| 1. |
- Brännström, Åke, 1975-, et al.
(författare)
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Rigorous conditions for food-web intervality in high-dimensional trophic niche spaces
- 2011
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Ingår i: Journal of Mathematical Biology. - : Springerlink. - 0303-6812 .- 1432-1416. ; 63:3, s. 575-592
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Tidskriftsartikel (refereegranskat)abstract
- Food webs represent trophic (feeding) interactions in ecosystems. Since the late 1970s, it has been recognized that food-webs have a surprisingly close relationship to interval graphs. One interpretation of food-web intervality is that trophic niche space is low-dimensional, meaning that the trophic character of a species can be expressed by a single or at most a few quantitative traits. In a companion paper we demonstrated, by simulating a minimal food-web model, that food webs are also expected to be interval when niche-space is high-dimensional. Here we characterize the fundamental mechanisms underlying this phenomenon by proving a set of rigorous conditions for food-web intervality in high-dimensional niche spaces. Our results apply to a large class of food-web models, including the special case previously studied numerically.
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| 2. |
- Brännström, Åke, 1975-, et al.
(författare)
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Consequences of fluctuating group size for the evolution of cooperation
- 2011
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Ingår i: Journal of Mathematical Biology. - : SpringerLink. - 0303-6812 .- 1432-1416. ; 63:2, s. 263-281
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Tidskriftsartikel (refereegranskat)abstract
- Studies of cooperation have traditionally focused on discrete games such as the well-known prisoner’s dilemma, in which players choose between two pure strategies: cooperation and defection. Increasingly, however, cooperation is being studied in continuous games that feature a continuum of strategies determining the level of cooperative investment. For the continuous snowdrift game, it has been shown that a gradually evolving monomorphic population may undergo evolutionary branching, resulting in the emergence of a defector strategy that coexists with a cooperator strategy. This phenomenon has been dubbed the ‘tragedy of the commune’. Here we study the effects of fluctuating group size on the tragedy of the commune and derive analytical conditions for evolutionary branching. Our results show that the effects of fluctuating group size on evolutionary dynamics critically depend on the structure of payoff functions. For games with additively separable benefits and costs, fluctuations in group size make evolutionary branching less likely, and sufficiently large fluctuations in group size can always turn an evolutionary branching point into a locally evolutionarily stable strategy. For games with multiplicatively separable benefits and costs, fluctuations in group size can either prevent or induce the tragedy of the commune. For games with general interactions between benefits and costs, we derive a general classification scheme based on second derivatives of the payoff function, to elucidate when fluctuations in group size help or hinder cooperation.
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| 3. |
- Jang, Yun-Ting, et al.
(författare)
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The interactive effects of environmental gradient and dispersal shape spatial phylogenetic patterns
- 2022
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Ingår i: Frontiers in Ecology and Evolution. - : Frontiers Media S.A.. - 2296-701X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The emergence and maintenance of biodiversity include interacting environmental conditions, organismal adaptation to such conditions, and dispersal. To understand and quantify such ecological, evolutionary, and spatial processes, observation and interpretation of phylogenetic relatedness across space (e.g., phylogenetic beta diversity) is arguably a way forward as such patterns contain signals from all the processes listed above. However, it remains challenging to extract information about complex eco-evolutionary and spatial processes from phylogenetic patterns.Methods: We link environmental gradients and organismal dispersal with phylogenetic beta diversity using a trait-based and eco-evolutionary model of diversification along environmental gradients. The combined effect of the environment and dispersal leads to distinct phylogenetic patterns between subsets of species and across geographical distances.Results and discussion: Steep environmental gradients combined with low dispersal lead to asymmetric phylogenies, a high phylogenetic beta diversity, and the phylogenetic diversity between communities increases linearly along the environmental gradient. High dispersal combined with a less steep environmental gradient leads to symmetric phylogenies, low phylogenetic beta diversity, and the phylogenetic diversity between communities along the gradient increases in a sigmoidal form. By disentangling the eco-evolutionary mechanisms that link such interacting environment and dispersal effects and community phylogenetic patterns, our results improve understanding of biodiversity in general and help interpretation of observed phylogenetic beta diversity.
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| 4. |
- Nonaka, Etsuko, 1971-, et al.
(författare)
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Assortative mating can limit the evolution of phenotypic plasticity
- 2014
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Ingår i: Evolutionary Ecology. - : Springer. - 0269-7653 .- 1573-8477. ; 28:6, s. 1057-1074
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Tidskriftsartikel (refereegranskat)abstract
- Phenotypic plasticity, the ability to adjust phenotype to the exposed environment, isoften advantageous for organisms in heterogeneous environments. Although the degrees ofplasticity appear limited in nature, many studies have reported low costs of plasticity invarious species. Existing studies argue for ecological, genetic, or physiological costs orselection eliminating plasticity with high costs, but have not considered costs arising fromsexual selection. Here, we show that sexual selection caused by mate choice can impede theevolution of phenotypic plasticity in a trait used for mate choice. Plasticity can remain low tomoderate even in the absence of physiological or genetic costs, when individualsphenotypically adapted to contrasting environments through plasticity can mate with eachother and choose mates based on phenotypic similarity. Because the non-choosy sex (i.e.,males) with lower degrees of plasticity are more favored in matings by the choosy sex (i.e.,females) adapted to different environments, directional selection toward higher degrees ofplasticity is constrained by sexual selection. This occurs at intermediate strengths of femalechoosiness we tested. Our results demonstrate that mate choice is a potential source of anindirect cost to phenotypic plasticity.
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| 5. |
- Rossberg, Axel, et al.
(författare)
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How trophic interaction strength depends on traits : A conceptual framework for representing multidimensional trophic niche spaces
- 2010
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Ingår i: Theoretical Ecology. - : Springer Netrherlands. - 1874-1738 .- 1874-1746. ; 3:1, s. 13-24
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Tidskriftsartikel (refereegranskat)abstract
- A key problem in community ecology is to understand how individual-level traits give rise to population-level trophic interactions. Here, we propose a synthetic framework based on ecological considerations to address this question systematically. We derive a general functional form for the dependence of trophic interaction coefficients on trophically relevant quantitative traits of consumers and resources. The derived expression encompasses—and thus allows a unified comparison of—several functional forms previously proposed in the literature. Furthermore, we show how a community’s, potentially low-dimens ional, effective trophic niche space is related to its higher-dimensional phenotypic trait space. In this manner, we give ecological meaning to the notion of the “dimensionality of trophic niche space.” Our framework implies a method for directly measuring this dimensionality. We suggest a procedure for estimating the relevant parameters from empirical data and for verifying that such data matches the assumptions underlying our derivation.
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| 6. |
- Sumpter, David, 1973-, et al.
(författare)
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Synergy in social communication
- 2008
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Ingår i: Sociobiology of communication. - Oxford : Oxford University Press.
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Synergy is where the interactions of a group of individuals becomes more than the sum of their parts. In this chapter we review how, through the use of social communication, foraging animals can increase their rate of finding food. We discuss how mechanisms such as pheromone trails, dancing, and other signals act to increase group, and thus individual, success. We also discuss how social dilemmas can arise where costly signalling can be exploited by non-signallers. We show that under a range of conditions, specifically when group success increases more than linearly with group size, cooperative signalling can evolve without kin selection or reciprocity. This study serves to emphasise the importance in linking mechanism with function when studying collective behaviour of animals.
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| 7. |
- van Leeuwen, E., et al.
(författare)
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A generalized functional response for predators that switch between multiple prey species
- 2013
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Ingår i: Journal of Theoretical Biology. - London, England : Elsevier. - 0022-5193 .- 1095-8541. ; 328, s. 89-98
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Tidskriftsartikel (refereegranskat)abstract
- We develop a theory for the food intake of a predator that can switch between multiple prey species. The theory addresses empirical observations of prey switching and is based on the behavioural assumption that a predator tends to continue feeding on prey that are similar to the prey it has consumed last, in terms of, e.g., their morphology, defences, location, habitat choice, or behaviour. From a predator's dietary history and the assumed similarity relationship among prey species, we derive a general closed-form multi-species functional response for describing predators switching between multiple prey species. Our theory includes the Holling type II functional response as a special case and makes consistent predictions when populations of equivalent prey are aggregated or split. An analysis of the derived functional response enables us to highlight the following five main findings. (1) Prey switching leads to an approximate power-law relationship between ratios of prey abundance and prey intake, consistent with experimental data. (2) In agreement with empirical observations, the theory predicts an upper limit of 2 for the exponent of such power laws. (3) Our theory predicts deviations from power-law switching at very low and very high prey-abundance ratios. (4) The theory can predict the diet composition of a predator feeding on multiple prey species from diet observations for predators feeding only on pairs of prey species. (5) Predators foraging on more prey species will show less pronounced prey switching than predators foraging on fewer prey species, thus providing a natural explanation for the known difficulties of observing prey switching in the field. (C) 2013 Elsevier Ltd. All rights reserved.
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