Lyme Disease

Borrelia burgdorferi

Species Area Curves

S = CAZ (log S) = Z (log A) + (log C)

From: Gotelli, N. J. 1995. A primer of ecology. Sunderland, MA: Sinauer Assoc. 1-206 p.

Species Loss Due to Deforestation

z = 0.15

z = 0.35

Log Forested Area

Log

# S

pec

ies

before

after

Based on empirical results, z typically between 0.15 and 0.35

Species Loss Due to Deforestation

9.05.0

78.05.015.0

35.0

Z

FZ

ZF

Z

ZFF

ZFF

Z

A

A

A

A

CA

CA

S

S

CAS

CAS Number of species before deforestation

Number of species after deforestation

Proportion of speciesafter deforestation

High and low estimate (I.e., 10-20%) of spp. extinctionsin tropics with 50% deforestation (expected in 30 years)

What About The Birds?95% “deforestation”, ~ 160 spp. of eastern forest birds, 4-5 extinctions.

What About The Birds?

• 160 x 0.050.25 = 75– 85 extinctions expected

• Only 50% of forest destroyed at any one time

• Only ~28 birds endemic to or breed only in east coast forests

• 28 x 0.50.25 = 23.5– 4-5 extinctions expected

Problems With Species-Area Approaches

• What is the “real” rate of deforestation?• How many species are endemic to an area.

– endemic means found only in that location

• What proportion of species are found in tropical forests

• Extinction rate as high as 27,000 spp. / year in tropical forests alone (Wilson, 1992)

Biodiversity at the Species Level

From Textbook, Primack

Extinctions Since1600

# Extinct

Red List (2000)

~ Total

Smith (1993)

Percent

Birds 128 9,500 1.4 %

Mammals 83 4,500 1.8 %

Total 211 14,000 1.5%

• ~ 65% of these extinctions since 1850• ~ 135 bird and mammal extinctions since 1850

Review: Background Rate

Are We in a Mass Extinction?

7

6

5

103.33

1

1011

1

104.6150000,14

135

yearsmillionspecies

extinction

yearsmillionspecies

extinction

yearsspecies

sextinction

Current extinction rate for birds and mammals ~ 65 to 200 times

higher than background rate

current extinction rate

background rate, high estimate

background rate, low estimate

What If Things Don’t Change?

3107.1100000,14

2313 yearsspecies

sextinction

Endangered, Threatened or Vulnerable (IUCN)1130 mammals + 1180 birds = 2313

Projected extinction rate ~ 1,700 to 5,100 times higher than background rate

What If Deforestation Continues?

What If Climate Change Continues?

What We’ve Finished

• EXTINCTIONS PAST AND PRESENT– Causes of extinction– Early mass extinctions– “Blitzkrieg” in the Pleistocene– Recent extinctions

What Can We Do?

• Given the impending extinction crisis, what can we can do?

Susceptibility to Extinction

• Species with only a few populations

• Species that need a large home range

• Animal species with large body size

• Small or declining populations

• Read others in book (Primack - Chapter 8)

Biology of Small Populations

• Population Dynamics of Small Populations

• Genetics of Small Populations

• Population Viability Assessment

Population Viability Analysis (PVA)

• The science of determining the probability that a population will persist for a given time

• We will use VORTEX

The “Population” in Conservation

• IUCN– Population is defined as the total number of

individuals of the taxon . . .– Subpopulations are defined as geographically

or otherwise distinct groups in the population between which there is little exchange (typically one successful migrant individual or gamete per year or less.

“Closed Population”

2nd Homework Assignment

• Identify a small animal population (< 1,000) and learn a little about it.– Full description on web page.– Do not use African Wild Dogs!

• Basis for term paper project.

• Due: Friday, March 2– Note HW1 due March 1