SEX ALLOCATION IN THE MONOECIOUS HERB BEGONIA-SEMIOVATA

被引:37
作者
AGREN, J [1 ]
SCHEMSKE, DW [1 ]
机构
[1] UNIV WASHINGTON, DEPT BOT, KB-15, SEATTLE, WA 98195 USA
关键词
BEGONIA SEMIOVATA; GENETIC CORRELATION; GENETIC VARIATION; MONOECY; REPRODUCTIVE CHARACTERS; SEX ALLOCATION;
D O I
10.1111/j.1558-5646.1995.tb05964.x
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
Sex-allocation models predict that the evolution of self-fertilization should result in a reduced allocation to male function and pollinator attraction in plants. The evolution of sex allocation may be constrained by both functional and genetic factors, however. We studied sex allocation and genetic variation for floral sex ratio and other reproductive traits in a Costa Rica population of the monoecious, highly selfing annual Begonia semiovata. Data on biomass of floral structures, flower sex ratios, and fruit set in the source population were used to calculate the average proportion of reproductive allocation invested in male function. Genetic variation and genetic correlations for floral sex ratio and for floral traits related to male and female function were estimated from the greenhouse-grown progeny of field-collected maternal families. The proportion of reproductive biomass invested in male function was low (0.34 at flowering, and 0.07 for total reproductive allocation). Significant among-family variation was detected in the size (mass) of individual male and female flowers, in the proportion of male Rowers produced, and in the proportion of total flower mass invested in male flowers. Significant among-family variation was also found in flower number per inflorescence, petal length of male and female flowers, and petal number of female flowers. Except for female petal length, we found no difference in the mean value of these characters between selfed and outcrossed progeny, indicating that, with the possible exception of female petal length, the among-family variation detected was not the result of variation among families in the level of inbreeding. Significant positive phenotypic and broad-sense genetic correlations were detected between the mass of individual male and female flowers, between male and female petal length, and between number of male and number of female flowers per inflorescence. The ratio of stamen-to-pistil mass (0.33) was low compared to published data for autogamous species with hermaphroditic flowers, suggesting that highly efficient selfing mechanisms may evolve in monoecious species. Our results indicate that the study population harbors substantial genetic variation for reproductive characters. The positive genetic correlation between investment in male and female flowers may reflect selection for maximum pollination efficiency, because in this self-pollinating species.
引用
收藏
页码:121 / 130
页数:10
相关论文
共 64 条
[1]  
AGREN J, 1993, EVOLUTION, V47, P125, DOI 10.2307/2410123
[2]   POLLINATION BY DECEIT IN A NEOTROPICAL MONOECIOUS HERB, BEGONIA-INVOLUCRATA [J].
AGREN, J ;
SCHEMSKE, DW .
BIOTROPICA, 1991, 23 (03) :235-241
[3]   VARIATION IN FLORAL SEX ALLOCATION WITH TIME OF SEASON AND CURRENCY [J].
ASHMAN, TL ;
BAKER, I .
ECOLOGY, 1992, 73 (04) :1237-1243
[4]  
BAWA KS, 1983, EVOLUTION, V37, P1271, DOI 10.1111/j.1558-5646.1983.tb00243.x
[5]  
BECKEN WA, 1984, MANUAL QUANTITATIVE
[6]  
Burt-Utley K., 1985, TULANE STUD ZOOL BOT, V25, P1
[7]   VARIATION IN SEX ALLOCATION AND FLORAL MORPHOLOGY IN IPOMOPSIS-AGGREGATA (POLEMONIACEAE) [J].
CAMPBELL, DR .
AMERICAN JOURNAL OF BOTANY, 1992, 79 (05) :516-521
[8]  
CHARLESWORTH B, 1990, EVOLUTION, V44, P520, DOI 10.1111/j.1558-5646.1990.tb05936.x
[9]   ALLOCATION OF RESOURCES TO SEX FUNCTIONS IN FLOWERING PLANTS [J].
CHARLESWORTH, D ;
MORGAN, MT .
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, 1991, 332 (1262) :91-102
[10]   THE EFFECT OF INVESTMENT IN ATTRACTIVE STRUCTURES ON ALLOCATION TO MALE AND FEMALE FUNCTIONS IN PLANTS [J].
CHARLESWORTH, D ;
CHARLESWORTH, B .
EVOLUTION, 1987, 41 (05) :948-968