Genetic Drift in San Francisco Garter Snakes

 

        San Francisco garter snakes are found along California's southern coast and live in aquatic and upland environments. The population has recently experienced significant habitat loss due to urban development and groups within the population have become isolated from one another. The isolated populations have generated cause for concern among conservationists due to the possibility of genetic drift. Genetic drift is the loss or disappearance of genes within a population, reducing genetic diversity overall. To determine if genetic drift is occurring in San Francisco garter snake populations researchers obtained small tissue samples from individuals in geographically isolated populations for genetic analysis. 

        Researchers used the tissue samples to quantify the DNA and establish the number of genes, compared loci, and determine the sex of the individuals. The DNA was then compared with individuals from other geographic sites. Researchers determined that the populations were experiencing significant genetic erosion due to their isolation. This genetic drift is crucial for conservationists moving forward since the species is currently endangered. The study published in 2020 determined that the populations were experiencing genetic drift, it would certainly be interesting to redo this study to determine if the genetic drift is increasing and what conservation efforts would be most beneficial. 

Galapagos and California Sea Lion Speciation

 

        Galapagos Sea lions are currently an endangered species native to the Galapagos islands. Galapagos sea lions are a member of the pinniped family and face threats such as plastic populations, habitat loss and change, and human activity. When it comes to the conservation of marine mammals, their genetic information is crucial to better understand their ecology and how to protect their populations. In 2007 researchers dove into the genetic composition of Galapagos Sea lions and California Sea Lions to determine if the two were distinct species. Through the analysis of mitochondrial DNA and phylogenetic reconstruction, they determined that the common ancestor of Galapagos Sea Lions and California Sea Lions existed 2.3 ± 0.5 mya. Additionally, they discovered that gene diversity is 14% lower in Galapagos Sea Lion populations.

         The reduced genetic diversity in Galapagos Sea Lions has large implications when it comes to species conservation. When the article was published the species was listed as threatened and as of 2023, the population is listed as endangered. For the population to be able to recover sustainably, the reduced genetic diversity should be taken into consideration. To properly conserve the population in the future, any breeding efforts should be carefully orchestrated to ensure the best genetic diversity possible. 

Rat Species Has No Y Chromosome!

Amami Spiny Rat

A team of researchers at Hokkaido University in Japan has figured out how a species of rat is able to survive and reproduce despite not having a Y chromosome. The rat species they studied was the Amami spiny rat (Tokudaia osimensis), a rodent native to the island of Amami Ōshima in southern Japan. The species, also called the Ryukyu spiny rat, is unique in that males do not have a Y chromosome and females only have one X chromosome as well. Previous attempts to study the rat have not been able to reveal how males are able to develop within the population with no Y chromosome. Typically in mammals, a gene on the Y chromosome called SRY tells the organism's body to express male genes like the SOX9 gene for testes. Not having the Y chromosome scientists were stumped at how males could develop. Lead researcher, Asato Kuroiwa, and her colleagues at Hokkaido have now discovered the answer! The secret was looking at the autosomes, non-sex chromosomes, in the rat. On chromosome 3 they found that one copy had a duplicated region next to the SOX9 gene. The duplication increases the activity of the SOX9 gene and it is able to code for testes. This duplicated region effectively replaces the SRY gene on the Y chromosome and explains how males of this species are formed. If a rat has the duplication region it acts as a proto-Y and the rat will be a male, and if the duplication region is absent, it acts as a proto-X and the rat will be a female. Further work to explore this is limited as the rat is an endangered species but the research so far has shown an amazing trait inherited by this rat population. The researchers predict the trait appeared about 2 million years ago when the Amami spiny rats diverged from their ancestors with a Y chromosome. Kuroiwa believes that a mixed population existed initially on the island but then a natural disaster like flooding or rising seas left mostly rats without the Y chromosome and over time the rats reproduced and evolved into a new species with this trait. 

Personally, this was my favorite article to read so far about genetics. I find it incredible that a species can exist without a Y chromosome and that another chromosome was able to replace its function to make males. This is a really interesting example of population evolution, genetic drift, and speciation. I hope that these rats can be studied more to learn about this unique and interesting trait. 

Genetic Variation and the Amish

 

 

Genetic variation among the Amish is extremely low. This is due to the Founders Effect. Amish genetics can be dated back to German-Swiss settlers back in the 18th century. Amish culture is very secluded and strict. They cannot marry or have children with anyone outside of the Amish faith. This has unfortunately led to an increase in inter-family marriages. Some rare genetic traits have begun to arise due to the limited gene flow. Amish populations have seen an increase in mitochondrial mutations. Such mutations include mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes.

https://pubmed.ncbi.nlm.nih.gov/15466077/

https://www.cbsnews.com/news/genetic-disorders-hit-amish-hard/

Chernobyl and Honey Bees

 

Chernobyl was an ecological disaster that happened In Ukraine in 1986. Aside from the ecological issues that the chemical plant explosion caused, genetic issues also arose. The problem was that radiation was all over the environment after the chemical plant explosion. Radiation causes many immediate and long lasting health effects to organisms including; burns, cancer, cardiovascular disease, and damage to blood. Since some of the immediate health effects from radiation has already been discovered, this article goes over a study about long lasting health effects. 

The University of Sterling did an experiment on Honey Bees and high radiation exposure. The study showed that less Queen Bees were produced, meaning there was stress in the colony. Another thing that was noted was that the experimental bumble bee colonies grew at a slower rate. These studies show that future bee populations around the Chernobyl area will begin to decline from the radiation levels. This is a good study to look at for the future so that we know the long lasting effects of a future chemical plant explosion.

Chernobyl: bumblebees still at risk from radiation nearly 35 years on (theconversation.com)

Radiation Health Effects | Radiation Protection | US EPA

Swedish, Finnish, and Russian Wolf Genome All Closely Related

 This article is about the confusion behind the Scandinavian wolf genome in terms of evolution and migration patterns. At Uppsala University a study was conducted using the Y-chromosome of the DNA, the paternal lineages showed that the genome had not been infected by dog genetics and the migration pattern was determined to come from England. The reason this is interesting is due to the migratory patterns of wolves on the specific Scandinavian peninsula. This can provide information into the future with regards to species populations and climate change. With regards to dog genetics and wolf hybridization the article states that if crossbreeds were allowed to reproduce this can jeopardize the integrity of the wolf genome. With comparison to one hundred different dog breeds, the study had shown that the population did not have any implications due to any dog genome. This study will be interesting to see for future populations and understanding the genetics of how climate change will effect migratory patterns and move populations closer and farther apart. Only time will tell with regards to how important this information will be. 

https://www.sciencedaily.com/releases/2020/11/201110112508.htm

https://onlinelibrary.wiley.com/doi/10.1111/eva.13151

Did The Ancient Egyptians Farm Ibises?

Ibises are a bird native to Africa with a long scythe-like beak that hunt by wading through rivers. They are a sacred animal to the ancient Egyptians. Their god of writing and wisdom, Thoth, is often depicted with the head of an ibis. As an offering, the Egyptians would mummify ibises and place them in catacombs.


Scientists have discovered rooms filled floor to ceiling with these sacrifices. This raises an interesting question. Where did these birds come from? Ibises have not been native to Egypt in hundreds of years. It is unknown if they migrate in large enough flocks with high enough frequency to provide the quantity of birds required for these uncovered offerings. A theory offered instead is that they were farmed by Egyptians.

The mummification process is fantastic at preserving DNA. Scientists were able to extract mitochondrial DNA from several birds. Due to controlled breeding, you would expect to see lower levels are variance between domesticated individuals. Instead, scientists found the same levels as measured in modern day ibis wild populations. While this is not enough evidence to rule out the possibility of Egyptian farms, it suggests there might be more to the story than we currently know. I thought this was an interesting application of mitochondrial DNA. Since the mitochondrial DNA is passed down from the mother, I wonder if its possible to trace the lineage of a modern ibis to one of these mummified birds.

Links:
https://search.proquest.com/nytimes/docview/2314696925/C49933956F5741C4PQ/19?accountid=29054
https://www.smithsonianmag.com/smart-news/dna-suggests-ancient-egypts-millions-ibis-mummies-were-wild-caught-birds-180973556/ 

Melanin in Manta Rays

There are only two species of fish with dark melanin spots on their skin. Both of these species are manta rays. Some manta rays exhibit dark spots on their otherwise completely white underbellies. These dark blotches are caught the eye of researches for that reason. They figured that there must be a reason that melanin is so rare in the ocean and there must be a reason that rays express it.
 
Manta rays have very few known predators. One theory that offers an explanation as to why is that their white underbellies makes them difficult to see against the sky. In that case, the dark spots should be selected against. After following a population of melanistic rays, the researches determined that the dark spots do not affect fitness.

It is also possible that the gene causing this mutation is closely linked with another gene which is improving fitness. Perhaps there is an advantage within the manta rays that we cannot see which has the side effect of these dark splotches. However, as mentioned earlier, initial research shows that these spots do not appear to affect fitness.

Their new hypothesis is that the mutation may be a product of genetic drift. Not all populations of rays have this trait. Some have up to 40% while others have nearly none. It is believed that this neutral trait appeared as a mutation in a population and increased in frequency through random chance. The members of this population mated with other populations, spreading the gene further. If that is the case, this gene can be used to traced back through several generations and better understand migration habits of manta rays. Rays are currently a vulnerable species. Being able to predict where they will go may help the conservation effort. I hope that they find success in the conservation endeavor because mantra rays are an awesome animal that I want to see more of in the future.

Links:
https://www.nytimes.com/2019/10/14/science/manta-rays-black.html?searchResultPosition=14
https://marinemegafaunafoundation.org/blog/scientists-explore-the-occurrence-of-black-manta-rays-in-the-indo-pacific/

Why Textbooks May Need to Update What They Say About Birth Canals

          For years it has been claimed by doctors and textbooks alike that diet during the adolescent years of females is one of the major reasons for a wide pelvis and better birth canal. Recent studies show that our view of the female human pelvis is quite wrong, and that the shape of the pelvis also depends on where the female comes from rather than just diet. What we consider to be a "normal" pelvis dates back to the early 1900's and is wildly different from the female pelvises we see today. 

          Two scientists, Dr. Betti and Dr. Manica, conducted a study of 348 female human skeletons from all around the word in order to compare and contrast each body's structure. All in all, they found that not only were the pelvic structures different, but that arm and leg length also varied significantly in each separate population. Narrowing it down, they realized that pelvic structure relied on the geographical location of the individual, "People of sub-Saharan origin generally had the deepest pelvises back-to-front, while Native Americans had the widest side-to-side. Europeans, North Africans and Asians fell in the middle of the range". On a genetic level, the scientists discovered that a fluctuation in gene frequency was related to the variation in pelvic shape. Dr. Betti also believes that geographical natural selection has something to do with the shape of the pelvis as well and use the example of a siberian woman tending to have a birth canal that is much wider at the top because it will, "make the individual stockier" and hold weight better to keep her warm. 

"A comparison of two human pelvises: The top is more oval in shape, representative of Europeans, North Africans and Native Americans. The bottom is more circular, representative of sub-Saharan Africans and Asians."CreditCreditLia Betti

          The reason that I chose this article is because as a woman I believe it is important to know about your body, especially if a new fact that we previously did not know about arises. It is important to become knowledgable about your body. Now that we know this information as a society, it will make a lot of women look at child birth differently. More importantly, I think this is imperative for doctors to know and learn about. Now we know that pelvic structure difference is much grander than we previously imagined. Learning this will help us better serve women during child birth and make it much safer for both mother and child. 

Related Article 
Original Article 
         

Australia’s Endangered Quolls Get Genetic Boost From Scientists

In northern Australia, quolls' (squirrel sized marsupials that eat any animal smaller than them) population is dying. Their diet of cane toads (a poisonous species) nearly led them to extinction. But in Queensland, scientists found that the quolls there did not feed on cane toads and had successful populations. This was because they had a gene that prevented them from eating toads. Scientists found that if you bred the Northern Australia's quoll with the Queensland's quoll, their offspring had the toad-aversion gene and used this to increase their population. Scientists believe that this method can help increase declining populations of any endangered species.

While some argue that it is "unnatural" to mess with nature this way, I think that it is a great way to keep everything balanced. Science was discovered to help living things thrive, so it only makes sense that we use this knowledge wisely.

Article Link
Related Article

Low protein diet in early life increases lifespan in fruit flies

            Scientists from The Francis Crick Institute used Dorsophila melanogster to understand how diet in the early life can affect the life span. The scientists wanted to conducted this because they see evidence in humans and many other mammals, that a early diet alters the risk of developing cardiovascular disease and diabetes. The scientists from Francis Crick Institute found that adult fruit flies release a toxin from their skin that shortens their life span. As well a low protein diet caused less toxin from being released. Not only does the skin lipids have negative effects, but beneficial functions as well, preventing dehydration. The scientists also wondered if their lifespan was shortened when densely populated. The results showed skin toxin effect population density on lifespan. This article was very interesting but very vague and repetitive. The article should have provided a little more information on how the experiment or research was conducted. The food that was given or how the diet was changed could have been provided. Lastly, the article was interesting because I learned new things about how skin toxins effect the lifespan of fruit flies. This could lead to further experiments on humans and other mammals to see if early diets could effect the lifespan.



https://www.sciencedaily.com/releases/2017/11/171109093258.htm

http://www.dailymail.co.uk/health/article-5065585/Low-protein-diet-early-age-DOUBLES-lifespan.html

Lack of Genetic Diversity? No Problem for the Island Fox!

The island fox may only weigh a little over two pounds when full-grown, but even this is not the most surprising aspect about these foxes. According to this scientific journal, researchers have discovered that the island foxes are nearly identical, genetically speaking. Robert K. Wayne, a geneticist at the University of California, has been studying the foxes since 1990 trying to understand how these foxes are able to thrive, especially considering one island fox community has a record for the least genetic variation in a sexually reproducing species. After sequencing the genomes from each of the six subspecies, the DNA was found to be virtually identical. There are a number of possibilities as to how these foxes have been thriving for thousands of years, such as being the top predator without exposure to inbred difficulties and the genes being programmed to be switched on and off, called epigenetics.

This fox phenomenon is very intriguing, especially since even the scientists who have been researching this topic for nearly 30 years still do not know exactly why or how these foxes are able to thrive how they are today. Another interesting aspect of this article was the option to interbreed the subspecies in order to increase their genetic diversity. There was a promising instance in which Florida panthers interbred with a Texas subspecies in which the new genes helped the Florida population to grow. However, I would have to agree with Dr. Wayne in which he would not advise this "genetic rescue" unless there was strong scientific evidence that the low genetic variation was significantly hindering the fox's populations.

The original article can be found here.

How We Got Here: DNA Points to a Single Migration From Africa

The question of where humans came from has been one of the biggest in science for years. Three separate teams of geneticists from different places, all sampling different people, sequenced the genomes of 787 people from hundreds of different populations and found that all humans came from a single population from Africa between 50,000 and 80,000 years ago. The genomes were taken from a variety of people from every continent and were examined separately to finally come up with the same conclusion as to where people came from. Before now, there were very few sequenced genomes from people outside of population centers like China and Europe, but this new data with genomes from indigenous populations adds great value to our understanding of human DNA. 

The first team was Dr. Willerslev and a few colleagues who first sequenced the genome from a century-old lock of hair of an Aboriginal Australian. The results raised many questions, so the group joined David W. Lambert and the University of Oxford to obtain DNA from people from Papua New Guinea and from Aboriginal Australians to sequence. Mait Metspalu from the Estonian Biocentre sequenced genomes mostly from populations from Europe and Asia.  David Reich and his team from Harvard Medical School formed their database of genomes from people from all six inhabited continents. All coming up with the same results, the teams each established that there was an exodus from Africa 80,000 to 50,000 years ago, resulting in the populations we have today. There is also evidence of other groups migrating from Africa much earlier than 80,000 years ago, but these groups have since disappeared, having been wiped out by others who came after them who were stronger in number or in technology.