Bio 215 ch 55 Conservation Biology 1
I. Biodiversity is in crisis.
While extinction is a natural phenomenon, the current rate of extinction indicates that we are going to
have a problem in the future. This high rate of ecosystem degradation is being caused by Humans.
A. A number of examples indicate that the extinction rates are abnormally high
1) While we cannot be exactly sure how many species are becoming extinct, because we do not know what
all of the species are.
2) 11% of the over 9000 known bird species have a sharply decreased population
3) over 500 of the 20,000 known plant species also show this decreased population
4) About 20% of the known freshwater plant species have become extinct.
B. The major threats to biodiversity are habitat destruction, over-exploitation and competition by exotic
1) Humans cause most of the loss of habitat due to development, logging, war oilspills and other activities.
2) Humans also overexploit the wildlife with illegal trade ect of animal products.
3) Exotic species also cause a reduction in diversity.
C. Why is biodiversity vital to human welfare?
1) Some people like the diversity for its self worth and beauty. (biophilia)
2) Biodiversity is a vital resource that can provide new crops, fibers and medicines.
II. Location of Biodiversity
Biodiversity is not evenly distributed, it includes areas of gradual variation (clines), hot spots, concentrations and
ranges of migratory species.
A. A gradual variation in biodiversity correlates with geographical gradients.
1) Energy availability: the greatest light provides the greatest resources.
2) Habitat heterogeneity: tropical regions experience more local disturbances that contribute to greater
3) Niche specialization: predictability of tropical climate allows more organisms to specialize.
4) Population interaction: coevolution results in a tightly nit community that prevents any populations
from becoming dominant.
5) Clines are probably due to a complex combination of factors.
B. Biodiversity hot spots have high concentrations of endemic species (a small area with an exceptional
concentration of species. Endemic species = is not found anywhere else.
1) These areas are especially vulnerable because of their small size. Also many of these spots, Hawaii,
southern California, southern Appalachians, southeastern coastal states are currently experiencing
developmental pressures due to expanding populations.
C. Migratory species present special problems in conservation
1) For conservation, one would need to preserve at least two areas, the breeding grounds and the winter
grounds. This is not necessarily the best because you need to preserve areas in-between so that the
organisms can fly to and from. Also new studies also indicate that several areas may be used by the
birds under different stages of life.
III. Conservation at the Population and Species Level.
Endangered species: are species that are in danger of extinction in all or a significant portion of its
Threatened species: are species that are likely to become endangered in the near future throughout
all or a significant portion of its range.
A. The ultimate goal of conservation is sustainable genetic diversity.
1) Genetic variability within populations is as important as the number of species.
2) Currently conservation efforts lag far behind the rate of decline.
3) Scientists are concerned about saving Lineages, if not one species then one closely related to it.
4) Some of the techniques currently being used by biologists have not been tested.
B. Habitat fragmentation cause some divergent dynamics when populations are subdivided.
Human essentially form subdivided populations (metapopulation) that are small patches of habitat
surrounded by human activity. This tends to reduce the genetic variability of the population as a whole.
1) Source and sink dynamics in metapopulation
Source populations have a growing population
sink populations have a declining population
Bio 215 ch 55 Conservation Biology 2
The source populations tend to provide individuals to the declining population, reducing
C. PVA or population viability analysis: is s method of predicting weather a particular population will persist in
a specific environment.
1) It is a computer simulation that integrates info about sex ration, fecundity, reproduction, competition
and human effects.
2) Will usually predict long-term viability if periodic natural disasters are factored in.
3) A PVA is expensive and has to be continuously updated in order to function.
4) Minimum viable population size (MVP)
Most PVA are designed to predict the minimum viable population size. (smallest number of
individuals needed to propagate a population) aids in determining the minimum dynamic area
5) Estimating effective population size.
Is based on the number of adults that successfully breed.
the formula is NE=(4nNm X Nf) / (Nm + Nf)
Nm and Nf are the number of males and females respectively that are breeding.
Again a number of other effects can also effect N E like age of first breeding, genetic relatedness
among populations ect.
6) How genetic diversity effects survivability
Populations with low NE tend to inbreed reducing heterozygosity.
ins some species low genetic diversity may appear normal.
some populations tend to survive genetic bottlenecks (cheetah, northern elephant seals)
D. Analyzing and protecting some species may help sustain other species.
1) since producing a PVA requires extensive knowledge of a species and is a continuing process, not all
species can be modeled in this way.
2) the thought is that by preserving some species we may also be preserving others.
3) however, we must realize that MVP's differ for different species and while some organisms can survive
a lower population, others may not be able to do this.
4) often scientists will focus in on keystone populations whose populations have a disproportionally large
impact relative to the numbers of the population.
IV Conservation at the Community, Ecosystem, and Landscape Levels.
Landscape ecology is the application of ecological principles to the study of land use patterns.
Today's conservation efforts have both a large scale (many communities, whole biomes) and a local
(individual yards) scale.
some of the most important parts of a community are edges where there is great diversity, but if the
edges outweigh the entire community, this will lower species diversity.
movement corridors are needed to move individuals from one patch of area to another.
A) Nature preserves must be a functional part of the landscape.
1) it is predicted that less than 10% of the biosphere will be protected as nature reserves. If this is the case, we must
find ways to live in concert with the biomes that we live in, and find ways to minimally impact the organisms
2) Restoration ecology applied ecological principles to find ways to restore degraded ecosystems as close to their
original state as possible.
in bioremediation, we use living organisms to clean up polluted areas.
in augmenting ecosystems humans supply critical components that have been identified to restrict the rate of
recovery for a community. this way we can successfully speed succession and help the recovery of a
B) Sustainable development goals are reorienting ecological research and will require changing some human values.
1) the goal of sustainable development is to acquire the basic ecological information needed for intelligent
2) we need to know more about the global change and the interactions between climate and ecological processes.
3) we need to know ho biological diversity effects and has a role in maintaining ecological processes.
4) we need to know how the productivity of natural and artificial ecosystems can be sustained.