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Goby Fish Size Study

A new study unravels the genetics behind why some fish remain tiny.

Imagine you are a kind of fish called a goby,part of a huge family of more than 2,000 species.

Maybe you’re of average size for a goby, about three to four inches long. Your ⁢longest relative is about ⁢four times your length-more than a foot⁤ long.Your smallest relative is similarly about four times smaller than ⁤you, clocking in at⁣ under an inch.

In⁣ human terms, that’s like having one cousin who’s 22 feet tall and another cousin who’s just over a foot ⁣tall.

University of⁤ Michigan⁢ postdoctoral researcher Emily Troyer ⁢led⁢ work investigating why gobies‍ exhibit such a size ⁣range, focusing in particular on how gobies are able to ⁢regulate size in order to stay miniature.

She found that certain gobies overexpress two genes that inhibit growth, keeping some species of goby⁢ miniaturized.

Additionally, by looking⁤ at ⁢different groups of gobies across ⁢time, she found that miniature gobies have used the same genetic pathways to regulate thier size since the Eocene, more than 50 million years ago.

The work, supported by the US National Science ⁢foundation, appears in‍ the Proceedings of the‍ National Academy of Science.

“Body size is probably⁣ the most critical organismal trait. It’s linked to so many biological processes,from metabolism to reproduction,” Troyer says.

“So by⁣ understanding the controls over body size, this ‍not only has implications for evolutionary biologists, but⁤ maybe also biomedical scientists⁤ who want to understand the growth of tumors.”

Troyer⁢ says the underlying ⁢genetics of body size has remained a question for scientists. Understanding how organisms control their body size is ⁢critically‍ important as size determines many other components of an organism’s ⁣existence, such as where it lives, what it eats, the shape of its body, and how‍ it reproduces.

“We understand a little bit about the why. So if you’re small, you might be ⁣able⁣ to⁤ fit into these tiny microhabitats and live ⁢there. Some of these gobies are so small, ⁢they spend the ⁣entirety ⁤of their lives⁣ within‍ a single head of coral, with ⁤a two-square-meter range,” Troyer says.

“What’s a little⁢ less understood is the genetics of why this is happening. We wanted to‍ take⁤ a stab at‍ this question using gobies as our model ⁤system.”

In particular, the genes that Troyer identified in miniature gobies, CDKN1B and ING2, are both associated with regulating and limiting the⁤ number of ‍cells grown in the goby.

To determine which ⁤genes were most associated with body size, Troyer created a phylogeny, or family tree of 162 goby species.

Key Findings