Transcript PPT: Intro to Biodiversity and Diversity indices

Ecosystem Organization
• Organisms
Biosphere
– Made of cells
– Eukaryotic vs Prokaryotic
• Species
– Groups of organisms that resemble one
another in appearance, behavior, and genetic
make up
– Sexual vs Asexual reproduction
– Production of viable offspring in nature
– 1.5 million named; 10-14 million likely
Ecosystems
Communities
• Populations
– Genetic diversity
• Communities
• Ecosystems
• Biosphere
Populations
Organisms
Fig. 4.2, p. 66
Biodiversity 101
• Renewable resource—nature’s insurance policy against
disaster!
• Many forms all encompassed under the term
Biodiversity
– Species Diversity: the number and distribution of species in
a given community
– Genetic Diversity: genetic variability among individuals
within each species
– Ecological Diversity: the variety of different ecosystems
– Functional Diversity: ecosystem services such as matter
cycling, pollination, waste recycling, pest control,
purification etc needed for the survival of species and
communities
Loss of Biodiversity? Who cares?
• Gives us food, fibers, energy, raw materials, chemicals, medicines
• Essential to economy and our well-being!
• Every species here today
– Contains genetic information that represents thousands to
millions of years of adaptation to the earth’s changing
conditions
– Is the raw material for all future adaptations
• Loss of species reduces the availability of ecosystem services and
decreases the ability of species, communities, and ecosystems to
adapt.
• Biodiversity is nature’s insurance policy against disasters
• Diverse communities are generally less susceptible to perturbation
than similar but less diverse communities.
– When pollution is present or a human disturbance has occurred
in a community, biodiversity is typically lower than in an
undisturbed community.
What’s Happening to the Otters?
Types of Species
• Keystone
– Remember the Otters?
• Indicator
– Sentinels of environmental degradation
• Amphibians
• Benthic Macroinvertebrates
• Invasive/Exotic/Non-Native
– Gypsy moth, Zebra Mussel, Kudzu, etc
• Foundational
– Important in ecological succession
Species diversity is a measure of both the
species richness and species evenness of a
community
• Species Richness
– the number of species in a community Species
• Species Evenness
– the relative abundance of individuals within a species
• Species Dominance
– one or two species greatly outnumbering others (contrasts with
evenness)
• When comparing two communities, greater richness often
equals greater diversity. However, in communities with
equal numbers of richness, evenness or dominance must be
considered.
Measuring Diversity:
Species Richness (R)
The species richness is based solely on the number of
species found in the given area and does not reflect
the relative dominance of species.
Rs
Where:
s = the number of species
Measuring Diversity:
Shannon-Wiener Index (H)
This index is determined by both the number of species and the even
distribution of individuals among those species (relative dominance). It
indicates the degree of uncertainty of predicting the species of a given
individual picked at random from the community. In other words, if the
diversity is high, you have a poor chance of correctly predicting the
species of the next individual picked at random.
s
H   pi  ln  pi 
i 1
Where: pi (relative abundance) = ni/N
ni = number of individuals in species i
N = total number of individuals in all species
Measuring Diversity:
Species Evenness
Evenness (E) is a measure of how similar the abundance of different
species are. When there are similar proportions of all species then
evenness is one, but when the abundance are very dissimilar (some
rare and some common species) then the value increases.
H
E
ln R 
Where: H is the Shannon-Wiener index
R is species richness
Measuring Diversity:
Species Dominace
Dominance represents the most commonly occurring
species in a community as a percentage of the total
community
N max
N
Where: Nmax is the number of individuals in the most
commonly occurring species
N = total number of individuals in all species