6-2/3 notes – biological evidence & plate tectonics chapter 6 lessons 2 & 3

6-2/3 Notes – 6-2/3 Notes – Biological EvidenceBiological Evidence

&&Plate TectonicsPlate Tectonics

Chapter 6

Lessons 2 & 3

Continental DriftContinental Drift• Acceptance of the continental drift

hypothesis led to the development of the theory of plate tectonics.

Continental DriftContinental Drift• As lithospheric plates move, they create

environmental changes for the organisms that live in or near them.

Continental DriftContinental Drift• The changes lead to the development of and

extinction of species.

Continental DriftContinental Drift• Australia has a large population of

mammals belonging to the group called marsupials. Few species of marsupials exist on other continents.

Geographic IsolationGeographic Isolation• Geographic isolation occurs when

populations of species are separated by a physical barrier.

Geographic IsolationGeographic Isolation• Once separated, the populations might

follow different evolutionary paths.

Geographic IsolationGeographic Isolation• The results of geographic isolation

prompted much of Darwin’s research.

Geographic IsolationGeographic Isolation• Species on an island were more similar to

those on the mainland even though the two environments were different.

Geographic IsolationGeographic Isolation• These observations led to the idea of

evolution by natural selection.

Geographic Isolation vs. Geographic Isolation vs. Convergent EvolutionConvergent Evolution

• Sometimes distant locations with similar environmental conditions have species with similar traits (analogous structures).

• The species developed independently but under similar conditions.


Octopuses and humans both have eyes - does that mean they share a recent

common ancestor?


No. Convergent evolution - when two separate groups of animals evolve to

have similar structures independently of one another.

wings of bats and birds prickly bits of porcupines and hedgehogs


• Convergent evolution results in structural and functional similarities.

• Examples include placental mammals in the Americas and marsupials in Australia.

What term describes the separation of populations by physical barriers?

A continental drift

B geographic isolation

C convergent evolution

D theory of plate tectonics

6.3 Evolution and Plate Tectonics

What did Darwin observe about geographically isolated populations?

A Species on distant islands with similar environmental conditions were similar.

B Species on islands and the mainland had undergone convergent evolution.

C Species on islands were similar to those on the mainland even though the environments were different.

D Species on the islands were more similar to each other than species on one island and the mainland.


What is the term for how very distantly related species can appear similar?

A geographic isolation

B recent common ancestry

C convergent evolution

D natural selection


What does NOT explain the gaps in the fossil record?

A Most organisms decay before fossilization.

B Fossils are unreliable for studying Earth’s history.

C Some fossils have not been found yet.

D Geological processes destroy fossils.

• Most organisms decay before fossilization.

• Some fossils have not been found yet.

• Geological processes destroy fossils.

These are the

reasons WHY.

Analogous structures are an indication of ____.

A convergent evolution

B a common ancestor

C continental drift

D geographic isolation

What does the fossil record NOT indicate?

A Species have evolved through natural selection.

B Most species that lived on Earth are extinct.

C Environmental conditions on Earth have not changed much.

D In Earth’s early history, life was less complex.

How does the movement of lithospheric plates possibly lead to the evolution of a new species?

A convergent evolution

B homologous structures

C environmental changes

D continental drift

SCI 4.f