Descent with Modification: A Darwinian View of Life. Chapter 22. Figure 22.1 A marine iguana, well-suited to its rocky habitat in the Galápagos Islands. Marine iguana. Linnaeus (classification). Hutton (gradual geologic change). Lamarck (species can change). Malthus (population limits).
Hutton (gradual geologic change)
Lamarck (species can change)
Malthus (population limits)
Cuvier (fossils, extinction)
Lyell (modern geology)
Darwin (evolution, natural selection)
Wallace (evolution, natural selection)
U.S. Civil War
Hutton proposes his theory of gradualism.
Malthus publishes “Essay on the Principle of Population.”
Lamarck publishes his theory of evolution.
Lyell publishes Principles of Geology.
Darwin travels around the world on HMS Beagle.
Darwin begins his notebooks on the origin of species.
Darwin writes his essay on the origin of species.
Wallace sends his theory to Darwin.
TheOrigin of Species is published.
Mendel publishes inheritance papers.Figure 22.2 The historical context of Darwin’s life and ideas
(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
(b) A stick mantidin AfricaFigure 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
Pools with killifish,
but not guppies prior
Predator: Killifish; preys
mainly on small guppies
than those in
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?
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
Weight of guppies
at maturity (mg)
Age of guppies
at maturity (days)
Guppies transplanted to
pools with killifish as
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.
Human embryoFigure 22.15 Anatomical similarities in vertebrate embryos
Identical to the Amino Acids in a
Human Hemoglobin Polypeptide
LampreyFigure 22.16 Comparison of a protein found in diverse vertebrates
squirrelFigure 22.17 Different geographic regions, different mammalian “brands”