What are the problems associated with natural selection?
There are 3 types of problems that come from natural selection. They are directional, disruptive and stabilising. Directional selection is when an environment causes an extreme phenotype to be favoured over other phenotypes causing the frequency of the alleles to change over time in the direction of that phenotype.
Disruptive selection is when the two extremes are favoured at the expense of the average.
Stabilising selection is when the gene diversity lessens and the population is mainly focused on a particular trait. These are all problems that occur when the organisms that are least favoured have a gene that influences other species, or when the most favoured organisms have a undesired phenotype.
Disruptive selection is when the two extremes are favoured at the expense of the average.
Stabilising selection is when the gene diversity lessens and the population is mainly focused on a particular trait. These are all problems that occur when the organisms that are least favoured have a gene that influences other species, or when the most favoured organisms have a undesired phenotype.
How were these problems solved?
Directional Selection - Example One. If the environment is changing due to global warming, then some species that cant deal with increased heat will slowly be dying off. Humans can step in and fix this by trying to help prevent global warming more actively or by physically transporting these species to a different country that has a climate that suits the species better.
Disruptive selection - This can be illustrated with a population of giraffes. If there were high trees and short trees only the giraffes with long necks could reach the high trees and only the giraffes with short necks can bend down to the short trees. This results in average heights giraffes inability to reach either height tree. In time these giraffes will evolve so there are only tall or short necked giraffes. To solve this problem, humans could actively plant different height trees fulfilling the feeding needs of a wider range of giraffes
Stabilising Selection - An example of stabilising selection can be shown with chipmunks living in a limited variety of trees. The fatter, heavier chipmunks will break branches that they walk on, but the smaller ones cannot climb up the branches as they are too short. This means that the chipmunks will evolve to all be a very consistent weight and size. Humans could help to solve this by creating a more ‘chipmunk-friendly’ environment. This could be actioned by planting genetically modified trees with stronger and increased number of branches to cater to those chipmunks with more diverse genes.
Disruptive selection - This can be illustrated with a population of giraffes. If there were high trees and short trees only the giraffes with long necks could reach the high trees and only the giraffes with short necks can bend down to the short trees. This results in average heights giraffes inability to reach either height tree. In time these giraffes will evolve so there are only tall or short necked giraffes. To solve this problem, humans could actively plant different height trees fulfilling the feeding needs of a wider range of giraffes
Stabilising Selection - An example of stabilising selection can be shown with chipmunks living in a limited variety of trees. The fatter, heavier chipmunks will break branches that they walk on, but the smaller ones cannot climb up the branches as they are too short. This means that the chipmunks will evolve to all be a very consistent weight and size. Humans could help to solve this by creating a more ‘chipmunk-friendly’ environment. This could be actioned by planting genetically modified trees with stronger and increased number of branches to cater to those chipmunks with more diverse genes.
These giraffes have different length necks, the taller ones wouldn't survive as well as the shorter ones because most of the plants are lower down, close to the ground. http://www.newmarkhotels.com/wp-content/uploads/2013/04/24-April-sharpened_19.jpg
This chipmunk would be too fat to climb on the branches, they would snap. http://1funny.com/wp-content/uploads/2010/12/chubby-chimpmunk.jpg
This polar bear is being affected by global warming, as the ice that it lives on is melting. https://biodilloversity.files.wordpress.com/2011/11/polar-bear-clinging-onto-cracking-ice.jpeg?w=300&h=224
This chipmunk would be too fat to climb on the branches, they would snap. http://1funny.com/wp-content/uploads/2010/12/chubby-chimpmunk.jpg
This polar bear is being affected by global warming, as the ice that it lives on is melting. https://biodilloversity.files.wordpress.com/2011/11/polar-bear-clinging-onto-cracking-ice.jpeg?w=300&h=224
How effective are these solutions?
Directional Selection - This solution would be effective if the actions were imposed. Historically, humans have been too lazy to stop global warming. I feel humanity will only change with some kind of enforcement.
Disruptive Selection - This solution would be effective because there would be more giraffes, as they would have a higher selection of plants to eat, at different heights to cater to their different phenotypes.
Stabilising Selection - This solution would be partially effective. The problem with it would be when issues arise from other animals living around these genetically enhanced trees. There will be breeds of birds that cannot make their home in these trees anymore. This will effect not only them, but the small insects in the trees too. Their population will boom from the lack of birds eating them which could then have a carry on effect with other species and have a dramatic influence on the lives and sustainability of the plant and animal life in this environment.
Disruptive Selection - This solution would be effective because there would be more giraffes, as they would have a higher selection of plants to eat, at different heights to cater to their different phenotypes.
Stabilising Selection - This solution would be partially effective. The problem with it would be when issues arise from other animals living around these genetically enhanced trees. There will be breeds of birds that cannot make their home in these trees anymore. This will effect not only them, but the small insects in the trees too. Their population will boom from the lack of birds eating them which could then have a carry on effect with other species and have a dramatic influence on the lives and sustainability of the plant and animal life in this environment.
These giraffes have different length necks http://www.schattigedieren.nl/wp-content/uploads/2013/05/Giraffen.jpg
This chipmunk is the perfect size for this branch. http://www.soulshepherding.org/wp-content/uploads/2012/06/chipmunk-in-tree.jpg
This polar bear is suffering through the effects of global warming and has found a small patch of ice to cool him down. http://www.duskyswondersite.com/wp-content/uploads/2013/01/sleep-polar-beat.jpg
This chipmunk is the perfect size for this branch. http://www.soulshepherding.org/wp-content/uploads/2012/06/chipmunk-in-tree.jpg
This polar bear is suffering through the effects of global warming and has found a small patch of ice to cool him down. http://www.duskyswondersite.com/wp-content/uploads/2013/01/sleep-polar-beat.jpg