Da dang di truyen Lĩnh vực học thuật di truyền học quần thể bao gồm nhiều giả thiết và lý thuyết liên quan tới đa dạng di truyền.

Đa dạng di truyền là tổng số các đặc điểm di truyền trong thành phần di truyền của một loài. Nó khác với biến dị di truyền, thuật ngữ dùng để mô tả xu hướng biến đổi của các đặc điểm di truyền. Đa dạng di truyền là một cách để các quần thể có thể thích nghi được với môi trường sống thay đổi. Với nhiều biến đổi hơn, một số cá thể trong một quần thể sẽ có cơ hội cao hơn trong việc sở hữu những biến dị alen phù hợp với môi trường.

GENETIC DIVERSITY

Ngon T.TRUONG Molecular Biology Laboratory

Content:

Introduction: Biodiversity

World wildlife fund (1998) defines :

- all living organism on the planet

- genes they contain

- ecosystems they reside in

Biodiversity

Definition

Genetic Diversity

 GD refers to the variation at the level of individual

genes (polymorphism), and provides a mechanism for

population to adapt to their ever-changing environment

 The more variation, the better the chance that at least

some of the individuals will have an allelic variant being

suited for the new environment

Fig 1 Genetic Diversity in human being

Fig 3 Genetic Diversity in mungbean seeds

(Vigna sp.)

Fig 4 Genetic Diversity in hot pepper fruits

(Capsicum sp.)

Genes

Chromosomes Changed Diversity

Why?

How?

Where?

How importance?

Adaptation Evolution

Mechanism

Centers of origin

Mechanism of Genetic Diversity

 Jumping Gene: Barbara Mc Clintock, 1951 (video.)

 Recombination : meiosis

 Variations :

gene mutation : deletion, insertion (animation)

chromosomes variation:

- in number : euploidy, aneuploidy

- in morphological : translocation, inversion

Crossing over

(Meiosis)

Duplication

Deletion

Inversion

Reciprocal

Translocation

Ring Chromosome

Effects of genetic variation

Vavilov, 1951

1/ Benefits :

- Agriculture : enhancing soil fertility, controlling epidemy,

providing food safety

2/ Importance :

cross

P = G + E PHENOTYPE

GENOTYPE

ENVIRONMENT

Traits:

Qualitative

Quantitative

DNA

Methods for identifying GD

Genetic Diversity – measures

Source: Lee’s course

5 basic methods to determine which alleles are

present at a given locus All techniques use

electrophoresis

Polymorphic bands by RAPD marker

Source: Ngon & Nelson 2001

M 1 5 10 15 21

Polymorphic band by SSR marker

Source : Ngon & Nelson 2001

M 1 5 10 15 20 M

Diversity indices

 Shannon

 Simpson

 McIntosh

 Brillouin

 Gleason

 Margalet

 Menhinick

 Standard deviation (SD)

Keywords & formulas

Richness : number of species/1 area unit

Abundance : number of individual in certain species

Shannon

Simpson







 S

i

i

p H





i pi

D

1

2

1

Similarity indices

Simple Matching Coefficient

Jaccard index

Sorensen index

Ochiai,Kendall, Morisita, Horn indexes

Pearson correlation index

Similarity percentage : Whittaker

Similarity index : Bray Curtis

Risks causing Genetic erosion :

conditions, and living environment;

 Changing in cropping system;

 Destroying living environment;

 Market pressure;

 Natural calamity, or catastrophe by human;

 Setting up unapproriate agricultural policy

Methods for enhancing genetic diversity:

 genetic resource : introduce, making cross, mutation,

wild species, transgenics

 cropping system: rotation, intercrop, overlapping crop

 ecological systems :

crops + fish feeding

crops + shrimp feeding

crops + living organism feeding in flooding regions

BioPro software : tool for analyzing biodiversity

Analyse descriptor parameters : mean, variance, SD etc

Analyze biodiversity indexes : Shannon, Simpson, etc

Analyse genetic diversity, species diversity

Cluster analysis (CA)

Principal Component Analysis (PCA)

Correspondence Analysis

Can interface with other softwares EXCEL,ACCESS

Why? Living Organisms Adaptation Evolution

to occur? Genes : jumping; mutation

Variation in chromosomes: number; morphology

to identify? Phenotype evaluation

Genotype analysis: Protein, DNA markers

to analyse? Softwares : common; professional (Biopro)

How

A gene mutationis a situation where a new allele arises

through a change in the DNA code

A chromosome variationis a situation where a segment of

chromosome, a whole chromosome, or a set of chromosomes

changes

Definition of genetic variations

Transposable elementsare DNA sequences which have the

References

1 Heal, G et al Genetic Diversity and Interdependent Crop Choices in Agriculture In:

Genetic diversity in Agriculture.

2 http://www.rewhc.org/biomeasures.shtml.

3 Brown, T., T Hodgkin 2003 Maintaining Plant Genetic Diversity in

Agroecosystems IPGRI’s report.

4 Hawtin, G 2002 Biotechnolgy in the maintenance and use of Crop Genetic

Diversity IPGRI.

5 Fedoroff, N 2001 How jumping genes were discovered http://structbio.nature.com.

6 NBII homepage Biodiversity-Genetic Diversity

7 Sivaprakash, K.R et al 2004 Genetic diversity of black gram (Vigna mungo)

landraces as evaluated by AFLP markers Current Science, vol.86.

8 Baranek, M et al 2002 Evaluation of Genetic Diversity in 19 Glycine max (L.)

Merr Accessions included in the Czech National Collection of Soybean Genotypes

Czech J Genet Plant Breed 38: 69-74.

9 Falco, S.D., and C Perrings 2003 Crop Genetic Diversity, Productivity and Stability

of Agroecosystems A theoretical and Empirical investigation Scottish Journ of

Political Economy Vol 50 N.2.

10 Brown-Guerdira, G.L., J.A Thompson, R.L Nelson, and M.L Warburton 2000

Evaluation of Genetic Diversity of Soybean Introductions and North American

Ancestor Using RAPD and SSR markers.

THANK YOU VERY MUCH !!