Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint® Lectures Lectures by Chris Romero, Front Range Community College On the Termination of Species Current Issues in Biology, Volume 1 Scientific American

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Concept Review Oxford zoologist Robert M. May and other scientists claim that humans could be causing the sixth great wave of mass extinctions on Earth. May estimates that the extinction rate of organisms on Earth has accelerated during the past 100 years to roughly 1,000 times what it was before humans showed up.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Concept Review Most scientists identify five major mass extinctions in Earth’s history. A mass extinction is any set of events that leads to the extinction of a significant number of species.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Concept Review Some scientists dispute the claim that the Earth is currently experiencing a mass extinction event-this time, caused by humans. These scientists have reported that the methods used to calculate extinction rates are flawed by false assumptions.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Two factors that compound the problem of estimating extinction are 1.The enormous number of species on the Earth 2.Many of those species are not yet identified. Concept Review

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Habitat loss due to human development has long been thought to contribute to extinction (the “species- area relation”), but recent data has also proven inconclusive. Concept Review

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Concept Review However, annual forest loss has declined somewhat in recent years. Although projections of extinction rates have been inconsistent, biology have good reasons to fear that if a mass extinction hasn’t begun yet, it is imminent.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Concept Review A goal of many scientists has been to promote the importance of species and habitat conservation. Edward O. Wilson, a Harvard professor states, “It turns out to be a lot easier to persuade a corporate CEO or a billionaire of the importance of the issue than it is to convince the American public.”

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species How many mass extinctions are known from the fossil record? a) 1 b) 5 c) 11 d) 46 Testing Your Comprehension

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Testing Your Comprehension How many mass extinctions are known from the fossil record? b) 5

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Which kind of organism comes in more species that the total species of all the other multicellular organisms combined? a) Insects b) Fungi c) Nematodes d) Protozoa Testing Your Comprehension

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Testing Your Comprehension Which kind of organism comes in more species that the total species of all the other multicellular organisms combined? a) Insects

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species What does the “species-area relation” say about the relationship between habitat loss and species extinction? a) As habitat area is lost, the number of species living in it decreases. b) As habitat area is lost, the number of species living in it increases. c) As habitat area is lost, the number of species living in it does not change. d) As habitat area is gained, the number of species living in it decreases. Testing Your Comprehension

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Testing Your Comprehension What does the “species-area relation” say about the relationship between habitat loss and species extinction? a) As habitat area is lost, the number of species living in it decreases.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Given that estimates of extinction rates are uncertain, do you think it is a good idea to base public policies on the assumption that species are, in fact, disappearing at an increasing rate? Strongly Agree Strongly Disagree A. E. C. B. D. Biology In Society

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Which of the following is NOT a common argument made by conservationists in favor of maintaining species diversity? a)Most of our drugs are derived from natural species. b)Whole ecosystems provide irreplaceable services to the biosphere. c)Humans have a moral obligation to act as stewards for the diversity of life. d)Human nutrition depends upon having a wide variety of natural species to eat. Thinking About Science

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Thinking About Science Which of the following is NOT a common argument made by conservationists in favor of maintaining species diversity? d)Human nutrition depends upon having a wide variety of natural species to eat.

Copyright © 2006 Pearson Education, Inc. publishing as Benjamin Cummings On the Termination of Species Thinking About Science Scientists often become advocates for conservation. How might advocacy for a cause such as conservation lead to bias in the research related to the so-called biodiversity crisis?