Environment and Ecology: Introduction to Biodiversity

Dr. Roman Saini gives an Intro to Biodiversity.

-Biodiversity refers to the degree of variation of life.
-The term was popularized by Edward Wilson
- It may also be used to refer to the totality of genes, species and ecosystems of a region.

Levels of Biodiversity

Earth is not only unique for the presence of life but also the biodiversity. These may be categorized as:

1)Genetic Diversity

-Genetic diversity encompasses all the genes, its various alleles (different types of genes) and its variations in a single species over its distributional range (total genetic pool). For this reason, it is not advisable to marry relatives since the genetic pool among the relatives is small thus the chances of inbreeding depression increases.
-For instance, India has thousands of rice and mango strains.

2) Species Diversity

-The effective number of different species in a region. This kind of biodiversity is further subdivided into two classifications as listed below:
(i) Species richness- a simple count of species.
(ii) Species evenness- it quantifies the equalness of the abundances of the species.

3) Ecological diversity

-Is the number of different biomes and ecosystems in a region. In the world today, there are over 12 countries which qualify as being mega diverse.
-For instance, there is more biodiversity in LOTIC (running freshwater e.g. a river) than in a LENTIC (stagnant fresh water e.g. a pond) ecosystem.

The Bio-Sphere/Eco-Sphere

-It refers to the sum total of all the ecosystems on planet earth.
-It is the spot wherein the atmosphere, lithosphere and hydrosphere interact and give rise to life.
-Life can be found everywhere on earth with some notable exceptions:

(i) Extremes of height ( >8000m above Mean Sea Level [MSL])
(ii) Extremes of poles (both north and south)
(iii) Deep trenches e.g. the Mariana
(iv) Very high in atmosphere (above the stratosphere)

Definition of Terms

-Bioprospecting: It is the process of discovery and commercialization of new products based on biological resources.
It incorporates the indigenous knowledge in focusing screening efforts for bio-active compounds.
-Bio-piracy: The exploitative appropriation of indigenous forms of knowledge by big commercial firms, without permission from and with little or no compensation or recognition to the indigenous people themselves.

Biodiversity Hotspot (Norman Myers)

-This is a Bio-geographic region with a significant reservoir of biodiversity that is under human threat. There are a total of 25 such places.
-For a region to be termed as a hotspot, it must meet the following conditions:
(i) High species diversity
(ii) High degree of endemism
(iii) Rapid loss of biodiversity

Exact Criteria for Qualification

-It must contain at least 0.5% or 1500 species of vascular plants as endemics
-It must have lost 70% or more of its primary vegetation.
For instance, India has 2 hotspots: Indo-Burma and Western Ghats (including Sri Lanka).

Mega Biodiverse Countries

-These are a group of countries that have the majority of the earth's species.
-They are mainly found in the tropical and subtropical regions. They include:
(i) The Americas: Brazil, Colombia, Ecuador, Peru, Mexico, USA
(ii) South East Asia: Papua New Guinea, Philippines, India, China
(iii) Others include: Australia, Madagascar, DRC, and South Africa.

Number of Species

-The total number of eukaryotic species is 8.74m, of which only 20% have been discovered and on record.
-This number is affected by specialization and extinction.
-Animals account for over 70% of this number, with insects numbering over 50%.
-For vertebrates, the distribution is:
(i) 50% fish
(ii) 32% birds and reptiles
(iii) 9% mammals
(iv) 11% amphibians.

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