Month: May 2016

(credit: StatCounter)

Firefox has gingerly pulled ahead of Microsoft’s Internet Explorer and Edge browsers for the first time across the globe.

Mozilla’s Firefox grabbed 15.6 percent of worldwide desktop browser usage in April, according to the latest numbers from Web analytics outfit StatCounter.

However, neither browser threatens the market leader—Google’s Chrome continues to command two thirds of the market.

Bees work with nectar over their wax honey pots in a laboratory colony of Bombus impatiens. University of Texas, Austin, Texas, USA. (credit: Alexander Wild)

It would seem that almost every possible mating arrangement exists in the animal kingdom, from lions with their prides and ants with their colonies, to cheating birds and monogamous voles. But new research reveals that social animals have only two basic options when it comes to reproduction. They can be monogynous like ants, with only one female who mates; or they can be polygynous like chimps, with many females who mate. Depending on which evolutionary trajectory the animals follow, their population size will either grow into the millions or remain relatively small.

How many breeders?

A group of zoologists write about this finding in a new paper published in Royal Society Open Science. They analyzed 293 different social species, including reptiles, birds, insects, and mammals, and asked two simple questions about each one: How many females live in each group of these animals; and how many of those females are "breeders," capable of reproduction? Study co-author Eileen Lacey, a biologist at University of California-Berkeley, told Ars by phone that it was surprisingly hard to find this data. "In all the studies of social animals, very few people reported critical information like how many individuals are breeding versus not," she said. Nevertheless, she and her colleagues gathered enough data to perform a statistical analysis of the relationship between number of breeders and female population size.

"The proportion of breeders in societies with more than one reproductive female appeared to be dependent upon the total number of females in the group; when societies with multiple breeding females from all taxa (ants, wasps, mammals, birds) were pooled, we found that the proportion of breeders decreased significantly with the total number of females in the group," the researchers wrote in their paper.