HOME >> BIOLOGY >> NEWS
Robust time estimation reconciles views of the antiquity of placental mammals

Despite great progress over the past decade, the evolutionary history of placental mammals remains controversial. While a consensus is emerging on the topology of the evolutionary tree, although with occasional disagreement, divergence times remain uncertain. The age of earlier nodes and in particular the root, remain especially uncertain in the absence of definitive placental fossils deeper into the Cretaceous. Both paleontological and morphological studies suggest that the radiation of placental orders and super orders occurred close to the CretaceousTertiary (KT) boundary about 65 million years ago (mya). In contrast, molecular studies have suggested markedly older origins for many superordinal groups and that some extant orders diversified before the KT boundary.

However, this discrepancy may not be real, but rather appear because of the violation of implicit assumptions in the estimation procedures, such as abrupt acceleration of evolutionary rate entangled with gradual variation and large-scale convergent evolution in molecular level. By their new robust procedure, Dr. Kitazoe and his collaborators identified a strong and short-term acceleration of mitochondrial genome along the lineage leading to Laurasiatheria. The revised time at the root of placental mammals was much younger than the preceding reports, 84 million years ago instead of around 122 million years ago. As a result, the estimated distribution of molecular divergence times is broadly consistent with quantitative analysis of the North American fossil record and traditional morphological views. They emphasize the necessity to scrutinize the implicit assumptions adopted by the models of molecular evolution and to develop procedures which rely little on those assumptions.


'"/>

Contact: Yasuhiro Kitazoe
kitazoey@kochi-u.ac.jp
Public Library of Science
17-Apr-2007


Page: 1

Related biology news :

1. Local range estimation in wild animals
2. Neuroblastoma expert reviews progress and challenges in fighting difficult pediatric cancer
3. New findings challenge established views on human genome
4. New findings challenge established views about human genome
5. Public shares views on environmental, health and safety research needs for nanoscale materials
6. Handling HPV vaccines and screening: The views of 100 authors
7. Through a satellite darkly: Night views of European seas improve ESA ocean heat map
8. Avian flu in perspective: New England Journal article reviews spectacular findings
9. New study into public views on diet and health research published
10. Technological revolutions in sensors, robotics, and telecommunications allow new views of ocean
11. New study highlights universality of public views toward science and technology

Post Your Comments:
*Name:
*Comment:
*Email:


(Date:7/17/2019)... ... July 18, 2019 , ... ... Meredith James, HT, PMP, to its executive team as Vice President of Operations. ... drug development. In her new role, Ms. James is responsible for ensuring on-time ...
(Date:7/17/2019)... ... 15, 2019 , ... RCH Solutions (RCH), a ... companies, announces the availability of new specialty advisory practice, a Public Cloud Managed ... emerging bio-pharma companies interested in achieving specific outcomes related to public Cloud adoption. ...
(Date:7/17/2019)... ... ... Imagine using a simple, portable test to detect cancer before malignant tissues ... South Dakota School of Mines & Technology researcher Congzhou Wang, Ph.D., these ideas are ... to monitor and prevent disease,” says Wang. , Wang, an assistant professor in ...
Breaking Biology News(10 mins):
(Date:7/11/2019)... ... July 11, 2019 , ... At the most recent stem cell ... eight military Veterans under the R3 Heroes Program. The Veterans included individuals and families ... Program allow anyone to nominate a military Veteran, teacher or first responder to receive ...
(Date:7/9/2019)... ... July 08, 2019 , ... Balluff has been ... recognized as the 2019 Innovative Product of the Year which highlights cutting-edge advancements ... during Sensors Expo & Conference 2019, held this week in San ...
(Date:6/26/2019)... ... June 26, 2019 , ... Alice Branton today released ... improving physicochemical properties of Magnesium Gluconate, which can prove to be beneficial for treating ... of characteristic differentiation peak, change in crystallite size , Over 142% increase ...
(Date:6/18/2019)... ... ... Personalized Stem Cells, Inc (“PSC”), a human adipose-derived stem cell company, ... a person’s own adipose-derived stem cells to treat their osteoarthritis. The first clinical trial ... is the first of several planned clinical trials which will enable qualified PSC-enrolled physicians ...
Breaking Biology Technology:
Cached News: