ge/bi307 mar 10, 2007 outline 1. island theory and the...
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GE/BI307 Mar 10, 2007Reserve Design: The SLOSS debate and Beyond
Outline
1. Island theory and the SLOSS question.2. Point and counterpoint 3. Beyond SLOSS: what have we learned about
reserve design?
1. Island theory and the SLOSS question.
Species-Area relationship predicts larger areas contain more species.
Taken at face value, this suggests that 1 large reserve should contain more species than several smaller reserves totaling the same area.
Touching off the debate: Diamond J. 1975. The island dilemma: lessons of modern biogeographic studies for the design of natural reserves. Biological Conservation 7:129-146.
‘bigger is better’
‘SL better than SS’
‘closer better’
‘circular better than linear’
‘connected better than isolated’
‘minimize edges’
Other key ‘pro-SL>SS paper:
Terborgh J. 1976. Island Biogeography and conservation: Strategy and Limitations. Science 193:1029-1030.
Daniel Simberloff –U. Tennessee (via Fl. State)
Lawrence Abele –Florida State University
Contrarians: Simberloff DS, Abele LG. 1976. Island Biogeography theory and conservation practice. Science 191:285-286.
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Simberloff argument:
When z<1 (always the case) half the area preserves more than half the species.
Thus, two reserves of ½ area may contain more than the species in the full area.
What key assumption does this depend on?
Response from Diamond:
Larger areas are more likely to contain the wide-ranging species that are often most threatened.
The sum of species in small areas may exceed a large area, but may be composed of generalists and weeds.
Why several small can be better than single large:
1. Habitat diversity.2. Focal species conservation, e.g Cape Floral Province
Cape Floral Province:-68% of species are endemic-53 species of endemic Proteacea species restricted to 1 or 2 populations-Each population occupies 5 km2 or less, contains less than 1000 individuals.-A few large parks would completely miss many of these species.-Many smaller, scattered parks would be more effective in this case.
Whatever the merits of Diamond’s geometric reserve design recommendations, all would agree that these simple rules have been adopted uncritcally (e.g. 1980 World Conservation Strategy,World Conservation Union)
“I suspect workers are growing more weary of it thanapproaching any agreement on its resolution”
– Craig ShaferNature Reserves: Island Theory and Conservation Practice 1990
I wholeheartedly agree…
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Beyond SLOSS
Consensus:
Strategies for conservation depend on the group of species underconsideration and specific circumstances. (shift to autecological focus from synecological focus).
Corralary: There has been a shift away from Equilibrium Theory and toward Minimum Viable Population/ Minimum critical size analysis.
Large reserves are desirable, but well-managed small reserves have an important role in protecting focal species of value.
Types of focal species:
1. Keystone species: many others depend on it (e.g. Beaver)2. Umbrella species: large range protects many other species (bear)3. Flagship species: public appeal (e.g. great blue heron)4. Indicator species (frogs)5. Vulnerable species: Endangered Species List.
Recognizing the importance of buffers and corridors for focal species:
Effective corridors must be designed with care – e.g., many animals move along riparian zones but not other pathways.
Marine reserves:
•Most island biogeography theory has been applied to conservationof terrestrial habitats, not marine.
•Aquatic reserves largely under-studied. -Dispersal mechanisms, characteristics largely unknown.- Pollution may have more subtle/widespread effects in
aquatic systems than in terrestrial
Conservation strategies-Primack
-The role of humans
Humans and Nature Apart:
“Protected areas are a seductively simple way to save nature fromhumanity. But sanctuaries admit a failure to save wildlife and natural habitat where they overlap with human interests, and that means 95% or more of the earth’s surface. Conservation by segregation is the Noah’s Ark solution, a belief that wildlife should be consiged to tiny land parcels for its own good and because it has no place in our world. The flaw in this view is obvious: those land parcels are not big enough to to avert catastrophic species extinciton by insulratization or safe enough to protect resources from the poor and the greedy. Simply put, if we can’t save nature outside protected areas, not much will survive inside; if we can, protected areas will cease to be arks”.
D. Western et al. 1989.
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Case study: Marine Reserve Design
Key challenges to marine reserve design:
-Almost no application of an increasing body of theory of large marine reserves.
-Some theory suggests need to protect >20% of habitat for fisheries, but no agreement on how much habitat needed to protect biodiversity.
-No consensus on how to maintain ecological links (connectivity) between reserve elements.
Focus area: Gulf of California.
1st step: Gather data on habitats and species.
A priori goals:
1. Protect 20% of each representative habitat2. Protect 100% of rare habitats & areas with highest species
richness.3. Protect ecosystem function by protecting larval sources and
larval connectivity through dispersal (keep food chain from collapsing)
Thus, this is habitat and community focused more than focused onsingle species.
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Methodological Approach:
A. Gather Spatial Information on:
1. Fish diversity as a function of geography (latitude, depth predict 66% of fish diversity)
2. Area of each habitat3. Larval sources (diving and interview fisherman)
B. Create maximum reserve map preserving all diversity, then whittle it down based on:
- smallest number of reserves that meet % protection goals and ensure larval connectivity.
Many possible combinations of reserve number, size, and separation distance. How to optimize?
1. Make an educated guess about larval dispersal: 100 km max.
2. Use sophisticated geometric optimization model:
“Spatially explicit simulated annealing algorithm (SITES/SPEXAN)Interfaced with a GIS system (ESRI Arc View).”
“This algorithm designs and analyzes portfolios of sites from a universe of territorial units… attempts to meet predefined, quantitative conservation goals using as few sites as possible”
- constrained by 100 km distances between any 2 units.
Biologically optimal network Biologically and socio-economically optimal network.
-includes overlay of fishing intensity maps.
.
Key result: This approach did not significantly decrease the number of desired conservation goals
Key benefits of this approach:
-objective method (more politically defendable)
-Stepwise procedure (biologically optimal -> socially acceptable) presents policy makers with ability to weigh costs and benefits, set priorities.
Key limitation: based on shaky information of dispersal distances. Likely to affect marine reserve designs for a long time.
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Important to keep in mind:
Case study from New Guinea: (Diamond 1986)
1. Political Geography/zoning, as in most other cases, looms large,but particularly interesting in New Guinea:
- Irian Jaya under strong centralized govt. (Indonesia). Top-down control over land use/zoning. Relatively easier to implement national nature reserve system.
- Papua New Guinea – much more political power rests in local communities, tradition of freedom from higher authority. Naturereserves will depend much more heavily on local decisions.
Diamond focuses on Irian Jaya.
Sorex vagrans, vagrant shrew
shrews
Sorex palustris, water shrew
Mustela erminea, short-tailed weasel
Marmota flaviventer, yellow-belliedmarmot
Golden-mantled Ground SquirrelSpermophilus lateralis Belding’s Ground Squirrel
(Spermophilus beldingi)
Unita chipmunk Eutamias umbrinus
Northern Pocket Gopher,Thomomys talpoides
Long-tailed Vole, Microtus longicaudus
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Neotoma cinerea, Bunker's Woodrat
Zapus princeps, western jumping mouse
American Pika, Ochotona princepsLepus townsendi, snowshoe hare
Case study: Marine Reserve Design Key challenges to marine reserve design:
-Almost no application of an increasing body of theory of large marine reserves.
-Some theory suggests need to protect >20% of habitat for fisheries, but no agreement on how much habitat needed to protect biodiversity.
-No consensus on how to maintain ecological links (connectivity) between reserve elements.
Focus area: Gulf of California.
1st step: Gather data on habitats and species.
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Rodoliths – ‘unanchored’ coral algaeBlack coral
Goliath grouper – commercially important, large rangingBroomtail grouper – commercially important, large ranging
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A priori goals:
1. Protect 20% of each representative habitat2. Protect 100% of rare habitats & areas with highest species
richness.3. Protect ecosystem function by protecting larval sources and
larval connectivity through dispersal (keep food chain from collapsing). Focus on large commercial fish.
Thus, this is habitat and community focused more than focused onsingle species.
Methodological Approach:
A. Gather Spatial Information on:
1. Fish diversity as a function of geography (latitude, depth predict 66% of fish diversity)
2. Area of each habitat3. Larval sources (diving and interview fisherman)
B. Create maximum reserve map preserving all diversity, then whittle it down based on:
- smallest number of reserves that meet % protection goals and ensure larval connectivity.
Many possible combinations of reserve number, size, and separation distance. How to optimize?
1. Make an educated guess about larval dispersal: 100 km max.
2. Use sophisticated geometric optimization model:
“Spatially explicit simulated annealing algorithm (SITES/SPEXAN)Interfaced with a GIS system (ESRI Arc View).”
“This algorithm designs and analyzes portfolios of sites from a universe of territorial units… attempts to meet predefined, quantitative conservation goals using as few sites as possible”
- constrained by 100 km distances between any 2 units.
Biologically optimal network
Biologically and socio-economically optimal network.
-includes overlay of fishing intensity maps.
.
Key result: This approach did not significantly decrease the number of desired conservation goals
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Key benefits of this approach:
-objective method (more politically defendable)
-Stepwise procedure (biologically optimal -> socially acceptable) presents policy makers with ability to weigh costs and benefits, set priorities.
Key limitation: based on shaky information of dispersal distances. Likely to affect marine reserve designs for a long time.
Important to keep in mind:
Case study from New Guinea: (Diamond 1986)
1. Political Geography/zoning, as in most other cases, looms large,but particularly interesting in New Guinea:
- Irian Jaya under strong centralized govt. (Indonesia). Top-down control over land use/zoning. Relatively easier to implement national nature reserve system.
- Papua New Guinea – much more political power rests in local communities, tradition of freedom from higher authority. Naturereserves will depend much more heavily on local decisions.
Diamond focuses on Irian Jaya.
GE/BI 307 April 10, 2007
Minimum Viable Populations and Population Viability Analysis
1. What is MVP?2. What factors determine MVP?3. What is PVA?4. How are PVA’s conducted? Case study.
1. What is MVP?
Shafer 1981: “A MVP for any given species in any given habitat is the smallest isolated population having a 99% chance of remaining extant for 1000 yrs despite the foreseeable effects of demographic, environmental, and genetic stochasticity, and natural catastrophes”
- Not a fixed quantitative definition; other percentages and time periods may be used.
- Analagous to flood control measures. Plan for extreme events rather than mean conditions.
1. What is MVP?
Related to Minimum Dynamic Area:
Once MVP is estimated, characteristic population densities (# individuals per area) can be used to determine minimum area requirements.
Similar to the Insular Distribution Function described earlier (but that function includes isolation)
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1. What is MVP?
Thus, MVP ‘inverts’ a core question addressed by the equilibrium theory:
Instead of: “How many species exist in X area?”
MVP asks: “How much area is needed for Species X?”
1. What is MVP?
Estimates range from 500-10,000, but single numbers can be (and have been) very misleading.
But there have been interesting and suggestive observations…
Bighorn sheep, SW US
50 individuals appears to be a threshold for century scale survival.
No single cause apparent – likely several factors.
What are possible factors?
(figures from Primack)
2. What factors determine MVP?
Deterministic factors: logging, hunting, pollution, etc. Things we can control.
Stochastic factors:
- Genetic problems associated with low population sizes (genetic drift, impoverishment, inbreeding depression)
- Demographic fluctuations (variation in birth, death rates and offspring gender distribution)
- Environmental stochasticity (catastrophes, floods, drought, fires, etc.)
Often these factors add to the genetic extinction vortex.
More on demographic effects:
Recall effective population size:
Ne = 4x Nm x Nf/(Nm + Nf)
This is for breeding animals, not all animals!
Age, health, behavior (e.g. monogamy vs. polygamy) may all affect breeding patterns.
Effective populations can therefore be much smaller than actual populations.
E.g. 1000 alligators may only have 10 animals, 5 male, 5 female that are of the right age and health to breed. Effective population is 10, not 1000.
More on demographic effects:
Not just the number of breeding animals matters, but the sex ratio as well.
Ne = 4x Nm x Nf/(Nm + Nf)
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Consider elephant seals: plausible case – 6 breeding males, 150 breeding females. Assume 6 males mate with 25 females each.
Plugging into the above, this leads to an effective population of 23, not 156.Thus, polygamy is discounted in Ne, and reflects the limited genetic variation due to unequal sex ratio.
More on demographic effects:
Effective population can be computed over generations:
Ne = t/(1/N1 + 1/N2 + 1/N3 +…)
Where t= number of generationsNx = Ne at year x.
Example: 5 generations of endangered butterfly, with 10, 20, 100, 20, and 10 breeding individuals.
Ne = 5/(1/10 + 1/20 + 1/100 + 1/20 + 1/10) = 5/(31/100) = 16.1
Note: if there were 500 individuals in year 3, we would get only 16.6. Thus, effective population sizes integrated over time are impacted much more by the “lean” years – “population bottleneck”
Example of “genetic bottleneck” – Lions in Ngorongoro Crater, Tanzania
Stomoxys calcitransBiting fly 1961-62
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Ominous telltales, sperm from crater males (middle and right) show abnormalities when compared with a normal sample. Reproductive physiologist David Wildt and his colleagues at Washington's National Zoo found structural deformities in more than half the sperm of each male tested, strong evidence of inbreeding. The continuous decline of genetic diversity since 1969 is perhaps linked to a falling reproductive rate.
photo credits: David Wildt and Jo Gayle Howard,source: National Geographic, July 1992, p.133
The 50/500 “rule” (Soule and Gilpin):
A variety of breeding studies suggested that inbreeding depression becomes a major factor driving extinction in sexually reproducing populations less than 50 (effective pop. Size).
And that the genetic impoverishment (loss of alleles) occurs below effective population sizes of 500.
This rule has been taken very literally and was sometimes used to justify not protecting very small populations because they were considered doomed. (Simberloff complaint).
Never intended to be taken so literally.
Recall genetic extinctionVortex from before.Add:Demographic stochasticity
Environmental Stochasticity
Thus, Situation can getEven worse.
Including genetic,Demographic, andEnvironmental factorsAll together is doneIn Population ViabilityAnalyses
3. What is Population Viability Analysis?
- A much more integrative framework for determining MVP.
- Goal: determine in an integrative manner how deterministic and genetic, demographic, and environmental factors together determine the probability of extinction for a population, and thereby guide practical, specific conservation strategy.
- Spurred by very practical problems (Gilpin and Soule) – how to save specific species in specific situations.- how to justify conservation of species at even very low numbers (beyond the 50/500 rule).
- No standardized methodology at present, case by case.
Case study: Rhinos – all extremely endangered
African black rhino
Indian rhinoJavan Rhino
African Northern white rhino
Sumatran rhino
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Context: Rhinos used to exist not only in Africa and Asia, but Europe and N. America.
Extinct from N. America ~ 5 Mya
Paraceratherium, Eurasian grasslands, 10,000 yrs ago
teleoceras, North America4-17 mya
Coelodonta antiquitatis, Wooly Rhino, Eurasia
Extant Rhinos: Two overriding threats: Habitat destruction and poaching.
Rhinos present a very compelling case study because:
- they are all very endangered- Each species has unique problems, allowing comparison
and contrast to Population Viability Analysis and conservation strategies – one solution does not fit all.
How is this the case? First lets review some of the key features of each species…
Facts: African White Rhinos (ceratotherium simum)
-Northern and southern sub-species-Northern sub-species muchRarer (50 individuals)-about 11,100 remaining-Largest species of Rhino-Least endangered of Rhinos-Grazer, lives in long and shortGrass savannahs.
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Facts: African Black Rhinos(Diceros bicornis)Bicornis = “two horns”
-About 3610 currently remaining.-In 1970, about 65,000-Low point: 2300 in 1992-3-Fragmented into isolated populations of ~75-Anti-poaching laws enacted.-Browser, eats leaves and branches of shrubsAnd trees.
Facts: Indian Rhino (Rhinoceros unicornis)
-Best success story: from under 200 (early 20th century) to 2400 today.-Poaching remains a threat.-Mostly aquatic grazer – most amphibious of all rhinos.
Facts: Javan Rhino (Rhinoceros sondaicus)
-Rarest of all species: less than 60 animals in only 2 locations –vietnam and indonesia.-weak protection against poaching.-Smaller than indian rhino-Adaptable eater – both browser and grazer – mostly along watercourses.
Sumatran rhino
Facts: Sumatran Rhino (Dicerorhinus sumatrensis)
-Most endangered of all species: fewer than 300 individuals in very small and fragmented populaitons.-Numbers declined by 50% in last 15 years.-No sign of stabilizing population numbers.-Habitat: dense tropical forest, mostly browser from a great variety of plant species.
Past and present distributions.
Habitat loss and poaching.
Fragmented populations –big risk of genetic impoverishment.
While inbreeding depression is the most immediate concern, the situation differs among the species in interesting ways. This impacts PVA and conservation strategies.
For example, Indian Rhino shows high levels of genetic diversity(heterozygosity) even though its population numbers are low.
.
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Nepalese sub-species of Indian Rhino declined to 100 individuals, with 30 breeding.
Population has recovered to 400.
How could this species have retained genetic diversity even though it clearly went through a population bottleneck?
Answer not entirely clear. Speculation: high mobility of this species (moves relatively long distances) may have provided enough gene flow to maintain heterozygosity.
Lesson: low population sizes do not always lead to genetic impoverishment. Species-specific traits need to be considered.
.
Contrasting situation:
African Black Rhino: six living subspecies, very low genetic variability within subspecies – much more concern about inbreeding depression than Indian rhino for same population size.
Can we thus assume that the Indian Rhino is in better shape to avoid extinction compared to the African black Rhino?
Not so easy…
.
Another major contrast:
Indian rhino under much more pressure from habitat loss. Humansnow settle almost all of the land occupied by Indian Rhinos, andthey have no opportunity to expand back (unless humans go away)
African Black Rhino not losing habitat nearly as much. Much of its range is still open.
.
Differing conservation strategies:
Emphasize genetic enrichment in Black Rhino- move individuals between populations (gene flow)- Bring all or most black rhinos together in a single breeding
population.- risk losing micro-environmental adaptations though
Indian Rhino: prioritize habitat protection more than genetic diversity.
Sumatran Rhino: 4 scattered populations, genetic evidence suggests 1 (Borneo) is far different from the other 3. If possible, manage Borneon population separately for breeding/conservation.
Sumatran Rhino relocation - 2005GE/BI307 April, 2007
Population Viability Analysis Exercise
(Example from Primack – Essentials of Conservation Biology)
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The Scenario:
Endangered toad, formerly widespread, now occupies a small, isolated mountaintop.
At present, 10 toads.
Mountaintop can accommodate a maximum of 20 toads.
Toads complete life cycle in 1 year.
Form monogamous mating pairs.
Each pair can produce 0 to 5 offspring (all equally likely, determine by coin flip)
Sex of offspring is random (coin flip)
Possible Extensions:
1. Alter carrying capacity (from max of 20 to 15, or 30)2. Introduce environmental disturbance by imposing
50% mortality in year X due to a drought.3. Alter range of offspring allowed due to increases or
decreases in food.4. Polygamy, longer breeding life span.5. More demographics: infant, juvenile, adult, elderly
age distributions, mortality rates.6. Introduce inbreeding depression into reproductive
fitness.
GE/BI307 Apr 19, 2007
Population Viability Analysis:
A current example with critically endangered Orangutans
Outline
1. Background on Orangutans2. Setting up the PVA model3. Demonstration simulation.
4. Summary of key results5. Conclusions and Conservation
Implications
“it is probably the vast extent of the unbroken and equally lofty forest which is the the principal attraction to the Orangutan. These forests are its open country, the place best adapted to its mode of life, where it can roam in every direction with as much facility as the Indian in the prarie or the Arab in the desert. The dry grounds are more requented by man, more cut up by clearings and by low second-growth jungle, in which progression is more difficult, where it is exposed to danger, and where probably its favorite food is less abundant”
- Alfred Russel WallaceOn the habits of the Orangutan of Borneo 1856.
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Current Distribution
Sumatran(Pongo abelii)IUCN: critically endangered 2003
Bornean(Pongo pygmaeus)IUCN: endangered 2003
General features:
•Most arboreal of all great apes – makes new tree nests every night - can’t live out of forests
•Loves swamp forest, can also live in dryland forest.
•Eats fruit, insects, leaves, meat
•Usually considered solitary, but wide variety of cultures. Some very gregarious
•Major threats: habitat destruction, pet trade.
Demographic features:
•Females: reach puberty age 10, reproductive from 15-50. Gestation period ~ 250 days.
•1 born at a time; birth interval 7-9 yrs. Females can produce at most 4 surviving offspring. Infant mortality to age 1: 9%
•Females stay put; males wander.
•Young weaned/carried until about 4 yrs; independent at 6-7 yrs.
•Males: sexually maturity around 12 yrs old, full maturity with secondary sexual characteristics takes another 10-20 yrs.
•Lifespan: Avg. 45 yrs in wild, up to 59 in captivity
Differences:
-Large genetic distance (as much as is considered in different species in other primates like chimps)
-But produce healthy, viable hybrids in captivity.
-Sumatran compared to Bornean:Fur: lighter, denser, longer.Faces: lighter, narrowerOverall, more gracile, and shorter thumbs, larger toes.
Large genetic and cultural difference informs conservation strategies –manage populations separately
Large genetic differences imply longer separation than simply last ice age.
Large river basins may have been barriers even during last ice age.
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Estimated total population (both species): 20,00050% reduction in population in last ten years.Major threats: illegal logging, pet tradeAccelerated due to civil Unrest (Suharto Regime Collapse 1998)
Culture reflected by differential tool use
What conservationists are up against: an almost impossible political backdrop.
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Orangutan Population Viability Analysis
Commission by IUCN Conservation Breeding Specialist Group
Final Report August 2004.
Goals:
Overarching: “ensure that orangutan populations are viable and secure for the next 1000 years. We will accept 0% risk of extinction over 1000 years”
1. Determine if wild populations still viable.
2. Determine how many separate populations are viable.
3. Identify priority areas for conservation action.
Goals 1 and 2 addressed using VORTEX
Vortex model development for Sumatran Orangutans
• Vortex was used to integrate all 4 kinds of extinction threats:
1. Deterministic = habitat destruction due to logging2. Stochastic = Genetic, Demographic, Environmental.
Vortex model development for Sumatran Orangutans
• Used 30+ year observational data set on demographics, habitat needs.
•Baseline model performed first – in the absence of any future habitat destruction.
•Human impact scenarios added in subsequent simulations (by altering carrying capacity).
Some Demographic inputs
Vortex model development for Sumatran Orangutans
•500 simulations run•1000 year runs (sounds long, but only 20 generations!)•Definition of extinction: 1 sex remaining.•Inbreeding depression: yes (4.06 lethal equivalents –obtained from genetic studies at zoos)
A lethal equivalent is the mean number of lethal allelles per organism. For example, 4 allelles each with 25% lethality = 1 lethal equivalent.
•Mating system: short term polygyny
Some key results:
Baseline model (no continued logging, no environmental disturbances): populations above 250 appear to escape genetic problems and demographic stochasticity)
Note 250 is a precarious number and would likely lead to extinction after 1000 yrs. Also note 50 yrs is a very short time (~ 2 generations), so 0 PE is not very meaningful in this time frame.
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Logging: Some Orangutan habitats in Sumatra exposed to up to 20% annual deforestation rates.
Even much lower rates compound to large habitat loss over just a few generations. Logging must pretty much cease in existing Orangutan habitats.
Busy table; bottom line:
All populations extinct at 1000 yrs unless NO logging.
(assumes lost forest is not restored).
A dire situation when one considers current logging rates.
Let’s take a look at results from a couple of the extremes (in red boxes).
Sealuwah is likely too far gone for even reforestation to help long term survival. Additional intervention is likely to be necesssary.
Other extreme: W. Leuser – only cessation of logging allows long term viability and even then, only to 1000 yrs.
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Summing up: all Sumatran Orangutans Key Conservation Considerations:
-Pretty simple message: logging must cease to avoid extinction. Ceasing logging after 5 years may allow larger populations to persist long term. No evidence that any action is being taken.
-Essentially, same message for Borneo
-250 individuals sustainable in short term, 500 in long term.
-Of 13 isolated habitats, only 7 have more than 250.
-Of these 7, 6 are subject to 10-15% logging
-Smaller populations linked by occasional exchanges could contribute to overall metapopulation stability.
Conservation Recommendations based on Vortex:
1. Stop illegal logging2. Stop road building3. Connect East and West Leuser4. Forest rehabilitation
Other recommendations:-continue funding for existing conservation projects-World Heritage status for Leuser Ecosystem-Education outreach programs-Ecotourism (post-war option)-Helicopter patrols for rapid enforcement-Develop/encourage local NGO’s-Incentives for people to move out of Leuser Ecosystem-Work closely with local governments, tribal leaders-International and national media campaign.-Sustainable income activities for local people
General Take Home Messages:
-PVA offers us an objective, quantitative tool to assess the viability of endangered species, based on concepts of biogeography and conservation biology.-threats mount.
-In combination with tools including GIS and Remote Sensing, there are excellent opportunities for professional or academic careers in Biogeography
-these careers are sorely needed as global extinction threats mount.
The Puzzle of the Pronghorn and Pleistocene Rewilding
Applied Conservation BiogeographyGE/BI307 April 25, 2007
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“In 1915, after the American pronghorn was almost hunted to extinction, there were only 15,000 animals. Today, there are less than 700,000, but some pronghorn are still on the brink of extinction.” - National Wildlife Federation
Kingdom: AnimaliaPhylum: ChordataSubphylum: VertebrateClass: MammaliaOrder: Artiodactyla (even-toed ungulates (hoofed mammals))Family: AntilocapridaeGenus: Antilocapra (sub) Species: American, Sonoran, Oregonian, Mexican, Penninsular (baja)(only 300-500 sonoran left!)
Family Antilocapridae (pronghorn antelope)
Family Bovidae (antelopes, cattle, gazelles, goats, sheep, and relatives)
Family Camelidae (camels, llamas, and relatives)
Family Cervidae (deer)
Family Giraffidae (giraffes and okapis)
Family Hippopotamidae (hippopotamuses)
Family Moschidae (musk deer)
Family Suidae (hogs and pigs)
Family Tayassuidae (peccaries)
Family Tragulidae (chevrotains and mouse deer)
An aside…
Conservation of pronghorns has been benefited tremendously by “Gap Analysis”
Procedure: map known range of a species, correlate to climate, soils, topography, vegetation
Use geospatial info (GIS, remote sensing) to locate suitable areas for which animals may exist but have not been documented, where they may have once been located, and where they may be
successfully introduced or re-introduced.
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Continuing threats include:
Habitat fragmentationIllegal huntingGrassland conversion to cropsHabitat degradatation by grazing livestockRanchers’ intolerance
Eyesight/hearing extremely acute.
The pronghorn is the second fastest land animal in the world, almost as fast as the cheetah. It is the fastest in the Western Hemisphere.
60 MPH – faster than wolves, coyotes, thompson’s gazelle. No N. American predator that can match adult’s speed/endurance.
Why is this animal in N. America?
American cheetah – Acinonyx trumaniExtinct by 13,000 years ago Should we bring back the Cheetah?
Arguments for re-wilding
-restore ecological/evolutionary interaction with pronghorns
-African species very closely related to extinct American species
-African species highly endangered
-Ecotourism benefits/alternative economy in depressed great plains.
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More general proposal for re-wilding N. America
Rationale: almost all conservationists in N. America have sought to return species/habitats to pre-columbian times (1492)
The reality is that N. America has been highly disrupted by loss of megafauna from 13000 years ago – a snapshot in evolutionary time.
Large scale changes in N. American landscapes (e.g. loss of grasslands due to woody encroachment) may be a vestige of pleistocene overkill. Thus, restoring megafauna may actually be a more desirable conservation goal.
Symbols represent horses (Equus caballus and E. asinus in black; E. przewalskii and E. hemionus in grey), Bolson tortoises, camelids, cheetahs, Asian (grey) and African (black) elephants, and lions. a, The likely timescale and area required to restore proxies for extinct large vertebrates. b, Conservation value and ecological role (interactivity with other species) on the landscape. c, Potential economic/cultural value versus potential conflict.
More general proposal for re-wilding N. America
Bolson tortoise, Gopherus flavomarginatus.Largest extant N. American reptile – 50 kg
Extinct Camel, Camelops hesternus
Bactrian Camel, Camelus bactrianus, extremely endangered, restricted to Gobi desert
Camels browse woody shrubs unpalatable to livestock grazers –may help to reduce woody encroachment into Great basin grasslands
AMERICAN LION panthera leo atroxAFRICAN LION panthera leo leo
Other endangered species in N. America may benefit from re-introduction of mega-mammals:
e.g. California Condor, a pleistocene relict
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More controversial: Introduce niche replacers, even if they weren’t a part of the “near-time”complement of large mammals.
e.g. Members of the Rhino family lived in N. America until about 7 million years ago.
Perhaps grazing/browsing rhinos were replaced by ground sloths.
No close replacement for ground sloths – could Rhinos fill the niche?
Re-wilding: Lots of recent press
Ecological Arguments against re-wilding:
-introduced species are not genetically the same-Disease transmission-Unexpected ecological consequences
Proponents acknowledge risks, propose initial introduction in highly controlled habitats.
Perhaps unlikely to have same risk of uncontrollable growth as introduction of smaller animals (e.g. cane toads in australia)
northern quoll Dasyurus hallucatus
control beetles that were destroying sugarcane crops
To learn more:
www.rewilding.org
Google Josh Donlan
Twilight of the Mammoths: Ice age Extinctions and the Rewilding of America
– Paul S. Martin,University of California Press, 2005
Re-wilding: Expanding and realizing the Concept
1. Rewilding outside of N. America: case studies
2. Mega-linkages: barrier removal for wildlife
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Case study #1:
Re-wilding Siberian Steppe
ScienceMay 16, 2005
-Not just a reserve park, but a test of function of megafauna in ecosystem processes and global change.
-Did megafauna maintain high productivity grasslands (and the 500 GT Carbon in boreal soils) that have vanished, replaced by low productivity heath/moss?
-Can they return moss/heath to carbon sequestering grassland?
Less than 5000, restricted to northern China
Musk Oxen – introduced during Cold War to US FWS
Wood BisonBison bison athabascae
Yakutian horses: help reduce the effects of global warming by stabilizing vast expanses of grassland?
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Pleistocene Park. This territory in the Republic of Yakutia is roughly an even split of meadow, larch forest, and willow shrubland. This Siberian region could become the venue for a reconstituted ecosystem thatvanished 10,000 years ago. CREDIT: S. ZIMOV
Case study #2:
Re-wilding Oceania’s depleted avifauna
Rationale:
Polynesian “Future Eaters” and Europeans devestated Oceania’s birdlife
But there are many tiny, forested, uninhabited islands/islets with few exotics (cats, rats, pigs).
Introduce endangered birds into these habitats – in some cases of which are within their pre-historical range.
LateNiuafo’ou
Niuafo’ou: inhabited, forest degraded, cats, rats
Late: uninhabited, forested
Megapodius pritchardiiPolynesian megapodeOnce widespread in Pacific; now in 1 tiny island in Tonga“critically endangered” –most severe rating –IUCN World Cons. Union
Re-wilding: Expanding and realizing the Concept
1. Rewilding outside of N. America: case studies
2. Mega-linkages: barrier removal for wildlife
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Critter Crossing: an example from Banff National Park
“Highway mitigation in Banff National Park, Alberta, is the only large-scale complex of wildlife mitigation passage structures in the world.” - Parks Canada
elk, deer, moose, wolves, cougars, black bears,
Banff grizzly bear
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•8-foot-high fencing on both sides of the highway•28 miles (45 km) of the highway• 22 underpasses - arched culverts, box culverts, and open-span bridges•two 164-foot-wide (50-meter-wide) overpasses.
Good for animals and good for people too!
The fence has cut ungulate (hooved animal) roadkill by 96 percent……and 35 months of monitoring animals' back-and-forth movement through the crossing structures has demonstrated that both ungulates and carnivores are using them.
Crossing designed to be near the animals' natural travel.Carnivores - structures close to stream corridors or drainage areas.
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Ungulates: structures far from carnivores and with a clear view of the structures' entrance
A work in progress: still learning more:
-black bears and cougars climb over the fence.
-eliminate dandelions (a delicacy for black bears) on the highway side of the fence, place additional wire mesh at a 90-degree angle on top of the fence.
-stricter limits on human activity near the Banff crossing structures -a strategy to increase the low numbers of large carnivores (especially wolves and female grizzlies) using the structures
Different responses by wildlife - How often they are used and how well they are accepted by wildlife varies between species and geographic area, and the reasons why are unclear.
Design specifications - There are recommended minimum dimensions for some ungulatespecies, but the needs of wide-ranging species are vague.
Influence of human activity - Our work in Banff has shown that human activity can influence how animals use passages.
Crossings for all species - Practically all of the research conducted to date has focused on single-species, such as elk or deer, and limited attention has been paid to multiple species or wildlife communities (e.g. large mammals).
Cost-effectiveness - Crossing structures are expensive, but a large research void exists in determining cost-effective designs
Parks Canada. .
The grandest scale of rewilding: megalinkages
Closer to home…One night every spring, most of Amherst's migrating salamanders use these tunnels to get to vernal pools where they mate and lay their eggs.
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