An Analysis of the Observed Heterozygosity of Lake Trout

An analysis of the observed heterozygosity of Lake Trout communitys from ternion lakes irritate, Eagle, and Loughborough, inferred from microsatellite transmitted constitutions. Abstract This study was undertaken in order to compare the heterozygosity of three Lake Trout creations at various loci. Samples of twenty-five Lake Trout were collected from three lakes Devil, Eagle and Loughborough, all three of which are situated north of Kingston, Ontario. An autoradiograph was used to analyze the genotypes of the individuals at sixsome different loci of microsatellites, which are repeat sequences in the DNA that are neutral and do not code for proteins.This data was used to compare the inherited diverseness of the three different trout populations. Numerical values for observed heterozygosity (Ho) were then generated using the data and the Doh heterozygosity calculator. The results have indicated that the think up heterozygosity in respect of Devil Lake trout was importantly greater than that of the trout in Eagle Lake (p=2. 89E-7) as well as that of Loughborough Lake (p=1. 44E-19). Further more than, the mean heterozygosity for Eagle Lake trout was significantly greater than that of Loughborough Lake (p=2. 2E-6). This may be due to the fact that essential selection acts as a force to face inbreeding to eliminate harmful genes causing low heterozygosity in a population. In addition, human and natural personal effects occurring in the lakes, for example, fishing and water temperature may cause differences in heterozygosity. Understanding and using these findings may help with sustaining fish populations. Introduction Heterozygosity is the measure of the genetic transmutation in a population at a particular gene locus.Genetic variation indoors a population is important in maintaining or change magnitude the fittingness of members in the population and ultimately the survival of the species. Fitness describes the capability of an individual species o f a certain genotype to reproduce, and is usually equal to the proportion of the individuals genes in all the genes of the next generation. A positive correlation was found between the heterozygosity at the loci and the fitness (survival and maturation) of the fish, suggesting that heterozygosity is advantageous (Pujolar et al. 005). A heterozygote advantage describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. An individuals fitness is manifested through its phenotype, and the phenotype may be affected by some(prenominal) genes and environmental characteristics. One such characteristic that was observed to possibly have an effect on levels of heterozygosity in a population was the area in which the population lives. In an experiment conducted by Rowe et al. 1999) the heterozygosity of various populations of Natterjack Toads (Bufo calamita) found in several areas were compared, ultim ately discovering a dismantle heterozygosity in a population that is disjointed from opposites. Volckaert and Zouros (1989) conducted a study to measure genetic diversity levels in scallops (Placopecten magellanicus) and discovered levels of heterozygosity to be highest as age increased. Ferguson (1990) found similar information that affects diversity among rainbow trout (Oncorhynchus mykiss) and cogitate that heterozygosity levels were proven to have a direct relationship between the sex, size and age of the fish.There are many factors that may affect the genetic diversity of a population. In particular, various events and environmental characteristics may affect the genetic diversity of Lake Trout. One factor may include fishing. This activity may cause the population of the fish to decrease at an unstable rate, thus this study will be undertaken to determine the many factors that may contri exclusivelye influences to the genetic diversity of Lake Trout in three lakes Devil, E agle and Loughborough Lake.Using six microsatellite loci from 25 Lake Trout from all three lakes, observed heterozygosity values that act as an indicator for genetic diversity, will be obtained and analyzed. This data can be further used by analyzing and providing additional information about the influences of certain characteristics on population genetics. Results Figure 1 illustrates that the lake with the greatest observed heterozygosity is Devil Lake. It was determined that the observed heterozygosity of Devil Lake is significantly greater than the observed heterozygosity of Loughborough Lake (p=1. 4E-19). The sample size for all 3 lakes was 25 Lake Trout. Figure 1. The graph illustrates the mean observed heterozygosity of the three lakes. The error bars represent standard deviation. Discussion The conducted experiment involving heterozygosity of Lake Trout from Devil, Eagle and Loughborough Lake shows that there are significant differences between the three lakes. Devil Lake ha d the highest mean heterozygosity within its population, Eagle Lake heterozygosity was found to be in the middle and Loughborough Lake with the lowest.It was determined that the observed heterozygosity of Devil Lake was significantly greater than the observed heterozygosity of Loughborough Lake (p=1. 44E-19). The difference in the data sets outcomes may be explained by a number of factors, such as natural selection, fishing and restocking the lake, and lake temperatures. All these factors may cause diversity in heterozygosity. The goal of an organism is to reproduce and pass their genes on to the next generation allowing the species to survive.The passing on of genetic material can be achieved through inbreeding or outbreeding. Inbreeding is the breeding amongst family or self outbreeding is the breeding with members of the same species that are not closely related. It may be believed that inbreeding is not good for a population with such opinions being based on having seen the resu lt of inbreeding in valet de chambre. Inbreeding as well as outbreeding, however, has both advantages and disadvantages. One advantage of inbreeding is its ability to dispirit the expression of recessive alleles (Ellstrand and Elam 1993).In a population with a damaging recessive allele, an individual may not seek to mate with anyone who potentially carries or expresses that allele. In this example the population might inbreed to decrease the heterozygosity in an attempt to remove the harmful gene. Mating within the family- when it is apparent that the family does not carry the detrimental allele, is more ideal in an evolutional prospective than putting the survival of that population at risk.In regards to Ellstrand and Elams study, this situation could occur in the Lake Trout from Loughborough causing the Lake Trout to have a lower mean heterozygosity. This Lake Trout population could be purging undesired alleles from its gene pool. One can conclude that not only does genetics hav e an effect on heterozygosity, but humans do as well. Another factor that may cause a loss of genetic diversity is fishing pressures. Smith et al (1990) suggested that fishing activities which concentrate on spawning populations differentially remove the older and more heterozygous individuals from the virgin stock.Previously stated, levels of heterozygosity are higher as age increases (Volckaert and Zouros 1989). Due to fishing, the descend of Lake Trout may decrease and there would be less fish. To fix the amounts of fish in the lakes, humans restock the lakes with hatchery fish (fish that are grown by humans and released into the wild). Evans et al. (1991) found that the human harvested fish tend to have lower genetic variation and actually decrease the fitness and survival of the native species. Loughborough Lake has the biggest population but the lowest heterozygosity.Compared to Eagle Lake and Devil Lake, most people from the Loughborough Lake area receive their income from f ishing (Ontario Ministry of Natural Resources 1970). Excessive fishing depletes the amount of fish and creates the perceived deprivation to continually restock the lake with fish. The practice of restocking the lake with hatchery fish may result in the large population of Lake Trout which would in turn decrease the heterozygosity of Loughborough Lake. There are other factors that may contribute to increase levels of heterozygosity in fish.One such characteristic that may increase levels of heterozygosity in fish is fluctuations in water temperature. Zimmerman and capital of Virginia (1981) found that extremely variable thermal regions demand for greater fitness. The fittest of fish are more heterozygous because they are able to survive in different temperatures. In Zimmerman and Richmonds experiment, the greatest temperature fluctuation was 7C, with the highest heterozygosity level of 49%. This trend may prove that the greater the temperature fluctuation, the greater the heterozyg osity of a population living within the waters.The temperature fluctuations of the three lakes are Devil Lake at 31F, Eagle Lake at 21F, and Loughborough Lake at 7F (Ontario Ministry of Natural Resources 1970). These numbers correlate with the data by showing that Devil Lake with the highest temperature fluctuation has the greatest heterozygosity, whereas Loughborough Lake with the lowest temperature fluctuation has the lowest heterozygosity. The mean heterozygosity of Lake Trout from Devil Lake was significantly greater than that of trout from Eagle Lake, which was greater than that of Loughborough Lake.Potential reasons for genetic diversity may be caused by natural selection acting as a force to cause inbreeding to eliminate harmful genes, fishing in the lakes which then require the lakes to be restocked with hatchery fish, and thermal fluctuations that cause differences in heterozygosity. Further research and experiments specifically looking in depth at effects that causes genet ic diversity should provide greater insight into why the heterozygosity in populations varies. Literature Cited Ellstrand N. , Elam R. 1993.Population genetic consequences of small population size implications of plant conservation. Annual Review of bionomical Systems. 24 217-242. Evans D. , Casselman J. , Wilcox C. 1991. Effects of Exploitation, deviation of Nursery Habitat, and Stocking on the Dynamics and Productivity of Lake Trout Populations in Ontario Lakes. Ontario Ministry of Natural Resources. 193 1-3 Ferguson M. 1990. Enzyme Heterozygosity and growth in Rainbow Trout Genetic and Physiological Explanations. The Genetical ball club of Great Britain. 8 115-122. Ontario Ministry of Natural Resources. 1970. Map of Eagle Lake. Map of Loughborough Lake. Map of Devil Lake. Queens University Map and Air Photo Library. 613. Pujolar J. , Maes G. , Vancoillie C. , Volckaert F. 2005. Growth tread Correlates to Individual Heterozygosity in the European Eel, Anguilla Anguilla L. Evol ution. 59 189-199. Rowe G. , Beebee T. , Burke T. 1999. Microsatellite heterozygosity, fitness and demography in natterjack toads Bufo calamita. Animal Conservation. 2 85-92. Smith P. Francis R. , McVeagh M. 1991. Loss of Genetic Diversity due to Fishing Pressure. Fisheries Research. 10 309-316. Volckaert F. , Zouros E. 1989. Allozyme and physiological variation in the scallop Placopecten magellanicus and a general model for the effects of heterozygosity on fitness in marine molluscs. Marine Biology. 103 51-61 Zimmerman G. , Richmond M. 1981. Increased Heterozygosity at the Mdh-B Locus in Fish Inhabiting a Rapidly Fluctuating Thermal Environment. American Fisheries Society. cx 410-416