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Unformatted text preview: oblems with the BSC
1.Often hard to assess interfertility
Can these interbreed?
endemic to Australia Eastern mole:
ranges over most of U.S. 40
40 Problems with the BSC
2. Can’t be applied to:
- asexually reproducing species
- extinct species
histolytica Same species? 41
41 Problems with the BSC 3. Viable Hybrids - Some species produce viable, robust hybrids.
Some hybrids can even be MORE robust Liger Beefalo 42
42 General pattern: most species are readily identifiable but
some species are less easily defined
Ernst Mayr: “Do we abandon the concept
of day and night because
they merge at dawn and dusk”? 47
47 Geographic variation within species
– subspecies or varieties
• occur in different areas
• are distinctive 48
48 2 Basic Patterns of speciation
1. Anagenesis Change within a lineage 2. Cladogenesis
Lineage splitting • Over time, one spp
transforms into another • Transformation of one
ancestral spp into
>1 descendant spp • Olde...
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