It is obvious that pollution has caused artificial changes in the environment. Pollution is causing dramatic changes in Evolution and Ecology. Sewage treatment facilities are an example of how artificial ecosystems develop. Many microorganisms and small insects live in the filter beds of sewage treatments. These organisms are obtaining natural estrogen through human waste and estrogenlike compounds from plastics that build up at filter beds. Exposure to natural and synthetic endocrine disrupting chemicals (EDCs) alters changes in the endocrine systems. According to an article in The New York Times “The chemicals are known to disrupt endocrine function, with anatomical and behavioral effects.”
Shai Markman and Katherine L. Buchanan have researched the European starling (Sturnus vulgaris) in Britain. They have a fully written research article on what they observed. The researchers noticed that the starling mainly feed on worms living in these filter beds. The researchers observed that the birds are highly affected by estrogen (a hormone), dioctylphthalate (toxin), bisphenol A (an organic compound that mimics estrogen), and dibutylphthalate (a toxic air pollutant). The researches captured starling, and in a lab, gave them similar amounts of estrogen and toxins through mealworms introduced with high levels of these toxin and estrogen based compounds. In result, the researchers observed that the starlings’ songs’ became more complex because the part of the brain that produces their song became overdeveloped. The complexity of the male birds’ song attracted more females due to sexual selection. Females favored the male birds with high levels of estrogen over birds that were in a control condition. It may seem as if it is beneficial for mating. However, the starling’s immune system becomes very weak due to the exposure of toxins consumed from the worms. The starling’s reproduction system along with many other internal systems became disrupted and in some cases reproduction systems did not function properly. The researchers predict that the females will continue to mate with the males with poor immune fitness and eventually natural selection will wipe out starling with healthy immune systems. It may be too early to tell but the effects of the artificial ecosystem may cause starling to produce offspring with weaker immune systems thus, decreasing the chances of survival.
Posted by: Carlos A. Varela
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Wow. It sounds like this could wipe out this species, if the females are choosing males with higher estrogen levels who's immune systems and reproductive systems have been affected. Has any research been done to find a way to prevent this from happening?
ReplyDelete-Posted by Sarah Benjamin
This article is alarming. However if the birds that have more complex songs due to higher estrogen levels have worse reproductive systems wouldn't birds with simpler songs and better reproductive systems out compete the complex song birds through having viable offspring. How many males do females mate with? If they mate with many the simple song bird will be more fertile and be able to produce more offspring. Hopefully this is the case and we are not seeing the end of a species.
ReplyDeletePosted by Tiffany Mallet