马蹄香大小孢子发生及雌雄配子体形成

马蹄香（Ｓａｒｕｍａｈｅｎｒｙｉ,Ｏｌｉｖ．）花药壁的发育属双子叶型。花粉母细胞减数分裂为同时型,四分体主要为四面体形,少数为左右对称式排列。腺质绒毡层,其细胞可排列为不规则的两层,双核或多核。到单细胞花粉阶段,绒毡层细胞内切向壁上出现许多乌氏体。成熟花粉为２细胞型,圆球状,具单萌发沟。雌蕊６心皮,上部彼此分离、下部联合。倒生胚珠,双珠被,厚球心。胚囊发育蓼型。成熟胚囊为七细胞结构,但两个助细胞退化较早。     

HETEROCHRONIC DEVELOPMENTAL PLASTICITY IN LARVAL SEA URCHINS AND ITS IMPLICATIONS FOR EVOLUTION OF NONFEEDING LARVAE

Preexisting developmental plasticity in feeding larvae may contribute to the evolutionary transition from development with a feeding larva to nonfeeding larval development. Differences in timing of development of larval and juvenile structures (heterochronic shifts) and differences in the size of the larval body (shifts in allocation) were produced in sea urchin larvae exposed to different amounts of food in the laboratory and in the field. The changes in larval form in response to food appear to be adaptive, with increased allocation of growth to the larval apparatus for catching food when food is scarce and earlier allocation to juvenile structures when food is abundant. This phenotypic plasticity among full siblings is similar in direction to the heterochronic evolutionary changes in species that have greater nutrient reserves within the ova and do not depend on particulate planktonic food. This similarity suggests that developmental plasticity that is adaptive for feeding larvae also contributes to correlated and adaptive evolutionary changes in the transition to nonfeeding larval development. If endogenous food supplies have the same effect on morphogenesis as exogenous food supplies, then changes in genes that act during oogenesis to affect nutrient stores may be sufficient to produce correlated adaptive changes in larval development.     

CAENOGENESIS,DEVELOPMENTAL VARIABILITY,AND EVOLUTION IN THE CARPUS AND TARSUS OF THE MARBLED NEWT TRITURUS MARMORATUS

In this paper, after a comparative analysis of the development of Triturus marmoratus, we explore the existence of caenogenetic events and their ontogenetic and phylogenetic consequences. The adult morphology of the Triturus marmoratus limb, in terms of number and spatial arrangement of skeletal elements, agrees with the general pattern of urodeles. The congruence in the typical pattern of adult morphology does not hint at the striking differences in embryonic development. These differences can be summarized as follows: 1) Presence of a “central axis” that develops in a distal-to-proximal direction. It originates in the basale commune giving rise to the centrale and the intermedium. Thus, there is no postaxial branching as found in Ambystoma mexicanum. 2) Again, unlike in Ambystoma mexicanum, we find a postaxial structure composed of the ulnare (fibulare)-distal carpal (tarsal) 4-metacarpal (metatarsal) 4 which is independent of the “digital arch.” 3) The (forelimb) digits, in particular, digits 1, 2, and 3, undergo disproportionate elongation. For example, the second digit, composed of a thin continuous, cartilaginous rod, becomes longer than the rest of the limb. Our study of the patterns of embryonic connectivity suggests the coexistence of three directions of growth and morphogenesis in the development of the Triturus marmoratus limb. 1) A proximo-distal one that gives rise to the preaxial axis, “primary axis,” and individual digits. 2) An anterio-posterior axis of development that gives rise to the “digital arch” and determines the number of digits. 3) A disto-proximal central axis that originates in the basale commune and sequentially generates the centrale and the intermedium. We speculate that heterochronic interspecific variation in the time of onset of limb bud formation is related to the degree of precocious digital elongation. Selection for long extremities in early larval stages, associated with functional demands for locomotion and balancing, may be the cause for the above listed changes in developmental pattern. Thus, the reported system is an example of how selection during ontogeny can result in the evolution of the developmental process.     

科尔沁沙地69种植物种子重量比较研究

 研究了科尔沁沙地69种植物的繁殖体（30种为种子,39种为果实）重量。结果表明：1）传播体为果实的植物可分为4个组别（即果实单粒重<0.1 mg、0.1～0.999 9 mg、1～9.999 9 mg、10～99.999 9 mg）;黄蒿（Artemisia scoparia）果实(0.051 7 mg)和小香蒲（Typha minima）果实(0.068 2 mg)最轻,苍耳（Xanthium sibiricum）单个果实（77.894 3 mg）最重;2）传播体为种子的植物可分为3个组别（即种子单粒重0.1～0.999 9 mg、1～9.999 9 mg、10～99.999 9 mg）;马齿苋（Portulaca oleracea）种子（0.151 4 mg）最轻,苦参（Sophora flavescens）种子(46.781 6 mg)最重;3）黄蒿、马齿苋、轮叶沙参（Adenophora tetraphylla）、碱地肤（Kochia sieversiana）、狼尾花（Lysimachia barystachys）、灰绿藜（Chenopodium glaucum）、刺沙蓬（Salsola ruthenica）、菟丝子（Cuscuta chinensis）、大籽蒿（Artemisia sieversiana）、狗尾草（Setaria viridis）、野古草（Arundinella hirta）等植物所以广泛分布可能是因为它们繁殖体轻（<1 mg）且具有持久土壤种子库;4）流沙上的先锋植物或沙生演替系列前期植物沙蓬（Agriphyllum squarrosum）、差巴嘎蒿（Artemisia halodendron）、乌丹蒿（Artemisia wudanica）、狗尾草、雾冰藜（Bassia dasyphylla）的繁殖体要么重量居中或偏大,要么有降低位移的其它机制。     

华西南干热河谷种子植物区系的特征,性质和起源

华西南干热河谷种子植物的区系特征表现为其植物科、属、种各级分布区类型的多样性,明显的特有现象和丰富的标志种。根据本地区的区系成分分析,可以得出以下有关区系性质和起源的结论：（１）总体上看干热河谷种子植物区系属于亚热带性质;（２）本地区一些半稀树草原和马基状灌丛的区系成分类似于热带非洲、热带亚洲和地中海地区相同植被的成分;（３）许多植物料和属为古热带成分,起源于古南大陆;（４）少数残遗种或其后裔可追     

秦岭种子植物区系科的组成、特点及其地理成分研究

秦岭种子植物区系组成丰富, 共有种子植物198 科、1007 属、3446 种, 区系组成的大科及主要科共16 科, 占秦岭种子植物总数属的50.05%, 总种数的57.25%, 它们构成了秦岭植物区系组成的基本框架, 就其性质来讲, 绝大多数为温带性质。松科、壳斗科、桦木科、杨柳科、蔷薇科、杜鹃花科、禾本科、莎草科等是秦岭植被的区系组成的优势科, 从地理成分上来分析, 本区科的分布型可以划分为世界或亚世界分布科、热带分布科、温带分布科、间断分布科以及东亚和中国特有科, 其区系的起源则有明显的古老性。     

MATERNAL INHERITANCE AND ITS EFFECT ON ADAPTIVE EVOLUTION: A QUANTITATIVE GENETIC ANALYSIS OF MATERNAL EFFECTS IN A NATURAL PLANT POPULATION

A mother can influence a trait in her offspring both by the genes she transmits (Mendelian inheritance) and by maternal attributes that directly affect that trait in her offspring (maternal inheritance). Maternal inheritance can alter the direction, rate, and duration of adaptive evolution from standard Mendelian models and its impact on adaptive evolution is virtually unexplored in natural populations. In a hierarchical quantitative genetic analysis to determine the magnitude and structure of maternal inheritance in the winter annual plant, Collinsia verna, I consider three potential models of inheritance. These range from a standard Mendelian model estimating only direct (i.e., Mendelian) additive and environmental variance components to a maternal inheritance model estimating six additive and environmental variance components: direct additive and environmental variances; maternal additive and environmental variances; and the direct-maternal additive () and environmental covariances. The structure of maternal inheritance differs among the 10 traits considered at four stages in the life cycle. Early in the life cycle, seed weight and embryo weight display substantial , a negative , and a positive . Subsequently, cotyledon diameter displays and of roughly the same magnitude and negative . For fall rosettes, leaf number and length are best described by a Mendelian model. In the spring, leaf length displays maternal inheritance with significant and and a negative . All maternally inherited traits show significant negative . Predicted response to selection under maternal inheritance depends on and as well as . Negative results in predicted responses in the opposite direction to selection for seed weight and embryo weight and predicted responses near zero for all subsequent maternally inherited traits. Maternal inheritance persists through the life cycle of this annual plant for a number of size-related traits and will alter the direction and rate of evolutionary response in this population.     

TESTING MODELS OF SEX RATIO EVOLUTION IN A GYNODIOECIOUS PLANT: FEMALE FREQUENCY COVARIES WITH THE COST OF MALE FERTILITY RESTORATION

In many gynodioecious species, cytoplasmic male sterility genes (CMS) and nuclear male fertility restorers (Rf) jointly determine whether a plant is female or hermaphrodite. Equilibrium models of cytonuclear gynodioecy, which describe the effect of natural selection within populations on the sex ratio, predict that the frequency of females in a population will primarily depend on the cost of male fertility restoration, a negative pleiotropic effect of Rf alleles on hermaphrodite fitness. Specifically, when the cost of restoration is higher, the frequency of females at equilibrium is predicted to be higher. To test this prediction, we estimated variation in the cost of restoration across 26 populations of Lobelia siphilitica, a species in which Rf alleles can have negative pleiotropic effects on pollen viability. We found that L. siphilitica populations with many females were more likely to contain hermaphrodites with low pollen viability. This is consistent with the prediction that the cost of restoration is a key determinant of variation in female frequency. Our results suggest that equilibrium models can explain variation in sex ratio among natural populations of gynodioecious species.     

EVOLUTION OF FLORAL TRAITS IN A HERMAPHRODITIC PLANT: FIELD MEASUREMENTS OF HERITABILITIES AND GENETIC CORRELATIONS

Genetic variances, heritabilities, and genetic correlations of floral traits were measured in the monocarpic perennial Ipomopsis aggregata (Polemoniaceae). A paternal half-sib design was employed to generate seeds in each of four years, and seeds were planted back in the field near the parental site. The progeny were followed for up to eight years to estimate quantitative genetic parameters subject to natural levels of environmental variation over the entire life cycle. Narrow-sense heritabilities of 0.2–0.8 were detected for the morphometric traits of corolla length, corolla width, stigma position, and anther position. The proportion of time spent by the protandrous flowers in the pistillate phase (“proportion pistillate”) also exhibited detectable heritability of near 0.3. In contrast, heritability estimates for nectar reward traits were low and not significantly different from zero, due to high environmental variance between and within flowering years. The estimates of genetic parameters were combined with phenotypic selection gradients to predict evolutionary responses to selection mediated by the hummingbird pollinators. One trait, corolla width, showed the potential for a rapid response to ongoing selection through male function, as it experienced both direct selection, by influencing pollen export, and relatively high heritability. Predicted responses were lower for proportion pistillate and corolla length, even though these traits also experienced direct selection. Stigma position was expected to respond positively to indirect selection of proportion pistillate but negatively to selection of corolla length, with the net effect sensitive to variation in the selection estimates. Anther position also was not directly selected but could respond to indirect selection of genetically correlated traits.     

DEMOGRAPHIC GENETICS OF A PIONEER TROPICAL TREE SPECIES: PATCH DYNAMICS,SEED DISPERSAL,AND SEED BANKS

We consider whether changes in population-genetic structure through the life cycle of Cecropia obtusifolia, a tropical pioneer tree, reflect its gap-dependent demography and the role of evolutionary processes that are important for this species. We asked whether the spatial scale at which population-genetic subdivision occurs corresponds to the scale of habitat patchiness created by gap dynamics; whether patterns of seed dispersal and storage in the soil affect spatial genetic patterns; and whether spatial genetic patterns change through the species life cycle. We estimated Wright's F-statistics for six successive life-history stages for individuals grouped into subpopulations according to occurrence in natural gaps, physical proximity, or occurrence within large quadrats. For each life stage, F_ST-statistics were significantly higher when individuals were grouped by gaps, although concordant patterns across life stages for the three grouping methods were obtained. This supports the hypothesis that patchy recruitment in gaps or among-gap heterogeneity influences the species' genetic structure. F-statistics of seeds collected from females before dispersal (tree seeds), seed-rain seeds, soil seeds, seedlings, juveniles, and adults grouped by gaps, were, respectively: F_IT = 0.004, 0.160, 0.121, 0.091, –0.0002, –0.081; F_IS = –0.032, 0.124, 0.118, 0.029, –0.016, –0.083; and F_ST = 0.035, 0.041, 0.003, 0.063, 0.015, 0.002. Spatial genetic differentiation in rain seeds was not significantly lower than that of tree seeds. The loss of genetic structure in the soil seed bank, relative to that found in the seed rain may be due to sampling artifacts, but alternative explanations, such as microsite selection or temporal Wahlund effect are also discussed. If structure among soil seeds is unbiased, the peak in seedling F_ST may be due to microsite selection. F_IS of seeds in the rain and soil were significantly greater than zero. A Wahlund effect is the most likely cause of these positive F_IS values. Such fine-scale substructuring could be caused by correlated seed deposition by frugivores. The decrease in F_IS from seedlings to adults could result from loss of fine-scale genetic structure during stand thinning or from selection.     

柠檬酸,葡萄糖和有机质对植物磷素吸收和土壤磷素形态的影响

研究了柠檬酸、葡萄糖和有机质（栎树类凋落物和三叶草茎叶）对几种栽培和野生植物磷素吸收以及高度风化老成土中磷素形态的影响。在未加入无机磷的情况下,连续加入柠檬酸溶液增加了温室盆栽大豆（Ｇｌｙｃｉｎｅｍａｘ（Ｌ．）Ｍｅｒｒ．）和高粱（Ｓｏｒｐｈｕｍｂｉｃｏｌｏｒ）对磷素的吸收。这表明,柠檬酸可以溶解土壤中被铁、铝氧化物固定的磷。当无机磷和柠檬酸溶液同时加入后。由于有机配位体能够阻止土壤对磷素的吸附和固定,植物对磷的吸收总量明显高于仅仅加入无机磷的对照。不论是否加入无机磷,葡萄糖均没有增加植物对磷素的吸收,但却改变了土壤中磷素的形态。该试验的结果还表明,Ｈｅｄｌｄｙ等人提出的土壤磷素分级方法不适于有机质含量很低的酸性土壤。在另一种性质极为相似的酸性土壤中施入粉碎的栎树（Ｑｕｅｒｃｕｓｓｐｐ．）凋落物和三叶草（ＴｒｉｆｏｌｉｕｍＰｒａｔｅｎｓｅ）后,野生商陆（Ｐｈｙｔｏｌａｃｃａａｍｅｒｉｃａｎａ）吸收磷素的能力增强。通过进一步对土壤中的磷素进行化学分级,结果表明,这些有机物质可以改变土壤中磷素存在的形态。本文还就有机质分解过程中的中间产物对土壤磷素有效性的影响机理进行了探讨。     

FEMALE CONTROL OF SPERM TRANSFER AND INTRASPECIFIC VARIATION IN SPERM PRECEDENCE: ANTECEDENTS TO THE EVOLUTION OF A COURTSHIP FOOD GIFT

Manipulation of ejaculates is believed to be an important avenue of female choice throughout the animal kingdom, but evidence of its importance to sexual selection remains scarce. In crickets, such manipulation is manifest in the premature removal of the externally attached spermatophore, which may afford females an important means of postcopulatory mate choice. We tested the hypothesis that premature spermatophore removal contributes significantly to intraspecific variation in sperm precedence by (1) experimentally manipulating spermatophore attachment durations of competing male Gryllodes sigillatus and (2) employing protein electrophoresis to determine the paternity of doubly mated females. The relative spermatophore attachment durations of competing males had a significant influence on male paternity, but the pattern of sperm precedence deviated significantly from the predictions of an ideal lottery. Instead, paternity data and morphological evidence accorded best with a model of partial sperm displacement derived here. Our model is similar to a displacement model of Parker et al. in that sperm of the second male mixes instantaneously with that of the first throughout the displacement process, but the novel feature of our model is that the number of sperm displaced is only a fraction of the number of sperm transferred by the second male. Regardless of the underlying mechanism, female G. sigillatus can clearly alter the paternity of their offspring through their spermatophore-removal behavior, and employ such cryptic choice in favoring larger males and those providing larger courtship food gifts. We discuss how female control of sperm transfer and intraspecific variation in sperm precedence may be important precursors to the evolution of gift giving in insects.     

VIOLATION OF DOLLO'S LAW: EVIDENCE OF MUSCLE REVERSIONS IN PRIMATE PHYLOGENY AND THEIR IMPLICATIONS FOR THE UNDERSTANDING OF THE ONTOGENY,EVOLUTION, AND ANATOMICAL VARIATIONS OF MODERN HUMANS

According to Dollo's law, once a complex structure is lost it is unlikely to be reacquired. In this article, we report new data obtained from our myology‐based cladistic analyses of primate phylogeny, which provide evidence of anatomical reversions violating Dollo's law: of the 220 character state changes unambiguously optimized in the most parsimonious primate tree, 28 (13%) are evolutionary reversions, and of these 28 reversions six (21%) occurred in the nodes that lead to the origin of modern humans; nine (32%) violate Dollo's law. In some of these nine cases, the structures that were lost in adults of the last common ancestor and are absent in adults of most subgroups of a clade are actually present in early ontogenetic stages of karyotypically normal individuals as well as in later ontogenetic stages of karyotypically abnormal members of those subgroups. Violations of Dollo's law may thus result from the maintenance of ancestral developmental pathways during long periods of trait absence preceding the reacquisition of the trait through paedomorphic events. For instance, the presence of contrahentes and intermetacarpales in adult chimpanzees is likely due to a prolonged/delayed development of the hand musculature, that is, in this case chimpanzees are more neotenic than modern humans.     

THE RELATIVE IMPORTANCE OF INBREEDING AND MATERNAL SEX IN DETERMINING PROGENY FITNESS IN SIDALCEA OREGANA SSP. SPICATA,A GYNODIOECIOUS PLANT

Gynodioecious plant populations contain both hermaphrodite and female individuals. For females to be maintained they must compensate for their loss of reproductive fitness through pollen. Females may achieve compensation by producing more and/or higher quality seeds than hermaphrodites. In this study, I investigated the independent and interactive effects of maternal sexual identity and inbreeding level on fitness of the progeny of hermaphrodites and females of Sidalcea oregana ssp.spicata. Seeds produced by selling hermaphrodites and by outcrossing or sib-crossing hermaphrodites and females, were planted in the field and greenhouse. Maternal-sex effects were substantial at the juvenile stages of the life cycle; seeds of females germinated in higher proportions and produced seedlings that grew significantly faster. Inbreeding effects were manifested primarily at the adult stage of the life cycle. Outcrossed plants were significantly larger and produced more flowers per plant than sib-crossed and selfed plants growing in the greenhouse. Progeny of hermaphrodites and females appeared to respond similarly to sib-matings. The maternal-sex effects observed in Sidalcea may have been related to cytoplasmically inherited factors and could be a driving force in the maintenance of females. Inbreeding depression could play a role in determining the fitness of both sex morphs, if females experience biparental inbreeding in the field. Frequent inbreeding of hermaphrodites may not be necessary to explain the maintenance of gynodioecy in this species.     

THE EVOLUTION OF DIAPAUSE IN THE KILLIFISH FAMILY RIVULIDAE (ATHERINOMORPHA,CYPRINODONTIFORMES): A MOLECULAR PHYLOGENETIC AND BIOGEOGRAPHIC PERSPECTIVE

Phylogenetic relationships within the family Rivulidae (order Cyprinodontiformes) are investigated using 1972 aligned base pairs of mitochondrial DNA (mtDNA) for samples representing 66 species. Genes analyzed include those encoding the 12S ribosomal RNA; transfer RNAs for valine, glutamine, methionine, tryptophan, alanine, asparagine, cysteine, and tyrosine; complete NADH dehydrogenase subunit II; and part of cytochrome oxidase I. Parsimony analysis of the aligned mtDNA sequences results in a single most parsimonious tree. The phylogeny reveals two independent origins of developmental diapause within the family Rivulidae. It is unlikely that diapause evolved de novo in each group, suggesting that the presence or absence of diapause is the result of developmental switches between alternative stabilized pathways. Phylogeny of the family Rivulidae shows high concordance with predictions derived from the geological history of South America and Central America. Basal lineages in the rivulid phylogeny are distributed primarily on geologically old areas, whereas more nested lineages occur in geologically younger areas. However, there is little concordance between the molecular phylogeny and currently available morphological hypotheses and existing taxonomies. Based on the mtDNA phylogeny, the genera Pterolebias, Rivulus, Pituna, and Plesiolebias are considered nonmonophyletic and warrant taxonomic reassessment.     

皇甫川流域柠条林地水分动态模拟——坡度、坡向、植被密度与土壤水分的关系

在皇甫川流域,随着林草覆盖度的增加,植被与水的矛盾日益突出,其中一个重要的问题就是植被密度与土壤水分之间的矛盾。土壤水分的降低影响了植被的生长,甚至导致了部分植被的死亡,因此对土壤水分与植被密度之间的关系进行研究非常重要,有助于合理造林密度的确定。在已有研究及实验观测的基础上,建立了柠条(Caragana intermedia)林地土壤水分动态模拟模型,模型考虑了主要的土壤、植物过程,包括土壤性状、降雨入渗、植物蒸腾、地表蒸发等;模拟了从1971至2000年,30年里各种立地条件(不同盖度、坡向和坡度)下的柠条林地土壤水分、蒸腾和蒸发等的日动态过程。通过比较不同立地条件下的土壤水分动态,研究了皇甫川流域典型柠条林地土壤水分与植被盖度、坡向和坡度之间的关系,并得出了它们之间的关系式。由得到的平地上柠条的适宜密度,同时结合上述关系式,得出了不同坡度、坡向的适宜密度。坡度小于10°时,适宜造林密度对坡度反应敏感,在10°~30°时,适宜盖度对坡度反应不敏感。对于小于10°的坡地,植被建设时要特别注意设计合理的植被密度。     

ALTERNATIVE MATING STRATEGIES AND THE EVOLUTION OF SEXUAL SIZE DIMORPHISM IN THE SIDE-BLOTCHED LIZARD, UTA STANSBURIANA: A POPULATION-LEVEL COMPARATIVE ANALYSIS

Population-level comparative analyses can link microevolutionary processes within populations to macroevolutionary patterns of diversification. We used the comparative method to study the evolution of sexual size dimorphism (SSD) among populations of side-blotched lizards ( Uta stansburiana ) . Uta stansburiana is polymorphic for different male mating and female life-history strategies in some populations, but monomorphic in others. We tested whether intrasexual selection among males, fecundity selection on females, and the presence of polymorphic strategies affected levels of SSD. We first resolved a phylogeny for 41 populations across the range of the species and documented a substantial regional structure. Our intraspecific data had significant phylogenetic signal, and correcting for phylogeny using independent contrasts had large effects on our results. Polymorphic populations had male-biased SSD and changes in male body size, levels of tail breaks, and SSD consistent with the intrasexual selection hypothesis. Monomorphic populations had changes in female size, clutch size, and SSD consistent with the fecundity selection hypothesis. Fecundity selection is a likely cause of some monomorphic populations having no SSD or female-biased SSD. Our results suggest that changes in mating strategies are associated with phenotypic diversification and multiple evolutionary forces can shape SSD.     

A TRYPSIN‐LIKE PROTEINASE IN THE MIDGUT OF Ectomyelois ceratoniae ZELLER (LEPIDOPTERA: PYRALIDAE): PURIFICATION,CHARACTERIZATION, AND HOST PLANT INHIBITORS

A trypsin‐like proteinase was purified and characterized in the midgut of Ectomyelois ceratoniae. A purification process that used Sepharyl G‐100 and DEAE‐cellulose fast flow chromatographies revealed a proteinase with specific activity of 66.7 μmol/min/mg protein, recovery of 27.04 and purification fold of 23.35. Molecular weight of the purified protein was found to be 35.8 kDa. Optimal pH and temperature were obtained 9 and 20°C for the purified trypsin proteinase, respectively. The purified enzyme was significantly inhibited by PMSF, TLCK, and SBTI as specific inhibitors of trypsins in which TLCK showed the highest inhibitory effect. Trypsin proteinase inhibitors were extracted from four varieties of pomegranate including Brait, Torsh‐Sabz, May‐Khosh, and Shirin by ion exchange chromatography. It was found that fractions 17–20 of Brait; fractions 18 and 21–26 of Torsh‐Sabz; fractions 1–7, 11–17, and 19–21 of May‐Khosh and fraction 8 for Shirin showed presence of trypsin inhibitor in these host. Comparison of their inhibitory effects on the purified trypsin proteinase of E. ceratoniae demonstrated that fractions from May‐khosh variety had the highest effect on the enzyme among other extracted fractions. Characterization of serine proteinases of insects mainly trypsins is one of the promising methods to decrease population and damages via extracting their inhibitors and providing resistant varieties.     

POPULATION STRUCTURE ALONG A STEEP ENVIRONMENTAL GRADIENT: CONSEQUENCES OF FLOWERING TIME AND HABITAT VARIATION IN THE SNOW BUTTERCUP,RANUNCULUS ADONEUS

Few studies have determined how gene flow and selection interact to generate population genetic structure in heterogeneous environments. One way to identify the potential role played by natural selection is to compare patterns of spatial genetic structure between different life cycle stages and among microenvironments. We examined patterns of spatial structure in a population of the snow buttercup (Ranunculus adoneus), using both adult plants and newly emerged seedlings. The study population spans a steep environmental gradient caused by gradual melting of snow within a permanent snowbed. Early-melting sites are characterized by denser vegetation, more fertile soils, and a longer growing season than late-melting sites tens of meters away. The flowering time of R. adoneus is controlled entirely by time of snowmelt, so the contiguous population is phenologically substructured into a series of successively flowering cohorts, reducing the opportunity for direct pollen transfer between early- and late-melting sites. For four highly polymorphic enzyme loci in this tetraploid species, there was subtle, but statistically significant, genetic differentiation between early, middle, and late-melting cohorts; adults usually showed greater differentiation among snowmelt zones than did seedlings. At two loci in adults and one locus in seedlings, homozygotes were more common than predicted at Hardy-Weinberg equilibrium, even when assuming maximum levels of double reduction during meiosis. This pattern suggests the occurrence of self-fertilization and/or population substructure. To determine how spatial isolation and phenological separation each contribute to genetic substructure, we used bivariate regression models to predict the numbers of allele differences between randomly paired individuals as a function of meters separation in space and days separation in flowering time. For newly emerged seedlings, we found that spatial separation was positively associated with genetic difference, but that the additional contribution of phenological separation to genetic difference was not significant. This implies that seeds and/or pollen move effectively across the snowmelt gradient, despite differences in flowering time. As was true for seedlings, spatial separation between paired adults contributed to greater genetic difference, but for a given spatial separation, the genetic difference between adult plants was reduced by phenological separation. This result implies that postemergence selection is favoring at least some seeds that migrate across the snowmelt gradient. Directional gene flow across the snowmelt gradient probably results from a genetic source-sink interaction, that is, the colonization of ecologically marginal late-melting sites by high quality seeds produced by the larger subpopulation in early-melting sites. Effective gene flow from high to low quality microenvironments is likely to impede adaptation to late-melting locations.