LSUS herpetologist part of groundbreaking research published in renowned journal

LSUS herpetologist part of groundbreaking research published in renowned journal

SHREVEPORT - An LSU Shreveport herpetologist is part of ground-breaking research in the gecko world.

Dr. Stuart Nielsen, assistant professor of biology, was part of a team that established nearly 20 new genomes for geckos, publishing the research in the journal "Science."

A genome is an organism's complete set of genetic instructions, made up of all the DNA stored in its cells.

"We published new genomes for geckos spanning essentially the gecko tree of life," Nielsen said. "So whereas there were just a handful of gecko genomes before, now we have somewhere between 25-30 of what we call chromosome-level genomes.

"This is a really, really powerful resource for people to do all kinds of studies."

The journal "Science" is one of the most revered peer-reviewed journals with an acceptance rate of 5.3%. Many other peer-reviewed journals have a 20-40% acceptance rate.

Determination of sex in mammals (males give an X or Y chromosome to offspring) and birds (females give the determining chromosome) is standard across species.

But reptiles include both of these systems plus a temperature-dependent sex determination system in which external temperature can be the deciding factor for the sex of offspring.

Geckos are unique among reptiles in that they transitioned between sex-determination systems.

But this research suggests that geckos transition between systems in a particular way instead of randomly, determined by a combination of genetic and environmental factors.

"We know a lot about mammal sex chromosomes and bird sex chromosomes, but reptiles are this third lineage that we don't know a lot about," Nielsen said. "From our research, essentially every time we look at a new gecko species, we get a different sex-determining region of the genome.

"Reptiles, specifically geckos, will eject a (sex determination) system and get a new one. All these things happen that theory says shouldn't happen."

Nielsen's role in the research was to collect numerous species of gecko samples.

Over the last 10 years, he's collected geckos from Hawaii, Puerto Rico, Honduras and Australia, the last of which contained the bulk of the gecko samples used in this research.

Nielsen's postdoctoral advisor Dr. Tony Gamble, an expert in evolutionary biology at Marquette University, connected with the Beijing Genome Institute and eventual lead author of the study Dr. Yang Zhou.

Nielsen added that because of the extreme diversity of geckos, hints to larger evolutionary questions such as why certain traits evolve and how are they expressed in organisms could have more clarity.

"This research really provides a resource and an amazing data set that we've never had before," Nielsen said. "Here's this amazing group of creatures, and what are some of the questions we can now ask with this resource?"