Relationship between river dolphins and whales

2001/03/23 Galarraga Aiestaran, Ana - Elhuyar Zientzia

• Eboluzioa
• Zoologia

The result of this study corresponds to other morphological and molecular studies. According to them, the relationship of kinship of toothed marine mammals is more complicated than previously thought. For example, toothed whales and catxalotes live in deep open ocean waters and eat squid, but according to their fossils they do not seem to have the same ancestor. On the other hand, their relationship with the dolphins of the rivers in which they live has also been questioned (Río Azul, Amazonas, Ganges, La Plata).

To illustrate the family tree, researchers at the Tokyo Technological Institute have collected DNA samples from 14 cetacean species and identified small repetitive fragments of DNA randomly mixed in the genome. Thus, they have made a sequence that separates the whale, dolphin and porpoise. It is said that the order would be catxalotes, Ganges dolphins and toothed whales, followed by the rest of the sea and river dolphins.

However, there are researchers who do not agree with what the Tokyo Institute of Technology says. For example, Christian de Muizon, a paleontologist at the National Museum of Natural History in Paris, disagrees with the location of the Ganges dolphin. Although some fossil remains of the Ganges dolphin reinforce Japanese influence, most evidence suggests that they are genetically closer to toothed whales and catxalots. In any case, Christian de Muizon believes that the results of the new research should be taken into account and that the relationships between these species should be reviewed.