Jack Billings
http://www.futurity.org/science-technology/sex-life-of-plants-can-alter-their-defenses/
Published: February 25, 2013
Source: futurity.org
Author: Krishna Ramanujan
Summary:
Recent studies have shown that the evolution of a plant’s defense system is tied to the method the plant uses to mate. Some plants self-fertilize or mate with relatives (inbreeders) while others mate with non-relatives (outcrossers). Researchers have found that these two types of mating styles have caused very different defense strategies to evolve. Inbreeders’ defense systems do not become activated until after their leaves have been eaten or damaged. The defense systems of outcrossing species however, are always turned on. One reason for a defense system that only activates when needed could be that inbreeders often colonize new areas where they have little to no predators and, therefore, do not need the defense. The reason inbreeders have an advantage for colonizing new areas is that they do not require a large population to reproduce because they can self-fertilize or breed with their relatives. The inbreeders that had their defense systems turned on all the time were wasting energy and were therefore outcompeted (through natural selection) by those who only turned their defenses on when necessary. On the other hand, outcrossers colonizing new areas is much more rare, (because of their need for a large population to reproduce) so they constantly need to defend against herbivores and parasites that could hurt them. Because of this, they have developed defense systems that are on at all times.
Connection:
This connects to our study of plants and evolution because it discusses how one aspect of a plant may have affected the evolution of another. More specifically, it connects to the different methods of reproduction, and the different defense systems. It explains that the methods of reproduction of different plants have (over time) determined the way the plants defend themselves, and it discusses how these defense systems are adaptations.
What is an example of an inbreeding plant and an outcrossing plant and what defense mechanisms would these plants use?
ReplyDeleteAn example of an inbreeding plant is a tomato plant. It releases toxic chemicals when provoked by caterpillars. This chemical is poisonous to the caterpillars, but also attracts wasps (which help kill the caterpillars). An example of an outcrossing plant is squash. It produces tiny thorns all along its stems and the undersides of its leaves to keep away small predators and discourage larger ones. It also gives off a smell that repels some predators (like deer).
DeleteDon't some inbreeding plants have natural predators, though? If they do, then wouldn't it be advantageous for them to keep their defense system on?
ReplyDeleteYes, this is just a generalization, but even if an inbreeding plant has natural predators in one area, it may not if it moves to a different area (which is easier to do for inbreeding plants than outcrossing ones). If it moves to new areas frequently enough, there would rarely be a need for the defense system, so keeping it off when it isn't necessary would save energy.
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