Do phylogenetic lineages preferentially ’fall into’ the tropics?
Public Science-i Team
active 6 days ago
Array Science-i Team
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One of the biggest mysteries of ecology is the latitudinal diversity gradient. Many mechanisms have been suggested. We want to put one of them to the test, for trees. We are interested by the idea that it is harder for a lineage to produce new clades that live out away from the tropics, because that takes special adaptations (e.g. seasonal dormancy, freezing tolerance, high temperature event tolerance, drought tolerance etc.). Iyt will be much easier for lineages to branch back into the tropics, simply by losing those special adaptations. So the tropics are continually being supplied with new lineages from outside, as well as the locally produced ones, adding to tropical diversity. In this project, we will compare tree community composition from standard plots at various latitudes / points on environmental stress gradients, globally. The bar coded phylogenetic positions of tree genera living outside the tropics and in the tropics will be compared (actually along continua of temperature, rainfall etc.). We predict that the extratropical tree lineages descend from relatively few founding events when lineages left the tropics. By contrast, we predict, many of those extratropical lineages will be found to have produced tropical lineages when they branched back into the tropics. This will be evidence of the ‘one way filter’ that increases the latitudinal contrast in diversity.