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BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor CHAPTER 14 The Origin of Species Modules 14.1 – 14.2 From PowerPoint® Lectures for Biology: Concepts & Connections Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The origin of species – A species is a group of organisms able to successfully breed and produce fertile offspring. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings CONCEPTS OF SPECIES 14.1 What is a species? • Linnaeus used physical appearance to identify species when he developed the binomial system of naming organisms – This system established the basis for taxonomy, animal classification Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings – King: Kingdom – Philip: Phylum – Cried: Class – Out: Order – For: Family – Good: Genus – Soup: Species Human Taxonomy • Kingdom: Animalia • Phylum: Chordata • Class: Mammalia • Order: Primate • Family: Hominidae • Genus: Homo • Species: sapiens Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings • Every living thing has a scientific name, given through binomial nomenclature, that is made up of its genus and species names. • Humans: Homo sapiens • Dogs: Canis familiaris • Wolves: Canis lupus • Cats: Felis catus Figure 14.1A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 14.2 Reproductive barriers keep species separate • Prezygotic and postzygotic reproductive barriers prevent individuals of different species from interbreeding Table 14.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prezygotic Barriers: Egg and sperm never meet • Temporal isolation: two species breed at different times of the year • Habitat Isolation: two species live in the same area but in different kinds of places (near the coast or inland in desert regions) • Behavioral isolation: mating behavior of males does not attract females of another species • Mechanical isolation: male and female sex organs don’t work together (mostly in plants) • Gametic isolation: gametes cannot unite and form a zygote Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Postzygotic barriers: babies don’t work • Hybrid inviability: hybrid zygotes either don’t develop or die too young to reproduce • Hybrid sterility: hybrids are sterile (mules) • Hybrid breakdown: offspring produced by hybrids are weak or infertile (ligers) Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings MECHANISMS OF SPECIATION 14.3 Geographic isolation can lead to speciation • How do new species evolve? – 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 Figure 14.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 14.4 Islands are living laboratories of speciation • On the Galápagos Islands, repeated isolation and adaptation have resulted in adaptive radiation of 14 species of Darwin’s finches • Adaptive radiation is when numerous species evolve from a common ancestor due to new environments. Figure 14.4A Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Peter and Rosemary Grant • Studied finches on the Galapagos for 30 years • Observed the evolution of a new species of finch through natural selection • Showed that evolution can happen both rapidly and slowly depending on environmental stresses Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 14.5 New species can also arise within the same geographic area as the parent species • In sympatric speciation, a new species may arise without geographic isolation – This is usually caused by spontaneous genetic mutation. Parent species Zygote Meiotic error Selffertilization 2n = 6 Diploid Offspring may be viable and self-fertile 4n = 12 Tetraploid Unreduced diploid gametes Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 14.5A