Biodiversity

Let’s start with…what is diversity?

Which community has the highest richness?

Which community has the highest diversity?

Why?

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Shannon-Weaver Diversity Index

Shannon-Weiner Diversity Index

Shannon Index

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Most commonly used diversity measure:

plot 101 trt 1Common name Scientific name COVER area p lnp plnp

black cherry Prunus serotina 2 18 0.026785714 -3.61989 -0.09696black raspberry Rubus occidentalis 1 2 0.00297619 -5.81711 -0.01731daisy fleabane Erigeron annuus 2 18 0.026785714 -3.61989 -0.09696deer tongue Dichantheliem clandestinum 1 2 0.00297619 -5.81711 -0.01731dotted smartweed Polygonum punctatum 2 18 0.026785714 -3.61989 -0.09696elderberry Sambucus pubens 2 18 0.026785714 -3.61989 -0.09696frost grape Vitis vulpina 2 18 0.026785714 -3.61989 -0.09696hackberry Celtis 1 2 0.00297619 -5.81711 -0.01731horseweed Conzya 1 2 0.00297619 -5.81711 -0.01731iron weed Cyanthillium 1 2 0.00297619 -5.81711 -0.01731jumpseed Polygonum virginianum 2 18 0.026785714 -3.61989 -0.09696nimble will Muhlenbergia scheebri 3 180 0.267857143 -1.3173 -0.35285pokeweed Phytolacca americana 1 2 0.00297619 -5.81711 -0.01731purple wintercreeper Euonymus fortunei 1 2 0.00297619 -5.81711 -0.01731red mulberry Morus rubra 3 180 0.267857143 -1.3173 -0.35285rough avens Geum laciniatum 1 2 0.00297619 -5.81711 -0.01731sedges Carex  virginia creeper Parthenocissus quinquefolia 3 180 0.267857143 -1.3173 -0.35285white ash Fraxinus americana 1 2 0.00297619 -5.81711 -0.01731white clover Trifolium repens 1 2 0.00297619 -5.81711 -0.01731white mulberry Morus alba 1 2 0.00297619 -5.81711 -0.01731yellow wood sorrel Oxalis europaea 1 2 0.00297619 -5.81711 -0.01731

672 1 -95.4766 -1.84807

Figure from The Diversity of Life, EO Wilson, University of Harvard Press

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).

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

http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

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 HypothesisProductivity-Diversity Hypothesis

Intermediate Disturbance Hypothesis

Intermediate Disturbance Hypothesis

http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

Under what condition is diversity maximized?

Productivity-Diversity Hypothesis

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Productivity

http://www.smithsonianmag.com/science-nature/victory-at-sea.html#

Question: Does diversity matter?

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