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An often-overlooked aspect of life-history optimization is the allocation of resources to protect the germline and secure safe transmission of genetic information. While failure to do so renders significant fitness consequences in future generations, germline maintenance comes with substantial costs. Thus, germline allocation should trade off with other life-history decisions and be optimized in accordance with an organism's reproductive schedule. Here, we tested this hypothesis by studying germline maintenance in lines of seed beetle, selected for early (E) or late (L) reproduction for 350 and 240 generations, respectively. Female animals provide maintenance and screening of male gametes in their reproductive tract and oocytes. Here, we reveal the ability of young and aged E- and L-females to provide this form of germline maintenance by mating them to males with ejaculates with artificially elevated levels of protein and DNA damage. We find that germline maintenance in E-females peaks at young age and then declines, while the opposite is true for L-females, in accordance with the age of reproduction in the respective regime. These findings identify the central role of allocation to secure germline integrity in life-history evolution and highlight how females can play a crucial role in mitigating the effects of male germline decisions on mutation rate and offspring quality. [ABSTRACT FROM AUTHOR]

Critical thermal limits (CTLs) gauge the physiological impact of temperature on survival or critical biological function, aiding predictions of species range shifts and climatic resilience. Two recent Drosophila species studies, using similar approaches to determine temperatures that induce sterility (thermal fertility limits [TFLs]), reveal that TFLs are often lower than CTLs and that TFLs better predict both current species distributions and extinction probability. Moreover, many studies show fertility is more sensitive at less extreme temperatures than survival (thermal sensitivity of fertility [TSF]). These results present a more pessimistic outlook on the consequences of climate change. However, unlike CTLs, TFL data are limited to Drosophila , and variability in TSF methods poses challenges in predicting species responses to increasing temperature. To address these data and methodological gaps, we propose 3 standardized approaches for assessing thermal impacts on fertility. We focus on adult obligate sexual terrestrial invertebrates but also provide modifications for other animal groups and life-history stages. We first outline a "gold-standard" protocol for determining TFLs, focussing on the effects of short-term heat shocks and simulating more frequent extreme heat events predicted by climate models. As this approach may be difficult to apply to some organisms, we then provide a standardized TSF protocol. Finally, we provide a framework to quantify fertility loss in response to extreme heat events in nature, given the limitations in laboratory approaches. Applying these standardized approaches across many taxa, similar to CTLs, will allow robust tests of the impact of fertility loss on species responses to increasing temperatures. [ABSTRACT FROM AUTHOR]

Climates are changing rapidly, demanding equally rapid adaptation of natural populations. Whether sexual selection can aid such adaptation is under debate; while sexual selection should promote adaptation when individuals with high mating success are also best adapted to their local surroundings, the expression of sexually selected traits can incur costs. Here we asked what the demographic consequences of such costs may be once climates change to become harsher and the strength of natural selection increases. We first adopted a classic life history theory framework, incorporating a trade-off between reproduction and maintenance, and applied it to the male germline to generate formalized predictions for how an evolutionary history of strong postcopulatory sexual selection (sperm competition) may affect male fertility under acute adult heat stress. We then tested these predictions by assessing the thermal sensitivity of fertility (TSF) in replicated lineages of seed beetles maintained for 68 generations under three alternative mating regimes manipulating the opportunity for sexual and natural selection. In line with the theoretical predictions, we find that males evolving under strong sexual selection suffer from increased TSF. Interestingly, females from the regime under strong sexual selection, who experienced relaxed selection on their own reproductive effort, had high fertility in benign settings but suffered increased TSF, like their brothers. This implies that female fertility and TSF evolved through genetic correlation with reproductive traits sexually selected in males. Paternal but not maternal heat stress reduced offspring fertility with no evidence for adaptive transgenerational plasticity among heat-exposed offspring, indicating that the observed effects may compound over generations. Our results suggest that trade-offs between fertility and traits increasing success in postcopulatory sexual selection can be revealed in harsh environments. This can put polyandrous species under immediate risk during extreme heat waves expected under future climate change. [ABSTRACT FROM AUTHOR]

Predicting if, when, and how populations can adapt to climate change constitutes one of the greatest challenges in science today. Here, we build from contributions to the special issue on evolutionary adaptation to climate change, a survey of its authors, and recent literature to explore the limits and opportunities for predicting adaptive responses to climate change. We outline what might be predictable now, in the future, and perhaps never even with our best efforts. More accurate predictions are expected for traits characterized by a well-understood mapping between genotypes and phenotypes and traits experiencing strong, direct selection due to climate change. A meta-analysis revealed an overall moderate trait heritability and evolvability in studies performed under future climate conditions but indicated no significant change between current and future climate conditions, suggesting neither more nor less genetic variation for adapting to future climates. Predicting population persistence and evolutionary rescue remains uncertain, especially for the many species without sufficient ecological data. Still, when polled, authors contributing to this special issue were relatively optimistic about our ability to predict future evolutionary responses to climate change. Predictions will improve as we expand efforts to understand diverse organisms, their ecology, and their adaptive potential. Advancements in functional genomic resources, especially their extension to non-model species and the union of evolutionary experiments and "omics," should also enhance predictions. Although predicting evolutionary responses to climate change remains challenging, even small advances will reduce the substantial uncertainties surrounding future evolutionary responses to climate change. [ABSTRACT FROM AUTHOR]

Background: Systemic AA amyloidosis is a world-wide occurring protein misfolding disease in humans and animals that arises from the formation of amyloid fibrils from serum amyloid A (SAA) protein and their deposition in multiple organs. Objective: To identify new agents that prevent fibril formation from SAA protein and to determine their mode of action. Materials and Methods: We used a cell model for the formation of amyloid deposits from SAA protein to screen a library of peptides and small proteins, which were purified from human hemofiltrate. To clarify the inhibitory mechanism the obtained inhibitors were characterised in cell-free fibril formation assays and other biochemical methods. Results: We identified lysozyme as an inhibitor of SAA fibril formation. Lysozyme antagonised fibril formation both in the cell model as well as in cell-free fibril formation assays. The protein binds SAA with a dissociation constant of 16.5 ± 0.6 mM, while the binding site on SAA is formed by segments of positively charged amino acids. Conclusion: Our data imply that lysozyme acts in a chaperone-like fashion and prevents the aggregation of SAA protein through direct, physical interactions. [ABSTRACT FROM AUTHOR]

Male animals often show higher mutation rates than their female conspecifics. A hypothesis for this male bias is that competition over fertilization of female gametes leads to increased male investment into reproduction at the expense of maintenance and repair, resulting in a trade-off between male success in sperm competition and offspring quality. Here, we provide evidence for this hypothesis by harnessing the power of experimental evolution to study effects of sexual selection on the male germline in the seed beetle Callosobruchus maculatus. We first show that 50 generations of evolution under strong sexual selection, coupled with experimental removal of natural selection, resulted in males that are more successful in sperm competition. We then show that these males produce progeny of lower quality if engaging in sociosexual interactions prior to being challenged to surveil and repair experimentally induced damage in their germline and that the presence of male competitors alone can be enough to elicit this response. We identify 18 candidate genes that showed differential expression in response to the induced germline damage, with several of these previously implicated in processes associated with DNA repair and cellular maintenance. These genes also showed significant expression changes across sociosexual treatments of fathers and predicted the reduction in quality of their offspring, with expression of one gene also being strongly correlated to male sperm competition success. Sex differences in expression of the same 18 genes indicate a substantially higher female investment in germline maintenance. While more work is needed to detail the exact molecular underpinnings of our results, our findings provide rare experimental evidence for a trade-off between male success in sperm competition and germline maintenance. This suggests that sex differences in the relative strengths of sexual and natural selection are causally linked to male mutation bias. The tenet advocated here, that the allocation decisions of an individual can affect plasticity of its germline and the resulting genetic quality of subsequent generations, has several interesting implications for mate choice processes. In many species, males' sperm compete for fertilization of eggs inside the female reproductive tract. This study of seed beetles suggests that the increased male investment in such sperm competition may lead to reduced genetic quality in future generations. [ABSTRACT FROM AUTHOR]

Systemic AL amyloidosis arises from the misfolding of patient-specific immunoglobulin light chains (LCs). Potential drivers of LC amyloid formation are mutational changes and post-translational modifications (PTMs). However, little information is available on the exact primary structure of the AL proteins and their precursor LCs. We analyse the exact primary structure of AL proteins extracted from 10 λ AL amyloidosis patients and their corresponding precursor LCs. By cDNA sequencing of the precursor LC genes in combination with mass spectrometry of the AL proteins, the exact primary structure and PTMs were determined. This information was used to analyse their biochemical properties. All AL proteins comprise the VL and a small part of the CL with a common C-terminal truncation region. While all AL proteins retain the conserved native disulphide bond of the VL, we found no evidence for presence of other common PTMs. The analysis of the biochemical properties revealed that the isoelectric point of the VL is significantly increased due to introduced mutations. Our data imply that mutational changes influence the surface charge properties of the VL and that common proteolytic processes are involved in the generation of the cleavage sites of AL proteins. [ABSTRACT FROM AUTHOR]

Lysozyme-derived (ALys) amyloidosis is a rare type of hereditary amyloidosis. Nine amyloidogenic variants and ∼30 affected families have been described worldwide. The most common manifestations are renal dysfunction, gastrointestinal tract symptoms, and sicca syndrome. We report on the clinical course of ten patients from six families representing one of the largest cohorts published so far. Seven patients carried the W64R variant showing the whole spectrum of ALys-associated symptoms. Two patients—a mother-son pair—carried a novel lysozyme variant, which was associated with nephropathy and peripheral polyneuropathy. In accordance with previous findings, the phenotype resembled within these families but did not correlate with the genotype. To gain insights into the effect of the variants at the molecular level, we analysed the structure of lysozyme and performed comparative computational predictions on aggregation propensity and conformational stability. Our study supports that decreased conformational stability is a key factor for lysozyme variants to be prone to aggregation. In summary, ALys amyloidosis is a very rare, but still heterogeneous disease that can manifest at an early age. Our newly identified lysozyme variant is associated with nephropathy and peripheral polyneuropathy. Further research is needed to understand its pathogenesis and to enable the development of new treatments. [ABSTRACT FROM AUTHOR]

To mitigate the effects of climate change, it is important to understand species' responses to increasing temperatures. This has often been done by studying survival or activity at temperature extremes. Before such extremes are reached, however, effects on fertility may already be apparent.Sex differences in the thermal sensitivity of fertility (TSF) could impact species persistence under climate warming because female fertility is typically more limiting to population growth than male fertility. However, little is known about sex differences in TSF.Here we first demonstrate that the mating system can strongly influence TSF using the seed beetle Callosobruchus maculatus. We exposed populations carrying artificially induced mutations to two generations of short‐term experimental evolution under alternative mating systems, manipulating the opportunity for natural and sexual selection on the mutations. We then measured TSF in males and females subjected to juvenile or adult heat stress.Populations kept under natural and sexual selection had higher fitness, but similar TSF, compared to control populations kept under relaxed selection. However, females had higher TSF than males, and strikingly, this sex difference had increased over only two generations in populations evolving under sexual selection.We hypothesized that an increase in male‐induced harm to females during mating had played a central role in driving this evolved sex difference, and indeed, remating under conditions limiting male harassment of females reduced both male and female TSF. Moreover, we show that manipulation of mating system parameters in C. maculatus generates intraspecific variation in the sex difference in TSF equal to that found among a diverse set of studies on insects.Our study provides a causal link between the mating system and TSF. Sexual conflict, (re)mating rates and genetic responses to sexual selection differ among ecological settings, mating systems and species. Our study therefore also provides mechanistic understanding for the variability in previously reported TSFs which can inform future experimental assays and predictions of species responses to climate warming. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Adaptation in new environments depends on the amount of genetic variation available for evolution, and the efficacy by which natural selection discriminates among this variation. However, whether some ecological factors reveal more genetic variation, or impose stronger selection pressures than others, is typically not known. Here, we apply the enzyme kinetic theory to show that rising global temperatures are predicted to intensify natural selection throughout the genome by increasing the effects of DNA sequence variation on protein stability. We test this prediction by (i) estimating temperature-dependent fitness effects of induced mutations in seed beetles adapted to ancestral or elevated temperature, and (ii) calculate 100 paired selection estimates on mutations in benign versus stressful environments from unicellular and multicellular organisms. Environmental stress per se did not increase mean selection on de novo mutation, suggesting that the cost of adaptation does not generally increase in new ecological settings to which the organism is maladapted. However, elevated temperature increased the mean strength of selection on genome-wide polymorphism, signified by increases in both mutation load and mutational variance in fitness. These results have important implications for genetic diversity gradients and the rate and repeatability of evolution under climate change. [ABSTRACT FROM AUTHOR]

Organismal life histories evolve as syndromes, resulting in correlated evolutionary differentiation of key traits that ultimately aid in discerning species. Reproductive success depends both on the absolute body size of an individual and its size relative to the opposite sex: sexual size dimorphism. In an attempt to further elucidate their coexistence and ecological diversification, we compared standard life history (first reproduction, clutch size, egg size) and associated reproductive trait differentiation of 15 widespread European sepsid fly species (Diptera: Sepsidae) under laboratory common garden conditions. Despite relatively uniform body sizes, sexual dimorphism ranged from female‐ to male‐biased, and development time varied twofold across species. We expected, and found, the abundant and relatively large species (Sepsis cynipsea, punctum, thoracica) with often male‐biased SSD to lay larger but fewer eggs and show fast‐developing, fast‐reproducing life histories with aggressive (coercive) mating behavior characterized by short mating latencies and male conflict. In contrast, the smaller and more dispersed species with female‐biased SSD (S. flavimana, orthocnemis, violacea) laid smaller but more eggs, showing a generally slower life history with long and delayed copulation and oviposition, high mating reluctance fostering extensive inter‐sexual conflict, and more elaborate male (pre‐)copulatory courtship. Two Saltella species were exceptional, being large, developing slowly, nevertheless copulating soon after adult emergence, profusely and briefly. The documented life history differentiation seems partly driven by sexual selection leading to male‐biased dimorphism, rather than undetermined ecological selection, but regardless appears insufficient to explain the coexistence and diversification of these sepsid species in European pastoral landscapes. [ABSTRACT FROM AUTHOR]

Sexual selection represents a potent force that can drive rapid population differentiation in traits related to reproductive success. Hence, sexual traits are expected to show greater population divergence than non‐sexual traits. We test this prediction by exploring patterns of morphological differentiation of the exaggerated fore femur (a male‐specific sexual trait) and the wing (a non‐sexual trait) among allopatric and sympatric populations of the widespread sister dung fly species Sepsis neocynipsea and Sepsis cynipsea (Diptera: Sepsidae). While both species occur in Eurasia, S. neocynipsea also abounds in North America, albeit previous studies suggest strong differentiation in morphology, behavior, and mating systems. To evaluate the degree of differentiation expected under neutrality between S. cynipsea, European S. neocynipsea, and North American S. neocynipsea, we genotyped 30 populations at nine microsatellite markers, revealing almost equal differentiation between and minor differentiation among geographic populations within the three lineages. Landmark‐based analysis of 18 populations reared at constant 18 and 24°C in a laboratory common garden revealed moderate temperature‐dependent phenotypic plasticity and significant heritable differentiation in size and shape of male forelegs and wings among iso‐female lines of the three lineages. Following the biological species concept, there was weaker differentiation between cross‐continental populations of S. neocynipsea relative to S. cynipsea, and more fore femur differentiation between the two species in sympatry versus allopatry (presumably due to character displacement). Contrary to expectation, wing morphology showed as much shape differentiation between evolutionary independent lineages as fore femora, providing no evidence for faster diversification of traits primarily engaged in mating. [ABSTRACT FROM AUTHOR]

Microbial electrosynthesis or electro‐fermentation in bioelectrochemical systems (BES) have recently received much attention. Here, we demonstrate with the glycerol metabolism by Clostridium pasteurianum that H 2 from in situ water electrolysis, especially in combination with a redox mediator, provides a simple and flexible way for shifting product selectivity and enhancing product yield in the fermentation process. In particular, we report and quantify for the first time strictly different effects of Neutral Red (NR) and the barely studied redox mediator Brilliant Blue (BB) on the growth and product formation of C. pasteurianum grown on glycerol in a newly developed BES. We were able to switch the product formation pattern of C. pasteurianum with a concentration‐dependent addition of NR and BB under varied iron availability. Interestingly, NR and BB influenced the glycerol metabolism in a strictly opposite manner concerning the formation of the major products 1,3‐propanediol (1,3‐PDO) and n‐butanol (BuOH). Whereas, NR and iron generally enhance the formation of BuOH, BB favors the formation of 1,3‐PDO. In BES the metabolic shifts were enhanced, leading to a further increased yield by as high as 33% for BuOH in NR fermentations and 21% for 1,3‐PDO in BB fermentations compared with the respective controls. For the first time, the electron transfer mediated by these mediators and their recycle (recharge) were unambiguously quantified by excluding the overlapping effect of iron. BB has a higher capacity than NR and iron. The extra electron transfer by BB can account for as high as 30–75% of the total NAD + regeneration under certain conditions, contributing significantly to the product formation. [ABSTRACT FROM AUTHOR]

Lianas are an important structural component of tropical rain forests. Recent concern regarding a putative global rise in liana abundance, and its implications for forest conservation, calls for data collection across biomes. We here provide a first assessment and baseline data for a geographical gap in liana surveys to date. We surveyed liana (diameter at breast height [DBH] > 1 cm), tree (DBH > 10 cm) and sapling (DBH ≤ 10 cm) abundance and basal area, as well as liana–host relationships, in a tropical East African primary forest. We recorded a total of 347 liana stems (DBH > 1 cm) in 0.31 ha, with an average basal area of 1.21 m2/ha. Lianas were found to be widespread, with 24% of saplings and 57% of trees colonised by at least one liana, independently of bark texture or host diameter. The dominant liana colonisation strategy was to associate with a single host, through stem twining. We found no evidence of liana density being influenced by host density. We synthesised published liana density data across continents and report that our estimate of liana density for Kibale's primary forest fits within the expected range of liana densities for primary tropical forests. This synthesis further highlights a neotropical sampling bias, which our findings make a step towards addressing. [ABSTRACT FROM AUTHOR]

Predicting if, when, and how populations can adapt to climate change constitutes one of the greatest challenges in science today. Here, we build from contributions to the special issue on evolutionary adaptation to climate change, a survey of its authors, and recent literature to explore the limits and opportunities for predicting adaptive responses to climate change. We outline what might be predictable now, in the future, and perhaps never even with our best efforts. More accurate predictions are expected for traits characterized by a well-understood mapping between genotypes and phenotypes and traits experiencing strong, direct selection due to climate change. A meta-analysis revealed an overall moderate trait heritability and evolvability in studies performed under future climate conditions but indicated no significant change between current and future climate conditions, suggesting neither more nor less genetic variation for adapting to future climates. Predicting population persistence and evolutionary rescue remains uncertain, especially for the many species without sufficient ecological data. Still, when polled, authors contributing to this special issue were relatively optimistic about our ability to predict future evolutionary responses to climate change. Predictions will improve as we expand efforts to understand diverse organisms, their ecology, and their adaptive potential. Advancements in functional genomic resources, especially their extension to non-model species and the union of evolutionary experiments and "omics," should also enhance predictions. Although predicting evolutionary responses to climate change remains challenging, even small advances will reduce the substantial uncertainties surrounding future evolutionary responses to climate change., Competing Interests: The authors declare no conflicts of interest. A.C., M.S., A.E., and C.T. are associate editors or special issue guest editors of Evolution Letters. Editorial processing of the manuscript was done independently of these editors., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE) and European Society for Evolutionary Biology (ESEN).)

Climates are changing rapidly, demanding equally rapid adaptation of natural populations. Whether sexual selection can aid such adaptation is under debate; while sexual selection should promote adaptation when individuals with high mating success are also best adapted to their local surroundings, the expression of sexually selected traits can incur costs. Here we asked what the demographic consequences of such costs may be once climates change to become harsher and the strength of natural selection increases. We first adopted a classic life history theory framework, incorporating a trade-off between reproduction and maintenance, and applied it to the male germline to generate formalized predictions for how an evolutionary history of strong postcopulatory sexual selection (sperm competition) may affect male fertility under acute adult heat stress. We then tested these predictions by assessing the thermal sensitivity of fertility (TSF) in replicated lineages of seed beetles maintained for 68 generations under three alternative mating regimes manipulating the opportunity for sexual and natural selection. In line with the theoretical predictions, we find that males evolving under strong sexual selection suffer from increased TSF. Interestingly, females from the regime under strong sexual selection, who experienced relaxed selection on their own reproductive effort, had high fertility in benign settings but suffered increased TSF, like their brothers. This implies that female fertility and TSF evolved through genetic correlation with reproductive traits sexually selected in males. Paternal but not maternal heat stress reduced offspring fertility with no evidence for adaptive transgenerational plasticity among heat-exposed offspring, indicating that the observed effects may compound over generations. Our results suggest that trade-offs between fertility and traits increasing success in postcopulatory sexual selection can be revealed in harsh environments. This can put polyandrous species under immediate risk during extreme heat waves expected under future climate change., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Society for the Study of Evolution (SSE) and European Society for Evolutionary Biology (ESEN).)

Adaptation in new environments depends on the amount of genetic variation available for evolution, and the efficacy by which natural selection discriminates among this variation. However, whether some ecological factors reveal more genetic variation, or impose stronger selection pressures than others, is typically not known. Here, we apply the enzyme kinetic theory to show that rising global temperatures are predicted to intensify natural selection throughout the genome by increasing the effects of DNA sequence variation on protein stability. We test this prediction by (i) estimating temperature-dependent fitness effects of induced mutations in seed beetles adapted to ancestral or elevated temperature, and (ii) calculate 100 paired selection estimates on mutations in benign versus stressful environments from unicellular and multicellular organisms. Environmental stress per se did not increase mean selection on de novo mutation, suggesting that the cost of adaptation does not generally increase in new ecological settings to which the organism is maladapted. However, elevated temperature increased the mean strength of selection on genome-wide polymorphism, signified by increases in both mutation load and mutational variance in fitness. These results have important implications for genetic diversity gradients and the rate and repeatability of evolution under climate change.

Sexual selection is generally held responsible for the exceptional diversity in secondary sexual traits in animals. Mating system evolution is therefore expected to profoundly affect the covariation between secondary sexual traits and mating success. Whereas there is such evidence at the interspecific level, data within species remain scarce. We here investigate sexual selection acting on the exaggerated male fore femur and the male wing in the common and widespread dung flies Sepsis punctum and S. neocynipsea (Diptera: Sepsidae). Both species exhibit intraspecific differences in mating systems and variation in sexual size dimorphism (SSD) across continents that correlates with the extent of male-male competition. We predicted that populations subject to increased male-male competition will experience stronger directional selection on the sexually dimorphic male foreleg. Our results suggest that fore femur size, width and shape were indeed positively associated with mating success in populations with male-biased SSD in both species, which was not evident in conspecific populations with female-biased SSD. However, this was also the case for wing size and shape, a trait often assumed to be primarily under natural selection. After correcting for selection on overall body size by accounting for allometric scaling, we found little evidence for independent selection on any of these size or shape traits in legs or wings, irrespective of the mating system. Sexual dimorphism and (foreleg) trait exaggeration is therefore unlikely to be driven by direct precopulatory sexual selection, but more so by selection on overall size or possibly selection on allometric scaling., (© 2019 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2019 European Society For Evolutionary Biology.)