Browsing by Subject "life-history evolution"

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  • Aykanat, Tutku; Ozerov, Mikhail; Vähä, Juha-Pekka; Orell, Panu; Niemelä, Eero; Erkinaro, Jaakko; Primmer, Craig R. (2019)
    Co-inheritance in life-history traits may result in unpredictable evolutionary trajectories if not accounted for in life-history models. Iteroparity (the reproductive strategy of reproducing more than once) in Atlantic salmon (Salmo salar) is a fitness trait with substantial variation within and among populations. In the Teno River in northern Europe, iteroparous individuals constitute an important component of many populations and have experienced a sharp increase in abundance in the last 20 years, partly overlapping with a general decrease in age structure. The physiological basis of iteroparity bears similarities to that of age at first maturity, another life-history trait with substantial fitness effects in salmon. Sea age at maturity in Atlantic salmon is controlled by a major locus around the vgll3 gene, and we used this opportunity demonstrate that these two traits are co-inherited around this genome region. The odds ratio of survival until second reproduction was up to 2.4 (1.8-3.5 90% CI) times higher for fish with the early-maturing vgll3 genotype (EE) compared to fish with the late-maturing genotype (LL). The L allele was dominant in individuals remaining only one year at sea before maturation, but the dominance was reversed, with the E allele being dominant in individuals maturing after two or more years at sea. Post hoc analysis indicated that iteroparous fish with the EE genotype had accelerated growth prior to first reproduction compared to first-time spawners, across all age groups, whereas this effect was not detected in fish with the LL genotype. These results broaden the functional link around the vgll3 genome region and help us understand constraints in the evolution of life-history variation in salmon. Our results further highlight the need to account for genetic correlations between fitness traits when predicting demographic changes in changing environments.
  • Prokkola, Jenni M.; Åsheim, Eirik R.; Morozov, Sergey; Bangura, Paul; Erkinaro, Jaakko; Ruokolainen, Annukka; Primmer, Craig R.; Aykanat, Tutku (2022)
    A better understanding of the genetic and phenotypic architecture underlying life-history variation is a longstanding aim in biology. Theories suggest energy metabolism determines life-history variation by modulating resource acquisition and allocation trade-offs, but the genetic underpinnings of the relationship and its dependence on ecological conditions have rarely been demonstrated. The strong genetic determination of age-at-maturity by two unlinked genomic regions (vgll3 and six6) makes Atlantic salmon (Salmo salar) an ideal model to address these questions. Using more than 250 juveniles in common garden conditions, we quantified the covariation between metabolic phenotypes-standard and maximum metabolic rates (SMR and MMR), and aerobic scope (AS)-and the life-history genomic regions, and tested if food availability modulates the relationships. We found that the early maturation genotype in vgll3 was associated with higher MMR and consequently AS. Additionally, MMR exhibited physiological epistasis; it was decreased when late maturation genotypes co-occurred in both genomic regions. Contrary to our expectation, the life-history genotypes had no effects on SMR. Furthermore, food availability had no effect on the genetic covariation, suggesting a lack of genotype-by-environment interactions. Our results provide insights on the key organismal processes that link energy use at the juvenile stage to age-at-maturity, indicating potential mechanisms by which metabolism and life-history can coevolve.
  • Aykanat, Tutku; Rasmussen, Martin; Ozerov, Mikhail; Niemelä, Eero; Paulin, Lars; Vähä, Juha-Pekka; Hindar, Kjetil; Wennevik, Vidar; Pedersen, Torstein; Svenning, Martin-A.; Primmer, Craig R. (2020)
    1. Animals employ various foraging strategies along their ontogeny to acquire energy, and with varying degree of efficiencies, to support growth, maturation and subsequent reproduction events. Individuals that can efficiently acquire energy early are more likely to mature at an earlier age, as a result of faster energy gain which can fuel maturation and reproduction. 2. We aimed to test the hypothesis that heritable resource acquisition variation that covaries with efficiency along the ontogeny would influence maturation timing of individuals. 3. To test this hypothesis, we utilized Atlantic salmon as a model which exhibits a simple, hence trackable, genetic control of maturation age. We then monitored the variation in diet acquisition (quantified as stomach fullness and composition) of individuals with different ages, and linked it with genomic regions (haploblocks) that were previously identified to be associated with age-at-maturity. 4. Consistent with the hypothesis, we demonstrated that one of the life-history genomic regions tested (six6) was indeed associated with age-dependent differences in stomach fullness. Prey composition was marginally linked tosix6, and suggestively (but non-significantly) tovgll3genomic regions. We further showed Atlantic salmon switched to the so-called 'feast and famine' strategy along the ontogeny, where older age groups exhibited heavier stomach content, but that came at the expense of running on empty more often. 5. These results suggest genetic variation underlying resource utilization may explain the genetic basis of age structure in Atlantic salmon. Given that ontogenetic diet has a genetic component and the strong spatial diversity associated with these genomic regions, we predict populations with diverse maturation age will have diverse evolutionary responses to future changes in marine food web structures.
  • Aykanat, Tutku; Rasmussen, Martin; Ozerov, Mikhail; Niemelä, Eero; Paulin, Lars; Vähä, Juha-Pekka; Hindar, Kjetil; Wennevik, Vidar; Pedersen, Torstein; Svenning, Martin-A.; Primmer, Craig R. (2020)
    1. Animals employ various foraging strategies along their ontogeny to acquire energy, and with varying degree of efficiencies, to support growth, maturation and subsequent reproduction events. Individuals that can efficiently acquire energy early are more likely to mature at an earlier age, as a result of faster energy gain which can fuel maturation and reproduction. 2. We aimed to test the hypothesis that heritable resource acquisition variation that covaries with efficiency along the ontogeny would influence maturation timing of individuals. 3. To test this hypothesis, we utilized Atlantic salmon as a model which exhibits a simple, hence trackable, genetic control of maturation age. We then monitored the variation in diet acquisition (quantified as stomach fullness and composition) of individuals with different ages, and linked it with genomic regions (haploblocks) that were previously identified to be associated with age-at-maturity. 4. Consistent with the hypothesis, we demonstrated that one of the life-history genomic regions tested (six6) was indeed associated with age-dependent differences in stomach fullness. Prey composition was marginally linked tosix6, and suggestively (but non-significantly) tovgll3genomic regions. We further showed Atlantic salmon switched to the so-called 'feast and famine' strategy along the ontogeny, where older age groups exhibited heavier stomach content, but that came at the expense of running on empty more often. 5. These results suggest genetic variation underlying resource utilization may explain the genetic basis of age structure in Atlantic salmon. Given that ontogenetic diet has a genetic component and the strong spatial diversity associated with these genomic regions, we predict populations with diverse maturation age will have diverse evolutionary responses to future changes in marine food web structures.
  • Vaumourin, Elise; Laine, Anna-Liisa (2018)
    Understanding processes maintaining variation in pathogen life-history traits is a key challenge in disease biology, and of importance for predicting when and where risks of disease emergence are highest. Pathogens are expected to encounter tremendous levels of variation in their environment - both abiotic and biotic - and this variation may promote maintenance of variation in pathogen populations through space and time. Here, we measure life-history traits of an obligate fungal pathogen at both asexual and sexual stages under both single infection and coinfection along a temperature gradient. We find that temperature had a significant effect on all measured life-history traits while coinfection only had a significant effect on the number of sexual resting structures produced. The effect of temperature on life-history traits was both direct as well as mediated through a genotype-by-temperature interaction. We conclude that pathogen life-history traits vary in their sensitivity to abiotic and biotic variation in the environment.
  • Norros, Veera Maria; Karhu, Elina; Nordén, Jenni; Vähätalo, Anssi Vesa; Ovaskainen, Otso Tapio (2015)
    Assessment of the costs and benefits of dispersal is central to understanding species' life-history strategies as well as explaining and predicting spatial population dynamics in the changing world. While mortality during active movement has received much attention, few have studied the costs of passive movement such as the airborne transport of fungal spores. Here, we examine the potential of extreme environmental conditions to cause dispersal mortality in wood-decay fungi. These fungi play a key role as decomposers and habitat creators in forest ecosystems and the populations of many species have declined due to habitat loss and fragmentation. We measured the effect of simulated solar radiation (including ultraviolet A and B) and freezing at -25 degrees C on the spore germinability of 17 species. Both treatments but especially sunlight markedly reduced spore germinability in most species, and species with thin-walled spores were particularly light sensitive. Extrapolating the species' laboratory responses to natural irradiance conditions, we predict that sunlight is a relevant source of dispersal mortality at least at larger spatial scales. In addition, we found a positive effect of spore size on spore germinability, suggesting a trade-off between dispersal distance and establishment. We conclude that freezing and particularly sunlight can be important sources of dispersal mortality in wood-decay fungi which can make it difficult for some species to colonize isolated habitat patches and habitat edges.
  • Uusi-Heikkilä, Silva; Whiteley, Andrew R.; Kuparinen, Anna; Matsumura, Shuichi; Venturelli, Paul A.; Wolter, Christian; Slate, Jon; Primmer, Craig R.; Meinelt, Thomas; Killen, Shaun S.; Bierbach, David; Polverino, Giovanni; Ludwig, Arne; Arlinghaus, Robert (2015)
    Size-selective harvesting is assumed to alter life histories of exploited fish populations, thereby negatively affecting population productivity, recovery, and yield. However, demonstrating that fisheries-induced phenotypic changes in the wild are at least partly genetically determined has proved notoriously difficult. Moreover, the population-level consequences of fisheries-induced evolution are still being controversially discussed. Using an experimental approach, we found that five generations of size-selective harvesting altered the life histories and behavior, but not the metabolic rate, of wild-origin zebrafish (Danio rerio). Fish adapted to high positively size selective fishing pressure invested more in reproduction, reached a smaller adult body size, and were less explorative and bold. Phenotypic changes seemed subtle but were accompanied by genetic changes in functional loci. Thus, our results provided unambiguous evidence for rapid, harvest-induced phenotypic and evolutionary change when harvesting is intensive and size selective. According to a life-history model, the observed life-history changes elevated population growth rate in harvested conditions, but slowed population recovery under a simulated moratorium. Hence, the evolutionary legacy of size-selective harvesting includes populations that are productive under exploited conditions, but selectively disadvantaged to cope with natural selection pressures that often favor large body size.