Scientists have discovered a genetic mechanism that can determine the sex of the squinting bush brown butterfly or Bicyclus anynana. Intriguingly, their investigation led to an additional discovery.
When individuals carrying identical variants of a sex-defining gene mate, the resulting embryos cannot survive. This is the first time that this mechanism has been described in butterflies. This mechanism is also similar to one described in honey bees.
Because it reproduces quickly and easily, the squinting bush brown butterfly is often used for genetic research. Additionally, the butterfly’s entire genome has been sequenced, which is beneficial for research.
Having the complete genome sequence allows scientists to study Bicyclus anynana in greater detail. For example, scientists can identify specific genes associated with different traits.
X and Z, W and Z, Masculinator
Unlike mammals with X and Y chromosomes, butterflies and moths (Lepidoptera) have W and Z chromosomes. Females usually have a W and Z chromosome, while males have two Z chromosomes.
However, there are some female butterfly species that do not have a W chromosome. This process is regulated by combinations of gene variants called “masculinizer genes”; one variant leads to female development.
On the other hand, a combination of two different masculinizer genes leads to male development. Embryos fail to develop when two identical variants of this masculinizer gene are inherited.
However, this is rare in natural populations where diverse gene variants are present. The likelihood of inheriting two identical variants increases in populations with decreased genetic diversity.
“We report the discovery of a primary sex determination mechanism in the Afrotropical butterfly Bicyclus anynana that differs fundamentally from the mechanism found in B. mori,” stated the research.
“This is unexpected because both species share the common WZ/ZZ sex chromosome system of Lepidoptera,” it added.
“Our discovery of this primary switch highlights the fascinating diversity of sex-determining mechanisms and underlying evolutionary drivers,” it noted further.
Adaptation and protection
For scientists, its similarity to the mechanism observed in honey bees is intriguing. As a member of a special insect group, the butterfly displays a more pronounced similarity to honeybees than to silkworms, despite all belonging to the same insect order.
This is an example of convergent evolution, where unrelated organisms independently develop similar traits for adaptation.
Insights into the genetic mechanisms of species, such as Bicyclus anynana, can aid conservation efforts. This understanding is especially important for species facing challenges such as habitat loss due to climate change. That’s why understanding the process of reproduction can help preserve biodiversity.
Interestingly, these small squinting bush brown butterflies have several spots on its wings, which may direct predator attacks to different locations. These spots, resembling eyes, can distract predators, protecting the butterfly’s vital organs. Additionally, these spots may serve as sexual signals to potential mates.
According to the data, this butterfly can live up to six months in the wild and reaches sexual maturity in about 2 weeks.
Butterflies play a crucial role in nature as pollinators, helping plants, including those producing fruits and flowers, create new seeds.
