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Presently, the rate of species extinction is occurring several thousand times faster than has been observed over geologic time. (Purvis, E., & Mace, 2000) Though they represent a minority of all species, island species make up 75% of animal extinctions since the 16 000's. Because of traits inherent to islands, including isolation and small geographic range (Purvis, E., & Mace, 2000), islands are more susceptible to extinction than the continents. This results in a disproportionate ratio of island to continental extinctions. For example, 20% of the world's bird species inhabit islands, but of historical bird extinctions, about 90% were islanders (Frankham, 1997). With the endemicity that follows island isolation (particularly oceanic islands) often comes a direct correlation between local and global extinction. Low population numbers add to the threat of extinction. Generally, the more endemic a population, the greater the extinction rate (Purvis, E., & Mace, 2000). In the absence of mammalian or reptilian predators, unique island species do not develop the evolutionary experience required to cope with alien species upon their introduction. In New Zealand, the extinction rate of bird species is positively correlated to its level of endemicity (Duncan & Blackburn, 2007). This endemicity lends itself to the development of traits which increase their susceptibility to predation, especially large size, flightlessness and prey naiveté. Of island extinctions over the past 50 000 years, human activities (eg. invasion, alteration of environment, over-exploitation, etc.) have been the primary cause (Duncan & Blackburn, 2007). Also cited as attributing to the extinction of island species is inbreeding depression (Frankham, 1997).
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Frankham, R. (1997). Inbreeding and Extinction:Island Populations. 665-675.
Hockey, P. A., Wanless, R. M., & Brandis, R. v. (2011). Demographic resilience of territorial island birds to extinction: the flightless Aldabra Rail Dryolimnas (cuvieri) aldabranus as an example. In Ostrich (pp. 1-9). Pretoria: Taylor & Francis.
Jamison, I. G. (2007). Has the debate over genetics and extinction of island endemics truly been resolved? In Animal Conservation (pp. 139-144).
Purvis, A., E., J. K., & Mace, G. M. (2000). Extinction. In BioEssays (pp. 1123-1133). Berkshire: John Wiley & Sons, Inc.
Smith, K. F., Sax, D. F., & Lafferty, K. D. (2006). Evidence for the Role of Infectious Disease in Species Extinction and Endangerment. In Conservation Biology (pp. 1349-1357).
Ward, P. (2002). Lost Islands. In Rivers in Time (pp. 229-260). Columbia University Press.
In this paper Martin is arguing that late quaternary or near time extinctions where caused by human activity or as he calls it “overkill”. Martin recognizes that there have been many forces that have triggered extinctions in the planet on the past but disagrees with the idea that near time extinctions where caused by some commonly believed causes like climate change, disease or nutrient shortage. He argues that the arrival of humans to different continents, islands and the subsequent excessive hunting, the introduction of diseases and other competitors and predators was the cause of extinction of a great number of species “As our species spread to various continents we wiped out their large
Madagascar is one of the most diverse areas of land that has undergone evolution totally independent from surrounding continents. The plant and animal species located on the island are all endemic to the island, meaning all are native species. The amount of diversity is very high compared to that of other continents and the species found here cannot be found anywhere else in the world. Currently all organisms located on this island are in danger, even the humans. Much damage has already been done, yet each year the land seems to die even more. Many species are dying off rapidly and drastic measures will have to be taken to stop all of these species from becoming extinct.
...ted investigations of sediment archives in the crater lake of volcano Rano Raraku which contradict this hypothesis. On the basis of pollen data they found no evidence for a significant impact of rats proceeding anthropogenic woodland destruction” (2008, p. 24). Another scientist also found evidence that the rats were not abundant and was valued as currency for the Polynesian people. Brown (2006 [1924]) found that the Pacific rats were valued as currency by the islanders in the past, this report shows that rats were not abundant, but few on the island, and so the islanders will look at the animals as a valuable food source, not as a major environmental problem (2006 [1924]). Meith also conducted some research based on the intensive analysis of soils and sediments at several sites, and he also disagrees with the hypothesis of a major rat overpopulation (Mieth, 2010).
In order to better understand these "implications," it is necessary to define and explain the major theories regarding North American megafaunal extinction. The two most widely supported theories are those of environmental change and overkill. Two theories finding less support within the field are those of hyperdisease and "keystone herbivores."
Clinical Infectious Diseases, 49(3), 438-443. Doi:10.1086/600391. See full address and map. Medicare.gov/Hospital Compare - The Official U.S. Government Site for Medicare (n.d).
The Galapagos Islands, located about 600 miles west of continental Ecuador, contain a rich history of settlement and exploration and represent a living example of evolution that is still relevant today. For centuries, this chain of volcanic islands has been used uniquely by various cultures based off distinct needs. What has remained the same however is the fact that island isolation has forced many animal and plant species to adapt differently from one another based off their island’s environmental conditions, creating a living model of microevolution over time. Today, these models tend to be the primary resources used by biology professors when teaching their students evolutionary topics.
Adjoua Diby Anthropology 101 Primate in Peril Some animals’ species are disappearing because of human interference. According to ‘’Diversity Component of Impending Primate Extinctions,’’an article edited by Elwyn L Simons from Duke University Primate Center , the ecosystem may be negatively affected due to the extinction of species. It is well known that each species is essential to our environment.
Long-term survival of a species depends on its ability to adapt to changing environmental conditions (Murphy, 1994). Genetic diversity within a species, which has taken 3.5 billion years to evolve, makes adaptations to these changing environments possible. Unfortunately, the rate of extinction of genetically diverse organisms is rapidly increasing, thus reducing this needed biodiversity, largely due to the human impacts of development and expansion. What was an average of one extinction per year before is now one extinction per hour and extinct species numbers are expected to reach approximately one million by the year 2000 (WWW site, Bio 65). As a result governmental and societal action must be taken immediately!
In the video, “The dawn of de-extinction. Are you Ready”, Stewart Brand, introduced us to term de-extinction, the process of creating an organism that is extinct, and the global benefits of this process. In addition, Mr. Brand mentioned how humankind didn’t realize the biological impact of extinction until 1914, when the last female passenger pigeon died at the Cincinnati zoo. Moreover, how the number of this specie went from five billion birds to zero in couple decades, because of the out of control commercial hunting and other human activities. On the other hand, this specific consequence of the commercial hunting made people realize that the extinction of other species, like the American bison, will happen and needs to stop. Subsequently,
Even if scientists were able to successfully resurrect a species, the ecological niche that it once occupied will not have remained vacant waiting for it to return. Furthermore, there are very serious risks associated with resurrecting extinct organisms such as the reintroduction of diseases and the potential for abuse of power that should not be ignored. As I conducted the necessary research and debate preparation with my team, I found that my initial perspective was reinforced. My colleagues presented compelling cases against de-extinction, and going into the debate, I felt that we would be the undisputed champions. However, as I considered the arguments presented by my opponents during the debate, there was one argument that really struck me. Shelby drew upon an analogy to the space race to emphasize that the technology necessary to accomplish de-extinction has already been largely developed. She suggested that de-extinction is no longer a question as to whether or not species resurrection is possible, but rather a matter of who
Several mass extinctions have occurred during the Earth’s history. The Cretaceous – Tertiary Boundary (K-T) Extinction caused the loss of at least three-quarters of all species known at that time including the dinosaurs. The cause of this mass extinction is a controversial subject among scientists but the fossil evidence of it’s occurrence is abundant.
Extinction, although not as pleasant a concept as the idea of adapting to ones surroundings, plays just as large a role in natural selection as anything else. As one adaptation of a species proves beneficial, and as that variation begins to propagate, the original, less advantageous variant will die off. It is the unchanged species that are in immediate conflict with the species undergoing the natural adaptation that stand to suffer...
slow extinction, or did it happen all of the sudden? These questions bring rise to many
Over a long period of time organisms on an island change so they can no longer interbreed with organisms on different islands, the inability to interbreed in known as reproductive isolation. Reproductive isolation is due to Geographical isolation. A population can be geographically split in many ways which include Rivers form, Sea levels rise and fall, walls getting build, continents drift, climate isolation etc. If the environment conditions change for these populations they would then adapt to that environment, hence as long as they is no Gene flow between the two populations, they would genetically become different that they could no longer interbreed. An example of this includes a species of birds that once lived together, however now live on separate nearby
One of the big causes of extinction or the endangerment of species is foreign species entering a habitat. This species that are not native to the land can disrupt the food web in that community. These species take control of the food web and endanger some of the other species. The native species become endangered and over the course of many years they either adapt to their new way or life, the foreign predator leaves or is killed off due to the different environment, or the species is killed off and becomes extinct. Organizations like the “World Wild Li...