Species richness patterns and phylogenetic ecological niche conservatism in the Mexican Transition Zone: evidence and tools for their study

Richness patterns result from the geographic overlap of multiple species' ecological niches. Phylogenetic niche conservatism and dispersal are essential processes for understanding species richness patterns. We update the theory on the biotic assembly of the Mexican Transition Zone (MTZ) by including the phylogenetic niche conservatism concept. This theory refers to the concept of cenocron (pool of lineages of the same biogeographic affinity, sharing the same history and time of dispersal) to explain species richness gradients. We review the phylogenetic niche conservatism foundations, the statements of the MTZ theory on biotic assembly, and their relationship to other hypotheses proposed to explain geographical richness gradients to compare the predictions derived for the MTZ gradients. We present a guide of methodological possibilities to assess phylogenetic niche conservatism by applying the phylogenetic comparative method. We provide an overview of the available techniques and software, how to input the data and other requisites for their implementation and show examples of their application in the MTZ.