Tectonic blocks and molecular clocks

Abstract

Evolutionary timescales have mainly used fossils for calibrating molecular clocks, though fossils only really provide minimum clade age constraints. In their place, phylogenetic trees can be calibrated by precisely dated geological events that have shaped biogeography. However, tectonic episodes are protracted, their role in vicariance is rarely justified, the biogeography of living clades and their antecedents may differ, and the impact of such events is contingent on ecology. Biogeographic calibrations are no panacea for the shortcomings of fossil calibrations, but their associated uncertainties can be accommodated. We provide examples of how biogeographic calibrations based on geological data can be established for the fragmentation of the Pangaean supercontinent: (i) for the uplift of the Isthmus of Panama, (ii) the separation of New Zealand from Gondwana, and (iii) for the opening of the Atlantic Ocean. Biogeographic and fossil calibrations are complementary, not competing, approaches to constraining molecular clock analyses, providing alternative constraints on the age of clades that are vital to avoiding circularity in investigating the role of biogeographic mechanisms in shaping modern biodiversity.This article is part of the themed issue ‘Dating species divergences using rocks and clocks’.

Isolation of Novel Trypanosomatid, Zelonia australiensis sp. nov. (Kinetoplastida: Trypanosomatidae) Provides Support for a Gondwanan Origin of Dixenous Parasitism in the Leishmaniinae

“…By 90 MYA, Africa and South America had already separated. Multiple phylogenies suggest that Viannia emerged millions of years later (Fig 8) [3, 11, 57], implying that their divergence from other Euleishmania was not triggered by the separation of Africa and South America. The presence of the Leishmania subgenus in the New World is often discussed as a migration from the Old World to the New [58].…”

“…However, based on current evidence, an alternate scenario is proposed. Approximately 50 MYA the climate in the northern hemisphere was tropical and a series of land bridges, shallow seas and island chains connected Europe, North America and Asia [11, 59]. These land bridges were probably endemic for Leishmania and allowed movement of host and vector between the Old World and the New until approximately 35 to 33 MYA, when these bridges disappeared [45].…”

“…Alternatively, the Neotropical origins hypothesis suggests Leishmania appeared in the Neotropics between 34 and 46 MYA and was dispersed to the Nearctic by rodents (i.e. porcupines) via the Panamanian land bridge [11]. The parasites were then dispersed further, from the Nearctic to the Palaearctic via the Bering land bridge [3, 6].…”

Using dated molecular phylogenies to help reconstruct geological, climatic, and biological history: Examples from Colombia

“…This supports the hypothesis that lowland white sand areas may be where many Neotropical lineages first began to diversify(Frasier, Albert, & Struwe, 2008). The timing of this event has been much debated with most recent studies placing it in the early Miocene (e.g.,Montes et al, 2015) that has been supported by studies using dated phylogenies to suggest support for an earlier direct land connection (e.g.,Bacon et al, 2015aBacon et al, , 2015bBacon, Mora, Wagner, & Jaramillo, 2012;De Baets, Antonelli, & Donoghue, 2016;Jaramillo et al, 2017;Smith, Amei, & Klicka, 2012). A dated phylogeny of the families Bromeliaceae and Rapateaceae that are either epiphytic or largely restricted to sandstone substrates indicated that these families first evolved at low elevations in the Guayana Shield before extending their distributions more broadly throughout South America and into Africa(Givnish et al, 2004).…”

Geogenomics – integrating geology and phylogenetics to unravel the evolutionary history of Earth and its biota

“…Doing so necessitates a well-developed understanding of the assumptions and uncertainties involved in phylogenetic reconstruction, just as biogeographic calibration of phylogenies based on geological data requires explicit accommodation of dating errors and an understanding of the mode and rate of the geological processes involved (De Baets et al 2016). this need for a bi-directional flow of information suggests the value of expanded collaboration between geologists and evolutionary biologists in exploring the linkages between the evolution of life and the physical environment, and in furthering our understanding of the vital linkages between the biosphere and geosphere.…”