Many studies suggest that larger animals survive better in colder climates. When the temperatures increase smaller animals are better suited to survival. In some cases, warming climates cause larger fauna to die off. This is one of the leading hypothesizes of the decline of the mega fauna of the ice age. Many species that existed during the ice age, still inhabit the planet. One of these species is the coyote.
Fossil records show that coyotes during the ice age were much larger than their modern descendants. Fossils suggest that the coyotes sizes during the ice age where about fifty percent larger during that era. Unlike many other species that ancient coyotes coexisted with, the coyote did not die off. The species adapted to the warming environment, smaller coyotes were more likely to surivive. Through natural selection the species adapted to the new climate in which they inhabit.
The genotype of an organism is a major factor in determination of an organisms size. Coyotes with genotypes coding for smaller body size were more likely to survive in the warming climate. This dramatic change in the size of coyotes occurred in a very short period of time. This discovery supports the theory of evolution and genetic inheritance.
Salmon and trout are often stocked in areas of high human population to account for recreational fishing impacts on the population. By stocking the population is maintained at a level that satisfies the demands of recreational fishermen. Recently it has been realized that the long term effects of stocking are severely compromising the gene pool of wild stocks.
Fish in the wild, through natural selection, are adapted to their environment. Fish raised in hatcheries are raised in conditions where natural selection may run a different course. Stocked fish maybe adapted to a relatively stress free environment, and genes that normally would die off in the natural environment care allowed to make their way back into the native population. This can compromise the native populations gene pool making them less capable of survival.
Stocked fish come from a brood stock. Brood stocks are the reproducing fish that produce the progeny which are then stocked into the waters. The brood stock is often of the same species as the wild fish and often from a different population that has adapted to it original environment. For example, salmon were introduced into the Great Lakes and naturally reproduce there. Stocked salmon in the Great Lakes may come from a Pacific coast brood stock where they are adapted to the environment and diseases of the west coast. When the native and stocked fish interbreed it compromises the gene pool of the native fish.
Also, in this article, stocking fish can often hide the state of the native fish population. Artificially high populations because of stocked fish can hide a fishery that is imperiled due to overfishing, habitat loss, and a number of other threats.
The American Chestnut tree was once a dominant tree in the forests of the eastern United States. The tree was once the most economically important tree species eastern forests of the United States. The tree also had a very important role in the ecosystem of the forest, the tree produces edible nuts that many animals consumed. In 1904 the chestnut blight began annihilating the native chestnut tree population. The native chestnut trees did not have any genetic information for blight resistance in the entire population.
The blight is a fungus that was native to Asia where the Asian species of chestnut had resistance to the fungus. The fungus gets into the cracks of the bark and wounds on the tree and then kills the tree. American chestnut trees continue to sprout up but quickly succumb to the blight.
An American chestnut.
The American Chestnut Foundation has been working on breeding American chestnut with Chinese chestnut trees to yield an American chestnut tree with blight resistance. It is a large task to take on, they need to achieve a progeny that maintains almost all of the American chestnuts genetics while also having the Chinese chestnut’s genes for blight resistance. This is further compounded by the need to avoid overly inbreeding the species. When this is finally achieved the trees will be replanted throughout the eastern forests of North America. One day chestnut trees may once again populate the forests and reclaim its niche in the ecosystem and the economy.
There are other organizations trying to repopulate the forests with chestnut trees such as this group; Friends of the Rouge Watershed.
Research over the decades on Alzheimer’s disease shows that there is significant evidence that chromosomes 1, 14, 19, and 21 are linked to Alzheimer’s. The most common form of Alzheimer’s is Late-Onset Alzheimer’s Disease. This form of the disease is linked heavily to the gene APOE on the chromosome 19. Although there is a high consistency of individuals who have Late-Onset Alzheimer’s carry the APOE gene, many people who have Late-Onset Alzheimer’s do not carry the APOE gene. Other forms of Alzheimer’s are linked to other genes on chromosomes 1, 14, and 21.
Alzheimer’s research cannot fully link the disease to genetics. It is not completely known whether the disease is completely genetic or external factors have an effect on the disease. External factors that may cause alzheimer’s range from head injuries in early life to low levels of education. As research continues the true cause for Alzheimer’s will most likely become more clear.
Catfish have become a commercially important fish due to the increased use technology based around aquaculture. Fish farms throughout the southern United States now produce inexpensive and desirable catfish flesh. Increases in technology and practices have led to increased yields and increased quality fish.
Fish farms are now working on breeding fish for desired genetic traits; however, this is a multifaceted endeavor. The USDA has been reporting on the current goals in research with catfish genetics and also the completed advancements in catfish genetics for many years.
Currently, the main push of the research is being directed at breeding catfish for the most desirable characteristics. The two main traits selected for are increased reproductive efficiency and growth efficiency. USDA conducted experiments by crossing different catfish strains and producing genetic linkage maps. Chromosomal location were identified for disease resistance, reproductive efficiency, and growth efficiency. Researchers identified genes that caused changed expression in insulin growth factor or IGF. Increased levels of IFG lead to weight gain. Cross breeding different strains of catfish with higher resistance levels to bacteria led to offspring with a 10% increased survival rate.
Increased knowledge in genetics can help increase production in aquaculture; however, it is not limited to aquaculture but will help in all forms of agriculture to improve outputs.
Every organism traits are determined by their genes. The genes are expressed as a phenotype, the physical manifestation of the genetics. Some phenotypes are as simple to recognize as hair color, other phenotypes can be as difficult to recognize as an organisms reaction to certain drugs.
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Fainting Goats video clip.
In the case of goats, a certain genotype causes the goat to appear to faint when excited. This is considered a genetic disease called Myotonic congenita. When the goat is excited or frightened the goat has an involuntary response causing the muscles throughout the body to contract. When the goats are young they often fall over, appear to have fainted.
Most experts agree that first knowledge of this breed of goat appeared in the 1800′s. This genetic abnormality would appear to a very negative condition for a breed to have. Many people would think a genetic problem as severe as this would severely impede on the goats ability to survive.
This unique condition has lead to interest by humans as keeping myotonic goats as pets. Also, some argue that myotonic goats help protect herds of sheep and goats. A predator hunting a herd a sheep often causes myotonic goats to “faint.” Predators often investigate the “fainted” goats allowing the rest of the herd to escape. Oddly enough, reports say that more often than not predators leave “fainted” goats alone. It is surprising how a seemingly advantageous genetic disease can be beneficial to the organism.
Myotonic conditions do occur in other species, including humans. It is a genetic condition governed by CLCN1 gene in goats.
A study was conducted by University of Utah, investigating the trend of addiction within families. Researchers compile family trees and mark individuals that suffer from addictions. By doing so the trend, or lack of trend, can be seen. Addiction is affected by multiple genes; however, addiction is also affected by environmental effects. Due to difficulties of researching on human, many studies have been done on the effects of specific genes on addictive tendencies. Genes sequences, missing genes, duplicate genes, and more genetic variations have all been linked to addictive traits in organisms. In some cases the genetic variation would lead to increased rates of addictive tendencies; however, other genetic variations led decreased trends in addictive traits. For example, mice bred to lack cannabinoid receptor gene Cnr1 have a less satisfying experience with morphine. This shows how certain genetic variations can be beneficial for an organism to be less prone to addiction. Unfortunately, many genetic variations cause the organism to be more prone to addiction.
Genetic inclination to addiction does not mean you are born an addict; however, there are a lot of genes that have negative and positive effects on addictive tendencies.
Genetics have been proven to play a critical role in addiction in animals and humans. Environmental factors still play a crucial role in addiction. Both factors contribute to an organisms probability to develop an addiction in conjunction.