Applied Ecology

The principles of ecology are applied in many ways. There are obvious applications in conservation biology, but also in many other areas…

Examples:Saving endangered species using cloning

technology

Using knowledge of life history to evaluate risk of extinction for endangered species

Global climate change and the distribution of diseases

The maximum stainable yield problem

Plant (and animal) secondary chemicals as potential medicines

Evaluating the equilibria and potential for marine communities to recover from oil spills

Optimum design for national parks

Understanding the likely movement of toxic chemicals like pesticides and industrial pollutants

Cloning –Can we clone endangered species to rescue

them?

Not today. To do so requires an extensive knowledge of the species’ reproductive biology. We don’t have that knowledge for many (if any) endangered species.

Our knowledge of sheep reproductive biology is the reason why Dolly was the first cloning success.

Dolly

The potential for cloning from DNA extracted from non-germ cells is the reason why scientists save tissue samples from other disappearing species, e.g. the now-extinct Hawaiian honeycreeper (in Hawaiian, the po’ouli)

Tissues from this last individual were preserved in hopes that someday we may be able to restore the species using cloning technology.

Currently, 1) cloning is too expensive to be used in conservation and 2) cloning would have to find appropriate surrogate mothers, since it would be too dangerous to use the last females in a species to carry and/or parent the young.

Use of life histories-There are a number of life history characteristics that point to a vulnerability to extinction. They are essentially all characteristics of K-selected life histories:

larger bodies – a larger protected area needed for them to live in.

fewer offspring – they can’t recover from any losses quickly

longer gestation and maturation

characteristically smaller population size – can lead to higher likelihood of

inbreeding

An example of many of these problems: the Florida panther

Global climate change-Global climates have been warming, whether or not human activities have driven the change. One of the key effects of warming is alteration in the distributions of disease vectors. Here’s a table of some diseases that are likely to be affected:

Disease Vector Population Distribution at risk (x106)

Malaria mosquito 2,100 (sub)tropicsSchisosomiasis snail 600 (sub)tropicsSleeping Tsetse fly 50 African sickness tropicsDengue mosquito ? tropicsYellow fever mosquito ? tropics

Malaria has already shown climate-related increase. A1ºC increase in Rwanda in 1987 led to a 337% increase in malaria incidence. The reason: the mosquito vector, Aedes aegypti, was able to move into mountainous areas where it had never been seen before.

Models of climate change and population distribution suggest that the predicted 3ºC warming will cause 50 – 80 million new cases of malaria per year.

Is exposure limited to tropics and subtropics? No. An outbreak of hantavirus (carried by a mouse vector and spread in its poop) occurred in the southwestern U.S., killing 27, as a result of the climate warming and increased rains in the El Niño event of 1993. Without mosquito control, dengue could enter Florida today.

The maximum sustainable yield problem-

You already know the basic idea:

When harvesting occurs, we need to adjust for removal of potentially reproducing individuals. We do that, in one version of the harvested logistic, by introducing a subtractive term into the logistic…

dN

dtrN

K N

KqEN

( )

q is a ‘catch’ constant (a catch efficiency)E is fishing effort (hours spent fishing)N is the number of fish available

qE is, then, fishing mortality, separable from normal biological losses.

Before we add this term, the sustainable yield per unit time is Nr. If qEN exceeds Nr, the population declines, and the yield is not sustainable, and overfishing has occurred.

Add to this seasonal variability, Allee effect in diminished populations, variationin rates of population growth, etc. and the political inaction in the face of mounting evidence, and the disappearance of Newfoundland cod stocks becomes easy to understand.

Plant secondary chemicals and disease treatments-You’ve already heard about taxol from the Pacific yew, used in the treatment of breast cancer. Here are some other examples:

Plant Compund Use Cultivated in

Atropa belladonna atropine dilation U.S.,Europe,China

Catharanthus roseus vincristine anti-tumor pantropical

Cinchona ledgeriana quinine malaria Indomesia,Zaire

Datura matel scopalomine sedative Asia

Ephedra sinica ephedrine bronchitis China

Digitalis purpurea digitoxin heart Europe,Asia

Papaver somniferum morphine sedative Turkey,Burma

Those are a few of the important drugs we currently extract from plants. Note that a number (and others not listed) come from tropical plants. As mentioned in the last lecture, we simply don’t know what other potentially powerful drugs haven’t been discovered yet.

See “The Medicine Man” (starring Sean Connery) to get a Hollywood view of the value of tropical plants yet unnamed/discovered.

Community Ecology to evaluate impacts of Industrial Accidents-Recent crude oil spills off Newfoundland and in the Delaware River are killing birds and fouling the bottom.These are (relatively) minor spills when compared with the Exxon Valdez (1989, 11 million gallons), The Amoco Cadiz (1978, >50 million gallons) or the Torrey Canyon (1967, ~80 million gallons).

Birds die of hypothermia when their oil-coated feathers lose insulation capability. The problem carries over onto land when the carcasses wash up and are eaten by bears, otters, and eagles. Deer in Alaska ate oil-soaked kelp.

More money was spent on clean-up of the Exxon Valdez spill (~3.2 billion dollars) than the U.S. National Science Foundation gets in two centuries.

The legal question asked was whether the clean-up restored the communities so that plants and animals characteristic of the community were present and functioning normally. You should know that this ‘definition’ does not take into account population densities and demographies.

What you may find surprising is that the steam cleaning, that did remove the oil from the shoreline, actually slowed the recovery of dominant vegetation. Cold water cleaning was far less effective, but communities treated that way recovered more rapidly, and the best treatment was to leave the oiled beach alone.

Food Webs and the Trophic Transfer of Pollutants-The key points here are:

1) Most of the pollutants we are concerned about are industrial or agricultural chemicals. They are organic molecules.

2) They are relatively insoluble in water, but highly soluble in lipids. Therefore, they concentrate in the tissues of living organisms.

3) When a predator eats an organism from a lower trophic level, it takes in and accumulates the pollutants in the bodies of its prey. The predator also generally lives longer. Combining the two factors, the concentration of pollutant is many times higher in predator than prey.

4) These chemicals could (conceivably) reach a level at which literal intoxication occurred. However, most of the chemicals have physiological effects far below that.

What are some of those effects?

Estrogenic effects – a number of pollutants act like estrogens and screw up animal reproductive patterns

Developmental effects – some PCBs apparently affect brain development in young children.

Behaviour patterns and IQ scores are negatively affected.

Shell glands in fish-eating birds are affected. Eggshells are thinner, to the point where the brooding female crushes her eggs.

Bird bill development is also affected. Gulls with high contaminant levels have a much higher

frequency of young with cross bills.

A thin-shelled, crushed brown pelican egg