Species, Speciation & Hybridization - Lecture 9

Speciation is responsible for _____ evolution.

ALL

Natural selection, genetic drift, mutations & geneflow are the souces of micro_____

evolution

True Or False: There is 1 universal definition of a species

Nope

Taxonomic/ morphological species concept

Based on distinct phenotypic differences

Biological species concept

Based on inter-fertility among individuals

Biological species concept flaws

• focuses on the process of evolutionary reproductivity

• Not always easy to determine

• members of the same species must be possible interbreeding IN THE WILD (natural setting)

• does not apply well for asexuals, self fertilizing species, etc

Biological concept is the most _____ research method

common

Allopatric speciation process

• 2 evolving lineages that occur in different places (NO gene glow)

• Geographic isolation (barrier)

• divergence (no gene flow)

• new species in different places

Sympatric speciation process

• 2 lineages that are together

• experience a genetic change & reproductive isolation

• geneflow occurs locally

• New species within population (in the same place)

Steps to reproductive isolation

Pre zygotic isolation:

1. finding a mate 

2. successful fertilization

Post zygotic isolation:

1. development & growth of zygote

2. grows into adult & reproduces

3. Growth and survival of offspring

4 pre-zygotic reproductive isolation methods

1. geographical, ecological

2. Mate recognition

3. Genital structure

4. Sperm-egg compatibility

What causes post zygotic isolating barriers

Caused when hybrids are less fit because of their mixed genes

4 Types Of Microevolutionary processes

1. Natural Selection

2. Mutations

3. Gene Flow

4. Genetic Drift

True Or False: Allopatric occurs more commonly than Sympatric

True

2 types of Post-zygotic reproductive barriers

1. Intrinsic

2. Extrinsic

What Is Intrinsic Post Zygotic iIsolation

• Sterility of hybrids

When the hybrid or offspring can’t survive or reproduce
EX. mule & hinny (horse + donkey)

What Is Extrinsic Post Zygotic Isolation

Environmental mismatch of hybrid phenotype (because of natural selection)

Is adaptation required for speciation?

NO

Can adaptation help speed up speciation? if yes why?

Yes, quicker adpatation to environment = quicker speciation

Adaptive radiation

When one ancestral species quickly evolves into many new species, each adapted to a different environment or niche.

Adaptive radiation requirements (2)

• common ancestor 

• Various relationship between their phenotypes and environment

Causes of adaptive radiation

1. Ecological opportunity (resources are low)

• colonization

• extinction (of competitors) Vacancy for jobs

• key innovation (evolve a new trait)

2. Has to be able to evolve reproductive isolation very quickly

hybridization

Members of 2 different species that can produce offspring

• opposite of speciation

True Or False: hybridization can result in speciation

True

Polyploydi

Organisms with more than 2 homologuos chromosomes

Allopolypoydi

Fertile hybrid