what's the buzz

what's the buzz

Male guppies reproduce after death

A team of evolutionary biologists in Trinidad has found that male guppies continue to reproduce for at least ten months after they die, living on as stored sperm in females, who have much longer lifespans (two years) than males (three-four months).

“Populations that are too small can go extinct because close relatives end up breeding with each other and offspring suffer from inbreeding,” David Reznick, a professor of biology at the University of California, Riverside and the principal investigator of the research project, said.

“If there are stored sperm, then the real population size is bigger than the number of animals you see. Also, stored sperm can increase genetic variation in other ways,” he said.

Reznick explained that male guppies are brightly colored and very variable in coloration. Females prefer males with rare color patterns.

A dead male with a long-lost color pattern can later give birth to a son who can now be preferred by females because he is different from all other males in the population.
Because some females live so long, those sons can appear more than two generations after the father’s death.

“Adult female guppies are the strongest swimmers and now we know they are the best able to colonize new habitats,” Reznick said.

“Long term sperm storage means that a single female can colonize a new site and establish a new population that has a fair measure of genetic diversity since we have found that the older, larger females can carry the sperm of several males,” he added.

The findings are published online in the Proceedings of the Royal Society B.

Distribution of dark matter in 50 galaxy clusters measured

 A team of astronomers from Taiwan, England, and Japan have used the Subaru Telescope to measure the distribution of dark matter in fifty galaxy clusters and found that its density gradually decreases from the center of these cosmic giants to their diffuse outskirts.

This new evidence about the mysterious dark matter that pervades our universe conforms to the predictions of cold dark matter theory, known as “CDM.”

Few scientists seriously doubt the existence of dark matter, which researchers discovered almost eighty years ago. Nevertheless, astronomers cannot directly see dark matter in the night sky, and particle physicists have not yet identified a dark matter particle in their experiments.

“What is dark matter?” is a big unanswered question facing astronomers and particle physicists, especially because invisible dark matter probably makes up 85 per cent of the mass of the universe.

The current team, led by Dr. Nobuhiro Okabe (Academia Sinica, Taiwan) and Dr. Graham Smith (University of Birmingham, England), used the Subaru Prime Focus Camera (Suprime-Cam) to investigate the nature of dark matter by measuring its density in fifty galaxy clusters, the most massive objects in the universe.

The team wanted to use a large sample of galaxy clusters to find out how the density of dark matter changes from the center of a typical galaxy cluster to its outskirts.

Vitamin C helps alleviate bronchoconstriction

Taking Vitamin C may substantially reduce bronchoconstriction caused by exercise, suggested a researcher from the University of Helsinki, Finland. Exercise-induced bronchoconstriction means the transient narrowing of the airways that occurs during or after exercise.

It can cause symptoms such as cough, wheezing and the shortness of breath. Formerly, this condition was called exercise-induced asthma. Usually, the diagnosis of exercise-induced bronchoconstriction is based on a 10 percent or greater decline in forced expiratory volume in 1 second (FEV1) caused by exercise.

About 10 percent of the general population suffers from exercise-induced bronchoconstriction, but among some fields of competitive winter sports the prevalence can be up to 50 per cent.

Previously, vitamin C was found to halve the incidence of common cold episodes in people enduring heavy short-term physical stress, which indicated that vitamin C might also have other effects on people under heavy physical exertion.

Dr. Harri Hemila concluded that given the low cost and safety of vitamin C and the consistency of positive findings in three randomized trials on EIB, it seems reasonable for physically active people to test vitamin C on an individual basis if they have respiratory symptoms such as cough associated with exercise.