Welcome to Biogeography
Transcript of Welcome to Biogeography
![Page 1: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/1.jpg)
Island Biogeography
![Page 2: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/2.jpg)
Class Outline
• Basic concepts and history
• Equilibrium Theory of Island Biogeography
• Violations to the assumptions
• Research
• Additional patterns of insular biota
![Page 3: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/3.jpg)
Why islands?
Defined boundaries
![Page 4: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/4.jpg)
Unique biotas attracted biologists for centuries
Why islands?
![Page 5: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/5.jpg)
Isolated
Why islands?
![Page 6: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/6.jpg)
Numerous
Why islands?
![Page 7: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/7.jpg)
But, characteristics vary
Why islands?
![Page 8: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/8.jpg)
Not only oceanic islands… virtual islands
![Page 9: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/9.jpg)
Wallace Darwin
![Page 10: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/10.jpg)
Historical Background
• Past several centuries - uniqueness of islands
• Pre mid-1900s
“There are only two possible hypotheses to account for the stocking of an oceanic island with plants from a continent: either seeds were carried across the oceans by currents, or the winds, or birds, or similar agencies; or the islands once formed part of the continent, and the plans spread over intermediate land that has since disappeared.” Hooker, 1866.
– Dispersal or vicariance?
– Historical, evolutionary, static theory of islands
![Page 11: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/11.jpg)
Historical Background
• Past several centuries - uniqueness of islands
• Pre mid-1900s
– Dispersal or vicariance?
– Static theory of islands
• 1967 - MacArthur and Wilson’s ETIB
– Radical shift in thought
– Dynamic, process-based
theory based
![Page 12: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/12.jpg)
Wilson: “Here’s another piece in the puzzle. I’ve found that as new ant species spread out from Asia and Australia onto the islands between them, such as New Guinea and Fiji, they eliminate other ones that settles there earlier….So there seems to be a balance of Nature down to the level of the species.”
MacArthur: “Yes, a species equilibrium. It looks as though each island can hold just so many species, so if one species colonizes the island, an older resident has to go extinct. Let’s treat the whole thing as if it were a physical process. Think of an island as filling up with species from an empty state up to the limit.”
![Page 13: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/13.jpg)
Robert MacArthur
• Doctoral dissertation, Yale (1958) on competition and coexistence of warblers
• Hypothesis testing
![Page 14: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/14.jpg)
Edward O. Wilson
• BS, MS, PhD Harvard
• Origin and relationships of ants on islands in East Indies and South Pacific
• Biogeography and animal behavior
• Conservation of biodiversity
![Page 15: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/15.jpg)
– Species richness increases with island area
– Species richness decreases with isolation
– Recognized underlying relationships
– Proposed unifying theory
![Page 16: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/16.jpg)
Underlying processes
• Effect of island area and isolation on species richness mediated by immigration & extinction
• Species richness on islands a function of the balance between immigration and extinction
![Page 17: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/17.jpg)
Immigration
• Function of the distance from the mainland (source of potentially colonizing species)
• Immigration decreases with isolation
• Successful colonization decreases with species richness, due to increased competition (i.e. fewer available niches)
![Page 18: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/18.jpg)
Extinction
• Function of island area
• Smaller islands have higher extinction rates
• Smaller islands provide fewer resources & lower habitat heterogeneity
• Smaller islands support fewer individuals within a species more vulnerable to extinction
![Page 19: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/19.jpg)
Island Patterns
• Species-area relationship
• Species-isolation relationship
• Species turnover
![Page 20: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/20.jpg)
Species-Area relationship
-Area influences extinction rates -Non-linear
![Page 21: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/21.jpg)
Olaf Arrhenius
• Proposed mathematical generalization of pattern (1920, 1921)
• S = cAz
– S = species richness
– c = constant
– A = island area
– z = slope of relationship between log (S) and log (A)
![Page 22: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/22.jpg)
Why does species richness increase with area?
![Page 23: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/23.jpg)
Will a small island have more, fewer, or the equal number of species as a comparable area on a continent? Why?
![Page 24: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/24.jpg)
Will a small island have more, fewer or the equal number of species as a comparable area on a continent? Why?
Remember, S = cAz
Which area has the
higher z?
![Page 25: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/25.jpg)
Species-Isolation relationship
![Page 26: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/26.jpg)
Species-Isolation relationship
Distance from source habitat
Spec
ies
rich
nes
s
Influences immigration rates
![Page 27: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/27.jpg)
What are some ways in which “effective isolation” can mean more than distance from a source?
Distance from source habitat
Spec
ies
rich
nes
s
Influences immigration rates
![Page 28: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/28.jpg)
Species Turnover
![Page 29: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/29.jpg)
Species Turnover
• Species composition is constantly changing on islands
• However, species richness is relatively constant (dynamic equilibrium)
![Page 30: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/30.jpg)
Equilibrium Theory of Island Biogeography (ETIB)
MacArthur Wilson
![Page 31: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/31.jpg)
Equilibrium Theory of Island Biogeography (ETIB)
MacArthur Wilson
Species richness on an island represents a dynamic equilibrium
controlled by the rate of immigration of new species and the rate
of extinction of previously established species.
![Page 32: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/32.jpg)
Species richness influences on immigration & extinction
• Successful immigration (colonization) decreases with increased species richness (S)
– Limited pool of species to colonize an area
– As S increases, fewer new species to immigrate
• Extinction risk increases with increased species richness
– Fixed area has finite resources
– As S increases, so does competition (intra &inter)
• New species may colonize at any S, but may drive established species to extinction
![Page 33: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/33.jpg)
Let’s combine the species-area and the species-isolation relationships
“Dynamic equilibrium”
What happens if #
of species strays
from equilibrium
value (e.g.
disturbance)?
![Page 34: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/34.jpg)
What makes this dynamic?
• # of species may reach a stable equilibrium, but…
the composition of the community is dynamic and changing even if the number of species is relatively stable about some equilibrium point
turnover
![Page 35: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/35.jpg)
Let’s combine the species-area and the species-isolation relationships
![Page 36: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/36.jpg)
If two islands of equal size are disturbed, will the near or far island return to equilibrium faster?
![Page 37: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/37.jpg)
For two islands of equal distance from mainland, does a large or small island have higher turnover?
![Page 38: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/38.jpg)
Strengths and Weaknesses
PROS
• Simple graphical presentationelegant representation of complex ideas
• Hypothesis to be tested!
• Produces clear hypotheses and indicates the kind of data needed to test hypotheses
CONS
• Too simple? factors other than isolation and area will affect species richness
![Page 39: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/39.jpg)
Criticisms of the Theory
• Interspecific differences and interactions among species not accounted for
• Interdependence of immigration and extinction
– Immigration may be affected by area
– Extinction may be affected by isolation
• Biogeographically meaningful measures of isolation (i.e. distance too simplistic)
– Isolation not purely a function of distance
![Page 40: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/40.jpg)
Criticisms of the Theory
• Biogeographically meaningful measures of island area.
– Area not necessarily reflective of carrying capacity
• Importance of speciation
• Disturbance in ecological to geological time scales.
– Disturbances may prevent equilibrium conditions
![Page 41: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/41.jpg)
Key Assumptions
1. Extinction is only influenced by island size
2. Immigration is only influenced by island isolation
3. Continual turnover occurs
![Page 42: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/42.jpg)
Violations of the assumptions
• Rescue effect
• Target area effect
• Small island effect
![Page 43: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/43.jpg)
Study: Arthopods on individual thistles in desert shrublands (Brown and Kodric-Brown 1977)
• Some results supported ETIB:
1. Plant size, isolation, biodiversity
2. Dynamic equilibrium
3. Isolation, immigration rates
4. Turnover, plant size
![Page 44: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/44.jpg)
Consistent with ETIB?
Turnover should be lower on large islands – YES
Turnover should be lower on far islands – NO
![Page 45: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/45.jpg)
Rescue effect
• Immigrants may rescue populations from extinction
• Violates the 1st assumption:
– Extinction is also influenced by isolation
![Page 46: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/46.jpg)
Draw different extinction curves for near and far islands
Rescue effect
![Page 47: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/47.jpg)
Target Area Effect
• Colonization rates of shrews on small islands in a Finnish lake (Hanski and Peltonen 1988)
• Results: Colonization rates increased with island area
![Page 48: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/48.jpg)
Target Area Effect
• Study: Tracked movements of terrestrial mammals across ice-covered St Lawrence River of NA in winter (Lomolino 1990)
• Immigration rates correlated with island area
![Page 49: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/49.jpg)
Target Area Effect
• Study: water-dispersed plant propagules and islands in Great Barrier Reef, Australia (Buckley and Knedlhans (1986)
• Results:
![Page 50: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/50.jpg)
Target area effect
• Larger islands are more likely to be encountered by immigrants
• Larger islands will get more immigrants than smaller islands
• Violates the 2nd assumption:
– Immigration is also influenced by island size
![Page 51: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/51.jpg)
Draw different colonization curves for large and small islands
Target effect
![Page 52: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/52.jpg)
Small island effect
Species richness appears to be independent of island size for very small islands
![Page 53: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/53.jpg)
Testing the ETIB theory
Several studies documented the theory supporting the generality of the pattern
![Page 54: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/54.jpg)
Diamond (1969)
• Avifauana of Channel Islands
• Census ~1917 (Howell 1917)
• Census 1968 (Diamond 1969)
• Sources of error
![Page 55: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/55.jpg)
Diamond (1969)
Turnover
LF<SF~LN<SN
![Page 56: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/56.jpg)
Criticisms
• Effects from human actions
• Migratory/nomadic species
![Page 57: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/57.jpg)
Lack (1976)
• Birds in Jamaica over 200 years
• Results: relative stasis
– 65 species
– 2 extinctions
– 1 colonization
![Page 58: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/58.jpg)
1883 eruption of Krakatoa
![Page 59: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/59.jpg)
Krakatau Studies
• Repeat surveys
• Bird populations by 1920
• Plant populations
• Problems with comparing surveys
• Difficult conditions: birds vs plants
![Page 60: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/60.jpg)
Caveats
• Inaccurate measure of immigration
• Surveys not standardized
![Page 61: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/61.jpg)
Colonization after eruption
• Plants
– Oceanic dispersed
– Wind dispersed
– Animal dispersed
• Differences due to
dispersal mode
• 1920: Shift from open
vegetation to forest
![Page 62: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/62.jpg)
Dynamic equilibrium?
![Page 63: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/63.jpg)
Anthropogenic Islands
• 1911-1914 - Chagres River dammed to create
Panama Canal and Gatun Lake
• Form a hypothesis of what will happen to the
biodiversity on the newly formed islands
![Page 64: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/64.jpg)
Anthropogenic Islands
Barro Colorado – largest island (1600 ha)
• 1970/80s - 45 bird species disappeared
• 1994-1996 – rate of loss declined
![Page 65: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/65.jpg)
Anthropogenic Islands
Caroni Valley, Venezuela
• 1986 - flooded creating Lago Guri and hundreds
of islands of different sizes
• Relaxation of bird species immediately after flood
• Area reduced, isolation increased
• Rate of loss (i.e. turnover) highest in small
islands
![Page 66: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/66.jpg)
Anthropogenic Islands
Caroni Valley, Venezuela
• Extinctions were selective
• Predator decline
• Herbivore abundance
• Ecological consequence?
![Page 67: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/67.jpg)
ETIB?
• Studies from Panama and Venezuela support aspects of ETIB
• Extinctions and immigrations are continuous
• Extinction rates are fastest at early stages following loss in area
and increase in isolation
• Turnover highest on small islands
Turnover on islands of Lake Gatun
![Page 68: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/68.jpg)
Turnover on islands of Lake Gatun
ETIB?
• Studies from Panama and Venezuela support aspects of ETIB
• Extinctions and immigrations are continuous
• Extinction rates are fastest at early stages following loss in area
and increase in isolation
• Turnover highest on small islands
• Turnover highest further from mainland…but, some species
rescued
![Page 69: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/69.jpg)
Experimental Testing
• First rigorous experimental testing (Simberloff and Wilson 1969)
• Methods: elimination of arthropods from small mangrove islands of different sizes & distance to neighbors in Florida Keys
• Monitored species composition and biodiveristy over 1 year
![Page 70: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/70.jpg)
Results
Returned to original species richness
High turnover observed
Couldn’t test effects statistically due to low sample size
Why is E1 different?
![Page 71: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/71.jpg)
Stages of dynamic equilibria?
![Page 72: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/72.jpg)
Nonequilibrium systems
• Is equilibrium always achieved?
• ETIB helped identify non-equilibrium systems
– Climate, landscapes, sea levels
![Page 73: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/73.jpg)
Mountain tops in SW NA (Brown 1971, 1978)
– Glacial maximum: cool, wet – forest species
– Glacial recession: warm, dry – desert species
– Created mountain range “islands”
3000 m
![Page 74: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/74.jpg)
![Page 75: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/75.jpg)
Patterns of non-volant mammal diversity in mountain islands?
![Page 76: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/76.jpg)
WHY?
• Wetter Pleistocene climate allowed wide dispersal of species
• End of Pleistocene and desertification left only islands of mesic habitat
• Forest mammals unable to disperse
• Area effects on extinction rates
• Relaxation of supersaturated
community; non-equilibrium
• Creation of “Pleistocene relicts”
![Page 77: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/77.jpg)
Postglacial Landbridge
• Sea levels rise 120m post-Pleistocene & created islands in coastal regions
• New Guinea – influence of past connections to mainland on bird composition (Diamond 1972)
– Continental islands vs oceanic islands
– Higher diversity on continental islands
– Non-equlibrium due to historical effects
![Page 78: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/78.jpg)
Post-Pleistocene dynamics of freshwater faunas
• Pleistocene – cooler, wetter followed by drier conditions & increased isolation for freshwater fish
• Death Valley – transitioned from lake to desert
• Fish species – Pleistocene relicts
Non-equilibrium populations created by once widespread biotas
being diminished in size oversaturated communities then lose
species richness to find new equilibrium
![Page 79: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/79.jpg)
Undersaturation?
• North America - Great Lakes
• Gouged out by glaciers, then filled with water during retreat
• Dispersal barriers for some fish species left these lakes with impoverished species richness
![Page 80: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/80.jpg)
Can ETIB be applied to terrestrial areas?
• Terrestrial islands (e.g. mountain tops, habitat fragments etc.)
• Same concerns as real islands (rescue effects, target area effects)
• Ocean vs terrestrial matrix?
• Other habitat characteristics important
![Page 81: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/81.jpg)
![Page 82: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/82.jpg)
Koocanusa reservoir is 90
miles long
![Page 83: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/83.jpg)
![Page 84: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/84.jpg)
Are protected areas “islands of habitat” in a matrix (ocean) of unsuitable habitat?
![Page 85: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/85.jpg)
Can ETIB be applied to nature reserve design in terrestrial areas?
SLOSS debate (1970s-80s)
Single large reserves or
several small reserves
Diamond vs Simberloff
Diamond – SL
Simberloff – both valuable
![Page 86: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/86.jpg)
In homogeneous environments, what would island biogeography predict about SLOSS debate?
– Larger reserves with better connection to other protected areas preserve greater biodiversity
• In heterogeneous environment?
– Depends, but several small reserves may be valuable to protect local areas of high biodiversity
![Page 87: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/87.jpg)
Edge Effects
• Habitat edges generally have negative effects on forest species
• Edge is a constant effect (for a specific species/environment)
![Page 88: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/88.jpg)
Habitat Fragmentation
• The splitting or breaking apart of habitat
• Area may be preserved, but habitat function reduced
• Effects are species specific
![Page 89: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/89.jpg)
Edges as ecological barriers
Negative impacts result from:
• Altered abiotic conditions
• Reduced connectivity
• Increased exposure
• Modified habitat
• Habitat loss
![Page 90: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/90.jpg)
Application of island biogeography to reserve design
![Page 91: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/91.jpg)
Can ETIB be applied to nature reserve design in terrestrial areas?
Corridors?
e.g. Banff NP
![Page 92: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/92.jpg)
Several small reserves to protect high diversity habitats & riparian corridors
Pine
grasslands
Bald cypress
swamps
Carnivorous
plants
![Page 93: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/93.jpg)
Yellowstone to Yukon Initiative
• Large core protected reserves
• Connected corridors
![Page 94: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/94.jpg)
Do terrestrial islands exist? A case study
Grizzly Bear (ursus arctos horribilis)
• Listed as threatened under the Endangered Species Act in 1975
• Historically, > 50,000 bears westwide
• Currently, 1200-1400 bears total in the U.S.
• 32 of 37 populations of grizzlies extirpated by 1975
• Only 5 populations currently exist in the U.S.
![Page 95: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/95.jpg)
1. North Cascades (9,500 mi2)
– < 20 bears
2. Cabinet-Yaak-Selkirks (2,200 mi2)
– 40-50 bears
3. Northern Continental Divide (9,600 mi2)
– 750 bears
4. Selway-Bitterroot (5,600 mi2)
– 0 bears
5. Greater Yellowstone (9,200 mi2)
– 550-650 bears
![Page 96: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/96.jpg)
• North Cascades, Cabinet-Yaak-Selkirks, and Northern Continental Divide all connected to Canadian populations
• Habitat and land use differences important – NC & CYS suffer from small population size, fragmentation, heavy roading,
and high motorized vehicle use
– NCDE largely wilderness and National Park
![Page 97: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/97.jpg)
• Yellowstone and Selway-Bitterroot are “islands”
• Since extinction of grizzlies in S-B, only one individual known to successfully migrate from NCDE or CYK
– Discovered when shot by black bear hunter
• No grizzly has ever traveled from the Greater Yellowstone ecosystem to another core area
![Page 98: Welcome to Biogeography](https://reader033.fdocuments.in/reader033/viewer/2022052419/586d6b541a28ab111a8ba36d/html5/thumbnails/98.jpg)
Franklin & Lindenmayer 2009
• Main points:
– Characteristics of the matrix matter to species
– Species habitat needs occur at different scales
• e.g. grizzly bear vs. salamander
– Not all species will respond the same
– Matrix in terrestrial systems is often not analogous to ocean matrix for islands
– Application of island biogeography is not simple
– Reserves are necessary, but not enough
• How the matrix is managed may be critical to species survival and ability of matrix to function as a filter/corridor