Vagility: The Neglected Component in Historical Biogeography

Abstract

The conceptual gap between ecological and historical biogeography is wide, although both disciplines are concerned with explaining how distributions have been shaped. A central aim of modern historical biogeography is to use a phylogenetic framework to reconstruct the geographic history of a group in terms of dispersals and vicariant events, and a number of analytical methods have been developed to do so. To date the most popular analytical methods in historical biogeography have been parsimony-based. Such methods can be classified into two groups based on the assumptions used. The first group assumes that vicariance between two areas creates common patterns of disjunct distributions across several taxa whereas dispersals and extinctions generate clade specific patterns. The second group of methods assumes that passive vicariance and within-area speciation have a higher probability of occurrence than active dispersal events and extinction. Typically, none of these methods takes into account the ecology of the taxa in question. I discuss why these methods can be potentially misleading if the ecology of the taxon is ignored. In particular, the vagility or dispersal ability of taxa plays a pivotal role in shaping the distributions and modes of speciation. I argue that the vagility of taxa should be explicitly incorporated in biogeographic analyses. Likelihood-based methods with models in which more realistic probabilities of dispersal and modes of speciation can be specified are arguably the way ahead. Although objective quantification will pose a challenge, the complete ignorance of this vital aspect, as has been done in many historical biogeographic analyses, can be dangerous. I use worked examples to show a simple way of utilizing such information, but better methods need to be developed to more effectively use ecological knowledge in historical biogeography.

Phylogenetics and biogeography of a spectacular Old World radiation of butterflies: the subtribe Mycalesina (Lepidoptera: Nymphalidae: Satyrini)

“…Dispersal into a novel area is more likely to result in allopatric speciation compared to a group with high vagility that can maintain regular geneflow [73]. Vicariance events are also more likely to result in speciation when the ancestor in question has weak dispersive powers.…”

Use of dispersal–vicariance analysis in biogeography – a critique

“…How many true vicariance events have been concealed by such analyses? The maximum number of areas a taxon can occupy is contingent on various factors, including the vagility of the taxon (Kodandaramaiah, 2009), the geological scenario, multiple ecological factors (e.g. predation pressure and abiotic factors) and chance events such as jump‐dispersals.…”

“…How acceptable is the assumption that all nodes on the phylogeny have the same maximum number of areas occupied? I demonstrate elsewhere (Kodandaramaiah, 2009), with empirical examples, how varying the costs of different kinds of dispersal can lead to more realistic inferences with dispersal–vicariance optimization.…”

Ancestral range reconstruction of Galliformes: the effects of topology and taxon sampling

“…Cracraft, 2001). However, as birds are highly vagile (Kodandaramaiah, 2009), dispersal has been viewed recently as a more likely explanation for disjunct distributions. Several large-scale molecular clock analyses (Ericson et al, 2006;Jarvis et al, 2014) are inconsistent with a major role for vicariance in establishing avian range disjunctions.…”