The paradox of different house flies with few genetic differences

September 05, 2019

In the steamy, often filthy world of the humble house fly, (the Musca domestica) clear division exists among the males of the species. Though not a civil war, there are differences, to be sure, between males in the north and those that hail from the south. Finding out why those differences appear in the genetic sequences of the northerners and southerners is key to understanding nothing less than sex determination, but there is an essential paradox: The genetic difference is trivial.

"We are seeing a physical difference and that tells us we will see a genetic difference that gives rise to the physical difference, but we find very little genome differences," reports Richard Meisel, UH assistant professor of biology and biochemistry, in the September cover article of Genetics journal. The physical alteration suggests temperature is a meaningful difference between the two types of males.

"We want to know how these things that are so physically different in an evolutionarily meaningful way can have such similar genetics," said Meisel.

The heart of Meisel's work is sex determination. Scientists understand it relatively well in humans - a gene on the Y chromosome initiates the male developmental process, and the process is the same in almost all mammals. But outside the class of mammals, sex determination operates differently. The house fly has substantial variation in how the male/female decision is made. There are two common ways that male development can be initiated, and they differ in their geographical distributions. One male-determining variant predominates at northern latitudes, and the other is more common in the south.

Y is why

Though minute, the difference between the two types of flies is the position of the Y chromosome in the sequence of the genes.

"If Y is the reason then there has to be something genetically about that chromosome that allows it to be that reason," said Meisel. "It's hard for us to wrap our heads around how that trivial amount of difference in the genome sequence causes this variation," said Meisel, adding that evidence indicates natural selection maintains sex determination in the house ?y.

Along with graduate student Jae Hak Son, Meisel examined Y chromosomes by performing mRNA-sequencing experiments to measure gene expression in male house ?ies carrying different Y chromosomes. The exploration allows him to identify candidate phenotype differences between males upon which natural selection can act to maintain the variation in sex determination.

"Our results suggest that, if natural selection maintains polygenic sex determination in house ?y via gene expression differences, the phenotypes under selection likely depend on a small number of genetic targets," he said.
Leo Beukeboom at the University of Groningen in the Netherlands and Daniel Bopp at the University of Zurich are also on Meisel's team.

University of Houston

Related Natural Selection Articles from Brightsurf:

Genetic determinants of fertility and ongoing natural selection in humans
A recent study presented at the ASHG 2020 Virtual Meeting suggests genetic variants may be associated with reproductive success.

Forearm artery reveals humans evolving from changes in natural selection
Humans haven't developed genetic mutations for telepathy or superpowers just yet, but a new study shows our species is still evolving in unique ways and changes in the natural selection could be the major reason.

Novel technology for the selection of single photosynthetic cells
New research, published in the journal Science Advances, demonstrates how microfluidic technologies can be used to identify, isolate and propagate specific single photosynthetically active cells for fundamental industry applications and improved ecosystem understanding.

Genomic selection in dairy cows creates opportunities not possible with traditional selection
The 2019 ADSA Annual Meeting featured the Joint ADSA/Interbull Breeding and Genetics Symposia titled ''Ten Years of Genomic Selection'' and ''Data Pipelines for Implementation of Genomic Evaluation of Novel Traits.'' Because of genomic selection's importance to dairy science, the Journal of Dairy Science invited the speakers to submit articles and share information from these symposia with a wider audience.

Recurrent genomic selection for wheat grain fructans
Development of Climate-Resilient, Nutritionally Improved Wheat

NASA's OSIRIS-REx in the midst of site selection
After a lengthy and challenging process, the team is finally ready to down-select from the four candidate sites to a primary and backup site.

The argument for sexual selection in bacteria
The evolutionary pressure to pass on DNA can produce behavior that otherwise makes no sense in a struggle to survive.

Sexual selection influences the evolution of lamprey pheromones
In 'Intra- and Interspecific Variation in Production of Bile Acids that Act As Sex Pheromones in Lampreys,' published in Physiological and Biochemical Zoology, Tyler J.

Infection biology: Signs of selection in the stomach
Helicobacter pylori, a globally distributed gastric bacterium, is genetically highly adaptable.

Study finds natural selection favors cheaters
Natural selection predicts that mutualisms -- interactions between members of different species that benefit both parties -- should fall apart.

Read More: Natural Selection News and Natural Selection Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to