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 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 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

The Stabilizing Effect Of Intraspecific Genetic Variation On Population Dynamics In Novel And Ancestral Habitats

Recent studies show that intraspecific genetic variation in asexual species may have large effects on community and ecosystem functions, increasing their stability, productivity, and species richness. However, major questions regarding its population-level impact remain empirically unanswered: (a) How does intraspecific genetic diversity affect the ecological characteristics of sexual species, in which recombination can alter the outcome of causal mechanisms such as selection and niche diversification? (b) Does genetic diversity increase population dynamic stability? (c) Is the impact of genetic diversity dependent on the selective environment? To answer these questions, I founded replicate flour beetle (Tribolium castaneum) populations with different degrees of ecologically relevant, heritable trait variation and monitored their dynamics for approximately eight generations. I show that population stability and persistence increased with greater genetic variation but that the stabilizing effect was independent of the selective habitat (different proportions of ancestral and novel resources). Alleles from a single founding strain underwent a selective sweep in the homogeneous ancestral habitat but not in a novel heterogeneous habitat. These results expand current understanding of the ecological impacts of genetic diversity by showing that genetically more diverse sexual populations persist longer and are more stable but that the selective environment determines the mechanistic basis of increased stability.Integrative Biolog

Balcus violaceus (Fabricius) : senior synonym of Balcus niger Sharp and B. signatus Broun (Coleoptera: Cleridae: Clerinae)

The elytra of Balcus signatus Broun (Coleoptera: Cleridae: Clerinae) from New Zealand have pale markings. Such markings, most prominently found in females, represent intraspecific variations of Balcus violaceus (Fabricius). Accordingly, Balcus signatus Brown is synonymized with Notoxus violaceus Fabricius, new synonymy. Four habitus figures of Balcus violaceus (Fabricius) are presented to display the range of elytral color variation in the species

A new species of Peckia (Diptera: Sarcophagidae) from Costa Rica : with a note on P. pexata (Wulp)

A new species of Peckia Robineau-Desvoidy is described from the coastal dry forest of Guanacaste Province, Costa Rica, viz., Pechia glyphis sp.n., and a key to the ten species of Peckia known from the area is provided. A lectotype is designated for Pechia pexata (Wulp, 1895) and intraspecific variation in male leg setosity and in the morphology of male terminalia are documented

The Effects of Intraspecific Variation of Crayfish Behavior on Nutrient Cycling in Aquatic Environments

Human activities are rapidly altering species traits at a global scale. Yet, there remains a critical need to determine whether trait variation within species affects ecosystem responses to global change. In particular, intraspecific variation in feeding behavior can have strong effects on ecosystem processes, such as nutrient cycling in streams. Crayfish are dominant consumers in streams and play key roles in controlling important stream dynamics such as nutrient cycling. We hypothesized that within-population, individual variation in crayfish foraging behavior is associated with differences in nutrient excretion. The objectives of this study were to (i) to quantify individual differences in foraging behavior and boldness of crayfish using a giving up density (GUD) approach. (ii) to quantify individual differences in nutrient excretion of crayfish. (iii) to test whether foraging rate, boldness, and excretion rate are repeatable traits in the laboratory setting and (iv) to examine whether there is a relationship between individual variation in foraging rate, boldness, and excretion. These objectives were explored with both behavioral and excretion assays, and general linear and nonlinear mixed models as well as ANOVA tests. We found that behavior and excretion were repeatable and that behavior is associated with ammonium excretion. The finding that crayfish foraging behavior is associated with differences in nutrient excretion has important implications for invasion ecology and nutrient cycling. It is known that behavioral changes occur along with invasion. These behavioral changes can significantly impact the nutrient excretion, and therefore nutrient dynamics within invaded environments.No embargoAcademic Major: Environmental Scienc