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In spatially extended ecosystems, habitat heterogeneity facilitates coexistence of species if each competitor experiences environmental conditions in a particular habitat that provide a growth advantage compared to other species, thereby making it locally competitively superior. If the competitive hierarchy among species is the same everywhere, heterogeneity‐facilitated coexistence is possible provided that superior competitors disperse maladaptively towards unfavourable habitats or if they hedge insufficiently against fluctuating environmental conditions. We use a generic two‐patch metacommunity model to show that the latter mechanisms also operate in metacommunities with homogeneous habitat quality when heterogeneous biomass distributions emerge from self‐organised pattern formation. The model consists of an abiotic resource, an autotroph producer and two competing heterotroph consumer species of which one is always competitively inferior to the other, irrespective of resource availability. If the induced biomass patterns are static in time, a lower dispersal rate can allow the inferior competitor to avoid competitive exclusion by retaining most of its biomass in the patch with the higher resource density. However, if the biomass patterns fluctuate spatio‐temporally, the inferior competitor must adopt a higher dispersal rate than the superior competitor to persist. This increased movement enables the inferior competitor to effectively distribute its biomass across space, thereby achieving a higher growth rate during periods of recovery from local population minima. Strikingly, we find a novel coexistence mechanism that emerges if the competitors differ in their abilities to induce pattern formation. Similar to relative nonlinearity in resource use (based e.g. on a gleaner–opportunist trade‐off), the dominant species modifies the spatial or spatio‐temporal variation in the distribution of the resource in a way that favours its competitor. This prevents competitive exclusion due to differently effective dispersal strategies. We conclude that while temporal instabilities that cause, for example, predator–prey oscillations are usually regarded as jeopardising species' persistence, spatial instabilities that give rise to self‐organised pattern formation should be interpreted more positively, as they provide a generic mechanisms for maintaining diversity in metacommunities without requiring a priori habitat heterogeneity. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Asexual organisms are ubiquitous. While being members of a single species with the same ecological requirements, multiple asexual genotypes within a species are often found in a single habitat. Niche partitioning in time and space among genotypes has been proposed to explain this phenomenon. However, it is not clear whether these different genotypes co‐occur in the long term.Therefore, we examined the population dynamics of two asexual Daphnia cf. pulex genotypes (JPN1 and JPN2) over 9 years in a small mountain lake. These two genotypes consistently occurred in the same seasons and layers, suggesting that niche partitioning cannot explain their long‐term co‐occurrence. The abundance of JPN1 was typically higher in most years. However, the abundance of dormant eggs in lake sediments was at the same level between the genotypes.Results of a laboratory experiment showed that JPN1 competitively excluded JPN2. However, many JPN2 individuals produced dormant eggs before JPN1 competitively excluded them from the experiment. Furthermore, the competitively inferior JPN2 produced dormant eggs abundantly in the medium containing a crowding cue from JPN1 while no such trend was observed for JPN1.These results showed that a competitively inferior asexual genotype could maintain a population with a competitively superior genotype for a long period of time because it had the ability to detect an increase in competitors and produce dormant eggs each year before being competitively eliminated.Based on these results, we suggest that the variation in genotype‐specific response in dormant egg production to environmental change plays a key role in the long‐term co‐occurrence of different asexual genotypes in single habitats. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Despite considerable theoretical interest in how the evolution of phenotypic plasticity should be shaped by environmental variability and stochasticity, how individuals actually respond to these aspects of the environment within their own lifetimes remains unclear.We propose that this understanding has been hampered by experimental approaches that expose organisms to fluctuating environments (typically treatments where fluctuations in the environment are cyclical vs. erratic) for a pre‐determined duration while ensuring that the mean environment over that the entire exposure period is invariable. This approach implicitly assumes that responses to the mean and variance/predictability in the environment occur over the same time‐scale. If this assumption is false, one potential outcome is that phenotypic differences among the treatment groups might arise in response to differences in the mean environment that are present over shorter time periods among those same treatment groups.We illustrate an experimental design that (a) creates variation in the level of environmental predictability, (b) allows for estimation of the time‐scale over which the phenotypic response to the mean environment occurs and (c) permits statistical estimation of the effect of predictability in the environmental variable of interest while controlling for any effect of the mean environment over the relevant temporal scale.Using the clonally reproducing zooplankton species Daphnia magna, we test for within‐generation plasticity in the ability to tolerate high temperature following exposure to multiple temperature treatments with the same overall mean, but where the pattern of fluctuations differed among them. This approach revealed that heat tolerance in Daphnia was not influenced by variability in temperature per se nor the predictability of fluctuations in temperature but adjusted in response to the mean temperature they experienced 24 hr prior to measurement.Our results suggest that conclusions arising from studies that employ a single manipulation of environmental predictability and which cannot consider such potentially confounding effects may be premature. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Understanding the complete dispersal process is important for making realistic predictions of species distributions, but mechanisms for diaspore release in wind-dispersed species are often unknown. However, diaspore release under conditions that increase the probability of longer dispersal distances and mechanisms that extend dispersal events in time may have evolutionary advantages., We quantified air humidity thresholds regulating spore release in the moss Brachythecium rutabulum. We also investigated the prevailing micrometeorological conditions when these thresholds occur in nature and how they affect dispersal distances up to 100 m, using a mechanistic dispersal model., We show that moss spores were mainly released when the peristome teeth were opening, as relative air humidity ( RH) decreased from high values to relatively low (mainly between 90% and 75% RH). This most often occurred in the morning, when wind speeds were relatively low. Surprisingly, the model predicted that an equally high proportion of the spores would travel distances beyond 100 m (horizontally) when released in the wind conditions prevailing during events of RH decrease in the morning, that lead to peristome opening, as in the highest wind speeds. Moreover, a higher proportion of the spores reached high altitudes when released at the lower wind speeds during the morning compared to the higher speeds later in the day, indicating a possibility for extended dispersal distances when released in the morning. Dispersal in the morning is enhanced by a combination of a more unstable atmospheric surface layer that promotes vertical dispersal, and a lower wind speed that decreases the spore deposition probability onto the ground, compared to later in the day., Our study demonstrates an active spore release mechanism in response to diurnally changing air humidity. The mechanism may promote longer dispersal distances, because of enhanced vertical dispersal and because spores being released in the morning have more time to travel before the wind calms down at night. The mechanism also leads to a prolonged dispersal period over the season, which may be viewed as a risk spreading in time that ultimately also leads to a higher diversity of establishment conditions, dispersal distances and directions. [ABSTRACT FROM AUTHOR]

1. Variation in the quality of the offspring environment can lead to the evolution of variable offspring provisioning. For variable offspring provisioning to evolve, the magnitude of provisioning per offspring must have effects on offspring and parental fitness. 2. Females of the quacking frog, Crinia georgiana, produce clutches of eggs in which egg size varies between individuals in the population and also within clutches, independent of female size or condition. A trade-off between egg size and number exists. 3. Using microsatellite markers to trace offspring to parents, and therefore clutch type, we tested the performance of tadpoles from clutches of large, small and variable-sized eggs in ponds in the field. 4. Clutches of large eggs resulted in the highest parental fitness and clutches of small eggs resulted in lower parental fitness values. 5. The parental fitness indicated that conditions in these ponds were harsh. Clutches with variable egg sizes had intermediate parental fitness but may be of benefit as a bet-hedging strategy when the qualities of ponds are unpredictable. 6. This study provides new empirical evidence of important offspring and parental fitness consequences of variable maternal provisioning under natural conditions in the field and demonstrates the importance of moving experimental life-history studies out of the laboratory into the field where realistic selection pressures act on developing offspring. [ABSTRACT FROM AUTHOR]

1. Although metabolic resource losses are maintained at low rates during diapause, the accumulation of losses over a long period negatively affects organisms with prolonged diapause usually extending beyond 1 year. The seed-predatory weevil Exechesops leucopis (Jordan) (Coleoptera: Anthribidae) enters winter diapause at the final-instar larval stage within seeds of Styrax japonica Sieb. et Zucc. (Styracaceae) at a density of one larva per seed. After diapause, larvae pupate within the seeds and then emerge as adults. 2. The adult emergence pattern of a single cohort of E. leucopis was monitored for 5 years under seminatural conditions in the laboratory. The duration of diapause varied from 1 year (single winter) to 4 years (four winters). Adults that emerged after 1 year were smaller than those that emerged after 2 years or more. When temperature was not decreased experimentally in winter, no adults emerged in the following season. 3. Metabolic resource losses during diapause were examined by comparing adult body sizes between controls and groups in which emergence was delayed by 1 year under manipulated winter temperature regimes. Adults that emerged after an additional year in the larval stage were smaller than those in the control group. Moreover, the rates of reduction in body size as a consequence of diapause being extended experimentally were greater in smaller individuals. Thus smaller individuals have disadvantages in longer diapause, suggesting that weevils may vary the duration of diapause depending on individual body size. 4. Exechesops leucopis shows sexual dimorphism in the degree of eye protrusion. Eyestalk length affects male fitness through intrasexual selection. The duration of diapause affected the length of the eyestalks: when an additional year was spent in diapause, eyestalk length was nearly maintained in larger males but was greatly decreased in smaller males. In all females eyestalk length decreased according to the duration of diapause. [ABSTRACT FROM AUTHOR]

1. Multiple breeding (raising more than one batch of young per breeding season) is a common life-history tactic, but little is known as yet of the accompanying costs and benefits. Second clutches of Great Tits, a facultative multiple breeder, were removed over three years to investigate the costs of rearing a second clutch. 2. Female parents, but not males, survived significantly better than unmanipulated control birds when the second clutch was removed. The difference between the sexes indicates a potential sexual conflict over the decision to start a second clutch. In neither sex were effects found on egg production in the next year. However, birds of both sexes produced more fledglings from first clutches in the following year when the second clutch had been removed. 3. In males, the experimental effect on fledgling production in the next year could be attributed to their mates, because this effect was restricted to males that bred with the same female as in the previous year. In females, this effect was also found among birds that bred with a new mate, which suggests that rearing a second clutch had a long-term effect. Females, but not males, found roosting in the following winter had lower mass when the second clutch had been removed, which supports the conclusion that rearing a second clutch has long-term effects. 4. The experimental effect on female survival was found in two winters with low food availability, but not in a winter with high food availability. This is in agreement with the results of a non-experimental analysis of data collected in the same population. The effect on fledgling production in the next year was also restricted to years with low food availability in the intervening winter. This suggests that the costs of rearing a second clutch depend on food availability in winter. The possibility that the costs of reproduction generally depend on environmental quality and possible mechanisms are discussed. 5. Food availability in winter is... [ABSTRACT FROM AUTHOR]