Research Report: Extinction runs in the family


While global calamities, like the one that doomed most dinosaurs, forever alter the varieties of life on Earth, new research shows that it doesn’t take a catastrophe to end entire lineages.

Biologists have long suspected that the evolutionary history of species and lineages play a big role in determining their vulnerability to extinction, with some being more extinction-prone than others. To test this hypothesis, UCSD, Smithsonian Institution and University of Chicago researchers analyzed the 200-million-year-old fossil record of marine bivalves (clams, oysters, mussels and scallops), stretching from the Jurassic Period to the present, noting when each genus disappeared and whether their relatives disappeared at the same time.

On average, closely related clusters of clams vanished together more often than would be expected by chance. This points to the need to focus conservation efforts on vulnerable lineages. The findings appear in Science.

Alternative to mammogram

Breast cancer screening is based largely on age, family history and ethnicity, with annual mammograms recommended for healthy women starting at age 40. But a new study could lead to a more individualized approach to women’s breast cancer screenings, making each person’s genetic makeup a key factor in guiding how often they are tested.

The new study will assess whether a woman’s likelihood of developing breast cancer can be more accurately predicted by the presence of recently discovered common DNA variants (“mistakes,” or alternative letters in the human DNA code) that are associated with the disease. If these low-risk variants prove predictive, healthy women could be divided into different categories for breast cancer screening.

The initiative, dubbed the PINK study, is sponsored by Scripps Genomic Medicine (a program of Scripps Health), in association with the Scripps Polster Breast Care Center at Scripps Memorial Hospital La Jolla. For information about enrolling in the PINK study call (858) 554-5753.

Stemming infections

Parasitic roundworms infect more than a billion people in tropical regions and are one of the leading causes of debilitation in underdeveloped countries - a toll health officials consider equal to or greater than malaria or tuberculosis. Working with researchers in China, biologists at UCSD have uncovered the biological mechanism of a Chinese drug found effective in killing parasitic roundworms.

The discovery is important because currently there are few drugs that effectively combat parasitic roundworms. In addition, existing drugs face the threat posed by drug resistance developing in patients who are repeatedly re-infected and treated

The findings are detailed in PLoS Neglected Tropical Diseases. A video of researchers describing their results can be found at