Sewanee Research Professor Thea Edwards has published a review article in the journal Evolutionary Applications. The article is a fruitful collaboration between Dr. Edwards and Max Lambert, her colleague at Yale University. The article reviews current knowledge about plant chemicals that affect animal hormone systems.
In an interview, Dr. Edwards commented on this exciting area of research. "We are learning that plant chemicals can manipulate reproduction and behavior in vertebrate animals, like frogs and mammals. For a long time, these effects have been viewed as a form of toxic plant defense - that is, that plants make these chemicals to stop reproduction of the animals that eat them. But, new evidence suggests that the story is much more interesting."
Poor reproduction is not always a bad thing. Consider an animal that reproduces when environmental conditions are harsh, when there is no food for example. The offspring will not survive, and the parents might jeopardize their own survival with the added burden of feeding young.
Under these stressful conditions, many plants make high amounts of chemicals called "hormonally active phytochemicals" or "HAPs." When animals eat the plants, the HAPs alter the animals' reproductive function, and they do not breed. But, when environmental conditions improve, plants produce fewer HAPs. This decrease releases animals to breed when conditions are good. In this remarkable way, animals and plants may cooperate to ensure survival of both.
It's important to note that production of HAPs is highly variable across plant species. Animal sensitivity to HAPs also depends on many factors, including species, age, reproductive status, and amount of HAPs in the diet.
There is some evidence that humans can be affected by HAPs. Consider the many popular publications on phytoestrogens in soy products.
To learn more about this innovative research area and the article by Lambert and Edwards, please click on the following link: http://onlinelibrary.wiley.com/doi/10.1111/eva.12469/abstract