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.
The island rule means that the island does evolve certain animals into its own species, then that species fails and goes extinct. Both island evolution and extinction have been proven, however now they are now connected. The islands cause evolution, the evolution causes the extinction, and thus meaning that the island caused the extinction. Shown by numerous scientist and written books, both are correct, islands cause evolution and extinction.
BENTON, MICHAEL J. "Mass Extinctions." New Scientist 209.2802 (2011): i-viii. Academic Search Premier. Web. 13 Jan. 2014.
Annotation: This article discusses the different comparison between biodiversity and island size. This article argues that smaller islands can often be more diverse than larger islands. Although smaller islands have smaller niche constraints and immigration rates, the comparison to niche rates versus island size is greater than the
Throughout history, the world and its inhabitants have been subject to great change. Whether these changes are biological, ecological or geological they are all influenced by certain factors at play. Great changes take time to observe, usually longer than one's life would allow. The longer the change, the harder to identify the exact cause. When it comes to the species that inhabit the earth, it is notable that some species that lived and thrived long ago are now simply gone. The extinction of entire species of birds, mammals and amphibians occurs throughout time here on earth but the exact cause for their disappearance has been debated. In chapter two of "Twilight of the Mammoths" written by Paul S. Martin, the theories of extinction are challenged.
The reasons for these extinctions have been altered by sudden environmental change, pestilences, space rocks effects and people. Case in point, the immense Auk was a flightless winged animal that has to be wiped out in the mid-nineteenth century in light of the fact that it was slaughtered for its quills to make pads, for oil, angling snare, and food. At the point when the population of this bird started to decline, samples of the great Auk and its eggs have to be collectible and exceedingly prized by rich Europeans, and the loss of an expansive number of its eggs to gathering played part to the species'
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.
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.
Over 98% of all organisms that have lived on Earth are now extinct. A mass extinction event occurs when a large number of species die out within a small time frame (relative to the age of Earth). Mass extinctions are intensively studied for both cause and effect, as there is usually room for debate regarding catalysts that precede the extinction and the massive influx of new biological species that follows. There have been five major mass extinctions, dubbed the “Big Five,” that have wiped out at least 50% of the species living at those times. The most well known mass extinction of the Big Five, with the decimation of every species of non-avian dinosaur, is the Cretaceous-Paleogene extinction event (K-Pg). The K-Pg extinction occurred as ongoing natural disasters followed by an asteroid collided with Earth, which affected plant life, animal life, and hydrology (Cobb).
During the late Pleistocene, a mystery occurred in which large mammals went extinct in North America while they survived in other parts of the world. Scientists studying the late Pleistocene extinction provided a plethora of explanations, including overkill by humans, extraterrestrial events, and climate changes (Faith and Surovell, 2009). However, there was no unified explanation that they all agreed upon. Taking note of this, J. Tyler Faith and Todd A. Surovell conducted tests to discover whether the extinction was a single event or a long-term process. Their findings were important to other scientists in the same field, as they served as a guideline for their explanations of catalysts of the extinction.
In spite of the overwhelming amount of negative speculation, the practice of de-extinction might potentially produce some positive ramifications. According to Stewart Brand, a writer for National Geographic, humans should bring back extinct species “to preserve biodiversity, to restore diminished ecosystems...and to undo harm that humans have caused in the past.” If humans were to tamper with nature and bring back an extinct animal, desolate ecosystems which previously thrived, such as deserted islands, could be partially restored through their
slow extinction, or did it happen all of the sudden? These questions bring rise to many
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...
In 2002 population estimates ranged from 4 - 11 animals per hectare (habitat dependant) on one of the islands (627ha North Keppel Island), compared to an average density on the adjacent mainland of 0.2 – 0.4 individuals per hectare (Strahan, 1995). Possums were most likely introduced to islands in Keppel Bay after European settlement as a harvesting source for pelts. Genetic analysis has not iden...
The population of the Kakapo has rapidly declined over the last 200 or so years since the 19th Century. During this period, the kakapo could be found inhabiting both the North, South and Stewart Islands of New Zealand whereas at present day, the Kakapo can now only be found on only 3 small islands surrounding New Zealand. This huge decline in population has most definitely been caused by the colonisation of New Zealand, which brought along the introduction of animals such as Cats, Dogs, Rats, and Stoats. This exploration also destroyed much of the habitat the kakapo rely on, such as the fruit of the berry of the rimu bush. The invasion, along with the kakapo's high infertility rates (only 58 % of eggs hatch) and the fact that kakapo only reproduce once every 2-5 years have all contributed to the near extinction. The population is thought to have been somewhere in the 1000s before this period in time, compared to the 2012 population count of 126 Kakapo that reside on the Islands today.
Shah, Anup. Loss of Biodiversity and Extinctions. Global Issues, 19 Jan. 2014. Web. 19 May 2014.