Varieties of life forms

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– Varieties of life forms

Figure 1.4C-F

• All organisms have evolutionary adaptations– Inherited characteristics that enhance their

ability to survive and reproduce

• blue-footed booby

• Large, webbed feet help propel the bird throughwater at high speeds

Clown, Fool, or Well Adapted?

– A streamlined shape, large tail, and nostrils that close are useful for diving

– Specialized salt-secreting glands manage salt intake while at sea

• Charles Darwin synthesized the Theory of Evolution by natural selection– Theory vs hypothesis

• Evolution is the core theme of biology

Evolution explains the unity and diversity of life

Figure 1.6A

• The voyage of the Beagle

Figure 13.1B

NorthAmerica

Great Britain Europe

Africa

Equator

Australia

Tasmania

NewZealand

Cape ofGood Hope

SouthAmerica

Cape Horn

Tierra del Fuego

GalápagosIslands

PacificOcean

AtlanticOcean

• species are fixed

• Earth is about 6,ooo yrs old

Prevalent ideas at Darwin’s time

New ideas proposed• Fossils indicated the earth was very

• Lyell, a geologist, argued that land forms changed constantly.

• Lamarck proposed that organisms changed and these changes were passed to progeny.

• While on the voyage of the HMS Beagle in the 1830s, Charles Darwin observed

– similarities between living and fossil organisms– the diversity of life on the Galápagos Islands, such as

blue-footed boobies and giant tortoises

Figure 13.1A

• Darwin became convinced that the Earth was old and continually changing

– He concluded that living things also change, or evolve over generations

– He also stated that living species descended from earlier life-forms: descent with modification

• Mex. marine snail shells on high mtns

• Darwin observed that

– organisms produce more offspring than the environment can support

– organisms vary in many characteristics

– these variations can be inherited

Darwin proposed natural selection as the mechanism of evolution

• Darwin concluded that individuals best suited for an environment are more likely to survive and reproduce than those less well adapted

– As a result, the proportion of individuals with favorable characteristics increases

– Populations gradually change in response to the environment

• natural selection explains the mechanism of evolution

Figure 1.6B

(1) Population with varied inherited traits

(2) Elimination of individuals with certain traits

(3) Reproduction of survivors

Pesticide-resistant insects

Antibiotic-resistant bacteria

• Charles Darwin, 1874

Figure 13.1x2

• Alfred Wallace

Figure 13.1x6

• Darwin cartoon

Figure 13.1x3

• Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the reproductive success of some individuals over others

– Natural selection is the editing mechanism

– Evolution is based on adaptations

Figure 1.6C

– Hominid skull

Fossils provide strong evidence for evolution

Figure 13.2A, B

– Petrified trees

– Ammonite casts

– Fossilized organic matter in a leaf

Figure 13.2C, D

– Scorpion in amber

– “Ice Man”– acid bogs

Figure 13.2E, F

• Mammoth tusks

Figure 13.2x4

• fossils show that organisms have appeared in a historical sequence

• Many fossils link early extinct species with species living today– hind leg bones of

fossil whales

Figure 13.2G, H

– Biogeography– Comparative

anatomy– Comparative

embryology

Other evidence for evolution

Figure 13.3A

Human Cat Whale Bat

– Molecular biology - protein “clocks”

Figure 13.3B

Human Rhesus monkey Mouse Chicken Frog Lamprey

Last commonancestor lived26 million yearsago (MYA),based onfossil evidence

80 MYA

275 MYA

330 MYA

450 MYA

Figure 15.8

No predestined goal of evolution

Varieties of life forms

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