WMU biologist helps settle 50-year-old fish evolution debate

KALAMAZOO, Mich.—Growing up surrounded by fish tanks and nearby creeks, Dr. Andrew Thompson's passion for aquatic life ignited at an early age. His curiosity led him to spend time learning about different fish species, which eventually paved the way for his career in fish genome research.

Today, as an assistant professor in Western Michigan University’s Department of Biological Sciences, Thompson's passion led him to co-author a paper titled “Genome structures resolve the early diversification of teleost fishes,” recently published in the esteemed journal, Science. 

“It was a relief and exciting to see when it was finally accepted,” says Thompson. “It's always a goal to publish in these high-impact journals because they have a lot of readership, so your science is seen by a lot of people from all over the world.”

The study sheds new light on a long-standing debate regarding the early evolution of teleost (or “ray-finned”) fishes. Thompson’s research confirmed that eels and bony-tongues were the first evolutionary split in teleosts.

“For years, (researchers) have looked at the DNA sequences, the shape of the animals' bodies and done all these analyses,” says Thompson. “They just keep getting different answers depending on how you look at it.” 

Thompson sought to finally “nail down” the answer about the early evolution of teleost fishes through genome sequencing. Early classifications suggested that the "bony-tongues" were the oldest group, while more recent classifications identified "eels" as the oldest.

“When we infer these evolutionary histories, it’s impossible to know you have the right answer because you can’t go back in time and see what evolution did,” says Thompson. “We can infer them using genetic data.”

To finally settle the 50-year debate, the research team sequenced the genomes of several species in the "eel" group, revealing that the "eels" and "bony-tongues" are actually one and the same group, which researchers named "Eloposteoglossocephala." This finding will provide the basis for further studies on the evolution of teleost fishes.

With the age-old teleost debate settled, Thompson is now seeking to understand killifish dormancy. These organisms, which possess embryos that can withstand seasonal dryness, provide unique insight into evolution, development, behavior, cancer and aging. Thompson’s lab uses them as a model to study the evolution of different traits in harsh environments. 

From a childhood hobby in Western Pennsylvania to a professional pursuit of knowledge, Thompson's interest in fish evolution has only grown. He aims to inspire others to find and follow their own passions.

“Use whatever curiosity you have, and your passion for some weird nerdy thing and start early to pursue that,” says Thompson. “It’s never too early to start.” 

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