Phylogeography of Sodreaninae harvestmen (Arachnida: Opiliones: Gonyleptidae): Insights into the biogeography of the southern Brazilian Atlantic Forest

Abstract

The Brazilian Atlantic Forest has long been considered a global biodiversity hotspot. In the last decade, the phylogeographic patterns of endemic taxa have been unraveling the biogeographic history of the biome. However, highly diverse invertebrate species have still been poorly studied. Sodreana harvestmen (Gonyleptidae) are distributed in most of the humid coastal forests in the southern portion of the Atlantic Forest, a region that has experienced complex topographic evolution and differing climatic conditions since the Early Cretaceous, which likely affected the geographic distribution and diversification of the group. In this study, we investigated the molecular phylogeny and phylogeography of Sodreana to clarify the species relationships and to make inferences about the historical biogeography of the southern Atlantic Forest. We applied coalescent-based phylogenetic analyses using one mitochondrial and three nuclear markers coupled with an ecological niche modeling approach to verify relationships among species, date the main divergence events in the genus, and make inferences concerning possible changes in the geographical distribution and population dynamics from the past. Our results supported the validity of most Sodreana species and suggested that Paleogene-Neogene geomorphologic processes such as the formation of rivers systems, uplift of mountain ranges and related environmental changes have profoundly affected the evolutionary history of Sodreana. The ecological niche models showed that the areas potentially occupied by the species were greatly reduced during Quaternary glacial periods but no recent lineage divergences or genetic bottlenecks were detected, suggesting that climatically stable micro-habitats could have helped maintain populations during drier periods. Our study highlights the importance of humidity-dependent and poor-dispersal taxa in understanding the effects of ancient geological and climate processes on the Atlantic Forest biota.

Keywords: Atlantic rainforest; Ecological niche modelling; Population genetics; Sodreana; Systematics; Taxonomy.