EVOLUTIONARY HISTORY OF THE MATING SYSTEM INAMSINCKIA(BORAGINACEAE)

Abstract

A survey of restriction site variation in the chloroplast genome of the annual plant genus Amsinckia, together with estimation of outcrossing rates, was conducted to analyze the evolutionary history of the mating system. Species, and in some cases populations within species, differ markedly in their mating system. Five taxa are distylous and predominantly outcrossing, or show mixed mating systems, while the remaining taxa are homostylous and predominantly self-fertilizing. Reconstruction of the molecular phylogeny of the group places different distylous and homostylous taxa at four separate branch tips. When distyly is treated as ancestral in the group, or when the loss of distyly is assumed to be more common than its gain, the results of the phylogenetic analysis support the hypothesis that the self-fertilizing taxa are of recent origin from outcrossing relatives. These findings are discussed with respect to theory for the evolution and breakdown of distyly and the probability of extinction of selfing lineages.

Phylogenetic relationships, chromosome and breeding system evolution inTurnera(Turneraceae): inferences from its sequence data

“…Associations between homostyly and polyploidy occur in some lineages of Amsinckia (Schoen et al, 1997), Primula (Conti et al, 2000), Damnacanthus (Rubiaceae; Naiki and Nagamasu, 2004), and Turnera, supporting the derived nature of homostyly in those cases. For the present data set, we have assumed distyly to be ancestral in Turnera.…”

“…In particular, an increasing number of families possessing heterostylous species are beginning to be investigated (e.g., Kohn et al, 1996;Schoen et al, 1997;Graham et al, 1998;Conti et al, 2000;Mast et al, 2001;Church, 2003;Peréz et al, 2003;Graham and Barrett, 2004). Schoen et al (1997) explored various mappings of breeding system evolution onto a molecular phylogeny and detailed arguments supporting the proposition that distyly is ancestral in Amsinckia. Similar arguments were made for the evolution of breeding systems in the Pontederiaceae (Kohn et al, 1996).…”

“…Phylogenetic analysis is necessary for hypotheses on the evolutionary pathways of distylous groups to be tested (Donoghue, 1989;Weller and Sakai, 1999). Phylogenetic analyses and character mapping in the Pontederiaceae (Kohn et al, 1996;Graham et al, 1998;Huelsenbeck et al, 2003), Amsinckia (Schoen et al, 1997), Primula (Conti et al, 2000), and Narcissus (Graham and Barrett, 2004) have explored hypotheses for breeding system evolution within these heterostylous taxa. Molecular data readily lends itself to phylogenetic studies of heterostyly as the characters used to examine relationships are likely to be independent of the morphological trait changes associated with breeding system evolution (Barrett, 1992).…”

Multiple Origins of Self-Compatibility in Linanthus Section leptosiphon (Polemoniaceae): Phylogenetic Evidence from Internal-Transcribed-Spacer Sequence Data

“…Recent phylogenetic studies show that selling has arisen multiple times within a single genus or family (Kohn et al 1996;Schoen et al 1997). Indeed, variation in mating systems is present among populations of many plant species (Lloyd 1965;Moore and Lewis 1965;Schoen 1982;Wyatt 1986;Holtsford and Ellstrand 1990;Johnston and Schoen 1996), and selling variants have been shown to have multiple independent origins at that taxonomic scale (Lloyd 1965;Wyatt 1988;Husband and Barrett 1 1993).…”

The Interaction between Selection, Demography and Selfing and How It Affects Population Viability

“…Despite this transition rate, and high speciation rates in selfers compared to outcrossers, outcrossers still represent more than 40% of species in this family. Other studies in other plant families also come to this conclusion [30]–[32]. Goldberg et al [29] show that this puzzling prevalence of outcrossers is due to higher extinction rates in selfing species than in outcrossing ones.…”