Formation of species

CHAPTER 16 SECTION 3

The process of species formation is called?

Speciation

Scientists use internal and external structures and appearances ( morphology )as the criteria for classifying a species

This is the morphological species concept

Because morphological characteristics are easy to observe, makes species designations based on morphology becomes convenient

THE CONCEPT OF SPECIES

This concept states

A species is a population of organisms that can successfully interbreed but cannot breed with other groups

What happens if species reproduce asexually?

How do we define a species that is extinct then?

BIOLOGICAL SPECIES CONCEPT

We have to use both concepts!

They must be isolated from other species.

2 forms of isolation exist

Geographic Reproductive

HOW DO YOU MAKE A SPECIES?

The physical separation of members of a population

Can you think of species that are geographically isolated that may have similar species in other areas?

GEOGRAPHIC ISOLATION

Results from barriers to successfully breeding between population groups in the same areas.

This can occur in two ways; before fertilization and after

REPRODUCTIVE ISOLATION

Before fertilization occurs when fertilization cannot occur.

Mating calls not recognized by certain frogs, differences in mating periods

REPRODUCTIVE ISOLATION

After fertilization barriers occur usually with the offspring.

Mostly involve offspring that are sterile

REPRODUCTIVE ISOLATION

2 different rates

Gradualism Punctuated Equilibrium

RATES OF SPECIATION

Rapid Change

Slow, gradual change