BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 14 The Origin of Species Modules 14.1 – 14.2

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Evolution has generally been thought of as a very gradual process –However, examples of rapid evolution have been observed Evolution Underground

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings One example of rapid evolution occurred among mosquitoes who migrated into the London underground In less than 150 years, Culex pipiens evolved into a new mosquito species, Culex molestus The origin of new species is called speciation

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The isolated mosquitoes adapted to their new underground environment –They altered their prey, mating habits, and breeding patterns Environmental barriers that isolate populations are just one of many mechanisms in the evolution of species

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Linnaeus used physical appearance to identify species when he developed the binomial system of naming organisms –This system established the basis for taxonomy 14.1 What is a species? CONCEPTS OF SPECIES

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings But appearance alone does not always define a species Figure 14.1A –Example: eastern and western meadowlarks

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Similarities between some species and variation within a species can make defining species difficult –Humans exhibit extreme physical diversity Figure 14.1B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The biological species concept defines a species as –a population or group of populations whose members can interbreed and produce fertile offspring

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A ring species may illustrate the process of speciation Figure 14.1C OREGON POPULATION 1 2 COASTAL POPULATIONS Yellow- eyed Monterey 3 Sierra Nevada Yellow- blotched Gap in ring Large- blotched INLAND POPULATIONS

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The biological species concept is not applicable to fossils or asexual organisms Most organisms are classified based on observable and measurable phenotypic traits. The morphological species concept Even with most living, sexually reproducing species, we lack sufficient information about interbreeding to use reproductive isolation as the sole criterion for species assignments.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Other Species Concepts: The genealogical species concept defines a species as a cluster of organisms representing a specific evolutionary lineage-with a unique genetic history-using molecular data The ecological species concept defines a species by its ecological role-or ecological niches-their particular roles in a biological community.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prezygotic and postzygotic reproductive barriers prevent individuals of different species from interbreeding 14.2 Reproductive barriers keep species separate Table 14.2

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Courtship ritual in blue-footed boobies is an example of one kind of prezygotic barrier, behavioral isolation Many plant species have flower structures that are adapted to specific pollinators –This is an example of mechanical isolation, another prezygotic barrier Figure 14.2A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Hybrid sterility is one type of postzygotic barrier –A horse and a donkey may produce a hybrid offspring, a mule –Mules are sterile Figure 14.2C