970 resultados para Asexual Queen Succession
Resumo:
Recently shown in some termites, Asexual Queen Succession (AQS) is a reproductive strategy in which the primary queen is replaced by numerous parthenogenetically-produced neotenic queens that mate with the primary king. In contrast, the workforce and alate dispersers are produced sexually. If the primary king is replaced by a sexually-produced neotenic son, the matings between neotenic male and females beget asymmetries in the reproductive value of alates, promoting a female-biased alate sex-ratio. Cavitermes tuberosus (Termitidae: Termitinae) is a soil-feeding tropical species, which shows parthenogenetically-produced neotenics and an AQS syndrome. Our work aims to characterize the reproductive strategies in this species by determining (i) the developmental scheme, (ii) the genetic origin of sexuals, (iii) the level of genetic structure (analysis of 65 nests distributed in 14 sites) and (iv) the alate sex-ratio.Our results show that (i) neotenic females develop from the third or fourth nymphal instar; (ii) the majority of neotenic females (82%) are parthenogenetically-produced while only 2% of female alates are so; (iii) nests are differentiated within sites, indicating that the foundation of new nests mainly occurs by nuptial flights; (iv) numerical sex-ratio of alate-destined sexuals is balanced (SRN=0.509, IC95%=0.497-0.522) while investment sex-ratio is slightly female-biased (SRE=0.529, IC95%=0.517-0.542). Altogether, our results demonstrate AQS and its implications in C. tuberosus, and reveal particularities compared to other species in which AQS has been demonstrated: neotenic-headed nests are less frequent than primary-headed ones and neotenic females never become physogastric. AQS is found in various ecological contexts and seems phylogenetically more widespread than previously thought. This strategy shows some evolutionary advantages but these seem to differ depending on species.
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We report here development and characterization of 48 novel microsatellite markers for Ropalidia marginata, a tropical, primitively eusocial polistine wasp from peninsular India. Thirty-two microsatellites showed polymorphism in a wild population of R. marginata (N = 38) collected from Bangalore, India. These markers will facilitate answering some interesting questions in ecology and evolutionary biology of this wasp, such as population structure, serial polygyny, intra-colony genetic relatedness and the pattern of queen succession.
Resumo:
Ropalidia marginata is a primitively eusocial wasp widely distributed in peninsular India. Although solitary females found a small proportion of nests, the vast majority of new nests are founded by small groups of females. In suchmultiple foundress nests, a single dominant female functions as the queen and lays eggs, while the rest function as sterile workers and care for the queen's brood. Previous attempts to understand the evolution of social behaviour and altruism in this species have employed inclusive fitness theory (kin selection) as a guiding framework. Although inclusive fitness theory is quite successful in explaining the high propensity of the wasps to found nests in groups, several features of their social organization suggest that forces other than kin selection may also have played a significant role in the evolution of this species. These features include lowering of genetic relatedness owing to polyandry and serial polygyny, nest foundation by unrelated individuals, acceptance of young non-nest-mates, a combination of well-developed nest-mate recognition and lack of intra-colony kin recognition, a combination of meek and docile queens and a decentralized self-organized work force, long reproductive queues with cryptic heir designates and conflict-free queen succession, all resulting in extreme intra-colony cooperation and inter-colony conflict.
Resumo:
Recolonisation and succession in a multi-species tropical seagrass meadow was examined by creating gaps (50×50 cm) in the meadow and manipulating the supply of sexual and asexual propagules. Measurements of leaf shoot density and estimates of above-ground biomass were conducted monthly to measure recovery of gaps between September 1995 and November 1997. Measurements of the seeds stored in the sediment (seed bank) and horizontal rhizome growth of colonising species were also conducted to determine their role in the recovery process. Asexual colonisation through horizontal rhizome growth from the surrounding meadow was the main mechanism for colonisation of gaps created in the meadow. The seed bank played no role in recolonisation of cleared plots. Total shoot density and above-ground biomass (all species pooled) of cleared plots recovered asexually to the level of the undisturbed controls in 10 and 7 months, respectively. There was some sexual recruitment into cleared plots where asexual colonisation was prevented but seagrass abundance (shoot density and biomass) did not reach the level of unmanipulated controls. Seagrass species did not appear to form seed banks despite some species being capable of producing long-lived seeds. The species composition of cleared plots remained different to the undisturbed controls throughout the 26-month experiment. Syringodium isoetifolium was a rapid asexual coloniser of disturbed plots and remained at higher abundances than in the control treatments for the duration of the study. S. isoetifolium had the fastest horizontal rhizome growth of species asexually colonising cleared plots (6.9 mm day−1). Halophila ovalis was the most successful sexual coloniser but was displaced by asexually colonising species. H. ovalis was the only species observed to produce fruits during the study. Small disturbances in the meadow led to long-term (>2 years) changes in community composition. This study demonstrated that succession in tropical seagrass communities was not a deterministic process. Variations in recovery observed for different tropical seagrass communities highlighted the importance of understanding life history characteristics of species within individual communities to effectively predict their response to disturbance. A reproductive strategy involving clonal growth and production of long-lived, locally dispersed seeds is suggested which may provide an evolutionary advantage to plants growing in tropical environments subject to temporally unpredictable major disturbances such as cyclones
Resumo:
"Elizabeth [Strickland] contributed Elizabeth Stuart, queen of Bohemia, and Sophia, electress of Hanover."--Dict. nat. biog.
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One of the most critical issues for building innovation capacity in organisations is the acquisition and maintenance of knowledge. As knowledge is the basis of human capital, then the ability to attract, retain and engage talent is argued to be an important element of innovation. By attracting and retaining good staff, the organisation is retaining organisational knowledge which is necessary particularly for exploitation of current capabilities, but will also contribute to capacity for exploration for future innovation. This paper addresses the importance of retaining and developing staff as a critical issue for knowledge management and addresses the issue of retaining talent through effective succession management practices. The findings from an exploratory study into current practices in the Australian rail sector, provides further insight into the potentially critical issues for the effective use of succession management as a knowledge management and employee retention tool for building innovation capacity.
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People with intellectual disability are a relatively new but growing minority group within Australia's ageing population. Disability policies point to the equal right of people with disabilities to a quality of life similar to that of other citizens. Disability services are increasingly required to provide individualised and responsive services, irrespective of age, for people with lifelong disabilities. The present study explored the everyday lives of older people with intellectual disability in Victoria and Queensland, examining their experiences of using disability services and the ways in which services responded to their ageing. The aim of the study was to inform practice and service development for older people with intellectual disability. The findings suggest that services facilitate important social relationships with other service users and staff. Most older people had a sense of belonging and led busy but directionless lives in two disconnected worlds. Their lives were subject to significant external present-focused control. Yet, despite this, neither services nor family members took responsibility for ensuring their sense of continuity or supporting the development of plans about their future. The experiences described suggest an urgent need for, but significant challenges in the implementation of, holistic indivdualised planning similar to the UK concept of person-centred planning.
Resumo:
It is noted from observations of Compton (2009), Richards (2008), Taylor and Bennett (2002), and others that succession leadership planning and development fails to receive adequate attention in the corporate sector (see Byham 2002; Richards 2008; Wellins and Byham 2001). This paper acknowledges a marked paucity of systematic succession leadership development in education organisations. The need would seem to be compounded at a time when substantial attrition in the leadership ranks is expected over the next five years, reflecting widespread workforce demographics (Busine and Watt 2005; Jacobzone, Cambois, Chaplain, and Robine 1998; Taylor and Bennett 2002). The Lantern model has been developed in response to a perceived need to offer an integrated, systematic approach to organisational and succession leadership development. The model offers an organising framework for considering succession leadership development in a strategic, integrated way. The concept is based on organisational development and leadership literature which sees leadership development not as a series of 'tacked on' activities but as an organic 'whole of organisation' approach fostering the relevant knowledge, skills and understandings which support and 'grow' leaders as the organisation goes about its business. This paper explores how such an ideal might happen, and it suggests that pursuing such an ideal is timely. The leadership baton is set to shift at an accelerated rate in universities, as for organisations broadly, owing to age-related attrition. Moreover, given the increased complexity and demands of the leadership remit in the education leadership environment, it would seem particularly opportune to explore a framework concentrating on engendering a positive, connected organisational climate capable of growing strategic leadership strength from within. Eight core elements of the model, derived from the literature and practice research, are explored. The Lantern model purports to 'cover the bases' of succession leadership development, with particular reference to the education environment. The model is next described
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This paper intervenes in critical discussions about the representation of homosexuality. Rejecting the ‘manifest content’ of films, it turns to cultural history to map those public discourses which close down the ways in which films can be discussed. With relation to The Adventures of Priscilla, Queen of the Desert, it examines discussions of the film in Australian newspapers (both queer and mainstream) and finds that while there is disagreement about the interpretation to be made of the film, the terms within which those interpretations can be made are quite rigid. A matrix based on similarity, difference and value provides a series of positions and a vocabulary (transgression, assimilation, positive images and stereotypes) through which to make sense of this film. The article suggests that this matrix, and the idea that similarity and difference provide a suitable axis for making sense of homosexual identity, are problematic in discussing homosexual representation.
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Two main deformational phases are recognised in the Archaean Boorara Domain of the Kalgoorlie Terrane, Eastern Goldfields Superterrane, Yilgarn Craton, Western Australia, primarily involving southover- north thrust faulting that repeated and thickened the stratigraphy, followed by east northeast – west-southwest shortening that resulted in macroscale folding of the greenstone lithologies. The domain preserves mid-greenschist facies metamorphic grade, with an increase to lower amphibolite metamorphic grade towards the north of the region. As a result of the deformation and metamorphism, individual stratigraphic horizons are difficult to trace continuously throughout the entire domain. Volcanological and sedimentological textures and structures, primary lithological contacts, petrography and geochemistry have been used to correlate lithofacies between faultbounded structural blocks. The correlated stratigraphic sequence for the Boorara Domain comprises quartzo-feldspathic turbidite packages, overlain by high-Mg tholeiitic basalt (lower basalt), coherent and clastic dacite facies, intrusive and extrusive komatiite units, an overlying komatiitic basalt unit (upper basalt), and at the stratigraphic top of the sequence, volcaniclastic quartz-rich turbidites. Reconstruction of the stratigraphy and consideration of emplacement dynamics has allowed reconstruction of the emplacement history and setting of the preserved sequence. This involves a felsic, mafic and ultramafic magmatic system emplaced as high-level intrusions, with localised emergent volcanic centres, into a submarine basin in which active sedimentation was occurring.