Sex Allocation and Outcrossing Rate: A Test of Theoretical Predictions Using Bromegrasses (Bromus)

McKone, Mark

doi:10.2307/2409260

Cited by 34 publications

(25 citation statements)

References 34 publications

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“…All variation was observed as single-banded electrophoretic variants attributed to allozymes, indicating that selfing is characteristic of all diploids examined. This is in accordance with other data on autogamy and self-fertilization of Genea bromes (SMITH 1970;MCKONE 1985MCKONE , 1987NO-VAK et al 1991).…”

Section: Resultssupporting

confidence: 93%

Bromus fasciculatus Presl - a third diploid progenitor of Bromus section Genea allopolyploids (Poaceae)

Oja

2002

Hereditas

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Allozyme variation of ten heterozymes of seven enzymes among five accessions of a rare diploid Bromus fasciculatus was analysed with the use of PAGE and compared with that for six other species of section Genea of the genus Bromus. Allozymes charasteristic for diploids B. tectorum and B. fasciculatus are combined in fixed heterozygous phenotypes of tetraploid B. rubens. Fixed heterozygous phenotypes of tetraploid B. madritensis combine one allozyme of B. fasciculatus with another of diploid B. sterilis at each of the loci studied. Of the three diploids studied, only B. sterilis fits well for a role of a genome donor for the polyploid B. diandrus-rigidus complex. Bromus fasciculatus thus appears to be a diploid ancestor for the two tetraploids of section Genea, B. rubens and B. madritensis.

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Section: Resultssupporting

confidence: 93%

Bromus fasciculatus Presl - a third diploid progenitor of Bromus section Genea allopolyploids (Poaceae)

Oja

2002

Hereditas

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“…ductive assurance in autogamous selfers also reduces the benefit of attractive structures for female fitness, as pollinators are not required for fertilization. Studies ofpollenovule ratios (Cruden, 1977;Preston, 1986;Vasek and Weng, 1988), male allocation (Schoen, 1982;Cruden and Lyon, 1985;Charnov, 1987;McKone, 1987), and allocation to attraction (Ritland and Ritland, 1989;Lyons and Antonovics, 1991) confirm the broad-scale patterns predicted for selfing and outcrossing taxa. However, few studies have measured both sex allocation and mating system in closely related, co-occurring taxa.…”

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confidence: 59%

Reproductive allocation and the fitness consequences of selfing in two sympatric species ofEpilobium(Onagraceae)with contrasting mating systems

Parker

Nakamura

Schemske

1995

American J of Botany

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Selfing has evolved repeatedly in outcrossing taxa, and theory predicts that an increase in the level of self‐fertilization should occur in concert with changes in reproductive allocation and the magnitude of inbreeding depression. Here we characterize the mating system of two sympatric congeners, Epilobium ciliatum and E. angustifolium, and compare the taxa for 1) reproductive allocation patterns and 2) the fitness consequences of self‐fertilization. For E. ciliatum, autogamy rates were high, pollinator visitation was low, and electrophoresis revealed no genetic variation at 11 putative isozyme loci. For E. angustifolium, autogamy rates were low, pollinator visitation was relatively high, and electrophoresis generated an outcrossing rate estimate of t = 0.64 (SE = 0.08). The pollen/ovule ratio was ten times higher for E. angustifolium than for E. ciliatum, due to a decline in pollen production in the selfing species. The proportion of total flower biomass allocated to female function was significantly greater in E. ciliatum, while that allocated to male function and attractive structures was greater in E. angustifolium. We quantified the fitness consequences of selfing at three life stages: seed number, percent germination, and mature biomass. Relative performance (RP) measures indicated less inbreeding depression for E. ciliatum than for E. angustifolium at all stages; differences in RP between the species were significant for seed number and cumulative total, but not for germination or biomass. RP was correlated among life history stages for only one comparison, suggesting that the genetic basis of inbreeding depression differs among life history stages. Variation among maternal parents for RP was significant at almost all stages in both species, with the exception of seed number in E. ciliatum. The striking variation among maternal parents in E. angustifolium, ranging from strong inbreeding depression to strong outbreeding depression, may reflect both variation in the history of inbreeding and the long‐distance migration of individuals from different populations.

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“…Most studies, however, use biomass alone as an estimate of reproductive allocation, which may be problematic if tissues differ greatly in their building costs. However, McKone (1987) found that estimates of sex allocation in several grass species were quite robust when different resource currencies were used (i.e. energy content and ®ve different nutrients).…”

Section: Overall Sex Allocationmentioning

confidence: 99%

Size-dependent sex allocation in a simultaneous hermaphrodite parasite

Schärer

Karlsson

Christen

et al. 2001

Journal of Evolutionary Biology

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Most models of sex allocation distinguish between sequential and simultaneous hermaphrodites, although an intermediate sexual pattern, size‐dependent sex allocation, is widespread in plants. Here we investigated sex allocation in a simultaneous hermaphrodite animal, the tapeworm Schistocephalus solidus, in which adult size is highly variable. Sex allocation was determined using stereological techniques, which allow measuring somatic and reproductive tissues in a common currency, namely volume. We investigated the relationships between individual volume and allocation to different reproductive tissues using an allometric model. One measure of female allocation, yolk gland volume, increased more than proportionally with individual volume. This is in contrast to the measure of male allocation, testis volume, which showed a strong tendency to increase less than proportionally with individual volume. Together these patterns led to sex allocation being strongly related to individual volume, with large individuals being more biased towards female allocation. We discuss these findings in the light of current ideas about size‐dependent sex allocation in, primarily, plants and try to extend them to simultaneous hermaphrodite animals.

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Sex Allocation and Outcrossing Rate: A Test of Theoretical Predictions Using Bromegrasses (Bromus)

Cited by 34 publications

References 34 publications

Bromus fasciculatus Presl - a third diploid progenitor of Bromus section Genea allopolyploids (Poaceae)

Bromus fasciculatus Presl - a third diploid progenitor of Bromus section Genea allopolyploids (Poaceae)

Reproductive allocation and the fitness consequences of selfing in two sympatric species ofEpilobium(Onagraceae)with contrasting mating systems

Size-dependent sex allocation in a simultaneous hermaphrodite parasite

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