Biology subjects

Lind, M. I.

Publications and source records attributed to Lind, M. I..

13 recordsLinked to original sources

bioRxiv2026

Small-scale within-drainage spawning behavior causes population differentiation in Atlantic salmon

Understanding the genetic structure of keystone species within river networks is essential for effective conservation and management. While population differentiation of anadromous species often occurs between river systems, less research has been conducted on differentiation within rivers with smaller catchment areas. In this study, we investigated the population genetic structure of wild Atlantic salmon (Salmo salar) across the small-scale river Ronne [a] system in southernmost Sweden using Restriction-site Associated DNA sequencing (RADseq). Although the Admixture analysis did not detect clearly defined genetic clusters, significant pairwise FST values and DAPC revealed emerging population differentiation among the Ronne [a] tributaries. The observed patterns are consistent with a system characterized by connectivity, where genetic flow is present but can be reduced by behavioral and ecological factors such as spawning homing behavior and selective movements. These findings suggest that, despite overall connectivity, Atlantic salmon populations in the Ronne [a] catchment area may function as partially independent sub-populations. This highlights the importance of conservation and management strategies in fragmented river systems to consider population genetic structure to support resilient salmon populations under ongoing anthropogenic pressures.

molecular biology↗

bioRxiv2026

Transgenerational inheritance is variable across Caenorhabditis worms

Transgenerational epigenetic inheritance (TEI) allows organisms to express heritable responses to environmental stresses, and can potentially contribute to adaptive evolution. The microbivorous model organism Caenorhabditis elegans is perhaps the best example, as it can learn to avoid pathogenic Pseudomonas bacteria and transmit this learned avoidance to its offspring. However, the extent to which TEI is widespread in nature remains unclear, and therefore our understanding of the generality of this response is limited. To address this, we conducted the first comparative study of TEI across five Caenorhabditis nematode worm species (C. kamaaina, C. elegans, C. tropicalis, C. remanei and C. briggsae). These species differ in RNA interference competence and in the degree of sequence homology between Caenorhabditis worm genes and bacterial RNAs, two factors thought to influence epigenetic responses. We examined transgenerational avoidance of P. vranovensis, a pathogen that reduces fitness in all five species tested. In addition to C. elegans, we found that C. remanei also exhibited transgenerational avoidance of P. vranovensis, whereas neither learning nor inheritance was observed in the other three species. In addition, parental exposure to P. vranovensis also conferred a transgenerational survival benefit upon pathogen encounter in C. elegans, C. remanei and C. tropicalis. Our findings show that TEI of pathogen avoidance extends beyond C. elegans but is not a general response across Caenorhabditis species. This shows that TEI is a species-specific response and highlights the need to understand TEI alongside other responses to environmental variability.

evolutionary biology↗

bioRxiv2026

No preference for performance: Host plant preference, offspring performance and host plant distribution in the butterfly Aricia artaxerxes

The connection between female host plant preference and offspring performance is important for understanding how relationships between plants and phytophagous insects have evolved. According to the preference-performance hypothesis, female insects should evolve to oviposit on host plants on which offspring performance is the highest. Here, we examined the preference-performance hypothesis in the northern brown argus (Aricia artaxerxes) butterfly in the province of Uppland, Sweden, by comparing female host plant preference and larval growth between the host plant species wood cranesbill (Geranium sylvaticum) and bloody cranesbill (G. sanguineum). We also investigated if host plant preference in A. artaxerxes was related to the geographic distribution of A. artaxerxes and its host plants in the province Uppland. We found that the A. artaxerxes females, contrary to the preference-performance hypothesis, preferred ovipositing on G. sylvaticum, even though larvae feeding on G. sylvaticum were slightly smaller than those feeding on G. sanguineum. Since G. sylvaticum is more abundant and probably more utilized than G. sanguineum in Uppland, an explanation for this negative preference-performance connection may be that there are advantages associated with utilizing a more common host plant species, even though larvae feeding on this plant show reduced growth rates. Overall, the results show that factors other than offspring performance, such as geographic distribution, may influence female host plant preference in A. artaxerxes.

evolutionary biology↗

bioRxiv2023

Sex-specific growth and lifespan effects of germline removal in the dioecious nematode Caenorhabditis remanei

Germline regulates the expression of life-history traits and mediates the trade-off between reproduction and somatic maintenance. However, germline maintenance in itself can be costly, and the costs can vary between the sexes depending on the number of gametes produced across the lifetime. We tested this directly by germline ablation using glp-1 RNAi in a dioecious nematode Caenorhabditis remanei. Germline removal strongly increased heat-shock resistance in both sexes, thus confirming the role of the germline in regulating somatic maintenance. However, germline removal resulted in increased lifespan only in males. High costs of mating strongly reduced lifespan in both sexes and obliterated the survival benefit of germline-less males even though neither sex produced any offspring. Furthermore, germline removal reduced male growth before maturation but not in adulthood, while female growth rate was reduced both before and especially after maturation. Thus, germline removal improves male lifespan without major growth costs, while germline-less females grow slower and do not live longer than reproductively functional counterparts in the absence of environmental stress. Overall, these results suggest that germline maintenance is costlier for males than for females.

evolutionary biology↗

bioRxiv2023

Evolution during uncorrelated environmental fluctuations: bet-hedging or phenotypic plasticity?

Evolution in fluctuating environments is predicted to disfavor specialization and instead select for alternative strategies, such as phenotypic plasticity or possibly bet-hedging, depending on the accuracy of environmental cues and type of fluctuations. While these two alternatives are often contrasted in theoretical studies, their evolution are seldom studied together in empirical work. We used experimental evolution in the nematode worm Caenorhabditis remanei to simultaneously study the evolution of plasticity and bet-hedging in environments differing only in their temperature variability. We exposed worms for 30 generations to either fluctuating or slowly increasing temperature, these two environments had the same average temperature over evolutionary time. After experimental evolution, we scored size at sexual maturity and fitness in full siblings reared in two different temperatures, optimal 20{degrees}C and mildly stressful 25{degrees}C. Experimental evolution in the fluctuating environment resulted in the evolution of increased body size plasticity but not increased bet-hedging, compared to evolution in the slowly changing environment. Plasticity followed the temperature size rule as size decreased with increasing temperature and this plastic response was adaptive. In addition, we documented substantial standing genetic variation in body size, which represents a potential for further evolutionary change.

evolutionary biology↗

bioRxiv2021

Beneficial cumulative effects of old parental age on offspring fitness

Old parental age is commonly associated with negative effects on offspring life-history traits. Such parental effect senescence is predicted to have a cumulative detrimental effect over successive generations. However, old parents may benefit from producing high-quality offspring when these compete for seasonal resources. Thus, old parents may choose to increase investment in their offspring, thereby producing fewer but larger and more competitive progeny. We show that Caenorhabditis elegans hermaphrodites increase parental investment with advancing age, resulting in fitter offspring who reach their reproductive peak earlier. Remarkably, these effects increased over six successive generations of breeding from old parents and were subsequently reversed following a single generation of breeding from a young parent. These results contradict the theory that old parents transfer a cumulative detrimental "ageing factor" to their offspring. Instead, our findings support the hypothesis that offspring of old parents receive more resources and convert them into increasingly faster life-histories.

evolutionary biology↗

bioRxiv2020

Compensatory growth in C. elegans is regulated by a thermosensitive TRP channel and increases reproductive fitness

O_LIAnimals are often not growing at the maximum rate, but can compensate for a bad start of life by subsequently increasing growth rate. While this compensatory growth is widespread, its direct fitness consequences are seldom investigated and its genetic basis is unknown. C_LIO_LIWe investigated the genetic regulation, as well as fitness and lifespan consequences of compensatory growth in response to temperature, using C. elegans knockout of the thermo-sensitive TRP ion channel TRPA-1, involved in temperature recognition. We exposed juvenile worms to cold, favourable (intermediate) or warm temperatures in order to delay or speed up development. C_LIO_LIWild-type worms initially exposed to cold temperature experienced slower growth but after being switched to a more favourable temperature, they expressed compensatory growth and caught up in size. Those initially reared at warmer temperatures than favourable experienced slower growth and attained smaller adult size after being switched to the most favourable temperature. C_LIO_LICompensatory growth also altered the reproductive schedule. While rate-sensitive individual fitness decreased by cold juvenile temperatures, as a direct effect of the substantial developmental delay, once worms returned to more favourable temperature, they shifted their reproductive schedule towards early reproduction. Therefore, when focusing on the post-treatment period, the reproductive rate increased even though lifetime reproductive success was unaffected. Surprisingly, compensatory growth did not reduce adult lifespan. In contrast to the findings for wild-type worms, juvenile temperature did not induce compensatory or slowed-down growth in the trpa-1 knockout mutants. C_LIO_LIWe thus show that the trpa-1 is involved in the network regulating temperature-induced compensatory growth in C. elegans and that this compensatory growth can influence the reproductive rate. C_LI

evolutionary biology↗

bioRxiv2020

Variable environments select for short lifespan

The role of environmental variation in the evolution of lifespan is contested. Classic theory predicts that variable environments favour the evolution of long life, but recent theoretical work suggests that environmental variation can instead select for shorter lifespan when the changes are rapid relative to generation time. Here, we used experimental evolution to study how lifespan evolves in response to temperature variation. Genetically diverse populations of the outcrossing nematode Caenorhabditis remanei, were exposed to a novel, stressful temperature for 30 generations, under stable, gradually warming or fluctuating thermal regimes. We found the evolution of shorter lifespan in populations exposed to environments that fluctuated within the individuals lifetime, compared to populations evolving in stable warm temperature. While climate warming is predicted to increase environmental stochasticity, our results show that fast temperature cycles can rapidly select for short lifespan.

evolutionary biology↗

bioRxiv2019

Cost-free lifespan extension via optimisation of gene expression in adulthood supports the developmental theory of ageing

Classic theory upholds that energy trade-offs between reproduction and somatic maintenance underpin the evolution of ageing and lifespan. In contrast, the developmental theory of ageing (DTA) suggests that organismal senescence is caused by dysregulated gene expression in adulthood due to decline in selection gradients with age. The DTA predicts that age-specific optimisation of gene expression can improve survival without fitness costs. Here we investigated consequences for survival, reproduction, egg size and fitness of early-life, adulthood and post-reproductive onset of RNAi knockdown of five well-described \"longevity\" genes involved in key biological processes in Caenorhabditis elegans nematodes: nutrient-sensing signalling via insulin/IGF-1 (age-1) and target-of-rapamycin (raga-1) pathways, global protein synthesis (ifg-1), global protein synthesis in somatic cells (ife-2) and mitochondrial respiration (nuo-6). Downregulation of these genes in adulthood and/or during post-reproductive period improves survival, while there was little evidence for a link between impaired reproduction and extended lifespan. Our findings demonstrate that hyper-function of diverse physiological processes after sexual maturation is detrimental for survival. Therefore, optimisation of gene expression in adult organisms can ameliorate ageing and increase fitness.

evolutionary biology↗

bioRxiv2019

Kin selection and sexual conflict: male relatedness and familiarity do not affect female fitness in seed beetles

Theory maintains that kin selection can mediate sexual conflict because within-group male relatedness should reduce male-male competition, thereby reducing collateral harm to females. We tested whether male relatedness and familiarity can lessen female harm in the seed beetle Callosobruchus maculatus. Neither male relatedness nor familiarity influenced female lifetime reproductive success or individual fitness. However, male relatedness, but not familiarity, marginally improved female survival. Because male relatedness improved female survival in late life when C. maculatus females are no longer producing offspring, our results do not provide support for the role of kin selection in mediating sexual conflict. The fact that male relatedness improves the post-reproductive part of female life cycle strongly suggests that the effect is non-adaptive. We discuss adaptive and non-adaptive mechanisms that could result in reduced female harm in this and previous studies and suggest that cognitive error is a likely explanation.

evolutionary biology↗

bioRxiv2019

Environmental variation mediates the evolution of anticipatory parental effects

Theory maintains that when future environment is predictable, parents should adjust the phenotype of their offspring to match the anticipated environment. The plausibility of positive anticipatory parental effects is hotly debated and the experimental evidence for the evolution of such effects is currently lacking. We experimentally investigated the evolution of anticipatory maternal effects in a range of environments that differ drastically in how predictable they are. Populations of the nematode Caenorhabditis remanei, adapted to 20{degrees}C, were exposed to a novel temperature (25{degrees}C) for 30 generations with either positive or zero correlation between parent and offspring environment. We found that populations evolving in novel environments that were predictable across generations evolved a positive anticipatory maternal effect, since they required maternal exposure to 25{degrees}C to achieve maximum reproduction in that temperature. In contrast, populations evolving under zero environmental correlation had lost this anticipatory maternal effect. Similar but weaker patterns were found if instead rate-sensitive population growth was used as a fitness measure. These findings demonstrate that anticipatory parental effects evolve in response to environmental change so that ill-fitting parental effects can be rapidly lost. Evolution of positive anticipatory parental effects can aid population viability in rapidly changing but predictable environments. Impact summaryParents can help their offspring by adjusting offsprings phenotype to match their environment. Such anticipatory parental effects would be beneficial, but only if parents can accurately predict the environment in which their offspring will develop and live. The plausibility of such anticipatory parental effects is hotly debated. The theory is clear that the predictability of the environment should play a defining role. We used an "experimental evolution" approach in a fast reproducing nematode worm Caenorhabditis remanei to tackle this question and follow the evolution of parental effects in different environments in real-time. We found that populations evolving in a novel but predictable environment indeed had anticipatory parental effects that increased fitness of their offspring in that environment. In contrast, when evolving in an unpredictable environment where such parental effects would be disadvantageous, the parental effect was rapidly lost in evolution. Our novel experimental environments were constructed by exposing worms to increased temperature. Anticipatory parental effects play an important role in adaptation to novel environments and will affect the viability of populations under climate heating.

evolutionary biology↗

bioRxiv2019

Silver-spoon upbringing improves early-life fitness but promotes reproductive ageing in a wild bird

Early-life conditions can have long-lasting effects and organisms that experience a poor start in life are often expected to age at a faster rate. Alternatively, individuals raised in high-quality environments can overinvest in early-reproduction resulting in rapid ageing. Here we use a long-term experimental manipulation of early-life conditions in a natural population of collared flycatchers (Ficedula albicollis), to show that females raised in a low-competition environment (artificially reduced broods) have higher early-life reproduction but lower late-life reproduction than females raised in high-competition environment (artificially increased broods). Reproductive success of high-competition females peaked in late-life, when low-competition females were already in steep reproductive decline and suffered from a higher mortality rate. Our results demonstrate that "silver-spoon" natal conditions increase female early-life performance at the cost of faster reproductive ageing and increased late-life mortality. These findings demonstrate experimentally that natal environment shapes individual variation in reproductive and demographic ageing in nature.

evolutionary biology↗

bioRxiv2018

Reduced insulin/IGF-1 signalling in adult parents increases offspring fitness

Classical theory maintains that ageing evolves via energy trade-offs between reproduction and survival leading to accumulation of unrepaired cellular damage with age. In contrast, the emerging new theory postulates that ageing evolves because of deleterious late-life hyper-function of reproduction-promoting genes leading to excessive biosynthesis in late-life. The hyper-function theory uniquely predicts that optimizing nutrient-sensing molecular signalling in adulthood can simultaneously postpone ageing and increase Darwinian fitness. Here we show that reducing evolutionarily conserved insulin/IGF-1 nutrient-sensing signalling via daf-2 RNA interference (RNAi) fulfils this prediction in Caenorhabditis elegans nematodes. Long-lived daf-2 RNAi parents showed normal fecundity as self-fertilizing hermaphrodites and improved late-life reproduction when mated to males. Remarkably, the offspring of daf-2 RNAi parents had higher Darwinian fitness across three different genotypes. Thus, reduced nutrient-sensing signalling in adulthood improves both parental longevity and offspring fitness supporting the emerging view that sub-optimal gene expression in late-life lies at the heart of ageing. Impact StatementUnderstanding mechanisms underpinning ageing is fundamental to improving quality of life in an increasingly long-lived society. Recent breakthroughs have challenged the long-standing paradigm that the energy trade-off between reproduction and somatic maintenance causes organismal senescence via slow accumulation of unrepaired cellular damage with age. The emerging new theory of ageing provides a conceptually novel framework by proposing that ageing is a direct consequence of physiological processes optimized for early-life function, such as growth and early-life reproduction, that are running too high (i.e. at hyperfunction) in late adulthood. Contrary to the classic view based on damage accumulation, the hyperfunction theory proposes that suboptimal gene expression in late-life causes ageing via excessive biosynthesis. Thus, the hyperfunction theory uniquely predicts that longevity and Darwinian fitness can be simultaneously increased by reducing unnecessarily high levels of nutrient-sensing signalling in adulthood. Here we show that reducing evolutionarily conserved nutrient-sensing signalling pathway fulfils this prediction in Caenorhabditis elegans nematodes. We found that downregulation of the insulin/IGF-1 signalling in adult C. elegans nematodes not only improves longevity but, most intriguingly, increases fitness of the resulting offspring in the next generation. We found support for increase in offspring fitness across different genetic backgrounds. Our findings contradict the theoretical conjecture that energy trade-offs between growth, reproduction and longevity is the universal cause of senescence and provide strong experimental support for the emerging hyperfunction theory of ageing.

genetics↗