Speciation durations and Pleistocene effects on vertebrate phylogeography

Abstract

An approach applied previously to avian biotas is extended in this paper to other vertebrate classes to evaluate Pleistocene phylogeographic e¡ects and to estimate temporal spans of the speciation process (speciation durations) from mitochondrial (mt) DNA data on extant taxa. Provisional molecular clocks are used to date population separations and to bracket estimates of speciation durations between minimum and maximum values inferred from genetic distances between, respectively, extant pairs of intraspeci¢c phylogroups and sister species. Comparisons of genetic-distance trends across the vertebrate classes reveal the following: (i) speciation durations normally entail at least two million years on average; (ii) for mammals and birds, Pleistocene conditions played an important role in initiating phylogeographic di¡erentiation among now-extant conspeci¢c populations as well as in further sculpting pre-existing phylogeographic variety into many of today's sister species; and (iii) for herpetofauna and ¢shes, inferred Pleistocene biogeographic in£uences on present-day taxa di¡er depending on alternative but currently plausible mtDNA rate calibrations.

Dissecting the species–energy relationship

“…First, Britain has been subject to frequent glaciation periods during which most species would have been displaced further south. Moreover, speciation in Britain could only have occurred during the interglacial periods and these were typically much shorter, approximately 25,000 years (Adams et al 1999), than the time typically required for avian speciation, which has been estimated at between 250,000 and two million years (Avise et al 1998;Johnson & Cicero 2004). Second, most species breeding in Britain have large geographic ranges covering Europe, and often parts of Asia and/or Africa (Gregory & Blackburn 1998); it would be rather remarkable if the majority of these species evolved in the same small area of their distribution.…”

Global population structure of the stable fly (Stomoxys calcitrans) inferred by mitochondrial and nuclear sequence data

“…This period is characterized by repeated glaciation events, leading to drastic changes in the vegetation composition within different biomes. Avise et al (1998) reported that among major intraspecific phylogroups identified in the mammals, herpetofauna and fishes, population divergence times fall within the Pleistocene.…”

Geography and host biogeography matter for understanding the phylogeography of a parasite

“…The level of genetic divergence for H. polygyrus cyt b gene was estimated to 3.5-3.7% K 2 P (Kimura' s two parameter distance estimator) distance per million years. Genetic divergence was estimated in K 2 P distances to allow comparison with most of the published phylogeographic studies (e.g., see Avise et al, 1998), and was corrected for ancestral mtDNA polymorphism (Edwards and Beerli, 2000). This estimation was used in this study to infer the isolation epoch of the new parasite genetic lineages (Polish, Turkish and Moroccan).…”