Transcript BIOLOGY 154: ECOLOGY and ENVIRONMENTAL ISSUES

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. coli
Lichen (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