Credit:Taod, "Self-portrait in spin"

A brave newt world
by Lauren Bertin

[Article featured in The Bennington Free Press, September 2010]

While all summer long we have experienced the effects of climate change, Stephanie van Ryzin '11 has been analyzing how climate change possibly disturbs the mating habits of the Red-spotted Newt. Under the guidance of Biology faculty member Elizabeth Sherman, Ryzin's findings suggest that male newts seem to have the ability to visually discriminate between females infected by a specific parasite that is endangering their population with females that are not infected.

These small orange spotted amphibians are essential components of the surrounding environments around Bennington. Transmitted through a leech bite, the infection does not seem to directly kill the newts, but rather increases their chances of other more fatal infections and thus could ultimately alter, in this indirect way, the current configuration of the ecosystems where these newts are found.

"With Climate Change, there are a lot of infections that are becoming more prevalent," explains Ryzin, " And mate choice can predict where the population will be in the future, their possible numbers and even existence."

Prior to the observations made this summer by Sherman and Ryzin, many scientists, including Sherman, had implied that climate change was directly connected to a higher frequency of infections found in amphibians. With this concept in mind as well as the idea that species mate with those who can produce the fittest offspring (remember Darwin?) and a vivid passion for conservation, Ryzin began by designing multiple experiments in her mind and on paper. In fact, she actually set up experiments to study visual and olfactory mating cues since both have been in previous experiments shown to affect the mating the patterns of amphibians.

The Red-spotted Newts were collected from two ponds in the local area. Females were separated from males and infected individuals were separated from uninfected individuals. Ryzin explained that the process of sorting the newts consisted of looking for bigger hind legs and large ventricles in the tails to signify that the newts were males, and spotting, swelling and secondary open wounds with fungus growth to identify that the newts were infected.

To test olfactory cues, female newts similar in size and weight were placed in water for over twelve hours, and males were placed on a platform in-between the waters that the females had inhabited. Ryzin counted how often the males avoided the "infected" and "uninfected" waters with many different male and female newts. The objective was to see if a female having the infection could affect the male newts' mating habits; the results, however, did not seem to show that olfactory cues from the females affected male mating habits.

To test visual cues, a tank was designed with translucent border to separate an infected and uninfected female, also of similar size and weight. A male was then placed in front of them both and Ryzin recorded whether the male was more likely to go towards the infected or uninfected female. While she is still calculating her results, she is already able to infer that there is some significant data that reveals that male newts will use visual cues in order to choose the female that is not infected over the one that is.

"It was a great learning experience... [Elizabeth Sherman] gives me a lot of freedom and is very supportive," Ryzin stated. She also noted that she was grateful that Science Technician David Norman, who helped build the designs, also provided a great deal of encouragement.

Ryzin is planning to continue working on this specific research question for the rest of her fall semester. She hopes to find out more about how climate change intensifies this virus, which in turn affects the mating habits of male newts.