Historical biogeography and phylogeny of monachine seals (Pinnipedia: Phocidae) based on mitochondrial and nuclear DNA data

Abstract

Aim To determine the origin and diversification of monachine seals using a phylogenetic framework. Methods Molecular sequence data from three mitochondrial genes (cyt b, ND1 and 12S), and one nuclear marker (an intron from the α‐lactalbumin gene) were examined from all extant species of monachine seals. Maximum likelihood and partitioned Bayesian inference were used to analyse separate and combined (mitochondrial + nuclear) data sets. Divergence times were estimated from the resultant phylogeny using nonparametric rate smoothing as implemented by the program r8s. Results Mirounga, Monachus and the Lobodontini form three well‐supported clades within a monophyletic Monachinae. Lobodontini + Mirounga form a clade sister to Monachus. Molecular divergence dates indicate that the first split within the Monachinae (Lobodontini + Mirounga clade and Monachus) occurred between 11.8 and 13.8 Ma and Mirounga, Monachus and the Lobodontini originated 2.7–3.4, 9.1–10.8 and 10.0–11.6 Ma, respectively. Main conclusions Two main clades exist within Monachinae, Monachus and Lobodontini + Mirounga. Monachus, a warm water clade, originated in the North Atlantic and maintained the temperate water affinities of their ancestors as they diversified in the subtropic regions of the Northern Hemisphere. The cold‐water clade, Lobodontini + Mirounga, dispersed southward to the cooler climates of the Southern Hemisphere. The Lobodontini continued south until reaching the Antarctic region where they diversified into the present‐day fauna. Mirounga shows an anti‐tropical distribution either reflective of a once cosmopolitan range that was separated by warming waters in the tropics or of transequatorial dispersal.

Re-Evaluation of Morphological Characters Questions Current Views of Pinniped Origins

“…Th e Fyler et al (2005) molecular sequence study supports pinniped monophyly, but found that the presence of fossil Monachinae (Pristiphoca and Pliophoca) in Europe, and their exclusion in other localities with abundant phocid remains, supports de Muizon's (1982) theory of evolution of this clade in the Tethys Sea and Koretsky and Barnes' (2006) east to west dispersal hypothesis. Th e Ärnason et al (2006) molecular study suggested that pinnipeds originated on the North American continent with early otarioid and otariid divergences taking place in the North Pacifi c and those of phocids in the coastal areas of North Atlantic for later dispersal to colder environments in the Arctic Basin and in Antarctic waters.…”

Multiple markers and multiple individuals refine true seal phylogeny and bring molecules and morphology back in line

“…Molecules strongly disagree with morphology, placing the leopard and Weddell seals together (figure 1), but vary in placing the crabeater (Fyler et al 2005;Higdon et al 2007) or Ross (Davis et al 2004;Á rnason et al 2006;Fulton & Strobeck 2006) seal as most basal. AFLP analysis (Dasmahapatra et al 2009) supported the same two sister groupings as recovered here.…”

Pinniped phylogenetic relationships inferred using AFLP markers

“…Relationships within the Lobodontini have traditionally been contentious. Morphological analyses fail to find adequate resolution (BinindaEmonds and Russell, 1996), and although some molecular studies support an O. rossii, L. carcinophagus and L. weddelli, H. leptonyx relationship (Arnason et al, 2006;Fulton and Strobeck, 2006), others support L. carcinophagus as sister to the remaining taxa (Fyler et al, 2005;Higdon et al, 2007). In all cases, support for these different scenarios has been weak.…”