Roads Are Driving Rapid Evolutionary Change in Our Environment

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Roads Are Driving Rapid Evolutionary Change in Our Environment

Roads are causing rapid evolutionary change in wild populations of plants and animals according to a Concepts and Questions paper published in  Frontiers in Ecology and the Environment. 

The paper is available now online in ‘early view’ ahead of being featured on the cover in the print edition on March 1. (A pdf of the paper is also available here).

Said to be the largest human artifact on the planet, roads impact the ecology of nearly 20 percent of the U.S. landscape alone, and globally, are projected to increase 60 percent in length by 2050; yet, how roads are triggering contemporary evolutionary changes among plants and animals, is a topic that has typically been overlooked.

By drawing on previous studies, the researchers show that the numerous negative effects of roads – such as pollution and road kill – can cause rapid evolutionary changes in road-adjacent populations. This finding that roads spur rapid evolution is transforming scientists’ views of the biological impacts caused by the ever-expanding network of roads.

Over a period of just a few generations – and in one case in as few as just 30 years – some populations living in road-adjacent habitat are evolving higher tolerance to pollutants, such as road salt runoff; the common grass   (Anthoxanthum odoratum)  is one such example, the spotted salamander ( Ambystoma maculatum ) is another.

Despite this positive influence of rapid evolution, road-adjacent populations are not always able to adapt to life beside the road, at times becoming ‘maladapted,’ evolving lower tolerances to negative road effects. 

This can occur even if other species in those habitats are adapting, as was the case with the spotted salamander and a cohabitant frog. Earlier fieldwork by Brady found that the survival rate for wood frog ( Rana sylvatica ) populations living by the road was 29 percent lower than those transplanted from other areas. 

With the spotted salamander and wood frog, the fitness of each population had increased and decreased, respectively, relative to populations not living roadside, which demonstrates how local adaptive and maladaptive changes are occurring through natural selection among various species. Even though a population may experience local adaptation, the researchers point out that while evolution might decrease the chance of local extinction, it does not preclude it.

Read more at: Dartmouth

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