Aim: Small geographic ranges make species especially prone to extinction from anthropogenic
distu... more Aim: Small geographic ranges make species especially prone to extinction from anthropogenic disturbances or natural stochastic events. We assemble and analyse a comprehensive dataset of all the world’s lizard species and identify the species with the smallest ranges—those known only from their type localities. We compare them to wide-ranging species to infer whether specific geographic regions or biological traits predispose species to have small ranges. Location: Global. Methods: We extensively surveyed museum collections, the primary literature and our own field records to identify all the species of lizards with a maximum linear geographic extent of <10 km. We compared their biogeography, key biological traits and threat status to those of all other lizards. Results: One in seven lizards (927 of the 6,568 currently recognized species) are known only from their type localities. These include 213 species known only from a single specimen. Compared to more wide-ranging taxa, they mostly inhabit relatively inaccessible regions at lower, mostly tropical, latitudes. Surprisingly, we found that burrowing lifestyle is a relatively unimportant driver of small range size. Geckos are especially prone to having tiny ranges, and skinks dominate lists of such species not seen for over 50 years, as well as of species known only from their holotype. Two-thirds of these species have no IUCN assessments, and at least 20 are extinct. Main conclusions: Fourteen per cent of lizard diversity is restricted to a single location, often in inaccessible regions. These species are elusive, usually poorly known and little studied. Many face severe extinction risk, but current knowledge is inadequate to properly assess this for all of them. We recommend that such species become the focus of taxonomic, ecological and survey efforts.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Aim In the New World coral-snake complex, Micrurus species presumably serve as Batesian models fo... more Aim In the New World coral-snake complex, Micrurus species presumably serve as Batesian models for some species of Colubridae, including Oxyrhopus. To better understand the evolutionary role of mimicry, we explored the distributional overlap of Micrurus (models) and Oxyrhopus (mimics), the association between species and pattern richness of both taxa, and the relationship between mimetic fidelity and model diversity. Location The Neotropical region and southern-most Nearctic region. Methods We classified colour patterns and delineated the geographical distributions of species in a 1° grid, spanning the distributions of both genera. We used generalized linear models to test for significant associations of species and colour patterns. We used guided regularized random forests to identify, among Micrurus colour patterns, the best predictors of the presence and richness of Oxyrhopus colour patterns. To account for spatial autocorrelation, we implemented Bayesian hierarchical models using the integral nested Laplace approximation with a conditional autoregressive prior. Results With few exceptions, the presence and richness of species of Micrurus bearing a given colour pattern in grid cells were good predictors of the presence and richness of Oxyrhopus species bearing the same colour pattern. However, these relationships did not hold when we accounted for species of Micrurus bearing different colour patterns, except in a few cases. The presence of perfect (i.e. those that have a matching Micrurus model) and imperfect (those that do not) Oxyrhopus colour patterns in grid cells was positively correlated with the richness of Micrurus colour patterns. Main conclusions Mimicry complexes may not rely upon perfect signal matching and distributional overlap as previously supposed. Tests of mimetic relationships based on geographical distributions must account for alternative hypotheses including organisms that do not appear to be close mimics. Mimicry complexes may capitalize upon model signal diversity, allowing for the diversification of lin-eages with warning coloration in the face of stabilizing selection.
—A central issue in comparative biology is identifying the relative importance of historical (phy... more —A central issue in comparative biology is identifying the relative importance of historical (phylogenetic) versus present-day (ecological) factors in shaping phenotypic traits of organisms. Herein, we investigate effects of sex, ontogeny, and season on diet of Epipedobates flavopictus, a species restricted to open landscapes in central Brazil. Based on prey frequency, number, and volume, the most important prey categories were ants, termites, beetles, spiders, and orthopterans. Prey number and volume increased significantly with snout–vent length (SVL), and the consumption of termites also increased with SVL. There were few effects of sex and season upon diet composition, average prey number, or average prey volume, all independent of SVL. Reproductive females consumed larger prey, in great numbers, likely to increase energy uptake. As is true for most congeners, as well as species of closely related genera, ants are an important component in the diet of E. flavopictus. However, in contrast to its forest relatives, E. flavopictus consumes large amounts of termites, revealing the influence of prevailing ecological conditions. The small volume of ants in the diet of E. flavopictus and the high toxicity of its skin are not in agreement with the hypothesis of a causal relationship between skin toxicity and ant consumption.
This study describes the spermatozoa of the dendrobatids Epipedobates femoralis and Colostethus s... more This study describes the spermatozoa of the dendrobatids Epipedobates femoralis and Colostethus sp. using light and transmission electron microscopy. Both species possess a biflagellate spermatozoon, an unusual characteristic only previously reported in two anuran species belonging to the families Leptodactylidae and Racophoridae. The acrosomal complex of both species consists of a conical acrosomal vesicle and a subacrosomal cone, both of which cover the anterior portion of the nucleus , but to differing extents. In the midpiece, the cen-trioles are disposed parallel to each other and to the cell axis and give rise to two axonemes. Two paraxonemal rods were also seen entering the nuclear fossa. Both flagella are surrounded by a single mitochondrial collar. Each flagellum is formed by an axial fiber connected to the axoneme by an axial sheath; juxta-axonemal fibers are absent. Our data seem to support that Epipedobates femo-ralis should be placed in a separate clade possibly related to Colosthetus and that these two genera may not be monophyletic.
In most amphibians, females are the larger sex presumably due to selection for larger reproductiv... more In most amphibians, females are the larger sex presumably due to selection for larger reproductive output. Sexual selection may, however, produce larger males and also lead to the evolution of secondary sexual characteristics. The proximate causes of sexual dimorphism are related to differences in growth rates and longevity, but these data are scanty for most amphibian species and often depend on long-term demographic studies. Here we use skeletochronology and mark–recapture data obtained on a weekly basis over five years to investigate the sexual dimorphism in body size and shape, growth, and longevity of two toad species, Rhinella rubescens and R. schneideri, in the Cerrado of central Brazil. In adult individuals of both species, males have more robust forelimbs than females, but females attain larger asymptotic body sizes. In Rhinella rubescens, females have wider heads, whereas in R. schneideri, females bear larger parotoid glands and higher heads than males. Females of R. rubescens grow faster and reach sexual maturity earlier than males (R: 105 days, =: 170 days); in contrast, males of R. schneideri grow faster and attain sexual maturity earlier than females (R: 450 days, =: 340 days). The estimated age of the oldest males and females, respectively, were three and 3.5 years for R. rubescens and five and four years for R. schneideri. Males of R. rubescens were frequently captured a few months after reaching sexual maturity, between six months to one year of age, whereas in R. schneideri, males were frequently captured when sexual maturity was reached from one to 1.5 years of age. Our data indicate that sexual dimorphism results from different growth trajectories before and after sexual maturity. Differences between the two species in morphology, growth, and longevity likely reflect their separation into two morphologically and phylogenetically distinct sister clades.
Aim The astonishing diversity of Neotropical fishes results from historical and ecological proces... more Aim The astonishing diversity of Neotropical fishes results from historical and ecological processes intrinsically related to the geomorphological evolution of this region. Headwater captures are important biogeographical processes that promote dispersal or isolation of fish populations between watersheds. We investigate the effects of headwater captures on the phylogenetic structure of stream fish assemblages among watersheds in the Brazilian Shield highlands. Location Headwaters of Tocantins, Paran a and S~ ao Francisco watersheds, Brazilian Shield, Neotropical region. Methods Based on the phylogenetic relationships of 70 native fish species, we quantified the phylogenetic diversity of each basin, as well as species richness and the phylogenetic beta diversity between basins. Results The Upper Paran a basin showed higher richness and phylogenetic diversity, indicating phylogenetically distant species composition. The number of shared species and phylogenetic beta diversity values were not different from the null expectation, indicating recent exchange of species between the basins. Main conclusions Our results suggest that the fish assemblage of the Upper Paran a basin is older and many species colonized recently the neighbouring Upper Tocantins and S~ ao Francisco basins, highlighting the impact of headwa-ter captures on the community assembly of Neotropical fishes.
Description and phylogenetic relationships of a new genus and two new species of lizards from Bra... more Description and phylogenetic relationships of a new genus and two new species of lizards from Brazilian Amazonia, with nomenclatural comments on the taxonomy of Gymnophthalmidae (Reptilia: Squamata) Abstract We describe a new genus and two new species of gymnophthalmid lizards based on specimens collected from Brazilian Amazonia, mostly in the "arc of deforestation". The new genus is easily distinguished from other Gymnophthalmidae by having very wide, smooth, and imbricate nuchals, arranged in two longitudinal and 6–10 transverse rows from nape to brachium level, followed by much narrower, strongly keeled, lanceolate, and mucronate scales. It also differs from all other Gymnophthalmidae, except Iphisa, by the presence of two longitudinal rows of ventrals. The new genus differs from Iphisa by having two pairs of enlarged chinshields (one in Iphisa); posterior dorsal scales lanceolate, strongly keeled and not arranged in longitudinal rows (dorsals broad, smooth and forming two longitudinal rows), and lateral scales keeled (smooth). Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses based on morphological and molecular data indicate the new species form a clade that is most closely related to Iphisa. We also address several no-menclatural issues and present a revised classification of Gymnophthalmidae.
Levels of biodiversity in the Neotropics are largely underestimated despite centuries of research... more Levels of biodiversity in the Neotropics are largely underestimated despite centuries of research interest in this region. This is particularly true for the Cerrado, the largest Neotropical savanna and a formally recognized biodiversity hotspot. Molecular species delimitation methods have become essential tools to uncover cryptic species and can be notably robust when coupled with morphological information. We present the first evaluation of the monophyly and cryptic speciation of a widespread Cerrado endemic lizard, Gymnodactylus amarali, using phylogenetic and species-trees methods, as well as a coalescentbased Bayesian species delimitation method. We tested whether lineages resulting from the analyses of molecular data are morphologically diagnosed by traditional meristic scale characters. We recovered eight deeply divergent molecular clades within G. amarali, and two additional ones from seasonally dry tropical forest enclaves between the Cerrado and the Caatinga biomes. Analysis of morphological data statistically corroborated the molecular delimitation for all groups, in a pioneering example of the use of support vector machines to investigate morphological differences in animals. The eight G. amarali clades appear monophyletic and endemic to the Cerrado. They display several different properties used by biologists to delineate species and are therefore considered here as candidates for formal taxonomic description. We also present a preliminary account of the biogeographic history of these lineages in the Cerrado, evidence for speciation of sister lineages in the Cerrado-Caatinga contact, and highlight the need for further morphological and genetic studies to assess cryptic diversity in this biodiversity hotspot.
Bulletin of the Museum of Comparative Zoology, 2011
The Anolis chrysolepis species group is distributed across the entire Amazon basin and currently ... more The Anolis chrysolepis species group is distributed across the entire Amazon basin and currently consists of A. bombiceps and five subspecies of A. chrysolepis. These lizards are characterized by moderate size, relatively narrow digital pads, and a small dewlap that does not reach the axilla. We used the mitochondrial gene ND2 to estimate phylogenetic relationships among putative subspecies of A. chrysolepis and taxa previously hypothesized to be their close relatives. We also assessed the congruence between molecular and morphological datasets to evaluate the taxonomic status of group members. On the basis of the two datasets, we present a new taxonomy, elevating each putative subspecies of A. chrysolepis to species status. We provide new morphological diagnoses and new distributional data for each species.
The rapid expansion of human altered landscapes affects biodiversity on every continent. A fundam... more The rapid expansion of human altered landscapes affects biodiversity on every continent. A fundamental goal of conservation biologists is to understand why certain species are at risk of extinction while others are able to persist in human altered landscapes. Afforestation, the conversion of unforested lands to planted forest, is rapidly altering many natural landscapes worldwide. In the Cerrado (Brazilian savanna), a global biodiversity hotspot, a shortage of government incentives has the landscape riddled with abandoned plantation forests that are not subject to active restoration projects. Studies investigating the impacts of abandoned plantations on biodiversity are strikingly limited. We examine the effects of abandoned Eucalyptus plantations on the structure of Cerrado lizard communities. We assessed changes in lizard capture, richness and equitability along cerrado sensu stricto-Eucalyptus transects. Our results indicate abandoned Eucalyptus plantations have subsets of Cerrado species persisting with a great loss of endemic species. The cerrado sensu stricto-Eucalyptus linear transect analysis demonstrated distance from native habitat is positively correlated with loss of biodiversity. We performed correspondence analyses to summarize the variation in species captures across different sites, habitats and pitfall array positions. These analyses depicted strong species associations between habitats and their pitfall array positions. This study is the first to show the negative impacts of abandoned Eucalyptus plantations on Cerrado lizard communities, serving as a cautionary tale of Cerrado biodiversity non-resilience in abandoned Eucalyptus plantations. Mitigation requires that abandoned Eucalyptus plantations are made more suitable to Cerrado lizards by implementing targeted habitat heterogeneity restoration.
We present the first records of Tropidurus callathelys and T. chromatops in Brazil, at Parque Est... more We present the first records of Tropidurus callathelys and T. chromatops in Brazil, at Parque Estadual Serra Ricardo Franco, Mato Grosso. The two species are largely syntopic and associated with rock outcrops on the plateaus of the Serranía de Huanchaca, Bolivia and Brazil. Tropidurus callathelys is more abundant, more heliophilous and uses vertical surfaces more often than T. chromatops. In Brazil, they are apparently restricted to Serra de Ricardo Franco, a protected area threatened by cattle raising, logging and agriculture, still in need of demarcation and a management plan
The lizard genus Kentropyx (Squamata: Teiidae) comprises nine species, which have been placed in ... more The lizard genus Kentropyx (Squamata: Teiidae) comprises nine species, which have been placed in three species groups (calcarata group, associated to forests ecosystems; paulensis and striata groups, associated to open ecosystems). We reconstructed phylogenetic relationships of Kentropyx based on morphology (pholidosis and coloration) and mitochondrial DNA data (12S and 16S), using maximum parsimony and Bayesian methods, and evaluated biogeographic scenarios based on ancestral areas analyses and molecular dating by Bayesian methods. Additionally, we tested the life-history hypothesis that species of Kentropyx inhabiting open ecosystems (under seasonal environments) produce larger clutches with smaller eggs and that species inhabiting forest ecosystems (under aseasonal conditions) produce clutches with fewer and larger eggs, using Stearns’ phylogenetic-subtraction method and canonical phylogenetic ordination to take in to account the effects of phylogeny. Our results showed that Kentropyx comprises three monophyletic groups, with K. striata occupying a basal position in opposition to previous suggestions of relationships. Additionally, Bayesian analysis of divergence time showed that Kentropyx may have originated at the Tertiary (Eocene/Oligocene) and the ‘Pleistocene Refuge Hypothesis’ may not explain the species diversification. Based on ancestral reconstruction and molecular dating, we argued that a savanna ancestor is more likely and that historical events during the Tertiary of South America promoted the differentiation of the genus, coupled with recent Quaternary events that were important as dispersion routes and for the diversification at populational levels. Clutch size and egg volume were not significantly different between major clades and ecosystems of occurrence, even accounting for the phylogenetic effects. Finally, we argue that phylogenetic constraints and phylogenetic inertia might be playing essential roles in life history evolution of Kentropyx.
We investigate the evolution of sperm ultrastructure of three species of Boidae (Epicrates cenchr... more We investigate the evolution of sperm ultrastructure of three species of Boidae (Epicrates cenchria, Boa constrictor amarali, and Corallus hortulanus). Spermatozoa of these species are Wliform consisting of a head region, containing the nucleus and acrosome complex, a midpiece, and a tail region subdivided into principal piece and endpiece. Multilaminar membranes and extracellular microtubules were observed next to the plasma membrane of the spermatozoa. The following diVerences were observed among the species: ridge on acrosome surface in Boa constrictor amarali (absent in Epicrates cenchria and Corallus hortulanus), stopperlike perforatorium base plate in Boa constrictor amarali and Epicrates cenchria (absent in Corallus hortulanus), rounded mitochondria in transverse section in Epicrates cenchria and Corallus hortulanus (irregular in Boa constrictor amarali). We mapped sperm characters onto two phylogenies based on morphological (Kluge in Misc Publ Mus Zool Univ Michigan 178:1-58, 1991) and molecular (Austin in Copeia 2:341-352, 2000) data, using a number of squamate species as outgroups. We identiWed 31 unambiguous character transformations in the morphological phylogeny and 30 in the molecular phylogeny, but only 13 and 12 transformations, respectively, are possible synapomorphies. We identiWed novel sperm synapomorphies, which were common between the morphological and molecular phylogenies: absence of perforatorium base plate and mitochondria arranged as sinuous tubes in oblique section (Serpentes), acrosome vesicle not subdivided and Wbers 3 and 8 at the anteriormost region of principal piece (Boidae), and absence of an electron dense structure inside the proximal centriole (Elapidae + Colubridae). Our results suggest greater agreement between sperm ultrastructure and gross anatomical characters. In addition, we found no tendency for more homoplasies in the sperm head than in the Xagellum, as recorded in previous studies.
We make detailed comparisons of the ultrastructure of the spermatozoon among three species of the... more We make detailed comparisons of the ultrastructure of the spermatozoon among three species of the family Hylidae, Hyla pseudopseudis, Scinax rostratus, and S. squalirostris. The acrosome complex consists of two conical structures covering the nuclear rostrum, the acrosome vesicle, and the subacrosomal cone. The nucleus has a moderately condensed chromatin with a conical shape in longitudinal sections and a circular shape in cross-sections. In H. pseudopseudis, mitochondria are numerous and circular, and in S. rostratus and S. squalirostris there are fewer mitochondria that are more elongate in longitudinal and transverse sections. In H. pseudopseudis, the mitochondrial collar starts adjacent to the distal centriole, occupying the whole midpiece, whereas in both Scinax species the mitochondrial collar starts only at the posterior one-third of the midpiece. In both Scinax species, the presence of juxta-axonemal fiber, axial sheath, and axial fiber in the tail are seemingly plesiomorphic characters, widespread among bufonoid frogs. In H. pseudopseudis, however, the absence of axial fiber and axial sheath seems to be derived from the typical bufonoid condition. The differences between Hyla and Scinax sperm endorse the separation of the two genera and suggest that sperm ultrastructure can be a useful tool to investigate relationships at the intrafamily level.
Aim: Small geographic ranges make species especially prone to extinction from anthropogenic
distu... more Aim: Small geographic ranges make species especially prone to extinction from anthropogenic disturbances or natural stochastic events. We assemble and analyse a comprehensive dataset of all the world’s lizard species and identify the species with the smallest ranges—those known only from their type localities. We compare them to wide-ranging species to infer whether specific geographic regions or biological traits predispose species to have small ranges. Location: Global. Methods: We extensively surveyed museum collections, the primary literature and our own field records to identify all the species of lizards with a maximum linear geographic extent of <10 km. We compared their biogeography, key biological traits and threat status to those of all other lizards. Results: One in seven lizards (927 of the 6,568 currently recognized species) are known only from their type localities. These include 213 species known only from a single specimen. Compared to more wide-ranging taxa, they mostly inhabit relatively inaccessible regions at lower, mostly tropical, latitudes. Surprisingly, we found that burrowing lifestyle is a relatively unimportant driver of small range size. Geckos are especially prone to having tiny ranges, and skinks dominate lists of such species not seen for over 50 years, as well as of species known only from their holotype. Two-thirds of these species have no IUCN assessments, and at least 20 are extinct. Main conclusions: Fourteen per cent of lizard diversity is restricted to a single location, often in inaccessible regions. These species are elusive, usually poorly known and little studied. Many face severe extinction risk, but current knowledge is inadequate to properly assess this for all of them. We recommend that such species become the focus of taxonomic, ecological and survey efforts.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting... more BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Aim In the New World coral-snake complex, Micrurus species presumably serve as Batesian models fo... more Aim In the New World coral-snake complex, Micrurus species presumably serve as Batesian models for some species of Colubridae, including Oxyrhopus. To better understand the evolutionary role of mimicry, we explored the distributional overlap of Micrurus (models) and Oxyrhopus (mimics), the association between species and pattern richness of both taxa, and the relationship between mimetic fidelity and model diversity. Location The Neotropical region and southern-most Nearctic region. Methods We classified colour patterns and delineated the geographical distributions of species in a 1° grid, spanning the distributions of both genera. We used generalized linear models to test for significant associations of species and colour patterns. We used guided regularized random forests to identify, among Micrurus colour patterns, the best predictors of the presence and richness of Oxyrhopus colour patterns. To account for spatial autocorrelation, we implemented Bayesian hierarchical models using the integral nested Laplace approximation with a conditional autoregressive prior. Results With few exceptions, the presence and richness of species of Micrurus bearing a given colour pattern in grid cells were good predictors of the presence and richness of Oxyrhopus species bearing the same colour pattern. However, these relationships did not hold when we accounted for species of Micrurus bearing different colour patterns, except in a few cases. The presence of perfect (i.e. those that have a matching Micrurus model) and imperfect (those that do not) Oxyrhopus colour patterns in grid cells was positively correlated with the richness of Micrurus colour patterns. Main conclusions Mimicry complexes may not rely upon perfect signal matching and distributional overlap as previously supposed. Tests of mimetic relationships based on geographical distributions must account for alternative hypotheses including organisms that do not appear to be close mimics. Mimicry complexes may capitalize upon model signal diversity, allowing for the diversification of lin-eages with warning coloration in the face of stabilizing selection.
—A central issue in comparative biology is identifying the relative importance of historical (phy... more —A central issue in comparative biology is identifying the relative importance of historical (phylogenetic) versus present-day (ecological) factors in shaping phenotypic traits of organisms. Herein, we investigate effects of sex, ontogeny, and season on diet of Epipedobates flavopictus, a species restricted to open landscapes in central Brazil. Based on prey frequency, number, and volume, the most important prey categories were ants, termites, beetles, spiders, and orthopterans. Prey number and volume increased significantly with snout–vent length (SVL), and the consumption of termites also increased with SVL. There were few effects of sex and season upon diet composition, average prey number, or average prey volume, all independent of SVL. Reproductive females consumed larger prey, in great numbers, likely to increase energy uptake. As is true for most congeners, as well as species of closely related genera, ants are an important component in the diet of E. flavopictus. However, in contrast to its forest relatives, E. flavopictus consumes large amounts of termites, revealing the influence of prevailing ecological conditions. The small volume of ants in the diet of E. flavopictus and the high toxicity of its skin are not in agreement with the hypothesis of a causal relationship between skin toxicity and ant consumption.
This study describes the spermatozoa of the dendrobatids Epipedobates femoralis and Colostethus s... more This study describes the spermatozoa of the dendrobatids Epipedobates femoralis and Colostethus sp. using light and transmission electron microscopy. Both species possess a biflagellate spermatozoon, an unusual characteristic only previously reported in two anuran species belonging to the families Leptodactylidae and Racophoridae. The acrosomal complex of both species consists of a conical acrosomal vesicle and a subacrosomal cone, both of which cover the anterior portion of the nucleus , but to differing extents. In the midpiece, the cen-trioles are disposed parallel to each other and to the cell axis and give rise to two axonemes. Two paraxonemal rods were also seen entering the nuclear fossa. Both flagella are surrounded by a single mitochondrial collar. Each flagellum is formed by an axial fiber connected to the axoneme by an axial sheath; juxta-axonemal fibers are absent. Our data seem to support that Epipedobates femo-ralis should be placed in a separate clade possibly related to Colosthetus and that these two genera may not be monophyletic.
In most amphibians, females are the larger sex presumably due to selection for larger reproductiv... more In most amphibians, females are the larger sex presumably due to selection for larger reproductive output. Sexual selection may, however, produce larger males and also lead to the evolution of secondary sexual characteristics. The proximate causes of sexual dimorphism are related to differences in growth rates and longevity, but these data are scanty for most amphibian species and often depend on long-term demographic studies. Here we use skeletochronology and mark–recapture data obtained on a weekly basis over five years to investigate the sexual dimorphism in body size and shape, growth, and longevity of two toad species, Rhinella rubescens and R. schneideri, in the Cerrado of central Brazil. In adult individuals of both species, males have more robust forelimbs than females, but females attain larger asymptotic body sizes. In Rhinella rubescens, females have wider heads, whereas in R. schneideri, females bear larger parotoid glands and higher heads than males. Females of R. rubescens grow faster and reach sexual maturity earlier than males (R: 105 days, =: 170 days); in contrast, males of R. schneideri grow faster and attain sexual maturity earlier than females (R: 450 days, =: 340 days). The estimated age of the oldest males and females, respectively, were three and 3.5 years for R. rubescens and five and four years for R. schneideri. Males of R. rubescens were frequently captured a few months after reaching sexual maturity, between six months to one year of age, whereas in R. schneideri, males were frequently captured when sexual maturity was reached from one to 1.5 years of age. Our data indicate that sexual dimorphism results from different growth trajectories before and after sexual maturity. Differences between the two species in morphology, growth, and longevity likely reflect their separation into two morphologically and phylogenetically distinct sister clades.
Aim The astonishing diversity of Neotropical fishes results from historical and ecological proces... more Aim The astonishing diversity of Neotropical fishes results from historical and ecological processes intrinsically related to the geomorphological evolution of this region. Headwater captures are important biogeographical processes that promote dispersal or isolation of fish populations between watersheds. We investigate the effects of headwater captures on the phylogenetic structure of stream fish assemblages among watersheds in the Brazilian Shield highlands. Location Headwaters of Tocantins, Paran a and S~ ao Francisco watersheds, Brazilian Shield, Neotropical region. Methods Based on the phylogenetic relationships of 70 native fish species, we quantified the phylogenetic diversity of each basin, as well as species richness and the phylogenetic beta diversity between basins. Results The Upper Paran a basin showed higher richness and phylogenetic diversity, indicating phylogenetically distant species composition. The number of shared species and phylogenetic beta diversity values were not different from the null expectation, indicating recent exchange of species between the basins. Main conclusions Our results suggest that the fish assemblage of the Upper Paran a basin is older and many species colonized recently the neighbouring Upper Tocantins and S~ ao Francisco basins, highlighting the impact of headwa-ter captures on the community assembly of Neotropical fishes.
Description and phylogenetic relationships of a new genus and two new species of lizards from Bra... more Description and phylogenetic relationships of a new genus and two new species of lizards from Brazilian Amazonia, with nomenclatural comments on the taxonomy of Gymnophthalmidae (Reptilia: Squamata) Abstract We describe a new genus and two new species of gymnophthalmid lizards based on specimens collected from Brazilian Amazonia, mostly in the "arc of deforestation". The new genus is easily distinguished from other Gymnophthalmidae by having very wide, smooth, and imbricate nuchals, arranged in two longitudinal and 6–10 transverse rows from nape to brachium level, followed by much narrower, strongly keeled, lanceolate, and mucronate scales. It also differs from all other Gymnophthalmidae, except Iphisa, by the presence of two longitudinal rows of ventrals. The new genus differs from Iphisa by having two pairs of enlarged chinshields (one in Iphisa); posterior dorsal scales lanceolate, strongly keeled and not arranged in longitudinal rows (dorsals broad, smooth and forming two longitudinal rows), and lateral scales keeled (smooth). Maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses based on morphological and molecular data indicate the new species form a clade that is most closely related to Iphisa. We also address several no-menclatural issues and present a revised classification of Gymnophthalmidae.
Levels of biodiversity in the Neotropics are largely underestimated despite centuries of research... more Levels of biodiversity in the Neotropics are largely underestimated despite centuries of research interest in this region. This is particularly true for the Cerrado, the largest Neotropical savanna and a formally recognized biodiversity hotspot. Molecular species delimitation methods have become essential tools to uncover cryptic species and can be notably robust when coupled with morphological information. We present the first evaluation of the monophyly and cryptic speciation of a widespread Cerrado endemic lizard, Gymnodactylus amarali, using phylogenetic and species-trees methods, as well as a coalescentbased Bayesian species delimitation method. We tested whether lineages resulting from the analyses of molecular data are morphologically diagnosed by traditional meristic scale characters. We recovered eight deeply divergent molecular clades within G. amarali, and two additional ones from seasonally dry tropical forest enclaves between the Cerrado and the Caatinga biomes. Analysis of morphological data statistically corroborated the molecular delimitation for all groups, in a pioneering example of the use of support vector machines to investigate morphological differences in animals. The eight G. amarali clades appear monophyletic and endemic to the Cerrado. They display several different properties used by biologists to delineate species and are therefore considered here as candidates for formal taxonomic description. We also present a preliminary account of the biogeographic history of these lineages in the Cerrado, evidence for speciation of sister lineages in the Cerrado-Caatinga contact, and highlight the need for further morphological and genetic studies to assess cryptic diversity in this biodiversity hotspot.
Bulletin of the Museum of Comparative Zoology, 2011
The Anolis chrysolepis species group is distributed across the entire Amazon basin and currently ... more The Anolis chrysolepis species group is distributed across the entire Amazon basin and currently consists of A. bombiceps and five subspecies of A. chrysolepis. These lizards are characterized by moderate size, relatively narrow digital pads, and a small dewlap that does not reach the axilla. We used the mitochondrial gene ND2 to estimate phylogenetic relationships among putative subspecies of A. chrysolepis and taxa previously hypothesized to be their close relatives. We also assessed the congruence between molecular and morphological datasets to evaluate the taxonomic status of group members. On the basis of the two datasets, we present a new taxonomy, elevating each putative subspecies of A. chrysolepis to species status. We provide new morphological diagnoses and new distributional data for each species.
The rapid expansion of human altered landscapes affects biodiversity on every continent. A fundam... more The rapid expansion of human altered landscapes affects biodiversity on every continent. A fundamental goal of conservation biologists is to understand why certain species are at risk of extinction while others are able to persist in human altered landscapes. Afforestation, the conversion of unforested lands to planted forest, is rapidly altering many natural landscapes worldwide. In the Cerrado (Brazilian savanna), a global biodiversity hotspot, a shortage of government incentives has the landscape riddled with abandoned plantation forests that are not subject to active restoration projects. Studies investigating the impacts of abandoned plantations on biodiversity are strikingly limited. We examine the effects of abandoned Eucalyptus plantations on the structure of Cerrado lizard communities. We assessed changes in lizard capture, richness and equitability along cerrado sensu stricto-Eucalyptus transects. Our results indicate abandoned Eucalyptus plantations have subsets of Cerrado species persisting with a great loss of endemic species. The cerrado sensu stricto-Eucalyptus linear transect analysis demonstrated distance from native habitat is positively correlated with loss of biodiversity. We performed correspondence analyses to summarize the variation in species captures across different sites, habitats and pitfall array positions. These analyses depicted strong species associations between habitats and their pitfall array positions. This study is the first to show the negative impacts of abandoned Eucalyptus plantations on Cerrado lizard communities, serving as a cautionary tale of Cerrado biodiversity non-resilience in abandoned Eucalyptus plantations. Mitigation requires that abandoned Eucalyptus plantations are made more suitable to Cerrado lizards by implementing targeted habitat heterogeneity restoration.
We present the first records of Tropidurus callathelys and T. chromatops in Brazil, at Parque Est... more We present the first records of Tropidurus callathelys and T. chromatops in Brazil, at Parque Estadual Serra Ricardo Franco, Mato Grosso. The two species are largely syntopic and associated with rock outcrops on the plateaus of the Serranía de Huanchaca, Bolivia and Brazil. Tropidurus callathelys is more abundant, more heliophilous and uses vertical surfaces more often than T. chromatops. In Brazil, they are apparently restricted to Serra de Ricardo Franco, a protected area threatened by cattle raising, logging and agriculture, still in need of demarcation and a management plan
The lizard genus Kentropyx (Squamata: Teiidae) comprises nine species, which have been placed in ... more The lizard genus Kentropyx (Squamata: Teiidae) comprises nine species, which have been placed in three species groups (calcarata group, associated to forests ecosystems; paulensis and striata groups, associated to open ecosystems). We reconstructed phylogenetic relationships of Kentropyx based on morphology (pholidosis and coloration) and mitochondrial DNA data (12S and 16S), using maximum parsimony and Bayesian methods, and evaluated biogeographic scenarios based on ancestral areas analyses and molecular dating by Bayesian methods. Additionally, we tested the life-history hypothesis that species of Kentropyx inhabiting open ecosystems (under seasonal environments) produce larger clutches with smaller eggs and that species inhabiting forest ecosystems (under aseasonal conditions) produce clutches with fewer and larger eggs, using Stearns’ phylogenetic-subtraction method and canonical phylogenetic ordination to take in to account the effects of phylogeny. Our results showed that Kentropyx comprises three monophyletic groups, with K. striata occupying a basal position in opposition to previous suggestions of relationships. Additionally, Bayesian analysis of divergence time showed that Kentropyx may have originated at the Tertiary (Eocene/Oligocene) and the ‘Pleistocene Refuge Hypothesis’ may not explain the species diversification. Based on ancestral reconstruction and molecular dating, we argued that a savanna ancestor is more likely and that historical events during the Tertiary of South America promoted the differentiation of the genus, coupled with recent Quaternary events that were important as dispersion routes and for the diversification at populational levels. Clutch size and egg volume were not significantly different between major clades and ecosystems of occurrence, even accounting for the phylogenetic effects. Finally, we argue that phylogenetic constraints and phylogenetic inertia might be playing essential roles in life history evolution of Kentropyx.
We investigate the evolution of sperm ultrastructure of three species of Boidae (Epicrates cenchr... more We investigate the evolution of sperm ultrastructure of three species of Boidae (Epicrates cenchria, Boa constrictor amarali, and Corallus hortulanus). Spermatozoa of these species are Wliform consisting of a head region, containing the nucleus and acrosome complex, a midpiece, and a tail region subdivided into principal piece and endpiece. Multilaminar membranes and extracellular microtubules were observed next to the plasma membrane of the spermatozoa. The following diVerences were observed among the species: ridge on acrosome surface in Boa constrictor amarali (absent in Epicrates cenchria and Corallus hortulanus), stopperlike perforatorium base plate in Boa constrictor amarali and Epicrates cenchria (absent in Corallus hortulanus), rounded mitochondria in transverse section in Epicrates cenchria and Corallus hortulanus (irregular in Boa constrictor amarali). We mapped sperm characters onto two phylogenies based on morphological (Kluge in Misc Publ Mus Zool Univ Michigan 178:1-58, 1991) and molecular (Austin in Copeia 2:341-352, 2000) data, using a number of squamate species as outgroups. We identiWed 31 unambiguous character transformations in the morphological phylogeny and 30 in the molecular phylogeny, but only 13 and 12 transformations, respectively, are possible synapomorphies. We identiWed novel sperm synapomorphies, which were common between the morphological and molecular phylogenies: absence of perforatorium base plate and mitochondria arranged as sinuous tubes in oblique section (Serpentes), acrosome vesicle not subdivided and Wbers 3 and 8 at the anteriormost region of principal piece (Boidae), and absence of an electron dense structure inside the proximal centriole (Elapidae + Colubridae). Our results suggest greater agreement between sperm ultrastructure and gross anatomical characters. In addition, we found no tendency for more homoplasies in the sperm head than in the Xagellum, as recorded in previous studies.
We make detailed comparisons of the ultrastructure of the spermatozoon among three species of the... more We make detailed comparisons of the ultrastructure of the spermatozoon among three species of the family Hylidae, Hyla pseudopseudis, Scinax rostratus, and S. squalirostris. The acrosome complex consists of two conical structures covering the nuclear rostrum, the acrosome vesicle, and the subacrosomal cone. The nucleus has a moderately condensed chromatin with a conical shape in longitudinal sections and a circular shape in cross-sections. In H. pseudopseudis, mitochondria are numerous and circular, and in S. rostratus and S. squalirostris there are fewer mitochondria that are more elongate in longitudinal and transverse sections. In H. pseudopseudis, the mitochondrial collar starts adjacent to the distal centriole, occupying the whole midpiece, whereas in both Scinax species the mitochondrial collar starts only at the posterior one-third of the midpiece. In both Scinax species, the presence of juxta-axonemal fiber, axial sheath, and axial fiber in the tail are seemingly plesiomorphic characters, widespread among bufonoid frogs. In H. pseudopseudis, however, the absence of axial fiber and axial sheath seems to be derived from the typical bufonoid condition. The differences between Hyla and Scinax sperm endorse the separation of the two genera and suggest that sperm ultrastructure can be a useful tool to investigate relationships at the intrafamily level.
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Papers by Guarino Colli
disturbances or natural stochastic events. We assemble and analyse a
comprehensive dataset of all the world’s lizard species and identify the species with
the smallest ranges—those known only from their type localities. We compare them to
wide-ranging
species to infer whether specific geographic regions or biological traits
predispose species to have small ranges.
Location: Global.
Methods: We extensively surveyed museum collections, the primary literature and
our own field records to identify all the species of lizards with a maximum linear geographic
extent of <10 km. We compared their biogeography, key biological traits and
threat status to those of all other lizards.
Results: One in seven lizards (927 of the 6,568 currently recognized species) are
known only from their type localities. These include 213 species known only from a
single specimen. Compared to more wide-ranging
taxa, they mostly inhabit relatively
inaccessible regions at lower, mostly tropical, latitudes. Surprisingly, we found that
burrowing lifestyle is a relatively unimportant driver of small range size. Geckos are
especially prone to having tiny ranges, and skinks dominate lists of such species not
seen for over 50 years, as well as of species known only from their holotype. Two-thirds
of these species have no IUCN assessments, and at least 20 are extinct.
Main conclusions: Fourteen per cent of lizard diversity is restricted to a single location,
often in inaccessible regions. These species are elusive, usually poorly known and little
studied. Many face severe extinction risk, but current knowledge is inadequate to
properly assess this for all of them. We recommend that such species become the
focus of taxonomic, ecological and survey efforts.
disturbances or natural stochastic events. We assemble and analyse a
comprehensive dataset of all the world’s lizard species and identify the species with
the smallest ranges—those known only from their type localities. We compare them to
wide-ranging
species to infer whether specific geographic regions or biological traits
predispose species to have small ranges.
Location: Global.
Methods: We extensively surveyed museum collections, the primary literature and
our own field records to identify all the species of lizards with a maximum linear geographic
extent of <10 km. We compared their biogeography, key biological traits and
threat status to those of all other lizards.
Results: One in seven lizards (927 of the 6,568 currently recognized species) are
known only from their type localities. These include 213 species known only from a
single specimen. Compared to more wide-ranging
taxa, they mostly inhabit relatively
inaccessible regions at lower, mostly tropical, latitudes. Surprisingly, we found that
burrowing lifestyle is a relatively unimportant driver of small range size. Geckos are
especially prone to having tiny ranges, and skinks dominate lists of such species not
seen for over 50 years, as well as of species known only from their holotype. Two-thirds
of these species have no IUCN assessments, and at least 20 are extinct.
Main conclusions: Fourteen per cent of lizard diversity is restricted to a single location,
often in inaccessible regions. These species are elusive, usually poorly known and little
studied. Many face severe extinction risk, but current knowledge is inadequate to
properly assess this for all of them. We recommend that such species become the
focus of taxonomic, ecological and survey efforts.