Chapter 22: Descent with Modification: A Darwinian View of Life
Figure 22.1 A marine iguana, well-suited to its rocky habitat in the Galápagos Islands
Linnaeus (classification) Hutton (gradual geologic change) Lamarck (species can change) Malthus (population limits) Cuvier (fossils, extinction) Lyell (modern geology) Darwin (evolution, natural selection) Mendel (inheritance) Wallace (evolution, natural selection) American Revolution French Revolution U.S. Civil War 1800 1850 1900 1750 1795 Hutton proposes his theory of gradualism. 1798 Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution. Lyell publishes Principles of Geology. 1830 Darwin travels around the world on HMS Beagle. 1831–1836 1837 Darwin begins his notebooks on the origin of species. 1844 Darwin writes his essay on the origin of species. 1858 Wallace sends his theory to Darwin. TheOrigin of Species is published. 1859 1865 Mendel publishes inheritance papers. Figure 22.2 The historical context of Darwin’s life and ideas
England EUROPE NORTH AMERICA ATLANTIC OCEAN PACIFIC OCEAN Galápagos Islands HMS Beagle in port AFRICA SOUTH AMERICA Darwin in 1840, after his return AUSTRALIA Cape of Good Hope Andes Tasmania Cape Horn New Zealand Tierra del Fuego Figure 22.5 The voyage of HMS Beagle
(a) Cactus eater. The long,sharp beak of the cactusground finch (Geospizascandens) helps it tearand eat cactus flowersand pulp. (c) Seed eater. The large groundfinch (Geospiza magnirostris)has a large beak adapted forcracking seeds that fall fromplants to the ground. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses itsnarrow, pointed beak to grasp insects. Figure 22.6 Beak variation in Galápagos finches
Sirenia (Manatees and relatives) Loxodonta cyclotis (Africa) Elephas maximus (Asia) Loxodonta africana (Africa) Hyracoidea (Hyraxes) Years ago Stegodon Mammut Mammuthus Deinotherium Platybelodon Millions of years ago Barytherium Moeritherium Figure 22.7 Descent with modification
Lateral buds Terminal bud Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Stem Flower and stems Broccoli Wild mustard Kohlrabi Figure 22.10 Artificial selection
(a) A flower mantidin Malaysia (b) A stick mantidin Africa Figure 22.11 Camouflage as an example of evolutionary adaptation
Reznick and Endler transplanted guppies from pike-cichlid pools to killifish pools and measured the average age and size of guppies at maturity over an 11-year period (30 to 60 generations). Pools with killifish, but not guppies prior to transplant Experimental transplant of guppies EXPERIMENT Predator: Killifish; preys mainly on small guppies Guppies: Larger at sexual maturity than those in “pike-cichlid pools” Predator: Pike-cichlid; preys mainly on large guppies Guppies: Smaller at sexual maturity than those in “killifish pools” Figure 22.12 Can predation pressure select for size and age at maturity in guppies?
RESULTS After 11 years, the average size and age at maturity of guppies in the transplanted populations increased compared to those of guppies in control populations. Control Population: Guppies from pools with pike-cichlids as predators 185.6 92.3 85.7 161.5 Weight of guppies at maturity (mg) Age of guppies at maturity (days) 58.2 48.5 76.1 67.5 Experimental Population: Guppies transplanted to pools with killifish as predators Males Females Males Females CONCLUSION Reznick and Endler concluded that the change in predator resulted in different variations in the population (larger size and faster maturation) being favored. Over a relatively short time, this altered selection pressure resulted in an observable evolutionary change in the experimental population.
Patient No. 1 Patient No. 2 Percent of HIV resistant to 3TC Patient No. 3 Weeks Figure 22.13 Evolution of drug resistance in HIV
Human Cat Bat Whale Figure 22.14 Mammalian forelimbs: Homologous structures
Pharyngeal pouches Post-anal tail Chick embryo Human embryo Figure 22.15 Anatomical similarities in vertebrate embryos
Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide Species 100% Human Rhesus monkey 95% Mouse 87% Chicken 69% Frog 54% 14% Lamprey Figure 22.16 Comparison of a protein found in diverse vertebrates