Flowering phenology: An example of relaxation of natural selection?

Ollerton, Jeff; Lack, Andrew

doi:10.1016/0169-5347(92)90175-b

Cited by 156 publications

(136 citation statements)

References 22 publications

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“…Nevertheless, in Piantago media flowering time causes effective reproductive isolation between sympatric diploid and tetraploid cytotypes (van Dijk et al, 1994). Flowering time displacement may be constrained by other selective forces acting on flowering time (Rathcke & Lacey 1985;Ollerton & Lack, 1992;Fox & Kelley, 1993). Pollinator phenology in animal pollinated species and the seasonal development of the vegetation in windpollinated plants may also restrict flowering time divergence.…”

Section: Resultsmentioning

confidence: 99%

Simulations of flowering time displacement between two cytotypes that form inviable hybrids

Dijk

Bijlsma

1994

Heredity

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The evolution of reproductive isolation by flowering time displacement between two cytotypes that produce inviable hybrids was studied by computer simulations in an isolation-by-distance model. Flowering time distribution was stabilized by mass-action, both by the mating procedure and by pollen-limited seed-production in early or late flowering plants. Coexistence had to last long enough for flowering time divergence to evolve. This could only be achieved in a mosaic of local patches or parapatry. The model showed that flowering time displacement occurred despite the stabilizing effect of mass-action and the restricted width of the interaction zone. Initially an inverse dine for flowering time was formed but after 200 generations this dine had become monotonic. In contrast to the possible swamping effect by gene flow from outside the zone, there was a spread of genes into the allopatric ranges.

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Section: Resultsmentioning

confidence: 99%

Simulations of flowering time displacement between two cytotypes that form inviable hybrids

Dijk

Bijlsma

1994

Heredity

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“…Por outro lado, as espécies apresentaram grande variação na expressão das fenofases reprodutivas ao longo do ano (San MartinGajardo 1999). Uma argumentação alternativa para explicar essa variação seria que as espécies estudadas não sofreram forte pressão seletiva, permitindo o surgimento ao acaso de distintos padrões, ou períodos dispersos de floração e frutificação ao longo do ano (Ollerton & Lack 1992). Para uma avaliação precisa dos fatores que regulam as fenofases seriam necessários estudos que registrassem individualmente variáveis como luz, temperatura e umidade em conjunto com informações sobre os agentes de polinização e de dispersão de frutos (por exemplo, diversidade e abundância dos animais e especificidade das relações planta-animal), associando-as com os dados fenológicos coletados.…”

Section: Rudgea Jasminoidesunclassified

Fenologia de Rubiaceae do sub-bosque em floresta Atlântica no sudeste do Brasil

Martin-Gajardo¹,

Morellato²

2003

Rev. bras. Bot.

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-(Phenology of understorey Rubiaceae in the Atlantic forest, southeastern Brazil). Phenological studies of different species within a single family occuring in the same habitat, may help to understand the possible factors regulating the phenophases. During 14 months, we observed the vegetative and reproductive phenological patterns of ten understorey species of Rubiaceae of a Brazilian Atlantic forest, Núcleo Picinguaba, São Paulo State, Brazil. Leaf production and leaf fall occurred simultaneously in all studied species, throughout the observation period, resulting an evergreen appearance to the understorey. Flowering was also observed along the year, althougth the number of species flowering was higher during the wettest and hotest season. Our result contrasts with the seasonal flowering pattern observed for canopy species of Rubiaceae at the same area. The correlations between rainfall, temperature and Rubiaceae flowering were not significant. The fruit production was distributed along the study period, increasing at the end of the rainy season, resulting in a continuous availability of resources for frugivores. Reproductive phenological patterns differed among the Rubiaceae species in such a way that different factors seem to be regulating the phenophases of each species.Key words -flowering, fruiting, phenological patterns, Psychotria, rain forest RESUMO -(Fenologia de Rubiaceae do sub-bosque em floresta Atlântica no sudeste do Brasil). A comparação da fenologia de diferentes espécies de uma família, ocorrendo no mesmo hábitat, pode auxiliar na compreensão dos fatores reguladores das fenofases. Os padrões fenológicos vegetativos e reprodutivos de dez espécies de Rubiaceae foram estudados durante 14 meses no sub-bosque de floresta Atlântica, Núcleo Picinguaba, Ubatuba, SP. A produção e queda de folhas ocorreram simultaneamente nas espécies estudadas e ao longo de todo o período de estudo, proporcionando ao sub-bosque uma aparência sempre verde. A floração foi pouco sazonal, com aumento no número de espécies durante o período de maior precipitação e temperatura, porém não apresentando correlações significativas com os fatores climáticos. Este resultado contrasta com o padrão de floração sazonal, correlacionado ao fotoperíodo e temperatura, observado nas espécies de Rubiaceae de dossel na mesma área. A produção de frutos ocorreu ao longo de todo período de estudo, com aumento no número de espécies com frutos maduros no final da estação chuvosa, resultando em disponibilidade constante desses frutos para frugívoros. Os padrões fenológicos reprodutivos diferiram entre as espécies, sugerindo que fatores distintos devem estar regulando a ocorrência das fenofases nestas espécies de Rubiaceae.

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“…2003; but see Ollerton & Lack 1992). Similarities in related groups may include flowering duration and intensity (Johnson 1992).…”

Section: Introductionmentioning

confidence: 99%

Family, visitors and the weather: patterns of flowering in tropical rain forests of northern Australia

Boulter¹,

Kitching²,

Howlett³

2005

Journal of Ecology

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Summary1 A data base on the flowering phenology of the Wet Tropics bioregion of far northern Queensland, Australia, has been constructed, based upon over 36 774 records from two Queensland-based herbaria. 2 Flowering patterns have been analysed against the predictions of three overlapping hypotheses based on climatic, biotic and phylogenetic explanations. No one hypothesis is supported to the exclusion of the others. 3 Patterns of flowering in the Wet Tropics show marked seasonal increases and decreases, except in the northern lowlands. In general this seasonality correlates with rainfall and temperature and is exacerbated by increasing latitude and altitude. 4 There is little or no statistical evidence for the over-dispersion of flowering times that would indicate a competition-avoidance mechanism: flowering within taxa or morphological groups tends to be clumped (and if not, is random). 5 That clumping of flowering within taxa does not coincide with a single season provides support for a mass action hypothesis based on the minimization of generalist predation and/or the avoidance of flower predation. 6 Timing of flowering did show some consistency among species within genera and within families, but there was little consistency at higher taxonomic levels. Clear separation of the biotic and phylogenetic hypotheses requires greater knowledge of pollination ecology and phylogeny of this large and diverse flora. 7 Understanding of flowering patterns and their underlying determining mechanisms is a key to assessing the ecosystem health of the forest. Our results highlight the importance of competitive interactions and of physical and evolutionary factors as determinants of flowering time, intensity and co-occurrence in tropical forests.

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Flowering phenology: An example of relaxation of natural selection?

Cited by 156 publications

References 22 publications

Simulations of flowering time displacement between two cytotypes that form inviable hybrids

Simulations of flowering time displacement between two cytotypes that form inviable hybrids

Fenologia de Rubiaceae do sub-bosque em floresta Atlântica no sudeste do Brasil

Family, visitors and the weather: patterns of flowering in tropical rain forests of northern Australia

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