1. Two Species or Not Two Species?
What do you think?

2. Definition of Species
A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g., Homo sapiens .

3. Horses and Donkeys

4. Lions and Tigers

5. Wolves and Dogs

6. Dogs
Chihuahua
Great Dane

7. Forest frog and Leopard frog

8. Horses and Donkeys
Mule - infertile

9. Lions and Tigers
Liger - infertile

10. Wolves and Dogs
Wolf-dog: Fertile (most cases). Domesticated dog is a subspecies of Grey Wolf. There are distinct DNA differences. Can be issues with hybrid. So they can reproduce successfully (fertile offspring), but are some issues, so called a subspecies of Grey Wolf, not other wolves species.

11. Dogs
Chihuahua
Offspring - Fertile
Great Dane

12. Forest frog and Leopard frog
Offspring – Fertile, but…..
New species of Leopard Frog discovered in NYC that can’t mate with either…new species, no name yet

13. Can’t reproduce for many reasons…..
Genetically, some animals could reproduce, but they can’t for some specific reasons…..due to “isolation”
Why can’t they?

14. Can’t reproduce for many reasons…..
Genetically, some animals could reproduce, but they can’t for some specific reasons…..due to “isolation”
Or, they could at one time, became “isolated” and not can no longer reproduce (too many differences and such)
Why can’t they?

15. Can’t reproduce for many reasons…..
Populations separated physically by geographic barriers that prevent breeding
Populations separated by different times in breeding season that prevent breeding
Populations separated by courtship or other differences that prevent breeding
Geographic Isolation
Temporal Isolation
Behavioral Isolation