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Most investigations of mate-choice have focused on the outcomes of mate-choice (i.e. which mates are chosen), and thus we generally know very little about how mates are chosen (i.e. how mates are found, assessed, and selected). Mate-choice by females has been shown to be dependent on the state of the female, with females being less selective when limited by time or energy. This result could be caused by changes in female mate-assessment or mate-selection behavior. We examined whether manipulations of time and energy affected the mate-choice behavior of female threespine stickleback ( Gasterosteus aculeatus ). We found that female mate-choice behavior, when not divided into stages, was affected by both of the manipulations. This matches previous findings. When we divided female courtship behavior into six stages, we found that the two manipulations affected different portions of the mate-choice process. The holding-time manipulation changed female behavior at the beginning and end of the mate-choice process and the swimming manipulation changed female behavior only at the end of the mate-choice process. Neither of the manipulations significantly affected female behavior in the middle portion of the mate-choice process. Thus, the mate-choice process appears to be composed of multiple state-dependent decisions. We discuss how a better mechanistic understanding of how female state affects female mate-choice behavior can produce testable predictions and provide a basis for investigating the evolution of mating systems.  相似文献   

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The influence of temperature on reproduction and movement was examined for seven geographic isolates of Bursaphelenchus xylophilus, three of B. mucronatus, and two of their interspecific hybrids. All nematode isolates tended to be more active and fecund the higher the temperature, with the isolates of B. xylophilus reaching a reproductive peak at higher temperatures than isolates of B. mucronatus. Most isolates of B. xylophilus and B. mucronatus did not produce significantly more progeny at higher male-to-female ratios. The interspecific hybrids appear to possess temperature-related characteristics of either B. xylophilus or both of the parents.  相似文献   

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The emphasis of this presentation is that social behavior isbasically involved in the curtailment of growth of laboratorypopulations of prairie deermice through inhibiting influenceson the reproductive development and function of population animals.Reproductive inhibition is not directly related to the numbersof animals present per se since physiological characteristicsare similar between animals from populations differing widelyin density under identical conditions of the physical environment.Thus, density should be interpreted relative to social or otherbehavioral factors and we should think of animals in a populationin a qualitative as well as a quantitative sense. Populationgrowth is controlled either by cessation of reproduction orby mortality of young and while 95% of the young remain reproductivelyimmature and fail to reproduce, the weights and characteristicsof their reproductive organs differ dependent upon the mechanismby which population growth is curtailed. Mechanisms of growthcurtailment thus develop intrinsically to each population andinvolve communication through one or more of the senses of touch,smell, sight, hearing or taste. My data suggest that tactilecues from population animals (not necessarily overt aggression)may be of major importance in producing the reproductive retardationobserved although chemosignals or other stimuli such as visualor auditory cues may act to slow reproductive recovery of inhibitedanimals. Data presented support the contention of a behavioral-physiologicalrelationship distinct for each population.  相似文献   

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Die männliche Balz einer amerikanischen Population des Dreistacheligen Stichlings wurde mit der der europäischen Variation verglichen. Die amerikanischen ♂ ♂ erreichen die Schwelle für die meisten sexuellen Verhaltensweisen viel langsamer; sie zeigen während der Balz mehr Nestaktivitäten und Stachelreizungen. Da es Anzeichen gibt, daß sie auch weit angriffslustiger sind, werden diese Handlungen (nach Wilz 1970 b) als bedeutsam für die Umstellung des ♂ auf sexuelles Verhalten aufgefaßt.  相似文献   

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SYNOPSIS. Data from the literature and from our own studieson the receptors for prolactin (PRL) and growth hormone (GH)are reviewed and analyzed. Receptors for PRL have been studiedin a wider range of species and in a greater diversity of targetorgans than have the binding sites for GH. Although GHs arestructurally more highly conserved among the vertebrates thanare PRLs, the available data indicate that there is greaterdiversity among GH receptors than there is among PRL receptors.In general, GH receptors show greater species specificity butless hormone specificity than do PRL receptors. The reason forthe greater diversity among GH receptors as compared to PRLreceptors is unknown; it bears no relationship to phylogeny. Data on the binding of purified preparations of mammalian PRL,GH and placental lactogen (PL) to renal and hepatic receptorsfor PRL and GH, respectively, of several vertebrate speciesare reviewed. The species and hormone specificity of the bindingof the hormones to the two typesof receptors showed no consistentpattern. To explain this disarray, we propose that the receptorbinding domains of PRL and GH were present in their common ancestralgene and that they havebeen retained to variable degrees byall of the descendant members of the PRL-GH family. We furtherpropose that hormone and species specificity of binding is determinedby hindering features on the hormones and on the receptors,rather than by merely the presence or absence of the appropriatebinding determinants.  相似文献   

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Study of interactions among fishes and benthic invertebrates off southern California's Santa Catalina Island showed the great extent to which taxa are defined by trophic relations. The dominant fishes there are acanthopterygian teleosts, with the serranine serranid Paralabrax clathratus morphologically nearest the evolutionary mainstream. Because mainstream species have morphologies similar to their progenitors, marine communities have a long history of adaptations to threats from generalized predators like P. clathratus. Species examined at Santa Catalina indicate this experience has produced four basic defenses: smallness, which presents difficulties for predators with large and simply constructed feeding mechanisms; dissemblance, as through camouflage, which makes detection by visual hunters difficult; inedibility, which is attained by incorporating materials that an unspecialized digestive system cannot accommodate; and nocturnality, which results in avoiding diurnal predators altogether. Examination of trophic relations among the major fishes in Santa Catalina communities shows each with specialized ways to counter these defenses. Prey smallness has been met by reducing size of mouth relative to size of prey, either by evolving as smaller fishes or through structural changes in head and jaws. Prey dissemblance has been accommodated through enhanced visual acuity and varied means to remain an unrecognized threat while waiting for prey to move. Inedibility has been countered by developing specialized features of the alimentary tract, including dentition, while adjustments to nocturnality have included enhanced sensory capabilities that detect prey in low light. These adaptations to prey defenses define varied lines of divergence from the teleost mainstream as represented atbreak Santa Catalina.  相似文献   

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Analysis of 1,063 stomach contents from 39 species of sea snakesindicates that about one-third of the shallow, warm, marine,Indo-Australian fish families are preyed upon by sea snakes.Families of eels and gobies are taken by the greatest numbersof snake species. Most species of sea snakes feed on fish familieswhose members are relatively sedentary, dwelling along the bottom,within burrows or reef crevices. With one exception, a fishegg-eating specialization found uniquely in the Aipysurus-Emydocephaluslineage, the dietary habits of sea snakes cannot be categorizedaccording to the snakes' three phylogenetic lineages. Eels,mullet-like, rabbitfish-like and goby-like fish forms are takenby all three lineages. Two or three snake species are generalists,and numerous ones specialize on eels, goby-like fish or catfish.There are differences among sea snake species in the relationshipbetween snake neck girth and the maximum diameter of the prey;in the relationships of both snake gape measurements and fanglength, to the type of prey taken; and in the relationship ofsnake shape and body proportions to the prey selected. Severalmodes of feeding have been observed among sea snakes: feedingin nooks and crannies in the bottom or in reefs, cruising nearthe bottom, and feeding in drift lines. Analysis of percentdigestion of stomach contents and projections backward to thetimes of prey capture provides evidence for feeding periodicity.The greatest amount of diet overlap is for two species of seasnakes which do not both occur at the same locality. Where speciesdo co-occur, diet overlap index values are lower. The numbersof species present as well as their relative abundances varyamong localities as does the relative importance of generalists,eel-eaters, egg-eaters and other specialized feeders.  相似文献   

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为比较荔枝(Litchi)和龙眼(Dimocarpus)与其属间杂种的茎、叶解剖结构,采用徒手切片法、组织离析法和石蜡切片法对茎、叶片结构进行观察比较。结果表明,‘杂种A’和‘杂种B’的髓率、树皮率均居于父母本之间,而木质部率、导管总面积/木质部面积的比值、导管分子内径则表现出显著的超亲优势;‘杂种C’和‘杂种D’的树皮率和射线宽度均小于父母本。‘杂种A’和‘杂种B’导管分子无尾和两端水平的频率居于父母本之间,‘杂种C’和‘杂种D’的导管分子形态特征较接近其母本‘石峡’,‘杂种D’的导管分子长度显著大于父母本。4个杂种的叶主脉厚均居于父母本之间,‘杂种D’的叶脉突起度和‘紫娘喜’的栅栏组织/海绵组织厚度比值均显著大于其他试材。4个属间杂种叶片表皮细胞的大小、垂周壁的形态均居于父母本之间;荔枝和龙眼叶片表皮特征差异明显,可以作为两属的鉴别特征。4个属间杂种的解剖结构总体上呈现出较明显的偏母遗传效应。  相似文献   

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The effects of dominant allele A r of locus Agoution the morphology of hair pigmentation were described in foxes. The A r allele was shown to determine the type of melanin and its content in hair with no effect on the morphology of pigment granules and their distribution throughout a hair. Using the method of electron spin resonance (ESR), the types of melanin (eumelanin and pheomelanin) and their content in the hair of red (A r A r EE) and silver (aaEE) foxes and their hybrids (A r aEE) were determined. In silver foxes, only one type of melanin (eumelanin) was found. In red foxes and their hybrids (which are phenotypically similar but darker than red foxes), both types of melanin (eu- and pheomelanin) were found. The highest melanin content was detected in the coat of silver foxes. In the hybrids, the total melanin content was lower than in silver foxes, but significantly higher than in red foxes. In red foxes, the contribution of pheomelanin to the total hair melanin content was twice as large as in the hybrids.  相似文献   

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Using inductively coupled plasma-mass spectrometry after samples microwave-assisted acid digestion, zinc (Zn), copper (Cu), and manganese (Mn) levels were measured in 14 different areas of the human brain of adult individuals (n?=?42; 71?±?12, range 50–101 years old) without a known history of neurodegenerative, neurological, or psychiatric disorder. The main goals of the work were to establish the “normal” (reference) values for those elements in the human brain and to evaluate the age-related changes, a prior and indispensable step in order to enlighten the role of trace element (TE) in human brain physiology and their involvement in aging and neurodegenerative processes. Considering the mean values for the 14 regions, Zn (mean ± sd; range 53?±?5; 43–61 μg/g) was found at higher levels, followed by Cu (22?±?5; 10–37 μg/g) and Mn (1.3?±?0.3; 0.5–2.7 μg/g). The TE distribution across the brain tissue showed to be quite heterogeneous: the highest levels of Zn were found in the hippocampus (70?±?10; 49–95 μg/g) and superior temporal gyrus (68?±?10; 44–88 μg/g) and the lowest in the pons (33?±?8; 19–51 μg/g); the highest levels of Cu and Mn were found in the putamen (36?±?13; 21–76 μg/g and 2.5?±?0.8; 0.7–4.5 μg/g, respectively) and the lowest in the medulla (11?±?6; 2–30 μg/g and 0.8?±?0.3; 0.2–1.8 μg/g, respectively). A tendency for an age-related increase in Zn and Mn levels was observed in most brain regions while Cu levels showed to be negatively correlated with age.  相似文献   

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When studying animal behavior, it is often necessary to examine traits as a package, rather than as isolated units. Evidence suggests that individuals behave in a consistent manner across different contexts or over time; that is, behavioral syndromes. We compared locomotor activity levels and mating success between beetles derived from two regimes artificially selected for the duration of death‐feigning behavior in the adzuki bean beetle, Callosobruchus chinensis. The two selection regimes comprised strains with higher (L) and lower (S) intensity (frequency and duration) of death‐feigning behavior, respectively. We found that S strains had higher activity levels than L strains for both sexes, i.e., there is a negative genetic correlation between death feigning and activity. In addition, we found that S strains had higher mating success than L strains, presumably due to higher activity, in males but not in females. We thus demonstrate that death feigning is genetically correlated to mating behavior in males but not females in this species, suggesting that behavioral correlations may not always reflect in the same way in both sexes.  相似文献   

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This review explores the field of fluorescent proteins (FPs) from the perspective of their marine origins and their applications in marine biotechnology and proteomics. FPs occur in hydrozoan, anthozoan, and copepodan species, and possibly in other metazoan niches as well. Many FPs exhibit unique photophysical and photochemical properties that are the source of exciting research opportunities and technological development. Wild-type FPs can be enhanced by mutagenetic modifications leading to variants with optimized fluorescence and new functionalities. Paradoxically, the benefits from ocean-derived FPs have been realized, first and foremost, for terrestrial organisms. In recent years, however, FPs have also made inroads into aquatic biosciences, primarily as genetically encoded fluorescent fusion tags for optical marking and tracking of proteins, organelles, and cells. Examples of FPs and applications summarized here testify to growing utilization of FP-based platform technologies in basic and applied biology of aquatic organisms. Hydra, sea squirt, zebrafish, striped bass, rainbow trout, salmonids, and various mussels are only a few of numerous instances where FPs have been used to address questions relevant to evolutionary and developmental research and aquaculture.  相似文献   

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疏花蔷薇与现代月季品种及其杂交后代的染色体核型分析   总被引:1,自引:0,他引:1  
以疏花蔷薇(Rosa laxa,2n=2x=14)和现代月季品种‘Kardinal’、‘Solidor’、‘Yuzen’(2n=4x=28)为亲本进行杂交,杂交组合疏花蔷薇בKardinal’、疏花蔷薇בSolidor’、‘Yuzen’×疏花蔷薇分别获得5株、5株和6株杂交后代。采用常规压片法,对亲本及杂交后代的染色体数目和核型进行了分析。结果显示:杂交后代中除疏花蔷薇בKardinal’组合有1株为二倍体外,其余15株均为三倍体;疏花蔷薇的核型为12m+2sm,属1A型;现代月季品种‘Kardinal’、‘Solidor’、‘Yuzen’的核型分别为28m、28m、24m(2SAT)+4sm,核型类型分别为1A、1B、2B型;疏花蔷薇בKardinal’组合的F1代包括1A、1B和2A等3种核型;疏花蔷薇בSolidor’组合的F1代包括1A和1B等2种核型;‘Yuzen’×疏花蔷薇组合的F1代包括1A、1B和2B等3种核型。根据染色体数目和形态分析结果确定,获得的三倍体后代为真杂种,但对于二倍体后代的杂种真实性不能做出判断。  相似文献   

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Early modern and archaic humans are associated with similar lithic industries in the Middle Paleolithic of the southern Levant, but new data suggest that they used the environment in different ways. Evidence from analyses of seasonally deposited increments of the teeth of the animals they hunted suggests that modern humans primarily practiced a strategy ofcirculating seasonal mobility, while archaic humans in the same region 30,000 years later were more residentially mobile. Analyses of their lithic hunting technology further suggest that archaic humans hunted more frequently than did modern humans. We argue that this greater hunting intensity may have been a strategy for coping with the consequences of resource biodepletion resulting from long-term, multiseasonal occupation of sites. These behavioral contrasts may be related to some of the morphological differences between early modern and archaic humans.  相似文献   

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