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1.
Many sexually selected traits exhibit phenotypic plasticity. Despite a growing appreciation for the ecological context in which sexual selection occurs, and for the role of plasticity in shaping traits associated with local adaptation and divergence, there is an important gap in knowledge about the onset and duration of plasticity in sexual trait expression. Integrating this temporal dimension of plasticity into models of sexual selection informs our understanding of the information conveyed by sexual traits and our predictions related to trait evolution, and is critical in this time of unprecedented and rapid environmental change. We conducted a systematic review of 869 studies to ask how trait modalities (e.g., visual and chemical) relate to the onset and duration of plasticity in vertebrate sexual signals. We show that this literature is dominated by studies of coloration in birds and fish, and most studies take place during the breeding season. Where possible, we integrate results across studies to link physiology of specific trait modalities with the life stage (e.g., juvenile, breeding, or nonbreeding) during which plasticity occurs in well‐studied traits. Limitations of our review included a lack of replication in our dataset, which precluded formal analysis. We argue that the timing of trait plasticity, in addition to environmental context, is critical for determining whether and how various communication signals are associated with ecological context, because plasticity may be ongoing or occur at only one point in an individual''s lifetime, and determining a fixed trajectory of trait expression. We advocate for careful consideration of the onset and duration of plasticity when analyzing how environmental variation affects sexual trait expression and associated evolutionary outcomes.  相似文献   

2.
3.
Structural equation models (SEMs) are multivariate specifications capable of conveying causal relationships among traits. Although these models offer insights into how phenotypic traits relate to each other, it is unclear whether and how they can improve multiple-trait selection. Here, we explored concepts involved in SEMs, seeking for benefits that could be brought to breeding programs, relative to the standard multitrait model (MTM) commonly used. Genetic effects pertaining to SEMs and MTMs have distinct meanings. In SEMs, they represent genetic effects acting directly on each trait, without mediation by other traits in the model; in MTMs they express overall genetic effects on each trait, equivalent to lumping together direct and indirect genetic effects discriminated by SEMs. However, in breeding programs the goal is selecting candidates that produce offspring with best phenotypes, regardless of how traits are causally associated, so overall additive genetic effects are the matter. Thus, no information is lost in standard settings by using MTM-based predictions, even if traits are indeed causally associated. Nonetheless, causal information allows predicting effects of external interventions. One may be interested in predictions for scenarios where interventions are performed, e.g., artificially defining the value of a trait, blocking causal associations, or modifying their magnitudes. We demonstrate that with information provided by SEMs, predictions for these scenarios are possible from data recorded under no interventions. Contrariwise, MTMs do not provide information for such predictions. As livestock and crop production involves interventions such as management practices, SEMs may be advantageous in many settings.  相似文献   

4.
The objectives of this study were to quantify the errors in economic values (EVs) for traits affected by cost or price thresholds when skewed or kurtotic distributions of varying degree are assumed to be normal and when data with a normal distribution is subject to censoring. EVs were estimated for a continuous trait with dichotomous economic implications because of a price premium or penalty arising from a threshold ranging between −4 and 4 standard deviations from the mean. In order to evaluate the impacts of skewness, positive and negative excess kurtosis, standard skew normal, Pearson and the raised cosine distributions were used, respectively. For the various evaluable levels of skewness and kurtosis, the results showed that EVs can be underestimated or overestimated by more than 100% when price determining thresholds fall within a range from the mean that might be expected in practice. Estimates of EVs were very sensitive to censoring or missing data. In contrast to practical genetic evaluation, economic evaluation is very sensitive to lack of normality and missing data. Although in some special situations, the presence of multiple thresholds may attenuate the combined effect of errors at each threshold point, in practical situations there is a tendency for a few key thresholds to dominate the EV, and there are many situations where errors could be compounded across multiple thresholds. In the development of breeding objectives for non-normal continuous traits influenced by value thresholds, it is necessary to select a transformation that will resolve problems of non-normality or consider alternative methods that are less sensitive to non-normality.  相似文献   

5.
Ecosystem service‐based management requires an accurate understanding of how human modification influences ecosystem processes and these relationships are most accurate when based on functional traits. Although trait variation is typically sampled at local scales, remote sensing methods can facilitate scaling up trait variation to regional scales needed for ecosystem service management. We review concepts and methods for scaling up plant and animal functional traits from local to regional spatial scales with the goal of assessing impacts of human modification on ecosystem processes and services. We focus our objectives on considerations and approaches for (1) conducting local plot‐level sampling of trait variation and (2) scaling up trait variation to regional spatial scales using remotely sensed data. We show that sampling methods for scaling up traits need to account for the modification of trait variation due to land cover change and species introductions. Sampling intraspecific variation, stratification by land cover type or landscape context, or inference of traits from published sources may be necessary depending on the traits of interest. Passive and active remote sensing are useful for mapping plant phenological, chemical, and structural traits. Combining these methods can significantly improve their capacity for mapping plant trait variation. These methods can also be used to map landscape and vegetation structure in order to infer animal trait variation. Due to high context dependency, relationships between trait variation and remotely sensed data are not directly transferable across regions. We end our review with a brief synthesis of issues to consider and outlook for the development of these approaches. Research that relates typical functional trait metrics, such as the community‐weighted mean, with remote sensing data and that relates variation in traits that cannot be remotely sensed to other proxies is needed. Our review narrows the gap between functional trait and remote sensing methods for ecosystem service management.  相似文献   

6.
The appeal of trait‐based approaches for assessing environmental vulnerabilities arises from the potential insight they provide into the mechanisms underlying the changes in populations and community structure. Traits can provide ecologically based explanations for observed responses to environmental changes, along with predictive power gained by developing relationships between traits and environmental variables. Despite these potential benefits, questions remain regarding the utility and limitations of these approaches, which we explore focusing on the following questions: (a) How reliable are predictions of biotic responses to changing conditions based on single trait–environment relationships? (b) What factors constrain detection of single trait–environment relationships, and how can they be addressed? (c) Can we use information on meta‐community processes to reveal conditions when assumptions underlying trait‐based studies are not met? We address these questions by reviewing published literature on aquatic invertebrate communities from stream ecosystems. Our findings help to define factors that influence the successful application of trait‐based approaches in addressing the complex, multifaceted effects of changing climate conditions on hydrologic and thermal regimes in stream ecosystems. Key conclusions are that observed relationships between traits and environmental stressors are often inconsistent with predefined hypotheses derived from current trait‐based thinking, particularly related to single trait–environment relationships. Factors that can influence findings of trait‐based assessments include intercorrelations of among traits and among environmental variables, spatial scale, strength of biotic interactions, intensity of habitat disturbance, degree of abiotic stress, and methods of trait characterization. Several recommendations are made for practice and further study to address these concerns, including using phylogenetic relatedness to address intercorrelation. With proper consideration of these issues, trait‐based assessment of organismal vulnerability to environmental changes can become a useful tool to conserve threatened populations into the future.  相似文献   

7.
Chironomidae are among the most conspicuous and ecological diverse group of freshwater invertebrates. They may dominate unimpacted communities in abundance and biomass, accounting for more than 50% of macroinvertebrate species in standing and flowing waters. In deep zones of eutrophic lakes and highly human-impacted streams, they are often the only family of aquatic insects remaining. In bioassessment programmes, Chironomids are often identified at the family and subfamily levels, due to difficulties in the taxonomic identification of larvae resulting from a high intrinsic morphological similarity. This may potentially result in bias as, similarly to Ephemeroptera, Trichoptera or Plecoptera, Chironomidae species, which are replaced along natural and human-impacted gradients due to differences in their ecological requirements. Recently, multiple trait-based approaches have been proposed to complement taxonomic-based assessment of streams and rivers using macroinvertebrates. However, the lack of specific trait information for Chironomidae prevents their use in the functional assessment of communities. Therefore, here, we aimed to: (1) develop a trait database for European Chironomidae genera that can be used in future bioassessment and ecological studies; (2) evaluate, by multivariate analyses, whether our new database provides additional information on Chironomidae compared to the trait information provided in the commonly used European trait database (Tachet et al., 2010); and (3) determine whether the new information on Eltonian traits (proxy to biological traits) translates the most accepted phylogenetic relationships among Chironomidae subfamilies. We gathered information on 744 species and 178 genera, for 37 traits covering 186 trait categories, and found substantial differences between our database and the commonly used European trait database. In addition, available information on traits was not always in agreement with phylogenetic relationships among subfamilies. Orthocladiinae and Chironominae which are considered sister groups in evolutionary terms actually showed confident trait relatedness based on Eltonian traits tree while the remaining relationships between subfamilies are questionable. In addition, different traits can occur in closely related taxa depending on the environmental drivers operating on their habitats. Our study reveals that the usually accepted redundancy within the Chironomidae family and subfamilies must be a product of averaging the information from finer taxonomic resolution added to the substantial lack of information for this insect group.  相似文献   

8.
One of ecology's grand challenges is developing general rules to explain and predict highly complex systems. Understanding and predicting ecological processes from species' traits has been considered a ‘Holy Grail’ in ecology. Plant functional traits are increasingly being used to develop mechanistic models that can predict how ecological communities will respond to abiotic and biotic perturbations and how species will affect ecosystem function and services in a rapidly changing world; however, significant challenges remain. In this review, we highlight recent work and outstanding questions in three areas: (i) selecting relevant traits; (ii) describing intraspecific trait variation and incorporating this variation into models; and (iii) scaling trait data to community‐ and ecosystem‐level processes. Over the past decade, there have been significant advances in the characterization of plant strategies based on traits and trait relationships, and the integration of traits into multivariate indices and models of community and ecosystem function. However, the utility of trait‐based approaches in ecology will benefit from efforts that demonstrate how these traits and indices influence organismal, community, and ecosystem processes across vegetation types, which may be achieved through meta‐analysis and enhancement of trait databases. Additionally, intraspecific trait variation and species interactions need to be incorporated into predictive models using tools such as Bayesian hierarchical modelling. Finally, existing models linking traits to community and ecosystem processes need to be empirically tested for their applicability to be realized.  相似文献   

9.
鉴定畜禽重要生产性状形成的关键遗传因子,揭示其产生的分子遗传机制,对动物新品种的培育及特色遗传资源的开发利用具有重要意义。高通量分析技术诞生前,标记数量性状位点(quantitative trait loci,QTL)连锁分析和候选基因分析法作为鉴定畜禽生产性状QTL和主效基因主要方法,但由于其技术局限性,性状因果基因鉴定的效率并不高。人类基因组计划(human genome project, HGP)开启了以大数据为特征的生命科学研究的序幕,在HGP完成后的20余年间,快速发展的高通量分析技术使人们研究生物学问题的思路和方法发生了巨大改变。本综述就近年来被广泛用于畜禽重要性状的候选基因定位的方法与技术进行了较全面的综述,以期为同行提供参考。  相似文献   

10.
Fluctuating asymmetry of morphological traits is thought to reflect the capacity of a genotype to produce an integrated, functional phenotype. I tested three predictions. (1) In a polygynous breeding system, under intense sexual selection on males, breeding males should show greater symmetry in bilaterally symmetrical traits than non-breeding males or females. (2) If these traits are under stabilizing selection, highly symmetrical individuals also should be modal phenotypes, thus near the mean value for that trait, whereas individuals with increased asymmetry should represent marginal phenotypes, near the extremes of the distribution for that trait. (3) Differences in the intensity of sexual selection should be reflected in differences in the degree of fluctuating asymmetry between sexes among populations. I examined the relationship between male breeding status and the degree of fluctuating asymmetry of four bilaterally symmetrical- traits, preorbital and preopercular pores and pectoral and pelvic fin rays, in two populations of Pecos pupfish which differed in the intensity of sexual selection. These traits do not function in male-male competition or female choice, thus are not directly affected by sexual selection. In Mirror Lake breeding males, as a group, were most symmetrical for all four traits, while non-breeding males and females showed higher levels of fluctuating asymmetry. Similarly, symmetrical individuals also represented modal phenotypes for four traits (breeding males), and for three traits (non-breeding males and females). These patterns were not seen in the Lake Francis population, where breeding males were as asymmetrical as non-breeding males and females, and the degree of fluctuating symmetry did not differ between modal and marginal phenotypes for any of the four traits. When ecological conditions favour intense sexual selection, either through female choice, male-male competition, or both, breeding males represent the most fit phenotypes. Thus sexual selection reinforces the effects of stabilizing selection on characters that do not function as secondary sexual traits. However, when sexual selection is relaxed, differences between sexes disappear.  相似文献   

11.
The immune system plays an important role in enhancing an individual's ability to survive in a world inhabited by pathogens and parasites. The innate immune system is regulated by processes encoded in an individual's genome, providing an avenue for selection to act on this system, as well as the phenotypic relationships generated between this system and other traits of interest. While relationships between innate immunity and endocrine traits (e.g. testosterone) have been reported often in the literature, these relationships are complex and may differ under varying environmental conditions. To better understand the relative contribution of innate immunity (or an endocrine or behavioral trait) to a phenotypic correlation with another trait, an estimation of the underlying heritable genetic variation of the trait of interest is needed. An upper level estimate of the heritability of such traits can be obtained from calculating its repeatability. We conducted a literature review to determine how often repeated samples of measures of innate immune function were conducted and repeatability estimates obtained. This review revealed a very limited number of repeatability estimates, with a large range (0.0–0.9); estimates were exclusively from livestock that have undergone strong artificial selection. This observation of the present literature suggests more work is needed in non-domesticated and free-living animals to begin to understand the underlying genetic contribution of innate immune function to phenotypic correlations of interest (e.g. testosterone and immunity) to behavioral ecologists, evolutionary physiologists and ecoimmunologists.  相似文献   

12.
Slate J 《Molecular ecology》2005,14(2):363-379
Over the last 15 years quantitative trait locus (QTL) mapping has become a popular method for understanding the genetic basis of continuous variation in a variety of systems. For example, the technique is now an integral tool in medical genetics, livestock production, plant breeding and population genetics of model organisms. Ten years ago, it was suggested that the method could be used to understand continuous variation in natural populations. In this review I: (i) clarify what is meant by natural population in the QTL context, (ii) discuss whether evolutionary biologists have successfully mapped QTL in natural populations, (iii) highlight some of the questions that have been addressed by QTL mapping in natural populations, (iv) describe how QTL mapping can be conducted in unmanipulated natural populations, (v) highlight some of the limitations of QTL mapping and (vi) try to predict some future directions for QTL mapping in natural populations.  相似文献   

13.
  • 1 Relating species traits to habitat characteristics can provide important insights into the structure and functioning of stream communities. However, trade‐offs among species traits make it difficult to predict accurately the functional diversity of freshwater communities. Many authors have pointed to the value of working with groups of organisms as similar as possible in terms of relationships among traits and have called for definition of groups of organisms with similar suites of attributes.
  • 2 We used multivariate analyses to examine separately the relationships among 11 biological traits and among 11 ecological traits of 472 benthic macroinvertebrate taxa (mainly genera). The main objective was to demonstrate (1) potential trade‐offs among traits; (2) the importance of the different traits to separate systematic units or functional groupings; and (3) uniform functional groups of taxa that should allow a more effective use of macroinvertebrate biological and ecological traits.
  • 3 We defined eight groups and 15 subgroups according to a biological trait ordination which highlighted size (large to small), reproductive traits (K to r strategists), food (animal to plant material) and feeding habits (predator to scraper and/or deposit feeder) as ‘significant’ factors determining the ordination of taxa. This ordination partly preserved phylogenetic relationships among groups.
  • 4 Seven ecological groups and 13 ecological subgroups included organisms with combinations of traits which should be successively more adequate in habitats from the main channel to temporary waters, and from the crenon to the potamic sections of rivers, and to systems situated outside the river floodplain. These gradients corresponded to a gradual shift from (1) rheophilic organisms that lived in the main channel of cold oligotrophic mountain streams to (2) animals that preferred eutrophic habitats of still or temporary waters in lowlands. The groups with similar ecological traits had a more diverse systematic structure than those with similar biological traits.
  • 5 Monitoring and assessment tools for the management of water resources are generally more effective if they are based on a clear understanding of the mechanisms that lead to the presence or absence of species groups in the environment. We believe that groups with similar relationships among their species traits may be useful in developing tools that measure the functional diversity of communities.
  相似文献   

14.
Even with increasing interest in the ecological importance of intraspecific trait variation (ITV) for better understanding ecological processes, few studies have quantified ITV in seedlings and assessed constraints imposed by trade‐offs and correlations among individual‐level leaf traits. Estimating the amount and role of ITV in seedlings is important to understand tree recruitment and long‐term forest dynamics. We measured ten different size, economics, and whole leaf traits (lamina and petiole) for more than 2,800 seedlings (height ≥ 10 cm and diameter at breast height < 1 cm) in 283 seedling plots and then quantified the amount of ITV and trait correlations across two biological (intraspecific and interspecific) and spatial (within and among plots) scales. Finally, we explored the effects of trait variance and sample size on the strength of trait correlations. We found about 40% (6%–63%) variation in leaf‐level traits was explained by ITV across all traits. Lamina and petiole traits were correlated across biological and spatial scales, whereas leaf size traits (e.g., lamina area) were weakly correlated with economics traits (e.g., specific lamina area); lamina mass ratio was strongly related to the petiole length. Trait correlations varied among species, plots, and different scales but there was no evidence that the strength of trait relationships was stronger at broader than finer biological and spatial scales. While larger trait variance increased the strength of correlations, the sample size was the most important factor that was negatively related to the strength of trait correlations. Our results showed that a large amount of trait variation was explained by ITV, which highlighted the importance of considering ITV when using trait‐based approaches in seedling ecology. In addition, sample size was an important factor that influenced the strength of trait correlations, which suggests that comparing trait correlations across studies should consider the differences in sample size.  相似文献   

15.
The striking diversity of sperm shape across the animal kingdom is still poorly understood. Postcopulatory sexual selection is an important factor driving the evolution of sperm size and shape. Interestingly, morphometric sperm traits, such as the length of the head, midpiece and flagellum, exhibit a strong positive phenotypic correlation across species. Here we used recently developed comparative methods to investigate how such phenotypic correlations between morphometric sperm traits may evolve. We compare allometric relationships and evolutionary trajectories of three morphometric sperm traits (length of head, midpiece and flagellum) in passerine birds. We show that these traits exhibit strong phenotypic correlations but that allometry varies across families. In addition, the evolutionary trajectories of the midpiece and flagellum are similar while the trajectory for head length differs. We discuss our findings in the light of three scenarios accounting for correlated trait evolution: (i) genetic correlation; (ii) concerted response to selection acting simultaneously on different traits; and (iii) phenotypic correlation between traits driven by mechanistic constraints owing to selection on sperm performance. Our results suggest that concerted response to selection is the most likely explanation for the phenotypic correlation between morphometric sperm traits.  相似文献   

16.
何芸雨  郭水良  王喆 《植物生态学报》2019,43(12):1021-1035
植物功能性状权衡关系反映了植物在资源获取与分配中采取的不同策略, 是近年来生态学研究的一个热点问题。该综述从研究范围、叶性状、器官和植物类群4个方面入手, 简要介绍植物功能性状关系研究在近10余年是如何在叶经济谱(LES)的基础上逐渐扩展和深入的。1)相关研究拓展到全球更多极端环境与特殊气候地区, 发现在不同的气候环境条件下, 植物叶片功能性状关系相对稳定, 植物种内的功能性状关系已被证实与LES相似; 2)功能性状网络从最初的6个经济性状扩展到叶片的分解、燃烧和水力等性状, 发现叶片的分解速率和可燃性均与叶片形态性状、养分含量等显著相关, 但叶片水力性状与经济性状的关系则取决于所研究的物种及生存环境的水分条件; 3)研究对象从植物叶片拓展到了根、茎、花、种子及植株整体, 叶片的比叶质量与茎的木质密度、种子大小相耦合, 但叶片形态性状与根和花的相关性状却无显著相关关系, 证明这些器官可能是独立进化的; 4) LES可以很好地解释特殊维管植物的生存适应策略: 入侵植物具有较高的资源利用效率和更快的相对生长速率, 在LES中处于“低投入-快速回报”的一端; 食虫植物的叶片特化为捕食器官, 光合作用及生长速率相对较低, 居于LES “高投入-缓慢回报”的另一端, 此外, 无论是最古老的种子植物苏铁属(Cycas)植物, 或是蕨类和变水植物(苔藓和地衣), 其功能性状关系都与LES大致相同。该文梳理了功能性状关系研究的进展脉络, 提出了一些建议, 期望为未来植物功能性状关系研究的选题和发展提供一些参考。  相似文献   

17.
Evolutionary radiations are responsible for much of Earth's diversity, yet the causes of these radiations are often elusive. Determining the relative roles of adaptation and geographic isolation in diversification is vital to understanding the causes of any radiation, and whether a radiation may be labeled as “adaptive” or not. Across many groups of plants, trait–climate relationships suggest that traits are an important indicator of how plants adapt to different climates. In particular, analyses of plant functional traits in global databases suggest that there is an “economics spectrum” along which combinations of functional traits covary along a fast–slow continuum. We examine evolutionary associations among traits and between trait and climate variables on a strongly supported phylogeny in the iconic plant genus Protea to identify correlated evolution of functional traits and the climatic‐niches that species occupy. Results indicate that trait diversification in Protea has climate associations along two axes of variation: correlated evolution of plant size with temperature and leaf investment with rainfall. Evidence suggests that traits and climatic‐niches evolve in similar ways, although some of these associations are inconsistent with global patterns on a broader phylogenetic scale. When combined with previous experimental work suggesting that trait–climate associations are adaptive in Protea, the results presented here suggest that trait diversification in this radiation is adaptive.  相似文献   

18.
鱼类生长性状改良及其调控研究进展   总被引:1,自引:0,他引:1  
水产种质资源是水产业持续、健康、稳定发展的重要物质基础,培育出优质、高产、高效的新品种是保障养殖业可持续发展的关键。鱼类的生长速度是评价养殖价值的重要指标,也是选育的重要性状之一,然而鱼类育种的基础薄弱,鱼类品种改良的理论基础和技术创新一直困扰着鱼类育种工作。本文从内因(遗传等)和外因(食物、温度、溶氧及种内种间关系等)两方面探讨了各因子对鱼类生长的影响,依此就鱼类生长性状的调控策略进行了述评,并对其做了展望,以期为鱼类生长性状的改良及其调控提供理论依据和指导。  相似文献   

19.
Plant traits are fundamental components of the ecological strategies of plants, relating to how plants acquire and use resources. Their study provides insight into the dynamics of species geographical ranges in changing environments. Here, we assessed the variation in trait values at contrasting points along an environmental gradient to provide insight into the flexibility of species response to environmental heterogeneity. Firstly, we identified how commonly measured functional traits of four congeneric species (Banksia baxteri, B. coccinea, B. media and B. quercifolia) varied along a longitudinal gradient in the South Western Australian Floristic Region. This regional gradient provides significant variation in moisture, temperature and soil nutrients: soil nitrogen content decreases with declining rainfall and increasing temperature. We hypothesized that (i) the regional pattern in trait–environment associations across the species would match those observed on a global scale and (ii) that the direction and slopes of the within‐species relationships would be similar to those across species for each of the measured traits. Along the regional gradient we observed strong shifts in trait values, and cross‐species relationships followed the expected trend: specific leaf area was significantly lower, and leaf Narea and seed dry mass significantly higher, at the drier end of the rainfall gradient. However, traits within species were generally not well correlated with habitat factors: we found weak patterns among populations, either due to the small ecological gradient or perhaps because fine‐scale structuring among populations (at a micro‐evolutionary scale) was low due to high gene flow within species. Understanding how species traits shift as a result of climatic influences, both at the regional (across species) and local (within species) scale, provides insight into plant adaptation to the environment. Such studies have important applications for conservation biology and population management in the face of global change.  相似文献   

20.
游光霞  张学勇 《遗传》2007,29(7):881-888
许多重要农艺性状如产量、品质、抗逆性等多表现为数量性状, 是由多个基因和环境共同作用的结果, 对其遗传基础的研究比较困难。近年发展起来的以选择牵连效应分析为基础, 通过标记/性状之间的关联分析方法为这些性状的作图和遗传解析提供了新的手段, 也为作物的分子设计育种提供了新的思路, 其与QTL作图结果互相验证、互相补充, 必将促进数量遗传学、应用基因组学和育种学的发展。文章对关联分析的思路、方法、优缺点及应用时应注意的问题进行了比较系统的介绍。  相似文献   

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