The story of a butterfly that explains how species evolve.

People often wonder or rather doubt how new species are formed. Some people doubt the whole phenomenon of evolution because it's "a theory of evolution". However, in reality, evolution happens and we can find evidence of it in nature. Here, for instance, a species of butterfly in Amazon region was found to have evolved from the hybridization of two other species of butterflies. Interestingly, the descendants of all these three lineages of butterflies coexist in same geographical region and two of these occasionally mate with each other.

Extinction of large number of vertebrates began in 19th century

We all know that habitat loss due to human interventions have threatened the live of many animals. Data on genetic diversity within a species can be used to quantify their declining population. Recent study published in PNAS suggests that the extiction of large number of vertebrates started in 19th century (123 years ago) which coincided with large scale industrialization. In 2764 threatened species of vertebrates studied by them had their population decreased to ~5% on average. In simple terms, if there were thousand individuals of a species 123 years ago, now only about 50 survive. Every ten years 10% of the population was destroyed by various reasons.

It should be noted that they also compared the genetic diversity data of threatened species with the data of non-threatened species closely related to the ones they considered threatened. It was found that species whose population was small were more vulnerable to extinction. Now to generelize for future, predators or endemic species have small population in general. As humans occupy and modify more habitats more of such species are going to be affected. In coming decades, we are going to see a lot of them get vanished.

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