Phylogeographic Inference of a Hybridizing Complex: Ipomoea section Batatas George P. Tiley Southeastern Louisiana University Hammond, La I. sect. Batatas

Investigating evolution of hybridizing complexes is important Informs how we think about species concepts Hybridization can arise from a breakdown of pre-zygotic or post-zygotic barriers Potentially informative about geographic history Ecological implications

Why study Ipomoea section Batatas? The tribe Ipomoeeae constitutes approximately 900 specie Generally do not hybridize Distinct species boundaries Ipomoea section Batatas constitutes 14 named species Exhibits degrees of hybridization between species Sympatric and allopatric distributions Includes sweet potato, I. batatas

(MANOS and MILLER, 2001) I. section Batatas I. section Batatas is a new world clade

Support for speciation by hybridiztion through polyploidy species2ncountry of origin I. leucantha2n = 2x = 30Mexico, Tabasco I. tiliacea2n = 2x = 30Mexico, Tabasco I. triloba2n = 2x = 30Mexico I. trifida 2A2n = 2x = 30Colombia I. trifida 2B2n = 2x = 30Colombia I. setosa2n = 2x = 30U.S. I. tabascana2n = 4x = 60Mexico I. trifida (4A)2n = 4x = 60Collection from CIP I. trifida (4B)2n = 4x = 60Collection from CIP I. trifida (4C)2n = 4x = 60Collection from CIP I. trifida (4D)2n = 4x = 60Collection from CIP I. trifida (4E)2n = 4x = 60Collection from CIP I. batatas (Ib1)2n = 6x = 90Philippines I. batatas (Ib2.1)2n = 6x = 90Peru I. batatas (Ib2.2)2n = 6x = 90Peru I. batatas (Ib3)2n = 6x = 90Indonesia I. batatas (Ib4)2n = 6x = 90Puerto Rico I. batatas (Ib5.1)2n = 6x = 90U.S I. batatas (Ib5.2)2n = 6x = 90U.S. I. batatas (Ib6)2n = 6x = 90South Korea I. batatas (Ib7)2n = 6x = 90China I. batatas (Z13)2n = 6x = 90China diploid and tetraploid varieties of the same named species (Srisuwan et al, 2006)

Sympatric and allopatric distributions of some species speciesupper boundlower bound I. batatascentral Mexico and Carribean IslandsParaguay and E Brazil I. tiliaceaSE Mexicoand Carribean IslandsW Venezuela and E Brazil I. lacunosaCentral U.S.SE U.S. I. cordatotrilobaSE U.S.NE Mexico I. tenuissimaCoastal FloridaCarriben Islands I. trilobaCoastal Mexico and Carribean IslandsBelize and West Indies I. trifidaMexico and CubaN South America and E Brazil I.ramosissimaW Mexico and Central AmericaN Argentina and SE Brazil I. littoralisSE Mexico and Australia- Interpolated from D.F. Austin (1978) U.S. distributions Widespread Indo-Pacific

Crossing Study supports hybridization between species batcorcyngralacramtentiltrftrlleufemale bat-xx0.00x xx0.09xx corx-x/0.32x/0.57xx/0.20xxx/0.01x0.27/0.38 cyn0.00x-0.67xxxxx0.83x gra0.00x0.55-xxxxxxx lacx0.45xx-xxxxxx ram0.00xx0.18x-xx x/0.00 tenxxxxx0.57-x0.07xx til0.00xxxxxx-xxx trf / x0.20xx trl0.00x/0.40x0.18xxxxx-0.95/0.25 leu x0.52xx /0.06- male x indicates no cross was performed data from Diaz et al. (1996)

Phylogenetic hypotheses data from Rajapaske et al. (2004)

Phylogeographic Analysis: data Primers designed PCR amplification 54 of 65 taxa diploid (presented today) Polyploids cloned Direct sequencing of PCR product DFRBUF3GTANStrnD-trnT aligned length invariable gaps variable singletons parsimony informative

Phylogeographic Analysis: Phylogenetic reconstruction Mr Bayes MPI format Partition by intron, exon, codon position GTR + Γ model of nucleotide substitution Inferred by AIC and BIC Ran until chains converged 5,000,000 generations 1,250,000 burn-in +/- 3% posterior probabilities across nodes Split average standard deviation:

% Majority Rule Consensus Tree

Phylogeographic Analysis: Interpreting Phylogeny Treat as a single population Assume admixture Structure Infer number of subpopulations in I. section Batatas

What claims can we make about the dynamics of a hybridizing complex? Mixture of species and population level patterns Ancestor-descendent lineages Panmictic units of named species A strict phylogenetic approach is not appropriate Dense taxon sampling greatly alters topology Assumptions of an evolutionary process will impose a topology on species, despite the true history

Species concepts have tremendous impact on the taxonomy of hybridizing complexes We only adopt these species names under a morphological species concept These species do have morphological distinctions We lack the monophyletic groups to support previous hypotheses I. umbraticolaI. lacunosa

Future Directions More data Done Investigate the origin of polyploidy Done Utilize population genetic inference adopted under a phylogenetic framework Perform statistical hypothesis testing for historical or extemporaneous geographic hypotheses Finish collecting vouchers for all specimens Check IDs for all specimens

Thank you USDA-ARS Bob Jarret The Miller Lab Lauren Eserman Saroj Simkhada Daniel F. Austin Alyssa Brown I. cordatotriloba