Weider and Hobæk 2000

Weider LJ, Hobæk A. 2000. Phylogeography and arctic biodiversity: a review. Annales Zoologici Fennici 37: 217-231.

These authors review a variety of phylogeographic studies, to examine the importance of dispersal, vicariance, and selection in shaping the current distributions of Arctic organisms. Much of the focus is on closely-related organisms such as species complexes and subspecies. They provide justification for studying the species-poor Arctic in three ways: 1. the Arctic consists of relatively simple ecosystems, with reduced trophic interactions; 2. Arctic ecosystems are relatively fragile, where minor perturbations have immediate and long-lasting effects; 3. the Arctic has been shaped by a recent geological history of waxing and waning of glaciers, providing a series of vicariance events and recolonization opportunities to organisms.

These authors briefly review a debate in the recent literature, discussing modes of speciation in the Arctic. Some authors have proposed the importance of vicariance and speciation of isolated small populations, while others have emphasized the long periods necessary for the evolution of reproductive isolation when populations re-contact. Both factors are probably important, with hybridization in interglacial periods playing a strong role. The botanical literature has also debated the competing hypotheses of “Nunataks” (Dahl 1987) versus “Tabula rasa” (Nordal 1987).

Most of the reviewed literature has been studies of endothermic vertebrates, with consistent evidence across examined species of episodes of population isolation followed by recontact and often hybridization. Population and subspecies structures are typically consistent with past periods of glaciation, often between 300k and 500k years ago.

The summary findings of this paper are that 1. speciation has occurred or appears to be progressing by vicariance and hybridization in the Arctic; 2. dispersal, founder effects, range expansions, secondary contacts, and other processes have structured population genetics; 3. life-cycle and breeding system optimizations have been very important as adaptations to abiotic factors.

The literature cited section is full of papers that I need to read, especially Klicka and Zink (1997) and Freckman & Virginia (1997).