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Hormone-mimicking chemicals cause inter-species mating, University of Minnesota researcher finds

July 11, 2012

Hormone-mimicking chemicals released into rivers have been found to affect the mating choices of fish, a new study led by a University of Minnesota scientist has found. The controversial chemical BPA, which emits estrogen-like properties, was found to alter an individual’s appearance and behavior, leading to inter-species breeding. The study, published in Evolutionary Applications, reveals the threat to biodiversity when the boundaries between species are blurred.

The research, led by Jessica Ward from the University of Minnesota, focused on the impact of Bisphenol A (BPA) on Blacktail Shiner (Cyprinella venusta) and Red Shiner (Cyprinella lutrensis) fish which are found in rivers across the United States. BPA is an organic compound used in the manufacture of polycarbonate and other plastics. It is currently banned from baby bottles and children's cups in 11 U.S. states.

“Chemicals from household products and pharmaceuticals frequently end up in rivers and BPA is known to be present in aquatic ecosystems across the United States,” said Ward. “Until now studies have primarily focused on the impact to individual fish, but our study demonstrates the impact of BPA on a population level.”

The team collected individuals of both species from two streams in Georgia. The species were kept separated for 14 days in tanks, some of which contained BPA. On the 15th day, behavioral trials were undertaken as individuals from different tanks were introduced to each other.

The scientists monitored any physiological or signaling differences the individuals displayed, such as color, as well as any behavioral differences during courtship, such as mate choice.

BPA disrupts an individual’s endocrine system, which controls the release of hormones. This affects behavior and appearance, which in turn can lead an individual to mistake a newly introduced species as a potential mate.

This process poses long-term ecological consequences, especially in areas threatened by the introduction of invasive species. BPA and other hormone-mimicking chemicals can escalate the loss of native biodiversity by breaking down species barriers and promoting the invader.

“Our research shows how the presence of these manmade chemicals leads to a greater likelihood of hybridization between species,” Ward saod. “This can have severe ecological and evolutionary consequences, including the potential for the decline of our native species.”

Media note: Upon publication the paper will be available at: http://doi.wiley.com/10.1111/j.1752-4571.2012.00283.x

About the Journal:


Evolutionary Applications is a fully peer reviewed open access journal. It publishes papers that utilize concepts from evolutionary biology to address biological questions of health, social and economic relevance. Papers are expected to employ evolutionary concepts or methods to make contributions to areas such as (but not limited to): agriculture, aquaculture, biomedicine, biotechnology, climate change, conservation biology, disease biology, fisheries and wildlife management, forestry, invasion biology and toxicology. Theoretical, empirical, synthesis or perspective papers are welcome.

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