Aggressive bonobos, bacteria to fight dengue, & hybrid butterflies | Last Week in Science (21 March 2024)

The upside of being aggressive

Chimpanzees are known to be more aggressive than bonobos and also humans. A recent study has challenged this view, finding bonobos to be more aggressive than chimps.

They observed these great apes behaviour from the moment they woke up to when they returned back to their nests. The findings were startling. Bonobos were 2 times more likely to engage in aggressive behaviour than chimps. While chimps are known to even show aggression towards females, in bonobos, it was restricted to male-male aggression. The scientists explained that chimps are known to form groups, and higher level of aggression can affect the group dynamics. This unrest within a group can compromise their ability to defend the group. On the other hand, bonobos do not engage in inter-group politics and are thought of as being more individualistic. Unlike the well planned killings by chimps, the aggression of bonobos is thought of as more passive i.e., not planned and rarely leading to the killing of another male.

Unlike chimps, where males are more dominant, female bonobos are known to share an equal footing in the bonobo community. It was interesting to see that both chimps and bonobos that were more aggressive had a better chance of finding a mate.

Reference: 
Bonobos are more aggressive than previously thought, study shows
Differences in expression of male aggression between wild bonobos and chimpanzees

Fighting Zika and dengue with gut bacteria of mosquitoes

Dengue and Zika are viral diseases that are transmitted through mosquitoes to humans. One way to prevent the disease is to stop these viruses from infecting and growing inside mosquitoes. Researchers in China have found a method to do just that by investigating the bacteria that are present inside the gut of mosquitoes that carry dengue and zika virus.

It started from catching the mosquitoes that cause dengue and then identifying the different bacteria that live inside the mosquito. The researchers then gave antibiotics to the mosquitoes and introduced the different bacteria one by one along with dengue virus. When a species of Rosenbergiella bacteria was introduced, the mosquitoes did not get infected by dengue. This bacteria made the gut of mosquito acidic which did not let the dengue virus to grow. Next, the researchers made Rosenbergiella carrying mosquitoes to bite mice that had dengue virus, and the mosquitoes did not let the virus grow inside their body.

It was interesting to find out that in the regions where dengue and zika cases are low, the mosquitoes that cause dengue carry Rosenbergiella, whereas mosquitoes in regions with high cases do not have this bacterium. The researchers are now going to test whether the mosquitoes with Rosenbergiella can reduce the cases of dengue infection in regions where the cases are high.

Reference: Bacteria found in mosquito guts could help scientists fight dengue, Zika

Hybrid butterflies that became a new species

In the last episode, we saw how ozone can confuse fruit flies into mating with a fly of a different species producing baby flies that were infertile. It is well known that in most cases, when different closely related species mate, the result is an offspring that is infertile, which cannot reproduce, or a gradual merging of two species into one. However, a beautiful creature exists that defies this existing knowledge. A recently published study in Nature reports the existence of a species of butterfly in the Amazon whose parents are two independent species that still exist.

A red, black, and yellow colored butterfly of the Amazon - Heliconius elevatus looks identical to a butterfly species H. melpomene because of its colors but is genetically similar to another species H. pardalinus. The researchers wanted to understand whether H. elevatus shares genes with these two other species.

The scientists studied the genes of all three species. They found that the the hybrid species shared 99% of its genes with one and just 1% with the other species. The color, wing pattern, choice of plant for feeding, pheromones and mate choice of H. elevatus come from this 1% of the genes coming from one of the parents. And it is this 1% difference in H. elevatus that keeps it as a distinct species by ensuring that breeding occurs amongst its species and not with the parental species, which has been so since 180,000 years.

Reference: Striking Amazonian butterfly is result of ancient hybrid event

Edited by Ashish Gourav