Exaptation and the evolution of dealation in insects

This paper presents the results of an empirical test of the hypothesis that the evolution of dealation, or self-inflicted removal of wings, is favored in some insect species by the pre-existence of a physiological response of enhanced reproduction following dealation. Two Orthopteran species that do not naturally shed their wings are studied, Teleogryllus oceanicus and Gryllus firmus. The hypothesis that enhanced reproduction following dealation is accompanied by histolysis of the wing muscles is also examined. Dealation increases the rate of egg production in both species. However, total fecundity is not increased by dealation. Wing muscle histolysis is increased by dealation and there is a significant correlation between the degree of histolysis and cumulative egg production to days 4 and 7. It is suggested that Orthoptera are “preadapted” for the evolution of dealation and that ecological factors rather than physiological are most important in determining its appearance in various species.     

Seeds of future past: climate change and the thermal memory of plant reproductive traits

Plant persistence and migration in face of climate change depends on successful reproduction by seed, a central aspect of plant life that drives population dynamics, community assembly and species distributions. Plant reproduction by seed is a chain of physiological processes, the rates of which are a function of temperature, and can be modelled using thermal time models. Importantly, while seed reproduction responds to its instantaneous thermal environment, there is also evidence of phenotypic plasticity in response to the thermal history experienced by the plant's recent ancestors, by the reproducing plant since seedling establishment, and by its seeds both before and after their release. This phenotypic plasticity enables a thermal memory of plant reproduction, which allows individuals to acclimatise to their surroundings. This review synthesises current knowledge on the thermal memory of plant reproduction by seed, and highlights its importance for modelling approaches based on physiological thermal time. We performed a comprehensive search in the Web of Science and analysed 533 relevant articles, of which 81 provided material for a meta‐analysis of thermal memory in reproductive functional traits based on the effect size Zr. The articles encompassed the topics of seed development, seed yield (mass and number), seed dormancy (physiological, morphological and physical), germination, and seedling establishment. The results of the meta‐analysis provide evidence for a thermal memory of seed yield, physiological dormancy and germination. Seed mass and physiological dormancy appear to be the central hubs of this memory. We argue for integrating thermal memory into a predictive framework based on physiological time modelling. This will provide a quantitative assessment of plant reproduction, a complex system that integrates past and present thermal inputs to achieve successful reproduction in changing environments. The effects of a warming environment on plant reproduction cannot be reduced to a qualitative interpretation of absolute positives and negatives. Rather, these effects need to be understood in terms of changing rates and thresholds for the physiological process that underlie reproduction by seed.     

Calcitonin-like diuretic hormones in insects

Insect neuropeptides control various biological processes including growth, development, homeostasis and reproduction. The calcitonin-like diuretic hormone (CT/DH) is one such neuropeptide that has been shown to affect salt and water transport by Malpighian tubules of several insects. With an increase in the number of sequenced insect genomes, CT/DHs have been predicted in several insect species, making it easier to characterize the gene encoding this hormone and determine its function in the species in question. This mini review summarizes the current knowledge on insect CT/DHs, focusing on mRNA and peptide structures, distribution patterns, physiological roles, and receptors in insects.     

Longevity and ageing: appraising the evolutionary consequences of growing old

Senescence or ageing is an increase in mortality and/or decline in fertility with increasing age. Evolutionary theories predict that ageing or longevity evolves in response to patterns of extrinsic mortality or intrinsic damage. If ageing is viewed as the outcome of the processes of behaviour, growth and reproduction then it should be possible to predict mortality rate. Recent developments have shown that it is now possible to integrate these ecological and physiological processes and predict the shape of mortality trajectories. By drawing on the key exciting developments in the cellular, physiological and ecological process of longevity the evolutionary consequences of ageing are reviewed. In presenting these ideas an evolutionary demographic framework is used to argue how trade-offs in life-history strategies are important in the maintenance of variation in longevity within and between species. Evolutionary processes associated with longevity have an important role in explaining levels of biological diversity and speciation. In particular, the effects of life-history trait trade-offs in maintaining and promoting species diversity are explored. Such trade-offs can alleviate the effects of intense competition between species and promote species coexistence and diversification. These results have important implications for understanding a number of core ecological processes such as how species are divided among niches, how closely related species co-occur and the rules by which species assemble into food-webs. Theoretical work reveals that the proximate physiological processes are as important as the ecological factors in explaining the variation in the evolution of longevity. Possible future research challenges integrating work on the evolution and mechanisms of growing old are briefly discussed.     

Social contraception in naked mole-rats and marmoset monkeys

This review summarizes some of the recent advances in our understanding of the social suppression of reproduction. The subject is considered mainly at the physiological level in two mammalian species which display social suppression of reproduction to an extreme degree: the eusocial naked mole-rat, Heterocephalus glaber , and the common marmoset monkey, Callithrix jacchus . Such complete social control of reproduction provides useful models to study basic neuroendocrine and physiological mechanisms involved in mammalian reproduction.     

Physiological performance and xylem water isotopic composition underlie gender‐specific responses in the dioecious shrub Corema album

Gender‐specific requirements of reproduction in dioecious species can lead to different physiological responses in male and female plants, made in relation to environmental constraints, and influencing growth, survival and population structure. Gender‐related physiological differences and seasonal responses, indicating the existence of compensatory mechanisms of reproduction, were examined during a drought year in the dioecious shrub species Corema album. To integrate aboveground and belowground physiological responses, chlorophyll fluorescence, leaf gas exchange, water potential and xylem water isotopic composition were monitored throughout the diurnal cycle and annual phenological sequence of the species. Sampling was carried out in Doñana Natural Park (SW Spain) in Mediterranean‐type climate conditions. The gender which bore greater reproductive effort showed higher physiological stress. Intersexual differences in leaf water potential were interpreted as arising from each gender's maximum reproductive allocation; lower values were found during flowering in males and during fruit production in females. Cold temperatures during winter fostered photoinhibitory responses that were most evident in male individuals, as a response to their relatively higher investment in reproduction during flowering. Net assimilation rate was not influenced by reproductive status; however, females tended to show higher values of this parameter at midday. The integrated analysis of photosynthetic variables and water relations indicated a gender effect in the physiological response at midday. The oxygen isotopic composition of xylem water showed a lack of dependence on the water table during the drought period, and indicated intersexual differences in water catchment. Females reached deeper soil layers, suggesting mechanisms compensating for their higher reproductive effort, and giving new evidence of physiological gender dimorphism in the belowground responses of a woody species.     

A proposed classification of environmental adaptation: the example of high altitude

Extreme environments are defined as the opposite of usual environments where the evoked physiological responses are unperceivable, repeatable and adjusted to the constraint. Adaptation strategies to a given environment show three levels: cultural or technological, where a buffer space is built to protect the organism from the hostile milieu, physiological, where temporary adaptive mechanisms are developed, and genetic, where full adaptation is possible with normal life and reproduction. The cost of adaptation increases from the genetic level (minimal cost) to the technological level. These concepts are illustrated by the example of adaptation to altitude hypoxia. The technological level is given by the use of oxygen bottles by high altitude climbers. The physiological level involves various physiological and biological systems (increase in heart rate, ventilation, erythropoiesis, expression of hypoxia-inducible factors, etc.). The genetic level has been reached by some animal species such as Yaks, Llamas, Pikas but has not yet been demonstrated in humans. Diseases developed during exposure to acute or chronic hypoxia may be considered as “adaptive crises” that mimic the transition to a lower energy level of adaptation.     

How to be a chaste species pluralist-realist: the origins of species modes and the synapomorphic species concept

The biological species (biospecies) concept applies only to sexually reproducing species, which means that until sexual reproduction evolved, there were no biospecies. On the universal tree of life, biospecies concepts therefore apply only to a relatively small number of clades, notably plants andanimals. I argue that it is useful to treat the various ways of being a species (species modes) as traits of clades. By extension from biospecies to the other concepts intended to capture the natural realities of what keeps taxa distinct, we can treat other modes as traits also, and so come to understand that theplurality of species concepts reflects the biological realities of monophyletic groups.We should expect that specialists in different organisms will tend to favour those concepts that best represent the intrinsic mechanisms that keep taxa distinct in their clades. I will address the question whether modes ofreproduction such as asexual and sexual reproduction are natural classes, given that they are paraphyletic in most clades.     

Roles of microRNAs in mammalian reproduction: from the commitment of germ cells to peri‐implantation embryos

MicroRNAs (miRNAs) are active regulators of numerous biological and physiological processes including most of the events of mammalian reproduction. Understanding the biological functions of miRNAs in the context of mammalian reproduction will allow a better and comparative understanding of fertility and sterility in male and female mammals. Herein, we summarize recent progress in miRNA‐mediated regulation of mammalian reproduction and highlight the significance of miRNAs in different aspects of mammalian reproduction including the biogenesis of germ cells, the functionality of reproductive organs, and the development of early embryos. Furthermore, we focus on the gene expression regulatory feedback loops involving hormones and miRNA expression to increase our understanding of germ cell commitment and the functioning of reproductive organs. Finally, we discuss the influence of miRNAs on male and female reproductive failure, and provide perspectives for future studies on this topic.     

A note on the nature of correlations between different characteristics of organisms

Different anatomical and physiological characteristics of organisms affect their interreaction with the inorganic world as well as their mutual interreactions. In this way they all may affect indirectly the total rate of reproduction of a species. It is shown that the requirement of a maximum rate of reproduction defines the distribution functions of the different characteristics and through those distribution functions determines statistical correlations between the characteristics.     

Zinc-metalloproteases in insects: ACE and ECE

Research on the angiotensin-converting enzyme (ACE) in insects has substantially advanced during the recent decade. The cloning of this enzyme in many insect species, the determination of the 3D-structure and several molecular and physiological studies have contributed to the characterization of insect ACE as we know it today: a functional enzyme with a putative role in reproduction, development and defense. The discovery of the endothelin-converting enzyme in insects occurred more recently and cloning of the corresponding cDNA has been carried out in only one insect species so far. However, activity studies and analysis of insect genomes indicate that this enzyme is also widely distributed among insect species. Making hypotheses about its putative function would be preliminary, but its wide tissue distribution suggests a major and diverse biological role.     

蜜蜂嗅觉相关蛋白的研究进展

蜜蜂是一类营社会性生活的昆虫,蜂群中的蜂王、工蜂和雄蜂相互依存,各司其职,共同维持着群体严密有序的生活。其中,嗅觉系统在它们的生存和繁衍过程中起到重要的作用。昆虫对气味物质的感受过程是非常复杂的,需要有多种蛋白的参与。研究蜜蜂的化学感受机制可以帮助我们更深入地了解蜜蜂特有的行为及生物学特性。本文重点综述了与蜜蜂嗅觉相关的3种蛋白质的生化特性、分子结构、基因表达及其生理功能等方面的研究进展,以期为今后开展相关研究工作提供理论参考。     

The biological cycles of pelagic copepods in the lakes of Kamchatka

Pelagic species of two copepods (Neutrodiaptomus angustilobus Sars and Cyclops scutifer Sars) occur in lakes of Kamchatka Peninsula.Neutrodiaptomus is monocyclic in all lakes studied. Adult copepods live in the plankton from January till August and produce 5–6 successive generations.The biological cycle of Cyclops scutifer depends on the type of the lake. This species is predominantly monocyclic in lakes with a depth of 20 to 30 m and has a period of reproduction in June–August. In deeper lakes the population is represented by several cohorts. E.g. Lake Dalnee is populated by 5 cohorts with one-year biological cycles. Copepods of each cohort reproduce in a definite season.In years when copepods are not abundant, periods of reproduction for each cohort are relatively short and distinguishable. In years when both major and minor cohorts are abundant, their periods of reproduction become longer and may overlap, which gives the impression of a monocyclic population.Read at the Limnological Congress in Leningrad.     

Reproduction and life history strategies of the common jellyfish, Aurelia aurita, in relation to its ambient environment

The scyphozoan Aurelia aurita (Linnaeus) is a cosmopolitan species, having been reported from a variety of coastal and shelf sea environments around the world. It has been extensively studied over the last 100 years or so, and examination of the literature reveals three striking features: (1) the presence of populations in a wide range of environmental conditions; (2) large inter-population differences in abundance and life history patterns over large and small spatial scales; and (3) inter-annual variability in various aspects of its population dynamics. A. aurita is clearly a highly flexible species that can adapt to a wide range of environmental conditions. While various physiological and behavioural characteristics explain how A. aurita populations can take advantage of their surrounding environment, they do not explain what governs the observed temporal and spatial patterns of abundance, and the longevity or lifespan of populations. Understanding these features is necessary to predict how bloom populations might form. In a given habitat, the distribution and abundance of benthic marine invertebrates have been found to be maintained by four factors: larval recruitment (sexual reproduction), migration, mortality and asexual reproduction. The aims of this review are to determine the role of reproduction and life history strategies of the benthic and pelagic phases of A. aurita in governing populations of medusae, with special attention given to the dynamic interaction between A. aurita and its surrounding physical and biological environment.     

鲣鱼（Katsuwonus pelamis）生物学研究进展

鲣鱼是金枪鱼渔业最为重要的目标鱼种之一,对鲣鱼的生物学研究是对其种群资源进行评估的基础。综述了国外学者对鲣鱼基础生物学研究的进展,从鲣鱼的年龄和生长、繁殖、摄食习性3个方面对以前的研究结论进行整理比较,并总结出所存在的不足及今后可能的发展方向,旨在为开展相关的鲣鱼生物特性研究及对鲣鱼资源的初步评估提供参考依据。     

Doppel蛋白及其对动物生殖的影响

Doppel(简称Dpl)是新发现的一种糖基磷脂酰肌醇锚定(GPI)结构糖蛋白, 在结构上与朊蛋白(Prion protein, PrP)相似, 其编码基因位于朊蛋白编码基因(Prion protein gene, PRNP)下游, 但在生理功能上两者差异较大。Dpl蛋白在成年动物体内的表达主要集中在睾丸组织, 对雄性动物精子完整性、活力以及维持正常受精能力等生殖功能具有重要作用。以下主要综述了Dpl蛋白的生物学特征、生理功能以及对雄性动物生殖调控的影响, 旨在为Dpl蛋白的功能研究和雄性动物生殖调控研究提供理论参考。     

Biological species is the only possible form of existence for higher organisms: the evolutionary meaning of sexual reproduction

   

Consistent holistic view of sexual species as the highest form of biological existence is presented. The Weismann's idea that sex and recombination provide the variation for the natural selection to act upon is dominated in most discussions of the biological meaning of the sexual reproduction. Here, the idea is substantiated that the main advantage of sex is the opposite: the ability to counteract not only extinction but further evolution as well. Living systems live long owing to their ability to reproduce themselves with a high fidelity. Simple organisms (like bacteria) reach the continued existence due to the high fidelity of individual genome replication. In organisms with a large genome and complex development, the achievable fidelity of DNA replication is not enough for the precise reproduction of the genome. Such species must be capable of surviving and must remain unchanged in spite of the continuous changes of their genes. This problem has no solution in the frame of asexual ("homeogenomic") lineages. They would rapidly degrade and become extinct or blurred out in the course of the reckless evolution. The core outcome of the transition to sexual reproduction was the creation of multiorganismic entity - biological species. Individual organisms forfeited their ability to reproduce autonomously. It implies that individual organisms forfeited their ability to substantive evolution. They evolve as a part of the biological species. In case of obligatory sexuality, there is no such a thing as synchronic multi-level selection. Natural selection cannot select anything that is not a unit of reproduction. Hierarchy in biology implies the functional predestination of the parts for the sake of the whole. A crucial feature of the sexual reproduction is the formation of genomes of individual organisms by random picking them over from the continuously shuffled gene pool instead of the direct replication of the ancestor's genome. A clear anti-evolutionary consequence of the sexuality is evident from the fact that the genotypes of the individuals with an enhanced competitiveness are not transmitted to the next generation. Instead, after mating with "ordinary" individuals, these genotypes scatter and rearrange in new gene combinations, thus preventing the winner from exploiting the success.     

Gender-specific costs of reproduction on vegetative growth and physiological performance in the dioecious shrub Corema album

Background and Aims

Reproductive costs imply trade-offs in resource distribution at the physiological level, expressed as changes in future growth and/or reproduction. In dioecious species, females generally endure higher reproductive effort, although this is not necessarily expressed through higher somatic costs, as compensatory mechanisms may foster resource uptake during reproduction.

Methods

To assess effects of reproductive allocation on vegetative growth and physiological response in terms of costs and compensation mechanisms, a manipulative experiment of inflorescence bud removal was carried out in the sexually dimorphic species Corema album. Over two consecutive growing seasons, vegetative growth patterns, water status and photochemical efficiency were measured to evaluate gender-related differences.

Key Results

Suppression of reproductive allocation resulted in a direct reduction in somatic costs of reproduction, expressed through changes in growth variables and plant physiological status. Inflorescence bud removal was related to an increase in shoot elongation and water potential in male and female plants. The response to inflorescence bud removal showed gender-related differences that were related to the moment of maximum reproductive effort in each sexual form: flowering in males and fruiting in females. Delayed costs of reproduction were found in both water status and growth variables, showing gender-related differences in resource storage and use.

Conclusions

Results are consistent with the existence of a trade-off between reproductive and vegetative biomass, indicating that reproduction and growth depend on the same resource pool. Gender-related morphological and physiological differences arise as a response to different reproductive resource requirements. Delayed somatic costs provide evidence of gender-related differences in resource allocation and storage. Adaptive differences between genders in C. album may arise through the development of mechanisms which compensate for the cost of reproduction.     

Life-history strategies in salmonids: the role of physiology and its consequences

Salmonids are some of the most widely studied species of fish worldwide. They span freshwater rivers and lakes to fjords and oceans; they include short- and long-distance anadromous migrants, as well as partially migratory and non-migratory populations; and exhibit both semelparous and iteroparous reproduction. Salmonid life-history strategies represent some of the most diverse on the planet. For this reason, salmonids provide an especially interesting model to study the drivers of these different life-history pathways. Over the past few decades, numerous studies and reviews have been published, although most have focused on ultimate considerations where expected reproductive success of different developmental or life-history strategies are compared. Those that considered proximate causes generally focused on genetics or the environment, with less consideration of physiology. Our objective was therefore to review the existing literature on the role of physiology as a proximate driver for life-history strategies in salmonids. This link is necessary to explore since physiology is at the core of biological processes influencing energy acquisition and allocation. Energy acquisition and allocation processes, in turn, can affect life histories. We find that life-history strategies are driven by a range of physiological processes, ranging from metabolism and nutritional status to endocrinology. Our review revealed that the role of these physiological processes can vary across species and individuals depending on the life-history decision(s) to be made. In addition, while findings sometimes vary by species, results appear to be consistent in species with similar life cycles. We conclude that despite much work having been conducted on the topic, the study of physiology and its role in determining life-history strategies in salmonids remains somewhat unexplored, particularly for char and trout (excluding brown trout) species. Understanding these mechanistic links is necessary if we are to understand adequately how changing environments will impact salmonid populations.