Evolution II 1

Chapter 22: The Nature of Species

We will also cover some selected topics from

Chapters 23 -- intro to claudistics

Chapter 26-- Biological classification-- Domains vs kingdoms-- Intro to history of life

Evolution II 2

What is a species?

Scientific naming of species

Scientific binomial – Carolus Linnaeus

Genus + Species

Homo sapiens vs “humans”

Acer rubrum vs “red maple”

Writing Conventions

Definition

“A group of interbreeding organisms that are reproductively isolated”

What is ‘reproductive isolation’?

Biological classification system: Domain

Kingdom Phylum

Class Order

FamilyGenus Species

Which of these is Acer rubrum?

Question

Evolution II 3

What are some mechanisms of reproductive isolation?

Pre-zygotic

Ecological (habitat)e.g., mountain ranges

Mechanicale.g. reproductive anatomy

Temporale.g. mating seasons

Behaviorale.g., mating rituals

Gameticgametes incompatible(many plants)

e.g., frogs of Sierra Nevada foothillse.g., bowerbirds of Australia

Evolution II 4

Mechanisms of reproductive isolation, con’t.

Post-zygotic

Hybrid inviability-- embryo / fetus does not develop

e.g., cattle and water buffalo

Hybrid infertility-- offspring is infertile

e.g., colored and pied flycatchers

Meet and hybridize in central and northern EuropeQuestion

Evolution II 5

The biological species concept has limitations

If two species can hybridize, are they separate species?

-- plants-- animals

Should all dogs be classified in the same species?

Native: California Tiger Salamander Invasive: Adult Barred Tiger Salamander

Hybrid: Appears to bemore fit then native

http://sciencemode.com/2007/09/20/california-barred-tiger-salamanders-interbreed-produce-hybrids/

Evolution II 6

How does geographic distribution relate to speciation?

Allopatric speciation: geographic isolationmountains, rivers, islands

What evolutionary mechanisms can operate?

Can Sympatric speciation occur?

e.g., “blackbellied seedcracker”

Less fit hybrids -‘reinforcement’Reinforcement amongEuropean flycatchers

Question

Evolution II 7

Hawthorn

Apple

Apple Maggot

How can we explain the origin of the apple maggot?

Visit Martin G. Kelly’s site at http://www.sciencecases.org/maggot_fly/maggot_fly.asp

Evolution II 8

Under what conditions does ‘Adaptive Radiation’ occur?

-A special case of disruptive evolution

Darwin’s Finches -- classic example

Can occur regionally or globally-- rise of mammals

Adaptations reinforced by“Character Displacement’

Question

Evolution II 9

Plotting macroevolution

What are some characteristicsof evolution that can be diagrammed?

Gradualism vs ‘punctuated equilibrium’

Stephen J Gould & Niles Eldredge

What are possible mechanisms ofrapid speciation?

-- polyploidy-- mutations to developmental genes-- geologic time vs ‘human’ time

Evolution II 10

Plotting evolutionary relationships(from Chapter 23)

The traditional “evolutionary tree” vs Claudistics

Clade= all organisms with“Shared derived characteristics”

Evolution II 11

Revisiting Classification… (from Chapter 26)

Domains and Kingdoms

Biological classification system:Domain

KingdomPhylum

ClassOrder

FamilyGenus

Species

Question

Evolution II 12

Highlights of the History of Life(from Chapter 26)

Advanced life forms have appearedLate in earth’s geologic history

Origin of life ~ 3.8 bya

Eukaryotic cells ~ 1.7 bya

Multicellular organisms ~ 1.2 bya

Humans only ~ 1 mya

Origin of life

Multicellularorganisms

Evolution II 13

The origin of major groupsof animals

The ‘eras’

The Cambrian explosion

Vertebrates

Invertebrates

Age of reptiles

Age of mammals

Insects most successfulof them all

Evolution II 14

There have been many mass extinctions!

Some small,

Some BIG!

Question