A framework for elucidating the temperature dependence of fitness Zambian free sex chat cam for ipod no sign up
Rates of range shifts were first controlled for the effects of extrinsic drivers and then converted into binary response variables indicating whether the range limit had move upslope (contraction or expansion; value=1) or not (value=0), as illustrated at the final nodes by dark and light colours, respectively.Pies indicate the frequencies of the marginal ancestral state reconstructions of the binary variable depicting climate-induced range shifts in lower limit at the internal nodes of the tree.
Here, we used range shifts documented for stream fish to assess whether phylogenetic patterns in shifts at the leading and trailing edges along an altitudinal gradient resulted from conservatism of the traits involved in species response to climate change.
The thermal safety margins, describing the warming tolerance of organisms relative to their current thermal habitat, should thus be the principal trait driving extinctions or shifts to cooler habitats.
Additional traits underlying the ability of species to respond to climate change impacts (that is, resilience ability) may, however, delay extinction at the trailing edge or impede colonization at the leading edge, although acting in opposite directions.
Here, we investigate whether species traits and their underlying phylogenetic constraints explain altitudinal shifts at the trailing and leading edges of stream fish species ranges.
We demonstrate that these shifts are related to dissimilar mechanisms: whereas range retractions show some support for phylogenetic clustering due to a high level of conservatism in thermal safety margins, range expansions are underpinned by both evolutionarily conserved and labile traits, notably trophic position and life-history strategy, hence decreasing the strength of phylogenetic signal.
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Present-day geographical biodiversity patterns have been strongly shaped by two distinct processes affecting range dynamics: the expansions and contractions caused by Pleistocene glacial-interglacial cycles.