Life-history strategies in freshwater macroinvertebrates

• 1 Explaining spatial and temporal differences in species assemblages is a central aim of ecology. It requires a sound understanding of the causal mechanisms underlying the relationship of species with their environment. A species trait is widely acknowledged to be the key that links pattern and process, although the enormous variety of traits hampers generalization about which combination of traits are adaptive in a particular environment.
• 2 In three steps, we used species traits to match species and environment, and chose lentic freshwater ecosystems to illustrate our approach. We first identified key environmental factors and selected the species traits that enable the organism to deal with them. Secondly, we investigated how investments in these traits are related (e.g. through trade‐offs). Thirdly, we outlined 13 life‐history strategies, based on biological species traits, their interrelations known from life‐history theory and their functional implications.
• 3 Species traits and environmental conditions are connected through life‐history strategies, with different strategies representing different solutions to particular ecological problems. In addition, strategies may present an integrated response to the environment as they are based on many different traits and their interrelationships. The presence and abundance of (species exhibiting) different life‐history strategies in a location may therefore give direct information about how a particular environment is experienced by the species present.
• 4 Life‐history strategies can be used to (i) explain differences in species assemblages either between locations or in different periods; (ii) compare waterbodies separated by large geographical distances, which may comprise different regional species pools or span species distribution areas and (iii) reduce often very complex, biodiverse assemblages into a few meaningful, easily interpretable relationships.

     

Metacommunity structure of aquatic gastropods in a river floodplain: the role of niche breadth and drift propensity

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Relating life‐history traits,environmental constraints and local extinctions in river fish

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Manipulating waterbody hydroperiod affects movement behaviour and occupancy dynamics in an amphibian

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Phylogenetic effects on functional traits and life history strategies of Australian freshwater fish

Understanding the biogeographic and phylogenetic basis to interspecific differences in species’ functional traits is a central goal of evolutionary biology and community ecology. We quantify the extent of phylogenetic influence on functional traits and life‐history strategies of Australian freshwater fish to highlight intercontinental differences as a result of Australia's unique biogeographic and evolutionary history. We assembled data on life history, morphological and ecological traits from published sources for 194 Australian freshwater species. Interspecific variation among species could be described by a specialist–generalist gradient of variation in life‐history strategies associated with spawning frequency, fecundity and spawning migration. In general, Australian fish showed an affinity for life‐history strategies that maximise fitness in hydrologically unpredictable environments. We also observed differences in trait lability between and within life history, morphological and ecological traits where in general morphological and ecological traits were more labile. Our results showed that life‐history strategies are relatively evolutionarily labile and species have potentially evolved or colonised in freshwaters frequently and independently allowing them to maximise population performance in a range of environments. In addition, reproductive guild membership showed strong phylogenetic constraint indicating that evolutionary history is an important component influencing the range and distribution of reproductive strategies in extant species assemblages. For Australian freshwater fish, biogeographic and phylogenetic history contribute to broad taxonomic differences in species functional traits, while finer scale ecological processes contribute to interspecific differences in smaller taxonomic units. These results suggest that the lability or phylogenetic relatedness of different functional traits affects their suitability for testing hypothesis surrounding community level responses to environmental change.     

Life history influences the vulnerability of New Zealand galaxiids to invasive salmonids

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Environmental,spatial and phylogenetic determinants of fish life‐history traits and functional composition of Australian rivers

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Do metacommunity theories explain spatial variation in fish assemblage structure in a pristine tropical river?

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Dark diversity in Amazonian stream fish communities: What factors determine species absence along environmental gradients?

1. Species distribution models often fail to predict observed patterns of species diversity, and this is because some species within a regional pool that are tolerant of conditions at a given location may nevertheless be absent from the local community. These missing species have been termed “dark diversity”. In the present study, we investigated which factors explain dark diversity among fish assemblages in Amazonian streams.
2. We sampled 71 streams in areas with different types of land use within two river basins and estimated dark diversity from patterns of species co-occurrence, using Beals’ index, along environmental gradients. From this procedure, taxa are designated as dark diversity components when they are absent from a given stream, but often co-occur with the local species at other streams, indicating similar ecological requirements. We used generalised linear models both to determine whether environmental or landscape variables, connectivity, instream environmental heterogeneity or some combination of these factors explained dark diversity of fishes, and to evaluate whether ecomorphology is associated with the extent to which a species contributes to dark diversity and which specific traits contribute the most to explaining variation in dark diversity.
3. Mean local diversity exceeded observed dark diversity. The magnitude of dark diversity was directly associated with the proportion of secondary forest in the immediate catchment and with the index of proximity to anthropogenic impact. Species that have high affinity for environments with higher current velocity, low swimming ability and that capture food mainly on the surface contributed more to dark diversity, which suggests that swimming ability, habitat preference and aspects related to diet are key predictors of the probability that a given species will be present at locations with suitable habitat.
4. Our findings reinforce the idea that dark diversity results from interactions between species traits and environmental factors, including anthropogenic impacts. Understanding the interplay among environmental factors and species traits that contribute to dark diversity provides targets for improved ecosystem restoration and sustainability of native species assemblages.

     

The effect of multi‐species host density on superparasitism and sex ratio in a gregarious parasitoid

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Food availability as a major driver in the evolution of life‐history strategies of sibling species

Life‐history theory predicts trade‐offs between reproductive and survival traits such that different strategies or environmental constraints may yield comparable lifetime reproductive success among conspecifics. Food availability is one of the most important environmental factors shaping developmental processes. It notably affects key life‐history components such as reproduction and survival prospect. We investigated whether food resource availability could also operate as an ultimate driver of life‐history strategy variation between species. During 13 years, we marked and recaptured young and adult sibling mouse‐eared bats (Myotis myotis and Myotis blythii) at sympatric colonial sites. We tested whether distinct, species‐specific trophic niches and food availability patterns may drive interspecific differences in key life‐history components such as age at first reproduction and survival. We took advantage of a quasi‐experimental setting in which prey availability for the two species varies between years (pulse vs. nonpulse resource years), modeling mark‐recapture data for demographic comparisons. Prey availability dictated both adult survival and age at first reproduction. The bat species facing a more abundant and predictable food supply early in the season started its reproductive life earlier and showed a lower adult survival probability than the species subjected to more limited and less predictable food supply, while lifetime reproductive success was comparable in both species. The observed life‐history trade‐off indicates that temporal patterns in food availability can drive evolutionary divergence in life‐history strategies among sympatric sibling species.     

Linking seed germination and plant height: a case study of a wetland community on the eastern Tibet Plateau

• Seed germination is the earliest trait expressed in a plant's life history, and it can directly affect the expression of post‐germination traits. Plant height is central to plant ecological strategies, because it is a major determinant of the ability of a species to compete for light. Thus, linking seed germination and plant height at the community level is very important to understanding plant fitness and community structure.
• Here, we tested storage condition and temperature requirements for germination of 31 species from a wetland plant community on the eastern Tibet Plateau and analysed correlation of germination traits with plant height in relation to storage condition.
• Germination percentage was positively related to plant height, and this relationship disappeared when seeds were incubated at a low temperature (i.e. 5 °C) or after they were stored under wet‐cold conditions. The response of seeds to dry+wet–cold storage was negatively related to plant height. Based on the scores of each species on the first two principal components derived from PCA, species were classified into two categories by hierarchical clustering, and there was a significant difference between germination and plant height of species in these two categories.
• These results suggest that the requirements for seed germination together with seasonal change in environmental conditions determine the window for germination and, in turn, plant growth season and resource utilisation and ultimately plant height.

     

Classification of Reynolds phytoplankton functional groups using individual traits and machine learning techniques

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Trait flexibility of generalist invertebrates exposed to contrasting predation and drying stressors

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Dammed rivers: impoundments facilitate fish invasions

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Landscape‐scale life‐history gradients in New Zealand freshwater fish

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A continental‐scale analysis of fish assemblage functional structure in European rivers

The theory of traits (life‐history, ecological and biological traits) states that a species’ characteristics might enable its persistence and development in given environmental conditions. If environment is the major factor controlling functional assemblage structure, species with similar attributes are expected to inhabit a similar environment. This study uses trait states in 849 European riverine fish assemblages to analyze the influence of environment, phylogeny and biogeography on the functional structure of these assemblages. European fish assemblages were highly structured and two main syndromes (a suite of coevolved traits) were observed: 1) assemblages dominated by stenothermal intolerant individuals and 2) assemblages dominated by eurythermal, eurytopic and tolerant individuals. Temperature and stream physical structure were the two main environmental factors explaining the diversity of fish assemblage functional structures, while the influence of biogeographic factors was weak, once environment was taken into account. This suggests that, whatever the regional species pool, similar assemblage functional structures will be found in similar environmental conditions. The phylogenetic relatedness between species might also explain to some extent the associations between the species traits observed among European fish assemblages.     

Environmental variation is a major predictor of global trait turnover in mammals

Aim

To evaluate how environment and evolutionary history interact to influence global patterns of mammal trait diversity (a combination of 14 morphological and life‐history traits).

Location

The global terrestrial environment.

Taxon

Terrestrial mammals.

Methods

We calculated patterns of spatial turnover for mammalian traits and phylogenetic lineages using the mean nearest taxon distance. We then used a variance partitioning approach to establish the relative contribution of trait conservatism, ecological adaptation and clade specific ecological preferences on global trait turnover.

Results

We provide a global scale analysis of trait turnover across mammalian terrestrial assemblages, which demonstrates that phylogenetic turnover by itself does not predict trait turnover better than random expectations. Conversely, trait turnover is consistently more strongly associated with environmental variation than predicted by our null models. The influence of clade‐specific ecological preferences, reflected by the shared component of phylogenetic turnover and environmental variation, was considerably higher than expectations. Although global patterns of trait turnover are dependent on the trait under consideration, there is a consistent association between trait turnover and environmental predictive variables, regardless of the trait considered.

Main conclusions

Our results suggest that changes in phylogenetic composition are not always coupled with changes in trait composition on a global scale and that environmental conditions are strongly associated with patterns of trait composition across species assemblages, both within and across phylogenetic clades.     

Are patterns in the taxonomic,biological and ecological traits of water beetles congruent in Mediterranean ecosystems?

1. Coleoptera species show considerable diversity in life histories and ecological strategies, which makes possible their wide distribution in freshwater habitats, including highly stressed ones such as saline or temporary waterbodies. Explaining how particular combinations of traits allow species to occupy distinctive habitats is a central question in ecology. 2. A total of 212 sites, sampled over a wide range of inland aquatic habitats in the south‐eastern Iberian Peninsula, yielded 272 species belonging to 68 genera and 11 families. The affinities of genera for 11 biological and 11 ecological traits, gathered from literature and the authors’ own expertise, were used to assess the degree of congruence between taxonomic, biological and ecological traits. 3. Taxonomic richness was significantly related to the number of both biological and ecological trait categories, with the richest families also showing the highest functional and ecological diversity. A fuzzy correspondence analysis performed on the abundance‐weighed array of biological traits separated genera according to categories of diet, feeding habits, respiration, reproduction and locomotion. A similar analysis of ecological traits revealed that preferences related to longitudinal distribution (headwater to mouth), local habitat and current velocity best discriminated genera. At the family level, there was a distinctive functional grouping of genera based on biological traits. Only Elmidae showed noticeable homogeneity across genera for both biological and ecological traits. 4. Co‐inertia analysis demonstrated a significant match between biological and ecological traits (Rv‐correlation = 0.35, P < 0.001). Elmidae genera displayed the highest concordance, whereas Hydraenidae demonstrated the lowest. 5. These results indicate that the predominance of habitat filtering processes in headwater streams yields biological trait conservatism (as shown by Elmidae genera), as well as trait convergence for some specific traits (for instance, respiration) among certain Dytiscidae genera and other typical rheophilic taxa, whereas other biotic factors, such as competition among species, appear more prominent in less stressed habitats. Further knowledge of traits, especially regarding physiological capabilities, is needed to better understand water beetle life history strategies.