Evolution of Dioecism in Lepechinia Willd. sect. Parviflorae (Lamiaceae)

Hart, Jeffrey A.

doi:10.2307/2418340

Cited by 44 publications

(37 citation statements)

References 12 publications

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“…In theory, androdioecy (loss of gynoecia in some plants) could be an intermediary, but this condition is extremely rare in angiosperms, and it is unclear whether it has ever given rise to dioecy (e.g., Swensen et al 1998). In contrast, gynodioecy is more common, and changes from hermaphroditism to dioecy through gynodioecy are well documented (e.g., Hart 1985;Weller et al 1998). Most important for this argument, selection models based on nuclear and nuclear-cytoplasmic male sterility (Schultz 1994) suggest that gynodioecy may be unstable and may result in accelerated transitions to dioecy.…”

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confidence: 99%

Phylogenetic Analysis of Dioecy in Monocotyledons

Weiblen

Oyama

Donoghue

2000

The American Naturalist

144

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Surveys of plant breeding systems in angiosperm families have shown a significant association between monoecy and dioecy, and researchers have proposed that dioecy has tended to evolve from monoecy. We evaluated this hypothesis in the context of a phylogeny of 918 monocotyledons assembled from 19 published trees. Binary and multistate breeding system characters were mapped onto a set of composite trees, and alternative models of character change were compared using maximum likelihood. Over a range of tree topologies and optimizations, we found three to eight times as many changes from hermaphroditism to dioecy as we did from monoecy to dioecy. Also, the rate at which monoecy gave rise to dioecy was not significantly higher than the rate at which hermaphroditism gave rise to dioecy. Our analysis implies that the correlation of monoecy and dioecy in angiosperm families does not reflect a preponderance of changes from monoecy to dioecy. Instead, we postulate that the family-level correlation results from the clustering of breeding system changes in the underlying phylogeny. Our results suggest renewed attention to modeling the transition from hermaphroditism to dioecy, possibly involving transient intermediates such as gynodioecy.

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confidence: 99%

Phylogenetic Analysis of Dioecy in Monocotyledons

Weiblen

Oyama

Donoghue

2000

The American Naturalist

144

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“…A stable polymorphism of female and hermaphrodite individuals, coined "gynodioecy" by Darwin (1877), is a likely intermediate stage in the evolution from hermaphroditism to dioecy in flowering plants (see Charlesworth and Charlesworth 1978;Hart 1985). This polymorphism requires a female superiority in ovule success, whose threshold minimum depends on the inheritance of male sterility.…”

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confidence: 99%

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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“…In the genus Lepechinia Willd. (Hart 1985) different sections are either hermaphrodite and gynodioecious or gynodioecious and dioecious. In this genus dioecy has probably evolved more than once from gynodioecy.…”

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confidence: 99%

The sexual status of Colebrookea (Labiatae)

Raza¹,

Ingrouille²

1997

Telopea

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[221][222][223][224][225]. The sexual status of Colebrookea Smith (Labiatae) has been investigated and found to be dioecious and sexually dimorphic. Male flowers have a small non-functioning ovary and long exserted stamens. Female flowers have small staminodes inserted inside the corolla, and a gynoecium in which only one mericarp matures. The corolla is smaller in female flowers and the calyx larger. The mericarp is released within the calyx. The fruiting calyx enlarges after pollination, with calyx lobes reduced to plumose teeth.

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Evolution of Dioecism in Lepechinia Willd. sect. Parviflorae (Lamiaceae)

Cited by 44 publications

References 12 publications

Phylogenetic Analysis of Dioecy in Monocotyledons

Phylogenetic Analysis of Dioecy in Monocotyledons

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

The sexual status of Colebrookea (Labiatae)

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