5 - Biological Diversity

BAT 311E: THE MANAGEMENT OF AQUATIC ECOSYSTEMS

BIOLOGICAL DIVERSITY

WHAT IS BIOLOGICAL DIVERSITY? VARIETY OF LIFE-FORMS AND ITS INTERACTIONS

OR NUMBER OF SPECIES/GENETIC TYPES IN AN AREA

BASIC CONCEPTS OF BIOLOGICAL DIVERSITY

1. GENETIC DIVERSITY A) TOTAL NO. OF GENETIC CHARACTERISTICS OF SPECIES/SUBSPECIES/GROUP OF SPECIES B) ANY VARIATION IN THE NUCLEOTIDES, GENES, CHROMOSOMES, OR WHOLE GENOMES OF ORGANISMS

BASIC CONCEPTS OF BIOLOGICAL DIVERSITY

2. HABITAT DIVERSITY: DIFFERENT KINDS OF HABITAT IN GIVEN AREA.

BASIC CONCEPTS OF BIOLOGICAL DIVERSITY

3. SPECIES DIVERSITY; •SPECIES RICHNESS – TOTAL ABUNDANCE •SPECIES EVENNESS – RELATIVE ABUNDANCE •SPECIES DOMINANCE – MOST ABUNDANT

HOW MANY SPECIES ON EARTH?

HOW MANY SPECIES ON EARTH?

1. 2. 3.

ONLY 1.5 MILLION SPECIES HAVE BEEN NAMED ESTIMATED SPECIES = BETWEEN 3 TO 100 MILLION. NEW SPECIES DICOVERED = EXTINCTION TO OTHER SPECIES

4. ABOUT 15,000 NEW SPECIES DESCRIBED EVERY YEAR 5. SOME 50% OF THE WORLD’S FLORA & FAUNA COULD BE ON A PATH TO EXTINCTION WITHIN A HUNDRED YEARS (STUART PIMM, 1999).

Microcebus lehilahytsara – found at Madagascar in 2005

Dodo (flightless bird) - Mauritius. Discovered 1598, extinct by 1681.

WHY ARE THERE SO MANY SPECIES?

1. INTERACTIONS BETWEEN SPECIES   

COMPETITION = NEGATIVE ON BOTH SYMBIOSIS = BENEFITS BOTH PREDATION – PARASITISM = BENEFIT ONE, BAD TO ANOTHER

2. COMPETITIVE EXCLUSION PRINCIPLE = COMPLETE COMPETITORS CANNOT COEXIST IN THE SAME HABITAT.

WHY ARE THERE SO MANY SPECIES? 3. ECOLOGICAL NICHE 

SPECIES THAT REQUIRE THE SAME RESOURCES CAN COEXIST BY UTILIZING THOSE RESOURCES UNDER DIFFERENT ENVIRONMENTAL CONDITIONS.

The ecological niche of an organism depends not only on where it lives but also on what it does. By analogy, it may be said that the habitat is the organism's "address", and the niche is its "profession", biologically speaking. Odum - Fundamentals of Ecology - W B Saunders 1959

MEASURING NICHE  HUTCHINSONIAN

NICHE =

DESCRIBE THE NICHE AS THE SET OF ALL ENVIRONMENTAL CONDITIONS UNDER WHICH A SPECIES CAN PERSIST AND CARRY OUT ITS LIFE FUNCTIONS

SYMBIOSIS  SYMBIOSIS =RELATIONSHIP BETWEEN 2 ORGANISMS THAT BENEFICIAL TO BOTH AND ENHANCES EACH CHANCES OF PERSISTING. OBLIGATE SYMBIONTS = SYMBIONT THAT COULD NOT SURVIVE WITHOUT THE OTHER. SAVING SPECIES FROM EXTINCTION = SAVE THE HABITATS, NICHE AND ALSO ITS SYMBIONTS.

PREDATION AND PARASITISM 

PREDATION = AN ORGANISM (PREDATOR) FEEDS ON OTHER LIVE ORGANISMS (PREY)



PARASITISM = AN ORGANISM (PARASITE) LIVES ON, IN OR WITHIN ANOTHER (HOST) & DEPENDS ON IT FOR EXISTENCE – NO USEFUL OR HARM.



PREDATION AND PARASITISM INCREASE DIVERSITY – COMPETITIVE EXCLUSION PRINCIPLE.

ENVIRONMENTAL FACTORS THAT INFLUENCE DIVERSITY

Some Major Factors that Increase and Decrease Biological Diversity

A. Factors that tend to increase diversity 1. A physical diverse habitat 2. Moderate amounts of disturbance ( such as fire or storm in a forest or a sudden flow of water from a storm into a pond) 3. A variation in environmental conditions (temperature, precipitation, nutrient supply, etc) 4. High diversity at one trophic level increases the diversity another trophic level. (Many kinds of trees provide habitats for many kinds of birds and insects.) 5. An environment highly modified by life (eg. a rich organic soil) 6. Middle stages of succession 7. Evolution

Some Major Factors that Increase and Decrease Biological Diversity

B. Factors that tend to decrease diversity 1. Environmental stress 2. Extreme environments (conditions near the limit of what living things can withstand) 3. A severe limitation in the supply of essential resource 4. Extreme amount of disturbance 5. Recent introduction of exotic species (species from other area) 6. Geographic isolation (being on a real or ecological island)

The End….

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