Darwin wrote up his observations and conclusions (including evidence) in a book, but waited 10 years to publish it

________________ independently arrived at the same conclusions and sent him an essay to read Known as the father of biogeography

Darwin published ____________________the next year, on ___________________________

________________ : an individual’s adaptation to the environment as measured by its relative genetic contribution to future generations

Descent with modification happens when:

___________________________________________

_______________________________________

500 years ago, Leonardo da Vinci questioned the existence of __________________________________

Prevailing belief: deposited by an ancient flood Rocks composed of cake-like layers; some

contained shells while others did not Considered it to be similar to spring flooding of

rivers and the deposition of silt on riverbeds If layers had been deposited over time, vertical

sequence of fossils would be a fossil record of past life

By the 1700s, fossils were accepted as remains or impressions of organisms that lived in the past

Fossil: from translation of Latin word

meaning __________________________ Interpretation of fossils often

influenced by cultural beliefs

Most fossils are remains of __________________ ________________________________________

Trace fossils are indirect evidence obtained from impressions Example: tracks

___________ are fossilized feces

Why are fossils hard parts instead of soft matter?

The ________________ process is very slow Begins when an organism dies and is

covered in ash or sediment Water infiltrates the remains, and metal

ions or other inorganic molecules replace the organic ones in bones or other hard tissues

Soft tissues often decay The pressure increases from additional

sediment deposited on top.

Pressure + mineralization = transformation of the remains into stony fossils

Fossilization is favored when remains are ___________________ and remain ____________ These conditions are rare; therefore,

fossils are rare Also must remain undisturbed

Scavengers and erosion often make this difficult…

Sediment particles (including silt, sand, volcanic ash, and other particles) settle and become compressed

Over time, the layers of sedimentary rock form in varying thickness

___________________ : the formation of layered sedimentary rock

The layers and their chemical/physical properties provide context for the fossils found within them

Figure 16.10, page 247

Currently more than 250,000 species of fossils Fossil record will ___________ be complete Unlikely that a fossil of each species that has

ever lived will be found Favors species with hard parts, dense

populations with wide distribution, and that persisted a long time

________________ (line of descent) of organisms that were remote or lived for brief periods of geologic time are less likely to be represented

Fossil dating became more accurate with the discovery of radioisotope decay

________________ : a form of an element with an unstable nucleus that decays and becomes other elements

Decay not influenced by environmental factors; serves as a predictable and constant clock

Used to date fossils and rocks More recent fossils may be dated using their

ratio of carbon isotopes (carbon dating)

Early geologists counted backward through layers of sedimentary rock to observe transitions in the fossil sequence around the world

Similar transitions were observed in different locations around the world

These became the basis for divisions in

the ___________________________

A chronology of the Earth’s history Boundaries for major intervals can be

determined by transitions in the fossil record Major divisions can be correlated with

macroevolutionary events Includes dates obtained by radiometric

dating

_____________________ : major patterns, trends, and rates of change among lineages

Geologic time clock

Figure 16.13, page 249

Figure 16.12, page 249

Model suggests that all continents were part of a large supercontinent called _______________ Eventually split and drifted apart Gondwana: southern supercontinent

Jigsaw-like fit between the Atlantic Ocean coastlines of South America and Africa

Helped explain why the same fossils appear in sedimentary rocks on both sides of the ocean

This theory is called plate tectonics

Movements of Earth’s tectonic plates on outer layer of rock rafted land masses to new positions

Movements had profound impacts on the directions of life’s evolution

Evidence for plate tectonics theory Distribution of global land masses Global fossil distribution Magnetic rocks found in different places around the

world Seafloor spreading from mid-oceanic ridges (fissures)

Figure 16.13, page 249

d 66 myac 152 myab 237 myaa 420 mya e 14 mya

We now know that continents collide, split, and move vast distances over the surface of the Earth.

Continental drift (plate tectonics) influences life and evolutionary forces on land and in the oceans

________________ _______________ is the study of body forms and structures of major groups of organisms, such as vertebrates and plants

Similarities between species may indicate evidence of descent from a common ancestor

_____________ _____________ : similar body parts shared among related organisms The structures may be used differently, but

the same genes direct their development

In time, isolated populations begin diverging genetically

Over time, differences appear in body form

This macroevolutionary process is called ________________________________

In spite of changes in form, a careful examination reveals common heritage

Example: the four-legged ancestry of land vertebrates

Divergences led to the major vertebrate groups Divergence seen in the five-toed limb

The same five-toed limb has been modified into a human arm, an elephant foot, or bird wing

Although they differ in use, size, and shape, they retain the same structure and positioning of bony elements

Figure 16.16, page 252

• Certain bones were lost over time• Example: digits

numbered 1-5• Bones of

forearms: colored in orange and pink

Stem reptile (a cotylosaur)

4

3

21

pterosaur

Figure 16.16, page 252

3

2

1

chicken

Figure 16.16, page 252

3

2

penguin

Figure 16.16, page 252

Figure 16.16, page 252

543

2

1

porpoise

Figure 16.16, page 252

543

2

1

bat

Figure 16.16, page 252

54

3 2

1

human

Figure 16.16, page 252

5

4

3

21

elephant

Similar body parts are NOT always homologous and do not always share a common lineage

They may have evolved independently in separate lineages

_______________________ look alike in different

lineages but did not evolve in a shared

ancestor

____________________________: evolution of

similar body parts in different lineages

Example: ______________________________ All act in flight but examination of

their structure reveals that they are not homologous

Unique adaptation for flight are evidence that wing surfaces in bats, birds, and insects are analogous

Figure 16.17, page 253