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CHAPTER ONE

INTRODUCTION

1.1   BACKGROUND TO THE STUDY

Population Genetics of aquatic species focuses on describing the genetic differences between populations of fish, between the individuals within the same population and between fish in aquaculture. For example, a brown trout from one part of Nigeria does usually not have the same genetic fingerprint (DNA profile) as a brown trout from another part of Nigeria, just as the North Sea cod does not have the same genetic fingerprint as the Baltic Sea cod.  The genetic variation of contemporary fish populations is the result of evolutionary processes, reflecting both geographical separations of populations over thousands of years and genetic adaptation to local conditions. The genetic differences can be analyzed and described using modern DNA technologies, providing important information on the factors influencing the distribution and dynamics of fish populations. They also provide us with a technical tool for tracing individual fish and fish products back to the sea-areas or aquaculture plants from where they originated.  

Population genetic analyses are used to determine the population composition of fish catches in order to avoid over exploitation of small and vulnerable fish populations. The analyses may also be used to control illegal fishing by testing whether landed fish and fish products originate from species and stocks which can legally be caught.  Genetic monitoring also plays an important role in planning the long-term management of fish resources. The work is carried out by comparing DNA from contemporary fish samples with DNA analyses of samples from historical time series.  This is done by comparing DNA from fish scales and otoliths sampled more than 100 years ago, providing insight into how wild populations have responded to stocking, fishing and environmental change. Thus, inferences from such experiment can be used to guide management in order to preserve the genetic variation, resulting in healthy and productive fish populations that can be exploited sustainably. Population genetics is the study of genetic variation among species, individuals and populations; fundamentally, it shows that distribution of genetic variability is affected by evolutionary forces of mutation, migration, selection, and random genetic drift (Hansen, 2003).

Assessing genetic diversity in aquaculture stocks or wild fish populations is crucial for effective management, interpretation, and understanding and of fish populations or stocks. Many characteristics and methods have been used to analyze stock structure in fish populations; they include ecological, tagging, parasite distribution, physiological and behavioural traits, morphometrics and meristics, calcified structures, cytogenetics, immunogenetics and blood pigments (Samaradivakara et al., 2012). Unfortunately, environmental variables often affect the relationship between genes and their phenotypic expression significantly. Thus, the population geneticists mainly focused on Mendelian traits in species widely used in laboratory studies or on available pure breeds of few species (Hallerman, 2003). The development of DNA amplification using the PCR (Polymerase Chain Reaction) technique opened up the possibility of examining genetic changes in fish populations over the past years (Ferguson et al., 1995).

Capacity building also referred to as capacity development, is a conceptual approach to development that focuses on understanding the obstacles that inhibit people, governments, international organizations and non-governmental organizations from realizing their development goals while enhancing the abilities that will allow them to achieve measurable and sustainable results. Due to the slow adoption of modern technologies by developing countries occasioned by poor economic status, research into applied population genetics of aquatic species in Nigeria is at its lowest helm. However, there is need for rapid capacity building and technology transfer in applied population genetics of aquatic species to increase productivity and for the creation of new and better breeds of aquatic animals in Nigeria.

1.2   STATEMENT OF THE PROBLEM    

Molecular genetic markers used in applied population genetics are powerful tools to detect genetic uniqueness of individuals, populations or species (Doveri et al., 2008). Modern sequence based marker systems for genetic analysis such as Single Nucleotide Polymorphisms (SNPs) and Simple Sequence Repeats (SSRs) are now predominantly used in applied population genetics of aquatic species (Duran et al. 2009). However, Microsatellites have become the marker of choice for application in fish population genetic studies (Beckmann and Soller, 1990). They have multiple alleles which are highly polymorphic among individuals. The polymorphism obtained with microsatellite markers has provided powerful information to be considered in the management of fish stocks (Alam and Islam, 2005), population analysis and biodiversity conservation. In addition; microsatellites have a wide distribution in the genome and can be efficiently identified, which is essential in studies about genetic variability of populations (Boris et al., 2011). High cost of developing species-specific markers has been the main challenge of microsatellite markers in Nigeria. Now, this can be alleviated with effective capacity building and technology transfer.

1.3   OBJECTIVES OF THE STUDY

The following are the objectives of this study:

1.  To examine the benefits of applied population genetics of aquatic species in Nigeria.

2.  To examine the level of practice of applied population genetics of aquatic species in Nigeria.

3.  To examine the benefits accruable form capacity building and technology transfer in applied population genetics of aquatic species in Nigeria.

1.4   RESEARCH QUESTIONS

1.  What are the benefits of applied population genetics of aquatic species in Nigeria?

2.  What is the level of practice of applied population genetics of aquatic species in Nigeria?

3.  What are the benefits accruable form capacity building and technology transfer in applied population genetics of aquatic species in Nigeria?

1.5   SIGNIFICANCE OF THE STUDY

The following are the significance of this study:

1.  The outcome of this study will expose the benefits accruable form capacity building and technology transfer in applied population genetics of aquatic species in Nigeria ranging from production of new and better breeds of aquatic animals to the increased productivity that will boost the economy.

2.  This research will be a contribution to the body of literature in the area of the effect of personality trait on student’s academic performance, thereby constituting the empirical literature for future research in the subject area.

1.6   SCOPE/LIMITATIONS OF THE STUDY

This study will cover various technology used in applied population genetics of aquatic species all over the world including microsatellite. It will also cover the benefits accruable form capacity building and technology transfer in applied population genetics of aquatic species.

LIMITATION OF STUDY

Financial constraint- Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).  
Time constraint- The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.

REFERENCES

Alam S and Islam S (2005). Population genetic structure of Catla catla (Hamilton) revealed by microsatellite DNA markers. Aquaculture 246: 151-160.

Beckmann, J.S and Soller, M (1990). Toward a unified approach to genetic mapping of eukaryotes based on sequence tagged micro satellite sites. Bio/Technology 8, 930– 932

Boris Brinez, Xenia Caraballo O, Marcel Salazar V (2011). Genetic diversity of six populations of red hybrid tilapia, using Microsatellite genetic Markers. Rev.MVZ Cordoba 16 (2): 2491-2498.

Doveri S, Lee D, Maheswaran M, Powell W (2008). Molecular markers: History, features and applications. In Principles and Practices of Plant Genomics, Volume 1, C.K.a.A.G. Abbott, ed. (Enfield, USA: Science Publishers), pp. 23-68.

Duran, C., Nikki,A.,David,E and Jacqueline B (2009).Molecular Genetic Markers: Discovery, Applications,Data stoarage and visualization.Current Bionformatics 11,37 -41.

Ferguson, A., Taggart, J.B., Prodohl, P.A., McMeel, O.,Thompson, C., Stone, C., McGinnity, P. and Hynes, R.A (1995). The application of molecular markers to the study and conservation of fish populations,with special reference to Salmo.Journal of Fish Biology,47:103-126.

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