Founder effects and sex ratio in the gynodioecious <i>Thymus vulgaris</i> L.

Manicacci, Doménica; Couvet, Denis; Belhassen, E.; Gouyon, Pierre‐Henri; Atlan, Anne

doi:10.1111/j.1365-294x.1996.tb00291.x

Cited by 66 publications

(67 citation statements)

References 40 publications

(16 reference statements)

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“…Gynodioecy determined by the nuclear-cytoplasmic inheritance often has a large variation in sex ratio among populations (Manicacci et al 1996;Delph & Carroll 2001), whereas gynodioecious populations determined by nuclear inheritance have a stable sex ratio and the frequency of female plants might not exceed 50% (Bailey & Delph 2007;Spigler & Ashman 2012). Small variation in sex ratio among populations and over years suggests that gynodioecy in D. jezoensis is determined by the nuclear inheritance system.…”

Section: Sex Ratio and Sexual Labilitymentioning

confidence: 96%

Male‐biased hermaphrodites in a gynodioecious shrub,Daphne jezoensis

et al. 2016

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Gynodioecy, a state where female and hermaphrodite plants coexist in populations, has been widely proposed an intermediate stage in the evolutionary pathway from hermaphroditism to dioecy. In the gynodioecy-dioecy pathway, hermaphrodites may gain most of their fitness through male function once females invade populations. To test this prediction, comprehensive studies on sex ratio variation across populations and reproductive characteristics of hermaphrodite and female phenotypes are necessary. This study examined the variation in sex ratio, sex expression, flower and fruit production and sexual dimorphism of morphological traits in a gynodioecious shrub, Daphne jezoensis, over multiple populations and years. Population sex ratio (hermaphrodite:female) was close to 1:1 or slightly hermaphrodite-biased. Sex type of individual plants was largely fixed, but 15% of plants changed their sex during a 6-year census. Hermaphrodite plants produced larger flowers and invested 2.5 times more resources in flower production than female plants, but they exhibited remarkably low fruit set (proportion of flowers setting fruits). Female plants produced six times more fruits than hermaphrodite plants. Low fruiting ability of hermaphrodite plants was retained even when hand-pollination was performed. Fruit production of female plants was restricted by pollen limitation under natural conditions, irrespective of high potential fecundity, and this minimised the difference in resources allocated to reproduction between the sexes. Negative effects of previous flower and fruit production on current reproduction were not apparent in both sexes. This study suggests that gynodioecy in this species is functionally close to a dioecious mating system: smaller flower production with larger fruiting ability in female plants, and larger flower production with little fruiting ability in hermaphrodite plants.

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Section: Sex Ratio and Sexual Labilitymentioning

confidence: 96%

Male‐biased hermaphrodites in a gynodioecious shrub,Daphne jezoensis

et al. 2016

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“…Indeed, about 50% of trees from Brownhill Creek display haplotype 9 (referred as CCK in Besnard et al, 2000), which was shown to be strictly associated to a cytoplasmic male sterility (CMS) in cultivars (Besnard et al, 2000). This CMS may play a significant role in the dynamics of invasion since male sterile individuals are known to be very vigorous in olives (for example, cultivars Zarazi, Chemlal or Olivière; Besnard et al, 2000) and should therefore be favored in the initial establishment of populations compared to hermaphrodites as shown in Thymus vulgaris (Manicacci et al, 1996).…”

Section: Discussionmentioning

confidence: 99%

On the origin of the invasive olives (Olea europaea L., Oleaceae)

et al. 2007

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The olive tree (Olea europaea) has successfully invaded several regions in Australia and Pacific islands. Two olive subspecies (subspp. europaea and cuspidata) were first introduced in these areas during the nineteenth century. In the present study, we determine the origin of invasive olives and investigate the importance of historical effects on the genetic diversity of populations. Four invasive populations from Australia and Hawaii were characterized using eight nuclear DNA microsatellites, plastid DNA markers as well as ITS-1 sequences. Based on these data, their genetic similarity with native populations was investigated, and it was determined that East Australian and Hawaiian populations (subsp. cuspidata) have originated from southern Africa while South Australian populations (subsp. europaea) have mostly derived from western or central Mediterranean cultivars. Invasive populations of subsp. cuspidata showed significant loss of genetic diversity in comparison to a putative source population, and a recent bottleneck was evidenced in Hawaii. Conversely, invasive populations of subsp. europaea did not display significant loss of genetic diversity in comparison to a native Mediterranean population. Different histories of invasion were inferred for these two taxa with multiple cultivars introduced restoring gene diversity for europaea and a single successful founder event and sequential introductions to East Australia and then Hawaii for cuspidata. Furthermore, one hybrid (cuspidata Â europaea) was identified in East Australia. The importance of hybridizations in the future evolution of the olive invasiveness remains to be investigated.

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“…Associations between mtDNA haplotypes and sex expression have been found in natural populations of wild beets (Beta maritima, Cuguen et al 1994), plantains (P. lanceolata, De Haan et al 1997b), thyme (T. vulgaris, Belhassen et al 1993Manicacci et al 1996), and now bladder campion (S. vulgaris). Sex expression in S. vulgaris is cytonuclear (Charlesworth and Laporte 1998;Taylor et al 2001), and crossing studies using plants from the studied populations have detected the presence of multiple CMS factors that are statistically associated with different mtDNA haplotypes (Taylor et al 2001).…”

Section: Associations Between Sex Expression and Haplotypementioning

confidence: 99%

“…Theoretical investigations suggest that high frequencies of females can occur when their restorer frequencies are low (Frank 1989;Gouyon et al 1991). High frequencies of females can result from random processes such as those during founder events when a CMS type colonizes a new site and restorers are initially absent or in low frequency (Manicacci et al 1996). Population variation in sex ratio might therefore reflect the population genetic structure of genes controlling sex expression.…”

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Mitochondrial Dna Diversity, Population Structure, and Gender Association in the Gynodioecious Plant Silene Vulgaris

Olson

McCauley

2002

Evolution

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Abstract. A highly variable mitochondrial DNA (mtDNA) restriction fragment length polymorphism (RFLP) locus is used to assess the population structure of mitochondrial genomes in the gynodioecious plant Silene vulgaris at two spatial scales. Thirteen mtDNA haplotypes were identified within 250 individuals from 18 populations in a 20-km diameter region of western Virginia. The population structure of these mtDNA haplotypes was estimated as ST ϭ 0.574 (Ϯ 0.066 SE) and, surprisingly, genetic differentiation among populations was negatively correlated with geographic distance (Mantel r ϭ Ϫ0.246, P Ͻ 0.002). Additionally, mtDNA haplotypes were spatially clumped at the scale of meters within one population. Gender in S. vulgaris is determined by an interaction between autosomal male fertility restorers and cytoplasmic male sterility (CMS) factors, and seed fitness is affected by an interaction between gender and population sex ratio; thus, selection acting on gender could influence the distribution of mtDNA RFLP haplotypes. The sex ratio (females:hermaphrodites) varied among mtDNA haplotypes across the entire metapopulation, possibly because the haplotypes were in linkage disequilibrium with different CMS factors. The gender associated with some of the most common haplotypes varied among populations, suggesting that there is also population structure in male fertility restorer genes. In comparison with reports of mtDNA variation from other published studies, we found that S. vulgaris exhibits a large number of mtDNA haplotypes relative to that observed in other species.Key words. Caryophyllaceae, gene flow, genetic structure, mitochondrial DNA, seed dispersal, sex ratio, spatial structure.Received March 23, 2001. Accepted September 20, 2001 Genetic markers are commonly used to assess the effects of genetic drift and gene flow on structuring genetic diversity within and among populations (Slatkin 1985; Neigel 1997). When it is known that the frequency of genetic markers is influenced by selection, however, that influence on spatial structure must also be considered (Whitlock and McCauley 1999). One such case can be found in gynodioecious plant species in which gender is determined in part by cytoplasmic male sterility (CMS) factors that are located in the mitochondrial genome . CMS factors are maternally inherited and block the production of viable pollen. It has been suggested that the population structure of highly polymorphic mitochondrial DNA (mtDNA) restriction fragment length polymorphisms (RFLP) might reflect both the effects of selection and random processes on the dispersion of CMS genes in natural populations, if these mtDNA variants mark different CMS lineages (Olson and McCauley 2000).Approximately 7% of Angiosperm species exhibit gynodioecious breeding systems in which individuals are either female or hermaphroditic (Richards 1997). It has been known for nearly a century that the genetics underlying sex expression in gynodioecious species can be quite complex, involving an interaction between CMS factors a...

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Founder effects and sex ratio in the gynodioecious Thymus vulgaris L.

Cited by 66 publications

References 40 publications

Male‐biased hermaphrodites in a gynodioecious shrub,Daphne jezoensis

Male‐biased hermaphrodites in a gynodioecious shrub,Daphne jezoensis

On the origin of the invasive olives (Olea europaea L., Oleaceae)

Mitochondrial Dna Diversity, Population Structure, and Gender Association in the Gynodioecious Plant Silene Vulgaris

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