Natural selection occurs in real-time
A new paper in Ecology claims to show natural selection occurring in real time, heaping more evidence onto the pile that is evolution (excuse the imagery). The story goes like this: boreal forests in northeastern North America have been cut back and fragmented over the last 100 years. In contrast, temperate forests in the same region, once severely deforested, have reversed the trend and actually undergone afforestation. Thus, travel between the boreal forests became more difficult for birds, and travel between temperate forests became easier. A group from Quebec and Cornell then hypothesized this: birds that lived in the boreal zone would show adaptations over time for more efficient flight, while birds that lived in the temperate forests would show relaxed selection for efficient flight. As a metric of natural selection, the researchers chose the ‘pointiness’ of the bird wings. They argue that pointier wings, which are known to evolve rapidly in birds, are better suited to efficient long-distance flight. Rounder wings, however, consume less energy and are better suited for close-range foraging. Thus, they expected birds in boreal zones to show pointier wings over time, and birds in temperate zones to show the reverse trend.
And that’s exactly what they saw. Taking hundreds of specimens kept at the Canadian Museum of Nature and dating back to 1900, the researchers measured the pointiness of the bird wings. Of 21 species studied, all of them showed the expected trend in wing pointiness. More than half of the birds showed statistically significant changes, which is astounding for a study with just a century-wide window. Though more research needs to be done to prove that the changes were due to inheritance, this paper provides strong support for the primacy of basic evolutionary processes.