Species as units: Taxonomy

1
(No Transcript)
2
Species as units Taxonomy
3
Species as units Phylogenetics
1
3
4
2
4
Species as units Biodiversity Studies
Conservation
Barthlott 1997
5
Geographic barriers to gene flow e.g., vicariance
6
Allopatric Speciation Deeper Evidence
Phylogeny of the 6 species of Geogenanthus
7
(No Transcript)
8
Non-Geographic barriers to gene flow e.g.,
polyploidy Anemone
1.) Mistake during cell division in meristem
(c-some duplication without mitosis or
cytokinesis). 2n to 4n. 2.) 4n plants can mate
with other 4n. Offspring are 4n and
fertile. 3.) 4n plants can mate with 2n
plants. But offspring are 3n. Irregular pairing
of homologous c-somes during meiosis. Offspring
sterile. 4.) 4n plants are isolated from 2n
plants.
9
Anthoxanthum odoratum
10
Evidence from empirical studies. Dodd (1989)
1.) dispersal across or emergence of a
barrier. 2.) change via drift or drift
selection. Over generations, change in enzyme
production. Mating selection to restrict
gene-flow. 3.) Remix, groups dont mix.
11
Allopatric Speciation Evidence from Cladograms
1
3
4
2
12

• 1900-1975
• Ukranian
• Emigrated to US in 1927.
• Columbia University.
• Drosophila genetics and systematics.
• Genetics and the Origins of Species (1937)
• Defined evolution as a change in the frequency
• Of an allele within a gene pool.
• Nothing in biology makes sense except in the
  light of evolution.

13
Speciation A cladogram perspective
1
3
4
2
14
Speciation A cladogram perspective
15
III. Species concepts A. Species as category vs.
Species as concept vs. species as entities
-Vast and somewhat confusing literature.
16
III. Species concepts A. Species as category vs.
Species as concept vs. species as entities
-Vast and somewhat confusing literature.
17
III. Species concepts A. Species as category vs.
Species as concept vs. species as entities
-Vast and somewhat confusing literature.
18
Platanus orientalis (Asia Minor to Iran)
Platanus occidentalis (N. America)
19
Platanus orientalis (Asia Minor to Iran)
Platanus occidentalis (N. America)
20
Ophrys spp. (Europe interfertile but isolated
via pollinators)
21
Ophrys spp. (Europe interfertile but isolated
via pollinators)
22
Ophrys spp. (Europe interfertile but isolated
via pollinators)
23
3) Phylogenetic Species Concept Hennig (1950
1966)
24
3) Phylogenetic Species Concepts contributors
to its practice
Cracraft (1983)
Nixon Wheeler (1990)
25
(No Transcript)
26
4) Ecological species concept Van Valen
(1976) Difficult species like Taraxacum
officinale more easily accommodated under this
concept.