A study conducted by scientists at the Max Planck Institute for Ornithology in Seewiesen, Germany has shown that the male members of a sandpiper population who spend less time sleeping are more successful at mating with females and have more offspring.
The sandpiper mating season takes place during the summer in the Arctic Circle, when the sun practically never goes down. Males of the species compete to impress females by fighting with each other, defending territory, and flying over the females while making a hooting sound.(more…)
A classic study from more than 60 years ago suggesting that males are more promiscuous and females more choosy in selecting mates may, in fact, be wrong, say life scientists who are the first to repeat the historic experiment using the same methods as the original.
In 1948, English geneticist Angus John Bateman published a study showing that male fruit flies gain an evolutionary advantage from having multiple mates, while their female counterparts do not. Bateman’s conclusions have informed and influenced an entire sub-field of evolutionary biology for decades.
“Bateman’s 1948 study is the most-cited experimental paper in sexual selection today because of its conclusions about how the number of mates influences fitness in males and females,” said Patricia Adair Gowaty, a distinguished professor of ecology and evolutionary biology at UCLA. “Yet despite its important status, the experiment has never been repeated with the methods that Bateman himself originally used, until now. (more…)
EAST LANSING, Mich. — New research out of Michigan State University reveals female athletes and younger athletes take longer to recover from concussions, findings that call for physicians and athletic trainers to take sex and age into account when dealing with the injury.
The study, led by Tracey Covassin of MSU’s Department of Kinesiology, found females performed worse than males on visual memory tests and reported more symptoms postconcussion.
Additionally, high school athletes performed worse than college athletes on verbal and visual memory tests, and some of the younger athletes still were impaired up to two weeks after their injuries. (more…)
In order to accurately identify skulls as male or female, forensic anthropologists need to have a good understanding of how the characteristics of male and female skulls differ between populations. A new study from North Carolina State University shows that these differences can be significant, even between populations that are geographically close to one another.
The researchers looked at the skulls of 27 women and 28 men who died in Lisbon, Portugal, between 1880 and 1975. They also evaluated the skulls of 40 women and 39 men who died between 1895 and 1903 in the rural area of Coimbra, just over 120 miles north of Lisbon. (more…)
*Studies of diving beetles suggest sperm evolution may be driven by changes in female reproductive organs, challenging the paradigm of post-mating sexual selection being driven mostly by competition among sperm.*
Studying female reproductive tracts and sperm in diving beetles (Dytiscidae), researchers from the University of Arizona and Syracuse University have obtained a glimpse into a bizarre and amazing world of sperm that can take on a variety of forms – including joining together into conglomerates that navigate the twisted mazes of the female reproductive tract.
Analyses of the evolutionary relationships among diving beetles reveal that sperm form appears to follow function dictated by female reproductive organs. (more…)
It is well documented that male birds seduce females using their songs, colourful plumage and courtship dances. These signals reflect male genetic quality and will be graded by the female to determine a male’s potential as a mate. The stronger the grade, the better the odds of being selected.
But this basic rule isn’t the only yardstick used by females. As surprising as it seems, birds know how to use data from their social environment to maximize their chances of reproduction. Frédérique Dubois, a professor at the Université de Montréal Department of Biological Sciences, has already demonstrated that female Zebra Finches will favour a male chosen by another female. Dubois refers to this as imitation and the use of “public information” in choosing a mate. (more…)
*Females influence the gender of their offspring so they inherit either their mother’s or grandfather’s qualities. ‘High-quality’ females – those which produce more offspring – are more likely to have daughters.*
*Weaker females, whose own fathers were stronger and more successful, produce more sons.*
The study, by scientists at the University of Exeter (UK), Okayama University and Kyushu University (Japan), is published today (9 January) in the journal Ecology Letters. It shows for the first time that females are able to manipulate the sex of their offspring to compensate for the fact that some of the genes which make a good male make a bad female and vice versa.
The research focuses on the broad-horned flour beetle, Gnatocerus cornutus, but the team believes the findings could apply to other species across the animal kingdom, even mammals. (more…)
*Researchers find that being at the top may come at a high cost*
Ecologists at Princeton University recently discovered top-ranking male baboons exhibit higher levels of stress hormones than second-ranking males, suggesting that being at the top of a social hierarchy may be more costly than previously thought. (more…)
