RESUMO
BACKGROUND: Environmental conditions on Earth are repeated in non-random patterns that often coincide with species from different regions and time periods having consistent combinations of morphological, physiological and behavioral traits. Observation of repeated trait combinations among species confronting similar environmental conditions suggest that adaptive trait combinations are constrained by functional tradeoffs within or across niche dimensions. In an earlier study, we assembled a high-resolution database of functional traits for 134 lizard species to explore ecological diversification in relation to five fundamental niche dimensions. Here we expand and further examine multivariate relationships in that dataset to assess the relative influence of niche dimensions on the distribution of species in 6-dimensional niche space and how these may deviate from distributions generated from null models. We then analyzed a dataset with lower functional-trait resolution for 1023 lizard species that was compiled from our dataset and a published database, representing most of the extant families and environmental conditions occupied by lizards globally. Ordinations from multivariate analysis were compared with null models to assess how ecological and historical factors have resulted in the conservation, divergence or convergence of lizard niches. RESULTS: Lizard species clustered within a functional niche volume influenced mostly by functional traits associated with diet, activity, and habitat/substrate. Consistent patterns of trait combinations within and among niche dimensions yielded 24 functional groups that occupied a total niche space significantly smaller than plausible spaces projected by null models. Null model tests indicated that several functional groups are strongly constrained by phylogeny, such as nocturnality in the Gekkota and the secondarily acquired sit-and-wait foraging strategy in Iguania. Most of the widely distributed and species-rich families contained multiple functional groups thereby contributing to high incidence of niche convergence. CONCLUSIONS: Comparison of empirical patterns with those generated by null models suggests that ecological filters promote limited sets of trait combinations, especially where similar conditions occur, reflecting both niche convergence and conservatism. Widespread patterns of niche convergence following ancestral niche diversification support the idea that lizard niches are defined by trait-function relationships and interactions with environment that are, to some degree, predictable and independent of phylogeny.
Assuntos
Lagartos , Animais , Evolução Biológica , Ecossistema , Humanos , Fenótipo , FilogeniaRESUMO
No central online repository exists for the collection of animal images; hence it remains unclear how extensively species have been illustrated in the published literature or online. Here we compiled a list of more than 8000 reptile species (out of 11,341) that have photos in one of six popular online repositories, namely iNaturalist (6,349 species), the Reptile Database (5,144), Flickr (4,386), CalPhotos (3,071), Wikimedia (2,952), and Herpmapper (2,571). These sites have compiled over one million reptile photos, with some species represented by tens of thousands of images. Despite the number of images, many species have only one or a few images. This suggests that a considerable fraction of morphological and geographic variation is under documented or difficult to access. We highlight prominent gaps in amphisbaenians, lizards, and snakes, with geographic hotspots for species without images in Central Africa, Pacific Islands, and the Andes Mountains. We present a list of ~3,000 species without photos in any of the six databases and ask the community to fill the gaps by depositing images on one of these sites (preferably with minimal copyright restrictions).
RESUMO
Amazonia harbors the greatest biological diversity on Earth. One trend that spans Amazonian taxa is that most taxonomic groups either exhibit broad geographic ranges or small restricted ranges. This is likely because many traits that determine a species range size, such as dispersal ability or body size, are autocorrelated. As such, it is rare to find groups that exhibit both large and small ranges. Once identified, however, these groups provide a powerful system for isolating specific traits that influence species distributions. One group of terrestrial vertebrates, gecko lizards, tends to exhibit small geographic ranges. Despite one exception, this applies to the Neotropical dwarf geckos of the genus Gonatodes. This exception, Gonatodes humeralis, has a geographic distribution almost 1,000,000â¯km2 larger than the combined ranges of its 30 congeners. As the smallest member of its genus and a gecko lizard more generally, G. humeralis is an unlikely candidate to be a wide-ranged Amazonian taxon. To test whether or not G. humeralis is one or more species, we generated molecular genetic data using restriction-site associated sequencing (RADseq) and traditional Sanger methods for samples from across its range and conducted a phylogeographic study. We conclude that G. humeralis is, in fact, a single species across its contiguous range in South America. Thus, Gonatodes is a unique clade among Neotropical taxa, containing both wide-ranged and range-restricted taxa, which provides empiricists with a powerful model system to correlate complex species traits and distributions. Additionally, we provide evidence to support species-level divergence of the allopatric population from Trinidad and we resurrect the name Gonatodes ferrugineus from synonymy for this population.
Assuntos
Lagartos/classificação , Animais , Genética Populacional , Lagartos/genética , Filogenia , Filogeografia , América do SulRESUMO
We summarize thermal-biology data of 69 species of Amazonian lizards, including mode of thermoregulation and field-active body temperatures (Tb). We also provide new data on preferred temperatures (Tpref), voluntary and thermal-tolerance ranges, and thermal-performance curves (TPC's) for 27 species from nine sites in the Brazilian Amazonia. We tested for phylogenetic signal and pairwise correlations among thermal traits. We found that species generally categorized as thermoregulators have the highest mean values for all thermal traits, and broader ranges for Tb, critical thermal maximum (CTmax) and optimal (Topt) temperatures. Species generally categorized as thermoconformers have large ranges for Tpref, critical thermal minimum (CTmin), and minimum voluntary (VTmin) temperatures for performance. Despite these differences, our results show that all thermal characteristics overlap between both groups and suggest that Amazonian lizards do not fit into discrete thermoregulatory categories. The traits are all correlated, with the exceptions of (1) Topt, which does not correlate with CTmax, and (2) CTmin, and correlates only with Topt. Weak phylogenetic signals for Tb, Tpref and VTmin indicate that these characters may be shaped by local environmental conditions and influenced by phylogeny. We found that open-habitat species perform well under present environmental conditions, without experiencing detectable thermal stress from high environmental temperatures induced in lab experiments. For forest-dwelling lizards, we expect warming trends in Amazonia to induce thermal stress, as temperatures surpass the thermal tolerances for these species.
Assuntos
Aclimatação/fisiologia , Regulação da Temperatura Corporal/fisiologia , Temperatura Corporal/fisiologia , Lagartos/fisiologia , Temperatura , Animais , Brasil , Ecossistema , Geografia , Lagartos/classificação , Especificidade da EspécieRESUMO
Inferring the evolutionary and biogeographic history of taxa occurring in a particular region is one way to determine the processes by which the biodiversity of that region originated. Tree boas of the genus Corallus are an ancient clade and occur throughout Central and South America and the Lesser Antilles, making it an excellent group for investigating Neotropical biogeography. Using sequenced portions of two mitochondrial and three nuclear loci for individuals of all recognized species of Corallus, we infer phylogenetic relationships, present the first molecular analysis of the phylogenetic placement of the enigmatic C. cropanii, develop a time-calibrated phylogeny, and explore the biogeographic history of the genus. We found that Corallus diversified within mainland South America, via over-water dispersals to the Lesser Antilles and Central America, and via the traditionally recognized Panamanian land bridge. Divergence time estimates reject the South American Caribbean-Track as a general biogeographic model for Corallus and implicate a role for events during the Oligocene and Miocene in diversification such as marine incursions and the uplift of the Andes. Our findings also suggest that recognition of the island endemic species, C. grenadensis and C. cookii, is questionable as they are nested within the widely distributed species, C. hortulanus. Our results highlight the importance of using widespread taxa when forming and testing biogeographic hypotheses in complex regions and further illustrate the difficulty of forming broadly applicable hypotheses regarding patterns of diversification in the Neotropical region.
Assuntos
Distribuição Animal , Boidae/classificação , Boidae/genética , Evolução Molecular , Filogenia , Animais , Sequência de Bases , Teorema de Bayes , América Central , Primers do DNA/genética , Funções Verossimilhança , Modelos Genéticos , Dados de Sequência Molecular , Filogeografia , Análise de Sequência de DNA , América do SulRESUMO
Alaeuris rinconensis n. sp. (Oxyuroidea, Pharyngodonidae) from the large intestine of the Bonaire whiptail lizard, Cnemidophorus ruthveni, is described and illustrated. Alaeuris rinconensis n. sp. represents the 13th Neotropical species assigned to the genus. It is most similar to Alaeuris iguanae in that only these 2 Neotropical species have postbulbar excretory pores; in A. iguanae, a tail filament is absent; in A. rinconensis, a tail filament is present. Two additional helminth species were found, i.e., the cestode Oochoristica iguanae and a nematode, Ozolaimus megatyphlon. Cnemidoporus ruthveni represents a new host record for the latter 2 species.
Assuntos
Lagartos/parasitologia , Oxiuríase/veterinária , Oxyuroidea/classificação , Animais , Feminino , Masculino , Antilhas Holandesas , Oxiuríase/parasitologia , Oxyuroidea/anatomia & histologiaRESUMO
Biological impacts of climate warming are predicted to increase with latitude, paralleling increases in warming. However, the magnitude of impacts depends not only on the degree of warming but also on the number of species at risk, their physiological sensitivity to warming and their options for behavioural and physiological compensation. Lizards are useful for evaluating risks of warming because their thermal biology is well studied. We conducted macrophysiological analyses of diurnal lizards from diverse latitudes plus focal species analyses of Puerto Rican Anolis and Sphaerodactyus. Although tropical lowland lizards live in environments that are warm all year, macrophysiological analyses indicate that some tropical lineages (thermoconformers that live in forests) are active at low body temperature and are intolerant of warm temperatures. Focal species analyses show that some tropical forest lizards were already experiencing stressful body temperatures in summer when studied several decades ago. Simulations suggest that warming will not only further depress their physiological performance in summer, but will also enable warm-adapted, open-habitat competitors and predators to invade forests. Forest lizards are key components of tropical ecosystems, but appear vulnerable to the cascading physiological and ecological effects of climate warming, even though rates of tropical warming may be relatively low.
Assuntos
Aclimatação , Efeito Estufa , Lagartos/fisiologia , Clima Tropical , Animais , Temperatura Corporal , Ecossistema , Geografia , Lagartos/classificação , Filogenia , Porto Rico , TemperaturaRESUMO
The niche expansion and niche variation hypotheses predict that release from interspecific competition will promote niche expansion in depauperate assemblages. Niche expansion can occur by different mechanisms, including an increase in within-individual, among-individual, or bimodal variation (sexual dimorphism). Here we explore whether populations with larger niche breadth have a higher degree of diet variation. We also test whether populations from depauperate lizard assemblages differ in dietary resource use with respect to variation within and/or among individuals and sexual dimorphism. We found support for the niche expansion and niche variation hypotheses. Populations in assemblages with low phylogenetic diversity had a higher degree of individual variation, suggesting a tendency for niche expansion. We also found evidence suggesting that the mechanism causing niche expansion is an increase in variation among individuals rather than an increase in within-individual variation or an increase in bimodal variation due to sexual dimorphism.
Assuntos
Adaptação Biológica/fisiologia , Dieta , Ecossistema , Lagartos/fisiologia , Modelos Teóricos , Caracteres Sexuais , Animais , Brasil , Análise de Regressão , Especificidade da EspécieRESUMO
The genus Gonatodes is a monophyletic group of small-bodied, diurnal geckos distributed across northern South America, Central America, and the Caribbean. We used fragments of three nuclear genes (RAG2, ACM4, and c-mos) and one mitochondrial gene (16S) to estimate phylogenetic relationships among Amazonian species of Gonatodes. We used Penalized Likelihood to estimate timing of diversification in the genus. Most cladogenesis occurred in the Oligocene and early Miocene and coincided with a burst of diversification in other South American animal groups including mollusks, birds, and mammals. The Oligocene and early Miocene were periods dominated by dramatic climate change and Andean orogeny and we suggest that these factors drove the burst of cladogenesis in Gonatodes geckos as well as other taxa. A common pattern in Amazonian taxa is a biogeographic split between the eastern and western Amazon basin. We observed two clades with this spatial distribution, although large differences in timing of divergence between the east-west taxon pairs indicate that these divergences were not the result of a common vicariant event.
Assuntos
Clima , Especiação Genética , Lagartos/classificação , Lagartos/genética , Animais , Núcleo Celular/genética , Genes Mitocondriais/genética , Variação Genética , Filogenia , Análise de Sequência de DNA , América do SulRESUMO
Rhabdias nicaraguensis n. sp. (Rhabditida: Rhabditidae) from the lungs of Norops capito (Sauria: Polychrotidae) is described and illustrated. Rhabdias nicaraguensis n. sp. represents the 54th species assigned to the genus and the 12th from the Neotropical realm. Of the 12 Neotropical Rhabdias species, nicaraguensis is most similar to tobagoensis and vellardi. These 3 species have equatorial placement of the vulva, inflated cuticle, and 6 small circumoral lips. Rhabdias nicaraguensis is easily separated from R. tobagoensis by the shape of the buccal cavity and from R. vellardi by body size and shape of the tail. Rhabdias nicaraguensis differs from both species by host preference, the amount of inflated cuticle covering the body, and the phasmids situated posterior to the midpoint of the tail.
Assuntos
Lagartos/parasitologia , Pneumopatias Parasitárias/veterinária , Infecções por Rhabditida/veterinária , Rhabditoidea/classificação , Acantocéfalos/classificação , Acantocéfalos/isolamento & purificação , Animais , Feminino , Helmintíase Animal/epidemiologia , Helmintíase Animal/parasitologia , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Enteropatias Parasitárias/veterinária , Intestino Delgado/parasitologia , Pneumopatias Parasitárias/epidemiologia , Pneumopatias Parasitárias/parasitologia , Masculino , Infecções por Nematoides/epidemiologia , Infecções por Nematoides/parasitologia , Infecções por Nematoides/veterinária , Nicarágua , Prevalência , Infecções por Rhabditida/epidemiologia , Infecções por Rhabditida/parasitologia , Rhabditoidea/anatomia & histologia , Rhabditoidea/isolamento & purificaçãoRESUMO
We compare lizard assemblages of Cerrado and Amazonian savannas to test the ecological release hypothesis, which predicts that niche dimensions and abundance should be greater in species inhabiting isolated habitat patches with low species richness (Amazonian savannas and isolated Cerrado patches) when compared with nonisolated areas in central Cerrado with greater species richness. We calculated microhabitat and diet niche breadths with data from 14 isolated Cerrado patches and Amazon savanna areas and six central Cerrado populations. Morphological data were compared using average Euclidean distances, and lizard abundance was estimated using the number of lizards captured in pitfall traps over an extended time period. We found no evidence of ecological release with respect to microhabitat use, suggesting that historical factors are better microhabitat predictors than ecological factors. However, data from individual stomachs indicate that ecological release occurs in these areas for one species (Tropidurus) but not others (Ameiva ameiva, Anolis, Cnemidophorus, and Micrablepharus), suggesting that evolutionary lineages respond differently to environmental pressures, with tropidurids being more affected by ecological factors than polychrotids, teiids, and gymnophthalmids. We found no evidence that ecological release occurs in these areas using morphological data. Based on abundance data, our results indicate that the ecological release (density compensation) hypothesis is not supported: lizard species are not more abundant in isolated areas than in nonisolated areas. The ecology of species is highly conservative, varying little from assemblage to assemblage. Nevertheless, increases in niche breadth for some species indicate that ecological release occurs as well.
Assuntos
Ecossistema , Lagartos/fisiologia , Animais , Demografia , Modelos Biológicos , Especificidade da EspécieRESUMO
Oswaldocruzia nicaraguensis n. sp. (Strongylida: Molineidae) from the intestines of Ameiva festiva (Sauria: Teiidae) is described and illustrated. Oswaldocruzia nicaraguensis represents the 78th species assigned to the genus and is most similar to the Caribbean species of the genus by possessing spicules in which each of the 3 divisions terminates in numerous fine points. Of the 8 species assigned to this group, O. nicaraguensis is most similar to Oswaldocruzia moraveci; of the 8 species, only O. moraveci and O. nicaraguensis possess a type II bursa and lack cervical alae. It is separated from O. moraveci by the position of the tips of ribs 5-6; close together in O. nicaraguensis, well separated in O. moraveci.
Assuntos
Lagartos/parasitologia , Infecções por Strongylida/veterinária , Estrongilídios/classificação , Animais , Feminino , Masculino , Nicarágua , Estrongilídios/anatomia & histologia , Infecções por Strongylida/parasitologiaRESUMO
Allopharynx daileyi n. sp. (Digenea: Plagiorchiidae) from the small intestine of the tropidurid lizard Uranoscodon superciliosus from Amazonian Brazil is described and illustrated. Of the 11 currently recognized species of Allopharynx, we consider Allopharynx megorchis Simha, 1961 a synonym of Allopharynx mehrai (Gogate, 1935) Price 1938 and Allopharynx puertoricensis Acholonu, 1976 a synonym of Allopharynx riopedrensis Garcia-Diaz; thus, A. daileyi becomes the 10th species assigned to the genus. The trematode species Mesocoelium monas and 2 species of Nematoda, Africana chabaudi and Cosmocerca vrcibradici, were also present.
Assuntos
Enteropatias Parasitárias/veterinária , Lagartos/parasitologia , Trematódeos/classificação , Infecções por Trematódeos/veterinária , Animais , Brasil/epidemiologia , Feminino , Enteropatias Parasitárias/epidemiologia , Enteropatias Parasitárias/parasitologia , Intestino Delgado/parasitologia , Masculino , Trematódeos/anatomia & histologia , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/parasitologiaRESUMO
New World skinks of the genus Mabuya exhibit a unique form of viviparity that involves ovulation of tiny (1 mm) eggs and provision of virtually all of the nutrients for embryonic development by placental means. Studies of the Brazilian species M. heathi reveal that the chorioallantoic placenta is unlike those reported in any other squamate genus and exhibits striking specializations for maternal-fetal nutrient transfer. The uterine lining is intimately apposed to the chorioallantois, with no trace of an intervening shell membrane or of epithelial erosion; thus, the placenta is epitheliochorial. The uterus exhibits multicellular glands that secrete organic material into the uterine lumen. Opposite the openings of these glands, the chorion develops areolae, invaginated pits that are lined by absorptive, columnar epithelium. A single, mesometrial placentome develops, formed by radially oriented uterine folds that project into a deep invagination of the chorion. Uterine epithelium of the placentome appears to be syncytial and secretory and overlies a rich vascular supply. The apposed chorionic epithelium is absorptive in morphology and contains giant binucleated cells that bear microvilli. Several specializations of the placental membranes of M. heathi are found among eutherian mammals, signifying evolutionary convergence that extends to histological and cytological levels. The chorioallantoic placenta of M. heathi and its relatives warrants recognition as a new morphotype for reptiles, defined here as the "Type IV" placenta. This is the first new type of chorioallantoic placenta to be defined formally for reptiles in over half a century.