Transcript lesson3
Endangered Species Lesson 3 November 16, 2010 wiki Frogs aren’t the only things disappearing from our ecosystems! Classifying Species at Risk EXTINCT • A species that is no longer found anywhere Classifying Species at Risk ENDANGERED • A species that is close to extinction in all parts of Canada or in a significantly large location Classifying Species at Risk EXTIRPATED • Any species that no longer exists in one part of Canada, but can be found in another Classifying Species at Risk THREATENED • Any species that is likely to become endangered if factors that make it vulnerable are not reversed Classifying Species at Risk VULNERABLE • Any species that is at risk because of low or declining numbers at the fringe of its range or in some restricted area How at risk am I? Atlantic Walrus • There are several thousand in Canadian waters, but one population (the Northwest Atlantic) no longer exist How at risk am I? Beluga Whale • Excessive hunting, water pollution and high water traffic are factors that if not reversed will lead to extinction. How at risk am I? Atlantic Salmon • Populations have declined by 90% or more in recent years. How at risk am I? Blue Walleye • The last species of this fish was taken from Lake Erie in 1965. How at risk am I? Smallmouth Salamander • The loss of breeding grounds and a decrease in water levels from March through July are among the factors limiting populations. Extinction in the Modern World • In 1850’s passenger pigeons filled the skiesone scientist saw a flock that he estimated had 2 billion birds! • By 1914 there wasn’t a single passenger pigeon anywhere on Earth • Commercial hunting and the clearing of forests were both to blame • Passenger pigeons were easy to kill Humans and the Rate of Extinction • Passenger pigeons are not the only organisms to go extinct • Humans have had a profound effect on other organisms • Species extinction rates are increasing dramatically as human populations grow • Between 8000 BC and 1600 AD extinction rates were estimated at one species every 1000 years • Between 1600 and 1900 the estimate is one species went extinct every 4 years • We now estimate that 80 species go extinct per year A Brief History of Extinction • 438 million years ago- mass extinction of marine organisms (glaciation) • 360 mya- another mass extinction of marine organisms (glaciation and meteorite impact) • 245 mya- largest mass extinction- about 80% of all species (glaciation and volcanism) • 208 mya- 35% of all families die out • 65 mya- the end of the age of the dinosaurs (asteroid impact) The Crater from 65 MYA 9.6 km deep and 300 km wide Other Causes • Earth has housed nearly 500 million different species, but 90% have either become extinct or evolved into a new species • Climate changes and pressure of competition force organisms to adapt or die • If a new species comes into an area, species that eat the same foods must compete with it and the species that is better and stronger could force the other species into extinction • The extinction of that species could affect other species that rely on it for food • In modern times, human activities are the major causes of extinction Effects of Extinction • Domino Effect- because all organisms in an ecosystem are connected the reduction in biodiversity caused by the extinction of one species effect all species • Biodiversity- number of species in an ecosystem Restoring the Balance • Reintroduction is not easy to do. • Whooping crane-success story • Fly north in Spring to live in Northern Canada and the prairies • In 1940 there were only 14 individuals • In 1999 there were 183 • Relationships in an ecosystem cannot be completely understood, therefore we cannot reliably predict what will happen to an ecosystem if its biodiversity is reduced. • An extinction of even just one species could e disastrous and we would not know the extent until later (“you don’t know what you’ve got til it’s gone”) Assignment Textbook page 15 Understanding Concepts Do question 2 a b and c Hand in when done