Mixed Mating in Banksia brownii Baxter ex R. Br. (Proteaceae)

Sampson, JF; Collins, BG; Coates, D. J.

doi:10.1071/bt9940103

Cited by 25 publications

(29 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Banksia oligantha and B. ilicifolia were also lower at the species level, while values for B. cuneata were more comparable (A, 2.22; P, 65.0%; H e , 0.177; Hamrick et al 1992). The low levels observed, however, appear to be consistent with estimates for species from various proteaceous genera such as Banksia (Coates and Sokolowski 1992;Carthew 1993;Sampson et al 1994), Grevillea (Ayre et al 1994), Persoonia (Krauss 1997) and Lambertia (Coates and Hamley 1999).…”

Section: Discussionsupporting

confidence: 73%

Genetic divergence among and diversity within two rare Banksia species and their common close relative in the subgenusIsostylis R.Br. (Proteaceae)

Broadhurst¹,

Coates²

2004

Conservation Genetics

View full text Add to dashboard Cite

The Banskia subgenus Isostylis complex is comprised of two rare and restricted species, B. cuneata and B. oligantha, and the widespread B. ilicifolia. Population genetic structure and genetic diversity were examined within and among the three species using 10 allozyme loci across 21 populations. Levels of genetic diversity did not appear to correspond with either population size or geographic distribution. The restricted species B. cuneata exhibited the highest levels of gene diversity (H es , 0.13) followed by the widespread B. ilicifolia (H es , 0.10) and the other restricted species B. oligantha (H es , 0.08). Similarly, there was no relationship between genetic structure and geographical distribution with the rare B. cuneata being highly structured (h ¼ 0.370) compared with B. ilicifolia (h ¼ 0.164) and B. oligantha (h ¼ 0.221). The relatively low but similar levels of diversity present in the subgenus concur with those observed in other proteaceous genera and probably reflect historical events rather than a genetic effects associated with a recently fragmented landscape.

show abstract

Section: Discussionsupporting

confidence: 73%

Genetic divergence among and diversity within two rare Banksia species and their common close relative in the subgenusIsostylis R.Br. (Proteaceae)

Broadhurst¹,

Coates²

2004

Conservation Genetics

View full text Add to dashboard Cite

show abstract

“…A simulation of the effect of spatial and temporal variation in fire regimes on the population viability of a Banksia species showed that when fire frequency is high, the population extinction probability increases (Bradstock et al 1996). Sampson et al (1994) found low outcrossing rates for populations of Banksia brownii and suggested that frequent events of fire may have decreased plant density and outcrossing rate within population. Outcrossing rate in different plant density areas -The population of Helicteres sacarolha showed significant variation in outcrossing rate for two different plant density patches in 1994 (table 3).…”

Section: Discussionmentioning

confidence: 99%

“…Sampson et al (1994) suggested that low outcrossing rates found for populations of Banksia brownii Baxter ex R. Br. could be associated with frequent events of fire.…”

Section: Introductionmentioning

confidence: 99%

The post-fire effects on the outcrossing rate of a Brazilian savannah shrub, Helicteres sacarolha A.St.-Hil

Franceschinelli

Bawa

2005

Rev. bras. Bot.

View full text Add to dashboard Cite

-(The post-fire effects on the outcrossing rate of a Brazilian savannah shrub, Helicteres sacarolha A.St.-Hil.). The effect of post-fire, plant density and number of flowers per plant on outcrossing rates was examined in a Brazilian savannah shrub, Helicteres sacarolha. Data on number of flowering plants and flowers per plant were collected during the flowering season in January and February of 1994. In October of 1994, a fire swept through the studied area after 30 years of fire absence. The burnt plants of H. sacarolha resprouted, producing flowers and fruits in 1995. Seeds from several plants in both years were collected. Allozyme markers were used to estimate the multilocus outcrossing rates for 1994 and 1995 progenies. After the fire, outcrossing rates increased. In 1995, plants flowered vigorously, increasing flower density and probably pollinator activity. Helicteres sacarolha seems to be fire resistant, like other plant species of the Brazilian savannah, but several plants tagged in 1994 were not found after the fire, and may have died. Thus, although genetic diversity and outcrossing rates increased following the fire in 1994, repeated events of fire may decrease drastically the population size of H. sacarolha, leading to a diminished genetic diversity and outcrossing rates.Key words -cerrado, flower density, Helicteres, plant outcrossing rate, post-fire effect RESUMO -(Os efeitos pós-fogo na taxa de cruzamento de um arbusto do cerrado, Helicteres sacarolha A.St.-Hil.). Os efeitos do fogo, da densidade de plantas, do número de flores por planta na taxa de cruzamento foram checados para uma espécie de arbusto do cerrado, Helicteres sacarolha. Dados de número de plantas e flores por planta foram coletados durante o período de floração de janeiro a fevereiro de 1994. Em outubro de 1994, uma queimada ocorreu na área de estudo após 30 anos de ausência de fogo. No entanto, as plantas queimadas de H. sacarolha brotaram, produzindo flores e frutos em 1995. Sementes de várias plantas foram coletadas em 1994 e 1995. Marcadores aloenzimáticos foram utilizados para estimar a taxa de cruzamento para as progênies de 1994 e 1995. A taxa de cruzamento aumentou após a ocorrência do fogo. Em 1995, as plantas floresceram vigorosamente, aumentando a densidade de flores e, provavelmente, a atividade dos polinizadores entre as plantas da população. Como muitas espécies do cerrado brasileiro, H. sacarolha é tolerante ao fogo, contudo várias plantas marcadas em 1994 não foram encontradas após o fogo e podem ter morrido queimadas. Desta forma, eventos repetidos de fogo podem levar a uma drástica diminuição do tamanho da população de H. sacarolha e, conseqüentemente, a um decréscimo em suas taxas de diversidade genética e de cruzamento.Palavras-chave -cerrado, densidade de flor, efeito do fogo, Helicteres, taxa de cruzamento

show abstract

“…S. drummondii) or genotypic (e.g. B. brownii: Sampson et al 1994) plasticity in seed traits may experience stress or even extinction during extended climate change. Delayed reproductive maturity will reduce the number of generations that can establish from seed in any given time period therefore long-lived woody perennials with long primary juvenile periods such as B. brownii and species with low levels of fecundity are not expected to undergo rapid evolutionary adaptation (Jump & Peñuelas 2005).…”

Section: Geographic Range and Germination Nichementioning

confidence: 99%

Seed-based approach for identifying flora at risk from climate warming

Cochrane¹,

Daws

Hay

2010

Austral Ecology

View full text Add to dashboard Cite

In obligate seeding species, the germination niche is crucial for colonization and population survival. It is a high-risk phase in a plant's life cycle, and is directly regulated by temperature. Seeds germinate over a range of temperatures within which there is an optimum temperature, with thresholds above and below which no germination occurs. We suggest that abrupt changes in temperature associated with a warming climate may cause a disconnect between temperatures seeds experience and temperatures over which germination is able to occur, rendering obligate seeding species vulnerable to decline and extinction. Using a bidirectional temperature gradient system, we examined the thermal constraints in the germination niche of some geographically restricted species from the low altitude mountains of the Stirling Range, southern Western Australia, including seedlots from lowland populations of four of these species. We demonstrated that high temperatures are not a limiting factor for germination in some restricted species, signifying a lack of relationship between geographic range size and breadth of the germination niche. In contrast, we identified other restricted species, in particular Sphenotoma drummondii, as being at risk of recruitment failure as a consequence of warming: seeds of this species showed a strong negative relationship between percentage germination and increasing temperature above a relatively low optimum constant temperature (13°C). We found some ecotypic differences in the temperature profiles between seeds collected from montane or lowland populations of Andersonia echinocephala, and while specific populations may become more restricted, they are perhaps at less risk of extinction from climate warming.This seed-based approach for identifying extinction risk will contribute tangibly to efforts to predict plant responses to environmental change and will assist in prioritizing species for management actions, directing limited resources towards further investigations and can supplement bioclimatic modelling.

show abstract

Mixed Mating in Banksia brownii Baxter ex R. Br. (Proteaceae)

Cited by 25 publications

References 0 publications

Genetic divergence among and diversity within two rare Banksia species and their common close relative in the subgenusIsostylis R.Br. (Proteaceae)

Genetic divergence among and diversity within two rare Banksia species and their common close relative in the subgenusIsostylis R.Br. (Proteaceae)

The post-fire effects on the outcrossing rate of a Brazilian savannah shrub, Helicteres sacarolha A.St.-Hil

Seed-based approach for identifying flora at risk from climate warming

Contact Info

Product

Resources

About