Time filter

Source Type

Portillo F.,University of Texas at El Paso | Greenbaum E.,University of Texas at El Paso | Menegon M.,Sezione di Zoologia dei Vertebrati | Maximilian Dehling J.,University of Koblenz-Landau
Molecular Phylogenetics and Evolution | Year: 2015

The genus Leptopelis occurs in multiple habitats throughout sub-Saharan Africa, and it includes several species that have highly variable color patterns, which makes taxonomic studies challenging In this study, we examined multiple populations of Leptopelis from the Albertine Rift (AR), a region known for its high levels of endemism and biodiversity Currently, five species are recognized from the AR: L anebos, L fiziensis, L karissimbensis, L kivuensis, and L mtoewaate, most of which are found in and around the Itombwe Plateau in Democratic Republic of the Congo (DRC) We sampled 90 individuals of Leptopelis from multiple localities in DRC, Uganda, Rwanda and Burundi We employed concatenated gene-tree analyses, coalescent species-tree analyses, and divergence dating approaches to infer phylogenies and biogeographic patterns with a multi-locus data set consisting of two mitochondrial ( 16S and cyt b) and one nuclear gene ( RAG1) All analyses revealed several cryptic lineages within the genus, suggesting that a revision of AR Leptopelis taxonomy is needed. © 2014 Elsevier Inc. Source

Loader S.P.,University of Basel | Gower D.J.,Natural History Museum in London | Ngalason W.,University of Dar es Salaam | Menegon M.,Sezione di Zoologia dei Vertebrati
Zoological Journal of the Linnean Society | Year: 2010

Material ascribed to the genus Callulina from north-east Tanzania and south-east Kenya is assessed. Three new species of Callulina are described from the North (Callulina laphami sp. nov.) and South (Callulina shengena sp. nov. and Callulina stanleyi sp. nov.) Pare Mountains in Tanzania. The species are diagnosed based on morphological, acoustic, and molecular data. A new key to the species of Callulina is provided. Based on an interpretation of the International Union for Conservation of Nature (IUCN) red list, we suggest that the three species will qualify as critically endangered, because of their small distributions and the ongoing threat to their habitat. We reveal the high local endemism of Callulina in the northern part of the Eastern Arc Mountains, with each species restricted to no more than one mountain (fragment) block. This high local endemism in Callulina is probably widespread across the Eastern Arc, raising further conservation concern for this group of amphibians. Based on new molecular phylogenetic data for Callulina, we discuss biogeographical relationships among north-east Tanzanian mountains, and evolutionary patterns in Eastern Arc breviciptids. © 2010 The Linnean Society of London. Source

Brambilla M.,Sezione di Zoologia dei Vertebrati | Gobbi M.,Sezione di Zoologia degli Invertebrati e Idrobiologia
Ecography | Year: 2014

Climate change is affecting species distribution, composition of biological communities, and species traits. Despite the growing body of knowledge on the reaction of species to climate change, the potentially delayed response of species is still severely understudied. In this paper we modelled the time needed by ground-living invertebrates to effectively react to habitat modification induced by climate change in relation to dispersal abilities. We analyzed the occurrence pattern of alpine ground beetles (carabids) along areas recently freed by retreating glaciers in the central-eastern Italian Alps, to test how the synergic effects of time since deglaciation and environmental factors may affect the colonisation process. Different times of response to climate change in ground beetles were found. Sites already hosting the land cover type suitable for our study taxon, but ice-free for less than 100 yr, are mainly colonised by winged carabid beetles (which have high dispersal abilities and are mostly habitat generalists). No, or very few, wingless species (slow colonizers and ecologically specialized) occur within those sites. The overall pattern suggests that within a site, suitable land cover is established prior to colonization, due to a strong joint effect of time since deglaciation and land cover type. Long-lasting habitat development at the fine scale is likely to result in a lack of specific resources (e.g. food items, or microhabitat), which is likely to contribute to delayed colonisation, which potentially could be tied also to dispersal abilities. Whatever the reason, the existence of a time-lag often equal to or greater than 100 yr in species colonisation implies caution in predicting species' occurrence shifts following climate change. © 2013 The Authors. Source

Loader S.P.,University of Basel | Loader S.P.,Natural History Museum in London | Wilkinson M.,Natural History Museum in London | Cotton J.A.,Queen Mary, University of London | And 8 more authors.
Herpetological Journal | Year: 2011

Phylogenetic relationships of the East African caeciliid Boulengerula were reconstructed using 12S, 16S and cytb mitochondrial gene sequences for 32 samples from Kenya and Tanzania. The generally well-supported and resolved phylogeny displayed the following relationships among the five nominate species sampled: (B. boulengeri ((B. taitanus, B. niedeni), (B. changamwensis, B. uluguruensis))). This resolution supports a formerly proposed bipartition of the genus, and differs significantly from previous, morphological phylogenies. Our analyses identified genetic differences between several mtDNA clades that potentially represent undescribed species. If substantiated, the necessary taxonomic revision will have implications for conservation assessments that depend to an important extent upon sizes of distributions. Overall, there is a positive correlation between genetic and geographic distance among and within the main clades. The two lowland, coastal individuals sampled are nested within primarily montane clades. Dating analyses suggest some temporally congruent divergences in Boulengerula, but other divergences happened at different times and over a long period, perhaps extending back to the Oligocene/Eocene. Our results for Boulengerula suggest a role for relative long-term environmental stability in the origins of the Eastern Arc Mountains biodiversity hotspot. Source

Tenan S.,Sezione di Zoologia dei Vertebrati | Maffioletti C.,Sezione di Zoologia degli Invertebrati e Idrobiologia | Caccianiga M.,University of Milan | Compostella C.,University of Milan | And 2 more authors.
Ecological Modelling | Year: 2016

Chronosequences of glacier retreat are useful for investigating primary successions over time periods that are longer than direct observation would permit. In this context, space-for-time substitution studies have been applied to assess the effects of climate change on invertebrate assemblages. However, population dynamics of insect species following retreating glaciers has been under-investigated until now due to difficulty in applying capture-recapture methods and correctly identifying species in the field. Removal sampling methods are commonly used, but imperfect detectability is rarely accounted for in the analytical framework. In this paper we study the effects of environmental drivers of spatial, and indirectly temporal, variation in population size and sex-ratio of cold-adapted insects through a hierarchical framework for abundance. We show the importance of a metapopulation design, where samples are replicated in space and time, to model data from small and scattered populations, typically present in habitats with climate-mediated selective pressure like those along glacier forelands. This scattered distribution can influence the observation or sampling process and thus species detectability. Our results show that glacier retreat differently affects species-specific changes of population size and sex ratio along the chronosequence, even if the species are taxonomically related. Small-sized populations occur on the glacier surface, near the glacier front, and in sites deglaciated for at least 100 yrs. On the contrary, larger populations occupy sites deglaciated for more than 20 yrs, but less than 100 yrs. This pattern is described by the concave relationship of abundance with both species richness of other arthropods (proxy of habitat complexity) and soil organic matter (proxy of soil maturity). Sex-ratio showed opposite patterns in relation to time since deglaciation. Hierarchical models that estimate abundance of spatially distinct subpopulations represent useful tools for accurately assessing changes in species abundance following climate change while accounting for possible bias associated with imperfect detectability, an issue which is often neglected in space-for-time substitution studies on invertebrates and, more generally, in studies involving pitfall trapping. © 2016 Elsevier B.V. Source

Discover hidden collaborations