Reduction in Biological Diversity Section 4.1 p. 57-65 Section 4.3 p. 72-78
Review Ecological Diversity A variety of ecosystems (mountains, forests, deserts) and how they interact together. Community Diversity Different species (populations) interacting in one area. Genetic Diversity Differences (variation) within one species. Biological Diversity The variation in living things.
Extinction This means that every individual of a particular species has disappeared from the entire planet. This is a natural part of life on Earth. Most mass extinctions, like the one that killed the dinosaurs, were likely caused by a catastrophic event (like an earthquake or volcano). The last major environmental change that created a mass extinction was 1.8 million years ago. You might know this time as the Ice Age.
Most extinctions Most extinctions are not mass extinctions. They happen over long periods of time. Scientists think that the rate at which these species are becoming extinct is increasing. More species will become extinct in this decade than the decade before. So biological diversity is decreasing more rapidly than ever before.
Human Causes of Extinction Today, most extinction and extirpation is caused by human activity. Occurs due to: Habitat Destruction Introduction of Non-Native Species Over-Hunting
Habitat Destruction How can humans change a habitat of another species? Construction, agriculture, logging, damming rivers. While these are important for human survival, we still need to be aware of the effects we are having on other species. The Albertan prairies are only of the most affected land sites because it was the best for farming. Only 20% (and maybe less) of Alberta s prairies remain in natural condition.
Pollution is another source of habitat destruction. This is particularly harmful because pollution can affect a large area. Pesticides, herbicides and fertilizers not only affect the area where they are used but they also get washed into water systems and get carried to other ecosystems. These chemicals often have a negative effect on aquatic life. Many fish, frogs and toads offspring are developing birth defects because of these chemicals.
Introduction of Non-Native Species When introduced species use the same resources as native species. This results in Interspecies Competition For example: Horses and cattle were not in America until the Europeans arrived. Many plant species grow rapidly and outcompete native plants because they usually have no natural predators. The Dodo was a flightless bird that lived on an island near the Indian Ocean. It had no natural predators. Explorers soon discovered the island where the Dodo lived and when they landed on the island in 1505 they brought with them cats, dogs, rats and pigs. These animals ate the Dodo s eggs and sailor s landing on the island ate the adult Dodo as food. By 1681, the Dodo had become extinct only 200 years after first human contact
Over-Hunting This is one of the main reasons for the extinction of passenger pigeons. Flocks of passenger pigeons were so large in the 19 th century that people reported not being able to hear the gunshot when they flew overhead. They were mostly hunted for sport. This resulted in a rapid decline of the species as the sport became more popular. The last passenger pigeon died on September 1, 1914.
Over hunting is also the reason for the extirpation (and almost the extinction) of the plains bison. They were hunted for food and their bones were used as fertilizer for farmers. In 1888, there were only 8 Plains Bison in Canada and 85 in all of North America. Today, they are only listed as threatened on the Canadian endangered wildlife list.
Extirpation This is a local extinction of a species from a particular area. The grizzly bear for example used to be plentiful in British Columbia, where there was lots of fish, plants and small animals on which to feed. Grizzlies are now mainly found in the mountains. Urbanization, road building and other activities have limited them to this area. What happens when an animal moves from one ecosystem to another? The woodland caribou is currently at risk from being extirpated from the boreal forests of Northern Alberta. The swift fox was once common in Alberta but by 1928, the species was complete extirpated from Canada. Most of these extirpations result from habitat degradation from logging, forest fires and increased interspecies competition. What could be a cause of increased interspecies competition?
Natural Causes of Extirpation We have learned that through sexual reproduction, a species can have increased variation which leads to increased ability to survive environmental change. But sometimes, regardless of variability, species still disappear. For example, dinosaurs were once the most successful species on Earth but they all disappeared 65 million years ago. Most of the time this is from: Catastrophic event (flood, volcano eruption or fires) Lack of food from overpopulation. Disease
Overspecialization Sometimes organisms have adapted to a narrow range of environment. This usually happens if the environment in an area has not changed for an very long time. If there is little change, then the individuals in that area have little adaptation. Why change if you don t have to, right? Then the environment might change and these specialized animals can die off because they cannot handle the change.
Overspecialization a natural cause of extinction An example of overspecialization The Giant Panda: It eats only one thing, bamboo shoots. Because they have specialized to only eat bamboo, it cannot switch to a different source of food. Bamboo forests sometimes get cut down or die off. So although Panda s food source is decreasing, their overspecialization in eating only bamboo is threatening their survival.
The Effects Extirpation and extinction reduce biological diversity because the decrease the amount of species on the planet. How can a species disappearing locally or globally affect other species? Prairie dogs have been extirpated from Canada because they were annoying to farmers. In the 1930 s there was an extensive poisoning campaign to get rid of prairie dogs. Prairie dogs were a major food source for black-footed ferrets. Black-footed ferrets are now one of the most endangered species in North America.
Reducing Our Impact on Bio Diversity At an Earth summit in Rio de Janeiro in 1992 World leaders signed a treaty called the United Nations Convention on Biological Diversity It outlined three main goals to maintaining biological diversity Conservation of Biological Diversity Sustainable use of the components of biological diversity Fair and equitable sharing of the benefits of genetic resources
Strategies to Conserve Biological Diversity Protected Areas: In-situ Conservation (refers to the maintenance of populations of wild organisms in their functioning ecosystems, allowing ecological processes to continue undisturbed) i.e. National Park Restoration of Ecosystems and Species Canada has developed various programs to restore endangered species and damaged habitats Charities, Not-for-Profit organizations, volunteer groups and private landowners contribute land to allow species to live in natural areas (or be reintroduced) Ducks Unlimited buys wetlands from farmers to protect birds breeding grounds. Ann and Sandy Cross donated 1943 ha - one of the largest private land donations ever in North America. Landowners returning a portion of their land to its natural state
Resource use Policies Federal and Provincial governments have laws that protect species that are endangered laws (1994) to protect species of organisms endangered Provinces have agreed to pass more localized laws dealing with: Endangered organisms Use of land and resources Alberta passed its legislation in 1998 Purple Loosestrife brought in from Europe and has no natural enemies here in NA. Therefore it runs ramped taking over wetlands. Groups go in to remove it and burn it Conservation of Genetic Resources Ex-situ Conservation: conservation of components of biodiversity outside its natural habitat. (storing of genetic variation of species) plays vital role in that it is often the last chance for endangered species Seed banks: Canada is responsible for barley and oats for the entire world (Plant Gene Resources of Canada)