Speciation timing and neotropical biodiversity: the Tertiary–Quaternary debate in the light of molecular phylogenetic evidence

Abstract

The evolutionary origin of extant species in the Neotropics, one of the most biodiverse regions of the world, has been widely debated. One hypothesis is that neotropical species emerged primarily during the Quaternary (the last approximately 2 million years), favoured by alternating glacial/interglacial climates. An opposite view proposes an older Tertiary origin linked primarily to palaeogeographical changes. Here, a thorough review of the available literature on DNA molecular dating shows that the Tertiary-Quaternary debate no longer makes sense. Indeed, the > 1400 neotropical species whose origin has been dated have appeared in a continual fashion since the late Eocene/early Oligocene (approximately 39 million years before present) to the Quaternary. Palaeogeographical mechanisms of speciation are relatively well accepted, but diversification processes linked to climate are still controversial. These results are important to unravel both the origin of present-day biodiversity patterns at both local and global scales and the genetic and environmental mechanisms involved, which are two crucial aspects for suitable biodiversity conservation strategies.

The hidden diversity of Coleodactylus amazonicus (Sphaerodactylinae, Gekkota) revealed by molecular data

“…Considering the range of evolutionary rates between 0.87% and 1.40%/Myr, a rough estimate places the divergence among lineages in the middle or late Miocene (Table 5), largely in agreement with the timing of diversification in several other South American taxa (reviewed in , and Rull, 2008). These divergence time estimates are also compatible with the major paleogeographic and paleoenvironmental changes that occurred in South America during the Neogene, such as marine incursions, the Andean orogeny, and the formation of the modern Amazon drainage system (e.g, Hoorn et al, 1995;Lovejoy et al, 1998;Lundberg et al, 1998).…”

Quaternary Climate Change was Not an Engine of Diversification in New World Bats (Chiroptera)

“…New World groups specifically (Amazonian possums and rodents, the Andean Akodon, and Atlantic Forest marsupials and rodents) all had mean sister-taxon values that placed their origins before the Quaternary (Moritz et al 2000: table 2). More recently, Rull (2008) dated the origins of approximately 1400 Neotropical taxa, mostly phylogroups, from across invertebrate and vertebrate taxonomic groups. Across all groups 50% of taxa emerged prior to the Quaternary.…”

Diversity Storage: Implications for tropical conservation and restoration

“…The key point is that tropical environments have been dynamic over the evolutionary history of plant genera alive today (see Rull, 2008Rull, , 2011. Six major glaciations of the last million years were preceded by dozens of lesser but detectable warm and cold spells (Millar and Brubaker, 2006).…”

“…Phylogenetics show relatedness of extant species based on sequence similarity, with criteria for species or ''evolutionarily significant units'' varying among investigators and phylogenies according to assumed rates of base-pair substitution (e.g. Rull, 2008). Whether substitution rates are assumed to be fixed or varied within phylogenies, the choice of what to analyze with fossil or molecular evidence usually depends on initial identification of taxonomic units identified by morphology.…”