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 SSHS AP Biology

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 phenotypes –The morphological species concept The genealogical species concept defines a species as a cluster of organisms representing a specific evolutionary lineage The ecological species concept defines a species by its ecological role

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

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings When a population is cut off from its parent stock, species evolution may occur –An isolated population may become genetically unique as its gene pool is changed by natural selection, genetic drift, or mutation –This is called allopatric speciation 14.3 Geographic isolation can lead to speciation MECHANISMS OF SPECIATION Figure 14.3

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings On the Galápagos Islands, repeated isolation and adaptation have resulted in adaptive radiation of 14 species of Darwin’s finches 14.4 Islands are living laboratories of speciation Figure 14.4A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Adaptive radiation on an island chain Figure 14.4B Species A from mainland 1 A 2 B B 3 B C 4 C C 5 B C D C D

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In sympatric speciation, a new species may arise without geographic isolation –A failure in meiosis can produce diploid gametes –Self-fertilization can then produce a tetraploid zygote 14.5 New species can also arise within the same geographic area as the parent species Figure 14.5A Parent species 2n = 6 Diploid Unreduced diploid gametes 4n = 12 Tetraploid Zygote Meiotic error Self- fertilization Offspring may be viable and self-fertile

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Sympatric speciation by polyploidy was first discovered by Dutch botanist Hugo de Vries in the early 1900s Figure 14.5B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Many plants are polyploid –They are the products of hybridization –The modern bread wheat is an example 14.6 Connection: Polyploid plants clothe and feed us Figure 14.6A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The evolution of wheat Figure 14.6B AABB Wild Triticum (14 chromo- somes) Triticum monococcum (14 chromosomes) Sterile hybrid (14 chromosomes) AB Meiotic error and self-fertilization AABBDD Sterile hybrid ABD T. turgidum EMMER WHEAT (28 chromosomes) T. tauschii (wild) (14 chromosomes) AA BB DD T. aestivum BREAD WHEAT (42 chromosomes) Meiotic error and self-fertilization

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings This has been documented by –laboratory studies (fruit flies) 14.7 Reproductive barriers may evolve as populations diverge Figure 14.7A Starch medium Initial sample of fruit flies Maltose medium Results of mating experiments Female StarchMaltose Male Starch Maltose Mating frequencies in experimental group Female populations SameDifferent Male populations Same Different Mating frequencies in control group

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –examples in natural populations (pupfish in Death Valley) Figure 14.7B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings According to the gradualist model of the origin of species –new species evolve by the gradual accumulation of changes brought about by natural selection However, few gradual transitions are found in the fossil record 14.8 The tempo of speciation can appear steady or jumpy Figure 14.8A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The punctuated equilibrium model suggests that speciation occurs in spurts –Rapid change occurs when an isolated population diverges from the ancestral stock –Virtually no change occurs for the rest of the species’ existence Figure 14.8B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The occasional hybridization of finch species adds to the genetic variation of parent populations –This may have been important in the adaptive radiation of finch species 14.9 Talking About Science: Peter and Rosemary Grant study the evolution of Darwin’s finches Figure 14.9