BIOLOGY 157: LIFE SCIENCE: AN

ENVIRONMENTAL APPROACH (Biodiversity, Niche, Species-Species Interactions)

CONSERVATION BIOLOGY, BIODIVERSITY AND

ENDANGERED SPECIES

• CONSERVATION BIOLOGY

• a relatively new multidisciplinary science which deals with the maintenance of ecosystems and their biodiversity

• studies human effects on biodiversity and tries to develop practical ways of preserving biodiversity and ecological integrity

BIODIVERSITY

THREE MAIN COMPONENTS

1) Species Diversity the number of species in an area

2) Genetic Diversity the number of genetic strains within a species

3) Ecological Diversity refers to the complexity and richness of a

community (# of niches, # of trophic levels, # of ecological processes)

HOW MANY SPECIES?

• Approx. 1.5 million already described

• 3 million is a minimum number

• some estimate 30 to 100 million (probably a gross overestimate)

• 5 to 10 million (a more reasonable estimate)

• new species discovered all the time, especially in understudied areas such as rainforests, soil, deep sea and in incompletely studied groups such as fungi, insects, mites, and nematode worms

REASONS FOR PRESERVING BIODIVERSITY

• Aesthetics / Recreation / Health

• Cultural-Historical Knowledge

• Scientific Knowledge (Should this be a separate listing?)

• Economic

• Ecosystem Stability

WHAT CAUSES SPECIES TO BECOME ENDANGERED / THREATENED / EXTINCT

• Over Exploitation (too much hunting, harvesting, collecting, etc.)

• Toxics in the ecosystem

• Habitat Alteration / Destruction / Fragmentation (farming, grazing, logging, introduction of

EXOTIC species (Dutch Elm Disease, Zebra Mussels, Japanese Beetle, Water Hyacinth)

ENDEMIC SPECIES ?

EXOTIC SPECIES ?

HOW TO SAVE / PRESERVE THE BIOTA?

• need to treat the biota as a ‘COMMONS’

• need more centralization / coordination of preservation and management efforts

• must have suitable habitat of sufficient size Island Biogeography

• suitable habitats must be assisted in their recovery or constructed from scratch

• Germplasm Banks - Zoos and Botanical Gardens - True Genetic Banks › Seed Banks › Sperm, Ova, and Embryo Banks › DNA Banks

THE FATE OF SPECIES

• It is the ultimate fate of all species to become extinct.

• There is a limit to the number of species / genetic strains that can be preserved.

• Species may have attributes that make them more OR less likely to become threatened / endangered / extinct.Examples:

THE ECOLOGICAL NICHE• We have all probably used the term ‘niche’ before.• What does it mean?

• DEFINITION:• A multidimensional concept which defines a species

“place” in a community in relation to other species.

• It is more than just the physical place (‘address’) where a species lives, it also includes its role (‘occupation / lifestyle’).

• Thus the Ecological Niche is a multidimensional concept which includes where an organism lives AND also includes what it does, how it does it, when it does it, etc. It is its total role in the ecosystem.

TYPE OF NICHE

• Fundamental or Hypothetical

the total range of physical, chemical and biological factors a species can utilize / survive if there are no other species affecting it

• Realized or Actual

that portion of the fundamental niche that a species actually uses.

Species never live under ‘perfect’ conditions but where an ‘acceptable’ ECOLOGIC SUM of conditions exists.

NICHE EXCLUSION PRINCIPLE(= Competitive Exclusion Principle)

(= Gause’s Law)• DEFINITION: In normal communities two

species cannot occupy the same niche for any length of time.

• It follows logically that no two species can coexist if they need all the same things in the same place, at the same time, etc.)

• The greater the degree of niche overlap, the greater the competition for scarce resources AND the more likely one species will eliminate the other.

GAUSE & PARAMECIUM(too much niche overlap)

LIMITING NICHE OVERLAP (I)

LIMITING NICHE OVERLAP (II)

LIMITING NICHE OVERLAP (III)

INTERSPECIFIC INTERACTIONS

• Neutral Interactions none of the interacting species is affected by the

others Is this really possible???????????

• Positive Interactions at least one of the interacting species is benefited

and the other(s) is (are) not harmed

• Negative Interactions at least one of the interacting species is harmed

during the interaction

Positive Interactions (I)

• Commensalism one species is benefited and the other(s) is (are) not

affected without continuous contact : Vulture / Predator with continuous contact: Turtle / Alga

• Protocooperation both species are benefited BUT the relationship is

NOT obligatory without continuous contact: Squirrel / Oak Tree with continuous contact: some Mycorrhizae (a

fungus / plant root relationship)

Positive Interactions (II)

• Mutualism both species are benefited AND the relationship IS

obligatory

without continuous contact:many Pollinator / Plant relationships

with continuous contact: Termites / Protozoans

Humans / E. coliLichen (alga / fungus)?most Mycorrhizae (fungus / plant root relationships)

NEGATIVE INTERACTIONS (I)

• Competition both species are harmed during the interaction

• Imperfect neither species is eliminated but one or both are

reduced in number (some niche overlap) Pontin’s work with 2 species of ants of the genus Lasius

• Perfect one species is eliminated (too much niche overlap) Gause’s work with 2 species of Paramecium

NEGATIVE INTERACTIONS (II)

• Predation one is helped (fed) --- one is harmed (eaten); a direct attack in which one species (the predator)

benefits by killing and eating another (the prey) Wolf / Deer Are both helped??????

• Parasitism one is helped (fed) --- one is harmed (weakened); a direct attack in which the parasite benefits by

taking small quantities of materials from its host over an extended period of time and generally does not kill the host.

Tape Worm / Human