Conservation Biology

Wednesday, May 24, 2006


1. Introduction and History
What is conservation biology?
Relatively new, multidisciplinary science that has developed in response to concern over loss of biodiversity
Definition of the World Conservation Strategy of 1980: “The management of human use of the biosphere so that it may yield the greatest sustainable benefit to the present generation while maintaining its potential to meet the needs and aspirations of future generations.”
Three aims of the Strategy: 1) maintain essential ecological processes and life support systems, 2) preserve genetic diversity, 3) ensure the sustainable utilization of species and ecosystems
Why conserve?
Utilitarian (sustainability of consumables, eco-tourism, nutrient & water cycling, use in pharmaceuticals, knowledge and education, aesthetic beauty)
Non-utilitarian (ethics, the right of a species to exist)
How many species are there?
Approximately 1.5 million species are described
New species constantly being discovered
History/origins of conservation biology:
Roots can be traced to ancient religious and philosophical beliefs regarding the relationship between humans and nature
Protected areas have existed in India since the 4th century B.C.
The first National Parks were established in Europe in the 16th century
In North America, the Creation of Yellowstone National Park in 1872

2. Threats to biological diversity 1: Habitat loss and fragmentation
Habitat destruction is the primary threat to biodiversity
Caused by agriculture/development – Human overpopulation
Leads to:
Reduction of total habitat area
Increase in edge (edge effects)
Decrease in interior habitat
Isolation of fragments from each other
Tropical rain forests are particularly at risk – occupy 7% of the Earth’s land surface, but account for 50% of its species

3. Threats to biological diversity 2: Overexploitation
Maximum sustainable yield – the greatest amount of a resource that can be harvested each year and replaced by population growth without detriment to the population
Animals or plants killed or harvested for food, sport, resources (e.g. ivory, timber), protection, medicinal uses
Many species have become endangered or gone extinct due to human overexploitation – Dodo is a classic example
Overexploitation caused by increasing rural poverty, more efficient methods of harvesting, globalization of the economy, growing human population

4. Threats to biological diversity 3: Exotic species
Intentional (e.g. for food or beauty) or accidental (e.g. zebra mussels in ballast waters) introduction of plants or animals to non-native areas
Estimated to account for 40% of the extinctions over the past 400 years
Exotic diseases can also be a problem (e.g. Rhinderpest – brought to Africa from Asia)
Ways to deal with this problem – physical removal, barriers to prevent spread, biocontrol
S.A. example – Argentine ants, which do not bury seeds, are changing the ecology of the Cape fynbos

5. Threats to biological diversity 4: Environmental factors
Aquatic – Litter, oil spills, fertilizers and pesticides, chemicals
Terrestrial – light, waste disposal
Global warming
Acid rain

6. When is a species endangered and where should conservation efforts be placed?
Red Data Books – classify species as endangered, vulnerable, or threatened
Mace and Lande’s criteria for threatened species
How do you decide which species should receive priority in terms of funding and research? Select species with large habitat requirements and you automatically protect smaller species as well. Should we make the greatest effort to conserve species that are taxonomically rare or unique (e.g. giant panda, tautara)? Alternatively, is the goal of conservation to allow evolution to take its natural course and therefore concentrate efforts on newly evolving species (e.g. cichlids) rather than relict species?

7. Extinction
Minimum viable population size – smallest isolated population having a 99% chance of remaining in existence for 1000 years. Concept defined in 1982 by Mark Shaffer studying grizzly bears in Yellowstone.
Extinction rates are currently measured at about 100-1000 times the natural background rate
What makes a species vulnerable to extinction? Narrow geographic range, only one or a few populations, small population size, declining population size, low population density, species with large home ranges, animals with a large body size, ineffective dispersal, seasonal migrants, low genetic diversity , specialized niche requirements, species that form permanent or temporary aggregations, species that are hunted or harvested by people
Effective population size (number of breeding individuals) vs. actual population size
50/500 rule

8. Conservation genetics
Apply genetic methods to deal with conservation issues
Two purposes: 1.) maintenance of genetic variability in populations, 2.) identification of evolutionary significant units for preservation
Example: Red Wolf – found to be a hybrid between the gray wolf and coyote. Is this a wasted conservation effort?
Population bottlenecks
Example: Cheetah – very low genetic diversity

9. Reserve Design and Selecting Areas to Protect
SLOSS debate
Size, shape, number of reserves
Wildlife corridors
Identifying land for nature reserves
Gap analysis
Island biogeography as a model for reserves
Biodiversity “hotspots” – identified by Myers (2000) as areas with both high endemicity and high level of threat. To qualify as a terrestrial hotspot, an area must have 0.5% of the world’s vascular plant species and have lost at least 70% of its original expanse. To qualify as a marine hotspot, an area must be a centre of endemism with an average threat level of 1.67 on a three-point scale.
World Heritage Sites
Example of Cape flora – best design would be multiple small reserves

10. Managing Protected Areas
Predator-prey cycles
Reintroducing locally extinct species
Regulating human activities inside protected areas
Local communities

11. Conservation Strategies for Species
In situ methods
Protection of individuals from specific threats
Ex situ methods
Seed banks
Botanic gardens, zoos and aquaria
Cross-fostering and artificial incubation
Vegetative propagation and tissue culture
Re-creation of extinct species from DNA