Retroposon analysis of major cetacean lineages: The monophyly of toothed whales and the paraphyly of river dolphins

Abstract

SINE (short interspersed element) insertion analysis elucidates contentious aspects in the phylogeny of toothed whales and dolphins (Odontoceti), especially river dolphins. Here, we characterize 25 informative SINEs inserted into unique genomic loci during evolution of odontocetes to construct a cladogram, and determine a total of 2.8 kb per taxon of the flanking sequences of these SINE loci to estimate divergence times among lineages. We demonstrate that: (i) Odontocetes are monophyletic; (ii) Ganges River dolphins, beaked whales, and ocean dolphins diverged (in this order) after sperm whales; (iii) three other river dolphin taxa, namely the Amazon, La Plata, and Yangtze river dolphins, form a monophyletic group with Yangtze River dolphins being the most basal; and (iv) the rapid radiation of extant cetacean lineages occurred some 28 -33 million years B.P., in strong accord with the fossil record. The combination of SINE and flanking sequence analysis suggests a topology and set of divergence times for odontocete relationships, offering alternative explanations for several long-standing problems in cetacean evolution.SINE ͉ evolution ͉ divergence times

Molecular systematics, phylogeny and ecology of anisakid nematodes of the genusAnisakisDujardin, 1845: an update

“…Moreover, although some Anisakis spp., such as A. ziphidarum and A. paggiae and/or A. brevispiculata are found in the same sympatric areas, as the warm temperate tropical water basin, such as the Caribbean and Florida coasts of the Atlantic Ocean, however they were never identified in the same cetacean species (Tables IV, V and Fig. 2) Phylogenetic relationships proposed elsewhere (Valentini et al, 2006) and reviewed here for species of genus Anisakis seem to align with that of their cetacean hosts (Milinkovitch, 1995;Nikaido et al, 2001) (Fig. 3).…”

“…3). The phylogeny of cetaceans proposed by Milinkovitch (1995) based on mtDNA (12S, 16S, and cytb partial sequences) and myoglobin sequences, and by Nikaido et al (2001) based on retroposon analysis indicate a branching order of the cetacean lineages where the sperm whale and the pygmy sperm whales (Physeteridae and Kogiidae) represent basal taxa, followed by the beaked whales, and freshwater and marine dolphins as the most derived ones.…”

Babesia microti-Group Parasites Compared Phylogenetically by Complete Sequencing of the CCT.ETA. Gene in 36 Isolates

“…2). In addition to delineating the genetic features of the parasites, the intron orientations disclosed in the B. microti group should prove phylogenetically meaningful in describing rare genomic changes such as indels [18,19,24], for temporal landmarks of evolution.…”

A bizarre new toothed mysticete (Cetacea) from Australia and the early evolution of baleen whales

“…This adaptive radiation was contemporaneous with global climate change, and increased productivity and heterogeneity of oceanic environments, associated with the establishment of the Antarctic Circumpolar Current following the final breakup of Gondwana and isolation of Antarctica (Fordyce 1980(Fordyce , 1992Nikaido et al 2001). Previous studies have emphasized the primacy of filter-feeding as the impetus for the initial radiation of mysticetes (Fordyce 1980;Fordyce 1992;Fordyce & Barnes 1994;Barnes et al 1995;Fordyce & Muizon 2001;Nikaido et al 2001;Berta et al 2006; but the novel morphology and basal position of Janjucetus (and Mammalodon) in mysticete phylogeny, which are both hypothesized to have not been filterfeeders, suggests that the initial radiation of mysticetes was not linked to the evolution of filter-feeding.…”