Clues to How Plants Evolved to Cope With Cold

Date of Publication: December 22, 2013
Link: http://www.sciencedaily.com/releases/2013/12/131222161805.htm

Summary: Researchers have recently discovered how plants evolved to cope with cold weather. By studying fossil evidence and reconstructing the past climate conditions, researchers were able to suggest that early flowering plants first began to grow in a climate that was warm and tropical. Then researchers identified three traits plants have to avoid freezing in the cold: dropping their leaves before the cold weather can freeze them, having narrower water transport cells and a finer circulatory system, and dying back into the ground and re-sprouting from the roots in the spring. Once researchers were able to compile all their leaf and stem data, they mapped it out on the evolutionary tree for flowering plants. By doing this, researchers were able to see that many plants had these cold weather traits before they were even in colder climates. It is hypothesized that these were adaptations developed due to droughts, with the only difference being that these traits did not begin happening right before winter until plants began encountering freezing weather.

Relevance: This article relates to the evolution unit, and how organisms through natural selection are able to adapt to new climatic conditions. Before flowering plants were introduced to the freezing temperature of winter, they had to adapt to droughts. Through natural selection plants with the ability to drop their leaves and regrow them, or plants that had a finer circulatory system, or plants that had the ability to die and regrow again were best suited to these drought conditions. So because these plants were better suited to their environment, they were able to live longer and pass these traits on to more offspring than plants without these traits. As plants were able to slowly spread to higher latitudes, these traits began to be useful. But again natural selection came into play, so plants that were able to drop their leaves earlier and earlier before winter were able to survive better than plants that would drop their leaves to late. So through natural selection, plants in higher latitudes have traits that allow them to survive through the winter. This article is an example of how natural selection can help populations of organisms evolve.