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Background

With over 500 species worldwide, Diospyros is one of the largest angiosperm genera. Of the 11 main clades determined by Sutee Duangjai in 2009 (link), three occur in New Caledonia. Of the 31 New Caledonian species, all but one are endemic and one large group (24 species) shows evidence of rapid diversification following long-distance dispersal.

Current Work

Our group is applying molecular analysis of nuclear low copy genes, population genetic techniques (AFLP, RAD sequencing), and cytogenetics to explore evolutionary processes and interspecies interactions in the genus. These methods form the basis of Barbara Turner's doctoral work, here in Vienna.

The goal is to understand the complex processes of speciation among a diverse, but clearly defined species group in an island setting. Research themes include the extent of gene transfer between- and among paleoendemic and neoendemic lineages, the balance between ecological niche separation and genomic incompatibility in forming species boundaries, and molecular dating of the endemic clades.

New Caledonia

Located in the Pacific some 1300 km east of Australia and with a land area of about 19,000 km², this tropical archipelago is one of the world's 34 biodiversity hotspots. 75 % of the flora is endemic, but only small fragments of natural vegetation have survived human habitation.

The figures below are modified from Turner et al. 2013, Molecular Phylogenetics and Evolution. (Right-click to enlarge).

LEGEND:

Left figure: Bayesian maximum clade cred­ibil­ity tree from a com­bined nuclear & plastid DNA data set. Bold branches have >70 % sup­port from all three ana­lyses; blue dots indicate ≥70 % sup­port from at least one ana­lysis (Bayes­ian/maxi­mum parsi­mony/maxi­mum like­li­hood). New Cale­donian taxa are col­oured: red rep­re­sents the rapid­ly di­verg­ing clade III.

Figure in the middle: Chronogram from BEAST, based on a com­bined nuclear & plastid DNA data set. Ages are given (in million years) for nodes with >0.85 Bayesian post­erior prob­ab­ility. Black dots are cal­ibrated nodes. Yellow bars re­pre­sent the 95 % highest post­erior dens­ity inter­val. New Cale­donian taxa are col­oured: red rep­re­sents the rapid­ly di­verging clade III.

Right figure: One of 210 equal­ly pars­im­onious trees from plas­tid DNA sequences. Clades are named ac­cording to Duangjai et al., 2009. Bold branches have more than 70 % sup­port from all three ana­lyses. New Cale­donian taxa are col­oured: red rep­re­sents the rapidly di­verging clade III.

The figures below are modified from Turner et al. 2013, BMC Evolutionary Biology.  (Right-click to enlarge).

Genome size

Rapid speciation might have been accompanied by large-scale changes in genome structure.

Polyploidy is rare in Diospyros, and all of the species examined from New Caledonia have been diploid, with 2n = 30 chromosomes.

Despite this we see large variation in genome size, from 0.86 pg in D. olen to 2.3 pg in D. pancheri. Members of Sutee Duangjai's clade III tend to have far larger genomes; this is also the clade that exhibits the greatest diversity and most rapid diversification among New Caledonian species.

The figures below have been published in Sutee's 2006 and 2009 papers. (Right-click to enlarge).

LEGEND:

Left figure: Figure 4 in Duang­jai et al., 2006.
Bayesian majority-rule prob­abil­ity tree from ana­lysis of the com­bined plas­tid reg­ions. Post­erior prob­abil­ities are given above bran­ches. Pres­ence of ovary type and number of floral parts, which have been impor­tant char­acters used in Eben­aceae taxon­omy in the past, are ind­ic­ated with symbols to right of the tree. Ovary pos­ition can be either sup­erior (black bar) or inf­erior (white bar). Num­ber of floral parts can be div­ided into four classes: tri­merous flowers (▵), tetra­merous flowers (█), penta­merous flowers (*), and hexa­merous flowers (○).

Right figure: Figure 4 in Duang­jai et al., 2009.
Bio­geo­graph­ical opt­im­iz­ation based on dis­pers­al-vic­ar­iance ana­lyses per­form­ed with the pro­gram DIVA (Ron­quist, 1996) using one of the 15,000 equal­ly-most pars­im­onious trees res­ult­ing from MP ana­lysis of Eben­aceae. Taxa in red are spec­ies from New Cale­donia. The dis­trib­ution of each taxon and the clade num­ber are ind­ic­ated to the right of the tree. Color leg­end: Afr­ica and Madag­ascar; India and Sri Lan­ka; Aus­tral­ia; New Cale­donia; Pac­ific Is­lands; Eur­asia; South Am­er­ica; Cent­ral and North Am­er­ica.

1. Nakutakoin
2. Dumbea
3. Between Plum and Prony
4. Col de Prony
5. Forêt du Grand Kaori
6. Port-Boisé
7. Kuébini
8. La Roche Percée
9. Pindai/Népoui
10. Voh
11. Between Koné and Poindimié
12. Conservátoire botanique de Tiéa
13. Aoupinié
14. Nétéa
15. Mandjelia
16. Koumac
17. Koumac
18. Paagouméne
19. Baie de Gadji
20. Yahoué
21. Forêt de la Superbe (Montagne des Sources)
22. Moindah
23. Plateau de Tiéa
24. Plateau de Tango
25. Népou
26. Ile Kuébini
27. Ile des Pins
28. Ile des Pins, Pic N'ga
29. Thio, Tô De

Papers

Turner B, Paun O, Munzinger J, Chase MW, Samuel R. 2016. Sequencing of whole plastid genomes and nuclear ribosomal DNA of Diospyros species (Ebenaceae) endemic to New Caledonia: many species, little divergence. Annals of Botany 117: 1175-85.

Paun O, Turner B, Trucchi E, Munzinger J, Chase MW, Samuel R. 2016. Processes Driving the Adaptive Radiation of a Tropical Tree (Diospyros, Ebenaceae) in New Caledonia, a Biodiversity Hotspot. Systematic Biology 65: 212-27.

Turner B, Paun O, Munzinger J, Duangjai S, Chase MW, Samuel R. 2013. Analyses of amplified fragment length polymorphisms (AFLP) indicate rapid radiation of Diospyros species (Ebenaceae) endemic to New Caledonia. BMC Evolutionary Biology 13: 269.

Turner B, Munzinger J, Duangjai S, Temsch EM, Stockenhuber R, Barfuss MHJ, Chase MW, Samuel R. 2013. Molecular phylogenetics of New Caledonian Diospyros (Ebenaceae) using plastid and nuclear markers. Molecular Phylogenetics and Evolution 69: 740–763.

Duangjai S, Samuel R, Munzinger J, Forest F, Wallnöfer B, Barfuss MHJ, Fischer G, & Chase MW. 2009. A multi-locus plastid phylogenetic analysis of the pantropical genus Diospyros (Ebenaceae), with an emphasis on the radiation and biogeographic origins of the New Caledonian endemic species. Molecular Phylogenetics and Evolution 52: 602–620.

Duangjai S, Wallnöfer B, Samuel R, Munzinger J, & Chase MW. 2006. Generic delimitation and relationships in Ebenaceae sensu lato: evidence from six plastid DNA regions. American Journal of Botany 93: 1808–1827.

Conference presentations

Turner B, Paun O, Munzinger J, Duangjai S, Chase MW, Samuel R. 2013. Evolution of New Caledonian Diospyros species (Ebenaceae). Plant Genome Evolution 2013 in Amsterdam, The Netherlands, 8–10 September 2013. [Poster]

Turner B, Munzinger J, Duangjai S, Barfuss MHJ, Wallnöfer B, Paun O, Chase MW, Samuel R. 2012. Diversification of endemic New Caledonian Diospyros (Ebenaceae). 15. Treffen der Österreichischen Botanikerinnen und Botaniker in Innsbruck, Austria, 27–29 September 2012. Berichte des naturwissenschaftlich-medizinischen Vereins in Innsbruck, Supplementum 20.

Turner B, Munzinger J, Duangjai S, Temsch E, Wallnöfer B, Chase MW, Samuel R. 2012. Speciation of New Caledonian Diospyros (Ebenaceae). International Conference on Polyploidy, Hybridization and Biodiversity in Průhonice, Czech Republic, 7–10 May 2012. [Poster]

Samuel R, Turner B, Duangjai S, Munzinger J, Wallnöfer B, Chase MW. 2011. Pattern and mode of speciation of New Caledonian Diospyros (Ebenaceae). IBC2011: XVIII International Botanical Congress in Melbourne, Australia, 23–30 July 2011.

Samuel R, Turner B, Duangjai S, Munzinger J, Wallnöfer B, Chase MW, Barfuss MHJ. 2011. Origin and evolution of New Caledonian Diospyros (Ebenaceae): a phylogenetic approach. IBC2011: XVIII International Botanical Congress in Melbourne, Australia, 23–30 July 2011. [Poster]

Duangjai S, Samuel R, Munzinger J, Wallnöfer B, Forest F, Barfuss MHJ, Chase MW. 2010. Biogeographic origins and evolution of endemic species of Diospyros (Ebenaceae) from New Caledonia: A molecular phylogenetic perspective. 19th International Symposium “Biodiversity and Evolutionary Biology” of the German Botanical Society (DBG) in Vienna, Austria, 16–19 September 2010.

Duangjai S, Samuel R, Wallnoefer B, Munzinger J, Yakandawela D, Chase MW. 2008. A phylogenetic framework for infrageneric classification of Diospyros (Ebenaceae) with an emphasis on a radiation of species in New Caledonia. Botany 2008: Botany without Borders in Vancouver, Canada, 26–30 July 2008.

Duangjai S, Wallnöfer B, Samuel R, Munzinger J, Chase MW. 2006. Phylogenetic relationships and infrafamilial classification of Ebenaceae s.l. based on six plastid markers. Botany 2006: Looking to the future—Conserving the past in Chico, California, USA, 29 July–2 August 2006.

Duangjai S, Samuel R, Wallnöfer B, Chase MW. 2005. Phylogenetic relationships of Ebenaceae: inferred from four regions of plastid DNA and ncp glutamine synthetase. XVII International Botanical Congress in Vienna, Austria, 17–23 July 2005.