Biodiversity
Let’s start with…what is diversity?
Which community has the
highest richness?
Which community has the
highest diversity?
Why?
Most commonly used diversity measure:
s
H    pi ln pi
i 1
Shannon-Weaver Diversity Index
aka
Shannon-Weiner Diversity Index
aka
Shannon Index
plot 101
Common name
black cherry
black raspberry
daisy fleabane
deer tongue
dotted smartweed
elderberry
frost grape
hackberry
horseweed
iron weed
jumpseed
nimble will
pokeweed
purple wintercreeper
red mulberry
rough avens
sedges
virginia creeper
white ash
white clover
white mulberry
yellow wood sorrel
trt 1
Scientific name
COVER area p
lnp
plnp
Prunus serotina
2
18 0.026785714 -3.61989 -0.09696
Rubus occidentalis
1
2 0.00297619 -5.81711 -0.01731
Erigeron annuus
2
18 0.026785714 -3.61989 -0.09696
Dichantheliem clandestinum
1
2 0.00297619 -5.81711 -0.01731
Polygonum punctatum
2
18 0.026785714 -3.61989 -0.09696
Sambucus pubens
2
18 0.026785714 -3.61989 -0.09696
Vitis vulpina
2
18 0.026785714 -3.61989 -0.09696
Celtis
1
2 0.00297619 -5.81711 -0.01731
Conzya
1
2 0.00297619 -5.81711 -0.01731
Cyanthillium
1
2 0.00297619 -5.81711 -0.01731
Polygonum virginianum
2
18 0.026785714 -3.61989 -0.09696
Muhlenbergia scheebri
3 180 0.267857143 -1.3173 -0.35285
Phytolacca americana
1
2 0.00297619 -5.81711 -0.01731
Euonymus fortunei
1
2 0.00297619 -5.81711 -0.01731
Morus rubra
3 180 0.267857143 -1.3173 -0.35285
Geum laciniatum
1
2 0.00297619 -5.81711 -0.01731
Carex
Parthenocissus quinquefolia
3 180 0.267857143 -1.3173 -0.35285
Fraxinus americana
1
2 0.00297619 -5.81711 -0.01731
Trifolium repens
1
2 0.00297619 -5.81711 -0.01731
Morus alba
1
2 0.00297619 -5.81711 -0.01731
Oxalis europaea
1
2 0.00297619 -5.81711 -0.01731
672
1 -95.4766 -1.84807
According to National Science Foundation
Currently ~ 2 Million identified species
Earth could contain from 8.7 ± 1.3 million
Scientists estimate that up to 140,000 species are lost
to extinction on a yearly basis; this current extinction
rate is 100 to 1000 times the rate of species loss prior
to human existence (Pimm et al. 1995).
Figure from The Diversity of Life, EO Wilson,
University of Harvard Press
Rainforests:
6% of Earth’s surface- 50% of the species
In the Amazon- 170,000 species of plant
(68% of the known total- 250,000)
- In 5 acres- 300 species of tree.
- 30% of all bird species
http://www.exploratorium.edu/frogs/rainforest/index.html
Pinning down exact numbers is nearly impossible, but most experts
agree that we are losing upwards of 80,000 acres of tropical
rainforest daily, and significantly degrading another 80,000 acres
every day on top of that. Along with this loss and degradation, we
are losing some 135 plant, animal and insect species every day—or
some 50,000 species a year—as the forests fall.
Coral Reefs the “rainforests of the
ocean”
The Great Barrier Reef, the world's largest
system of coral reefs, covers 349,000 square
kilometers and occupying only one-tenth of one
percent of the ocean surface, supports:
-nearly 8 percent (1,500) of the world's fish
species,
more than 700 species of coral.
-over 4,000 species of mollusks.
-252 species of birds nest and breed on the
coral cays, five species of turtles live on the
reef, and several species of whales and
dolphins are associated with it.
-Tropical (almost totally).
Now, some theories of biodiversity…
OK…so why are these two systems, the MOST diverse in the world?
There is a latitudinal gradient in species diversity in marine &
terrestrial systems. Includes many different genera and
species!
Hillebrand, H. 2004. On the generality of the latitudinal diversity gradient.
The American Naturalist 163:192-211.
More solar energy = greater species richness…but why?
Hypotheses?
Ecological filters dictate ultimate community composition
Under what condition is diversity maximized?
Species-Area Relationship
http://www.smithsonianmag.com/science-nature/victory-at-sea.html#
Under what condition is diversity maximized?
Two important hypotheses:
Intermediate Disturbance Hypothesis
Productivity-Diversity Hypothesis
http://www.smithsonianmag.com/science-nature/victory-at-sea.html#
Intermediate Disturbance Hypothesis
Intermediate Disturbance Hypothesis
Under what condition is diversity maximized?
Productivity-Diversity Hypothesis
http://www.smithsonianmag.com/science-nature/victory-at-sea.html#
Diversity
Productivity
Question: Does diversity matter?
http://www.smithsonianmag.com/science-nature/victory-at-sea.html#
Why are some species rare and others abundant?
General trends in the reproductive
biology of rare plants.
-Very often they produce few fruits,
that have very minimal dispersal
distances.
-Are self-incompatible.
-Have specific pollinator
relationships that create
vulnerability. (lose the pollinator, no
more reproduction)
-Are commonly pollen limited
because there are not enough
individuals around.
-Seed set is uncommon and weak.
-Some years, no seeds at all.
Why are some species rare and others abundant?
General trends in the
reproductive biology of rare
animals.
-Not as clear general trends.
-Mostly “K-selected species”
-Bats for instance, have one or
two babies a year max.
Biodiversity