Comparative phylogeography clarifies the complexity and problems of continental distribution that drove A. R. Wallace to favor islands

Abstract

Deciphering the geographic context of diversification and distributional dynamics in continental biotas has long been an interest of biogeographers, ecologists, and evolutionary biologists. Thirty years ago, the approach now known as comparative phylogeography was introduced in a landmark study of a continental biota. Here, I use a set of 455 studies to explore the current scope of continental comparative phylogeography, including geographic, conceptual, temporal, ecological, and genomic attributes. Geographically, studies are more frequent in the northern hemisphere, but the south is catching up. Most studies focus on a Quaternary timeframe, but the Neogene is well represented. As such, explanations for geographic structure and history include geological and climatic events in Earth history, and responses include vicariance, dispersal, and range contraction-expansion into and out of refugia. Focal taxa are biased toward terrestrial or semiterrestrial vertebrates, although plants and invertebrates are well represented in some regions. The use of various kinds of nuclear DNA markers is increasing, as are multiple locus studies, but use of organelle DNA is not decreasing. Species distribution models are not yet widely incorporated into studies. In the future, continental comparative phylogeographers will continue to contribute to erosion of the simple vicariance vs. dispersal paradigm, including exposure of the widespread nature of temporal pseudocongruence and its implications for models of diversification; provide new templates for addressing a variety of ecological and evolutionary traits; and develop closer working relationships with earth scientists and biologists in a variety of disciplines.biogeography | biodiversity conservation | evolutionary biology | diversification | ecology

Genetic data reveal a cryptic species of New World flying squirrel: Glaucomys oregonensis

“…Thus, despite their similar present-day geographic distributions and close association with boreal forest, the divergence of the CON and PC forms of G. sabrinus likely substantially predates the divergence of the CON and PC forms of Tamiasciurus (T. hudsonicus and T. douglasii, respectively). These findings support the hypothesis presented by Arbogast and Kenagy (2001) that the spatially similar phylogeographic patterns observed in many co-distributed North American boreal forest mammals may represent a case of "pseudocongruence" (when similar spatial patterns are formed in co-distributed taxa at different times; see Arbogast and Kenagy 2001;Riddle 2016). This is certainly plausible, as the cyclical nature of glacial-interglacial events throughout the Pleistocene would have provided many opportunities for North American boreal forest taxa to become isolated in separate "eastern" and "western" refugia during glacial maxima Hope et al 2016).…”

Comparative phylogeography of the ocean planet

“…Life began in the oceans, but the field of phylogeography began with continental biota (6,15), and many of the insights reviewed here have precedents in terrestrial cases. The biogeographic settings have parallels between land and sea, particularly with latitudinal gradients in biodiversity and concordance between biogeographic provinces and phylogeographic partitions (15,147).…”

“…The biogeographic settings have parallels between land and sea, particularly with latitudinal gradients in biodiversity and concordance between biogeographic provinces and phylogeographic partitions (15,147). Glacial habitat disruptions in northern seas have a strong parallel in continental faunas (148,149).…”

“…As in terrestrial and freshwater systems, phylogeographic comparisons among species often reveal a diversity of outcomes, attributed to the idiosyncrasies of individual taxa (14,15). However, the comparative approach can reveal insights unavailable from any one example (16), as illustrated by the terrestrial biota of Hawai'i (17).…”

In the light of evolution X: Comparative phylogeography

“…Empirical phylogeographic patterns in the sea have also illuminated the evolutionary role of biodiversity hotspots and the historical dispersal routes that enhance global biodiversity. Brett Riddle (20) summarizes an equally large scientific literature for species that occupy terrestrial or semiterrestrial regimes on continental landmasses. The author identifies phylogeographic hotspots, usually ecological transition zones that are focal points for study.…”