Forests as promoters of terrestrial life-history strategies in East African amphibians (original) (raw)
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A hotspot revisited - a biogeographical analysis of West African amphibians
Diversity and Distributions, 2011
The study was aimed at testing whether West Africa can be regarded as a distinct biogeographic region based on amphibian assemblages. If so, we asked what were the relationships of these assemblages with those in Central Africa, and whether West African amphibian distributions showed biogeographic substructure. We further investigated what events or processes may explain the observed patterns.
2012
Making generalizations about the impact of commercial selective logging on biodiversity has so far remained elusive. Species responses to logging depend on a number of factors, many of which have not been studied in detail. These factors may include the natural forest conditions (forest types) under which logging impacts are investigated; but this question has so far remained unexamined. In a largescale replicate study we aimed at clarifying the relationship between logging and forest types on leaf litter frogs. We contrast three distinct and naturally occurring forest types, including wet evergreen, moist evergreen and semi-deciduous forests. Selectively logged sites were compared with primary forest sites for each forest type. We found that the response of frog communities to logging varies in different forest types. In the wet evergreen forest, richness was higher in logged forest than primary forest, while diversity measures were not different between logged and primary forest habitats. In the moist evergreen, richness and diversity were higher in selectively logged areas compared with primary forest habitats. In the semi-deciduous, logged forests were characterized by drastic loss of forest specialists, reduced richness, and diversity. These results indicate that the net effect of logging varies with respect to forest type. Forest types that are characterized by adverse climatic conditions (i.e., low rainfall and protracted dry seasons) are more likely to produce negative effects on leaf litter anuran communities. For comparisons of the impact of logging on species to be effective, future research must endeavor to include details of forest type.
Terrestrial reproduction as an adaptation to steep terrain in African toads
Proceedings. Biological sciences, 2017
How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial...
Desert amphibian selection of arid land breeding habitat undermines reproductive effort
Oecologia, 2017
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Integrating life-history traits and amphibian upland habitat use in a Neotropical hotspot.pdf
Atlantic forest Brazil Frog Wetland Reproductive strategy Sex ratio a b s t r a c t Effective management of semi-aquatic animals requires detailed information on upland habitat use around aquatic habitats. Quantifying the amount of habitats needed to sustain local animals' populations is a crucial criterion when setting protective buffers to water bodies, especially for amphibians, which depend on these upland habitats for breeding and development. Differences in upland habitat use can emerge among amphibian species with distinct life-history traits, including reproductive-strategy (pondbreeding vs. non-pond breeding anurans), life-stage (adults vs. juveniles), and sex (males vs. females). To date there has been no quantitative study of upland habitat use in the Neotropics, which can provide a baseline for quantifying the amount of upland forested habitats needed to sustain local amphibian populations. We monitored three ponds for over two sampling year using drift fences with pitfall traps to investigate how reproductive-strategy, life-stage, and sex affect anuran upland habitat use in a forest remnant in the Atlantic Forest hotspot. We found no differences in upland habitat use between adult and juvenile anurans. However, we found that although the species richness of pond-breeding and non-pond breeding anurans was similar near wetlands, there was greater abundance of pond-breeding compared to non-pond breeding anurans. We also found a strong difference between the sexes in pond-breeding anurans, with males remaining closer to wetlands than females. Thus, the sex ratio of amphibian populations can be strongly skewed toward males if only small protective terrestrial buffers (50-m) are enforced during land development. Our findings also point to the inadequacy of current Brazilian policies to protect small wetlands and the fauna that depend on them. We recommend that policymakers adjust regulatory criteria to set hierarchical protective buffers around wetlands allowing different levels of landuse intervention.
Journal of Biogeography, 2012
Aim The diversity of reproductive modes among amphibians constitutes a striking example of how differences in the biology of species provide important explanations for species distribution patterns on a broad scale. We hypothesize that sites with a higher humidity level will support more modes of reproduction than drier sites and will consequently exhibit a higher phylogenetic diversity. Furthermore, if there is a gradient in the tolerance of reproductive modes to desiccation, there will be a nested pattern in the composition of reproductive modes among sites.Location Twenty-seven forest sites in the Brazilian Atlantic Forest.Methods Through a path analysis approach, we evaluated the direct and indirect effects of the humidity level on the number of reproductive modes, as well as the relative importance of both variables on amphibian phylogenetic diversity. A nestedness analysis was used to quantify the extent to which the compositions of both species and reproductive modes in drier sites correspond to subsets of those in sites with higher annual precipitation.Results We found that the reproductive modes present in drier sites are non-random subsets of those present in sites with higher humidity levels. Because reproductive modes are phylogenetically conserved among amphibians, sites with a greater number of reproductive modes supported greater phylogenetic diversity. Sites with high precipitation throughout the year provided suitable environmental conditions for a larger number of reproductive modes, whereas sites with low precipitation and typical seasonal climates supported only those reproductive modes specialized to resist desiccation.Main conclusions Our results show that humidity-related variables are key environmental factors related to both the richness of reproductive modes and phylogenetic diversity. Our results support the hypothesis that the higher phylogenetic diversity found in moister sites reflects differences in the tolerance to desiccation among different reproductive modes. Given that reproductive modes are associated with susceptibility to desiccation, their incorporation into explanatory models may trigger a significant advance in the understanding of the mechanisms regulating the species richness and composition of amphibian communities.
PLoS ONE, 2012
Terrestrialization, the evolution of non-aquatic oviposition, and miniaturization, the evolution of tiny adult body size, are recurring trends in amphibian evolution, but the relationships among the traits that characterize these phenomena are not well understood. Furthermore, these traits have been identified as possible ''key innovations'' that are predicted to increase rates of speciation in those lineages in which they evolve. We examine terrestrialization and miniaturization in sub-Saharan puddle frogs (Phrynobatrachidae) in a phylogenetic context to investigate the relationship between adaptation and diversification through time. We use relative dating techniques to ascertain if character trait shifts are associated with increased diversification rates, and we evaluate the likelihood that a single temporal event can explain the evolution of those traits. Results indicate alternate reproductive modes evolved independently in Phrynobatrachus at least seven times, including terrestrial deposition of eggs and terrestrial, non-feeding larvae. These shifts towards alternate reproductive modes are not linked to a common temporal event. Contrary to the ''key innovations'' hypothesis, clades that exhibit alternate reproductive modes have lower diversification rates than those that deposit eggs aquatically. Adult habitat, pedal webbing and body size have no effect on diversification rates. Though these traits putatively identified as key innovations for Phrynobatrachus do not seem to be associated with increased speciation rates, they may still provide opportunities to extend into new niches, thus increasing overall diversity.
Geographic variation in life-history characteristics of amphibians: a review
Journal of Animal Ecology, 2003
1. This review examines the intraspecific patterns and differences in life-history traits of amphibian populations living at different altitudes and latitudes. Specifically we examined differences in development and growth (physiological constraints) and reproductive ecology (plasticity in reproductive traits).