1. Polyploidy: Tricky Taxonomic Delimitation
Ben Grady
UW-Madison
Botany Department
6 March 2007

2. Polyploidy and Taxonomy: an overview
“Defining” species
Polyploid complexes
Cardamine pratenesis
Lepidium

3. What do we call a species?
Biological Species Concept
Mayr 1942
Evolutionary Species Concept
Wiley 1978
Phylogenetic Species Concept
Cracraft 1989
General consensus: diagnosable units with common evolutionary history
From Futuyma 1998 and Judd et al. 2002

4. The Polyploid Complex Continued polyploidization in a group or lineage
Much overlap in morphological traits and ecological preferences
Difficult and time-consuming to fully understand relationships within a polyploid complex
Grant 1981

5. The Polyploid Complex
Wow, this is complex!

6. The Polyploid Complex Count some chromosomes 2n 2n 2n 2n 2n 4n 4n 2n

7. The Polyploid Complex Determine source of genetic material 2n 2n 2n 2n

8. The Polyploid Complex - Simplified2n 2n 2n AA AA AA 4n 4n
AAAA
AAAA 6n
AAAAAA

9. The prevalence of Polyploid Complexes
Polyploid complexes are common in certain families
Polypodiaceae
Trilliaceae
Onagraceae
Poaceae
Brassicaceae
Grant 1981

10. Cardamine pratensis complex
Widespread distribution
Morphological variation not discrete
Post-glacial diversification
Hybridization and polyploidy rampant
2n = 16, 24, 30, 32, 40, 44, 46, 48, 56
Iberian taxa:
C. pratensis s.s.
C. crassifolia
C. castellana
Photos © Carl Farmer
Lihova et al. 2003

11. Lihova et al. 2003

12. C. pratensis
C. pratensis
C. castellana
C. crassifolia
Lihova et al. 2003

13. C. pratensis in the Iberian Peninsula Lihova et al. 2003
C. crassifolia and C. castellana appear distinct (both taxa 2n=16)
C. castellana C. crassifolia

14. AFLP analysis: C. castellana & C. crassifolia
C. castellana 2n = 16
C. crassifolia 2n = 16
Lihova et al. 2003

15. Many intermediate characters
Lihova et al. 2003

16. Origins of C. castellana?
C. castellana morphologically intermediate
Possible hybrid of C. pratensis and C. crassifolia
What then?
Species?
Subspecies?
No taxonomic recognition?

17. C. pratensis in the Iberian Peninsula Lihova et al. 2003
C. pratensis s.s. still poses a problem, or does it?
Various polyploids still mostly interfertile (except diploids)
Morphological variation continuous
Multiple origins of polyploids?

18. AFLP analysis: C. pratensis s.s.30 16 56 56 44
Lihova et al. 2003

19. Morphological Variation?
Figure 5
Lihova et al. 2003

20. Allopolyploidization – Lepidium Lee et al. 2002
175 spp. worldwide
Crazy flowers, well for a mustard…

21. PI gene tree and evolution of stamen arrangement, green-Eurasia, orange-Africa, blue-S.Amer., black-Austr., purple-N.Amer. lacking lateral stamens,

22. References
Futuyma, D.J Evolutionary Biology. Sinauer Associates – Sunderland, Mass. U.S.
Grant, V Plant Speciation. Columbia University Press, New York, pp
Judd W.S., C.S. Cambell, E.A. Kellogg, P.F. Stevens, & M.J. Donoghue Plant Systematics: An Evolutionary Approach. Sinauer Associates – Sunderland, Mass. U.S.
Lee, J., K. Mummenhoff, & J. Brown Allopolyploidization and evolution of species with reduced floral structures in Lepidium L. (Brassicaceae). PNAS 99(26):
Lihova, J., A. Tribsch, & K. Marhold The Cardamine pratensis (Brassicaceae) group in the Iberian Peninsula: taxonomy, polyploidy and distribution. Taxon 52:
Marhold, K., & J. Lihova Polyploidy, hybridization and reticulate evolution: lessons from the Brassicaceae. Pl. Syst. Evol. 259: