Voltinism-associated differences in winter survival across latitudes: integrating growth, physiology, and food intake.

Species that span large latitudinal gradients face strong differences in voltinism and in winter conditions within their range. Latitudinal gradients in winter survival and especially their underlying mechanisms and association with voltinism patterns are poorly studied. We tested in the damselfly Enallagma cyathigerum whether high-latitude populations were better in dealing with the longer winters compared to central- and low-latitude populations and whether this was associated with changes in voltinism.

The interplay of adult and larval time constraints shapes species differences in larval life history.

In animals with a complex life cycle, larval life-history plasticity is likely shaped by the interplay of selective factors in both larval and adult stages. A wide interspecific variation in responses to larval time constraints imposed by seasonality has been documented. Few studies have addressed differences among closely related species in the evolutionary trajectories of age and size at metamorphosis and their link with larval growth rate under time constraints.

Local genetic adaptation generates latitude-specific effects of warming on predator-prey interactions.

Temperature effects on predator-prey interactions are fundamental to better understand the effects of global warming. Previous studies never considered local adaptation of both predators and prey at different latitudes, and ignored the novel population combinations of the same predator-prey species system that may arise because of northward dispersal. We set up a common garden warming experiment to study predator-prey interactions between Ischnura elegans damselfly predators and Daphnia magna zooplankton prey from three source latitudes spanning >1500 km.

Latitudinally structured variation in the temperature dependence of damselfly growth rates.

The Metabolic Theory of Ecology predicts that the slope of the rate-temperature relationship, E, remains consistent across traits and organisms, acting as a major determinant of large-scale ecological patterns. Although E has recently been shown to vary systematically, we have a poor understanding of its ecological significance. To address this question, we conducted a common-garden experiment involving six damselfly species differing in distribution, estimating E at the level of full-sib families.

Generalists and specialists along a latitudinal transect: patterns of thermal adaptation in six species of damselflies.

Tropical organisms colonizing temperate environments face reduced average temperatures and dramatic thermal fluctuations. Theoretical models postulate that thermal specialization should be favored either when little environmental variation is experienced within generations or when among-generation variation is small relative to within-generation variation. To test these predictions, we studied six temperate species of damselflies differing in latitudinal distribution.

Behaviour and physiology shape the growth accelerations associated with predation risk, high temperatures and southern latitudes in Ischnura damselfly larvae.

1. To better predict effects of climate change and predation risk on prey animals and ecosystems, we need studies documenting not only latitudinal patterns in growth rate but also growth plasticity to temperature and predation risk and the underlying proximate mechanisms: behaviour (food intake) and digestive physiology (growth efficiency). The mechanistic underpinnings of predator-induced growth increases remain especially poorly understood.

Latitudinal and voltinism compensation shape thermal reaction norms for growth rate.

Latitudinal variation in thermal reaction norms of key fitness traits may inform about the response of populations to climate warming, yet their adaptive nature and evolutionary potential are poorly known. We assessed the contribution of quantitative genetic, neutral genetic and environmental effects to thermal reaction norms of growth rate for populations of the damselfly Ischnura elegans. Among populations, reaction norms differed primarily in elevation, suggesting that time constraints associated with shorter growth seasons in univoltine, high-latitude as well as multivoltine, low-latitude populations selected for faster growth rates.

Rapid growth reduces cold resistance: evidence from latitudinal variation in growth rate, cold resistance and stress proteins.

Background: Physiological costs of rapid growth may contribute to the observation that organisms typically grow at submaximal rates. Although, it has been hypothesized that faster growing individuals would do worse in dealing with suboptimal temperatures, this type of cost has never been explored empirically. Furthermore, the mechanistic basis of the physiological costs of rapid growth is largely unexplored.

Predator-driven trait diversification in a dragonfly genus: covariation in behavioral and morphological antipredator defense.

Proof for predation as an agent shaping evolutionary trait diversification is accumulating, however, our understanding how multiple antipredator traits covary due to phenotypic differentiation is still scarce. Species of the dragonfly genus Leucorrhinia underwent shifts from lakes with fish as top predators to fishless lakes with large dragonfly predators. This move to fishless lakes was accompanied by a partial loss and reduction of larval spines.

Autotomy reduces immune function and antioxidant defence.

Costs of autotomy, an antipredator defence, are typically explained by impaired mobility; yet physiologically mediated costs may also play a role. Given the resemblance to wounding, a decreased immune function and an associated reduction in antioxidant defence is expected after autotomy. In line with this, after lamellae autotomy, larvae of the damselfly Lestes viridis showed lower levels of innate immunity (i.

Compensatory growth and oxidative stress in a damselfly.

Physiological costs of compensatory growth are poorly understood, yet may be the key components in explaining why growth rates are typically submaximal. Here we tested the hypothesized direct costs of compensatory growth in terms of oxidative stress. We assessed oxidative stress in a study where we generated compensatory growth in body mass by exposing larvae of the damselfly Lestes viridis to a transient starvation period followed by ad libitum food.

Correcting the short-term effect of food deprivation in a damselfly: mechanisms and costs.

1. Mass at emergence is a life-history trait strongly linked to adult fitness. Therefore, when faced with transient food shortage in the larval stage, mass-correcting mechanisms are common.

Life-history evolution when Lestes damselflies invaded vernal ponds.

We know little about the macroevolution of life-history traits along environmental gradients, especially with regard to the directionality compared to the ancestral states and the associated costs to other functions. Here we examine how age and size at maturity evolved when Lestes damselflies shifted from their ancestral temporary pond habitat (i.e.

Physiological costs of compensatory growth in a damselfly.

Little is known about physiological costs of rapid growth. We successfully generated compensatory growth to time stress and transient food stress in the damselfly Lestes viridis and studied the physiological correlates of the resulting reduced ability to cope with starvation. We found evidence for both mechanisms proposed to underlie the physiological trade-off: compensatory growth was associated with (1) a higher metabolic rate, as indicated by a higher oxygen consumption and a faster depletion of energy storage molecules (glycogen and triglycerides), and (2) a smaller investment in energy storage.

Time constraints mediate predator-induced plasticity in immune function, condition, and life history.

The simultaneous presence of predators and a limited time for development imposes a conflict: accelerating growth under time constraints comes at the cost of higher predation risk mediated by increased foraging. The few studies that have addressed this tradeoff have dealt only with life history traits such as age and size at maturity. Physiological traits have largely been ignored in studies assessing the impact of environmental stressors, and it is largely unknown whether they respond independently of life history traits.

Spatiotemporal allozyme variation in the damselfly, Lestes viridis (Odonata: Zygoptera): gene flow among permanent and temporary ponds.

Several insect species seem to persist not only in permanent but also in temporary ponds where they face particularly harsh conditions and frequent extinctions. Under such conditions, gene flow may prevent local adaptation to temporary ponds and may promote phenotypic plasticity, or maintain apparent population persistence. The few empirical studies on insects suggest the latter mechanism, but no studies so far quantified gene flow including both pond types.

Life-history variation in relation to time constraints in a damselfly.

Although variation within populations in plasticity to time constraints is expected with regard to hatching date, empirical studies are largely lacking. We studied life-history responses to time constraints manipulated by photoperiod and associated with hatching date in larvae of the damselfly Lestes viridis for two populations with a different hydroperiod. In a common garden experiment, early- and late-hatched larvae from both populations were reared at two photoperiods mimicking the start and the end of the egg-hatching season.

Lethal and sublethal costs of autotomy and predator presence in damselfly larvae.

We studied the costs of lamellae autotomy with respect to growth and survival of Lestes sponsa damselfly larvae in field experiments. We manipulated predation risk by Aeshna cyanea dragonfly larvae and lamellae status of L. sponsa larvae in field enclosures and compared differences in numbers, size and mass of survivors among treatments.