1. Habitat Degradation & Loss
Photo of Chicago (lower right) from Wikipedia

2. Species-Area Curves A very consistent pattern of
organismal distribution
No. species
Area
van der Werff, Henk Species number, area and habitat diversity in the Galapagos Islands. Vegetatio 54:
For a great read on research into evolutionary processes on Galapagos try the Pulitzer Prize winner: “The Beak of the Finch.”
Data for Galapagos plants from van der Werff (1983) Vegetatio

3. Log10(y) = Log10(30.4) + (0.31 • Log10(x))
Species-Area Curves
y = 30.4 • x0.31
R² = 0.78
No. species
Log10(y) = Log10(30.4 • x0.31)
Log10(y) = Log10(30.4) + (0.31 • Log10(x))
Area
ylog = (0.31 • xlog) + 1.5
R² = 0.78
van der Werff, Henk Species number, area and habitat diversity in the Galapagos Islands. Vegetatio 54:
Log10 (No. species)
Data for Galapagos plants from van der Werff (1983) Vegetatio
Log10 (Area)

4. Species-Area Curves Barro Colorado Island
Map from Photo by Christian Ziegler from

5. Species-Area Curves No. species Area Log10 (No. species) Log10 (Area)
Although these data are from an island, notice that in this case the species-area curve comes from comparing quadrats of different sizes within a contiguous patch of forest (as opposed to comparing islands of differing sizes).
Oddly enough, for BCI, the best fit curvilinear line is actually a natural logarithmic one. Even so, here are the equations for the figures in the slide:
Untransformed  y = x ; R² =
Log(10) transformed  yLog = xLog ; R² =
Log10 (No. species)
Data from the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama
Log10 (Area)

6. Relative-Abundance Distributions
Whittaker rank-abundance curve
Log10 (No. individuals)
Data from BCI 50-ha Forest Dynamics Plot, Panama; 229,069 individual trees of 300 species; most common species nHYBAPR=36,081; several rarest species nRARE=1.
Dominance-diversity (or rank-abundance) diagram, after: Robert H. Whittaker (1975) Communities and Ecosystems, 2nd ed. MacMillan, New York, NY.
Rank
Most species are rare!
Data from the 50-ha Forest Dynamics Plot on Barro Colorado Island, Panama

7. Geographic distribution
Seven Forms of Rarity
Most species are rare, but rarity can be defined in various ways
Habitat specificity
Broad
Restricted
Broad
Restricted
Somewhere
large
Common
Rare
(no examples?)
Rare
Local population size
Everywhere
small
Deborah Rabinowitz, Sara Cairns & Theresa Dillon Seven forms of rarity and their frequency in the flora of the British Isles; in Michael Soulé, editor, Conservation Biology, Sinauer.
Note that Wide + Broad + Somewhere_large = Common, so the 7 forms of rarity include representative organisms, except for Wide + Restricted + Everywhere_small.
Wide
Narrow
Geographic distribution
See: Rabinowitz et al. (1986) in Soulé, ed., Conservation Biology – based on British flora

8. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
Image of extinct Hawai’i ’Ō’ō (Moho nobilis) from Wikipedia

9. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
E.g., Hawaii’s native bird species
Half of the remaining species went extinct soon after Captain James Cook arrived
(in 1778)
Half went extinct soon after the Polynesians arrived
(in ~ 300 A.D. / C.E.)
Image of extinct Hawai’i ’Ō’ō (Moho nobilis) from Wikipedia

10. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
In a closed population (i.e., no immigration or emigration) of size N,
the change in population size for a change in time, where B = births, and D = deaths, is:
Think of these as the “BIDE factors”: birth, immigration, death, emigration. ∆N
= B - D ∆t
Remember the “BIDE factors”: birth, immigration, death & emigration

11. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
In a closed population (i.e., no immigration or emigration) of size N,
the change in population size for a change in time, where b = per capita birth rate, and d = per capita death rate, is:
Think of these as the “BIDE factors”: birth, immigration, death, emigration. ∆N
= b(N) – d(N) ∆t ∆N
= (b-d)(N) ∆t

12. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
Substitute r for (b-d), where
r = per capita growth rate: ∆N
= r(N) ∆t
If r>0, N grows; if r<0, N declines; if r=0, N does not change

13. Rare species are especially vulnerable
Small populations are especially prone to extinction from both deterministic and stochastic causes
Example, r = –0.5 :
Population A Population B
NA,t = NB,t = 10 ∆N
Nt+1 = Nt + ∆t
NA,t+1 = 500
NB,t+1 = 5

14. Rare species are especially vulnerable Genetic stochasticity
Small populations are especially prone to extinction from both deterministic and stochastic causes
Deterministic  r < 0
Genetic stochasticity
Demographic stochasticity  individual variability of r (e.g., variance)
Environmental stochasticity  temporal fluctuations of r (e.g., change in mean)
Catastrophes
Genetic stochasticity mostly involves genetic drift, founder effects, etc.
Note that demographic stochasticity differs from environmental stochasticity in that demographic stochasticity concerns the variance around r, whereas environmental stochasticity concerns the temporal variation in mean r.
For more info. on deterministic and stochastic causes of population change, see:
M. S. Boyce. Population viability analysis. Annual Review of Ecology and Systematics 23:
Also see: Kent Holsinger’s Conservation Biology Web site, especially re “Biology of Small Populations”
Deterministic threats cause r<0.
Stochastic threats cause variability in r: demographic stochasticity (or uncertainty) concerns chance events that affect indiv. mort. and reprod., whereas environmental stochasticity (or uncertainty) concerns temporal fluctuations in prob. of mort. or reprod. experienced simultaneously by all indivs.

15. Demographic & Environmental Stochasticity Demographic Stochasticity
Each student is a sexually reproducing, hermaphroditic,
out-crossing annual plant.
Arrange the plants into small sub-populations (2-3 plants/pop.).
In the first growing season (generation), each plant mates
(if there is at least 1 other individual in the population)
and produces 2 offspring.
Offspring have a 50% chance of surviving to the next season.
flip a coin for each offspring;
“head” = lives, “tail” = dies.
Note that average r = 0; each parent adds 2 births to the population and on average subtracts 2 deaths [self & 1 offspring – since 50% of offspring live and 50% die] prior to the next generation.
In the first growing season (generation), each student mates (if there is at least 1 other individual in the population) and produces 2 offspring. Offspring have a 50% chance of surviving to the next season. Flip a coin for each offspring; “head” = lives, “tail” = dies. Note that average r = 0; each parent adds 2 births to the population and on average subtracts 2 deaths [self & 1 offspring – since 50% of offspring live and 50% die] prior to the next generation.
In a large pop. (e.g., whole class), heads and tails average out to give r=0 (no change in pop. size). When class is sub-divided into small sub-populations (e.g., 2 individuals each with no migration), some will have less than 2 live individuals after the coins are flipped to determine survivorship to the next growing season (the next generation).
It would be especially instructive to compare the population trajectory for the class as a whole for the same number of generations as there are groups of 2 in the class (since some of the groups of 2 will perish in 1 generation [and the overall meta-population is likely to decline], whereas for the whole class as a single panmictic populatin many generations can be expected before extinction would become likely).
Remember also that even this does not take into account individual variability in r itself; as advocated by Dan Doak and Bill Morris one should use a distribution of values for r.

16. Habitat Destruction, Loss, Degradation…
At least 83% of the Earth’s land surface has been
transformed by human activities (Sanderson et al. 2002)
About 60% of Earth’s ecosystems are considered
degraded or unsustainably used (Millennium Ecosystem Assessment 2005)
98% of U.S. streams and rivers have been fragmented
(see next lecture) by dams (Benke 1990)
Benke, A. C A perspective on America’s vanishing streams. J. N. Am. Benthol. Soc. 9:77-88.
Millennium Ecosystem Assessment World Resources Institute, Washington, D.C.
Sanderson et al The human footprint and the last of the wild. BioScience 52:

17. Habitat Destruction, Loss, Degradation…
Habitat degradation – impacts that affect many, but not all species;
some of which may be temporary
Habitat destruction & loss – impacts that affect nearly all species;
time scale for recovery is very long
How do humans destroy & degrade habitats & ecosystems?
E.g., agricultural activities, extraction activities, certain kinds of development
These are often considered to be the most important direct threats to
biodiversity, since they eliminate species, reduce population sizes,
and reduce performance of individuals

18. Habitat Destruction, Loss, Degradation…
Loss of terrestrial coastal habitats in Louisiana
Land loss 1932 to 2000 is historical. Land loss projections to 2050 depend on what we do about it; these projections are based on no change in anthropogenic causes.
Image of Louisiana land loss (historical & projected; ) from 18

19. Habitat Destruction, Loss, Degradation…
Degradation of marine and coastal habitats in Louisiana
Website:
Oil rig explosion and subsequent oil spill off Louisiana’s coast – summer 2010.
Deepwater Horizon – drilling rig explosion on April 20, 2010
Map from 19

20. Habitat Destruction, Loss, Degradation…
Anthropogenic degradation of oceans
Benjamin S. Halpern, Shaun Walbridge, Kimberly A. Selkoe, Carrie V. Kappel, Fiorenza Micheli, Caterina D'Agrosa, John F. Bruno, Kenneth S. Casey, Colin Ebert, Helen E. Fox, Rod Fujita, Dennis Heinemann, Hunter S. Lenihan, Elizabeth M. P. Madin, Matthew T. Perry, Elizabeth R. Selig, Mark Spalding, Robert Steneck, and Reg Watson (2008) A Global Map of Human Impact on Marine Ecosystems. Science 319: 948 – 952.
Halpern et al. (2008) Science; see

21. Habitat Destruction, Loss, Degradation…
Loss of ice from polar ice cap
From – “Arctic perennial sea ice has been decreasing at a rate of 9% per decade. The first image shows the minimum sea ice concentration for the year 1979, and the second image shows the minimum sea ice concentration in The data used to create these images and the following animation were collected by the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSMI). Credit: NASA.”
Minimum sea ice concentration; 9% decline per decade
Images from 21

22. Pollution is a Form of Habitat Degradation
Light pollution
Air pollution & acid rain
Solid waste & plastics
Chemical pollution (e.g., DDT, endocrine disruptors)

23. Pollution is a Form of Habitat Degradation
Rachel Carson (1907 – 1964)
Silent Spring (1962) – motivated creation of the U.S. Environmental Protection Agency
Her book, Silent Spring (1962), motivated a reversal in federal pesticide policy (e.g., a ban on DDT) and motivated the grassroots environmental movement of the 1960s and 1970s that led to the creation of the Environmental Protection Agency.
Photo from Wikipedia

24. Pollution is a Form of Habitat Degradation
Theo Colborn (b. 1927)
Theo Colborn, Dianne Dumanoski & John P. Meyers (1997) Our Stolen Future: How We Are Threatening Our Fertility, Intelligence and Survival
Theo Colborn, Dianne Dumanoski, John P. Meyers (1997) Our Stolen Future: How We Are Threatening Our Fertility, Intelligence and Survival.
This book especially raised public awareness of anthropogenic pollutant chemicals as endocrine disruptors in the environment.
Image from

25. Pollution is a Form of Habitat Degradation
Light pollution
Air pollution & acid rain
Solid waste & plastics
Chemical pollution (e.g., DDT, endocrine disruptors)
Excessive nitrogen inputs
Eutrophication
Etc…

26. Pollution is a Form of Habitat Degradation
Excessive nitrogen inputs & eutrophication
Image from

27. Pollution is a Form of Habitat Degradation
Excessive nitrogen inputs & eutrophication
contribute to coastal hypoxia (i.e., the “dead zone” phenomenon) every summer off Louisiana’s coast
Image from

28. Biodiversity Hotspots
Usually defined by species richness, endemism & threats
These hotspots of biodiversity cover only ~1.5% of the Earth’s land;
if they were destroyed ~1/3 of Earth’s species would go extinct
Norman Myers, Russell A. Mittermeier, Cristina G. Mittermeier, Gustavo A. B. da Fonseca & Jennifer Kent Biodiversity hotspots for
conservation priorities. Nature 403:
Quote from Myers et al. (2000):
“As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth.”
Figure from Myers et al. (2000, Nature)

29. Biodiversity Hotspots
Usually defined by species richness, endemism & threats
There have been several attempts to define hotspots around the world. I like the one in this figure, since it reminds us of the human connection to the hotspot locations. The map is from the Food and Agriculture Organization of the United Nations (FAO), which is a specialized agency of the United Nations that leads international efforts to defeat hunger.
Map from

30. local losses aggregate to produce the global crisis.
Biodiversity Crisis
Whether or not habitat degradation or loss occurs in a biodiversity hotspot, any resulting biodiversity losses contribute to the global phenomenon, since
local losses aggregate to produce the global crisis.
Image of oiled pelicans on June 3, 2010 from the Gulf of Mexico from Wikipedia