共查询到20条相似文献,搜索用时 343 毫秒
1.
干旱区人工植被恢复驱动的土地利用变化强烈影响了地表和土栖的节肢动物群落结构及多样性。然而,我们对地表节肢动物群落关键类群-蜘蛛和甲虫对固沙植被恢复的响应及与环境变化关系的认识还很有限。以天然固沙灌木林和2种人工固沙灌木林为研究对象,运用方差分析和多变量分析等方法定量研究了干旱区天然和人工固沙植被区地表蜘蛛和甲虫分布特征及影响要素。结果表明,天然灌木林与人工梭梭、柽柳林地表蜘蛛和甲虫群落组成明显不同,人工梭梭、柽柳林地表蜘蛛活动密度和甲虫多样性均显著高于天然灌木林,而地表甲虫密度和蜘蛛多样性变化与之相反。两种人工固沙灌木林之间蜘蛛和甲虫群落组成也存在一定差异,人工柽柳林地表蜘蛛活动密度、多样性和甲虫物种丰富度均显著高于人工梭梭林。进一步分析发现,蜘蛛群落中狼蛛科、平腹蛛科、皿蛛亚科和球蛛科与甲虫群落中拟步甲科、步甲科和象甲科等一些甲虫种属对3种生境的选择模式不同决定了蜘蛛和甲虫群落聚集结构。植被、土壤环境因子与蜘蛛和甲虫pRDA和pCCA结果表明,草本生物量、凋落物量、土壤含砂量、电导率和灌木盖度是影响蜘蛛分布的主要环境因子,它们解释了82.1%的蜘蛛群落变异;灌木盖度、草本生物量、土壤pH和砂含量是影响甲虫群落分布的主要环境因子,它们解释了60.6%的甲虫群落变异。总之,人工固沙灌木恢复影响了植被和土壤环境,它们相互作用改变了荒漠-绿洲过渡区蜘蛛和甲虫等地表节肢动物的分布格局。 相似文献
2.
3.
4.
5.
6.
8.
2004年4—10月,在甘肃子午岭天然次生林区采用巴氏诱罐法采集土壤蜘蛛2 164头,隶属于19科43种。研究表明:辽东栎林(Quercus liaotungensis)、油松林(Pinus tabulaeformis)和杨树林(Populus davidiana)3种森林植被类型中土壤蜘蛛群落组成有明显的差异;不同生境蜘蛛群落的组成成分和多样性指数各异;从各生境中捕获的蜘蛛个体数量分析,皿蛛科、平腹蛛科和科狼蛛科的数量最多,优势类群的组成相似;各生境类型中蜘蛛功能集团的组成及多样性也有明显差异。同时,分析了影响蜘蛛群落组成和多样性的主要因子是生境的植被类型和生境异质性。 相似文献
9.
10.
11.
Jerry A. Coyne 《Evolution; international journal of organic evolution》1993,47(3):778-788
Matings between Drosophila simulans females and males of the sibling species D. mauritiana are of abnormally short duration. These rapid matings interrupt the transfer of sperm, leading to substantial reproductive isolation in interspecific as compared to intraspecific copulations. Genetic analysis of this behavior shows that it is influenced much more by the male than the female genotype, with genes from D. simulans being dominant. In males, shortened copulation is caused by interspecific divergence at a minimum of three loci, with one gene on each of the major chromosomes. This is an underestimate of the true number of loci affecting the trait, which could be much larger. The two autosomes have the largest effect, whereas that of the X chromosome is much smaller. The genetic architecture of copulation duration and the larger effect of male than female genotype suggest that females can detect and discriminate against differences in male genitalia. 相似文献
12.
13.
Comparative phylogenetic and phylogeographic analyses have revealed a pervasive midpeninsular divergence in the mitochondrial genealogies of numerous vertebrate taxa distributed on the Baja California Peninsula. In this study, we extend the investigation of regional vicariance in Baja California to an arthropod taxon by examining patterns of phylogenetic and morphological divergence in the spider genus Homalonychus (Araneae, Homalonychidae). We analyzed data from two mtDNA genes (16S rRNA and NADH dehydrogenase subunit (1) and a nuclear gene (28S rRNA) using maximum parsimony and Bayesian phylogenetic analyses, and also conducted geometric morphometric analyses employing landmark data on male and female genitalia. Genes and morphology both reveal a deep split across the Colorado River and Gulf of California, separating Homalonychus selenopoides on the east side of river from its congener Homalonychus theologus on the west side of the river, including the Baja California Peninsula. Along the north-south axis of the Baja Peninsula, an apparently more recent midpeninsular phylogenetic break is evident within H. theologus in the mitochondrial genome and in female genitalia. However, there is no measurable divergence between northern and southern populations in either nuclear DNA or male genitalia. We suggest that this discordance between datasets reflects either a difference in rates of evolution between male versus female systems, or that male-based nuclear gene flow is obscuring a phylogenetic split that is fixed in the female-based systems. Our findings provide additional support for a midpeninsular Baja divergence event, although the timing and geological evidence for such an event remain elusive. 相似文献
14.
15.
The Late Jurassic thrips Liassothrips crassipes (Martynov) is redescribed, and its taxonomic position discussed. It is shown that the male genitalia of Liassothrips are similar to the terebrantian type, while the female genitalia resemble the tubuliferan type. Therefore, the Liassothripidae shows the possible evolutionary pathway of tubuliferan thrips. Liassothrips is treated as the oldest known member of the suborder Tubulifera (previously known beginning from the Eocene), the ancestors of which belonged to the family Aeolothripidae (Terebrantia) rather than Thripidae. 相似文献
16.
The correlated evolution of genitalia between sexes has been demonstrated in many taxa. However, it remains unclear whether female rather than male genitalia can play a key role in the correlated evolution of male and female genitalia. We conducted an extensive cross‐population analysis of the divergence patterns of genital structures, weights of whole genital organs, and the bodies of both sexes, and male genital length in a group of xystodesmid millipedes showing diverse genital morphologies. We demonstrate that the correlated evolution of male and female genitalia toward exaggerated states has occurred in the millipedes, which have evolved novel traits in both males (forceps‐like gonopods) and females (retractable bellows). Enlargement and elongation of forceps‐like gonopods may be advantageous in sperm competition, whereas enlargement and elongation of the bellows may facilitate acceptance/rejection of insemination for ensuring the female's fitness. These male and female genital parts have affected the correlated evolution in the opposite sex, resulting in diversification and exaggeration of genital morphology. Our study suggests that evolutionary novel traits in not only males but also in females could play an important role in the correlated evolution of genitalia between the sexes. 相似文献
17.
MAXI POLIHRONAKIS 《Biological journal of the Linnean Society. Linnean Society of London》2009,96(1):135-149
It is generally accepted that genitalia are among the fastest evolving characters in insects and that selection on these structures may increase speciation rates in groups with polygamous mating systems. If selection is causing genitalic divergence between or among populations of a species, one prediction is that geographical structure of genitalic morphology would be in place before genetic structure of a rapidly evolving neutral marker. The current study tests this hypothesis in the geographically widespread scarab beetle Phyllophaga hirticula by evaluating whether standing variation in male and female genitalia is more or less geographically structured than a mitochondrial genetic marker. Geographical structure of mitochondrial (mt)DNA and male and female genitalic shape were analysed using analysis of variance, multivariate analysis of variance, Mantel tests, and tests of spatial autocorrelation. The results show that, although female genitalia are more geographically structured than mtDNA, male genitalia are not. This pattern suggests that selection on female genitalic variation may be causing divergence of these structures among populations. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 135–149. 相似文献
18.
Asymmetric female genitalia and other remarkable morphology in a new genus of cobweb spiders (Theridiidae, Araneae) from Madagascar 总被引:1,自引:0,他引:1
INGI AGNARSSON 《Biological journal of the Linnean Society. Linnean Society of London》2006,87(2):211-232
Symmetry is such a conspicuous feature of life that asymmetries draw our immediate attention. While not uncommon in bilateral organisms in general, asymmetry in spiders is rare. Here I report the first case of antisymmetry in external female genitalia in spiders, in the new genus Asygyna (Theridiidae: Araneae) from Madagascar. In the nearly 39 000 species of spiders described to date, the external structure of the female genitalia is symmetric. In entelegyne spiders paired external copulatory openings each lead to an internal copulatory duct, whose roughly symmetrical trajectories terminate in paired receptacles, the spermathecae. In Asygyna , here exemplified by two new species, A. huberi and A. coddingtoni , laterality is evident in the internal and external female genitalia. A single copulatory opening leads (either to the left or right depending on the individual) to a single copulatory duct with a distinctly asymmetric trajectory. The duct splits terminally shortly before entering the two spermathecae. The males are symmetric, but possibly only one palp can be used in copulation with each female. If adaptive, the selective forces behind this asymmetry are perplexing, as male access to females seems reduced. However, if males are plentiful, asymmetry may benefit the female by reducing insertion times and thus shortening copulation time, and by tightening her control over which males sire her offspring. Asygyna has a range of other bizarre sex-related morphologies, including prosomal pits and a well developed stridulatory mechanism in both sexes, a male proboscis, and simplified palps. A phylogenetic analysis, including 63 taxa and 242 morphological characters, places Asygyna in Pholcommatinae, sister to the enigmatic genus Carniella . © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 211–232. 相似文献
19.
20.
Motoharu Okamoto 《American journal of botany》1989,76(1):14-22
The inflorescence of Fagus is generally considered to be a determinate one, i.e., an axillary dichasium, in contrast to those of most genera in the family, which are indeterminate, dichasial, or simple catkins. To understand the relationship between the two types, ontogenetic development of the inflorescence of Fagus crenata was investigated. The early developmental stages are similar in both the male and the female inflorescences. At first, the inflorescence is oval-shaped, then a swelling forms at the distal side of it. Subsequently, another swelling forms at the proximal side. The more or less conspicuous residual part of the primary inflorescence axis remains between the two swellings. The inflorescence becomes heart-shaped and the first flower forms at the summit of each swelling. Subsequently, higher-ordered flowers form dichasially in the male inflorescence, and the cupule valves differentiate in the female one. This organogenetic manner suggests that the inflorescence of Fagus is an indeterminate one, consisting of two dichasia arranged alternately on the primary axis. The scale leaves surrounding the inflorescence were also given a new interpretation. They were considered to be stipules of the bracts, because sometimes they constitute a continuous structure, together with an inconspicuous swelling between them. A proliferous-type monstrous cupule was interpreted as supporting evidence for the hypothesis. 相似文献