13.1 What Is Biotechnology? Biotechnology is the use, and especially the alteration, of organisms, cells, or biological molecules to produce food, drugs, or other goods – Traditional applications of biotechnology include the use of yeast to make bread, beer, and wine, and the selective breeding of animals

13.1 What Is Biotechnology? More modern uses modify the genes directly through genetic engineering – A relatively familiar application of biogenetic engineering is cloning, which is used to make identical copies of individual genes or even entire organisms – A key tool of genetic engineering is recombinant DNA, which is DNA that has been altered to contain genes or portions of genes from different organisms – Plants and animals that express DNA that has been modified or derived from other species are transgenic or genetically modified organisms (GMOs)

Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859 Darwin made two main points: – Species showed evidence of “descent with modification” from common ancestors – Natural selection is the mechanism behind “descent with modification” Darwin’s theory explained the duality of unity and diversity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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Darwin observed that: – Individuals in a population have traits that vary – Many of these traits are heritable (passed from parents to offspring) – More offspring are produced than survive – Competition is inevitable – Species generally suit their environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Darwin inferred that: – Individuals that are best suited to their environment are more likely to survive and reproduce – Over time, more individuals in a population will have the advantageous traits In other words, the natural environment “selects” for beneficial traits Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig Population with varied inherited traits. Elimination of individuals with certain traits. Reproduction of survivors. Increasing frequency of traits that enhance survival and reproductive success

Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species – For example, the finch species of the Galápagos Islands Evolutionary relationships are often illustrated with tree-like diagrams that show ancestors and their descendents Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig COMMON ANCESTOR Warbler finches Insect-eaters Seed-eater Bud-eater Insect-eatersTree finches Green warbler finch Certhidea olivacea Gray warbler finch Certhidea fusca Sharp-beaked ground finch Geospiza difficilis Vegetarian finch Platyspiza crassirostris Mangrove finch Cactospiza heliobates Woodpecker finch Cactospiza pallida Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Large cactus ground finch Geospiza conirostris Cactus ground finch Geospiza scandens Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris Ground finches Seed-eaters Cactus-flower- eaters

15.2 What Causes Evolution? Mutations are the original source of genetic variability – A population remains in evolutionary equilibrium only if there are no mutations (changes in DNA sequence) Most mutations occur during cell division, when a cell makes a copy of its DNA Inherited mutations are rare but important – The cumulative effect of mutations is essential to evolution