mode of reproduction
Recently Published Documents

Chlorella-like green algae that reproduce only asexually by immotile autospores or motile zoospores are the most typical inhabitants of non-aquatic environments. They have a simple morphology that hampers their differentiation, but algae of such habit represent a diverse array of lineages, which are mostly in the classes Chlorophyceae and Trebouxiophyceae. One of these lineages is the order Watanabeales (Watanabea clade; Trebouxiophyceae), which comprises 10 genera that share a distinct mode of reproduction through unequally sized autospores. Most of these genera account for a few species that are rarely recorded in nature. In contrast, the genus Chloroidium is one of the most species-rich and widely distributed members of the order. Three strains of coccoid green alga were isolated during a study of soil algae in the temperate monsoon climate zone of Asia. These strains are described here as a new species, Chloroidium orientalis. SSU and ITS rDNA sequence data, morphological characteristics, and life cycle features differentiate these strains from known members of the genus.

Among ten adult specimens of the Madeiran endemic land snail Leptaxis simia kept in the laboratory, a single clutch of 110 eggs was reared, and the mortality, growth and reproductive capacity of hatchlings over a 1240- day period were monitored. Of 70 hatchlings, 34 survived to complete shell growth at around 640 days. Growth was rapid, and mortality high in the early stages; growth slowed and mortality was very low as full size was approached. Snails kept singly failed to lay any eggs. Among those with potential mates, only three clutches were produced, one of which yielded no hatchlings. Clutches were produced at least five months after shell growth was complete. Mortality increased sharply after the onset of sexual maturity, and the oldest snail survived for three and a half years. The apparently very strictly semelparous mode of reproduction, delayed sexual maturity and relatively long period of juvenile growth are discussed in relation to other species, and to the practical problems of rearing potentially endangered species in captivity.

Paternal genome elimination (PGE) - a type of reproduction in which males inherit but fail to pass on the genome of their father - evolved independently in six to eight arthropod clades. Thousands of species, including several important for agriculture, reproduce via this mode of reproduction. While some of the clades are well established PGE systems, the evidence in globular springtails (Symphypleona) remains elusive, even though they represent the oldest and most species rich clade putatively reproducing via PGE. We sequenced genomic DNA from whole bodies of Allacma fusca males with sufficiently high fractions (31 - 38%) of sperm to conclusively confirm that all the sperm carry one parental haplotype only. Although it is suggestive that the single haplotype present in sperm is maternally inherited, definitive genetic proof of the parent of origin is still needed. The genomic approach we developed allows for detection of genotypic differences between germline and soma in all species with sufficiently high fraction of germline in their bodies. This opens new opportunities for scans for reproductive modes in small animals.

AbstractThis article documents and conceptualizes a mode of reproduction of elites in a society in transition from state domination to market orientation. By focusing on China’ marketization, we explore how parents’ advantageous backgrounds have influenced the chance of their children’s attainment of certain elite positions (administrative, technocratic, or market) and whether these patterns have varied across three periods (1978–1992, 1993–2002, and 2003–2010). Using data obtained from the 2011 China Social Survey, we find that although parents’ advantageous status has a persistent effect on children’s status attainment, the reproduction of the state elite and market elite still follows two separate tracks: the children of cadres do not show significant advantage in the process of becoming entrepreneurs and managerial elites, and the children of entrepreneurial and managerial elites are less likely to join cadres. We also find that the effects of the reproduction model are still enhanced and shaped by state power in different periods. These findings demonstrate the important interplay between family background and contextual inequality and give a deeper understanding of the different trajectories of elites in contemporary China.

AbstractMarsupials exhibit unique biological features that provide fascinating insights into many aspects of mammalian development. These include their distinctive mode of reproduction, altricial stage at birth, and the associated heterochrony that is required for their crawl to the pouch and teat attachment. Marsupials are also an invaluable resource for mammalian comparative biology, forming a distinct lineage from the extant placental and egg-laying monotreme mammals. Despite their unique biology, marsupial resources are lagging behind those available for placentals. The fat-tailed dunnart (Sminthopsis crassicaudata) is a laboratory based marsupial model, with simple and robust husbandry requirements and a short reproductive cycle making it amenable to experimental manipulations. Here we present a detailed staging series for the fat-tailed dunnart, focusing on their accelerated development of the forelimbs and jaws. This study provides the first skeletal developmental series on S. crassicaudata and provides a fundamental resource for future studies exploring mammalian diversification, development and evolution.

In the process of sexual reproduction in angiosperms, making viable pollen grain to land on the surface of the receptive stigma of the same flower or other flower is the key process. Major factors like both biotic and abiotic play a crucial role in the process of making pollen to reach stigma during sexual mode of reproduction in angiosperms. In nature, some of the plants pollination take place without the support of any of the above said two factors, in some of the cases transfer of pollen aided by the biotic factors viz., insects, birds, animals etc., Particularly in the process of insect or bird aided pollen transfer, secretion of volatile compound in view of attracting pollinators have multiple role. In addition to above, flower with variety of colour also play a huge role in attraction of pollinators and its aid in timely occurrence of pollination. Further, due to climate change some of the pollinator population also become extinct, under that condition through evolutionary changes plant change their phenotypic expression by that way they attract other group of pollinator in the process of sexual mode of reproduction. Only the plant able to change their adaptation through the evolutionary process or through the event of mutation based on their requirement alone able to survive. This review discusses some of the important strategy adopted by the flowering plants in view of attraction of pollinators.

Abstract Background Apomixis, the asexual reproduction through seeds, occurs in over 40 plant families and avoids the hidden cost of sex. Apomictic plants are thought to have an advantage in sparse populations and when colonizing new areas but may have a disadvantage in changing environments because they propagate via fixed genotypes. In this study, we separated the influences of different genetic backgrounds (potentially reflecting local adaptation) from those of the mode of reproduction, i.e., sexual vs. apomictic, on nine fitness-related traits in Hieracium pilosella L. We aimed to test whether apomixis per se may provide a fitness advantage in different competitive environments in a common garden setting. Results To separate the effects of genetic background from those of reproductive mode, we generated five families of apomictic and sexual full siblings by crossing two paternal with four maternal parents. Under competition, apomictic plants showed reproductive assurance (probability of seeding, fertility), while offspring of sexual plants with the same genetic background had a higher germination rate. Sexual plants grew better (biomass) than apomictic plants in the presence of grass as a competitor but apomictic plants spread further vegetatively (maximum stolon length) when their competitors were sexual plants of the same species. Furthermore, genetic background as represented by the five full-sibling families influenced maximum stolon length, the number of seeds, and total fitness. Under competition with grass, genetic background influenced fecundity, the number of seeds, and germination rate. Conclusions Our results suggest that both the mode of reproduction as well as the genetic background affect the success of H. pilosella in competitive environments. Total fitness, the most relevant trait for adaptation, was only affected by the genetic background. However, we also show for the first time that apomixis per se has effects on fitness-related traits that are not confounded by—and thus independent of—the genetic background.

Steering has negative connotations nowadays in many discussions on governance, policy, politics and planning. The associations with the modernist state project linger on. At the same time, a rethinking of what is possible by means of policy and planning, what is possible through governance, which forms of change and which pursuits of common goods still make sense, in an era of cynicism about steering yet also high steering expectations, seems eminently useful. Between laissez faire and blue-print planning are many paths which can be walked. In this thematic issue, we highlight the value of evolutionary understandings of governance and of governance in society, in order to grasp which self-transformations of governance systems are more likely than others and which governance tools and ideas stand a better chance than others in a particular context. We pay particular attention to Evolutionary Governance Theory (EGT) as a perspective on governance which delineates steering options as stemming from a set of co-evolutions in governance. Understanding steering options requires, for EGT, path mapping of unique governance paths, as well as context mapping, the external contexts relevant for the mode of reproduction of the governance system in case. A rethinking of steering in governance, through the lens of EGT, can shed a light on governance for innovation, sustainability transitions, new forms of participation and self-organization. For EGT, co-evolutions and dependencies, not only limit but also shape possibilities of steering, per path and per domain of governance and policy.

Despite the long history of embryological studies of squamates, many groups of this huge clade have received only limited attention. One such understudied group is the anguimorphs, a clade comprising morphologically and ecologically very diverse lizards. We describe several stages of embryonic development of Anguis fragilis, a limbless, viviparous anguimorph. Interestingly, in several clutches we observe high morphological variation in characters traditionally important in classifying embryos into developmental stages. The causes of this variation remain unknown but environmental factors do not seem to be very important. Additionally, we describe the state of ossification in several perinatal specimens of A. fragilis. The cranial skeleton is relatively poorly ossified around the time of birth, with all of the bones constituting the braincase unfused. On the other hand, the vertebral column is well ossified, with the neurocentral sutures closed and the neural arches fused in all postatlantal vertebrae. Such an advanced state of ossification may be related to the greater importance of the vertebral column in locomotion in limbless species than in ones with fully-developed limbs. Numerous factors seem to affect the state of ossification at the time of hatching or birth in squamates, including phylogenetic position, mode of reproduction and, potentially, limblessness. However, data from a greater number of species are needed to reach firmer conclusions about the relative importance of these variables in certain clades.

Stream fish reproduction is still poorly studied in natural environments, especially in the Neotropical region. In this chapter, we recollect some characteristics of fish reproduction and some questions to guide current research, as: Does sexual dimorphism occur in the species? Which is the mode of reproduction? When and where does the species reproduce? Which environmental factors trigger reproductive events? When does the reproductive life begin? Which is the fecundity? Most of these questions can be answered when we have many specimens available, captured at different periods of the year, measured, weighed and dissected following appropriate protocols. Obtained data represent life history traits that allow to categorize the species in reproductive styles related to parental care and to determine their accordance to models of reproductive strategy associated with the predictability of environmental conditions. We highlight some aspects to be considered in current and future field and lab procedures, such as the recognition of sexual dimorphisms, the importance of naturalistic observation and lab procedures. We draw attention to the advances in studies on reproductive modalities in fish groups well represented in streams, such as inseminating characiforms and viviparous cyprinodontiforms. Finally, we highlight gaps, urgencies, and current perspectives for studies on the reproduction of stream fish, with emphasis on the need for basic studies of species biology, on the importance for building theoretical references and for the conservation of stream habitats in all Brazilian biomes.