Microevolution: Pygmies, butterflies, and Tibetans

Three articles about microevolution. That is, the rapid spread of a change in genes through a population because that change confers an advantage to those having the gene.

Article: Pygmy phenotype developed many times, adaptive to rainforest

The small body size associated with the pygmy phenotype is probably a selective adaptation for rainforest hunter-gatherers, according to an international team of researchers. But all African pygmy phenotypes do not have the same genetic underpinning, suggesting a more recent adaptation than previously thought.

Genetic mutations occur in populations all the time. If they have a negative impact on the individual, they tend to disappear from the population quickly. If they have no noticeable impact for the good or bad, they might disappear as well, although more slowly. Mutations which have positive influence on individuals, making them more fit for their environment, tend to spread through the population.

Article: Butterflies' evolutionary responses to warmer temperatures may compromise their ability to adapt to future climate change

Members of the brown argus butterfly species that moved north in response to recent climate change have evolved a narrower diet dependent on wild Geranium plants, researchers report. However, butterflies that did not move north have more diverse diets, including plants such as Rockrose that are abundant in southern parts of the UK.

Article: 8,000-year-old mutation key to human life at high altitudes: Study identifies genetic basis for Tibetan adaptation

In an environment where others struggle to survive, Tibetans thrive in the thin air of the Tibetan Plateau, with an average elevation of 14,800 feet. A new study is the first to find a genetic cause for the adaptation and demonstrate how it contributes to the Tibetans’ ability to live in low oxygen conditions.

About 8,000 years ago, the gene EGLN1 changed by a single DNA base pair. Today, a relatively short time later on the scale of human history, 88% of Tibetans have the genetic variation, and it is virtually absent from closely related lowland Asians. The findings indicate the genetic variation endows its carriers with an advantage.