200-year-old DNA Helps Map Tiny Fly's Genetic Course to New lands, Modern Times

 

Researchers from the University of Wisconsin-Madison and Lund University analyzed DNA from fruit fly specimens collected in Europe between the early 19th century and the 1930s. Surprisingly, flies from the early 1800s were more genetically similar to contemporary flies than those from the 1930s, revealing patterns of migration and genetic drift. The study uncovered genes showing signs of evolutionary pressure, aiding in the adaptation to different environments and challenges. Notably, a gene called Cyp6g1 emerged in the 1930s specimens, making flies resistant to the pesticide DDT introduced in the 1940s. Another gene, Ahcy, helped 19th-century flies adapt to cooler temperatures and shorter days. Furthermore, the ChKov1 gene, previously linked to insecticide resistance, was found to offer viral resistance, altering prior understandings.

I find it so interesting that analyzing the DNA of fruit flies from centuries-old specimens, as highlighted in this research article, holds so much significance in the field of genetics. Research on fruit flies is critical because it also provides valuable insights into genetic mechanisms across various species, including humans. As noted in the second article, the fruit fly is a critical model organism in both basic and medical research, with a rapid reproductive rate and deep genetic similarities to mammals. Studies over the decades have revealed that its genetic mechanisms, like the Pax6 gene responsible for eye formation, are conserved across species and its mutations can cause various eye disorders. Overall, research on fruit flies has provided scientists with valuable insights into human gene functions, birth defects, and even complex conditions like alcoholism and drug addiction.

Links: 

https://www.sciencedaily.com/releases/2023/10/231012161830.htm

https://www.upstate.edu/cvr/investigators/francesca-pignoni-phd/why-the-fly.php#:~:text=The%20fruit%20fly%C2%B7is%20a,control%20organ%20development%20in%20vertebrates.

Genetic Differences in Digestion Between Andean Populations

This study inspected the ancient genomes extracted from the Peruvian highlands with comparison more modern genomes from identical regions, that being highland and low-land regions, to identify genomic characterisitcs prevalent prior to the arrival of Europeans. The two regions have distinct environments making it suitable for study of how selective pressures can provoke adjustments in genomes, but is not limited to difference in altitude and agricultural practices. The lowlands were also more suspectable to the introduction of smallpox with the arrival of the Spanish as compared to the more remote Andean highlands.

The gene, MGAM, plays a role in the digestion of starch and has shown to demonstrate variants in the ancient genome that align with the start of potato domestication. A different configuration of MGAM was identified among the high-altitude population as compared to hunter-gatherer populations. The study potentially identified a variant of the DST gene. This gene modification is suggested to be correlated to enlarged right ventricles in individuals living in the highlands. This finding is in line with the suggestion of adaptation to high altitude among Andeans. 

It was found that the results differ from genomic changes among European populations as it relates to dietary changes, but with the rise in grain production in European regions. This was the increase in the amylase encoding gene, which serves as a starch digestive enzyme in saliva. Understand these differences in digestion could improving the treatment of diet related illness by acknowledging genetic differences among populations, such as their ability to digestion starchy foods, and which treatment would be ideal.

European diseases left genetic mark on Native Americans

Earliest encounters between Europeans and Native Americans in the 15th century wiped out a large portion of the native population simply via introduction to old world diseases. A new study suggests that infectious diseases brought by Europeans, such as smallpox and measles, have molded the immune systems of native descendants.

A team led by Ripan Malhi, an anthropologist at the University of Illinois, examined DNA from the skeletal remains of 25 individuals who lived in the Rupert Harbor region of British Columbia between 500 and 6000 years ago. These were seafaring tribes, ancestors of the modern Tsimshian, who first encountered Europeans in the early 1700's.

Researches used whole exome sequencing to sift through genes related to immune response. The team discovered several immune related gene variants which were rare among modern populations. A variant of the gene HLA-DQA1, for instance, codes for proteins that sort healthy cells from invading viruses and bacteria, was found in nearly 100% of ancient individuals, but in only 36% of modern ones. These findings, suggest that ancient Tsimshian were well adapted to local diseases but not to novel infections like small pox and measles. Survivors were less likely to carry variants like HLA-DQA1, which are less capable of coping with European diseases.

Malhi and his colleagues calculated a rough date for the genetic shift, about 175 years ago. Based on new findings and historical records, the team says that 80% of the native tribes in the Prince Rupert harbor region died simply via disease.

I find this study and subject as a whole particularly fascinating, as the role of disease in shaping history and shaping populations into what they are today cannot be understated. The 80% mortality rate amongst the natives of the Prince Rupert harbor region is in no way unique. A little known fact of history is that the majority of native Americans died from introduction to new diseases, rather than through warfare with colonists, as would commonly be assumed. Ethnic Europeans themselves are today the surviving branch of those who did not fall to the bubonic plague.  The plague wiped out 60% of Europes population in the 14th century alone.  The evolutionary consequences of this immense selective pressure are still very present in the immune systems of modern Europeans, and quite possibly gave colonists an advantage in conquest of Americas.