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Professor awarded over $1 million to study all-female unisexual salamanders found in Indiana

Found in Indiana: A Million Dollar Salamander
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Posted at 1:16 PM, Oct 29, 2021

INDIANAPOLIS — A Marian University professor has been awarded $1.1 million to study an unbelievable group of all-female salamanders that "steal" sperm from males of other species.

Understanding the unisexual salamander could change the way humans view reproduction and fertility.

"If you're walking around the woods in Indiana or throughout the Midwest, you're likely walking over these animals that are under the ground and hibernating," Dr. Rob Denton, an evolutionary biologist and biology professor at Marian University, told WRTV about salamanders.

Indiana and Ohio are the epicenters for the unusual group of all-female mole salamanders. These salamanders break all of the rules scientists know to be true about reproduction.

"There are no males," Denton explained. "They reproduce in a completely unique way for animals where they can steal reproductive material from males of other species. So they're kind of sexually reproducing, kind of asexually reproducing."

The all-female mole salamander is attracted to the Midwest because the five male salamander species they predominantly take sperm from reside here.

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A female mole salamander.

Denton explains that it starts with the basic understanding of how salamanders broadly reproduce. Come spring, males go into wetlands and lay down packets of sperm on the floor of a body of water. Then, depending on the species, the males try to court female salamanders of their species, to get them to pick up their sperm. Some males don't and just hope for the best, Denton adds.

"This all-female group, we don't exactly know the details of how they do this. But we know they do pick up those sperm packets from another species. And what usually happens is that initiates her egg development, she lays eggs, and all of those offspring are clones of mom," Denton said.

Being able to asexually reproduce only female offspring by themselves is not the only unique phenomenon scientists are seeking to understand about this group. Denton says not only do they have the ability to regenerate, but the genome of the all-female mole salamanders is an evolutionary divergence.

"Sometimes that genetic information from the male sneaks into the next generation and just adds on to what [the all-female mole salamander] already have," the evolutionary biologist explained. "And so that analogy that we often use is ... if you took a sequence of my DNA, or sample of my DNA, and I had a set of chromosomes from my mother, set from my father, but then I also had a set from an orangutan, a chimpanzee, a gorilla, and I was just a normal functioning human being.

You may be wondering by now — does the all-female mole salamanders have a name? Well, Dr. Denton explains, naming these salamanders can't technically be done because not only don't scientists have a term that fits, but these salamanders are not considered their own species.

"A lot of times, they're referred to as either 'unisexual ambystoma salamanders' or 'all-female mole salamanders,' something like that. But we can't give a species name to something that doesn't play by the species rules that we humans kind of put around things," Denton said.

The Million Dollar Salamander

Although Professor Denton has been studying the all-female mole salamanders since grad school, he says there is still so much to understand about the salamanders' bizarre genetics.

"[We want] to try to understand how they get away with this situation that would be so fatal to all other vertebrates," Denton explained.

The National Science Foundation's $1.1 million career grant is funding that research in a particular way.

The grant provides five years of funding to a pre-tenured professor who will combine both research and teaching.

Dr. Denton plans to hire multiple Marian undergraduate students as research assistants to help with research and the collection of specimens. He will also be partnering with other Midwest-based scientists.

"They have a lot to teach us besides just being inherently interesting organisms that are out in the real world," Dr. Denton said. "But humans are interested in them for some very specific reasons as well."

According to Dr. Denton, the all-female unisexual salamander also has the ability to regenerate. In a 2016 article for Discover Magazine that Dr. Denton was interviewed for, journalist Elizabeth Preston explained that when these salamanders "lose an appendage, they can grow it back much more quickly than other salamanders do." Because of this, biomedical scientists are interested in understanding how humans can regenerate human tissue after injury.

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Marian University professor Dr. Rob Denton.

"The crux of the science in this grant is looking at the relationship between that part of their genome that they inherit only from mom, and then the part of their genomes that are switching in and out across generations. In humans, and many other vertebrates, the coordination between those two is really important to basic parts of you being alive," Dr. Denton said.

Denton hopes to eventually understand how the unisexual all-female mole salamanders pull off "this really predicted amount of conflict" between genomes through the research. Furthermore: How does that relate to their metabolic rates? How does that relate to their evolution?

He also wants to dictate whether they're stealing or not stealing from males of other species. Finally, to understand how they get away — and thrive in — a situation that would be so fatal to all other vertebrates.

Over the next five years, Denton gets to try and figure this all out alongside his students. He says it's his favorite part of the grant.

"Smaller universities, oftentimes, are really good candidates for these because we have the most direct line to students to actually take the research we do and move it into the classroom and work, in that way," he said. "Because that's something I've always valued, you know, this is really the grant that I was most excited to apply for because it was kind of the truest sense of what I like about my job."

Dr. Jonathan Lowery, Marian University's assistant provost for research and scholarship, says he believes all of the faculty at the university are poised to couple "innovative education practices" with advanced real-world research.

"Dr. Denton's recruitment and his prestigious funding from the National Science Foundation are landmark events in the growth of research and scholarship at our institution," Dr. Lowery stated.

"Marion is a really interesting place. For a lot of small universities, they are really struggling right now. And Marian, by most metrics, is doing really well. It's growing in terms of the number of students, in terms of endowment, their investment in research and scholarship here. And so it's fun to be at a university that values both teaching, and research," Denton said.

WRTV plans to keep up with Dr. Denton's research and will provide an update when the time comes.

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WRTV Digital Reporter Shakkira Harris can be reached at shakkira.harris@wrtv.com. You can follow her on Twitter, @shakkirasays.