Speciation 9/3

Define species

There are over 20 definitions of species, but only one is the best working definition. Biological species - organisms that are the same species if they freely interbreed and produce viable, fertile offspring.

Compare and contrast BSC to M/E/P-SC

MSC organisms that are the same species if they look alike
ESC organisms that are the same species if they share a habitat
PSC same species if you share a recent common ancestor

Biological SC are organisms that are the same species if they reproduce without human intervention and produce offspring that survives and is born, in which they can also produce their own offspring. Also relies on reproductive isolation.

What are the limitations of BSC?

1) Fossils uses morphological SC (you just look at them); cannot use BSC.
2) Reproduces asexually - thousands of bacteria do not reproduce sexually, but morphological and ecological.
3) Relies on absence of gene flow

List and describe pre-zygotic barriers of reproductive isolation

Organisms that do not mate freely at all. Pre = mating prevention. Egg + sperm does not equal zygote. (HGTMB)

1) habitat isolation - separated by BIG bodies of water, land, etc. or SMALL differentiation, such as apple vs. hawthorn maggot fly (different habitat)

2) temporal isolation - breeding season has to align, ex. pollen and flower

3) behavioral isolation - courtship rituals & mate recognition, birds have distinct courtship rituals, ex peacocks dancing - must speak each others love language - fireflies have different light patterns

4) mechanical isolation - reproductive parts have to fit

5) gametic isolation - gametes of different species can come together, but fail to fertilize and form a zygote (egg says no b/c not the right protein)

List and describe post-zygotic barriers of reproductive isolation

Think hybrids: reduced viability and reduced fertility (V,F).

1) A typical hybrid does not get through viability, but if born, they’re usually not healthy.

2) Different species pop champagne and produce a hybrid, but it is completely sterile and cannot produce its own offspring. Ex. horse x donkey = mule, but not mule x mule.

What is allopatric speciation? Give an example.

What is sympatric speciation? Give an example.

How do we get species?

Speciation

What are the two factors of reproductive isolation?

Pre-zygotic and post-zygotic

What does sterile mean?

Cannot produce offspring

What is ring species?

Ex. state of california where there are species of salamanders that interbreed with adjacent groups (and form hybrids), but two end habitats/populations overlap and cannot reproduce.