Duva’s Reading Guide for POL Chapter 17: Speciation

Concept 17.1: Species Are Reproductively Isolated Lineages on the Tree of Life

I. Reproductive isolation:

II. Biological species concept:

III. Lineage species concept:

Concept 17.2: Speciation Is a Natural Consequence of Population Subdivision

I. Incompatibilities between genes can produce reproductive isolation.

The Dobzhansky-Muller model –

II. Reproductive isolation develops with increasing genetic divergence.

Concept 17.3: Speciation May Occur through Geographic Isolation or in Sympatry

I. Physical barriers give rise to allopatric speciation.

a. Allopatric speciation:

b. Ex. Darwin’s finches

II. Sympatric speciation occurs without physical barriers.

a. Sympatric speciation -

i. Disruptive selection

ii. Polyploidy

Concept 17.4: Reproductive Isolation Is Reinforced When Diverging Species Come into Contact

I. Prezygotic isolating mechanisms prevent hybridization between species.

a. Mechanical isolation

ex.

b. Temporal isolationex.

c. Behavioral isolationex.

d. Habitat isolationex.

e. Gametic isolationex.

II. Postzygotic isolating mechanisms result in selection against hybridization.

a. Reduced survival and reproductive rates of hybrid offspring

i. Low hybrid zygote viability

ii. Low hybrid adult viability

iii. Hybrid infertility

b. Hybrid zones

Duva’s Reading Guide for POL Chapter 18: The History of Life on Earth

Concept 18.1: Events in Earth’s History Can Be Dated

I. Principles of stratigraphy

a.

b.

c.

II. Radioisotopes provide a way to date rocks.

a. Half-life

b. Radiometric dating

c. Paleomagnetic dating

½¼

1/8 1/16

5.7 11.4 17.1 22.814C half-lives (thousands of years)

5,700

1.3 billion

4.5 billion

Nitrogen-14 (14N)

Argon-40 (40Ar)

Lead-206 (206Pb)

100 – 60,000

10 billion – 4.5 billion

10 billion – 4.5 billion

Concept 18.2: Changes in Earth’s Physical Environment Have Affected the Evolution of Life

I. The continents have not always been where they are today.

a. Plate tectonics

b. Continental drift

c. Mass extinctions

II. Earth’s climate has shifted between hot and cold conditions.

III. Volcanoes have occasionally changed the history of life.

IV. Extraterrestrial events have triggered changes on Earth.

V. Oxygen concentrations in Earth’s atmosphere have changed over time.

Firstlife

Firstaerobicbacteria

Firstphotosynthetic

bacteria

Firsteukaryotes

Firstmulticellulareukaryotes

Firstchordates

Invasionof land

Firstflowering

plants

Giant flying insects

Concept 18.3: Major Events in the Evolution of Life Can Be Read in the Fossil Record

I. Biota

a. Flora

b. Fauna

II. Precambrian life was small and aquatic.

III. Life expanded rapidly during the Cambrian period.

a. Cambrian explosion

b. Evolutionary radiations

IV. Many groups of organisms that arose during the Cambrian later diversified.

a. Punctuated equilibrium

b. Pangea

c. Mass extinctions