377 research outputs found
A new species of marsupial frog (Hylidae: Gastrotheca) from Venezuela
http://deepblue.lib.umich.edu/bitstream/2027.42/57126/1/OP690.pd
The frogs of the hylid genus Phrynohyas Fitzinger, 1843
http://deepblue.lib.umich.edu/bitstream/2027.42/56340/1/MP096.pd
A systematic study of the lizards of the deppei group (Genus Cnemidophorus) in Mexico and Guatemala
http://deepblue.lib.umich.edu/bitstream/2027.42/56355/1/MP111.pd
Divergence of thermal physiological traits in terrestrial breeding frogs along a tropical elevational gradient
Critical thermal limits are thought to be correlated with the elevational distribution of species living in tropical montane regions, but with upper limits being relatively invariant compared to lower limits. To test this hypothesis, we examined the variation of thermal physiological traits in a group of terrestrial breeding frogs (Craugastoridae) distributed along a tropical elevational gradient. We measured the critical thermal maximum (CTmax; n = 22 species) and critical thermal minimum (CTmin; n = 14 species) of frogs captured between the Amazon floodplain (250 m asl) and the high Andes (3,800 m asl). After inferring a multilocus species tree, we conducted a phylogenetically informed test of whether body size, body mass, and elevation contributed to the observed variation in CTmax and CTmin along the gradient. We also tested whether CTmax and CTmin exhibit different rates of change given that critical thermal limits (and their plasticity) may have evolved differently in response to different temperature constraints along the gradient. Variation of critical thermal traits was significantly correlated with speciesâ elevational midpoint, their maximum and minimum elevations, as well as the maximum air temperature and the maximum operative temperature as measured across this gradient. Both thermal limits showed substantial variation, but CTmin exhibited relatively faster rates of change than CTmax, as observed in other taxa. Nonetheless, our findings call for caution in assuming inflexibility of upper thermal limits and underscore the value of collecting additional empirical data on speciesâ thermal physiology across elevational gradients.A widely held assumption is that climatic niches have not changed along the history of species, both within and among closely related species. Using a phylogenetic framework, this study documents high variability in both elevational distribution and tolerance to heat among closely related species. Our findings suggest that thermal traits in ectotherms can adjust rapidly and so cannot be simply extrapolated from relatives.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136724/1/ece32929_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136724/2/ece32929.pd
Postmetamorphic ontogenetic allometry and the evolution of skull shape in Nest-building frogs Leptodactylus (Anura: Leptodactylidae)
Allometry constitutes an important source of morphological variation. However, its influence in head development in anurans has been poorly explored. By using geometric morphometrics followed by statistical and comparative methods we analyzed patterns of allometric change during cranial postmetamorphic ontogeny in species of Nest-building frogs Leptodactylus (Leptodactylidae). We found that the anuran skull is not a static structure, and allometry plays an important role in defining its shape in this group. Similar to other groups with biphasic life-cycle, and following a general trend in vertebrates, ontogenetic changes mostly involve rearrangement in rostral, otoccipital, and suspensorium regions. Ontogenetic transformations are paralleled by shape changes associated with evolutionary change in size, such that the skulls of species of different intrageneric groups are scaled to each other, and small and large species show patterns of paedomorphic/peramorphic features, respectively. Allometric trajectories producing those phenotypes are highly evolvable though, with shape change direction and magnitude varying widely among clades, and irrespective of changes in absolute body size. These results reinforce the importance of large-scale comparisons of growth patterns to understand the plasticity, evolution, and polarity of morphological changes in different clades.Fil: Duport Bru, Ana Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Ponssa, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Vera Candioti, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentin
Testing main Amazonian rivers as barriers across time and space within widespread taxa
AimPresent Amazonian diversity patterns can result from many different mechanisms and, consequently, the factors contributing to divergence across regions and/or taxa may differ. Nevertheless, the riverâ barrier hypothesis is still widely invoked as a causal process in divergence of Amazonian species. Here we use modelâ based phylogeographic analyses to test the extent to which major Amazonian rivers act similarly as barriers across time and space in two broadly distributed Amazonian taxa.LocalAmazon rain forest.TaxonThe lizard Gonatodes humeralis (Sphaerodactylidae) and the tree frog Dendropsophus leucophyllatus (Hylidae).MethodsWe obtained RADseq data for samples distributed across main river barriers, representing main Areas of Endemism previously proposed for the region. We conduct modelâ based phylogeographic and genetic differentiation analyses across each population pair.ResultsMeasures of genetic differentiation (based on FST calculated from genomic data) show that all rivers are associated with significant genetic differentiation. Parameters estimated under investigated divergence models showed that divergence times for populations separated by each of the 11 bordering rivers were all fairly recent. The degree of differentiation consistently varied between taxa and among rivers, which is not an artifact of any corresponding difference in the genetic diversities of the respective taxa, or to amounts of migration based on analyses of the siteâ frequency spectrum.Main conclusionsTaken together, our results support a dispersal (rather than vicariance) history, without strong evidence of congruence between these species and rivers. However, once a species crossed a river, populations separated by each and every river have remained isolatedâ in this sense, rivers act similarly as barriers to any further gene flow. This result suggests differing degrees of persistence and gives rise to the seeming contradiction that the divergence process indeed varies across time, space and species, even though major Amazonian rivers have acted as secondary barriers to gene flow in the focal taxa.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152608/1/jbi13676_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152608/2/jbi13676.pd
Global patterns of body size evolution are driven by precipitation in legless amphibians
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordBody size shapes ecological interactions across and within species, ultimately influencing the evolution of large-scale biodiversity patterns. Therefore, macroecological studies of body size provide a link between spatial variation in selection regimes and the evolution of animal assemblages through space. Multiple hypotheses have been formulated to explain the evolution of spatial gradients of animal body size, predominantly driven by thermal (Bergmann's rule), humidity (‘water conservation hypothesis’) and resource constraints (‘resource rule’, ‘seasonality rule’) on physiological homeostasis. However, while integrative tests of all four hypotheses combined are needed, the focus of such empirical efforts needs to move beyond the traditional endotherm–ectotherm dichotomy, to instead interrogate the role that variation in lifestyles within major lineages (e.g. classes) play in creating neglected scenarios of selection via analyses of largely overlooked environment–body size interactions. Here, we test all four rules above using a global database spanning 99% of modern species of an entire Order of legless, predominantly underground-dwelling amphibians (Gymnophiona, or caecilians). We found a consistent effect of increasing precipitation (and resource abundance) on body size reductions (supporting the water conservation hypothesis), while Bergmann's, the seasonality and resource rules are rejected. We argue that subterranean lifestyles minimize the effects of aboveground selection agents, making humidity a dominant selection pressure – aridity promotes larger body sizes that reduce risk of evaporative dehydration, while smaller sizes occur in wetter environments where dehydration constraints are relaxed. We discuss the links between these principles with the physiological constraints that may have influenced the tropically-restricted global radiation of caecilians.Natural Environment Research Council (NERC)O2National Lottery - Big Lottery Fun
The First Bromeligenous Species of Dendropsophus (Anura: Hylidae) from Brazil\u27s Atlantic Forest
We describe a new treefrog species of Dendropsophus collected on rocky outcrops in the Brazilian Atlantic Forest. Ecologically, the new species can be distinguished from all known congeners by having a larval phase associated with rainwater accumulated in bromeliad phytotelms instead of temporary or lentic water bodies. Phylogenetic analysis based on molecular data confirms that the new species is a member of Dendropsophus; our analysis does not assign it to any recognized species group in the genus. Morphologically, based on comparison with the 96 known congeners, the new species is diagnosed by its small size, framed dorsal color pattern, and short webbing between toes IV-V. The advertisement call is composed of a moderate-pitched two-note call (~5 kHz). The territorial call contains more notes and pulses than the advertisement call. Field observations suggest that this new bromeligenous species uses a variety of bromeliad species to breed in, and may be both territorial and exhibit male parental care
Vocalizations and comments on the relationships of Hypsiboas ericae (Amphibia, Hylidae)
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