California Mountain Lions

        Puma concolor, or the mountain lion goes by many names. Puma, cougar, catamount and panther are just a few. While the mountain lion goes by many names, it's genetic code remains relatively the same. Although the mountain are not in direct danger of extinction, their population is decreasing at a high rate. The mountain lion itself is what is known as a indicator species. This means that the speices can be used as a great reference on how an environemnt is doing, and how well the environement has remained connected. The large cat also acts as an umbrella species. These "umbrella species" are extremely important biologically and ecologically. Umbrella species are usually greatly monitored and protected beceause in protecting them, many other species become protected indirectly. Due to this, conservation techniques have been put in place in many areas where the puma exist. However in a recent study to observe how geography changes genes, researchers stumbled upon something rather interesting.
      431 mountain lions from various location were used in a study to collect data about the levels of genetic diversity among the species. In order to accomplish this 12 microsatellites loci were analyzed in each cat. After looking closely at the data gathered, it was found that each cat had distinct genetic  subdivisions that were specific to the region they were from. It was found that cats from coastal regions displayed more heterozygosity than the cats sampled from inland areas. Heterozygosity is important in population genetics, as the heterozygote advantage plays a large role in species survival. Scientists came to the conclusion that geographic barriers like the Los Angeles Basin, the San Fransisco Bay and the Central Valley turned out to be enormous barriers to natural gene flow of the species. The disruption of gene flow can result in many things particularly different allele frequencies among the species. Metapopulations in Southern California have exhibited normal gene flow but recently human development has increased how hard it is for populations to travel, which in turn decreased gene flow. With this, human development has displaced many of these large cats leading them to environments their ancestors did not inhabit before, or into urban areas. These new environments present challenges for the species, one which they may not actually be able to survive.
    In essence this study provided conservationists with a ton of new data to analyze, think about and act upon in the coming years. Most importantly, it displayed an important concept. Conservation genetics, and genetic preservation. This study indicates that not every case can be treated the same way. Each population of these cougars has different genetic subdivisions, and faces different enviroenmtal cahllenges. From this work, scientists hope to come up with movement corridors in unpopulated regions, to help the pumas travel from area to area, and increase biological diversity.  Landscape-level conservation is not only crucial to the survival of this species, but crucial in helping the species become more heterozygotic.
      This study was awesome because it really shows the connectedness of species between each other. In protecting the mountain lion, you protect the big horn sheep, which in turns help stabilize plant growth, and the list goes on and on about the connectedness of the mountain lion to almost everything it interacts with. Population genetics are studied extensively with animal populations, and I hope to work with wildlife one day, so reading these articles get me excited for the future. Hopefully measures can be put in place so that these animals can travel more freely and give themselves a fighting chance against their ever-changing environment.


https://link.springer.com/article/10.1023/A:1024069014911

https://www.sciencedaily.com/releases/2018/12/181221142514.htm

https://www.scientificamerican.com/article/highways-fragment-southern-california-mountain-lion-gene-pool/
       

Studies on Human Genome Determine Why There is Little Neanderthal DNA in Modern Day Humans

Modern-day humans contain up to 4% of NeanderthalDNA in their genome. They shared a common ancestor with Neanderthals up until about half a million years ago. Humans and Neanderthals started to interbreed tens of thousands of years ago, producing human-Neanderthal hybrids. Over time, the prevalence of Neanderthal DNA has steadily decreased over human generations until it has reached its current amount.

The reasons as to why scientists believe this interbreeding occurred and why Neanderthals do not exist to this day is because of the small population sizes of Neanderthals. Because they originally tended to live in harsher climates than humans, population sizes were smaller to cope with the extreme conditions. This resulted in a higher amount of interbreeding in Neanderthal populations, leading to less gene variation and a lower chance of natural selection.

The scientists of this study used mathematical equations to predict how allele frequencies of Neanderthal DNA inthe human genome changed over time. They suspect that while the chosen alleles may be neutral in Neanderthals, they may pose a greater threat to hybrids, resulting in high mortality rates. Therefore, offspring of any surviving hybrids would have a greater chance of survival if the hybrid parent mated with a human, decreasing the amount of harmful Neanderthal DNA in the offspring. This repetition of surviving hybrids mating with humans, and the resulting offspring also mating with humans, lowered the frequency of Neanderthal alleles in generations over time. When the hybrids reproduced with humans, there was greater gene flow and any disadvantages from the Neanderthal DNA could be effectively bred out over time. The breeding habits and survival rates of different generations of hybrids and their offspring would result in the varying degrees of prevalence of Neanderthal DNA in modern day humans. This study is important in understanding the origins of modern-day humans and how we came to be.

http://www.nytimes.com/2016/11/09/science/neanderthal-dna-natural-selection.html?rref=collection%2Fsectioncollection%2Fscience&_r=0

http://www.nature.com/articles/srep37198

In Neanderthals’ DNA, Ancient Humans May Have Left Genetic Mark

In 1997, the first parts of Neanderthal DNA in a fossil was found. Since then, scientists have been able to use a number of Neanderthal bones to recover genetic material and even entire genomes. 1 to 2 percent of human DNA, of non-African people, has been found to be Neanderthal. This is the result of Neanderthals and the ancestors of Europeans and Asians interbreeding. The Neanderthal genes influence health conditions like allergies and depression. A study has also found that interbreeding in Siberia left Neanderthals with pieces of human DNA. This could of possibly come from an early migration of humans. 600,000 years ago humans and Neanderthals split from a common ancestor in Africa and eventually Neanderthals died 40,000 years ago. They share mutations with Europeans and Asians, but not Africans which scientists have used to conclude that humans interbred with Neanderthals after they left Africa.

Using a toe bone found in the Altai Mountains, a complete genome of a male Neanderthal was constructed and compared to modern human DNA to confirm interbreeding. They were also able to make a detailed reconstruction of Chromosome 21. Sergi Castellano , a geneticist at Max Planck, compared European Neanderthal DNA to genes found in Serbia. Dr. Siepel, who has developed models to trace DNA, compared genomes and inferred their common history. This included how their ancestors split and how large the populations of their ancestors were. Together they found an example of Gene flow, the Altai Neanderthals shared some mutations with living Africans, but not with Europeans and Asians. This would suggest that an African lineage of humans interbred with ancestors of Altai Neanderthals after they split from other Neanderthals. Dr. Viola, a paleontologist at the University of Toronto, thinks the best scenario is that humans expanded into the Middle East and interbred with Neanderthals there. They then migrated to Serbia, taking human DNA with them.

Effect of radiation on species in Chernobyl

 The Chernobyl disaster happened in Pripyat, Ukraine, where a nuclear reactor exploded releasing large quantities of radioactive particles into the atmosphere. It is now abandoned and there were many casualties as a result of exposure to high levels of radiation.


High doses of radiation can affect living tissue in various ways. One of those ways involves breaking strands of DNA.  A high enough dose can cause serious illness or death. However, low doses of radiation are not as lethal. Over time, it can cause genetic mutations which can lead to different types of cancers.


Dr. Mousseau, who is a biologist at the University of South Carolina, makes trips to Chernobyl to study the effects of radiation on different species on birds and insects. He has observed species in areas of varying radiation. In areas of higher radiation, Mousseau has noticed higher frequencies of tumors and physical abnormalities like deformed beaks in birds. He also noticed that insect populations decreased in areas of higher and higher radiation.


One of the biggest observations that Mousseau noticed was that one species of bird seemed to have adapted to the radioactive environment by producing higher levels of protective antioxidants, which correlates with less genetic damage. This discovery has led Dr. Mousseau to state that chronic exposure to radiation acts as a source of natural selection.


 Lastly, Dr. Mousseau noticed that birds in higher areas of radiation showed greater adaptation than those living in areas with lower radiation levels. There is no explanation for this, but it is an interesting observation to say the least.


The effects of radiation have always interested me. I find it amazing that a species of bird has possibly found a way to adapt to the radioactive environment at one of the worst nuclear disasters in history. I do not find it out of the realm of possibility that this discovery can lead to possible advancements in technology as we continue find ways to fight against cancer.