PRACTICAL 6:

Measuring Genetic Diversity

Introduction

Genetic diversity is the variation at the level of individual genes. In a

population it means that the population contains most of the possible alleles for

each particular gene locus. More variation occurs, better the chance for at least

some of the individuals will have. An allelic variant that is suited for the new

environment will produce offspring with the variant and will reproduce and

continue the population into subsequent generations.

Genetic diversity is a level of biodiversity that refers to the total number of

genetic characteristics in the genetic makeup of a species. It is different from

genetic variability. Genetic diversity also refers to any variation in the nucleotides,

genes, chromosomes, or whole genomes of organisms. It represents the

heritable variation that exists between individuals within population, between

population within species and between species.

Genetic diversity enable all populations to adapt to new environmental

conditions and directly relevant to the chances of long term persistence of a

population. Therefore, it is importance for animal to have genetic variation in

order to live a better live and even surviving in the environments.

In this practical, as conservation agency which have enough funds to

purchase and protect four wetlands orchids. We needs to calculate the genetic

diversity in the wetlands in order to maintain and kept the most genetic variation

for future purposes. It also to make sure they have longer generation to live.

Objective:

- To measure the genetic diversity within populations

- To determine which populations to conserve

Procedure:

1. The allele frequencies in each population for the Fast – moving allele (p)

and the Slow – moving allele (q) is determine by counting number of

alleles for individuals in each population.

2. The genetic different between populations is measure. Hs is calculate by

multiplying 2pq for each population.

3. The expected heterozygosity of all populations is calculated by multiplying

2 x the average p x the average q.

4. The amount of local, within – population variation is calculated by using:

Fst = (Ht - Hs) / Ht.

5. The result is put into table below.

Result

Allele frequencies for Pterostylis isozymus

Fast allele p Slow allele q = 2 x p x q

Population 1 7/30 0.23 23/30 0.77 2 x 0.23 x 0.77 = 0.35

Population 2 18/30 0.60 12/30 0.40 0.48

Population 3 26/30 0.87 4/30 0.13 0.23

average 1.06/3

(Hs) 1.06/3 = 0.35

Allele frequencies for Pterostylis polyzymus

Fast allele p Slow allele q = 2 x p x q

Population 1 18/30 0.60 12/30 0.40 0.48

Population 2 16/30 0.53 14/30 0.47 0.50

Population 3 22/30 0.73 8/30 0.27 0.40

average 1.38/3

(Hs) 0.46

Expected heterozygosity (Ht) for Pterostylis isozymus

Fast allele p Slow allele q

population 1 7/30 0.23 23/30 0.77

population 2 18/30 0.60 12/30 0.40

population 3 26/30 0.87 4/30 0.13

average allele

frequency

1.70/3

=0.57

1.30/3

= 0.43

(Ht) = 2 x the average p x the average q = 2 x 0.57 x average q = 0.49

Expected heterozygosity (Ht) for Pterostylis polyzymus

Fast allele p Slow allele q

population 1 18/30 0.60 12/30 0.40

population 2 16/30 0.53 14/30 0.47

population 3 22/30 0.73 8/30 0.27

average allele

frequency

1.86/3

= 0.62

1.14/3

= 0.38

(Ht)= 2 x the average p x the average q = 0.47

Summary

Pterostylis isozymus

Fst = (Ht - Hs) / Ht = 0.49 – 0.35 / 0.49 = 0.29

Fst > 0.1 and indicates great divergence between populations of P.isozymus

Pterostylis polyzymus

Fst = (Ht - Hs) / Ht = 0.47 – 0.46 / 0.46 = 0.02

Fst > 0.01 and indicates some divergence between populations of

P..polyzymous

Populations of Pterostylis isozymus are more divergent than populations of

Pterostylis polyzymus. So, the populations of Pterostylis polyzymus are

genetically similar to each other.

Discussion

From the data, we noticed that, the Pterostylis isozymus had the Fst 0.29

which shown greater than 0.1, meanwhile Pterostylis polyzymus had the Fst

0.02 where it’s shown some or little divergence between the populations it

self. So the populations of each species are different from each other. In

order to have greater diversity of genetic within a population variation, the Fst

collected must be higher than 0.1 where it’s indicated great divergence

between populations.

To keep four of the wetland acquisition, I will choose the genetic which

shown greater diversity between the populations. I will use the fund to

conserve the wetland with great genetic diversity in order to have better

populations. So, I prefer to choose all the wetland from Pterostylis isozymus

because it’s shown the greater diversity within the population. But I only will

choose population 1 from the wetland Pterostylis polyzymous because it

shows the alleles having more different within the population. So as the

results, I will choose all the Pterostylis isozymus and pterostylis polyzymous

population 1 to be developed as an industrial site.

Others than the genetic diversity, the things that I must also to think about

are the endangered species and vulnerable species. It is because the species

are too little in the environment and it shall be kept so that it won’t to be

extinct from the ecosystem. Besides, I also would realize the quality of

environment of breeding site, population sizes and distribution into the

account. It is because when the environment had been harm by human

activity, the population might face bigger challenge toward the environment

and the ecosystem around it might have chance due to the activity done by

human. So the population can no longer sustain in the environment and as a

result it will die and cause the conservation to loss it funds.

Having a population with more genetic variation indicated that it is the

better population that can sustain in the environment. It is also shows the

population having better quality to adapt to the changes in its environment.

The most suitable wetland to be conserves and developed is the wetland

which shows the greater genetic diversity within the population.

Based on the reading of “Trouble in Paradise” by Eldridge (1998), the

scientists maximize the genetic diversity in the re–introduced population by

choosing animals from different islands. It is because the animals of the same

species but from different islands have highly diverse population created. The

animals from just one of the islands had an identical profile where there are

same and there are study shown island population tends to have less genetic

variation. When they choose animal from an island only, it may cause effect

when the animal get sick or strike by certain disease. Those animals might

come into extinct as all had the low genetic variation or having the same

genetic as they weak when against external treat.

References

Book Resources:

Campbell, N. A & Reece, J. B. (2005). Biology Seventh Edition. San Francisco: Pearson Education, Inc.

Miller (2007). Essential of Ecology Fourth Edition. Canada: Thomson

Internet Resources:

Wikipedia.(2008). Genetic Diversity. Retrieved October 6, 2008, from

Http://en.wikipedia.org/wiki/Genetic_diversity.

Paritsis, J. (2005). Genetic Diversity in Ecosystem Management. Retrieved

October 6, 2008, from

http://www.colorado.edu/geography/courses/geog_3412_s05/notes_37.htm

Harrison, I., Laverty, M., & Sterling, E. (2004). Genetic Diversity. Retrieved

October 6, 2008, from http://cnx.org/content/m12158/latest/