VARIATION IN MALE REPRODUCTIVE INVESTMENT AND MALE REPRODUCTIVE SUCCESS IN WHITE SPRUCE

An experimental population composed of ramets of white spruce clones was studied to determine the influence of different levels of clonal male reproductive investment on clonal male reproductive success, where the male reproductive success of different clones in the population was defined as the proportion of the seed crop sired by each clone. We present a multilocus estimation procedure which provides unbiased estimates of the proportion of seed sired by each parental genotypic class from pollen gamete frequency data, whenever gametic segregation frequencies are known. Significant linear and quadratic components were found for the relationship between the number of male cones produced and the estimated proportion of the seed crop sired. A clone that produced an exceptionally large number of male cones, however, did not have the greatest male reproductive success. In general, the results support an assumption made in theoretical models of selection on mating system modifiers regarding the relationship between male investment and male reproductive success. They also support the hypothesis that male reproductive success in wind-pollinated species continues to increase substantially with increasing male reproductive investment.     

REPRODUCTIVE CHARACTER DISPLACEMENT IN PHLOX

Plants of the red- and pink-flowered P. drummondii were introduced into a natural population of P. cuspidata. Their seeds were progeny-tested, and the percentage hybrid seed determined for each variant. Thirty-eight percent of the seed from the pink variant were hybrid compared to 13% of the red. The difference in hybrid production is best explained by corolla color. The self- and cross-compatibility of nine sympatric and nine allopatric populations were studied in the greenhouse. On the average, sympatric populations are more self-compatible than allopatric populations. Pollen germination is 13.7% vs. 7.3%, the difference being statistically significant. The self-compatibility differential was accompanied by a self seedset differential. On the average, sympatric populations are more cross-compatible with P. cuspidata than are allopatric populations. The germination of P. cuspidata pollen on sympatric P. drummondii stigmas was 13.3% vs. 9.8% on allopatric stigmas. However, the difference is not statistically significant. The presence of P. cuspidata has promoted reproductive character divergence in P. drummondii. The shift in corolla color and the increase in self-compatibility reduce the potential for gametic wastage and interspecific hybridization.     

CYTOLOGY AND REPRODUCTIVE CHARACTERISTICS IN PENNISETUM SETACEUM

A green ecotype of fountaingrass, Pennisetum setaceum (Forsk.) Chiov., was found to be triploid (3x = 27) with 9 II + 9 I at metaphase I. Meiotic behavior of the bivalents was normal, but the univalents lagged and divided precociously at anaphase I. The univalent halves lagged at anaphase II and were distributed at random. Micronuclei were common, and stainable pollen was approximately 40%. The green type produced four progeny with 54 chromosomes. A purple strain of P. setaceum was found to be hexaploid (6x = 54) with varying chromosomal associations. Meiotic behavior was highly irregular and stainable pollen was almost zero. Megasporogenesis was initiated in both types, but the megaspores degenerated and nucellar and integument cells developed into four-nucleate, aposporous embryo sacs. Following self-pollination, the green type set approximately 10% seed and the purple type set 0.05% seed. Purple fountaingrass set as high as 18% seed following the application of pollen from Pennisetum ciliare (L.) Link (4x = 36), exemplifying a rare form of pseudogamy between two species. Improvement of P. setaceum through a standard breeding program appears unlikely.     

害虫区域测报技术

大多数农作物害虫都是高度活动的,它们的数量和造成的为害在时间和空间上都大不一样,季节活动型和造成的为害率也因地域和年份而异.要预测害虫在一个区域范围的出现、数量、种群趋势和潜在为害,就要建立完善的监测体系.多年定点观测记录对于区域害虫预测来说是最基本的资料条件.与此同时,通过数学方法把害虫的发生与相关因子以数量化的形式表示出来,并在此基础上建立中长期预测模型是至关重要的.为了及时处理和传递虫情信息,计算机数据管理技术和网络技术将为此提供最重要的技术支撑.本文通过一些典型的应用实例,讨论了监测技术,预测模型,GIS技术,数据管理技术以及网络技术在区域害虫预测中的应用.     

ANATOMY OF THE REPRODUCTIVE BRACTS IN WELWITSCHIA

Rodin, Robert J. (Calif. State Polytechnic Coll., San Luis Obispo.) Anatomy of the reproductive bracts in Welwitschia . Amer. Jour. Bot. 50 (7): 641–648. Illus. l963.—The anatomy, including venation patterns, of the nodal bracts, sterile cone bracts, and fertile cone bracts of male and female cones is discussed. Two traces which dichotomize are present in each member. Occasional anomalous traces in the perianth have been discovered. Details of sclereids, fibers and gum canals are given. The connate nature of the bracts is described. The homologies of these organs are suggested.     

ENERGY DISTRIBUTION IN REPRODUCTIVE STRUCTURES OF AMARYLLIS

Energy content of tissue produced in male and female reproductive structures as well as in associated flower parts of Amaryllis was measured with an oxygen bomb calorimeter. In typical flowers, 6.6% of their total energy (2,880 cal) was in pollen, 4.9% in anther walls, 4.6% in ovules and placentae, and 12.6% in ovary walls and septa. Ovules were estimated to contain only about one-third as much energy as pollen. Mature seeds typically contained about 100 times as much energy as ovules. Total energy in mature seeds per flower was approximately equal to total energy in flower tissues. Proportional allocation of anther energy to pollen increased with anther size. The biological significance of these results is discussed.     

MODE OF SWARMING IN RELATION TO REPRODUCTIVE ISOLATION IN MAYFLIES

Mayfly males swarm, that is they fly in a fixed pattern by a specific object, the swarm marker. Females orientate to the same markers. Leptophlebia marginata mayflies were observed to orientate to two kinds of objects in a single locality in central Finland: to trees and to horizontal pale objects on the ground; when dispersed or moved to the other type of marker, they returned to their former orientation. Tree swarming is by far the most common mode of swarming, but some horizontally orientating populations were found. Sympatric populations are genetically and morphologically distinct, whereas other populations appear to have some gene flow between the swarming types. The tree-swarming mode appears to be primitive and the horizontal mode derived; wind rather than predation is the factor favoring swarming close to the ground. Swarming constitutes an effective mechanism of premating isolation in mayflies.