Big-brained Birds Survive Better In Nature:
Birds with brains that are large in relation to their body size have a lower mortality rate than those with smaller brains, according to new research published in the journal Proceedings of the Royal Society B: Biological Sciences. The research provides the first evidence for what scientists describe as the 'cognitive buffer' hypothesis - the idea that having a large brain enables animals to have more flexible behaviours and survive environmental challenges.
The Price Of Vanity: Mating With Showy Males May Reduce Offspring's Ability To Fight Off Pathogens:
In many animals, males advertise to potential mates with showy traits, many of which are linked to testosterone levels. However, a new study suggests that, in fish, choosing a flashier mate may cause future generations to be more susceptible to pathogens. In the January 2007 issue of The American Naturalist, a new study by Judith Mank (Uppsala University, Sweden) finds that mating with males who possess showy traits -- such as bright colors or long tails and fins -- results in higher testosterone levels in males over many generations. Because male and female testosterone levels are correlated, female choice also results in an increase in female testosterone levels.
How Are Phenotypic Differences Between Sexes Related To Phenotypic Variation Within Sexes?:
It has long been recognized that sexually dimorphic traits -- traits that are systematically different between members of different sex in the same species, such as peacocks' tail feathers -- tend to vary a great deal among individual males, and that much of this within-sex variation depends on individual condition. Indeed, theory predicts that sexual dimorphism will evolve based on condition dependence so that, among traits, a more pronounced difference between male and female should be associated with a stronger response to variation in condition.
Beavers Helping Frogs And Toads Survive:
The humble beaver, besides claiming a spot of honour on the Canadian nickel, is also helping fellow species survive. Though considered a pest because of the culvert-clogging dams it builds on streams, the beaver is an ally in conserving valuable wetland habitat for declining amphibian populations, a University of Alberta study shows.
Scientists Discover Stage At Which An Embryonic Cell Is Fated To Become A Stem Cell:
Cambridge scientists have discovered the stage at which some of the cells of a fertilised mammalian egg are fated to develop into stem cells and why this occurs. The findings of the study, which overturn the long-held belief that cells are the same until the fourth cleavage (division) of the embryo, are reported in the journal Nature.
A Curry A Day Keeps The Doctor Away?:
The chemical that gives spicy food its kick could hold the key to the next generation of anti-cancer drugs that will kill tumours with few or no side effects for the patient, say academics at The University of Nottingham. A study by the scientists, published online in the journal Biochemical and Biophysical Research Communications, has proven for the first time that the chemical compound capsaicin -- which is responsible for the burning sensation when we eat chillies -- can kill cells by directly targeting their energy source.
Controlling Sexual Compatibility Can Help Control Spread Of Some Invasive Species:
University of California, Riverside genetics Professor Norman Ellstrand led a team of researchers whose findings suggest that harnessing the sexual requirements of some plants can help control the establishment of invasive species. Using the California wild radish as their model, Ellstrand and graduate student Caroline Ridley at the UCR Department of Botany and Plant Sciences co-authored the research study titled Population size and relatedness affect fitness of self-incompatible invasive plants, published in the Dec. 29 edition of the Proceedings of the National Academy of Sciences. The current article originated from a doctoral dissertation project by former UCR graduate student Diane Elam. Fellow graduate student Karen Goodell also worked on the project. Elam is now with the U.S. Fish and Wildlife Service's Sacramento office. Karen Goodell now teaches at Ohio State University.
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