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Clonal Species (clonal + species)
Selected AbstractsWhy does the unimodal species richness,productivity relationship not apply to woody species: a lack of clonality or a legacy of tropical evolutionary history?GLOBAL ECOLOGY, Issue 3 2008Lauri Laanisto ABSTRACT Aim, To study how differences in species richness patterns of woody and herbaceous plants may be influenced by ecological and evolutionary factors. Unimodal species richness,productivity relationships (SRPRs) have been of interest to ecologists since they were first described three decades ago for British herbaceous vegetation by J. P. Grime. The decrease in richness at high productivity may be due to competitive exclusion of subordinate species, or diverse factors related to evolution and dispersal. Unimodal SRPRs are most often reported for plants, but there are exceptions. For example, unimodal SRPRs are common in the temperate zone but not in the tropics. Similarly, woody species and forest communities in the Northern Hemisphere do not tend to show unimodal SRPRs. Location, Global. Methods, We used data from the literature to test whether a unimodal SRPR applies to woody species and forest communities on a global scale. We explored whether the shape of SRPRs may be related to the lack of clonality in woody species (which may prevent their being competitively superior), or the legacy of evolutionary history (most temperate woody species originate from tropical lineages, and due to niche conservatism they may still demonstrate ,tropical patterns'). We used case studies that reported the names of the dominant or most abundant species for productive sites. Results, Woody species were indeed less clonal than herbaceous species. Both clonality and the temperate evolutionary background of dominating species were associated with unimodality in SRPRs, with woodiness modifying the clonality effect. Main conclusions, The unimodal SRPR has been common in the ecological literature because most such studies originate from temperate herbaceous communities with many clonal species. Consequently, both evolutionary and ecological factors may influence species richness patterns. [source] Hybridization dynamics of invasive cattail (Typhaceae) stands in the Western Great Lakes Region of North America: a molecular analysisJOURNAL OF ECOLOGY, Issue 1 2010Steven E. Travis Summary 1.,By increasing vigour and broadening ecological tolerances, hybridization between native and introduced species may serve as a primary driver of invasiveness. 2.,Cattails (Typha, Typhaceae) are clonal wetland graminoids that are known to hybridize where anthropogenic influences have resulted in distributional overlap. 3.,In order to gauge the relative performance of hybrid vs. pure Typha, we characterized hybridization and clonal growth where native Typha latifolia and introduced Typha angustifolia occur together in the Western Great Lakes Region of North America. 4.,Based on microsatellite markers, we documented F1 hybrids as the most common class at five intensively sampled sites, constituting up to 90% of the genets and 99% of the ramets. Backcrosses to one or the other parent constituted 5,38% of the genets. Pure T. latifolia was rare and never constituted more than 12% of the genets. 5.,F1 hybrid genets achieved the highest mean ramet numbers at three sites, and were second in size only to T. angustifolia at two sites; however, these differences were not significant based on site-specific one-way anovas. 6.,F1 hybrids exhibited little height advantage over other Typha classes, although there was a general tendency for hybrids in relatively mixed stands to be among the tallest genets in shallow water, but among the shortest genets in deeper water. 7.,Native T. latifolia was found growing at the shallowest water depths at the only site where it was sufficiently abundant to be included in statistical comparisons. 8.,Synthesis. The role of hybridization in plant invasions can be difficult to confirm in the absence of molecular data, particularly for clonal species where the boundaries separating individuals are otherwise difficult to discern. Here, we used molecular markers to document the prevalence and performance of hybrid genets in five invasive Typha stands covering a broad area of the Western Great Lakes Region. We found an extremely high prevalence of F1 hybrids within mixed Typha stands. This, coupled with the typically larger sizes of hybrid genets, suggests that hybrids are capable of outperforming other Typha spp. and that hybridization has played an influential role in the North American cattail invasion. [source] Plant traits enabling survival in Mediterranean badlands in northeastern Spain suffering from soil erosionJOURNAL OF VEGETATION SCIENCE, Issue 4 2008Joaquín Guerrero-Campo Abstract Question: This study analysed the effect of severe soil erosion on species composition of plant communities by favouring species showing certain growth forms, root-sprouting and clonal growth abilities. Location: The study area was located between the middle Ebro Valley and the Pre-Pyrenees (northeastern Spain). Methods: Root-sprouting and shoot-rooting abilities, clonal reproduction and growth form were assessed for the 123 most common plant species from eroded lands in the study area. We obtained 260 vegetation relevés in three different substrata (gypsum outcrops, Miocene clays and Eocene marls) on areas with different degrees of soil erosion. The frequency of every plant trait in each relevé was estimated according to species presence. The effect of soil erosion on the frequency of plant attributes was assessed by correlation analyses. Results: Bipolar, non-clonal plants and annual species decreased their frequency with increasing soil erosion in the three substrata analyzed, whereas root-sprouters and woody plants (mostly sub-shrubs) increased their frequency in most of the substrata analysed. Conclusions: Woody sub-shrubs, root-sprouters and clonal species are favoured in eroded lands in NE Spain. Bipolar species and annual plants might not be plastic enough to survive the high stress and frequent disturbances prevailing in such eroded areas. [source] Plant functional group composition and large-scale species richness in European agricultural landscapesJOURNAL OF VEGETATION SCIENCE, Issue 1 2008Jaan Liira Abstract Question: Which are the plant functional groups responding most clearly to agricultural disturbances? Which are the relative roles of habitat availability, landscape configuration and agricultural land use intensity in affecting the functional composition and diversity of vascular plants in agricultural landscapes? Location: 25 agricultural landscape areas in seven European countries. Methods: We examined the plant species richness and abundance in 4 km × 4 km landscape study sites. The plant functional group classification was derived from the BIOLFLOR database. Factorial decomposition of functional groups was applied. Results: Natural habitat availability and low land use intensity supported the abundance and richness of perennials, sedges, pteridophytes and high nature quality indicator species. The abundance of clonal species, C and S strategists was also correlated with habitat area. An increasing density of field edges explained a decrease in richness of high nature quality species and an increase in richness of annual graminoids. Intensive agriculture enhanced the richness of annuals and low nature quality species. Conclusions: Habitat patch availability and habitat quality are the main drivers of functional group composition and plant species richness in European agricultural landscapes. Linear elements do not compensate for the loss of habitats, as they mostly support disturbance tolerant generalist species. In order to conserve vascular plant species diversity in agricultural landscapes, the protection and enlargement of existing patches of (semi-) natural habitats appears to be more effective than relying on the rescue effect of linear elements. This should be done in combination with appropriate agricultural management techniques to limit the effect of agrochemicals to the fields. [source] A measure for spatial heterogeneity of a grassland vegetation based on the beta-binomial distributionJOURNAL OF VEGETATION SCIENCE, Issue 5 2000Masae Shiyomi Abstract. A method is proposed to estimate the frequency and the spatial heterogeneity of occurrence of individual plant species composing the community of a grassland or a plant community with a short height. The measure is based on the beta-binomial distribution. The weighted average heterogeneity of all the species composing a community provides a measure of community-level heterogeneity determining the spatial intricateness of community composition of existing species. As an example to illustrate the method, a sown grassland with grazing cows was analysed, on 102 quadrats of 50 cm × 50 cm, each of which divided into four small quadrats of 25 cm × 25 cm. The frequency of occurrence for all the species was recorded in each small quadrat. Good fits to the beta-binomial series for most species of the community were obtained. These results indicate that (1) each species is distributed heterogeneously with respective spatial patterns, (2) the degree of heterogeneity is different from species to species, and (3) the beta-binomial distribution can be applied for grassland communities. In most of the observed species spatial heterogeneity is often characterized by species-specific propagating traits: seed-propagating plant species exhibited a low heterogeneity/random pattern while clonal species exhibited a high heterogeneity/aggregated pattern. This measure can be applied to field surveys and to the estimation of community parameters for grassland diagnosis. [source] Major histocompatibility complex variability in the clonal Amazon molly, Poecilia formosa: is copy number less important than genotype?MOLECULAR ECOLOGY, Issue 6 2009K. P. LAMPERT Abstract The evolution of sex is still a major unsolved puzzle in biology. One of the most promising theoretical models to answer this question is the Red Queen hypothesis. The Red Queen hypothesis proposes a fast adaptation of pathogens to common genotypes and therefore a negative frequency-dependent selection against common genotypes. Clonal organisms should be especially endangered when co-occurring with closely related sexual species. In this context, major histocompatibility (MHC) genes have been discussed to be auspicious candidates that could provide the genetic basis on which selection for immune competence could act. In this study, we investigated MHC variability in a clonal teleost fish: the Amazon molly, Poecilia formosa. The Amazon molly is an ideal candidate to test the Red Queen hypothesis as it is a clonal species but co-occurs with a closely related sexual species and should therefore be especially susceptible to pathogen infection. We found that allele numbers did in general not differ between sexual and clonal ,species' but that genotypic variability is reduced in the clonally reproducing fish, especially in the polyploids. We conclude that in clonal organisms, genotype frequency might be more important for immune competence than MHC allele number. Amazon mollies and their co-occurring parental species clearly fulfil a prerequisite of the Red Queen hypothesis and should therefore provide an ideal system to experimentally test this basic principle probably underlying the evolution of sex. [source] | ||||||||||