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

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

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

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

The Polyploid Complex Wow, this is complex!

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

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

The Polyploid Complex - Simplified 2n 2n 2n AA AA AA 4n 4n AAAA AAAA 6n AAAAAA

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

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

Lihova et al. 2003

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

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

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

Many intermediate characters Lihova et al. 2003

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

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?

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

Morphological Variation? Figure 5 Lihova et al. 2003

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

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

References Futuyma, D.J. 1998. Evolutionary Biology. Sinauer Associates – Sunderland, Mass. U.S. Grant, V. 1981. Plant Speciation. Columbia University Press, New York, pp. 324-346. Judd W.S., C.S. Cambell, E.A. Kellogg, P.F. Stevens, & M.J. Donoghue. 2002. Plant Systematics: An Evolutionary Approach. Sinauer Associates – Sunderland, Mass. U.S. Lee, J., K. Mummenhoff, & J. Brown. 2002. Allopolyploidization and evolution of species with reduced floral structures in Lepidium L. (Brassicaceae). PNAS 99(26): 16835-16840. Lihova, J., A. Tribsch, & K. Marhold. 2003. The Cardamine pratensis (Brassicaceae) group in the Iberian Peninsula: taxonomy, polyploidy and distribution. Taxon 52: 783-801. Marhold, K., & J. Lihova. 2006. Polyploidy, hybridization and reticulate evolution: lessons from the Brassicaceae. Pl. Syst. Evol. 259: 143-174.