Intraspecific Variation on Early Growth of Neolamarckia Cadamba Miq. in Provenance-progeny Tests in West Java Province, Indonesia

Genetic parameters on early growth of Neolamarckia cadamba, an indigenous species with potential as a source of wood timber, were estimated in open-pollinated provenance-progeny tests at two sites in West Java Province, Indonesia. The experiment was conducted using randomized complete block design with 12 provenances, 105 families and 5 replications of 4-tree row plots. Total height and root collar diameter were measured at the age of 18 months growth. Significant differences among the provenances and families within provenances were observed for height and collar diameter at all sites, except for the collar diameter of among provenances at Parungpanjang site. In general, Garut (GSJ) provenance performed better growth at the two sites than Kualakencana (KKP) and Nusa Kambangan (NKJ) provenances. The evaluation of component of variance at the two sites showed that the provenance effects (ranging from 0.5 to 1.7%) contributed more to total variance than family within provenance effects(ranging from 0.4 to 0.6%). Genetic correlations between height and collar diameter were weak to moderate. Heritability was low for all traits at Limbangan, while at Parungpanjang, the heritability was moderate. Estimation of genetic gain for height and diameter by proportional selected family 0.30 was 0.13 and 0.18 for Limbangan and 0.31 and 0.16 for Parungpanjang. Heritability measurement should be sustained to reach stable value. Stable heritability combined with selection of family and selection within family will improve genetic gain

Ecological Opportunity In Adaptive Radiation Of Galapagos Endemic Land Snails

The classic evolutionary hypothesis of ecological opportunity proposes that both heterogeneity of resources and freedom from enemies promote phenotypic divergence as a response to increased niche availability. Although phenotypic divergence and speciation have often been inferred to be the primary consequences of the release from competition or predation that accompanies a shift to a new adaptive zone, increased phenotypic variation within species is expected to represent the first stage resulting from such a shift. Using measures of intraspecific morphological variation of 30 species of Galapagos endemic land snails in a phylogenetically controlled framework, we show that the number of local congeners and the number of local plant species are associated with lower and higher intraspecific phenotypic variation, respectively. In this clade, ecological opportunity thus explicitly links the role of competition from congeners and the heterogeneity of resources to the extent of intraspecific phenotypic divergence as adaptive radiation proceeds.Integrative Biolog

Intraspecific trait variation and coordination: Root and leaf economics spectra in coffee across environmental gradients

Hypotheses on the existence of a universal “Root Economics Spectrum” (RES) have received arguably the least attention of all trait spectra, despite the key role root trait variation plays in resource acquisition potential. There is growing interest in quantifying intraspecific trait variation (ITV) in plants, but there are few studies evaluating (i) the existence of an intraspecific RES within a plant species, or (ii) how a RES may be coordinated with other trait spectra within species, such as a leaf economics spectrum (LES). Using Coffea arabica (Rubiaceae) as a model species, we measured seven morphological and chemical traits of intact lateral roots, which were paired with information on four key LES traits. Field collections were completed across four nested levels of biological organization. The intraspecific trait coefficient of variation (cv) ranged from 25 to 87% with root diameter and specific root tip density showing the lowest and highest cv, respectively. Between 27 and 68% of root ITV was explained by site identity alone for five of the seven traits measured. A single principal component explained 56.2% of root trait covariation, with plants falling along a RES from resource acquiring to conserving traits. Multiple factor analysis revealed significant orthogonal relationships between root and leaf spectra. RES traits were strongly orthogonal with respect to LES traits, suggesting these traits vary independently from one another in response to environmental cues. This study provides among the first evidence that plants from the same species differentiate from one another along an intraspecific RES. We find that in one of the world's most widely cultivated crops, an intraspecific RES is orthogonal to an intraspecific LES, indicating that above and belowground responses of plants to managed (or natural) environmental gradients are likely to occur independently from one another. (Résumé d'auteur

Intraspecific variability modulates interspecific variability in animal organismal stoichiometry.

Interspecific differences in organismal stoichiometry (OS) have been documented in a wide range of animal taxa and are of significant interest for understanding evolutionary patterns in OS. In contrast, intraspecific variation in animal OS has generally been treated as analytical noise or random variation, even though available data suggest intraspecific variability in OS is widespread. Here, we assess how intraspecific variation in OS affects inferences about interspecific OS differences using two co-occurring Neotropical fishes: Poecilia reticulata and Rivulus hartii. A wide range of OS has been observed within both species and has been attributed to environmental differences among stream systems. We assess the contributions of species identity, stream system, and the interactions between stream and species to variability in N:P, C:P, and C:N. Because predation pressure can impact the foraging ecology and life-history traits of fishes, we compare predictors of OS between communities that include predators, and communities where predators are absent. We find that species identity is the strongest predictor of N:P, while stream or the interaction of stream and species contribute more to the overall variation in C:P and C:N. Interspecific differences in N:P, C:P, and C:N are therefore not consistent among streams. The relative contribution of stream or species to OS qualitatively changes between the two predation communities, but these differences do not have appreciable effects in interspecific patterns. We conclude that although species identity is a significant predictor of OS, intraspecific OS is sometimes sufficient to overwhelm or obfuscate interspecific differences in OS

High species turnover and low intraspecific trait variation in endemic and non-endemic plant species assemblages on an oceanic island

Questions Both species turnover and intraspecific trait variation can affect plant assemblage dynamics along environmental gradients. Here, we asked how community assemblage patterns in relation to species turnover and intraspecific variation differ between endemic and non-endemic species. We hypothesized that endemic species show lower intraspecific variation than non-endemic species because they tend to have high rates of in situ speciation, whereas non-endemic species are expected to have a larger gene pool and higher phenotypic plasticity. Location La Palma, Canary Islands. Methods We established 44 sampling sites along a directional gradient of precipitation, heat load, soil nitrogen, phosphorus and pH. Along this gradient, we estimated species abundances and measured three traits (plant height, leaf area and leaf thickness) on perennial endemic and non-endemic plant species. In total, we recorded traits for 1,223 plant individuals of 43 species. Subsequently, we calculated community-weighted mean traits to measure the relative contribution of species turnover, intraspecific variation and their covariation along the analysed gradient. Results The contribution of intraspecific variation to total variation was similar in endemic and non-endemic assemblages. For plant height, intraspecific variation explained roughly as much variation as species turnover. For leaf area and leaf thickness, intraspecific variation explained almost no variation. Species turnover effects mainly drove trait responses along the environmental gradient, but intraspecific variation was important for responses in leaf area to precipitation. Conclusions Despite their distinct evolutionary history, endemic and non-endemic plant assemblages show similar patterns in species turnover and intraspecific variation. Our results indicate that species turnover is the main component of trait variation in the underlying study system. However, intraspecific variation can increase individual species’ fitness in response to precipitation. Overall, our study challenges the theory that intraspecific trait variation is more important for the establishment of non-endemic species compared with endemic species.publishedVersio

Intraspecific trait variation and community assembly in old-field grasslands

Trait-based approaches are increasingly used in plant community ecology, but previous research has largely ignored functional trait variation within species. Here I investigated the role of intraspecific trait variation in community assembly and responses to spatial and temporal environmental variation in old-field plant communities in the eastern United States. In the first study I analyzed spatial patterns of functional divergence in old fields in central New York on spatial scales from 1-1500 m. Results showed that spatial divergence in functional traits at the community and intraspecific levels corresponded with spatial heterogeneity in edaphic variables, consistent with predicted patterns resulting from trait-based environmental filtering. In the second study I tested for evidence of environmental filtering and niche differentiation based on trait dispersion patterns, with or without accounting for intraspecific trait variation. The tests provided evidence of strong trait-based environmental filtering and weak niche differentiation, and these patterns were strengthened by the inclusion of intraspecific trait variation, demonstrating its importance for community assembly. In the third study I examined the contributions of intraspecific variation and species turnover to community trait responses to environmental gradients across a 1200-km latitudinal extent in the eastern United States. Community trait shifts in response to broad-scale climatic variation were driven primarily by species turnover, but intraspecific variation contributed strongly to trait shifts along edaphic gradients and at fine spatial scales. Finally I investigated the role of intraspecific variation in community trait responses to experimental nutrient enrichment in old-field communities and the influence of community functional diversity and dispersal in mediating these responses. After three years, community functional responses were driven almost entirely by intraspecific trait shifts, which were strongest in communities with high initial intraspecific variation for some traits. Taken together, my results suggest that intraspecific trait variation plays a strong role in the assembly of old-field plant communities and shed light on the circumstances in which intraspecific variation is likely to be important for plant community ecology in general

Intraspecific phenotypic variability of plant functional traits in contrasting mountain grasslands habitats

Empirical studies that link plants intraspecific variation to environmental conditions are almost lacking, despite their relevance in understanding mechanisms of plant adaptation, in predicting the outcome of environmental change and in conservation. Here, we investigate intraspecific trait variation of four grassland species along with abiotic environmental variation at high spatial resolution (n = 30 samples per species trait and environmental factor per site) in two contrasting grassland habitats in Central Apennines (Italy). We test for phenotypic adaptation between habitats, intraspecific trait-environment relationships within habitats, and the extent of trait and environmental variation. We considered whole plant, clonal, leaf, and seed traits. Differences between habitats were tested using ANOVA and ANCOVA. Trait-environment relationships were assessed using multiple regression models and hierarchical variance partitioning. The extent of variation was calculated using the coefficient of variation. Significant intraspecific differences in trait attributes between the contrasting habitats indicate phenotypic adaptation to in situ environmental conditions. Within habitats, light, soil temperature, and the availability of nitrate, ammonium, magnesium and potassium were the most important factors driving intraspecific trait-environment relationships. Leaf traits and height growth show lower variability than environment being probably more regulated by plants than clonal traits which show much higher variability. We show the adaptive significance of key plant traits leading to intraspecific adaptation of strategies providing insights for conservation of extant grassland communities. We argue that protecting habitats with considerable medium- and small-scale environmental heterogeneity is important to maintain large intraspecific variability within local populations that finally can buffer against uncertainty of future climate and land use scenarios

Intraspecific variation in functional traits in the wolf spider Lycosa fasciiventris : Implications for trophic cascades

Intraspecific variation has recently been acknowledged as an important factor affecting ecosystems. Indeed, levels of intraspecific variation in natural populations can be very high, even surpassing interspecific variation. In particular, variation in foraging traits can significantly impact ecological processes. The aim of this thesis was to measure the relative strength of drivers of intraspecific variation in foraging traits in the cannibalistic wolf-spider Lycosa fasciiventris and its potential impacts on trophic interactions and consequently trophic cascades. We evaluated trait variation using a half-sib split brood design, by crossing each male with two females and separating offspring from each family into 2 different rearing environments. The offspring was scored for several morphological, physiological and behavioral traits and heritability, maternal effects and environmental interactions (genotype-by-environment and maternal-by-environment interactions) were determined as well as genetic and maternal correlations. Maternal effects were predominant over additive genetic effects in all traits and their correlations, except in traits related to cannibalism, in which both genetic and maternal effects were absent. In this case, trait variation was explained by the social environment faced by spiders (conspecific cues). We then evaluated the impacts of intraspecific variation in ecological processes by performing mesocosms experiments. To this aim, we experimentally manipulated intraspecific variation and evaluated its effects upon trophic cascades. Results showed that variation in foraging traits due to maternal and environmental effects can modulate ecological processes, namely trophic cascades. Mesocosms with higher trait diversity displayed stronger trophic cascades, attributable not to a higher prey mortality but to a change in their behavior, while environmental diversity was reflected in a higher rate of cannibalism but not enough to dampen trophic cascades. The results of this thesis highlight the importance of maternal effects and other indirect genetic effects as drivers of intraspecific variation, modulating ecological processes and shaping community structure

A Role for Gene Duplication and Natural Variation of Gene Expression in the Evolution of Metabolism

Background: Most eukaryotic genomes have undergone whole genome duplications during their evolutionary history. Recent studies have shown that the function of these duplicated genes can diverge from the ancestral gene via neo- or subfunctionalization within single genotypes. An additional possibility is that gene duplicates may also undergo partitioning of function among different genotypes of a species leading to genetic differentiation. Finally, the ability of gene duplicates to diverge may be limited by their biological function. Methodology/Principal Findings: To test these hypotheses, I estimated the impact of gene duplication and metabolic function upon intraspecific gene expression variation of segmental and tandem duplicated genes within Arabidopsis thaliana. In all instances, the younger tandem duplicated genes showed higher intraspecific gene expression variation than the average Arabidopsis gene. Surprisingly, the older segmental duplicates also showed evidence of elevated intraspecific gene expression variation albeit typically lower than for the tandem duplicates. The specific biological function of the gene as defined by metabolic pathway also modulated the level of intraspecific gene expression variation. The major energy metabolism and biosynthetic pathways showed decreased variation, suggesting that they are constrained in their ability to accumulate gene expression variation. In contrast, a major herbivory defense pathway showed significantly elevated intraspecific variation suggesting that it may be under pressure to maintain and/or generate diversity in response t