Sex Ratio in the Tropical Tree Triplaris americana (Polygonaceae)

Melampy, Michael N.; Howe, Henry F.

doi:10.2307/2407449

Cited by 53 publications

(57 citation statements)

References 17 publications

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“…In contrast, forest understory light environments are both spatially and temporally variable (e.g., Chazdon et al 1996). This may explain why woody understory species like S. grandi¯ora are less likely to demonstrate SSS (e.g., Bawa and Opler 1977;Melampy and Howe 1977;Hancock and Bringhurst 1980;Bullock 1982;Armstrong and Irvine 1989) (but see Cox 1981 where segregation according to soil nutrient content occurs).…”

Section: Sex Ratio and Spatial Distributionmentioning

confidence: 99%

Sex ratio variation and spatial distribution of Siparuna grandiflora , a tropical dioecious shrub

Nicotra

1998

Oecologia

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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. Of these, 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 examined sex ratio variation and spatial distribution of the tropical dioecious shrub Siparuna grandiflora to determine whether populations exhibited a biased sex ratio, and if so, whether the bias could be explained in terms of non-random spatial distribution or sex-based differentiation in 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 in the relationship between plant size and reproductive frequency. Light availability 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 demonstrate that ecologically significant sex-based differentiation has evolved in S. grandiflora.

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Section: Sex Ratio and Spatial Distributionmentioning

confidence: 99%

Sex ratio variation and spatial distribution of Siparuna grandiflora , a tropical dioecious shrub

Nicotra

1998

Oecologia

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“…The female biased sex ratio among flowering individuals in populations of Triplaris observed by several collectors was studied by Melampy and Howe (1977). Their conclusion was, that sex-dependent mortality was the basis for the female bias.…”

Section: Pollinationmentioning

confidence: 99%

A revision of the genus Triplaris (Polygonaceae)

Brandbyge

1986

Nordic Journal of Botany

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A revision of the genus niplark (Polygonaceae) John Brandbyge Brandbyge, J. 1986. A revision of the genus Piptaris (Polygonaceae). -Nord. J. Bot. 6: 545-570. Copenhagen. ISSN 0107-055X. The neotropical genus Triplaris Loefl. ex L. is revised. A total of 73 taxa had previously been described. In the present revision 17 species, 1 subspecies, and 1 variety are recognized. A new combination Triplaris melaenodendron (Bertol.) Standl. & Steyenn. ssp. colombiana (Meisner) Brandbyge is made, and a new variety T. setosa Rusby var. woyfkowski Brandbyge is proposed. Keys based on both pistillate and staminate specimens are presented.

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“…Many of the observed patterns of sexual differentiation in dioecious plants (e.g. lower female longevity, growth rate, size, or vegetative propagation, later female flowering, or microsite differentiation) have been interpreted as being the result of a presumed higher cost of reproduction in females (Putwain and Harper, 1972;Lloyd, 1973;Lysova and Khizhnyak, 1975;Freeman et al, 1976;Lloyd and Webb, 1977;Melampy and Howe, 1977).…”

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confidence: 99%