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Modular Organisms (modular + organism)
Selected AbstractsWhat does the male function hypothesis claim?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2000Burd Paternal, rather than maternal, fitness consequences of reproductive traits are the lynchpin in many hypotheses about reproductive evolution in hermaphroditic angiosperms. These hypotheses often differ in their predictions, so that supporting or contradictory evidence for one hypothesis may not reflect similarly on another, even though both may be referred to as ,the male function hypothesis'. We provide graphical representations of four male function hypotheses from the recent literature in order to highlight their differences. We offer and explain two recommendations to reduce ambiguity in terminology: (1) male function hypotheses should address the evolution of excess flowers per se, rather than total flower number, which is usually highly plastic in modular organisms with open growth form; and (2) attention must be given to whole plant fitness, rather than fitness per flower or per inflorescence. In empirical studies, we recommend the use of path analysis to dissect the multiple pathways (through both male and female function) by which selection may act on excess flower number. [source] The use of taxonomic distinctness indices in assessing patterns of biodiversity in modular organismsMARINE ECOLOGY, Issue 2 2009Stanislao Bevilacqua Abstract Estimating diversity of modular organisms may be problematic due to actual difficulties in discriminating between ,individuals' and quantifying their abundances. Quantitative data, when available, are collected through methods that could preclude the application of classical diversity indices, making comparisons among studies difficult. Taxonomic distinctness indices, such as the ,Average Taxonomic Distinctness' (,+) and the ,Variation in Taxonomic Distinctness' (,+) may represent suitable tools in investigating diversity beyond the simple species number. The potential usefulness of such indices has been explored almost exclusively on unitary organisms, neglecting modular ones. In this study, we employed ,+ and ,+ to analyse patterns of diversity of epiphytic hydroid assemblages living on Cystoseira seaweeds at a hierarchy of spatial scales, along 800 km of rocky coast (SE Italy). ANOVA on species richness and ,+ showed no significant difference in sample diversity at the investigated spatial scales. In contrast, there were significant differences at the scale of 10s of km in ,+. Analyses based on simulations detected significant variations at all spatial scales in ,+. Such findings underline the potential of ,+ in highlighting relevant spatial scales of variation in patterns of hydroid diversity. Our results also suggest that the interplay between natural environmental variations and the complex ecological traits of modular organisms might affect taxonomic distinctness indices. We stress the need for further investigations focusing on modular organisms before any generalizations on the use of taxonomic relatedness measures in examining marine biodiversity can be made. [source] Performance benefits of growth-form plasticity in a clonal red seaweedBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2009KEYNE MONRO Phenotypic plasticity may be adaptive if the phenotype expressed in a focal environment performs better there relative to alternative phenotypes. Plasticity in morphology may particularly benefit modular organisms that must tolerate environmental change with limited mobility, yet this hypothesis has rarely been evaluated for the modular inhabitants of subtidal marine environments. We test the hypothesis for Asparagopsis armata, a clonal red seaweed whose growth-form plasticity across light environments is consistent with the concept of foraging behaviour in clonal plants. We manipulated the light intensity to obtain clonal replicates of compact, densely branched (,phalanx') phenotypes and elongate, sparsely branched (,guerrilla') phenotypes, which we reciprocally transplanted between inductive light environments to explore the performance consequences of a poor phenotype,environment match. Consistent with the hypothesis of adaptive plasticity, we found that performance (as relative growth rate) depended significantly on the interaction between growth form and environment. Each growth form performed better in its inductive environment than the alternative form, implying that this type of plasticity, thought to be adaptive for clonal plants, may also benefit photoautotrophs in marine environments. Given the prevalence and diversity of modular phyla in such systems, they offer a relatively unexplored opportunity to broaden our understanding of the evolutionary ecology of phenotypic plasticity. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 80,89. [source] | ||||||||||