Divergence date estimation and a comprehensive molecular tree of extant cetaceans

McGowen, Michael R.; Spaulding, Michelle; Gatesy, John

doi:10.1016/j.ympev.2009.08.018

Cited by 348 publications

(525 citation statements)

References 91 publications

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“…Later microchiropteran bat fossils show a dramatic increase in the relative size of their cochleae, similar to modern species, suggesting that the use of ultrasonic echolocation in this group developed less than 50 Ma ago. Microchiropteran prestins also evolved rapidly during this time and, as noted, developed characteristic molecular features that also evolved independently in toothed whales, whose evolution began much later (about 35 Ma ago;McGowan et al 2009;Zhou et al 2011). These whales were large, of course, but were able to use high frequencies because, as water dwellers, they were able to abandon their "land-lubber" middle ear (Nummela et al 2007), whose frequency response is strongly correlated with body size.…”

Section: When Did Mammals Develop High-frequency and Ultrasonic Hearing?mentioning

confidence: 82%

Evolutionary Paths to Mammalian Cochleae

Manley

2012

JARO

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Evolution of the cochlea and high-frequency hearing (920 kHz; ultrasonic to humans) in mammals has been a subject of research for many years. Recent advances in paleontological techniques, especially the use of micro-CT scans, now provide important new insights that are here reviewed. True mammals arose more than 200 million years (Ma) ago. Of these, three lineages survived into recent geological times. These animals uniquely developed three middle ear ossicles, but these ossicles were not initially freely suspended as in modern mammals. The earliest mammalian cochleae were only about 2 mm long and contained a lagena macula. In the multituberculate and monotreme mammalian lineages, the cochlea remained relatively short and did not coil, even in modern representatives. In the lineage leading to modern therians (placental and marsupial mammals), cochlear coiling did develop, but only after a period of at least 60 Ma. Even Late Jurassic mammals show only a 270°cochlear coil and a cochlear canal length of merely 3 mm. Comparisons of modern organisms, mammalian ancestors, and the state of the middle ear strongly suggest that high-frequency hearing (920 kHz) was not realized until the early Cretaceous (~125 Ma). At that time, therian mammals arose and possessed a fully coiled cochlea. The evolution of modern features of the middle ear and cochlea in the many later lineages of therians was, however, a mosaic and different features arose at different times. In parallel with cochlear structural evolution, prestins in therian mammals evolved into effective components of a new motor system. Ultrasonic hearing developed quite late-the earliest bat cochleae (~60 Ma) did not show features characteristic of those of modern bats that are sensitive to high ultrasonic frequencies.

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Section: When Did Mammals Develop High-frequency and Ultrasonic Hearing?mentioning

confidence: 82%

Evolutionary Paths to Mammalian Cochleae

Manley

2012

JARO

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“…Previously, Meredith et al [16] calculated a rate of 0.0081 frameshifts kb 21 myr 21 for neutrally evolving mysticete DNA. Assuming this rate, and a stem mysticete branch that comprises 7.6 myr of evolutionary history [38], then we should expect only 0.24 shared frameshifts per 3.9 kb for exonic segments that have evolved under neutral evolution.…”

Section: Resultsmentioning

confidence: 98%

“…Given that none of the highest supported nodes (.70%) on the MMP20 tree conflicted with cetartiodactyl species trees (see below), and that differences pertain to nodes that are weakly supported by MMP20 alone and typically require larger datasets to achieve improved resolution, we employed a composite species tree based on McGowen et al [38] for relationships within Mysticeti, and Gatesy [39] for relationships among other cetartiodactyl taxa. The branch model of PAML [37] was used to estimate v values for functional and pseudogenic branches following Meredith et al's [16] branch-coding method.…”

Section: Methodsmentioning

confidence: 99%

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

et al. 2010

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Whales in the suborder Mysticeti are filter feeders that use baleen to sift zooplankton and small fish from ocean waters. Adult mysticetes lack teeth, although tooth buds are present in foetal stages. Cladistic analyses suggest that functional teeth were lost in the common ancestor of crown-group Mysticeti. DNA sequences for the tooth-specific genes, ameloblastin (AMBN), enamelin (ENAM) and amelogenin (AMEL), have frameshift mutations and/or stop codons in this taxon, but none of these molecular cavities are shared by all extant mysticetes. Here, we provide the first evidence for pseudogenization of a tooth gene, enamelysin (MMP20), in the common ancestor of living baleen whales. Specifically, pseudogenization resulted from the insertion of a CHR-2 SINE retroposon in exon 2 of MMP20. Genomic and palaeontological data now provide congruent support for the loss of enamel-capped teeth on the common ancestral branch of crown-group mysticetes. The new data for MMP20 also document a polymorphic stop codon in exon 2 of the pygmy sperm whale (Kogia breviceps), which has enamel-less teeth. These results, in conjunction with the evidence for pseudogenization of MMP20 in Hoffmann's two-toed sloth (Choloepus hoffmanni), another enamel-less species, support the hypothesis that the only unique, non-overlapping function of the MMP20 gene is in enamel formation.

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“…The oldest record for a crown ziphiid is a small berardiine from the Middle Miocene (late Langhian to early Serravallian, 15-13.2 Ma) of the North Sea [6,46] (figure 4); although from platform deposits, this record provides a minimum date for the emergence of deep diving in ziphiids, still younger than some (but not all) molecular divergence date estimates provided form Crown Ziphiidae [47][48][49]. On the other hand, the locality of the youngest stem ziphiid (Ninoziphius platyrostris, Sud-Sacaco, Sacaco Basin, Peru; Muizon, 1984 [44]) was recently re-dated to the Late Miocene (possibly early Messinian [50]).…”

Section: (B) Broader Palaeoecological Outcomementioning

confidence: 95%

“…On the other hand, the locality of the youngest stem ziphiid (Ninoziphius platyrostris, Sud-Sacaco, Sacaco Basin, Peru; Muizon, 1984 [44]) was recently re-dated to the Late Miocene (possibly early Messinian [50]). The extinction of stem ziphiids may thus be roughly synchronous with the Late Miocene appearance and early diversification of modern delphinoid families, including delphinids for which divergence date estimates fall within the Tortonian or-a less likely result considering the fossil record-the latest Messinian [47][48][49][51][52][53]. If, as proposed above, stem ziphiids were predominantly feeding on epipelagic prey, then they may have entered into competition with delphinids for the resources available there, unlike deepsea crown ziphiids.…”

Section: (B) Broader Palaeoecological Outcomementioning

confidence: 99%

No deep diving: evidence of predation on epipelagic fish for a stem beaked whale from the Late Miocene of Peru

et al. 2015

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Although modern beaked whales (Ziphiidae) are known to be highly specialized toothed whales that predominantly feed at great depths upon benthic and benthopelagic prey, only limited palaeontological data document this major ecological shift. We report on a ziphiid-fish assemblage from the Late Miocene of Peru that we interpret as the first direct evidence of a predator-prey relationship between a ziphiid and epipelagic fish. Preserved in a dolomite concretion, a skeleton of the stem ziphiid Messapicetus gregarius was discovered together with numerous skeletons of a clupeiform fish closely related to the epipelagic extant Pacific sardine (Sardinops sagax). Based on the position of fish individuals along the head and chest regions of the ziphiid, the lack of digestion marks on fish remains and the homogeneous size of individuals, we propose that this assemblage results from the death of the whale (possibly via toxin poisoning) shortly after the capture of prey from a single school. Together with morphological data and the frequent discovery of fossil crown ziphiids in deep-sea deposits, this exceptional record supports the hypothesis that only more derived ziphiids were regular deep divers and that the extinction of epipelagic forms may coincide with the radiation of true dolphins.

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Divergence date estimation and a comprehensive molecular tree of extant cetaceans

Cited by 348 publications

References 91 publications

Evolutionary Paths to Mammalian Cochleae

Evolutionary Paths to Mammalian Cochleae

Pseudogenization of the tooth gene enamelysin (MMP20) in the common ancestor of extant baleen whales

No deep diving: evidence of predation on epipelagic fish for a stem beaked whale from the Late Miocene of Peru

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