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opencc-zeroMay 2022View details →

Niche overlap in rodents increases with competition but not ecological opportunity: A role of inter-individual difference

<div> Niche variation at population level mediates niche packing (i.e., patterns of species' spread within the niche space) and species coexistence at community level. Competition and ecological opportunity (resource diversity) are two of the main mechanisms underlying niche variation. Dense niche packing could occur through increased niche partitioning or increased niche overlap. In this study we used stable carbon and nitrogen isotope data of 635 individual rodents from 4 species across 9 sites in the montane region of a subtropical island to test the effects of competition and ecological opportunity on population isotope niche size, inter-individual niche difference within population, and inter-specific niche overlap within community. We used the Bayesian Standard Ellipse Area (SEAB, the ellipse area enclosed by carbon and nitrogen isotope values of organisms on a bi-plot) to estimate population niche size and inter-specific niche overlap. Inter-individual niche difference within population was quantified as isotopic divergence and isotopic uniqueness. We used rodent abundance (the number of unique individuals captured) to measure competition and plant isotope niche size (plant SEAB) to measure ecological opportunity. The rodents experienced competition as evidenced by a negative relationship between population change rate and conspecific abundance. Rodent population niche size increased with ecological opportunity but not competition. The inter-individual niche difference (isotopic uniqueness) increased with competition (inter-specific competition only) but not ecological opportunity. At community level, inter-specific niche overlap (herbivore—omnivore pair only) increased with competition (the combined abundance of the pair) but not ecological opportunity. This study demonstrated that isotope niche variation of the rodents could be hierarchically influenced by ecological opportunity and competition, with the former setting the limit of population niche size across communities and the latter shaping inter-individual niche difference and inter-specific niche overlap within communities. Under strong intra-specific competition and limited ecological opportunity for niche expansion, individuals may choose to increase their isotopic uniqueness from conspecifics at the cost of overlapping with heterospecifics of different trophic roles within the community niche space as overall competition increases. Denser niche packing of these rodent communities might be achieved through increased niche overlap. </div>

opencc-zeroNov 2022View details →

The opportunity for selection: an important but slippery concept in ecology and evolution.

1. The concept of the opportunity for selection (I), measured as the variance in relative fitness, is over 60 years old, yet remains poorly understood by, or even unknown to, many ecologists and evolutionary biologists. This essay aims to clarify key conceptual and practical issues concerning use and estimation of I, which represents a theoretical upper limit on the rate of evolutionary adaptation. 2. The component of I caused by linear selection on a single trait is equal to the square of its standardised selection differential i. Even if no phenotypic selection occurs (i=0), however, realised I will typically be nonzero, owing to environmental or stochastic variation in fitness. 3. The opportunity for viability selection depends only on the mean survival rate, but selective mortality will typically account for only a small fraction of total mortality. 4. Fecundity selection is accompanied by expected overdispersion in reproductive success (variance > mean), but overdispersion can also occur for reasons unrelated to phenotype, or by chance. The estimated opportunity for fecundity selection can also vary independently of i if estimated mean reproductive success is affected by study design, e.g. offspring are counted at different life stages or a variable fraction are missed. 5. For these reasons, I alone should not be used to make inferences about selection in progress and its drivers. Nevertheless, some empirical studies have documented weak to moderate correlations between I and phenotypic selection, so variation in I or related metrics across ecological contexts might provide clues that unmeasured traits are under variable selection. 20-Oct-2022 --

publicNov 2022View details →

The opportunity for selection: an important but slippery concept in ecology and evolution.

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publicJun 2022View details →

Niche overlap in rodents increases with competition but not ecological opportunity: A role of inter-individual difference

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opencc-zeroDec 2015View details →

Data from: Ecological and social factors constrain spatial and temporal opportunities for mating in a migratory songbird

Many studies of sexual selection assume that individuals have equal mating opportunities and that differences in mating success result from variation in sexual traits. However, the inability of sexual traits to explain variation in male mating success suggests that other factors moderate the strength of sexual selection. Extrapair paternity is common in vertebrates and can contribute to variation in mating success and thus serves as a model for understanding the operation of sexual selection. We developed a spatially explicit, multifactor model of all possible female-male pairings to test the hypothesis that ecological (food availability) and social (breeding density, breeding distance, and the social mate's nest stage) factors influence an individual's opportunity for extrapair paternity in a socially monogamous bird, the black-throated blue warbler, Setophaga caerulescens. A male's probability of siring extrapair young decreased with increasing distance to females, breeding density, and food availability. Males on food-poor territories were more likely to sire extrapair young, and these offspring were produced farther from the male's territory relative to males on food-abundant territories. Moreover, males sired extrapair young mostly during their social mates' incubation stage, especially males on food-abundant territories. This study demonstrates how ecological and social conditions constrain the spatial and temporal opportunities for extrapair paternity that affect variation in mating success and the strength of sexual selection in socially monogamous species.

opencc-zeroOct 2019View details →

Data from: Ecological opportunity shapes a large Arctic charr species radiation

Ecological opportunity is considered a crucial factor for adaptive radiation. Here, we combine genetic, morphological and ecological data to assess species and ecomorphological diversity of Artic charr in six lakes of a catchment in southernmost Greenland, harbouring only charr and stickleback. Because the diversity of habitats and resources increases with lake size, we predict a positive association between lake size and the extent of ecomorphological diversity. The largest lake of the catchment harbours the largest Arctic charr assemblage known today. It consists of six genetically differentiated species belonging to five ecomorphs (anadromous, littoral benthic, profundal dwarf, planktivorous, piscivorous), of which the latter comprises two ecomorphologically extremely similar species. Lakes of intermediate size contain two ecomorphologically and genetically distinct species. Small lakes harbour one genetically homogenous, yet sometimes ecomorphologically variable population. Supporting our prediction, lake size is positively correlated with the extent of ecomorphological specialization towards profundal, pelagic and piscivorous lifestyle. Furthermore, assemblage-wide morphospace increases sharply when more than one genetic cluster is present. Our data suggest that ecological opportunity and speciation jointly determine phenotypic expansion in this charr radiation.

opencc-zeroApr 2022View details →

Code and data from: Competition among small individuals hinders adaptive radiation despite ecological opportunity

Ontogenetic diet shifts, where individuals change their resource use during development, are the rule rather than the exception in the animal world. Here, we aim to understand how such changes in diet during development affect the conditions for an adaptive radiation in the presence of ecological opportunity. We use a size-structured consumer–resource model and the adaptive dynamics approach to study the ecological conditions for speciation. We assume that small individuals all feed on a shared resource. Large individuals, on the other hand, have access to multiple food sources on which they can specialize. We find that competition among small individuals can hinder an adaptive radiation to unfold, despite plenty of ecological opportunity for large individuals. When small individuals experience strong competition for food, they grow slowly and only a few individuals are recruited to the larger size classes. Hence, competition for food among large individuals is weak and there is therefore no disruptive selection. In addition, initial conditions determine if an adaptive radiation occurs or not. A consumer population initially dominated by small individuals will not radiate. On the other hand, a population initially dominated by large individuals may undergo adaptive radiation and diversify into multiple species.

zenodo36/100

Data for: Ecological impacts of extreme climatic events on terrestrial and freshwater biota in the Arctic: A synthesis of current scientific evidence and opportunities

File contains the results of a literature review on the ecological impacts of extreme climatic events on terrestrial and freshwater biota in the Arctic.

opencc-by-4.0Sep 2021View details →

zenodo36/100

Dataset for Tanguay & Herzog et al. (2023), Opportunities for, and barriers to anticipatory governance of two lake social-ecological systems in Germany and Canada, in People and Nature

This is the dataset for an article published in People and Nature by Tanguay & Herzog et al. (2023), entitled Opportunities for, and barriers to anticipatory governance of two lake social-ecological systems in Germany and Canada. It includes the data used for the literature review as well as the interview and workshop data for both case studies. As the research was overviewed by the <a href="https://ciereh.uqam.ca/">Comité institutionnel d’éthique de la recherche avec des êtres humains (CIEREH)</a>, some of the non-anonymized data were not archived.

opencc-by-4.0Feb 2023View details →

publicApr 2022View details →

Code and data from: Competition among small individuals hinders adaptive radiation despite ecological opportunity

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publicOct 2016View details →

Data from: Ecological and social factors constrain spatial and temporal opportunities for mating in a migratory songbird

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publicSep 2025View details →

Ecological opportunity spurred adaptive radiation of Central Mexican Silversides: Evidence from functional and morphometric traits

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publicOct 2019View details →

Data from: Ecological opportunity shapes a large Arctic charr species radiation

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opencc-zeroDec 2015View details →

Data from: The cryptic origins of evolutionary novelty: 1,000-fold-faster trophic diversification rates without increased ecological opportunity or hybrid swarm

Ecological opportunity is frequently proposed as the sole ingredient for adaptive radiation into novel niches. An additional trigger may be genome-wide hybridization resulting from 'hybrid swarm'. However, these hypotheses have been difficult to test due to the rarity of comparable control environments lacking adaptive radiations. Here I exploit such a pattern in microendemic radiations of Caribbean pupfishes. I show that a sympatric three-species radiation on San Salvador Island, Bahamas diversified 1,445 times faster than neighboring islands in jaw length due to evolution of a novel scale-eating adaptive zone from a generalist ancestral niche. I then sampled 22 generalist populations on seven neighboring islands and measured morphological diversity, stomach content diversity, dietary isotopic diversity, genetic diversity, lake/island areas, macroalgae richness, and Caribbean-wide patterns of gene flow. None of these standard metrics of ecological opportunity or gene flow were associated with adaptive radiation, except for slight increases in macroalgae richness. Thus, exceptional trophic diversification is highly localized despite myriad generalist populations in comparable environmental and genetic backgrounds. This study provides a strong counterexample to the ecological/hybrid-swarm theories of adaptive radiation and suggests that diversification of novel specialists on a sparse fitness landscape is constrained by more than ecological opportunity and gene flow.

opencc-zeroDec 2011View details →

Data from: Ecological opportunity and diversification in a continental radiation of birds: climbing adaptations and cladogenesis in the Furnariidae

Ecological theories of adaptive radiation predict that ecological opportunity stimulates cladogenesis through its effects on competitive release and niche expansion. Given that key innovations may confer ecological opportunity, we investigate the effect of the acquisition of climbing adaptations on rates of cladogenesis in a major avian radiation, the Neotropical bird family Furnariidae, using a species-level phylogeny. Morphological specializations for vertical climbing originated in the woodcreepers ca. 23 Mya, well before that adaptation occurred in woodpeckers (Picidae) or in other potential competitors in South America. This suggests that the acquisition of climbing adaptations conferred ample ecological opportunity to early woodcreepers. Nonetheless, we found that increases in speciation rates in Furnariidae did not coincide with the acquisition of climbing adaptations, and that the relationship between the accumulation of climbing adaptations and rates of speciation was negative. In addition, we did not detect a diversity-dependent decline in woodcreeper diversification rates consistent with saturation of the trunk-climbing niche. These findings do not support the hypothesis that ecological opportunity related to trunk-foraging stimulated cladogenesis in this radiation. The negative effect of climbing on diversification may be mediated by an indirect positive effect of climbing on dispersal ability, which may reduce speciation rates over evolutionary time scales.

opencc-zeroDec 2013View details →

Data from: Ecological opportunities and specializations shaped genetic divergence in a highly mobile marine top predator

Environmental conditions can shape genetic and morphological divergence. Release of new habitats during historical environmental changes was a major driver of evolutionary diversification. Here, forces shaping population structure and ecotype differentiation ('pelagic' and 'coastal') of bottlenose dolphins in the North-east Atlantic were investigated using complementary evolutionary and ecological approaches. Inference of population demographic history using approximate Bayesian computation indicated that coastal populations were likely founded by the Atlantic pelagic population after the Last Glacial Maxima probably as a result of newly available coastal ecological niches. Pelagic dolphins from the Atlantic and the Mediterranean Sea likely diverged during a period of high productivity in the Mediterranean Sea. Genetic differentiation between coastal and pelagic ecotypes may be maintained by niche specializations, as indicated by stable isotope and stomach content analyses, and social behaviour. The two ecotypes were only weakly morphologically segregated in contrast to other parts of the World Ocean. This may be linked to weak contrasts between coastal and pelagic habitats and/or a relatively recent divergence. We suggest that ecological opportunity to specialize is a major driver of genetic and morphological divergence. Combining genetic, ecological and morphological approaches is essential to understanding the population structure of mobile and cryptic species.

opencc-zeroDec 2010View details →

Data from: Adaptive radiation and ecological opportunity in Sulawesi and Philippine fanged frog (Limnonectes) communities.

Because island communities are derived from the mainland, they are often less diverse by comparison. However, reduced complexity of island communities can also present ecological opportunities. For example, amphibian diversity on the Indonesian island of Sulawesi is generally lower than in the Philippines, but this island supports a surprisingly diverse endemic assemblage of Sulawesi fanged frogs (genus Limnonectes). To explore evolutionary dynamics of this system, we examined molecular, morphological, and geographical variation of fanged frogs from these two regions. Using genealogical concordance – a conservative standard – we identified 12 species on Sulawesi, only four of which are described. One more species can be distinguished with morphology, and a Bayesian approach to species delimitation suggests our total species estimate on Sulawesi (n = 13) is still an underestimate. After accounting for evolutionary history, a model with multiple body size optima in sympatric Limnonectes species is significantly preferred over a "random walk" model where body size evolves by Brownian motion. Additionally, morphological variation is higher among sympatric than non-sympatric species on Sulawesi, but not in the Philippines. Taken together, these findings suggest that adaptive radiation of fanged frogs on Sulawesi was driven by natural selection to infiltrate ecological niches occupied by other lineages in the Philippines. Our study supports the concept of ecological opportunity in community assembly: diversification in mature communities, such as the Philippines, is limited by a dearth of unoccupied ecological niches. On Sulawesi however, evolutionary novelties originated in a predictable and replicated fashion in response to opportunities presented by a depauperate ancestral community.