Prediction of phylogeographic endemism in an environmentally complex biome

Abstract

Phylogeographic endemism, the degree to which the history of recently evolved lineages is spatially restricted, reflects fundamental evolutionary processes such as cryptic divergence, adaptation and biological responses to environmental heterogeneity. Attempts to explain the extraordinary diversity of the tropics, which often includes deep phylogeographic structure, frequently invoke interactions of climate variability across space, time and topography. To evaluate historical versus contemporary drivers of phylogeographic endemism in a tropical system, we analyse the effects of current and past climatic variation on the genetic diversity of 25 vertebrates in the Brazilian Atlantic rainforest. We identify two divergent bioclimatic domains within the forest and high turnover around the Rio Doce. Independent modelling of these domains demonstrates that endemism patterns are subject to different climatic drivers. Past climate dynamics, specifically areas of relative stability, predict phylogeographic endemism in the north. Conversely, contemporary climatic heterogeneity better explains endemism in the south. These results accord with recent speleothem and fossil pollen studies, suggesting that climatic variability through the last 250 kyr impacted the northern and the southern forests differently. Incorporating sub-regional differences in climate dynamics will enhance our ability to understand those processes shaping high phylogeographic and species endemism, in the Neotropics and beyond.

Vicariance and marine migration in continental island populations of a frog endemic to the Atlantic Coastal forest

“…A recent large-scale biogeographic study of T. taophora and its sister species T. miliaris showed high levels of phylogenetic diversification in these species likely due to past climatic oscillations, topographic complexity and the heterogeneity of habitats in the Atlantic Coastal Forest (Fitzpatrick et al, 2009;Carnaval et al, 2014). That study found that populations in Juréia were genetically isolated and diverged early in the history of remaining T. taophora populations (Fitzpatrick et al, 2009).…”

Tropical Refuges with Exceptionally High Phylogenetic Diversity Reveal Contrasting Phylogenetic Structures

“…CD and BCF are historical refuges for plants in two different floristic domains. CD is considered a refuge for grasslands during interglacial periods (e.g., [34,67,68]) or for firesensitive lineages after the expansion of the fire-prone Cerrado in Central Brazil [36,66], whereas BCF is a refuge for forest associated lineages [40]. These plant refuges shelter an exceptionally high PD, which is phylogenetically clustered in CD but overdispersed in BCF.…”

“…It is floristically influenced by seasonally dry forests from the surrounding Caatinga but is also home of palaeomicroendemics [35] and was recently postulated as a historical refuge for fire-sensitive lineages [36]. The Bahia Costal Forest (BCF) ecoregion [37] is the largest area of climatic stability in the northern block of the Atlantic Forest [38][39][40]. Ranging from northern Espirito Santo to southern Bahia, it is dominated by evergreen forests, harbouring a forest refuge, with high levels of endemism [41] and one of the highest tree species densities in the world [42].…”

Inferring responses to climate dynamics from historical demography in neotropical forest lizards

“…Models of the paleodistribution of the species were derived with snapshot simulations of climate spanning the last 70 ky (at 1-ky time intervals back up to 22 kya, and before that at 2-ky time intervals, with 46 time periods in total) derived from the Hadley Centre Climate model (HadCM3) (50,51). To project species ranges and genetic diversity under future climates, we used bioclimatic variables estimated from the Hadley Center model for the years 2030, 2050, 2070, and 2080 (HadGEN2-ES) (32), which is based on the RCP 6.0 emission scenario (31).…”