ENHANCEMENT OF INBREEDING DEPRESSION BY DOMINANCE AND SUPPRESSION IN
            <i>IMPATIENS CAPENSIS</i>

Schmitt, Johanna; Ehrhardt, David

doi:10.1111/j.1558-5646.1990.tb05197.x

Cited by 160 publications

(83 citation statements)

References 40 publications

(41 reference statements)

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“…Because the magnitude of inbreeding depression tends to be positively associated with overall correlates of physiological stress (e.g., Waller 1985;Dudash 1990;Schmitt and Ehrhardt 1990), and physiological stress was minimized during the early stages of the plants in this study by daily watering of seedlings (during the first 2-3 weeks in flats and the first week in the field), these estimates of inbreeding depression probably err on the conservative side. Under natural conditions, seeds are set in April and May (and to a lesser extent from March to June), and germinate during the first extended rains of fall or winter, which may occur anytime between October and January.…”

Section: Environmental Effectsmentioning

confidence: 87%

Evolution of Unisexuality in the Hawaiian Flora: A Test of Microevolutionary Theory

Schultz

Ganders

1996

Evolution

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Abstract.-The evolution of separate sexes as a means of avoiding self-fertilization requires the controversial coexistence of large inbreeding depression and high selfing rate in the ancestral hermaphrodite population. Fitness components of adult females and hermaphrodites in nature, of their open-pollinated progeny, and of experimental selfs and outcrosses onto hermaphrodites were compared in endemic Hawaiian Bidens sandvicensis, all of whose known populations are gynodioecious, consisting of a mixture of females and hermaphrodites. Multilocus selfing rates of hermaphrodites were also estimated, and sex morph ratio monitored over four seasons in three populations of B. sandvicensis and one population of gynodioecious B. cervicata. Total mean inbreeding depression in seed set (in the glasshouse), germination rate (in an open-air nursery on Kauai), and first year survivorship and fecundity in the field were estimated as 0.94 (SE 0.04), and occurred primarily in drought months. Lower survivorship and fecundity of selfs were partially explained by their consistently smaller size. Open-pollinated seed of females had significantly lower germination rate, proportion flowering, and fecundity than outcrossed progeny of hermaphrodites, suggesting moderate biparental inbreeding in females and a lack of any non-outcrossing advantage to progeny of females. In all fitness components, open-pollinated progeny of hermaphrodites were inferior to those of females and to outcrosses, and in most components were superior to selfs. Total performance of open-pollinated progeny of females relative to those of hermaphrodites was calculated as 2.3 (SE = 0.4), but since inflorescences of females also set 20% to 50% more seed than those of hermaphrodites, their total relative ovule success was estimated as 3.2 (SE = 0.5). If inheritance of male sterility is nuclear, this superiority is sufficient to maintain females in frequencies over 20% in populations, whose actual frequencies ranged from 14% to 33%. In four populations, selfing rates of hermaphrodites, assayed in seedlings, were 0.50, 0.45, 0.25, and 0.30, but since substantial inbreeding depression occurred prior to germination, the mean selfing rate of hermaphrodite ovules exceeded 0.57. Female frequencies were significantly higher in the two populations with higher hermaphrodite selfing rate. These results suggest that inbreeding depression can exert a profound influence on the mating system of self-compatible plants on Hawaii and perhaps other oceanic islands, and can be sufficiently strong to electively favor the elimination of the male function.

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Section: Environmental Effectsmentioning

confidence: 87%

Evolution of Unisexuality in the Hawaiian Flora: A Test of Microevolutionary Theory

Schultz

Ganders

1996

Evolution

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“…It is commonly stated that growth in higherstress conditions will cause higher inbreeding depression, and several studies have indeed found increased inbreeding depression with lower light levels (Schemske 1983) or higher plant density (Schmitt and Ehrhardt 1990;Wolfe 1993). It is probably often the case, however, that outcrossed progeny will exhibit a proportionally greater response to increasing environmental quality.…”

Section: Inbreeding Depression At Different Life Stagesmentioning

confidence: 96%

CORRELATED EVOLUTION OF SELF-FERTILIZATION AND INBREEDING DEPRESSION: AN EXPERIMENTAL STUDY OF NINE POPULATIONS OFAMSINCKIA(BORAGINACEAE)

Johnston

Schoen

1996

Evolution

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Abstract.-The relation between inbreeding depression and rate of self-fertilization was studied in nine natural populations of the annual genus Amsinckia. The study included two clades (phylogenetic lineages) in which small-flowered, homostylous populations or species are believed to have evolved from large-flowered, heterostylous, self-compatible ones. In one lineage the small-flowered species is tetraploid with disomic inheritance. Rates of self-fertilization were 25% to 55% in the four large-flowered, heterostylous populations; 72% in a large-flowered but homostylous population; and greater than 99.5% in the four small-flowered, homostylous populations, which produce seed autonomously. When present, inbreeding depression occurred in the fertility but not the survival components of fitness. Using a cumulative fitness measure incorporating both survival and fertility (flower number), we found inbreeding depression to be lower in the four very highly self-fertilizing populations than in the five intermediate ones. The Spearman rank correlation between inbreeding depression and selfing rate for the nine populations was -0.50, but was not statistically significant (P = 0.12). Inbreeding depression was greater in the two tetraploid populations than in the very highly self-fertilizing, diploid ones. Phenotypic stability of progeny from self-fertilization tended to be higher in populations with lower inbreeding depression. We conclude that levels of self-fertilization and inbreeding depression in Amsinckia are determined more by other factors than by each other. Estimates of mutation rates and dominance coefficients of deleterious alleles, obtained from a companion study of the four highly self-fertilizing populations, suggest that a strong relationship may not be expected. We discuss the relationship of the present results to current theory of the coevolution of selffertilization and inbreeding depression.

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“…We may, however, also expect selection against selffertilisation, because self-fertilisation can lead to reduced ®tness compared to cross-fertilisation in both animals and plants (e.g. Charlesworth and Charlesworth, 1987;Jarne and Delay, 1990;Schmitt and Ehrhardt, 1990).…”

Section: Introductionmentioning

confidence: 99%

Lifetime reproductive output in a hermaphrodite cestode when reproducing alone or in pairs: a time cost of pairing

Schärer

Wedekind

1999

Evolutionary Ecology

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Abstract. The cestode Schistocephalus solidus is a facultatively self-fertilising simultaneous hermaphrodite. Here we test for di erences in the starting point, the rate, and the magnitude of egg production between individuals allowed to reproduce alone (only self-fertilisation possible) or in pairs (both self-and cross-fertilisation possible). Speci®cally, we want to distinguish between alternative processes responsible for the lower egg production in paired individuals observed in an earlier study (Wedekind et al., 1998). We designed an improved in vitro system, replacing the bird ®nal host that allows us to measure, with high temporal resolution, the timing and magnitude of lifetime egg production of worms in these two social situations. We found that the experimental groups did not di er signi®cantly in the starting point of egg production. However, the temporal pattern in egg production di ered between them, in that paired individuals had a lower rate of egg production. This, however, did not lead to a signi®cant reduction in lifetime egg production, as pairs compensated for the lower rate by producing eggs longer than single individuals. We argue that the lower rate of egg production may nevertheless lead to a time cost of pairing in the study species, and that this cost is likely to represent a cost of outcrossing due to sexual selection.

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ENHANCEMENT OF INBREEDING DEPRESSION BY DOMINANCE AND SUPPRESSION IN IMPATIENS CAPENSIS

Cited by 160 publications

References 40 publications

Evolution of Unisexuality in the Hawaiian Flora: A Test of Microevolutionary Theory

Evolution of Unisexuality in the Hawaiian Flora: A Test of Microevolutionary Theory

CORRELATED EVOLUTION OF SELF-FERTILIZATION AND INBREEDING DEPRESSION: AN EXPERIMENTAL STUDY OF NINE POPULATIONS OFAMSINCKIA(BORAGINACEAE)

Lifetime reproductive output in a hermaphrodite cestode when reproducing alone or in pairs: a time cost of pairing

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