Evidence from milk casein genes that cetaceans are close relatives of hippopotamid artiodactyls.

نویسندگان

  • J Gatesy
  • C Hayashi
  • M A Cronin
  • P Arctander
چکیده

The inferred transition from terrestrial hoofed mammal to fully aquatic cetacean has been intensively studied with fossil evidence. However, large sections of this remarkable evolutionary sequence are missing. Phylogenetic analysis of extant taxa may help to fill in some of these gaps. In this report, kappa-casein (exon 4) and beta-casein (exon 7) milk protein genes from cetaceans and other placental mammals were PCR-amplified, sequenced, and aligned to previously published sequences. Phylogenetic analyses of the casein data suggest that hippopotamid artiodactyls are more closely related to cetaceans than to other artiodactyls (even-toed hoofed mammals). An analysis of the nuclear casein sequences combined with published mitochondrial cytochrome b DNA sequences also supports the Cetacea/Hippopotamidae sister group. This affinity implies that some of the aquatic traits of cetaceans were derived in the common ancestor of Cetacea and Hippopotamidae. An extant "missing link" to Cetacea may have been overlooked by science since the description of the semiaquatic Hippopotamus in 1758. Paleontological information is grossly inconsistent with this hypothesis. If the casein phylogeny is accurate, large gaps in the fossil record as well as extensive morphological reversals and convergences must be acknowledged.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

More DNA support for a Cetacea/Hippopotamidae clade: the blood-clotting protein gene gamma-fibrinogen.

Recent phylogenetic analyses of DNA sequences suggest that cetaceans (whales) and hippopotamid artiodactyls (hippos) are extant sister taxa. Consequently, the shared aquatic specializations of these taxa may be synapomorphies. This molecular view is contradicted by paleontological data that overwhelmingly support a monophyletic Artiodactyla (even-toed ungulates) and a close relationship between...

متن کامل

O-44: Characterisation of Monotreme CaseinsReveals Lineage Specific Expansion of an AncestralCasein Locus in Mammals

Background: One important reproductive characteristic of Mammals is the production of milk to nurse the neonate. In order to better understand the evolution of milk we have investigated gene expression in milk cells from monotremes which are the most ancient representative of the mammalian lineage. Materials and Methods: Using a milk cell cDNA sequencing approach we characterise milk protein se...

متن کامل

Infrasonic and Ultrasonic Hearing Evolved after the Emergence of Modern Whales.

Mysticeti (baleen whales) and Odontoceti (toothed whales) today greatly differ in their hearing abilities: Mysticeti are presumed to be sensitive to infrasonic noises [1-3], whereas Odontoceti are sensitive to ultrasonic sounds [4-6]. Two competing hypotheses exist regarding the attainment of hearing abilities in modern whales: ancestral low-frequency sensitivity [7-13] or ancestral high-freque...

متن کامل

Molecular evidence for the inclusion of cetaceans within the order Artiodactyla.

The transition in the cetaceans from terrestrial life to a fully aquatic existence is one of the most enduring evolutionary mysteries. Resolving the phylogenetic relationships between Cetacea and the other orders of eutherian mammals may provide us with important clues to the origin of whales and may help us date the evolutionary transition to aquatic life. Previous paleontological and molecula...

متن کامل

Ankle morphology of the earliest Cetaceans and its implications for the phylogenetic relations among ungulates.

Recent molecular studies are inconsistent with ungulate phylogenetic trees that are based on morphological traits. These inconsistencies especially relate to the position of cetaceans and perissodactyls. Evaluation of the close phylogenetic ties between artiodactyls and cetaceans has been hampered by the absence of tarsal bones of primitive cetaceans, as artiodactyls are often diagnosed on the ...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Molecular biology and evolution

دوره 13 7  شماره 

صفحات  -

تاریخ انتشار 1996