1. Species concept

2. Mass Length Different species usually form clusters of phenotypes

4. ChronospeciesEvolutionary species

5. Species concepts What is a species? What are the criteria for defining a species?

6. Species consist of interbreeding populations that evolve independently of other populations

7. Species concepts Biological species concept Phylogenetic species concept Morphospecies concept

8. Species concepts Biological species concept - BSC species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups

9. Species concepts Biological species concept - BSC species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups Problems with BSC -asexual organisms -hybridization

10. Species concepts Phylogenetic species concept - PSC a species is a monophyletic group composed of the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent

12. Species concepts Phylogenetic species concept - PSC a species is a monophyletic group composed of the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent Problems with PSC -quantifying synapomorphies

13. Species concepts Morphospecies concept - MSC species are statistically distinguishable from others based upon an analysis of their morphological characteristics

14. Species concepts Morphospecies concept - MSC species are statistically distinguishable from others based upon an analysis of their morphological characteristics Problems with MSC -arbitrary -leads to cryptic species

15. Species concepts Biological species concept Phylogenetic species concept Morphospecies concept Beware the Procrustes fallacy!

16. Reliable criteria for identifying species are essential for preserving biodiversity

17. Indian elephantAfrican elephant

18. Indian elephantAfrican elephant African forest elephant

19. The speciation process begins when gene flow is disrupted and populations become genetically isolated

20. Prezygotic barriers 1 potential mates do not meet temporal isolation, habitat isolation 2 behavioral isolation 3 mechanical isolation 4 gametic incompatibility Barriers to gene flow

21. Prezygotic barriers 1 potential mates do not meet temporal isolation, habitat isolation 2 behavioral isolation 3 mechanical isolation 4 gametic incompatibility Postzygotic barriers 1 zygotic mortality 2 hybrid inviability 3 hybrid sterility 4 F 2 hybrid breakdown Barriers to gene flow

22. Hybridization occurs when offspring are produced by interbreeding between genetically different populations

23. In intermediate or transitional habitats, hybrid populations may be more fit than either parental population

24. Hybrid Zones Hybrid fitnessHybrid zoneOutcome < parentsnarrow, short livedreinforcement = parentswide, long livedcoalescence > parentsdependsstable zone or speciation