title: Evolution of exceptional species richness among lineages of fleshy-fruited Myrtaceae.
abstract: OBJECTIVE
  The angiosperm family Myrtaceae comprises 17 tribes with more than half of the estimated 5500 species being referred to the fleshy-fruited and predominantly rainforest associated Syzygieae and Myrteae. Previous studies suggest that fleshy fruits have evolved separately in these lineages, whereas generally shifts in fruit morphology have been variously implicated in diversification rate shifts among angiosperms. A phylogenetic hypothesis and estimate divergence times for Myrtaceae is developed as a basis to explore the evidence for, and drivers of, elevated diversification rates among the fleshy-fruited tribes of Myrtaceae.
  
  
  METHODS
  Bayesian phylogenetic analyses of plastid and nuclear DNA sequences were used to estimate intertribal relationships and lineage divergence times in Myrtaceae. Focusing on the fleshy-fruited tribes, a variety of statistical approaches were used to assess diversification rates and diversification rate shifts across the family.
  
  
  RESULTS
  Analyses of the sequence data provide a strongly supported phylogenetic hypothesis for Myrtaceae. Relative to previous studies, substantially younger ages for many of the clades are reported, and it is argued that the use of flexible calibrations to incorporate fossil data provides more realistic divergence estimates than the use of errorless point calibrations. It is found that Syzygieae and Myrteae have experienced elevated diversification rates relative to other lineages of Myrtaceae. Positive shifts in diversification rate have occurred separately in each lineage, associated with a shift from dry to fleshy fruit.
  
  
  CONCLUSIONS
  Fleshy fruits have evolved independently in Syzygieae and Myrteae, and this is accompanied by exceptional diversification rate shifts in both instances, suggesting that the evolution of fleshy fruits is a key innovation for rainforest Myrtaceae. Noting the scale dependency of this hypothesis, more complex explanations may be required to explain diversification rate shifts occurring within the fleshy-fruited tribes, and the suggested phylogenetic hypothesis provides an appropriate framework for this undertaking.
authors.affiliation: The Australian National University, Canberra, ACT 0200, Australia. Edward.biffin@adelaide.edu.au
authors.forename: Ed
authors.initials: E
authors.lastname: Biffin
authors.forename: Eve J
authors.initials: EJ
authors.lastname: Lucas
authors.forename: Lyn A
authors.initials: LA
authors.lastname: Craven
authors.forename: Itayguara
authors.initials: I
authors.lastname: Ribeiro da Costa
authors.forename: Mark G
authors.initials: MG
authors.lastname: Harrington
authors.forename: Michael D
authors.initials: MD
authors.lastname: Crisp
mesh_terms: D001499:Bayes Theorem; D019143:Evolution, Molecular; D005638:Fruit / Q000235:genetics; D027822:Myrtaceae / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics
references.citation: Evolution. 2001 Sep;55(9):1762-80
references.pmid: 11681732
references.citation: Am Nat. 2001 Jun;157(6):646-53
references.pmid: 18707281
references.citation: Proc Biol Sci. 2007 Dec 7;274(1628):2915-23
references.pmid: 17878143
references.citation: Trends Plant Sci. 2005 Nov;10(11):550-8
references.pmid: 16226053
references.citation: Mol Phylogenet Evol. 2005 Jun;35(3):569-82
references.pmid: 15878126
references.citation: Syst Biol. 2004 Oct;53(5):673-84
references.pmid: 15545248
references.citation: Biol Lett. 2007 Jun 22;3(3):275-9
references.pmid: 17363358
references.citation: Am J Bot. 2001 Nov;88(11):2013-25
references.pmid: 21669634
references.citation: Bioinformatics. 2008 Jan 1;24(1):129-31
references.pmid: 18006550
references.citation: Philos Trans R Soc Lond B Biol Sci. 2004 Oct 29;359(1450):1551-71
references.pmid: 15519972
references.citation: Syst Biol. 2007 Aug;56(4):591-608
references.pmid: 17654364
references.citation: Syst Biol. 2002 Dec;51(6):917-29
references.pmid: 12554458
references.citation: Bioinformatics. 2003 Aug 12;19(12):1572-4
references.pmid: 12912839
references.citation: Proc Biol Sci. 2005 Dec 7;272(1580):2535-44
references.pmid: 16271980
references.citation: PLoS Biol. 2006 May;4(5):e88
references.pmid: 16683862
references.citation: Evol Bioinform Online. 2007 Feb 14;2:273-6
references.pmid: 19455217
references.citation: Mol Biol Evol. 2006 Jan;23(1):212-26
references.pmid: 16177230
references.citation: Mol Phylogenet Evol. 2007 Apr;43(1):124-39
references.pmid: 17070713
references.citation: Mol Phylogenet Evol. 2007 Jul;44(1):399-411
references.pmid: 17433720
references.citation: BMC Evol Biol. 2007 Nov 08;7:214
references.pmid: 17996036
references.citation: Syst Biol. 2005 Aug;54(4):672-8
references.pmid: 16126662
references.citation: Proc Natl Acad Sci U S A. 2004 Feb 17;101(7):1904-9
references.pmid: 14766971
references.citation: Am Nat. 2006 Jun;167(6):808-25
references.pmid: 16685633
references.citation: Evolution. 1992 Feb;46(1):258-266
references.pmid: 28564968
references.citation: Proc Natl Acad Sci U S A. 1998 Aug 4;95(16):9402-6
references.pmid: 9689092
references.citation: Syst Biol. 2003 Oct;52(5):665-73
references.pmid: 14530133
references.citation: Mol Biol Evol. 2002 Jan;19(1):101-9
references.pmid: 11752195
references.citation: Am Nat. 2007 Aug;170 Suppl 2:S28-55
references.pmid: 17874383
references.citation: Science. 2001 Sep 21;293(5538):2242-5
references.pmid: 11567135
references.citation: Mol Biol Evol. 2004 Jan;21(1):188-99
references.pmid: 14595090