首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Species loss by habitat replacement operating as an ecological filter is a well‐known consequence of modern human activities. In contrast, the ecological and evolutionary response of species overcoming those filters in converted habitats has not been thoroughly explored. Species that persist are subject to novel and potentially stressful conditions that may induce certain morphological changes. We evaluated changes in the functional morphology of three anuran species persisting after the conversion of areas of the Atlantic Forest into pine plantations. We specifically evaluated differences in body size and body condition indices, head width, and hind legs’ length between adult individuals from both habitats and sexes. Habitat conversion and sexual dimorphism affected the morphology of the three anurans, with varying effects upon species and traits. Regarding the effect of habitat conversion, Elachistocleis bicolor increased body condition in plantations with no changes in the other traits, Physalaemus cuvieri showed only a marginal increment in residual body mass in plantations, and Odontophrynus americanus exhibited a substantial increment in body size while maintaining its body condition in plantations. Remarkably, none of the results suggested these persistent anurans were stressed by forest conversion. This study shows that habitat conversion may induce intraspecific morphological changes in ecologically relevant traits of persistent species, and that disturbed areas do not necessarily imply stressful, low quality habitats affecting all persistent native species negatively.  相似文献   

2.
Wild populations are continuously subjected to changes in environmental factors that pose different challenges. Body condition and hormones have been commonly used as health indicators due to their potential correlation with fitness. In the present study, we analyzed whether habitats of different quality influenced body mass, food intake and physiological stress levels in wild wood mice (Apodemus sylvaticus). Field work was seasonally carried out in Holm oak woods and pine forests in central Spain. A total of 93 wood mice from 4 different populations (2 per habitat type) were live‐trapped. From each captured individual we noted body mass and food intake, measured as the amount of bait remaining in each trap. The physiological stress levels were measured non‐invasively in collected fresh feces by quantifying fecal corticosterone metabolites (FCM) with a 5a‐pregnane‐3ß,11ß, 21‐triol‐20‐one enzyme immunoassay. Wood mice abundances decreased from spring to summer, were higher in Holm oak woods than in pine forests and also resulted in different age‐class distribution between both habitats. Individuals inhabiting pine forests showed a lower body mass and increased food intake, probably because of the comparatively lower food quality and availability in this habitat. Furthermore, these individuals showed increased physiological stress levels, likely due to the lower quality habitat in relation to both food and vegetation cover availability. Overall, besides affecting local wood mouse abundance, our study underscores the effect of habitat quality on body mass, food intake and the endocrine stress response. Considering the wood mouse's pivotal position in ecosystems, these results could help in the understanding of environmental traits hampering the viability of wild populations.  相似文献   

3.
The thermoregulation of the largest subterranean rodent, genus Bathyergus, comprising two species, B. suillus and B. janetta, occurring in mesic and semiarid habitats respectively, was investigated and compared with that of other subterranean rodents. Both species display low resting metabolic rates and low body temperatures characteristic of subterranean rodents. The lower metabolism and smaller body size of B. janetta, may be an ‘energy-saving’ adaptation to its semi-arid habitat.  相似文献   

4.
Attachment, a normal behavior among social animals, is quite significant since owners worry about their pets and take care of them because of this affective connection. There are not enough research studies that focus on attachment between owners and their cats. The general objective of this study was to identify attachment behaviors, directed toward their owners, in cats of different body types, age groups, and sexes in an experimental situation.Twenty-eight cats, ranging from 1 to 7 years of age and having different body types, were used in the study without taking into account sex or reproductive status. These cats underwent an Ainsworth’s Adapted Strange Situation Test. Event frequencies and behavioral state durations in individual type behaviors such as exploration/locomotion, alertness, and inactivity were registered using direct focal sampling. For data analysis, cats were divided by body type, sex, and reproductive status. Analysis of variance (ANOVA) of locomotion/exploration revealed a statistically significant difference (N = 28, F = 13.55, P < 0.001) between the episodes with the owner, alone, and with a stranger with cats spending more time engaged in locomotion/exploration while accompanied by their owner. On the alert behavior event frequency, difference (ANOVA, F = 7.44, P < 0.05) was found, which showed a higher frequency while in the company of a stranger. Last, in the inactivity time ratio, a significant difference was found (ANOVA, F = 18.55, P < 0.001), where the time spent on this behavior was considerably higher when the animal was alone.These results are consistent with the ones obtained by Ainsworth in children attached to their mothers; therefore, it can be said that cats can manifest attachment behaviors toward their owners. Further studies are indicated to see whether cats can develop separation anxiety.  相似文献   

5.
对甘肃省天祝藏族自治县抓喜秀龙乡境内不同生境条件下（阶地、阴坡、山脊、阳坡）高寒草甸草原生长季中期、末期的草地植被状况进行调查究,并进行生物多样性评价,旨在探寻生境因子对草地生产力的影响,为不同生境草地合理利用提供依据。结果表明：相同生境下草地植被在生长季中期和末期物种数量差异不显著,但其群落结构差异显著。植被盖度为阳坡<山脊<阶地<阴坡,阶地与阴坡盖度均显著高于阳坡（P<0.05）,7月底山脊盖度与阴坡差异显著（P<0.05）;地上生物量为山脊<阳坡<阶地<阴坡,其中样地间除9月初山脊与阳坡生物量差异不显著外,其余均差异显著（P<0.05）。同一时期不同生境条件下植被物种数目、群落物种丰富度Margelef指数、物种多样性Shannon-Wiener指数均为阶地<阳坡<山脊<阴坡,各生境间群落均匀度Pielou指数变化规律不明显,可能不适用于高寒草地的评价。植被群落相似性系数差异变化表明生境对草地群落组成结构的影响显著。  相似文献   

6.
Genetic polymorphisms in genes related to neurotransmitters or hormones affect personality or behavioral traits in many animal species including humans. In domestic animals, the allele frequency of such genes has been reported to be different among breeds and it may account for breed differences in behavior. In this study, we investigated breed differences in horses in the dopamine receptor D4 gene (DRD4), which has been reported to affect horse personality. We collected samples from seven horse breeds including those native to Japan and Korea, and compared the sequence of the DRD4 exon3 region among these breeds. We found that there were two types of polymorphisms (VNTR and SNPs) in the exon3 region, and some of them seemed to be breed-specific. In addition, we found that the allele frequency of G292A, reported to be associated with horse personality, differed greatly between native Japanese horses and Thoroughbred horses. The frequency of the A allele which is associated with low curiosity and high vigilance, was much lower in native Japanese horses (Hokkaido, 0.03; Taishu, 0.08) than in Thoroughbreds (0.62). This difference may account for breed differences in personality or behavioral traits. Further studies of the function of these polymorphisms and their effect on behavior are indicated.  相似文献   

7.
Gene flow among populations in different selective environments should favor the evolution of phenotypic plasticity over local adaptation. Plasticity in development is a common response to long‐term hypoxia in some widespread African fishes, including Pseudocrenilabrus multicolor, a cichlid that exploits both normoxic (high oxygen) rivers/lakes and hypoxic (low oxygen) swamps. Previous studies have shown that fish from normoxic and hypoxic sites differ in many traits, including gill size, brain size and body shape, and that much of this variation reflects developmental plasticity. However, these earlier studies focused on areas in Uganda where gene flow between swamp and river or lake populations is high. In this study we tested the hypothesis that P. multicolor from a relatively isolated lake population (Lake Saka, Uganda) exhibit low levels of plasticity in traits related to oxygen uptake. Multiple broods of P. multicolor from Lake Saka were reared under low and high dissolved oxygen, and traits related to gill size, brain mass and body shape were quantified. Surprisingly, both gill size and brain mass showed high levels of developmental plasticity. We suggest that high levels of plasticity, particularly in the gill size of P. multicolor, reflects low costs of maintaining the plastic response, even in relatively isolated populations.  相似文献   

8.
以5种川西北沙化草地自然留存植物沙生苔草(Carex praeclara)、赖草(Leymus secalinus)、紫花列当(Orobanche coerulescens)、藏茴香(Carum carvi)和地八角(Astragalus bhotanensis)为研究对象,通过测定5种草地植物的表观性状、构件含水量和生物量及其分配,分析5种植物的生长发育、资源分配对沙化生境的响应差异,探讨5种植物对沙化地生境的应对策略与适应机理。结果表明,1)5种植物的表观性状具有极显著差异(P0.01),沙生苔草通过冠幅,赖草通过根茎,地八角通过深根系,紫花列当和藏茴香通过扩大有性生殖来适应沙化生境。2)5种植物的含水量及其配比均存在极显著差异(P0.01),沙生苔草、赖草和地八角的水分优先分配到生殖枝,紫花列当优先分配到茎叶,藏茴香则采用相对均衡的水分分配方式。3)5种植物的生物量及其分配也存在极显著差异(P0.01),沙生苔草生物量优先分配到根茎,赖草优先分配到地上茎叶,紫花列当优先分配到生殖枝,地八角优先分配到根部,而藏茴香则相对均衡的分配生物量到各构件。5种沙生植物对资源权衡分配的方式不同,但均能通过表型可塑性、水分利用能力和生物量分配等应对策略来获取或分配有限的可利用资源,增加其对生境的适应性,得以在沙化草地中留存下来。  相似文献   

9.
During the last decades the study of functional morphology received more attention incorporating more detailed data corresponding to the internal anatomy that together contribute for a better understanding of the functional basis in locomotion. Here we focus on 2 lizard families, Tropiduridae and Liolaemidae, and use information related to muscle‐tendinous and external morphology traits of hind legs. We investigate whether the value of the traits analyzed tend to exhibit a reduced phenotypic variation produced by stabilizing selection, and whether species showing specialization in their habitat use will also exhibit special morphological features related to it. As a result, we identified that evolution of hind limb traits is mainly explained by the Ornstein–Uhlenbeck model, suggesting stabilizing selection. Liolaemids and tropidurids show clear ecomorphological trends in the variables considered, with sand lizards presenting the most specialized morphological traits. Some ecomorphological trends differ between the 2 lineages, and traits of internal morphology tend to be more flexible than those of external morphology, restricting the ability to identify ecomorphs shared between these 2 lineages. Conservative traits of external morphology likely explain such restriction, as ecomorphs have been historically defined in other lizard clades based on variation of external morphology.  相似文献   

10.
Biology textbooks describe the small changes in the beaks of the Galápagos finches as exemplars of how birds evolve in response to environmental changes. However, recent studies of the abundant fossil birds at Rancho La Brea find no evidence of evolutionary responses to the dramatic climate changes of the glacial–interglacial cycle over the past 35 000 years: none of the large birds exhibit any change in body size or limb proportions, even during the last glacial maximum approximately 18 000–20 000 years ago, when the southern California chaparral was replaced by snowy coniferous forests. However, these are all large birds with large ranges and broad habitat preferences, capable of living in many different environments. Perhaps the smaller birds at La Brea, which have smaller home ranges and narrower habitats, might respond to climate more like Galápagos finches. The only 3 common small birds at La Brea are the western meadowlark, the yellow‐billed magpie and the raven. In this study, we demonstrate that these birds also show complete stasis over the last glacial–interglacial cycle, with no statistically significant changes between dated pits. Recent research suggests that the small‐scale changes over short timescales seen in the Galápagos finches are merely fluctuations around a stable morphology, and rarely lead to long‐term accumulation of changes or speciation. Instead, the prevalence of stasis supports the view that long‐term directional changes in morphology are quite rare. While directional changes in morphology occur frequently over short (<1 ka) timescales, in the long term such changes only rarely remain stable for long enough to appear in the fossil record.  相似文献   

11.
The life history of many animals includes periods of food shortage. Two behavioral strategies are involved in small mammals in response to food shortage: an increase in activity behavior, representing the increased foraging or migratory behavior, and a decrease in activity level, serving as a mechanism for conserving energy. However, it is uncertain whether animals adopt both strategies in response to food shortage, and whether hormone and neuroendocrine mechanisms are involved in both strategies. In the present study, changes in behavior and metabolic rate were examined in food‐deprived striped hamsters (Cricetulus barabensis). The effects of leptin supplement on activity behavior, metabolic rate and hypothalamic neuropeptide gene expression were also examined. The behavior of food‐deprived hamsters significantly changed with photoperiod phases: with increasing activity during the dark phase compared to those fed ad libitum, whereas decreasing activity and simultaneously increasing resting behavior during the light phase. Resting metabolic rate, body mass, and masses of fat depots and digestive tracts significantly decreased in food‐deprived hamsters compared with ad libitum controls. Leptin supplement tended to attenuate the increased activity in the dark phase. Gene expression of hypothalamic neuropeptide Y (NPY) was significantly upregulated in food‐deprived hamsters, while was significantly attenuated by exogenous leptin. These findings suggest that both behavior strategies are important behavioral adjustments in free‐living animals to cope with food shortage. Leptin and hypothalamic NPY gene expression may be involved in the adjustments of physiology and behavior in animals demonstrating a hyperactivity strategy in response to food shortage.  相似文献   

12.
为了探讨异质生境条件对羊草(Leymus chinensis)过氧化物同工酶表达的影响,揭示羊草种群对不同土壤生境的响应机制,并为植物的趋异适应和生态可塑性研究提供依据,对扎龙自然保护区内的3种不同生境沙土、碱土、草甸土中生长的3种羊草过氧化物同工酶进行了研究。结果表明:碱土生境条件下羊草条带数最多,草甸土羊草条带数最少;在同一生境条件下,羊草根系的过氧化物酶的条带数最多,叶的条带数最少。其中,迁移率(Rf)值为0.08、0.10、0.17的条带是主带,在7个样品中出现;Rf值为0.35、0.73的条带是弱带,只在1-2个样品中出现;叶片的Shannon-Weinner指数在3个生境间变化较大,根茎的变化较小。因此,异质生境导致了扎龙自然保护区内的羊草过氧化物同工酶的表达存在差异。  相似文献   

13.
Six Eurasian red squirrels (Sciurus vulgaris orientis), victims of road traffic found during 2002 and 2004 near the Noppro Forest Park in Ebetsu, Hokkaido, Japan, were examined for the presence of Babesia parasites. Three of the six squirrels exhibited positive signals by nested PCRs targeting both the 18S rRNA and beta-tubulin genes. Three squirrels proved to be infected with a B. microti-like parasite as evidenced by sequencing the amplified DNAs and by the morphology of the intraerythrocytic parasites. Genotypically, however, the parasite appeared to be of a new type, as it was clearly distinguishable from any of the known types that have previously been reported in various wild animals. This is the first report showing molecular evidence for the presence of B. microti-like parasites in Sciuridae.  相似文献   

14.
Individuals that inhabit broad elevational ranges may experience unique environmental challenges. Because temperature decreases with increased elevation, the ectotherms living at high elevations have to manage limited activity time and high thermoregulatory effort. The resting metabolic rate (RMR) of a postabsorptive animal is related to its total energy requirements as well as many other fitness traits. Mesquite lizards (Sceloporus grammicus) living on La Malinche Volcano, Mexico, inhabit a wide elevational range with some populations apparently thriving above the tree line. We measured the RMR of lizards from different elevations (i.e., 2,600, 3,200, and 4,100 m) at four ecologically relevant temperatures (i.e., 15, 25, 30, and 35 °C) and found that RMR of mesquite lizards increased with temperature and body mass. More importantly, lizards from the high‐elevation population had mass specific RMR that was higher at all temperatures. While the higher RMRs of high‐elevation populations imply higher metabolic costs at a given temperature these lizards were also smaller. Both of these traits may allow these high elevation populations to thrive in the face of the thermal challenges imposed by their environment.  相似文献   

15.
本研究以陇南山区黄瑞香（Daphne giraldii）天然种群为研究对象，分析了半阳坡和半阴坡生境下黄瑞香天然种群种子幼苗转化率，实生苗年龄结构和数量，生长状况，干物质积累与分配，并对影响黄瑞香实生苗生长发育的环境因子、生境因子进行了相关性分析。结果表明：半阳坡和半阴坡黄瑞香种子幼苗转化率均较低，且实生苗密度均随苗龄的增长而减小；黄瑞香实生苗各生长指标在后期生长中表现为半阳坡>半阴坡，叶面积和主根长则相反；两个生境黄瑞香实生苗干质量积累随苗龄增长而增加，且半阳坡>半阴坡；实生苗冠幅、高度和根茎干重与总盖度、灌木层盖度、草本层盖度、海拔呈负相关关系，与土壤有机质、速效氮、速效磷和速效钾含量呈正相关关系。土壤条件和总盖度是影响黄瑞香实生苗更新的主要因子，半阳坡生境更有利于黄瑞香实生苗的生长发育。  相似文献   

16.
A variety of methods have been developed to use bovid postcranial elements in the functional morphology approach to paleohabitat prediction. This study represents a first attempt at testing morphometric methods based on astragalus and phalanges on extant mountain‐dwelling bovids and insular fossil bovids from Sardinia assigned to the so‐called ‘Nesogoral group’, already regarded as close to the Caprini tribe. We intended to answer the questions whether a classic four‐habitats model could be successfully applied to extant mountain‐dwelling bovids, and whether results obtained could support the hypothesis of a radiative evolution for the Sardinian bovids. Results obtained, on the one hand, highlighted some inadequacies of the method if not applied to African bovids; on the other hand, they stressed the difficulties of discriminating habitat preferences of Sardinian taxa only based on biometry of astragalus and phalanges. Nonetheless, statistical habitat predictions suggest the contemporaneous presence in Sardinia of bovids having about the same size, but inhabiting different environments, giving support to the hypothesis that Sardinian representatives of the genus Nesogoral originated from a still unknown ancestor by an adaptive radiation evolutionary process.  相似文献   

17.
采用样线法以巢址为指标在红花尔基樟子松林国家级自然保护区对松鼠的生境保护选择进行了定量研究。使用样线法进行调查,共获取147个巢样方和160个对照样方,对每个样方分别测定了8个环境参数。主成分分析结果表明,影响松鼠巢址选择的诸因素重要性依次为：林型、生境的郁闭程度、生境所处坡向坡位。松鼠显著倾向于在利用苔草樟子松林,随机利用其他类型樟子松林,而对杨桦林等则倾向回避。松鼠巢树周围的树木密度和多样性显著高于对照样方。巢址生境多位于南向的中、下坡位。  相似文献   

18.
This study evaluates binding of bacterial lipopolysaccharide (LPS) by splenic macrophages from golden-mantled ground squirrels (Spermophilus lateralis, GMGS), a hibernating mammal, at a variety of in vitro incubation temperatures to determine whether this aspect of immune function is effective at low body temperatures. LPS-binding by ground squirrel macrophages was compared to that of rat splenic macrophages. Macrophages were collected from squirrels at discreet stages in their annual cycle and incubated with fluorescein-labeled LPS (LPS-FITC). The percentage of GMGS that bound LPS-FITC did not change as a function of hibernation season or as a function of incubation temperature. The total amount of LPS-FITC bound per cell was similarly unaffected by season or temperature, however, macrophages from torpid squirrels bound more LPS-FITC than cells from normothermic squirrels. Macrophages of golden-mantled ground squirrels bind LPS at a wide range of temperatures throughout their annual cycle; an ability shared between hibernators and non-hibernators alike.  相似文献   

19.
Accurate prediction of meat yield in live animals may allow more efficient genetic improvement of meat yield in farm-raised catfish. An initial trial with 30 channel catfish demonstrated significant correlations among weight-adjusted residuals for muscle area measured from transverse ultrasound images and transverse sections at five locations along the trunk musculature (r = 0.30 to 0.70). Relationships of weight-adjusted residuals for three meat yield traits (carcass, whole fillet, and shank fillet) with weight-adjusted residuals for 15 external body shape measurements and five transverse ultrasound measurements of muscle area were determined for 51 female and 91 male channel x blue catfish backcross hybrids. Compared to males, females had smaller heads; deeper, wider, shorter bodies; larger ultrasound muscle area; and higher meat yield. Correlations between carcass traits and body shape and carcass traits and ultrasound measurements were generally higher for females than for males. Correlations among carcass traits and ultrasound muscle area were typically higher than correlations among carcass traits and external body shape in both sexes. A single ultrasound measurement explained 40 to 50% and 16 to 23% of the variation in meat yield traits of females and males, respectively. The best three-variable model using ultrasound and body shape traits explained 48 to 56% and 31 to 38% of the variation in meat yield traits in females and males, respectively. Differences between males and females for the variability in meat yield traits explained by the models may be related to sexual dimorphism for body shape and fillet yield observed in catfish. Ultrasound has potential for predicting meat yield in live fish, but improved prediction accuracy is needed. Differences in meat yield traits between males and females and among individuals within sexes suggest that selecting for fish with smaller heads and deeper, shorter body shape posterior to the visceral cavity will increase meat yield in catfish.  相似文献   

20.
飞蝗在田间有群居型和散居型两种表型,两型间可以相互转变,这种转变是表型可塑性过程。表型可塑性是昆虫对环境变化的响应,通过表型改变来适应恶劣环境达到生存繁衍的目的。群居型和散居型蝗虫在体表颜色、外部形态、发育及生理特征、行为参数等方面都存在明显差异。总结蝗虫表型可塑性调控机制研究进展,并对未来趋势进行了展望,以期控制蝗虫的危害。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号