Höfundur: hilduryr@matis.is

Current patterns of meat consumption are considered unsustainable. Plant-based products are presented as a solution. However, while some plant-based products thrive, others do not make the cut due to the information “framing” effect issues related to the way information is presented to the consumers. Information on the nutrition and health properties of food products are usually made available at the point of purchase, but their effect on consumer product evaluation and subsequent purchase intent can also occur later, during or after consumption. This research demonstrates that the effect of nutrition information on product evaluation and purchase intention depends on when such information is made available–before first tasting or after first tasting–and that the information interacts with the taste experience in its effect on product evaluation and subsequent purchase intent. Using three plant-based products as an example, we conducted a cross-cultural experimental sensory evaluation with temporal order of information as the main between-subject experimental condition (informed before taste vs. informed after taste vs. control condition), and product experience phase (expectation vs. experience vs. post-experience phase) and information content as within-subject conditions. Information content had two levels: lower vs. higher share of oat protein in the product (i.e., source of protein vs. high in protein). The results indicate that information generally increases consumers’ purchase intentions with information before tasting having a higher weight when compared to the condition when information was presented after tasting. Presenting the information before tasting also mitigates a drop in the evaluation of taste after tasting, observed in the two other conditions. Further, taste acts as a healthiness cue, but the direction of the inference depends on the availability of health-related information: tasting in the informed condition increased the healthiness perception, whereas tasting in the uninformed condition had the opposite effect. Giving the information before the first tasting also increased the weight of healthiness as compared to taste in the formation of purchase intentions. These findings contribute to a better understanding of the effect of temporal order of information and product tasting have on the consumers’ product evaluations of plant-based products from theoretical and managerial perspectives.

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Tengiliður

Davíð Gíslason

Verkefnastjóri

davidg@matis.is

Resource polymorphism has been proposed as an important phase of diversification and speciation in vertebrates. Studies of fish in young lakes of the Northern Hemisphere indicate variably advanced cases of adaptive trophic diversification. We have previously proposed a scheme describing this variation in terms of a gradient of resource-based polymorphic traits, emphasizing flexible behaviour in early phases and morphological divergence in more advanced phases. Here, we present data on Arctic char (Salvelinus alpinus) in Icelandic lakes exhibiting a variable degree of phenotypic and genotypic segregation. We show that (i) the morphs are at different levels of phenotypic segregation and reproductive isolation and in one case completely reproductively isolated, (ii) morphs within lakes appear to be of intralacustrine origin, and (iii) the morphological and genetic divergence of morphs is correlated, suggesting a role for trophic adaptation as a driving force in morph segregation.

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Tengiliður

Davíð Gíslason

Verkefnastjóri

davidg@matis.is

The biology of Brown trout (Salmo trutta) and Arctic charr (Salvelinus alpinus) was studied in four Faroese lakes in late July – early August 2000. Relative density and condition of Brown trout were lowest in Leynavatn and highest in Saksunarvatn. Arctic charr only occurred in Leynavatn, where it outnumbered Brown trout by a factor of 2.7. For all fish populations, growth rates were slow, fish were small and maximum age of fish was low. The oldest fish in Toftavatn was 5+yr and the oldest fish in the study, in Saksunarvatn, was 9+yr. Asymptotic length was ca. 21 cm for arctic charr in Leynavatn and ca. 25 cm for Brown trout in both Leynavatn and Toftavatn, but for Brown trout in Eystara Mjáavatn andSaksunarvatn, no asymptote was observed. Small butsignificant differences in morphology were observedamong Brown trout populations with corresponding differences in diet. Brown trout in Toftavatn had a more forked caudal fin and the diet was more pelagic/epiben- thic than in the other lakes. In Leynavatn, Brown trout fed more on benthic diet and had a more curved snout than Brown trout in the other lakes, which may be signs of character displacement resulting from interspecific competition with Arctic charr. The Arctic charr in Leynavatn did not show signs of morphological or ecological polymorphism and their diet was both of benthic and planktonic origin. Genetic analyses of Arctic charr showed minor variation at most loci, high homozygosity and genotypic disequilibrium between three loci, indicating extensive inbreeding and random genetic drift in a small, isolated population. It is suggested that the restriction of Arctic charr to one natural lake in the Faroe Islands is primarily due to unfavourable water temperatures. Evidence suggests that the slow growth, small size and short lifespan of Arctic charr and Brown trout in Leynavatn may be due to interspecific competition between the two species along with relatively poor food conditions in the lake.

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Tengiliður

Davíð Gíslason

Verkefnastjóri

davidg@matis.is

To examine the population genetic structure of lake-resident Arctic charr, Salvelinus alpinus from northwest Europe on multiple spatial scales, 2367 individuals from 43 lakes located in three geographical regions (Iceland, the British Isles and Scandinavia) were genotyped at six microsatellite loci. On a large scale, data provided little evidence to support clustering of populations according to geographical region. Hierarchical analysis of molecular variance indicated that, although statistically significant, only 2.17% of the variance in allelic frequencies was partitioned at the among-region level. Within regions, high levels of genetic differentiation were typically found between lakes regardless of the geographical distance separating them. These results are consistent with the hypothesis of rapid postglacial recolonization of all of northwest Europe from a single charr lineage, with subsequent restriction of gene flow. On a smaller scale, there was evidence for close genetic relationships among lakes from within common drainage basins in Scotland. Thus, interlake genetic structure reflects localized patterns of recent (or contemporary) gene flow superimposed onto a larger scale structure that is largely a result of historical processes. There was also evidence for widespread genetic structuring at the within-lake level, with sympatric populations detected in 10 lakes, and multilocus heterozygote deficits found in 23 lakes. This evidence of the Wahlund effect was found in all lakes known to contain discrete phenotypic morphs, as well as many others, suggesting that morphs may often represent separate breeding populations, and also that the phenomenon of polymorphism in this species may be more widespread than is currently realized.

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Tengiliður

Davíð Gíslason

Verkefnastjóri

davidg@matis.is

Harvest can change phenotypic traits of populations through immediate demographic consequences, evolutionary responses to harvest selection, or developmental responses by individuals. This study investigated the plastic phenotypic effects of harvest on size and age at maturity in a commercially exploited freshwater fish. We tested an individual growth and life history plasticity model using lagged correlations incorporating how harvesting of ages 2 and older fish influenced the abundance of juvenile fish, resource availability, individual growth rates, and carry-over responses in age and size at maturity. Our test used cohort data for Lake Erie yellow perch (Perca flavescens). Age and size at maturity fluctuated widely and rapidly across 23 cohorts between 1991 and 2013, suggesting phenotypic plasticity contributed strongly to maturation dynamics. The changes in maturity could not be explained by responses to harvest, as expected under the plasticity model. In Lake Erie, age and size at maturity in yellow perch appear to be responding to other drivers, such as harvest-induced dynamics of other fish stocks or ecosystem changes that are independent of harvest.

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Tengiliður

Davíð Gíslason

Verkefnastjóri

davidg@matis.is

Overexploitation and collapse of major fisheries raises important concerns about effects of harvest on fish populations. We tested for ecological and evolutionary mechanisms by which harvest could affect exploited fish populations in Lake Erie over the last four decades, over most of which intensive fisheries management was implemented. We did not detect evidence of long-term negative effects of harvest on yellow perch (Perca flavescens), walleye (Sander vitreus), white perch (Morone americana), or white bass (Morone chrysops) populations, either through recruitment success or through alteration of maturation schedules. Current fisheries management in Lake Erie has been relatively successful with respect to minimizing negative harvest effects, such that the dynamics of exploited fish populations in Lake Erie were more strongly affected by environment than harvest. Our study adds to the evidence that effective fisheries management is capable of rebuilding depleted fisheries and (or) maintaining healthy fisheries. Nevertheless, fisheries management needs to move beyond the ecological dimension to incorporate economic, social, and institutional aspects for society to be better assured of the sustainability of fisheries in rapidly changing ecosystems.

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