Chapter 22: Descent with Modification: A Darwinian View of Life

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

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


Figure 22.2 The historical context of Darwin’s life and ideas

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)

1750

American Revolution French Revolution U.S. Civil War1800 1850 1900

1795 Hutton proposes his theory of gradualism.

1798 Malthus publishes “Essay on the Principle of Population.”

1809 Lamarck publishes his theory of evolution.1830 Lyell publishes Principles of Geology.

1831–1836 Darwin travels around the world on HMS Beagle.

Darwin begins his notebooks on the origin of species.1837Darwin writes his essay on the origin of species.1844

Wallace sends his theory to Darwin.1858

The Origin of Species is published.1859Mendel publishes inheritance papers.1865


Figure 22.3 Fossils from strata of sedimentary rock


Figure 22.4 Acquired traits cannot be inherited


Figure 22.5 The voyage of HMS Beagle

EnglandEUROPE

NORTHAMERICA

GalápagosIslands

Darwin in 1840,after his return

SOUTHAMERICA

Cape ofGood Hope

Cape Horn

Tierra del Fuego

AFRICA HMS Beagle in port

AUSTRALIA

Tasmania

NewZealand

PACIFICOCEAN

An

des

ATLANTICOCEAN


Figure 22.6 Beak variation in Galápagos finches

(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 22.7 Descent with modification

Hyracoidea(Hyraxes)

Sirenia(Manatees

and relatives)

Ye

ars

ag

oM

illio

ns

of

yea

rs a

go

Dei

noth

eriu

m

Mam

mut

Ste

godo

n

Mam

mut

hus

Pla

tybe

lodo

n

Bar

ythe

rium

Moe

rithe

rium

Elephasmaximus

(Asia)

Loxodontaafricana(Africa)

Loxodontacyclotis(Africa)


Figure 22.8 Overproduction of offspring


Figure 22.9 Variation in a population


Figure 22.10 Artificial selection

Terminalbud

Lateralbuds

Brussels sproutsCabbage

Flowercluster Leaves

Cauliflower

Flowerandstems

Broccoli Wild mustard Kohlrabi

Stem

Kale


Figure 22.11 Camouflage as an example of evolutionary adaptation

(a) A flower mantidin Malaysia

(b) A stick mantidin Africa


Figure 22.12 Can predation pressure select for size and age at maturity in guppies?

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).

EXPERIMENT

Pools with killifish,but not guppies priorto transplant

Experimentaltransplant ofguppiesPredator: Killifish; preys

mainly on small guppies

Guppies:Larger atsexual maturitythan those in“pike-cichlid pools”

Predator: Pike-cichlid; preys mainly on large guppies

Guppies: Smaller at sexual maturity thanthose in “killifish pools”


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.

161.5185.6

67.5

Wei

ght

of g

upp

ies

at m

atur

ity (

mg)

Age

of

gupp

ies

at m

atur

ity (

days

)

92.3

48.5

Control Population: Guppiesfrom pools with pike-cichlids as predators

Experimental Population:Guppies transplanted topools with killifish aspredators

76.1

Males Females

85.7

58.2

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.


Figure 22.13 Evolution of drug resistance in HIV

PatientNo. 1

Patient No. 2

Patient No. 3

Per

cen

t of

HIV

res

ista

nt

to 3

TC

Weeks


Figure 22.14 Mammalian forelimbs: Homologous structures

Human Cat Whale Bat


Figure 22.15 Anatomical similarities in vertebrate embryos

Pharyngealpouches

Post-analtail

Chick embryo Human embryo


Figure 22.16 Comparison of a protein found in diverse vertebrates

Species

Human

Rhesus monkey

Mouse

Chicken

Frog

Lamprey14%

54%

69%

87%

95%

100%

Percent of Amino Acids That AreIdentical to the Amino Acids in aHuman Hemoglobin Polypeptide

Chapter 22: Descent with Modification: A Darwinian View of Life

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