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| 2. |
- Brönmark, Christer, et al.
(author)
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Costs of inducible defence along a resource gradient.
- 2012
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In: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 7:1
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Journal article (peer-reviewed)abstract
- In addition to having constitutive defence traits, many organisms also respond to predation by phenotypic plasticity. In order for plasticity to be adaptive, induced defences should incur a benefit to the organism in, for example, decreased risk of predation. However, the production of defence traits may include costs in fitness components such as growth, time to reproduction, or fecundity. To test the hypothesis that the expression of phenotypic plasticity incurs costs, we performed a common garden experiment with a freshwater snail, Radix balthica, a species known to change morphology in the presence of molluscivorous fish. We measured a number of predator-induced morphological and behavioural defence traits in snails that we reared in the presence or absence of chemical cues from fish. Further, we quantified the costs of plasticity in fitness characters related to fecundity and growth. Since plastic responses may be inhibited under limited resource conditions, we reared snails in different densities and thereby levels of competition. Snails exposed to predator cues grew rounder and thicker shells, traits confirmed to be adaptive in environments with fish. Defence traits were consistently expressed independent of density, suggesting strong selection from predatory molluscivorous fish. However, the expression of defence traits resulted in reduced growth rate and fecundity, particularly with limited resources. Our results suggest full defence in predator related traits regardless of resource availability, and costs of defence consequently paid in traits related to fitness.
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| 4. |
- Hollander, Johan, et al.
(author)
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Rates of gene flow in a freshwater snail and the evolution of phenotypic plasticity
- 2017
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In: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 121:4, s. 764-770
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Journal article (peer-reviewed)abstract
- The evolution of phenotypic plasticity requires a number of conditions. Selection of plasticity is favoured when the organism experience environmental change, costs are low and cues are reliable about the environmental heterogeneity. However, organisms living in stable environments, not showing constitutive traits but a large amount of plasticity, are predicted to demonstrate high rates of gene flow in order for selection to favour the evolution of phenotypic plasticity, which accordingly should provide weak genetic structures across populations. We used the pulmonate freshwater gastropod Radix balthica, a species with known and considerable shell shape variation due to predator-induced plasticity, and used amplified fragment length polymorphism markers to test if the rate of gene flow can explain the evolution of phenotypic plasticity. Since R. balthica inhabit water bodies with different but consistent predator regimes, we envisaged a large dispersal rate. However, we found a contradictory result with clear population structures, even among adjacent ponds in southern Sweden. We discuss this apparent paradox in contrast to the evolution of ecotype formation, colonization mechanisms that have the potential to reduce gene flow and, in the context of costs of plasticity, we consider new perspectives about relaxed and variable selection that may drive the evolution of phenotypic plasticity.
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| 5. |
- Aad, G., et al.
(author)
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Readiness of the ATLAS Tile Calorimeter for LHC collisions
- 2010
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In: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:4, s. 1193-1236
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Journal article (peer-reviewed)abstract
- The Tile hadronic calorimeter of the ATLAS detector has undergone extensive testing in the experimental hall since its installation in late 2005. The readout, control and calibration systems have been fully operational since 2007 and the detector has successfully collected data from the LHC single beams in 2008 and first collisions in 2009. This paper gives an overview of the Tile Calorimeter performance as measured using random triggers, calibration data, data from cosmic ray muons and single beam data. The detector operation status, noise characteristics and performance of the calibration systems are presented, as well as the validation of the timing and energy calibration carried out with minimum ionising cosmic ray muons data. The calibration systems' precision is well below the design value of 1%. The determination of the global energy scale was performed with an uncertainty of 4%.
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| 6. |
- Bourdeau, P. E., et al.
(author)
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What can aquatic gastropods tell us about phenotypic plasticity? A review and meta-analysis
- 2015
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In: Heredity. - : Springer Science and Business Media LLC. - 0018-067X .- 1365-2540. ; 115:4, s. 312-321
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Journal article (peer-reviewed)abstract
- There have been few attempts to synthesise the growing body of literature on phenotypic plasticity to reveal patterns and generalities about the extent and magnitude of plastic responses. Here, we conduct a review and meta-analysis of published literature on phenotypic plasticity in aquatic (marine and freshwater) gastropods, a common system for studying plasticity. We identified 96 studies, using pre-determined search terms, published between 1985 and November 2013. The literature was dominated by studies of predator-induced shell form, snail growth rates and life history parameters of a few model taxa, accounting for 67% of all studies reviewed. Meta-analyses indicated average plastic responses in shell thickness, shell shape, and growth and fecundity of freshwater species was at least three times larger than in marine species. Within marine gastropods, species with planktonic development had similar average plastic responses to species with benthic development. We discuss these findings in the context of the role of costs and limits of phenotypic plasticity and environmental heterogeneity as important constraints on the evolution of plasticity. We also consider potential publication biases and discuss areas for future research, indicating well-studied areas and important knowledge gaps.
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| 7. |
- Brönmark, Christer, et al.
(author)
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Predator induced morphological plasticity across local populations of a fresh water snail
- 2011
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:7
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Journal article (peer-reviewed)abstract
- The expression of anti-predator adaptations may vary on a spatial scale, favouring traits that are advantageous in a given predation regime. Besides, evolution of different developmental strategies depends to a large extent on the grain of the environment and may result in locally canalized adaptations or, alternatively, the evolution of phenotypic plasticity as different predation regimes may vary across habitats. We investigated the potential for predator-driven variability in shell morphology in a freshwater snail, Radix balthica, and whether found differences were a specialized ecotype adaptation or a result of phenotypic plasticity. Shell shape was quantified in snails from geographically separated pond populations with and without molluscivorous fish. Subsequently, in a common garden experiment we investigated reaction norms of snails from populations' with/without fish when exposed to chemical cues from tench (Tinca tinca), a molluscivorous fish. We found that snails from fish-free ponds had a narrow shell with a well developed spire, whereas snails that coexisted with fish had more rotund shells with a low spire, a shell morphology known to increase survival rate from shell-crushing predators. The common garden experiment mirrored the results from the field survey and showed that snails had similar reaction norms in response to chemical predator cues, i.e. the expression of shell shape was independent of population origin. Finally, we found significant differences for the trait means among populations, within each pond category (fish/fish free), suggesting a genetic component in the determination of shell morphology that has evolved independently across ponds.
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| 8. |
- Conde-Padin, P., et al.
(author)
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Revealing the mechanisms of sexual isolation in a case of sympatric and parallel ecological divergence
- 2008
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In: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 94:3, s. 513-526
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Journal article (peer-reviewed)abstract
- Two ecotypes of a marine intertidal snail (Littorina saxatilis), living at different microhabitats and shore levels, have evolved in sympatry and in parallel across the Galician rocky shore. These ecotypes differ in many traits (including size) due to differential adaptation. They meet, mate assortatively, and partially hybridize at the mid shore where the two microhabitats overlap. The partial sexual isolation observed is claimed to be a side-effect of the size differences between ecotypes combined with a size assortative mating found in most populations of this species. We investigated this hypothesis using three complementary experimental approaches. First, we investigated which of the different shell variables contributed most to the variation in individual sexual isolation in the field by using two new statistics developed for that purpose: (1) pair sexual isolation and (2) r(i), which is based on the Pearson correlation coefficient. We found that size is the most important trait explaining the sexual isolation and, in particular, the males appear to be the key sex contributing to sexual isolation. Second, we compared the size assortative mating between regions: exposed rocky shore populations from north-westwern Spain (showing incomplete reproductive isolation due to size assortative mating) and protected Spanish and Swedish populations (showing size assortative mating but not reproductive isolation between ecomorphs). Most of the variation in size assortative mating between localities was significantly explained by the within-population level of variation on size. Third, we performed a laboratory male choice experiment, which further suggested that the choice is made predominantly on the basis of size. These results confirm the mechanism proposed to explain the sexual isolation in the Galician hybrid zone and thus support this case as a putative example of parallel incipient speciation. (C) 2008 The Linnean Society of London.
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| 10. |
- Edgell, Timothy, et al.
(author)
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The Evolutionary Ecology of European Green Crab, Carcinus maenas, in North America
- 2011
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In: In the wrong place: alien marine Crustaceans - distribution, biology and impacts. - Dordrecht : Springer Netherlands. - 9789400705913 - 9789400705906 ; , s. 641-659
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Book chapter (peer-reviewed)abstract
- Biological invasions offer fertile grounds for studying evolutionary ecology because species’ contact histories are uncharacteristically well-defined. As a result, invasions can be used to gain glimpses of the earliest micro-evolutionary responses of natural populations to new species’ interactions by studying changes in behaviour, physiology or morphology in space and time. Here, the known history of range expansion by the European green crab Carcinus maenas in North America is used to illustrate factors affecting invasion success and the resilience of native American prey. We situate our discussion in the bourgeoning field of adaptive phenotypic plasticity. Phenotypic plasticity is the phenomenon where an individual’s genotype interacts with its environment to produce better-fit behaviour, physiology, morphology, or life-history. Plasticity is considered adaptive when the environmentally-induced phenotype increases an individual’s fitness. Below, theory about phenotypic plasticity is reviewed as to why it may benefit invasive species in general and specifically Carcinus maenas. The plasticity-invasion hypothesis (i.e., biological invaders benefit from high levels of phenotypic plasticity) is then tested directly by comparing known levels in C. maenas and other invaders to plasticity in a diversity of non-invasive, marine invertebrates. This study also analyses whether phenotypic plasticity has helped North American prey species defend against escalated bouts of predation caused by the C. maenas invasion, and elucidates the role plasticity plays in an apparent case of predatorprey coevolution between C. maenas and at least one species of native gastropod, Littorina obtusata. Finally, knowledge gaps in the case studies presented are discussed along with suggestions for future research aimed at gaining a better appreciation for how plasticity guides phenotypic evolution after a biological invasion.
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