scholarly journals Strong whole life-cycle inbreeding depression in Daphnia magna enhanced by partial asexuality

2020 ◽  
Author(s):  
Valentina G. Tambovtseva ◽  
Anton A. Zharov ◽  
Christoph R. Haag ◽  
Yan R. Galimov
Keyword(s):  
Life Cycle ◽  
Daphnia Magna ◽  
Inbreeding Depression ◽  
Experimental Studies ◽  
Life Cycles ◽  
Mating Strategies ◽  
Breeding Systems ◽  
Similar Species ◽  
Entire Life ◽  
Whole Life Cycle

ABSTRACTInbreeding depression is a key factor in the evolution of mating strategies and breeding systems across the eukaryotic tree of life. Yet its potential impact in partially asexual species has only received little attention. We studied inbreeding depression in the cyclical parthenogen Daphnia magna by following mixtures of inbred and outbred genotypes from an early embryonic stage through hatching to adulthood and then across several asexual generations. We found that, across asexual generations, the frequency of inbred genotypes strongly and constantly decreased, until the experimental populations were almost entirely made up of outbred genotypes. The resulting estimate of inbreeding depression across the entire life cycle was almost 100 %, much higher than previous estimates for this and other similar species. Our results illustrate that the magnitude of inbreeding depression may be severely underestimated in studies that use fitness components or proxies instead of compound fitness estimates across the entire life, as well as in experimental studies with substantial pre-experimental mortality. More generally, our results suggest that inbreeding depression may play an important role in the evolution of partially asexual life cycles because clonal reproduction maintains inbreeding levels, and hence the negative effects of inbreeding accumulate across subsequent asexual generations.

scholarly journals Sexual morph specialisation in a trioecious nematode balances opposing selective forces.

2021 ◽  
Author(s):  
Sally Adams ◽  
Prachi Pathak ◽  
Maike Kittelmann ◽  
Alun R.C. Jones ◽  
Eamonn B Mallon ◽  
...  
Keyword(s):  
Life Cycle ◽  
Inbreeding Depression ◽  
Mating Strategies ◽  
Breeding Systems ◽  
Energetic Cost ◽  
Mate Finding ◽  
Sexual Morph ◽  
Selective Forces ◽  
Gene Expression Studies ◽  
Stable Maintenance

The coexistence of different mating strategies, whereby a species can reproduce both by selfing and outcrossing, is an evolutionary enigma that has long intrigued biologists (Darwin, 1877). Theory predicts only two stable mating states : outcrossing with strong inbreeding depression or selfing with weak inbreeding depression. As these two mating strategies are subject to opposing selective forces, mixed breeding systems are thought to be a rare transitory state, yet they have been found to persist even after multiple speciation events. We hypothesise that if each mating strategy plays a distinctive role during the species life history, opposing selective pressures could be balanced, permitting the stable co-existence of selfing and outcrossing sexual morphs. In this scenario, we would expect each sexual morph to be specialised in their respective roles. Here we show, using a combination of behavioural, physiological and gene expression studies, that the selfing (hermaphrodite) and outcrossing (female) sexual morphs of the trioecious nematode Auanema freiburgensis have distinct adaptations optimised for their different roles during the life cycle. A. freiburgensis hermaphrodites are produced under stressful conditions, are specialised for dispersal to new habitat patches and exhibit metabolic and intestinal changes that enable them to meet the energetic cost of dispersal and reproduction. In contrast, A. freiburgensis females are produced in favourable conditions, facilitate rapid population growth and compensate for the lack of reproductive assurance by reallocating resources from intestinal development to robust mate-finding behaviour. The specialisation of each mating system for their role in the life cycle could balance opposing selective forces allowing the stable maintenance of both outcrossing and selfing mating systems in A. freiburgensis.

Detection of a new Clytia species (Cnidaria: Hydrozoa: Campanulariidae) with DNA barcoding and life cycle analyses

2013 ◽  
Vol 93 (8) ◽  
pp. 2075-2088 ◽  
Author(s):  
Konglin Zhou ◽  
Lianming Zheng ◽  
Jinru He ◽  
Yuanshao Lin ◽  
Wenqing Cao ◽  
...  
Keyword(s):  
Life Cycle ◽  
Dna Barcoding ◽  
Ribosomal Rna ◽  
Coastal Waters ◽  
Large Subunit ◽  
Life Cycles ◽  
Complex Life Cycles ◽  
Distinct Lineage ◽  
Whole Life Cycle ◽  
Medusa Stage

The genus Clytia is distributed worldwide, but most accepted species in this genus have been examined either only at the hydroid or medusa stage. The challenge in identifying Clytia species reflects their complex life cycles and phenotypic plasticity. In this study, molecular and morphological investigations of Clytia specimens from the coastal waters of China revealed an as yet unreported species, designated C. xiamenensis sp. nov., that was considered as conspecific to two nearly cosmopolitan species, C. hemisphaerica and C. gracilis. DNA barcoding based on partial mitochondrial cytochrome c oxidase subunit I (COI) and large subunit ribosomal RNA gene (16S) confirmed the highly distinct lineage of C. xiamenensis sp. nov. These results were corroborated by the detailed observations of its mature medusae and its colonies, which showed that C. xiamenensis sp. nov. was morphologically distinct from other species of Clytia. Thus, based on our findings, the nearly cosmopolitan distribution attributed to some species of Clytia might rather be due to the misidentification, and it is necessary to elucidate their whole life cycle in order to establish the systematic validity of all species within the genus Clytia.

Study on Life Cycle Assessment of Servo Press With Comparison to Flywheel Press

2013 ◽  
Author(s):  
Suiran Yu ◽  
Yu Liu ◽  
Lu Li ◽  
Qingjin Peng
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Life Cycles ◽  
Planning And Design ◽  
Servo Press ◽  
Life Cycle Stages ◽  
Tremendous Amount ◽  
Efficient Machine ◽  
Whole Life Cycle ◽  
Two Machines

Heavy duty machines consume a tremendous amount of energy during their life cycle. Therefore, designing an energy efficient machine is of great importance. This paper presents a method for the comparative life cycle assessment (LCA) of two different types of press machines: servo press and flywheel press to understand quantitatively the environmental emissions during their life cycles. To make a fair comparison of the two machines, the same amount of production is used as the basis for comparison. Assessment scopes and boundaries are defined first, then detailed product structures and manufacturing processes are investigated. After data collection from visiting enterprises, related project reports, academic papers, and commercial software databases, analysis of the life cycle inventory is performed. Comparative inventory tables for each life cycle stages and whole life cycle are presented. The results of the study can be used for decision making during the product purchase, planning and design process.

scholarly journals Evaluation of the Distribution of Shrimp Species Found in Southern Benin Through the Lake Nokoué-ocean Complex

2021 ◽  
Author(s):  
Sèlomè Wilfried Sintondji ◽  
Amoussou Sylvain Gozingan ◽  
Zacharie Sohou ◽  
Matthieu Taymans ◽  
Katrijn Baetens ◽  
...  
Keyword(s):  
Life Cycle ◽  
Literature Review ◽  
Temporal Dynamics ◽  
Life Cycles ◽  
The European Union ◽  
Entire Life ◽  
Entire Life Cycle ◽  
Favorable Environment ◽  
Spatio Temporal ◽  
Southern Benin

Abstract BackgroundThe export of shrimp to the European Union was one of the mainstays of the Beninese economy. It is an income-generating activity for the populations living along lake Nokoué. The lack of a fisheries management strategy has caused a drastic decline in shrimp production in lake Nokoué since 2003. To remedy this problem, it is necessary to hypothesize on their spatio-temporal dynamics in the lake Nokoué-Cotonou channel complex. This is investigated by combining a literature review on their life cycles and habitat suitability with spatio-temporal evolution of salinity obtained from in-situ observations.ResultsThe literature review recognizes the presence in southern Benin of species of the genus Macrobrachium, Atya and Desmocaris (seven, two and one respectively) and five species of marine shrimps belonging to three genera: the genus Penaeus, the genus Holthuispenaeopsis and the genus Parapenaeus. From information on the ecology and physical environment it is shown that adults of the species of the genus Macrobrachium and genus Atya have a favorable environment in lake Nokoué from August to November, their larvae must remain in the lake from December to June to ensure their survival. The species of the genus Desmocaris, which carry out their entire life cycle in fresh water, can stay in lake Nokoué from August to November. The species of the genus Penaeus can find a favorable environment in lake Nokoué from December to June but their larvae can only survive in the sea. Finally, the species of the genus Holthuispenaeopsis and Parapenaeus spend their entire life cycle at sea.ConclusionsThis work allows understanding contrasted life cycles of shrimp’s genera Macrobrachium and Atya compared to Penaeus in a complex ecosystem characterized by strong saline variation. This research allows to predict the presence or absence of shrimp’s genera Macrobrachium, Atya, Desmocaris and Penaeus in a lake system, on the basis of salinity distribution, for a sustainable management of their exploitation.

Experimental Studies of the Crack Formation Moment of Reinforced Concrete Beams

2019 ◽  
Vol 968 ◽  
pp. 248-257
Author(s):  
Svetlana Romanenko ◽  
Yanina Andriievska
Keyword(s):  
Life Cycle ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Crack Formation ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Reinforced Concrete Beams ◽  
Main Task ◽  
Entire Life ◽  
Entire Life Cycle

The main task of construction is providing buildings with the property to remain operable throughout the entire life cycle. The level of bearing capacity, both of individual structures and buildings as a whole, depends on many factors.

Cryptic species, life cycles, and the phylogeny of Clytia (Cnidaria: Hydrozoa: Campanulariidae)

Zootaxa ◽  
2011 ◽  
Vol 2980 (1) ◽  
pp. 23 ◽  
Author(s):  
ALBERTO LINDNER ◽  
ANNETTE F. GOVINDARAJAN ◽  
ALVARO E. MIGOTTO
Keyword(s):  
Life Cycle ◽  
North Atlantic ◽  
Virgin Islands ◽  
Life Cycles ◽  
Southeastern Brazil ◽  
Similar Species ◽  
Western Atlantic ◽  
Morphological Studies ◽  
Coastal Marine ◽  
Multigene Phylogenetic Analysis

Medusae and polyps of Clytia are abundantly found in coastal marine environments and one species in the genus—Clytia hemisphaerica (Linnaeus, 1767)—has become an important experimental model. Yet, only 10 species in the genus have had their life cycle investigated. Most species of Clytia are also poorly described, and detailed life cycle and morphological studies are needed for accurate species-level identifications. Here, we investigated the life cycle of Clytia elsaeoswaldae Stechow, 1914, a species described for the tropical western Atlantic and subsequently considered conspecific to the nearly-cosmopolitan species Clytia gracilis (Sars, 1850) and Clytia hemisphaerica, originally described for the temperate North Atlantic. Based on observations of mature medusae and multiple colonies from southeastern Brazil and the U. S. Virgin Islands (type locality), our results show that C. elsaeoswaldae is morphologically distinct from C. gracilis and C. hemisphaerica. The morphological results are corroborated by a multigene phylogenetic analysis of the genus Clytia, which shows that C. gracilis-like species form a polyphyletic group of several species. These results suggest that the nearly-cosmopolitan distribution attributed to some species of Clytia may be due to the non-recognition of morphologically similar species with more restricted ranges.

scholarly journals Digital twins for managing railway maintenance and resilience

2021 ◽  
Vol 1 ◽  
pp. 91
Author(s):  
Sakdirat Kaewunruen ◽  
Jessada Sresakoolchai ◽  
Yi-hsuan Lin
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Life Cycles ◽  
Optimal Time ◽  
Transit System ◽  
Digital Twin ◽  
Operation And Maintenance ◽  
Railway Maintenance ◽  
Whole Life Cycle

Background: To improve railway construction and maintenance, a novel digital twin that helps stakeholders visualize, share data, and monitor the progress and the condition during services is required. Building Information Modelling (BIM) is a digitalization tool, which adopts an interoperable concept that benefits the whole life-cycle assessment (LCA) of the project. BIM’s applications create higher performance on cost efficiency and optimal time schedule, helping to reduce any unexpected consumption and waste over the life cycle of the infrastructure. Methods: The digital twin will be developed using BIM embedded by the lifecycle analysis method. A case study based on Taipei Metro (TM) has been conducted to enhance the performance in operation and maintenance. Life cycles of TM will be assessed and complied with ISO14064. Operation and maintenance activities will be determined from official records provided by TM. Material flows, stocks, and potential risks in the LCA are analyzed using BIM quantification embedded by risk data layer obtained from TM. Greenhouse emission, cost consumption and expenditure will be considered for integration into the BIM. Results: BIM demonstrated strong potential to enable a digital twin for managing railway maintenance and resilience. Based on the case study, a key challenge for BIM in Taiwan is the lack of insights, essential data, and construction standards, and thus the practical adoption of BIM for railway maintenance and resilience management is still in the design phase. Conclusions: This study exhibits a practical paradigm of the digital twin for railway maintenance and resilience improvement. It will assist all stakeholders to engage in the design, construction, and maintenance enhancing the reduction in life cycle cost, energy consumption and carbon footprint. New insight based on the Taipei Mass Rapid Transit system is highly valuable for railway industry globally by increasing the lifecycle sustainability and improving resilience of railway systems.

Floral traits, pollination ecology and breeding system of three Clematis species (Ranunculaceae) in Yunnan province, southwestern China

2010 ◽  
Vol 58 (2) ◽  
pp. 115 ◽  
Author(s):  
Nan Jiang ◽  
Wen-Bin Yu ◽  
Hong-Zhe Li ◽  
Kai-Yun Guan
Keyword(s):  
Inbreeding Depression ◽  
Breeding System ◽  
Pollen Limitation ◽  
Mating Strategies ◽  
Breeding Systems ◽  
Floral Traits ◽  
Pollination Syndrome ◽  
Self Pollination ◽  
Hand Pollination ◽  
Integrative Study

Flowers of Clematis display showy corollas and diversified shapes. This diversity motivates study of adaptive evolution of flower–pollinator interactions and the functional association between floral traits and plant mating strategies. An integrative study was undertaken, which focused on pollination and reproductive biology of three species representing all three floral types of Clematis. Floral traits were measured, and pollinator assemblages were observed in the field. Bagging, hand-pollination and removal treatments were used to examine breeding systems. The inbreeding depression and pollen limitation were estimated by fruit-set and seed production obtained from pollination treatments. Their floral traits are distinctly different, but are highly associated with pollination syndrome and breeding system. Among them, Clematis akebioides and C. rehderiana may be facultative autogamy (the former was delayed selfing, and the later competing selfing), and C. chrysocoma may be nearly obligate outcrossing. These conclusions are reflected in their stamen-pistil ratios. The levels of inbreeding depression are negatively associated with autonomous self-pollination. Evolution of self-pollination in C. akebioides and C. rehderiana, and pollen limitation in reproduction of the three Clematis species are discussed. This present study, integrating with previous results, will help us to comprehensively recognise and understand the pollination system and reproductive characteristics of Clematis.

MERGERS AND ACQUISITIONS AND THEIR CORRELATION WITH THE LIFE CYCLES OF MEMBER COMPANIES ON THE EXAMPLE OF THE RUSSIAN MARKET 2017–2019

2020 ◽  
Vol 1 (10) ◽  
pp. 26-35
Author(s):  
E. A. SHUBINA ◽  
◽  
Yu. A. KOMAROVSKY ◽  
A. V. MERKUSHEV ◽  
◽  
...  
Keyword(s):  
Life Cycle ◽  
Mergers And Acquisitions ◽  
Life Cycles ◽  
Russian Market

The article is devoted to the study of the largest mergers and acquisitions (M&A, “Mergers & Acquisitions”) in Russia for 2017–2019. (the acquired block of shares is not less than 99%). The concept of life cycles of organizations and theoretical aspects of mergers and acquisitions are described. The stages of the life cycle of the merged and reorganized companies, the goals of mergers and acquisitions, depending on the stages of the life cycle are analyzed.

Sign in / Sign up

Export Citation Format

Share Document