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However, not all founder effect studies are initiated after a natural disaster; some scientists study the reinstatement of a species that became locally extinct. Hajji & others and Hundertmark & Van Daele studied the current population statuses of past founder effects in Corsican red deer and Alaskan elk, respectively. Corsican red deer are still listed as an endangered species, decades after a severe bottleneck (Hajji & others 2008). They inhabit the Tryrrhenian islands and surrounding mainlands currently, and before the bottleneck, but Hajji & others wanted to know how the deer originally got to the islands, and from what parent population or species they were derived. Through molecular analysis they were able to determine a possible lineage, with red deer from the islands of Corsica and Sardinia being the most related to one another (Hajji & others 2008). These results are promising, as the island of Corsica was repopulated with red deer from the Sardinian island after the original Corsican red deer population went extinct, and the deer now inhabiting the island of Corsica are diverging from those inhabiting Sardinia (Hajji & others 2008). Its founder effect consequences are still a work in progress. Hundertmark & Van Daele examined the genetic differences between a parent population of elk on mainland USA, Washington and the growing population fertilized by eight founding elk on an Alaskan island. After 80 years, this island population has genetically and allelically diverged significantly from the parent population in Washington, as a result of the founding individuals’ lesser genetic diversity (Hundertmark & Van Daele 2010). When statistically analyzing the rapid growth of the island population, Hundertmark & Van Daele came to the conclusion “…that a severe bottleneck followed by rapid population growth may be undetectable using available tests.” Kolbe & others set up a pair of genetically sequenced and morphologically examined lizards on seven small islands to watch each new population’s growth and adaptation to its new environment. Specifically, they were looking at the effects on limb length and perch width, both widely varying phenotypic ranges in the parent population (Kolbe & others 2012). Unfortunately, immigration did occur, but the founder effect and adaptive differentiation, which could eventually lead to peripatric speciation, were statistically and biologically significant between the island populations after a few years (Kolbe & others 2012). The authors also point out that although adaptive differentiation is significant, the differences between island populations best reflect the differences between founders and their genetic diversity that has been passed down through the generations (Kolbe & others 2012).

____________________________________________________________________________________________________________ FINAL DRAFT STARTS HERE

Genetic drift can be defined as a phenomenon that decreases the amount of alleles present in a population, which results in different allelic frequencies than that of the original population, and possible speciation in the long term (Founder). Genetic drift occurs by multiple mechanisms, one such being the founder effect (Welcome). The founder effect refers to an event where, by choice or by random natural occurrences, a few individuals are separated from the original population, forming a new population of a more limited genetic diversity (Welcome). Similar to the founder effect is that of the bottleneck effect (Welcome). Generally, the bottleneck effect refers to the aftermath of a random natural occurrence, such as a hurricane or tsunami, which decimates all but a few individuals of a population (Welcome). The resulting genetic diversity and gene pool after a bottleneck event are also significantly depleted (Welcome). Therefore, the bottleneck effect is an example of the founder effect in respect to the dramatic decrease in genetic diversity (Welcome). However, the bottleneck effect is dissimilar in that the founder effect also applies to situations in which the original population remains intact (Welcome). Speciation is the occurrence by which two or more populations diverge drastically enough to be classified as separate species (Abbott 1974; Barraclough & Savolainen 2001; Mayr 1969; Welcome). This can come about through geographical separation, aka allopatric speciation, severe morphological differences, reproductive isolation, and/or niche partitioning (Matute 2013; Welcome). Named methods of speciation include allopatric, peripatric, parapatric, and sympatric, but with respect to island ecology, peripatric speciation, a special classification of allopatric speciation, is the most likely outcome of a founder effect (Welcome). Peripatric speciation refers to geographic isolation between populations which specifically concerns islands (Welcome). However, when the original population remains, the founder effect does not necessarily lead to speciation (Hundertmark & Van Daele 2010). Immigration from the original population allows for an influx of genes and can increase genetic diversity, which negates any consequences of the founder effect (Hundertmark & Van Daele 2010). Unfortunately, at our current level of knowledge, we lack a statistical model that can predict the outcome of a bottleneck or founder effect in nature. No scenario is identical, as varying habitats, communities, natural occurrences, selection pressures, mutations, and the founders’ genetic contributions each play a role in determining the genetic makeup of the new population many generations into the future (Kolbe & others 2012). However, just because we do not currently have the all of the answers does not mean that there are no more answers to be found. Quite a variety of experiments, in the lab and in the field, have been conducted in attempts to pin down all of the effects on a populations’ genetic diversity following a founder effect, as well as the elusive statistical model predicting such effects. An experimental setup for testing the founder effect is that of utilizing a deserted or mostly deserted island(s) as a breeding ground for gene sequenced individuals; at least one male and one female. More controlled and less controlled experimental setups have also been used in the testing of the founder effect. Mayr (1989) and Abbott (1974) conducted extensive research on bird speciation in the tropics and around Australia, respectively. Both came to a similar conclusion; morphological variations between geographically separated and niche partitioning populations have caused the initiation of subspecies and new species. Abbott (1974) focused on identifying the morphological differences between the islands’ species and how competition and niche partitioning may have played a role in their divergent evolution. Mayr (1989) focused on the physical or geographic methods of separation and their resulting levels of speciation, completed, parapatry, hybridization zones between similar species, and temporary isolation. However, birds have the ability to fly, or leave an area, allowing gene flow between populations and decreasing the chance of speciation. Hajji & others (2008) and Hundertmark & Van Daele (2010) studied the current population statuses of past founder effects in Corsican red deer and Alaskan elk, respectively. Corsican red deer are still listed as an endangered species, decades after a severe bottleneck (Hajji & others 2008). They inhabit the Tryrrhenian islands and surrounding mainlands currently, and before the bottleneck, but Hajji & others (2008) wanted to know how the deer originally got to the islands, and from what parent population or species they were derived. Through molecular analysis they were able to determine a possible lineage, with red deer from the islands of Corsica and Sardinia being the most related to one another (Hajji & others 2008). These results are promising, as the island of Corsica was repopulated with red deer from the Sardinian island after the original Corsican red deer population went extinct, and the deer now inhabiting the island of Corsica are diverging from those inhabiting Sardinia (Hajji & others 2008). Its founder effect consequences are still a work in progress. Hundertmark & Van Daele (2010) examined the genetic differences between a parent population of elk on mainland USA, Washington and the growing population fertilized by eight founding elk on an Alaskan island. After 80 years, this island population has genetically and allelically diverged significantly from the parent population in Washington, as a result of the founding individuals’ lesser genetic diversity (Hundertmark & Van Daele 2010). When statistically analyzing the rapid growth of the island population, Hundertmark & Van Daele (2010) came to the conclusion “…that a severe bottleneck followed by rapid population growth may be undetectable using available tests.” Hedrick & others (2001) studied the founder effects of a bighorn sheep stock population that contributes to all bighorn sheep populations in northern Mexico. This stock population was bred from 20 individuals, and their relative lack of genetic diversity is apparent in the current population and its outsourced individuals (Hedrick & others 2001). However, when some of the female sheep were brought to the island the population now inhabits, they were already pregnant (Hedrick & others 2001). Though these lambs represent a small influx of added diversity, more diversity is always beneficial from an adaptive standpoint. Hedrick & others (2001) model a handful of equations for genetic drift and heterozygosity on their data, which is a step forward, even if the equations are solely explanatory of this one population or species. The authors also recommend bringing in sheep from an unrelated population to broaden the genetic diversity available and ensure that the inbreeding coefficient and other detrimental effects of a limited gene pool do not become prevalent (Hedrick & others, 2001). Kolbe & others (2012) set up a pair of genetically sequenced and morphologically examined lizards on seven small islands to watch each new population’s growth and adaptation to its new environment. Specifically, they were looking at the effects on limb length and perch width, both widely varying phenotypic ranges in the parent population (Kolbe & others 2012). Unfortunately, immigration did occur, but the founder effect and adaptive differentiation, which could eventually lead to peripatric speciation, were statistically and biologically significant between the island populations after a few years (Kolbe & others 2012). The authors also point out that although adaptive differentiation is significant, the differences between island populations best reflect the differences between founders and their genetic diversity that has been passed down through the generations (Kolbe & others 2012). Government work on species introduction and the founder effect has also been conducted, in this case, on reef fish species (Planes & Lacaillon 1998). Of the eleven species intentionally introduced to the Hawaii region, only three have since begun to thrive and adapt to the new environment (Planes & Lacillon 1998). Additionally, those three species present data that there are occasions in which the genetic diversity of a random sample, taken from the parent population, can be similar to that of the parent population, which results in little to no loss of genetic diversity (Planes & Lacillon 2012). Even though the species in question are all fish, it is also notable that little to no immigration has been observed, despite the lack of physical boundaries between the founding and parent populations (Planes & Lacillon 2012). The authors also make a point of effective population size and how this, instead of the available gene pool, determines the consequences of the founder effect (Planes & Lacillon 2012). In all of the above scenarios, the founder effect has established a loss of genetic diversity and led to adaptations that may not have arisen if the diversity was greater (Welcome). Each scenario is different in the duration, number of generations, and geographic aspects, but the founder effect is still apparent. Studying the founder effect is still a major priority today because of the lack of a model that could allow introduction of the least number of individuals into a new setting and thrive on a wide distribution of genetic variation (Planes & Lacillon 2012). Once a model is discovered, however, it is unlikely these types of studies will disappear, as they are prime examples of genetic drift, adaptive differentiation, and eventual speciation, and will continue to test and retest such a model. References Abbott, I. 1974. Morphological changes in isolated populations of some passerine bird species in Australia. Biological Journal of the Linnean Society 6: 153-168. Barraclough, T. G. & Savolainen, V. 2001. Evolutionary Rates and Species Diversity in Flowering Plants. Evolution 55(4): 677-683. Founder effect. (2014, July 21). In Wikipedia, The Free Encyclopedia. Retrieved 16:02, September 14, 2014, from http://en.wikipedia.org/w/index.php?title=Founder_effect&oldid=617833733 Hajji, G. M., Charfi-Cheikrouha, F., Lorenzini, R., Vigne, J., Hartl, G. B., & Zachos, F.E. 2008. Phylogeography and founder effect of the endangered Corsican red deer (Cervus elaphus corsicanus). Biodiversity and Conservation 17: 659-673. Hedrick, P. W., Gutierrez-Espeleta, G. A., & Lee, R. N. 2001. Founder effect in an island population of bighorn sheep. Molecular Ecology 10: 851-857. Hundertmark, K. J. & Van Daele, L. J. 2010. Founder effect and bottleneck signatures in an introduced, insular population of elk. Conservation genetics 11: 139-147. Kolbe, J. J., Leal, M., Schoener, T. W., Spiller, D. A., & Losos, J. B. 2012. Founder Effects Persist Despite Adaptive Differentiation: A Field Experiment with Lizards. Science, 335: 1086-1089. Matute, D. R. 2013. The role of founder effects on the evolution of reproductive isolation. Journal of Evolutionary Biology 26: 2299-2311. Mayr, E. 1969. Bird Speciation in the tropics. Biological Journal of the Linnean Society 1: 1-17. Planes, S. & Lecaillon, G. 1998. Consequences of the founder effect in the genetic structure of introduced island coral reef fish populations. Biological Journal of the Linnean Society 63: 537-552. Welcome to Evolution 101! Evolution 101. Retrieved 21:24, October 28, 2014, from http://evolution.berkeley.edu/evosite/evo101/index.shtml

____________________________________________________________________________________________________________________________________ https://en.wikipedia.org/wiki/Founder_effect#cite_note-15 https://en.wikipedia.org/wiki/Founder_effect

Not all studies have been initiated after a volcanic eruption. Studies have been conducted when a species is reintroduced to an island where the initial population died off.

Few specific examples of studies are provided, especially in the way of animals and plants.

Whether the founder effect specifically refers to a change in the allele frequencies, or if it refers to a random generation of allele frequencies, which could be identical to the parent population, should be specified.

A four year long experiment studied the genetic diversity of seven founding populations of Anolis lizards, each on its own island, and determined that though there was evidence of natural selection, the differences in genetic variation between the islands was more relatable to the genetic variation of each of the island founders. Kolbe, J.J., Leal, M., Schoener, T.W., Spiller, D.A., & Losos, J.B. 2012. Founder Effects Persist Despite Adaptive Differentiation: A Field Experiment with Lizards. Science, 335: 1086-1089.

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I have chosen to complete my literature review on the topic of the founder effect, a method of genetic drift, with a slight focus on island ecology, so as to provide more information for the Wikipedia page. The founder effect can be defined as “the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population,” (Founder 2014). Depending on the genetic variation present in the new population, as well as on the climate of the new environment, a number of possibilities may occur. If the genetic variation in the new population is similar the variation present in the original population, little to no genetic drift may occur, if the environment is similar to the original. If, with analogous genetic variations, the new environment is not similar, genetic drift by natural selection is likely to occur upon the new population. However, the new population’s genetic variation may be anywhere from slightly to highly unrepresentative of the original population’s genetic variation. Over time, these new populations may incorporate mutations into the gene pool, speciate, or become so inbred that extinction is on the horizon. In respect to island ecology, as islands are all different shapes, sizes climates, and distances from the mainland, a wide variety of effects on the new populations are available. I will resort to the following papers to establish a review on the founder effect and its role in island ecology.

Founder effect. (2014, July 21). In Wikipedia, The Free Encyclopedia. Retrieved 16:02, September 14, 2014, from http://en.wikipedia.org/w/index.php?title=Founder_effect&oldid=617833733

Citation guide: https://owl.english.purdue.edu/owl/resource/560/10/ Article From a Database

1.) Hajji, G. M., Charfi-Cheikrouha, F., Lorenzini, R., Vigne, J., Hartl, G. B., & Zachos, F.E. (2008). Phylogeography and founder effect of the endangered Corsican red deer (Cervus elaphus corsicanus). Biodiversity and Conservation, 17, 659-673.

The authors are from universities and museums in France, Italy, Germany, and Tunisia. The main purpose of this study was to examine the relatedness of various regional deer species and determine the presence of a founder effect in a population. Twenty years prior to the study, a breeding group of 13 deer were brought to an island where the deer had gone extinct. This equates to three generations of deer, so all differences in genetic variation are the result of the random sample of deer that initiated the breeding program. At the time of this study, the “founder effect [had] resulted in incipient genetic differentiation through drift but [had] not led to a reduced genetic variability in the newly founded…population.” This will be useful in the review as it is an example of the early effects of the founder effect.

2.) Kolbe, J.J., Leal, M., Schoener, T.W., Spiller, D.A., & Losos, J.B. (2012). Founder Effects Persist Despite Adaptive Differentiation: A Field Experiment with Lizards. Science, 335, 1086-1089. The authors are from universities in the USA in biological or similar departments. This study observed the founder effect on seven islands that the authors populated with one pair of lizards each. After four years, adaptation to the new environments can be seen, but the authors argue that “even as this adaptive divergence has occurred; indeed, variation among experimental founder islands at the present time is better explained by initial phenotypes than by current environmental conditions.” Though the authors admit to supporting “the selectionist school,” I believe their work to be vital in establishing an unbiased review of founder effect experiments. They present data on a relatively long-term study on geno- and phenotypes and provide an insightful discussion of their result interpretations.

3.) Hundertmark, K.J. & Van Daele, L.J. (2010). Founder effect and bottleneck signatures in an introduced, insular population of elk. Conservation genetics, 11, 139-147.

The authors are from Alaska; one from a university and one from the state Division of Wildlife. This study looked at a founder effect population from 1929 when eight elk were relocated to a series of islands 1000+ km away from any other elk populations. “The founder effect imposed on Afognak elk due to a severe bottleneck has resulted in a significant reduction in allelic diversity and heterozygosity but not percent loci polymorphic compared with the source population from the Olympic Peninsula.” This study will be greatly utilized in this review as it is a long-term study with much data to draw from and incorporates other environmental factors including natural selection, the bottleneck effect.

4.) Hedrick, P.W., Gutierrez-Espeleta, G.A., & Lee, R.N. (2001). Founder effect in an island population of bighorn sheep. Molecular Ecology, 10, 851-857.

The authors are from biology departments in universities in Arizona and Costa Rica. This study focuses on the founder effect of 20 bighorn sheep introduced onto an island in 1975. “Because this population is being used as the source stock for populations throughout much of northern Mexico, it is fundamental for conservation planning to evaluate the genetic variation in this population to provide an indicator of its long-term fitness,” i.e. lots of data and analyses of this and other founding populations. However, their data is not entirely accurate, as some of the females were pregnant when relocated, meaning that the genetic diversity could be increased significantly by the genes of males not in the new population. However, the genetic variation within this new population did decrease, as is expected from a founder effect. As such, while this may not be the main paper, I think that including it will still serve to add viewpoints and ideas to the review.

5.) Planes, S. & Lecaillon, G. (1998). Consequences of the founder effect in the genetic structure of introduced island coral reef fish populations.

The authors are from a French university. “In the late 1950s and early 1960s the Bureau of Commercial Fisheries, at the request of the Division of Fish and Game of the State of Hawaii, undertook an introduction program which was supposed to bring new species of grouper and snapper for fisheries purposes. Between 1955 and 1961, 11 species of families Serranidae and Lutjanidae were introduced from several geographic locations. Among these species only three are known to have become established.” The authors study the founder effect in these three species and pose questions about the other eight. This paper is interesting in that fish are not prevented from escaping an island due to large amounts of water, and yet they are apparently unable to immigrate back to the original population. Additionally, the fact that only three of eleven species were able to acclimate to the new environment provides insight to failed founding populations.