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Fig. 4 | Evolution: Education and Outreach

Fig. 4

From: Historical Biogeography: Evolution in Time and Space

Fig. 4

Parametric, time-based reconstruction of the biogeographic history of ratites. a Range evolution is modeled as a stochastic process (“Markov chain”) that evolves along the branches of a phylogeny from ancestor to descendants as a function of time. The Markov process is governed by a matrix of transition probabilities (a) that determines the rate of change between geographic states (here the geographic ranges A, B, and AB), and whose parameters are biogeographic processes such as range expansion (DAB) and area-related extinction (EA). Given this model (a) and a time-calibrated phylogeny with molecular estimates for lineage divergence times (b, adapted from Pereira and Baker 2006), it is possible to reconstruct the spatio-temporal evolution of the group (c) by using a parametric biogeographic method such as Dispersal–Extinction–Cladogenesis (Ree et al. 2005). The parametric reconstruction (c) shows the most likely range inheritance scenario at each cladogenetic event; that is, how the ancestral range became divided between the two descendants at speciation; for example, “NZ/Gondwana” indicates diversification within New Zealand when this area was still part of East Gondwana (formed by AFR, NZ, SAM, AUS, and NG), while “NZ/AUS-NG” indicates vicariance between NZ and Australia-New Guinea. Abbreviations as in Fig. 1

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