Reproductive Allocation and the Fitness Consequences of Selfing in Two Sympatric Species of Epilobium (Onagraceae) with Contrasting Mating Systems

Parker, Ingrid M.; Nakamura, Robert R.; Schemske, Douglas W.

doi:10.2307/2446230

Cited by 35 publications

(11 citation statements)

References 37 publications

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“…On the other hand, small flowers are often part of an evolved syndrome that includes automatic selfing (autogamy) mechanisms that can ameliorate conditions of low pollinator availability (Piper et al 1986;Rathcke and Real 1993;Parker et al 1995;Brunet and Eckert 1998). Higher levels of autogamy could release the small-flowered Genista from pollen limitation.…”

Section: Introductionmentioning

confidence: 99%

Comparative pollinator limitation of two non-native shrubs: do mutualisms influence invasions?

Parker

Haubensak

2002

Oecologia

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While interactions between invaders and resident species have received a great deal of attention recently, the role of mutualists in facilitating or constraining invasions is rarely considered. We investigated the reproductive ecology of two closely related, woody legumes, Cytisus scoparius (Scotch broom) and Genista monspessulana (French broom), invading the same sites. Both species are considered noxious non-native weeds in California, and are considered to be ecologically similar, but Genista has much smaller flowers than Cytisus. Neither species showed appreciable levels of autogamous selfing. When experimentally self-pollinated, Genista demonstrated less depression of fruit set and seed set relative to outcrossed flowers than did Cytisus. At two sites on the Marin peninsula, Calif., Genista flowers were consistently less likely to be pollinated than Cytisus flowers. Genista was significantly pollen limited at both sites, while Cytisus was pollen limited at only the site with lower visitation rates. In the three populations with demonstrable pollen limitation, we found a significant relationship between fruit production and natural pollinator visitation at the level of the individual plant. However, we did not find that overall patterns of fecundity were strongly predicted by differences in pollen limitation between species or between sites. While a previous study found a tight link between patterns of pollinator visitation and patterns of reproduction in Cytisus in Washington State, we conclude that a more complex and variable environment (in terms of resources, herbivores, and florivores) on the Marin Peninsula de-coupled the relationship between pollinators and fruit production in these invaders. Our results suggest that the role of mutualisms in promoting or constraining invasions is likely to vary considerably among invaded communities.

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Section: Introductionmentioning

confidence: 99%

Comparative pollinator limitation of two non-native shrubs: do mutualisms influence invasions?

Parker

Haubensak

2002

Oecologia

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“…Inbreeding depression, the reduced fitness of progeny derived from inbreeding relative to outbreeding, is an important selective force governing the evolution of plant sexual systems (Darwin, 1876;Lloyd, 1979;INBREEDING DEPRESSION IN E. ANGUS TIFOLIUM 207 support for the negative correlation predicted between inbreeding depression and selfing rate (Husband & Schemske, 1995), there are still relatively few studies that relate inbreeding depression to the mating system or to other measures of the history of inbreeding (Toppings, 1989;Holtsford & Elistrand, 1990;Parker et al, 1995). Furthermore, most studies have focused on the magnitude of inbreeding depression at the level of the population and relatively little attention has been paid to the timing of inbreeding depression through the life cycle or to variation in its magnitude among plants within populations, both of which have a direct bearing on the potential for the evolution of inbreeding depression.…”

Section: Introductionmentioning

confidence: 99%

Magnitude and timing of inbreeding depression in a diploid population of Epilobium angustifolium (Onagraceae)

1995

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Evolutionary theory predicts a negative correlation between the rate of self-fertilization and the magnitude of inbreeding depression in natural plant populations. We examined the mating system and inbreeding depression at four life stages in a diploid population of Epilobium angustifolium (Onagraceae). The multilocus rate of self-fertilization, inferred from the segregation of allozymes at two polymorphic loci (Pgi-2, Mdh-2) among seedlings from 22 open-pollinated plants, was 0.06 (SE± 0.10). However, after adjusting for differential mortality of selfed progeny prior to the seedling stage, the selfing rate was 0.45. The parental inbreeding coefficient (F) was -0.26 (SE 0.103) indicating more heterozygotes than in a randomly mating population. The magnitude of inbreeding depression at seed maturation, seed germination, juvenile survival and dry mass at 8 weeks was measured in a greenhouse experiment. Thirty-four plants, grown from open-pollinated seed, were each self-fertilized and randomly outcrossed. We observed significant inbreeding depression at all four stages, although its magnitude differed significantly among maternal plants and among stages. Inbreeding depression was largest during seed maturation (0.87), where seed-set in outcrossed flowers (65.7 per cent) was eight times higher than in selfed flowers (8.3 per cent). Inbreeding depression for dry mass after 8 weeks (0.50) was at least twice that for germination (0.25) and survival (0.15). The magnitude of inbreeding depression for each of the 34 maternal parents was not significantly correlated across life stages, suggesting that its genetic basis varies across the life cycle. Our results indicate that E. angustifolium exhibits high levels of inbreeding depression, much of which is expressed early in the life cycle, during seed maturation, consistent with results for other long-lived, outcrossing species. However, given its moderate rate of self-fertilization, the total inbreeding depression (0.95) maintained in E. angustifolium is very high in comparison to other angiosperms.

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“…Its magnitude in natural populations differs greatly among species and sometimes among populations within species. This variation, both in severity of depression and in its ontogenetic timing, has been related to differences in the mating system, particularly the degree of selfing (Charlesworth and Charlesworth 1987;Lande et al 1994;Latta and Ritland 1994;Parker et al 1995;Husband and Schemske 1996). The review by Husband and Schemske (1996) is recent and thorough, and the reader is referred to it for details.…”

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confidence: 99%

Relationship Between Self-Fertility, Allocation of Growth, and Inbreeding Depression in Three Coniferous Species

Sorensen

1999

Evolution

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Abstract.-Mortality and growth of self and outcross families of three wind-pollinated, mixed-mating, long-lived conifers, Douglas-fir (Pseudotsuga menziesiii, ponderosa pine (Pinus ponderosa), and noble fir (Abies procera) were followed from outplanting to age 26 (25 for noble fir) in spaced plantings at a common test site. Response to inbreeding differed greatly among species over time and in all regards. Only Douglas-fir and noble fir will be contrasted here, because ponderosa pine usually was intermediate to the other two in its response to inbreeding. In earlier reports, compared to noble fir Douglas-fir had a higher rate of primary selfing and larger inbreeding depression in seed set. Douglas-fir continued to have higher inbreeding depression in nursery and early field survival. The species differed in time courses of inbreeding depression in height and in allocation of growth due to crowding. Between ages 6 and 12, the relative elongation rate (dm . dm-1 • yr") of Douglas-fir was significantly greater in the selfs than in the outcrosses. The response was not observed in noble fir. At final measurement, inbreeding depression in diameter relative to inbreeding depression in height was greater in Douglas-fir than in noble fir. At final measurement inbreeding depression in height was inversely related to inbreeding depression in survival. Cumulative inbreeding depressions from time of fertilization to final measurement were 0.98, 0.94, and 0.83 for Douglas-fir, ponderosa pine, and noble fir, respectively, which indicates that selfs will not contribute to the mature, reproductive populations.Key words.-Abies procera, Douglas-fir, inbreeding depression, noble fir, photomorphogenic effects, Pinus ponderosa, ponderosa pine, Pseudotsuga menziesii.Received January 28, 1998. Accepted November 12, 1998 Inbreeding depression (ID) is the reduction in fitness associated with increased homozygosity. Its magnitude in natural populations differs greatly among species and sometimes among populations within species. This variation, both in severity of depression and in its ontogenetic timing, has been related to differences in the mating system, particularly the degree of selfing (Charlesworth and Charlesworth 1987;Lande et al. 1994;Latta and Ritland 1994;Parker et al. 1995;Husband and Schemske 1996). The review by Husband and Schemske (1996) is recent and thorough, and the reader is referred to it for details.The theoretical expectation is that high rates of primary selfing (selfing at the fertilization stage) will purge highly deleterious alleles (Lande and Schemske 1985;Charlesworth and Charlesworth 1987). Within-and among-species comparisons do indeed indicate that ID in embryo and neonatal survival and growth traits are negatively related with rate of primary selfing (Latta and Ritland 1994;Husband and Schemske 1996). However, the relationship also shows large variation around the regression line. This indicates that factors such as degree of dominance or complex modes of inheritance, magnitude of effect, genomic mutatio...

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Reproductive Allocation and the Fitness Consequences of Selfing in Two Sympatric Species of Epilobium (Onagraceae) with Contrasting Mating Systems

Cited by 35 publications

References 37 publications

Comparative pollinator limitation of two non-native shrubs: do mutualisms influence invasions?

Comparative pollinator limitation of two non-native shrubs: do mutualisms influence invasions?

Magnitude and timing of inbreeding depression in a diploid population of Epilobium angustifolium (Onagraceae)

Relationship Between Self-Fertility, Allocation of Growth, and Inbreeding Depression in Three Coniferous Species

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