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Titolo:
SEX-RATIO VARIATION AND SPATIAL-DISTRIBUTION OF SIPARUNA-GRANDIFLORA,A TROPICAL DIOECIOUS SHRUB
Autore:
NICOTRA AB;
Indirizzi:
MACQUARIE UNIV,SCH BIOL SCI SYDNEY NSW 2109 AUSTRALIA UNIV CONNECTICUT,DEPT ECOL & EVOLUT BIOL STORRS CT 06269
Titolo Testata:
Oecologia
fascicolo: 1-2, volume: 115, anno: 1998,
pagine: 102 - 113
SICI:
0029-8549(1998)115:1-2<102:SVASOS>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
SILENE-LATIFOLIA CARYOPHYLLACEAE; SPINACIA-OLERACEA L; RAIN-FOREST; FEMALE PLANTS; OEMLERIA-CERASIFORMIS; CHAMAELIRIUM-LUTEUM; REPRODUCTIVE EFFORT; BIOMASS ALLOCATION; POPULATION BIOLOGY; VEGETATIVE GROWTH;
Keywords:
DIOECY; SEX RATIO; SPATIAL SEGREGATION; SIPARUNA; SEXUAL DIMORPHISM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
72
Recensione:
Indirizzi per estratti:
Citazione:
A.B. Nicotra, "SEX-RATIO VARIATION AND SPATIAL-DISTRIBUTION OF SIPARUNA-GRANDIFLORA,A TROPICAL DIOECIOUS SHRUB", Oecologia, 115(1-2), 1998, pp. 102-113

Abstract

Populations of dioecious plant species often exhibit biased sex ratios. Such biases may arise as a result of sex-based differences in life history traits, or as a result of spatial segregation of the sexes. Ofthese, sex-based differentiation in life history traits is likely to be the most common cause of bias. In dioecious species, selection can act upon the sexes in a somewhat independent way, leading to differentiation and evolution toward sex-specific ecological optima. I examinedsex ratio variation and spatial distribution of the tropical dioecious shrub Siparuma grandiflora to determine whether populations exhibited a biased sex ratio, and if so, whether the bias could be explained in terms of nonrandom spatial distribution or sex-based differentiationin life history traits. Sex ratio bias was tested using contingency tables, a logistic regression approach was utilized to examine variation in life history traits, and spatial distributions were analyzed using Ripley's K, a second-order neighborhood analysis. I found that although populations of S. grandiflora have a male-biased sex ratio within and among years, there was no evidence of spatial segregation of the sexes. Rather, the sex ratio bias was shown to result primarily from sex-based differentiation in life history traits; males reproduce at a smaller size and more frequently than females. The sexes also differ inthe relationship between plant size and reproductive frequency. Lightavailability was shown to affect reproductive activity in both sexes,though among infrequently flowering plants, females require higher light levels than males to flower. The results of this study demonstratethat ecologically significant sex-based differentiation has evolved in S. grandiflora.

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Documento generato il 31/03/20 alle ore 09:31:58