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Group Relationships (group + relationships)
Selected AbstractsAnatomy and systematics of the minute syrnolopsine gastropods from Lake Tanganyika (Caenogastropoda, Cerithioidea, Paludomidae)ACTA ZOOLOGICA, Issue 4 2008Ellen E. Strong Abstract The minute syrnolopsine gastropods endemic to Lake Tanganyika have been allied to a number of freshwater, marine and terrestrial groups as a consequence of superficial conchological similarity. Although early anatomical studies confirmed the cerithioid organization of this clade, their close relationship to other lake species was not consistently recognized. In several recent cladistic analyses based on molecular data, the higher taxonomic placement and sister group relationships of syrnolopsines have been unstable. The present analysis confirms that syrnolopsines possess a spermatophore-forming organ , a synapomorphy of the Paludomidae , corroborating their placement in this family. Consistent with the molecular data, syrnolopsine monophyly is supported by two characters that occur exclusively in this group (salivary gland ducts that bypass the nerve ring and a linear albumen gland). Several characters in Martelia tanganyicensis, the most diminutive syrnolopsine , are only evident in the smallest lake species thus far investigated (Bridouxia, Stormsia) namely reduction of ctenidial leaflets, sorting area, intestine length and number of statoconia. These features are interpreted as being correlated with reduction in size. Nevertheless, close examination reveals differences in detail that allow more refined hypotheses of homology and are consistent with their independent origin. [source] Framework of Joint Venture Development: Theory-Building Through Qualitative ResearchJOURNAL OF MANAGEMENT STUDIES, Issue 5 2000Bettina Büchel Based on an inductive, longitudinal case study, this paper proposes a framework of joint venture development. The framework is comprised of three overlapping stages of development: formation, adjustment, and evaluation with shorter, cyclical periods. These periods, labeled phases, can be described in terms of alternations between divergence and convergence of two types of group relationships: intra-joint venture relations and boundary group relations. Propositions lay out the development from the formation to the evaluation stage explaining the cyclical nature of divergence and convergence. The framework advances the existing literature on joint venture development by pointing out both micro- and macro-level driving forces and the conditions under which certain developmental patterns emerge. [source] Evaluation of the mentor,mentee relationship in an occupational therapy mentorship programmeOCCUPATIONAL THERAPY INTERNATIONAL, Issue 2 2004MClSc(OT)OT Reg (Ont) Occupational Therapist, Tracy Milner BA (Honours Kinesiology) Abstract Mentor group relationships in an occupational therapy university curriculum were investigated. In phase I, mentors (n = 23) and mentees (n = 124) were surveyed over a four year period. In phase II, 14 mentees from the same time period were surveyed after graduation. It was found that mentors and mentees surveyed agreed that their mentor group leader displayed more mentoring (i.e. ongoing partnership for guidance and support) than coaching (i.e. short-term relationship for providing feedback on areas requiring change) characteristics, and most agreed that, post-graduation, their mentor group leader had been a mentor to them. Mentees viewed their mentors predominantly as a role model or counsellor and emphasized knowledge, experience, guidance, and support as desirable attributes of a mentor. Contact with mentors for resources, support, or job-related purposes continued after graduation for more than half of mentees. Some mentees reported that peer mentoring had also occurred. Limitations of the study include the small sample size in Phase II and some aspects of survey design. Future areas of research identified include studying the development of the relationship over time (i.e. pre-, mid-way, and post-programme), comparing relationships between mentors and mentees who have similar versus dissimilar expectations for the programme, further examining peer mentoring or group relationships, and continuing post-graduation surveys with a larger sample size for increased reliability. Copyright © 2004 Whurr Publishers Ltd. [source] ,After Africa': the evolutionary history and systematics of the genus Charaxes Ochsenheimer (Lepidoptera: Nymphalidae) in the Indo-Pacific regionBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010CHRIS J. MÜLLER The predominantly Afrotropical genus Charaxes is represented by 31 known species outside of Africa (excluding subgenus Polyura Billberg). We explored the biogeographic history of the genus using every known non-African species, with several African species as outgroup taxa. A phylogenetic hypothesis is proposed, based on molecular characters of the mitochondrial genes cytochrome oxidase subunit I (COI) and NADH dehydrogenase 5 (ND5), and the nuclear wingless gene. Phylogenetic analyses based on maximum parsimony and Bayesian inference of the combined dataset implies that the Indo-Pacific Charaxes form a monophyletic assemblage, with the exception of Charaxes solon Fabricius. Eight major lineages are recognized in the Indo-Pacific, here designated the solon (+African), elwesi, harmodius, amycus, mars, eurialus, latona, nitebis, and bernardus clades. Species group relationships are concordant with morphology and, based on the phylogeny, we present the first systematic appraisal and classification of all non-African species. A biogeographical analysis reveals that, after the genus originated in Africa, the evolutionary history of Charaxes in the Indo-Pacific, in particular Wallacea, may be correlated with the inferred geological and climatic history of the region. We propose that Wallacea was the area of origin of all Charaxes (excluding C. solon) occurring to the east of Wallace's [1863] Line. The earliest Indo-Pacific lineages appear to have diverged subsequent to the initial fragmentation of a palaeo-continent approximately 13 million years ago. Further diversification in Indo-Pacific Charaxes appears primarily related to climatic changes during the Pliocene and possibly as recently as the Pleistocene. Although both dispersal and vicariance have played important roles in the evolution of the genus within the region, the latter has been particularly responsible for diversification of Charaxes in Wallacea. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 457,481. [source] A global phylogeny of apple snails: Gondwanan origin, generic relationships, and the influence of outgroup choice (Caenogastropoda: Ampullariidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009KENNETH A. HAYES Apple snails (Ampullariidae) are a diverse family of pantropical freshwater snails and an important evolutionary link to the common ancestor of the largest group of living gastropods, the Caenogastropoda. A clear understanding of relationships within the Ampullariidae, and identification of their sister taxon, is therefore important for interpreting gastropod evolution in general. Unfortunately, the overall pattern has been clouded by confused systematics within the family and equivocal results regarding the family's sister group relationships. To clarify the relationships among ampullariid genera and to evaluate the influence of including or excluding possible sister taxa, we used data from five genes, three nuclear and two mitochondrial, from representatives of all nine extant ampullariid genera, and species of Viviparidae, Cyclophoridae, and Campanilidae, to reconstruct the phylogeny of apple snails, and determine their affinities to these possible sister groups. The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins. All four Old World genera, Afropomus, Saulea, Pila, and Lanistes, were recovered as monophyletic, but only Asolene, Felipponea, and Pomella were monophyletic among the five New World genera, with Marisa paraphyletic and Pomacea polyphyletic. Estimates of divergence times among New World taxa suggest that diversification began shortly after the separation of Africa and South America and has probably been influenced by hydrogeological events over the last 90 Myr. The sister group of the Ampullariidae remains unresolved, but analyses omitting certain outgroup taxa suggest the need for dense taxonomic sampling to increase phylogenetic accuracy within the ingroup. The results obtained also indicate that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98, 61,76. [source] | ||||||||||