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18 juillet 2018

Adaptive radiation along a deeply conserved genetic line of least resistance in Anolis lizards [Evolution Letters]

Keywords : adaptive radiation, Anolis lizards, constraint, convergent evolution, covariance tensor analysis, G matrix, quantitative genetics, selection

On microevolutionary timescales, adaptive evolution depends upon both natural selection and the underlying genetic architecture of traits under selection, which may constrain evolutionary outcomes. Whether such genetic constraints shape phenotypic diversity over macroevolutionary timescales is more controversial, however. One key prediction is that genetic constraints should bias the early stages of species divergence along “genetic lines of least resistance” defined by the genetic (co)variance matrix, G. This bias is expected to erode over time as species means and G matrices diverge, allowing phenotypes to evolve away from the major axis of variation. We tested for evidence of this signal in West Indian Anolis lizards, an iconic example of adaptive radiation.(...)

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18 juillet 2018

Phylogenomics of montane frogs of the Brazilian Atlantic Forest is consistent with isolation in sky islands followed by climatic stability [Biological Journal of the Linnean Society]

Keywords : Brachycephalus, coalescent, Melanophryniscus, target enrichment, ultraconserved elements

Despite encompassing a relatively small geographical area, montane regions harbour disproportionately high levels of species diversity and endemism. Nonetheless, relatively little is known about the evolutionary mechanisms that ultimately lead to montane diversity. In this study, we used target capture of ultraconserved elements to investigate the phylogenetic relationships and diversification patterns of Melanophryniscus (Bufonidae) and Brachycephalus (Brachycephalidae), two frog genera that occur in sky islands of the southern Atlantic Forest of Brazil. Specifically, we tested whether diversification of montane species in these genera could be explained by a single climatic shift leading to isolation in sky islands, followed by climatic stability that maintained populations in allopatry.(...)

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18 juillet 2018

Logarithmic scales in ecological data presentation may cause misinterpretation [Nature Ecology & Evolution]

Scientific communication relies on clear presentation of data. Logarithmic scales are used frequently for data presentation in many scientific disciplines, including ecology, but the degree to which they are correctly interpreted by readers is unclear. Analysing the extent of log scales in the literature, we show that 22% of papers published in the journal Ecology in 2015 included at least one log-scaled axis, of which 21% were log–log displays. We conducted a survey that asked members of the Ecological Society of America (988 responses, and 623 completed surveys) to interpret graphs that were randomly displayed with linear–linear or log–log axes. Many more respondents interpreted graphs correctly when the graphs had linear–linear axes than when they had log–log axes : 93% versus 56% for our all-around metric, although some of the individual item comparisons were even more skewed (for example, 86% versus 9% and 88% versus 12%). (...)

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18 juillet 2018

Ecological consequences of post-Columbian indigenous depopulation in the Andean–Amazonian corridor [Nature Ecology & Evolution]

European colonization of South America instigated a continental-scale depopulation of its indigenous peoples. The impact of depopulation on the tropical forests of South America varied across the continent. Furthermore, the role that indigenous peoples played in transforming the biodiverse tropical forests of the Andean–Amazonian corridor before ad 1492 remains unknown. Here, we reconstruct the past 1,000 years of changing human impact on the cloud forest of Ecuador at a key trade route, which connected the Inkan Empire to the peoples of Amazonia. We compare this historical landscape with the pre-human arrival (around 44,000–42,000 years ago) and modern environments. We demonstrate that intensive land-use within the cloud forest before European arrival deforested the landscape to a greater extent than modern (post-ad 1950) cattle farming.(...)

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18 juillet 2018

Plasticity reveals hidden resistance to extinction under climate change in the global hotspot of salamander diversity [Science Advances]

Extinction rates are predicted to rise exponentially under climate warming, but many of these predictions ignore physiological and behavioral plasticity that might buffer species from extinction. We evaluated the potential for physiological acclimatization and behavioral avoidance of poor climatic conditions to lower extinction risk under climate change in the global hotspot of salamander diversity, a region currently predicted to lose most of the salamander habitat due to warming. Our approach integrated experimental physiology and behavior into a mechanistic species distribution model to predict extinction risk based on an individual’s capacity to maintain energy balance with and without plasticity. We assessed the sensitivity of extinction risk to body size, behavioral strategies, limitations on energy intake, and physiological acclimatization of water loss and metabolic rate.(...)

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