of these populations. Nevertheless, the first sign of development is the total destruction of natural grasses that occurs on the beach, leaving only sand. There is a last chance to save the parthenogenetic lizard A. rodecki, but any effort will be useless without the support from the environmental authority of Mexico and cooperation from the developers. We suggest that Puerto Juárez and Isla Contoy receive separate management because they have unique portions of phenotypic variation of A. rodecki. The two lizard populations can be considered separate "Evolutionary Significant Units" (ESU).