(Press-News.org)
Accurate phylogenetic trees are fundamental to evolutionary and comparative biology, but the almost simultaneous emergence of major animal phyla and diverse body plans during the Cambrian Explosion poses major challenges to reconstructing deep metazoan phylogenetic relationships.
This is particularly true for the second largest phylum, Mollusca, whose major lineages originated in the Cambrian period. The diverse fossil record, extreme morphological disparity among the eight living classes, and dramatic conflict among phylogenetic hypotheses due to diverse paleontological, morphological and molecular evidence hinder the understanding of molluscan phylogeny.
Recently, researchers from China, the U.S.A. and the U.K. have sequenced the first genomes of Scaphopoda or "tusk shells"—among the rarest and least-studied members of Mollusca—and found unprecedented ancient incomplete lineage sorting (ILS) that occurred during early molluscan cladogenesis.
These findings provide new insights into early molluscan evolution and explain why resolving molluscan class-level relationships has been a great challenge to evolutionary biologists.
The study was published in PNAS on Sept. 18.
The researchers resolved the longstanding debate regarding the phylogenetic placement of Scaphopoda. Scaphopods exhibit a mosaic of morphological and developmental features resembling those of other lineages, such as tentacles resembling the arms of cephalopods, a unique manner of shell ontology similar to that of bivalves, and a partially degenerated head that seemingly represents an intermediate state between bivalves ("headless") and gastropods (with a well-developed head).
These features have been variously interpreted by morphologists as evidence for different conflicting phylogenetic hypotheses, and phylogenomic studies to date have failed to confidently place Scaphopoda in the molluscan tree, thus making its phylogenetic placement a major question.
However, by taking ancient ILS into consideration, the current study has resolved the debate. Specifically, it has revealed that Scaphopoda is the sister lineage of Bivalvia (Diasoma concept), a hypothesis first proposed based on morphology 50 years ago but not supported by molecular phylogenetic studies to date.
This finding, together with careful molecular clock analysis, prompts re-interpretation of many important but controversial Cambrian fossils that show similarities to both bivalves and scaphopods. For instance, the laterally compressed Early Cambrian fossils Anabarella, Watsonella and Mellopegma are now proposed to be stem diasomes. It also provides important insights into how the unique body plans of scaphopods and bivalves evolved.
"Our work addresses the long-disputed phylogenetic placement of Scaphopoda and may revolutionize understanding of molluscan early evolution," said Dr. SONG Hao from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS), first author of the study.
The study indicates that the impact of ILS in the context of reconstructing Cambrian-age radiations is under-appreciated and thus calls for exploration of ancient ILS in the context of other recalcitrant nodes in deep metazoan phylogeny.
END
ITHACA, N.Y. – Remote workers can have a 54% lower carbon footprint compared with onsite workers, according to a new study by Cornell University and Microsoft, with lifestyle choices and work arrangements playing an essential role in determining the environmental benefits of remote and hybrid work.
The study, published in the Proceedings of the National Academy of Sciences, also finds that hybrid workers who work from home two to four days per week can reduce their carbon footprint by 11% to 29%, but working from home one day per week ...
Low socioeconomic status can negatively impact children’s health in preschool, along with their ability to follow specialized health education intervention programs, Mount Sinai researchers found in an international study focused on health promotion in schools, including those in the Harlem section of New York City. The results, published September 18 in the Journal of American College of Cardiology, stress the importance of introducing a specialized health curriculum in classrooms starting in preschool.
“This study shows that socioeconomic factors, including lower household income and education level, can negatively impact children’s health starting ...
CORVALLIS, Ore. – Oregon State University has received a $7.5 million National Institutes of Health grant to modernize a lab focused on using zebrafish to address pressing human health challenges.
The Sinnhuber Aquatic Research Laboratory, led by Distinguished Professor Robyn Tanguay, a molecular toxicologist in the College of Agricultural Sciences, exploits the unique advantages of zebrafish to protect and improve human and environmental health. Zebrafish and humans have similar developmental processes and are similar on a genomic level, ...
BINGHAMTON, N.Y. -- Standardized and overly simplistic questionnaires are only scratching the surface of what employees think of their leaders, according to new research from Binghamton University’s School of Management (SOM), and negative behavior may be slipping through the cracks.
As a result, the research finds, organizations may be missing out on critical information that could be keeping toxic leaders in positions of power.
“Instead of capturing actual leader behaviors, ratings might simply reflect whether a person likes their leader,” said Mengying ...
The key to solving the Libyan political conflict lies within the country rather than with the international community, analysis says.
Electoral and governance deadlock has been blamed for the devastating impact of the flooding in the country.
The “contentment” of the political elite and others with the status quo - given the currently limited levels of violence and the rising global prices of energy since the outbreak of Russia’s war on Ukraine - explains the general lack of a genuine commitment to relaunch the transition and electoral roadmap, ...
Researchers at the University of Chicago Medicine Comprehensive Cancer Center established “proof-of-concept” for a new treatment approach that was able to effectively treat the most aggressive forms of prostate cancer. The treatment showed complete tumor control and long-lasting survival without side effects in a mouse model of advanced prostate cancer.
These findings, which were published online September 18, 2023, in Clinical Cancer Research, warrant further investigation in human clinical trials, the researchers concluded.
Strategies to overcome resistance
“Prostate cancer in the metastatic ...
Philadelphia, September 18, 2023 – Very young children who attend child care and receive onsite meals and snacks were more likely to be food secure and in good health, and less likely to be admitted after a hospital emergency department visit than children in child care whose meals and snacks were provided from home, according to a new study in the Journal of the Academy of Nutrition and Dietetics, published by Elsevier. These potential benefits could extend beyond the children themselves to their families, including through possible reductions in stress, and to society as a whole through potentially significant healthcare cost savings.
Lead author Stephanie ...
HOUSTON – (Sept. 18, 2023) – Two Rice University scientists have received a 3-year grant from the Department of Energy (DOE) to investigate a form of carbon storage that is as little understood as it is ubiquitous: soil.
Mark Torres, an assistant professor of Earth, environmental and planetary sciences, and Evan Ramos, a postdoctoral fellow in the Torres lab, will track how key minerals form in a watershed to build a fuller picture of the processes that allow soil to store carbon as organic matter.
“Soil on Earth contains three times more carbon than the atmosphere,” Ramos said. “We ...
The National Institutes of Health has awarded $54 million over a seven-year period to the CCTSI at CU Anschutz. The grant from the National Center for Advancing Translational Sciences (NCATS) will fuel biomedical research and training across the state. This is the fourth consecutive time the NIH has funded the CCTSI since 2008 through its Clinical Translational Science Award (CTSA) program.
“This powerful grant will allow the University of Colorado to conduct leading-edge research that can directly impact health and patient care, reduce health disparities across our state and remain poised to respond to public ...
UNIST, in collaboration with Pusan National University Yangsan Hospital, has embarked on an exciting joint venture to research and develop advanced 3D printing medical device technology.
The UNIST 3D Printing Convergence Technology Center recently signed a business agreement with the Medical Device Usability Test Center at Pusan National University Yangsan Hospital. This agreement outlines their collaborative efforts in various areas, including the research and development of 3D printing-based medical devices as well as support for the commercialization of domestically developed devices.
Notably, Yangsan Pusan National University ...