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 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 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 –King: Kingdom –Philip: Phylum –Cried: Class –Out: Order –For: Family –Good: Genus –Soup: Species 14.1 What is a species? CONCEPTS OF SPECIES

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 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 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 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 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 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 Adaptive radiation is when numerous species evolve from a common ancestor due to new environments Islands are living laboratories of speciation 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 In sympatric speciation, a new species may arise without geographic isolation –This is usually caused by spontaneous genetic mutation 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