Firstly, a new pied babbler paper by Martha Nelson-Flower. This new study has found that, unlike for females, male-male competition is not costly for the dominant male in pied babbler groups. Pied babblers groups are typically highly kin structured, with only the dominant pair being unrelated and so able to breed. But when a subordinate male is unrelated to the dominant female he is able to compete to breed. However, this new study has found that in these situations do arise there is almost no cost to the dominant male: it doesn’t affect the number of successful nests, the number of fledglings fathered by the dominant or his chances of retaining his position. This is in stark contrast to the cost of female competition in this species. When two females are able to breed it delays the onset of breeding, reduces the number of successful breeding attempts and results in females destroying each other’s eggs. Taken together, these two studies show a drastic difference in intrasexual competition in this species that has a huge impact on the group dynamics and evolution of sociality. It also strengthens the arguments put forward about why female fledglings are so much more aggressive than their brothers!
New paper (male-male competition): Male-male competition is not costly to dominant males in a cooperatively breeding bird. Behavioural Ecology and Sociobiology
Old paper (female-female competition): Costly reproductive competition between females in a monogamous cooperatively breeding bird. Proceedings of the Royal Society London B
Secondly, researchers looking at the morphology of Rocky Mountain bees have found that over the last 40 years their tongues have gotten shorter. They suggest that this is due to the changes in flower distribution and abundance brought on by climate change. Because drier weather is reducing the number of flowers, bees have to work harder to find nectar and so bees with traits best suited to the new environment are favoured. It’s amazing to see evolution in action, in a similar way to Claire Spottiswoode’s work on honey guides.
Bee paper: Functional mismatch in a bumble bee pollination mutualism under climate change. Science
The study’s lead author Nicole Miller-Struttmann suggest the reason for the direction of evolution are that “It would take longer to find the deep flowers, so the longer-tongued bees are going to spend more time searching. But if you’re a generalist, short-tongued bee, you’re more likely to run into your resource.”