The Effects of Flower Color Transitions on Diversification Rates in Morning Glories (Ipomoea subg.Quamoclit,Convolvulaceae)

摘要：

　　As in many clades of flowering plants,the Quamoclit clade of morning glories (Ipomoea subgenusQuamoclit) exhibits unequal proportions of different flower colors,with pigmented species outnum-bering unpigmented species by nearly a factor of 7.We examined three possible macroevolutionaryexplanations for this pattern:(1) asymmetric transition rates between pigmented and unpigmentedflowers; (2) low transition rates preventing the flower colors from reaching equilibrium; and (3) dif-ferential diversification.In order to discriminate among these explanations,we employ the newly-developed Binary-State Speciation and Extinction (BiSSE) model,which jointly estimates transitionrates among states and the speciation and extinction rates in each state.Using maximum likelihoodand Bayesian BiSSE estimation,we find no evidence for asymmetrical transition rates.Also,BiSSEsimulations of character evolution demonstrate that there is sufficient time for the estimated transi-tion rates to produce as many or even more white species than we observe in Quamoclit,suggestingthat low-transition rates do not fully account for the paucity of white species.In contrast,we findsupport for the differential diversification hypothesis with the rate of speciation in pigmented line-ages estimated as three-fold greater than the rate in unpigmented lineages.Our analyses thus indicatethe low frequency of white-flowered morning glory species is due largely to lineage selection.Ouranalysis also suggests that estimating character transition rates without simultaneously estimatingspeciation and extinction rates can lead to greatly biased estimates of transition rates.

关键词： Anthocyanins diversification Ipomoea transition rate

作者: Stacey D.Smith Richard E.Miller Sarah P.Otto Richard G.FitzJohn Mark D.Rausher

作者单位: Department of Biology,Box 90338,Duke University,Durham,North Carolina,USA Department of Biological Sciences,Southeastern Louisiana University,Hammond,Louisiana 70402,USA Department of Zoology and Biodiversity Research Centre,University of British Columbia,Vancouver,Brit

会议类型: 国际会议

会议名称: The Darwin 200 Beijing International Conference (纪念达尔文诞辰200周年国际学术会议)

会议地点: 北京

会议语种:英文

页码: 202-226

在线出版日期: 2009-10-24（万方平台首次上网日期，不代表论文的发表时间）