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1.	Amcoff, Mirjam, et al. (författare) A test of sensory exploitation in the swordtail characin (Corynopoma riisei) based on colour matchingbetween female prey and a male ornament 2014 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 97:3, s. 247-254 Tidskriftsartikel (refereegranskat)abstract The sensory exploitation hypothesis states that pre-existing biases in female sensory systems may generate strong selection on male signals to match such biases. As environmental conditions differ between populations, sexual preferences resulting from natural selection are expected to vary as well. The swordtail characin (Corynopoma riisei) is a species in which males carry a flag-like ornament growing from the operculum that has been proposed to function as a prey mimic to attract females. Here, we investigated if female plasticity in feeding preferences is associated with plasticity in preference for an artificial male ornament in this species. Females were trained for 10 days by offering them differently coloured food items and were then tested for changes in preferences for differently coloured artificial male ornaments according to foraging experience. We found a rapid and pronounced change in female preference for the colouration of the artificial ornament according to food training. Thus our results support the possibility that sensory exploitation may act as a driving force for female preferences for male ornaments in this species.
2.	Amcoff, Mirjam, et al. (författare) Courtship signalling with a labile bilateral signal : males show their best side 2009 Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 63:12, s. 1717-1725 Tidskriftsartikel (refereegranskat)abstract Asymmetries in courtship signals can result from both developmental instability during ontogeny and from temporary or permanent damage following mating, fighting, or interactions with predators. These two types of asymmetries, which can be divided into fluctuating asymmetry (FA) and damage asymmetry (DA), have both been suggested to play an important role in mate choice as potential honest indicators of phenotypic and/or genetic quality, while at the same time, DA may affect ornament asymmetry in a random manner. Interestingly, despite the massive research effort that has been devoted to the study of asymmetry during the past decades, very little is known about how an individual's behaviour relates to asymmetry. Here, we measure and characterise asymmetry in morphological courtship signals in Corynopoma riisei, a fish where males carry elaborate paddle-like appendices on each side of the body that they display in front of females during courtship. Moreover, we investigate whether male courtship display, employing this bilateral morphological trait, reflects trait asymmetry. Finally, we assess whether males respond to phenotypic manipulations of DA with corresponding changes in courtship behaviour. We show that male display behaviour is asymmetric in a manner that reflects asymmetry of their morphological courtship trait and that male display behaviour responds to manipulations of asymmetry of these paddles. Our results thus suggest that males preferentially use their best side and, hence, that males respond adaptively to temporary changes in signal trait asymmetry.
3.	Amcoff, Mirjam, et al. (författare) Does female feeding motivation affect the response to a food-mimicking male ornament in the swordtail characin Corynopoma riisei? 2013 Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 83:2, s. 343-354 Tidskriftsartikel (refereegranskat)abstract Female response to various aspects of male trait morphology and the effect of female feeding motivation were investigated in the swordtail characin Corynopoma riisei, a species where males are equipped with a flag-like food-mimicking ornament that grows from the operculum. Unfed females responded more strongly to the male ornament and showed a stronger preference for larger ornaments than did fed females. Females were shown not to discriminate between artificial male ornaments of either undamaged or damaged shape.
4.	Amcoff, Mirjam, et al. (författare) Evolution of egg dummies in Tanganyikan cichlid fishes : the roles of parental care and sexual selection 2013 Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:11, s. 2369-2382 Forskningsöversikt (refereegranskat)abstract Sexual selection has been suggested to be an important driver of speciation in cichlid fishes of the Great Lakes of Africa, and the presence of male egg dummies is proposed to have played a key role. Here, we investigate how mouthbrooding and egg dummies have evolved in Tanganyikan cichlids, the lineage which seeded the other African radiations, with a special emphasis on the egg dummies. Using modern phylogenetic comparative analyses and a phylogeny including 86% of the 200 described species, we provide formal evidence demonstrating correlated evolution between mouthbrooding and egg dummies in Tanganyikan cichlids. These results concur with existing evidence, suggesting that egg dummies have evolved through sensory exploitation. We also demonstrate that there is a strong evolutionary correlation between the presence of egg dummies and both pre- and post-copulatory sexual selection. Moreover, egg dummy evolution was contingent on the intensity of pre- and post-copulatory sexual selection in Tanganyikan cichlids. In sum, our results provide evidence supporting the hypothesis of egg dummies evolving through sensory exploitation and highlight the role of sexual selection in favouring the evolution and maintenance of this trait.
5.	Amcoff, Mirjam, 1983- (författare) Fishing for Females : Sensory Exploitation in the Swordtail Characin 2013 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Mate choice plays an important role in sexual selection and speciation. The evolution of mate choice is intriguing in cases where choosy individuals gain little except for genetic material from the mate and where the trait used as a criterion for the choice is costly to its bearer. The sensory exploitation hypothesis is an interesting idea that applies to such cases because it suggests that sexual preferences may arise as side-effects of preferences that are under selection in other contexts. The role of mate choice in speciation is strong but is debated because the reasons for population divergence in mate preferences and sexual traits are sometimes hard to explain. Also in this context sensory exploitation offers a potential explanation in that a link between natural and sexual selection may result in divergence in sexual selection whenever populations differ in natural selection.In this thesis, I test several aspects of this hypothesis in a species of fish, the swordtail characin (Corynopoma riisei). In this species males display a flag-like ornament that grows from the operculum. Because females respond to this ornament by biting at it, it has been proposed to act as a food-mimic. By manipulating female food type and quantity, and testing the resulting female preference for the male ornament, I find support for the theory that the preference has evolved through sensory exploitation and that females indeed appear to relate the ornament to a food item. Furthermore, I show that sensory exploitation can lead to morphological divergence among natural populations in this species. Apart from the flag-ornament, other courtship signals are also investigated. The results show that the relative importance of different signals may vary depending on receiver motivation. This suggests that various aspects of both male courtship signals and the conditions during which they are being signalled should be considered to gain a full understanding of mate choice and its role in sexual selection and speciation.
6.	Amcoff, Mirjam, et al. (författare) Male Courtship Pheromones Affect Female Behaviour in the Swordtail Characin ( Corynopoma riisei) 2014 Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 120:5, s. 463-470 Tidskriftsartikel (refereegranskat)abstract Pheromones constitute an important cue used by both males and females during courtship. Here, we investigate the effect of male pheromones on female behaviour in the swordtail characin (Corynopoma riisei), a species of fish where males have a caudal pheromone gland which has been suggested to affect female behaviour during courtship. We subjected female C.riisei to male courtship pheromones and investigated the effect on both female behaviour and brain serotonergic activity levels compared to a control group. While no difference in serotonergic activity was found, the pheromone-treated females showed lower stress levels compared to the control group. Furthermore, pheromone-treated females increased locomotor activity over time, while a decrease in locomotor activity was observed in the control group. These results suggest that the male courtship pheromones may serve to reduce female stress and increase female activity, possibly to aid males in gaining access to females and facilitating sperm transfer.
7.	Amcoff, Mirjam, et al. (författare) Multiple male sexual signals and female responsiveness in the swordtail characin, Corynopoma riisei 2015 Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 98:7, s. 1731-1740 Tidskriftsartikel (refereegranskat)abstract In the courtship process, multiple signals are often used between the signaller and the receiver. Here we describe female response to multiple male visual morphological and behavioural signals in the swordtail characin, Corynopoma riisei. The swordtail characin is a species in which males display several morphological ornaments as well as a rich courtship repertoire. Our results show that high courtship intensity was associated with an increased female response towards the male ornament, increased number of mating attempts and a reduction in female aggression. The morphological aspects investigated here did not seem to correlate with female response. This may indicate that, when both behaviour and morphology are considered simultaneously, courtship behaviour may have priority over morphological cues in this species.
8.	Amcoff, Mirjam, et al. (författare) Sensory exploitation and plasticity in female mate choice in the swordtail characin 2013 Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 85:5, s. 891-898 Tidskriftsartikel (refereegranskat)abstract Despite extensive research in the field of sexual selection, the evolutionary origin and maintenance of preferences for sexual ornaments are still debated. Recent studies have pointed out that plasticity in mate choice might be more common than previously thought, but little is still known about the factors that affect such plasticity. The swordtail characin, Corynopoma riisei, is a tropical fish species in which males use a food-mimicking ornament to attract females. We tested whether ecological factors, more specifically prior foraging experience, can affect female preference for male ornaments. For this, we habituated females on a diet consisting of either red-coloured food or standard-coloured green food items and then we tested whether female preferences for artificially red-coloured male ornaments matched their previous foraging experience. We found a strong effect of food treatment: females trained on red food showed a stronger response to males with red-coloured ornaments than females trained on green food. Our results show that ecological variation can generate divergence of female preferences for male ornaments and that the response in preference to environmental change can be rapid if the bias is partly learnt.
9.	Boussard, Annika, et al. (författare) Brain size does not predict learning strategies in a serial reversal learning test 2020 Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 223:15 Tidskriftsartikel (refereegranskat)abstract Reversal learning assays are commonly used across a wide range of taxa to investigate associative learning and behavioural flexibility. In serial reversal learning, the reward contingency in a binary discrimination is reversed multiple times. Performance during serial reversal learning varies greatly at the interspecific level, as some animals adopt a rule-based strategy that enables them to switch quickly between reward contingencies. A larger relative brain size, generating enhanced learning ability and increased behavioural flexibility, has been proposed to be an important factor underlying this variation. Here, we experimentally tested this hypothesis at the intraspecific level. We used guppies (Poecilia reticulata) artificially selected for small and large relative brain size, with matching differences in neuron number, in a serial reversal learning assay. We tested 96 individuals over 10 serial reversals and found that learning performance and memory were predicted by brain size, whereas differences in efficient learning strategies were not. We conclude that variation in brain size and neuron number is important for variation in learning performance and memory, but these differences are not great enough to cause the larger differences in efficient learning strategies observed at higher taxonomic levels.
10.	Boussard, Annika, et al. (författare) The link between relative brain size and cognitive ageing in female guppies (Poecilia reticulata) artificially selected for variation in brain size 2021 Ingår i: Experimental Gerontology. - : Elsevier BV. - 0531-5565 .- 1873-6815. ; 146 Tidskriftsartikel (refereegranskat)abstract Cognitive ageing is the general process when certain mental skills gradually deteriorate with age. Across species, there is a pattern of a slower brain structure degradation rate in large-brained species. Hence, having a larger brain might buffer the impact of cognitive ageing and positively affect survival at older age. However, few studies have investigated the link between relative brain size and cognitive ageing at the intraspecific level. In particular, experimental data on how brain size affects brain function also into higher age is largely missing. We used 288 female guppies (Poecilia reticulata), artificially selected for large and small relative brain size, to investigate variation in colour discrimination and behavioural flexibility, at 4-6, 12 and 24 months of age. These ages are particularly interesting since they cover the life span from sexual maturation until maximal life length under natural conditions. We found no evidence for a slower cognitive ageing rate in large-brained females in neither initial colour discrimination nor reversal learning. Behavioural flexibility was predicted by large relative brain size in the youngest group, but the effect of brain size disappeared with increasing age. This result suggests that cognitive ageing rate is faster in large-brained female guppies, potentially due to the faster ageing and shorter lifespan in the large-brained selection lines. It also means that cognition levels align across different brain sizes with older age. We conclude that there are cognitive consequences of ageing that vary with relative brain size in advanced learning abilities, whereas fundamental aspects of learning can be maintained throughout the ecologically relevant life span.
11.	Fong, Stephanie, 1990-, et al. (författare) Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (Poecilia reticulata) Annan publikation (övrigt vetenskapligt/konstnärligt)abstract The vertebrate brain displays enormous morphological variation and the quest to understand the evolutionary causes and consequences of this variation has spurred over a century of research. The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently, is a highly influential idea in this research field. Here we provide the first experimental support for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After three generations of selection on relative telencephalon volume in replicated up-selected, down-selected and control selection lines, we found substantial overall changes in relative telencephalon size (i.e. relative to brain size), but no changes in other brain regions. The differences were not evident at birth but present at the time of sexual maturation. There was a non-significant trend towards asymmetry in the response to selection in both sexes, with larger changes occurring during upwards selection as opposed to downwards selection. Our results demonstrate that independent evolutionary changes in specific brain regions can be an important mechanism during cognitive evolution.
12.	Fong, Stephanie, et al. (författare) Rapid mosaic brain evolution under artificial selection for relative telencephalon size in the guppy (Poecilia reticulata) 2021 Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 7:46 Tidskriftsartikel (refereegranskat)abstract The mosaic brain evolution hypothesis, stating that brain regions can evolve relatively independently during cognitive evolution, is an important idea to understand how brains evolve with potential implications even for human brain evolution. Here, we provide the first experimental evidence for this hypothesis through an artificial selection experiment in the guppy (Poecilia reticulata). After four generations of selection on relative telencephalon volume (relative to brain size), we found substantial changes in telencephalon size but no changes in other regions. Further comparisons revealed that up-selected lines had larger telencephalon, while down-selected lines had smaller telencephalon than wild Trinidadian populations. Our results support that independent evolutionary changes in specific brain regions through mosaic brain evolution can be important facilitators of cognitive evolution.
13.	Fong, Stephanie, et al. (författare) Relative telencephalon size does not affect boldness in the guppy (Poecilia reticulata) Annan publikation (övrigt vetenskapligt/konstnärligt)abstract It has long been acknowledged that individuals consistently differ in their behaviour over time and across contexts, often defined as animal personality. Much of the existing research into personality traits in animals have focussed on the bold-shy continuum, given its implications in fitness and relatively straight-forward quantification. Recently, a substantial research effort has focussed on how brain morphology affects the level of boldness. Using recently established artificial selection lines with known differences in telencephalon size, a brain region important for decision making, we tested this potential link with a test battery for boldness (emergence test, open field test and novel object test). We did not detect an effect of telencephalon size on overall level of boldness. However, supporting previous findings we found a strong sex-difference in behavioural patterns whereby male guppies were generally more active and more likely to emerge from the start compartment, presumably due to different life-history strategies. Our results thus do not support any direct link between the size of the telencephalon and boldness at the intraspecific level.
14.	Jutfelt, Fredrik, et al. (författare) Brain cooling marginally increases acute upper thermal tolerance in Atlantic cod 2019 Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 222:19 Tidskriftsartikel (refereegranskat)abstract Physiological mechanisms determining thermal limits in fishes are debated but remain elusive. It has been hypothesised that motor function loss, observed as loss of equilibrium during acute warming, is due to direct thermal effects on brain neuronal function. To test this, we mounted cooling plates on the heads of Atlantic cod (Gadus morhua) and quantified whether local brain cooling increased whole-organism acute upper thermal tolerance. Brain cooling reduced brain temperature by 2-6 °C below ambient water temperature and increased thermal tolerance by 0.5 and 0.6 °C on average relative to instrumented and uninstrumented controls, respectively, suggesting that direct thermal effects on brain neurons may contribute to setting upper thermal limits in fish. However, the improvement in thermal tolerance with brain cooling was small relative to the difference in brain temperature, demonstrating that other mechanisms (e.g. failure of spinal and peripheral neurons, or muscle) may also contribute to controlling acute thermal tolerance.
15.	Kolm, Niclas, et al. (författare) Diversification of a Food-Mimicking Male Ornament via Sensory Drive 2012 Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 22:15, s. 1440-1443 Tidskriftsartikel (refereegranskat)abstract The evolutionary divergence of sexual signals is often important during the formation of new animal species, but our understanding of the origin of signal diversity is limited [1, 2]. Sensory drive, the optimization of communication signal efficiency through matching to the local environment, has been highlighted as a potential promoter of diversification and speciation [3]. The swordtail characin (Corynopoma riisei) is a tropical fish in which males display a flag-like ornament that elicits female foraging behavior during courtship. We show that the shape of the male ornament covaries with female diet across natural populations. More specifically, natural populations in which the female diet is more dominated by ants exhibit male ornaments more similar to the shape of an ant. Feeding experiments confirm that females habituated to a diet of ants prefer to bite at male ornaments from populations with a diet more dominated by ants. Our results show that the male ornament functions as a "fishing lure" that is diversifying in shape to match local variation in female search images employed during foraging. This direct link between variation in female feeding ecology and the evolutionary diversification of male sexual ornaments suggests that sensory drive may be a common engine of signal divergence.
16.	Kotrschal, Alexander, et al. (författare) A larger brain confers a benefit in a spatial mate search learning task in male guppies 2015 Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 26:2, s. 527-532 Tidskriftsartikel (refereegranskat)abstract Brain size varies dramatically among vertebrates, and selection for increased cognitive abilities is thought to be the key force underlying the evolution of a large brain. Indeed, numerous comparative studies suggest positive relationships between cognitively demanding aspects of behavior and brain size controlled for body size. However, experimental evidence for the link between relative brain size and cognitive ability is surprisingly scarce and to date stems from a single study on brain size selected guppies (Poecilia reticulata), where large-brained females were shown to outperform small-brained females in a numerical learning assay. Because the results were inconclusive for males in that study, we here use a more ecologically relevant test of male cognitive ability to investigate whether or not a relatively larger brain increases cognitive ability also in males. We compared mate search ability of these artificially selected large-and small-brained males in a maze and found that large-brained males were faster at learning to find a female in a maze. Large-brained males decreased the time spent navigating the maze faster than small-brained males and were nearly twice as fast through the maze after 2 weeks of training. Our results support that relatively larger brains are better also for males in some contexts, which further substantiates that variation in vertebrate brain size is generated through the balance between energetic costs and cognitive benefits.
17.	Liao, Sifang, et al. (författare) Impact of high-fat diet on lifespan, metabolism, fecundity and behavioral senescence in Drosophila 2021 Ingår i: Insect Biochemistry and Molecular Biology. - : Elsevier BV. - 0965-1748 .- 1879-0240. ; 133 Tidskriftsartikel (refereegranskat)abstract Excess consumption of high-fat diet (HFD) is likely to result in obesity and increases the predisposition to associated health disorders. Drosophila melanogaster has emerged as an important model to study the effects of HFD on metabolism, gut function, behavior, and ageing. In this study, we investigated the effects of HFD on physiology and behavior of female flies at different time-points over several weeks. We found that HFD decreases lifespan, and also with age leads to accelerated decline of climbing ability in both virgins and mated flies. In virgins HFD also increased sleep fragmentation with age. Furthermore, long-term exposure to HFD results in elevated adipokinetic hormone (AKH) transcript levels and an enlarged crop with increased lipid stores. We detected no long-term effects of HFD on body mass, or levels of triacylglycerides (TAG), glycogen or glucose, although fecundity was diminished. However, one week of HFD resulted in decreased body mass and elevated TAG levels in mated flies. Finally, we investigated the role of AKH in regulating effects of HFD during aging. Both with normal diet (ND) and HFD, Akh mutant flies displayed increased longevity compared to control flies. However, both mutants and controls showed shortened lifespan on HFD compared to ND. In flies exposed to ND, fecundity is decreased in Akh mutants compared to controls after one week, but increased after three weeks. However, HFD leads to a similar decrease in fecundity in both genotypes after both exposure times. Thus, long-term exposure to HFD increases AKH signaling, impairs lifespan and fecundity and augments age-related behavioral senescence.
18.	Norin, Tommy, et al. (författare) Predator presence affects activity patterns but not food consumption or growth of juvenile corkwing wrasse (Symphodus melops) 2021 Ingår i: Behavioral Ecology and Sociobiology. - : Springer. - 0340-5443 .- 1432-0762. ; 75:1 Tidskriftsartikel (refereegranskat)abstract Indirect effects of predators can manifest themselves as changes in prey behaviour and physiology. Given that digestion requires energy, it has been suggested that prey will choose to eat smaller meals under predation risk to reserve a larger portion of the aerobic metabolic scope they have available for energetically demanding tasks more critical than digestion, such as escape. To test this prediction, we quantified food consumption and growth of juvenile corkwing wrasses (Symphodus melops) over 11 days in the presence or absence of a predator (Atlantic cod, Gadus morhua). We then quantified behaviour and food consumption of the same wrasses in behavioural arenas with a predator. All food consumption was examined in the context of the aerobic scope that would have been available during the digestive period. Overall, there was no effect of predator exposure on food consumption or growth, yet predator-exposed wrasses were more consistent in their daily food consumption, lending some support to our prediction of prey bet-hedging on meal size under predation risk. The lack of a clear pattern may have resulted from a relatively low percentage of aerobic scope (similar to 20-27%) being occupied by digestion, such that fish retained ample capacity for activities other than digestion. In the subsequent behavioural trials, predator-exposed wrasses were more active and spent more time near the cod than predator-naive wrasses, suggesting the former had habituated to predation threat and were more risk-taking. Our results highlight the complex and often counter-intuitive effects that predator presence can have on prey populations beyond direct consumption. Significance statement Predators affect the behaviour of prey species by simply being present in the environment. Such intimidation by predators can change activity patterns of prey and be as important as direct predation for ecosystem dynamics. However, compared to behavioural changes, we know little about how predators indirectly affect prey physiology. We investigated if fish deliberately eat less food when a predator is present, in order to retain sufficient physiological capacity for avoiding a potential attack, on top of the energetically costly process of digesting. While our study confirms that predator encounters reduce prey activity, prey fish appeared to rapidly habituate to predator presence and we did not see reduced food consumption in predator-exposed fish; these were, however, more consistent than unexposed fish in their daily food consumption, suggesting that fish may still be mindful about protecting their aerobic capacity under predation risk.
19.	Roche, Dominique G., et al. (författare) Behavioural lateralization in a detour test is not repeatable in fishes 2020 Ingår i: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 167, s. 55-64 Tidskriftsartikel (refereegranskat)abstract Behavioural lateralization, the asymmetric expression of cognitive functions, is reported to enhance key fitness-relevant traits such as group coordination, multitasking and predator escape. Therefore, studies reporting negative effects on lateralization in fish due to environmental stressors such as ocean acidification, hypoxia and pollutants are worrisome. However, such studies tend to use a detour test and focus on population level measures, without validating whether lateralization is consistent within individuals across time. We conducted a multispecies, international assessment of the repeatability (R) of lateralization in four previously studied fish species using a detour test (T-maze), a common method for testing lateralization. We also reanalysed a published data set on a fifth species using new statistical methods. We expected the three shoaling species to exhibit greater within-individual consistency in lateralization than their nonshoaling counterparts given previous reports of stronger lateralization in group-living fishes. Absolute and relative lateralization scores were highly nonrepeatable in all five species (0.01<R<0.08), irrespective of their shoaling status. We carefully reviewed 31 published studies in which the detour test was employed to examine lateralization in fish and identified statistical issues in all of them. We develop and propose new statistical analyses to test for population and individual level lateralization. The commonly used detour test does not appear to be appropriate for quantifying behavioural lateralization in fishes, calling into question functional inferences drawn by many published studies, including our own. Potential fitness benefits of lateralization and anthropogenic effects on lateralization as a proxy for adaptive brain functioning need to be assessed with alternative paradigms.
20.	Rodrigues, Leonor R., et al. (författare) Fluctuating heat stress during development exposes reproductive costs and putative benefits 2022 Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 91:2, s. 391-403 Tidskriftsartikel (refereegranskat)abstract Temperature and thermal variability are increasing worldwide, with well-known survival consequences. However, effects on other potentially more thermally sensitive reproductive traits are less understood, especially when considering thermal variation. Studying the consequences of male reproduction in the context of climate warming and ability to adapt is becoming increasingly relevant.Our goals were to test how exposure to different average temperatures that either fluctuated or remained constant impacts different male reproductive performance traits and to assess adaptive potential to future heat stress.We took advantage of a set of Drosophila melanogaster isogenic lines of different genotypes, exposing them to four different thermal conditions. These conditions represented a benign and a stressful mean temperature, applied either constantly or fluctuating around the mean and experienced during development when heat stress avoidance is hindered because of restricted mobility. We measured subsequent male reproductive performance for mating success, fertility, number of offspring produced and offspring sex ratio, and calculated the influence of thermal stress on estimated heritability and evolvability of these reproductive traits.Both costs and benefits to different thermal conditions on reproductive performance were found, with some responses varying between genotypes. Mating success improved under fluctuating benign temperature conditions and declined as temperature stress increased regardless of genotype. Fertility and productivity were severely reduced at fluctuating mean high temperature for all genotypes, but some genotypes were unaffected at constant high mean temperature. These more thermally robust genotypes showed a slight increase in productivity under the fluctuating benign condition compared to constant high temperature, despite both thermal conditions sharing the same temperature for 6 hr daily. Increasing thermal stress resulted in higher heritability and evolvability.Overall, the effects of temperature on reproductive performance depended on the trait and genotype; performance of some traits slightly increased when high temperatures were experienced for short periods but decreased substantially even when experiencing a benign temperature for a portion of each day. While thermal stress increased genetic variation that could provide adaptive potential against climate warming, this is unlikely to compensate for the overall severe negative effect on reproductive performance as mean temperature and variance increase.
21.	Sundin, Josefin, et al. (författare) Long-term acclimation to near-future ocean acidification has negligible effects on energetic attributes in a juvenile coral reef fish 2019 Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 190:3, s. 689-702 Tidskriftsartikel (refereegranskat)abstract Increased levels of dissolved carbon dioxide (CO2) drive ocean acidification and have been predicted to increase the energy use of marine fishes via physiological and behavioural mechanisms. This notion is based on a theoretical framework suggesting that detrimental effects on energy use are caused by plasma acid-base disruption in response to hypercapnic acidosis, potentially in combination with a malfunction of the gamma aminobutyric acid type A (GABA(A)) receptors in the brain. However, the existing empirical evidence testing these effects primarily stems from studies that exposed fish to elevated CO2 for a few days and measured a small number of traits. We investigated a range of energetic traits in juvenile spiny chromis damselfish (Acanthochromis polyacanthus) over 3months of acclimation to projected end-of-century CO2 levels (similar to 1000 mu atm). Somatic growth and otolith size and shape were unaffected by the CO2 treatment across 3months of development in comparison with control fish (similar to 420 mu atm). Swimming activity during behavioural assays was initially higher in the elevated CO2 group, but this effect dissipated within similar to 25min following handling. The transient higher activity of fish under elevated CO2 was not associated with a detectable difference in the rate of oxygen uptake nor was it mediated by GABA(A) neurotransmitter interference because treatment with a GABA(A) antagonist (gabazine) did not abolish the CO2 treatment effect. These findings contrast with several short-term studies by suggesting that end-of-century levels of CO2 may have negligible direct effects on the energetics of at least some species of fish.
22.	Sundin, Josefin, 1981-, et al. (författare) Long-term exposure to elevated carbon dioxide does not alter activity levels of a coral reef fish in response to predator chemical cues 2017 Ingår i: Behavioral Ecology and Sociobiology. - : SPRINGER. - 0340-5443 .- 1432-0762. ; 71:8 Tidskriftsartikel (refereegranskat)abstract Levels of dissolved carbon dioxide (CO2) projected to occur in the world's oceans in the near future have been reported to increase swimming activity and impair predator recognition in coral reef fishes. These behavioral alterations would be expected to have dramatic effects on survival and community dynamics in marine ecosystems in the future. To investigate the universality and replicability of these observations, we used juvenile spiny chromis damselfish (Acanthochromis polyacanthus) to examine the effects of long-term CO 2 exposure on routine activity and the behavioral response to the chemical cues of a predator (Cephalopholis urodeta). Commencing at similar to 3-20 days post-hatch, juvenile damselfish were exposed to presentday CO2 levels (similar to 420 mu atm) or to levels forecasted for the year 2100 (similar to 1000 mu atm) for 3 months of their development. Thereafter, we assessed routine activity before and after injections of seawater (sham injection, control) or seawater-containing predator chemical cues. There was no effect of CO2 treatment on routine activity levels before or after the injections. All fish decreased their swimming activity following the predator cue injection but not following the sham injection, regardless of CO2 treatment. Our results corroborate findings from a growing number of studies reporting limited or no behavioral responses of fishes to elevated CO2. Significance statement Alarmingly, it has been reported that levels of dissolved carbon dioxide (CO2) forecasted for the year 2100 cause coral reef fishes to be attracted to the chemical cues of predators. However, most studies have exposed the fish to CO2 for very short periods before behavioral testing. Using long-term acclimation to elevated CO2 and automated tracking software, we found that fish exposed to elevated CO2 showed the same behavioral patterns as control fish exposed to present-day CO2 levels. Specifically, activity levels were the same between groups, and fish acclimated to elevated CO2 decreased their swimming activity to the same degree as control fish when presented with cues from a predator. These findings indicate that behavioral impacts of elevated CO2 levels are not universal in coral reef fishes.
23.	Sundin, Josefin, 1981-, et al. (författare) Males show their best side revisited : Effects of predation pressure on laterality in wild guppies 2023 Ingår i: Ethology. - : Wiley-VCH Verlagsgesellschaft. - 0179-1613 .- 1439-0310. ; 129:8, s. 390-405 Tidskriftsartikel (refereegranskat)abstract The ability to detect and avoid predators has been suggested as one of the main drivers for behavioral lateralization. This is supported by studies reporting that animals from high-predation environments are more lateralized than those from low-predation environments. Some studies, however, have shown no effect of predator regime on lateralization. Lateralized behavior can also be driven by phenotypic asymmetry, where the more attractive side of the body is preferentially displayed during male-female interaction and courtship. The importance of fluctuating asymmetry for mate choice has been highly debated for a number of reasons. Here, we revisited the concepts of predator-induced behavioral lateralization and phenotypic asymmetry using wild Trinidadian guppies Poecilia reticulata from three different stream systems. Using fish collected from both high- and low-predation environments, we quantified behavioral lateralization in terms of directional turning bias, measured right-left body color asymmetry, and investigated whether a male side-showing preference was present in male-female interaction trials. We found that guppies were, at best, moderately lateralized on average (across all populations), without any general effect of predator regime. There were some slight stream-dependent side biases in color asymmetry, but this did not translate into a side-showing preference in any of the populations in the interaction trials. Some significant observed effects align with previously published results, but these were dependent on stream-origin and were not repeated across different experiments, complicating interpretation. We conclude that when investigating the effects of predation regime in general, and such effects on behavioral lateralization or fluctuating asymmetry in particular, attention must be focused toward several factors such as experimental assay used and population origin, and broad generalizations from results stemming from experiments including only one population should be avoided.
24.	Triki, Zegni, et al. (författare) Artificial mosaic brain evolution of relative telencephalon size improves inhibitory control abilities in the guppy (Poecilia reticulata) 2022 Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 76:1, s. 128-138 Tidskriftsartikel (refereegranskat)abstract Mosaic brain evolution, the change in the size of separate brain regions in response to selection on cognitive performance, is an important idea in the field of cognitive evolution. However, untill now, most of the data on how separate brain regions respond to selection and their cognitive consequences stem from comparative studies. To experimentally investigate the influence of mosaic brain evolution on cognitive ability, we used male guppies artificially selected for large and small telencephalons relative to the rest of the brain. Here, we tested an important aspect of executive cognitive ability using a detour task. We found that males with larger telencephalons outperformed males with smaller telencephalons. Fish with larger telencephalons showed faster improvement in performance during detour training and were more successful in reaching the food reward without touching the transparent barrier (i.e., through correct detouring) during the test phase. Together, our findings provide the first experimental evidence showing that evolutionary enlargement of relative telencephalon size confers cognitive benefits, supporting an important role for mosaic brain evolution during cognitive evolution.
25.	Triki, Zegni, et al. (författare) Brain morphology correlates of learning and cognitive flexibility in a fish species (Poecilia reticulata) 2022 Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 289:1978 Tidskriftsartikel (refereegranskat)abstract Determining how variation in brain morphology affects cognitive abilities is important to understand inter-individual variation in cognition and, ultimately, cognitive evolution. Yet, despite many decades of research in this area, there is surprisingly little experimental data available from assays that quantify cognitive abilities and brain morphology in the same individuals. Here, we tested female guppies (Poecilia reticulata) in two tasks, colour discrimination and reversal learning, to evaluate their learning abilities and cognitive flexibility. We then estimated the size of five brain regions (telencephalon, optic tectum, hypothalamus, cerebellum and dorsal medulla), in addition to relative brain size. We found that optic tectum relative size, in relation to the rest of the brain, correlated positively with discrimination learning performance, while relative telencephalon size correlated positively with reversal learning performance. The other brain measures were not associated with performance in either task. By evaluating how fast learning occurs and how fast an animal adjusts its learning rules to changing conditions, we find support for that different brain regions have distinct functional correlations at the individual level. Importantly, telencephalon size emerges as an important neural correlate of higher executive functions such as cognitive flexibility. This is rare evidence supporting the theory that more neural tissue in key brain regions confers cognitive benefits.
26.	Triki, Zegni, 1984-, et al. (författare) Experimental expansion of relative telencephalon size improves the main executive function abilities in guppy 2023 Ingår i: PNAS Nexus. - 2752-6542. ; 2:6 Tidskriftsartikel (refereegranskat)abstract Executive functions are a set of cognitive control processes required for optimizing goal-directed behavior. Despite more than two centuries of research on executive functions, mostly in humans and nonhuman primates, there is still a knowledge gap in what constitutes the mechanistic basis of evolutionary variation in executive function abilities. Here, we show experimentally that size changes in a forebrain structure (i.e. telencephalon) underlie individual variation in executive function capacities in a fish. For this, we used male guppies (Poecilia reticulata) issued from artificial selection lines with substantial differences in telencephalon size relative to the rest of the brain. We tested fish from the up- and down-selected lines not only in three tasks for the main core executive functions: cognitive flexibility, inhibitory control, and working memory, but also in a basic conditioning test that does not require executive functions. Individuals with relatively larger telencephalons outperformed individuals with smaller telencephalons in all three executive function assays but not in the conditioning assay. Based on our findings, we propose that the telencephalon is the executive brain in teleost fish. Together, it suggests that selective enlargement of key brain structures with distinct functions, like the fish telencephalon, is a potent evolutionary pathway toward evolutionary enhancement of advanced cognitive abilities in vertebrates.
27.	Zandawala, Meet, et al. (författare) A neuroendocrine pathway modulating osmotic stress in Drosophila 2021 Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 17:3 Tidskriftsartikel (refereegranskat)abstract Environmental factors challenge the physiological homeostasis in animals, thereby evoking stress responses. Various mechanisms have evolved to counter stress at the organism level, including regulation by neuropeptides. In recent years, much progress has been made on the mechanisms and neuropeptides that regulate responses to metabolic/nutritional stress, as well as those involved in countering osmotic and ionic stresses. Here, we identified a peptidergic pathway that links these types of regulatory functions. We uncover the neuropeptide Corazonin (Crz), previously implicated in responses to metabolic stress, as a neuroendocrine factor that inhibits the release of a diuretic hormone, CAPA, and thereby modulates the tolerance to osmotic and ionic stress. Both knockdown of Crz and acute injections of Crz peptide impact desiccation tolerance and recovery from chill-coma. Mapping of the Crz receptor (CrzR) expression identified three pairs of Capa-expressing neurons (Va neurons) in the ventral nerve cord that mediate these effects of Crz. We show that Crz acts to restore water/ion homeostasis by inhibiting release of CAPA neuropeptides via inhibition of cAMP production in Va neurons. Knockdown of CrzR in Va neurons affects CAPA signaling, and consequently increases tolerance for desiccation, ionic stress and starvation, but delays chill-coma recovery. Optogenetic activation of Va neurons stimulates excretion and simultaneous activation of Crz and CAPA-expressing neurons reduces this response, supporting the inhibitory action of Crz. Thus, Crz inhibits Va neurons to maintain osmotic and ionic homeostasis, which in turn affects stress tolerance. Earlier work demonstrated that systemic Crz signaling restores nutrient levels by promoting food search and feeding. Here we additionally propose that Crz signaling also ensures osmotic homeostasis by inhibiting release of CAPA neuropeptides and suppressing diuresis. Thus, Crz ameliorates stress-associated physiology through systemic modulation of both peptidergic neurosecretory cells and the fat body in Drosophila.

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