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Human Activity affects biological diversity. Key Concepts. Biological Diversity Species Habitat Diversity Natural & Artificial selection of genetic characteristics . First a review…. Dominant & Recessive Traits
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Key Concepts • Biological Diversity • Species • Habitat Diversity • Natural & Artificial selection of genetic characteristics
First a review… • Dominant & Recessive Traits • Punnit Square: a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach, and is used by biologists to determine the probability of an offspring's having a particular genotype.
Reduction of Biological Diversity • Balancing human needs with the needs of other organisms is often very difficult. • Because we want lots of STUFF!! Land to grow our food, land to build our houses and malls, and we all (or at least most of us) want more $$$$! • It all comes down to choices…
Species and ecosystems on Earth, and the ecological processes of which they are part of (like photosynthesis, cellular respiration, water cycle, carbon cycle) are stressed by: • Urbanization • Expansion of human industries such as agriculture and forestry.
Resulting decline in genetic, species & ecosystem diversity… • Threatens the ecological, economic, and cultural benefits we currently get from Earth’s living resources. • The extinction of some species, the decrease in population of other species, and the degradation of ecosystems reduces biological diversity on Earth.
Mauritius… 1505 • Dodo had no natural predators on the island. • Humans land bringing cat, rats, dogs and pigs. • The introduced animals ate the Dodo bird eggs as food, and humans ate the adult Dodo. • Within 200 years of first human contact, the Dodo was extinct (probably around 1681).
Extinction & Extirpation • The disappearance of every individual of a species from the entire planet is called extinction. • Natural part of Earth’s history. Scientists estimate that 99% of all the species that have ever existed are now extinct. • Mass extinctions, like the one that killed off all of the dinosaurs, have probably been caused by catastrophic events.
Most extinctions are not mass extinctions, and take place over longer periods of time. • Scientists believe that the rate at which species are going extinct is increasing. • Mores species will disappear over the next decade than disappeared over the last decade (10 years), so the biological diversity of the planet is decreasing more and more rapidly.
Local extinction, or the disappearance of a species from a particular area is called extirpation. • The Grizzly bear was once found all over our area, from the mountains of B.C. to the prairies of Manitoba. • They had a rich supply of fish, small mammals, and plants on which to feed.
Urbanization, road building, and other activities related to the search for natural resources, such as oil and gas, have impacted the Grizzly’s range • Grizzlies are now found mainly in the mountains. • Woodland Caribou are currently at risk of being extirpated from the boreal forests of Northern Alberta because they are losing habitat due to logging, forest fires, and increased interspecies competition.
What does the fox say? Help me… I have no where to live and farmers are killing me!!! • Swift Fox… once common in Alberta, but by 1928 the species was completely extirpated from Canada. • A major breeding program is under way in a partnership between groups such as the World Wildlife Fund, and the Alberta Department of Environmental Protection to reintroduce the fox to Alberta.
At Risk Species in Alberta • Read over the chart on page 59… there could be a question on the PAT.
Natural Causes • Natural Selection is a slow process. Sometimes even if there is a lot of variation within a species, sometimes the environment changes too much, too quickly for a species to survive. • E.g. Dinosours… Although contained great variety and were very successful, disappeared about 65 million years ago. • In the past, most extinctions and extirpations due to natural were due to natural causes such as: • Catastrophic events- volcanic eruptions, floods, fires • Lack of food due to overpopulation • Disease
Not all extinctions happened a long time ago… • 1904, the chestnut blight, a disease caused by fungus, appeared in American chestnuts found in New York City. • The fungus came from Asia and spread quickly to North American trees which had little resistance. • By 1950, the species had essentially disappeared. • Attempts are continuing to create a blight-resistant strain in order to bring this species back from the edge of extinction.
Overspecialization • Sometimes organisms have adaptations that suit them to only a narrow set of environmental conditions. • This probably happens because the environment that the organism lives in has remained unchanged for a long time. • Biologists call this overspecialization. • Overspecialization is another cause of extinction.
Eats only one thing… bamboo shoots, and cannot switch to other sources of food. • Bamboo forests are in short supply… sometimes they die off (disease, environmental conditions), and sometimes are cut down for human needs. • The panda’s overspecialization makes them very vulnerable to extinction.
Human causes of extinctions & extirpations • Today, most extinctions and extirpations are due to human activity. • Human populations continue to grow, and require more land for houses and food- human activity is not the leading cause of worldwide species loss.
Habitat Destruction • Human construction of buildings, agricultural development, logging, and the damming of rivers all change environments. • In Canada, only 20% of the area once covered by native prairie species is still in its natural state- grasslands provided the best farm sites, so the land was cleared. • Pollution is a particular kind of habitat destruction.
It affects not only the immediate area, but often areas farther away. • Pesticides, herbicides and fertilizer used in farming can be washed into nearby water supplies and cause the death of native species. • Pollution of breeding sites is the main cause of the dramatic reduction of the great plains toad in Alberta, which is now in the “Special Concern” category.
Introduction of Non-Native Species • Throughout history humans have migrated, and carried with them many species on which they relied. • The corn that First Nations grew at the time of European settlement was originally brought from South America. Europeans brought horses and cattle with them to North America. • When introduced species use the same resources as native species, they compete and cause the number of native species to decline, simply because they get less of everything.
Cattle now graze where bison once roamed… • Attempts to reintroduce Bison are limited by competition for grazing resources.
What are some other ways non-native species are introduced to an area?
Over Hunting • The last passenger pigeon died in captivity on September 1, 1914. • They were hunted mainly for sport, and the sport was very popular. • One flock in 1866 in southern Ontario was described as being 1 mi (1.5 km) wide and 300 mi (500 km) long, took 14 hours to pass, and held in excess of 3.5 billion birds • People at the time reported being unable to even hear gunshots when they flew overhead.
Sometimes species were hunted deliberately to extirpate them- people found them to be a pest. • Black-tailed prairie dogs were considered a menace to farmers and ranchers because they ate grain and dug holes causing cattle and horses to break legs. • In the 1930s, large scale poisoning campaigns reduced prairie dog numbers.
Effects of extinctions & extirpations • Both reduce biological diversity. • When an organism disappears locally or globally, many other species are affected. • E.g. In regions where black-tailed prairie dogs were extirpated, burrowing owls and black footed ferrets were also affected. Prairie dogs were the major source of food for black-footed ferrets and burrowing owls used abandoned burrows as nesting sites. • Black-footed ferrets are now one of the most endangered species in North America.
