| 1. |
- Blanckenhorn, Wolf U, et al.
(författare)
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Proximate causes of Rensch's rule : Does sexual size dimorphism in arthropods result from sex differences in development time?
- 2007
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Ingår i: American Naturalist. ; 169:2, s. 245-257
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Tidskriftsartikel (refereegranskat)abstract
- A prominent interspecific pattern of sexual size dimorphism (SSD) is Rensch's rule, according to which male body size is more variable or evolutionarily divergent than female body size. Assuming equal growth rates of males and females, SSD would be entirely mediated, and Rensch's rule proximately caused, by sexual differences in development times, or sexual bimaturism (SBM), with the larger sex developing for a proportionately longer time. Only a subset of the seven arthropod groups investigated in this study exhibits Rensch's rule. Furthermore, we found only a weak positive relationship between SSD and SBM overall, suggesting that growth rate differences between the sexes are more important than development time differences in proximately mediating SSD in a wide but by no means comprehensive range of arthropod taxa. Except when protandry is of selective advantage ( as in many butterflies, Hymenoptera, and spiders), male development time was equal to ( in water striders and beetles) or even longer than ( in drosophilid and sepsid flies) that of females. Because all taxa show female-biased SSD, this implies faster growth of females in general, a pattern markedly different from that of primates and birds (analyzed here for comparison). We discuss three potential explanations for this pattern based on life-history trade-offs and sexual selection.
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| 2. |
- Cassel, Anna, et al.
(författare)
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Effects of population size and food stress on fitness-related characters in the scarce heath, a rare butterfly in Western Europe
- 2001
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Ingår i: Conservation Biology. - : Blackwell Science Publishing. - 0888-8892 .- 1523-1739. ; 15:6, s. 1667-1673
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Knowledge about the effects of inbreeding in natural populations is scarce, especially in invertebrates. We analyzed to what extent fitness-related traits in the scarce heath ( Coenonympha hero), a butterfly, are affected by population size and isolation and whether differences in food quality influence these effects. We categorized nine populations as either large or small and isolated. Full-sib groups of offspring from 27 females were followed under seminatural conditions. Because of increased zygote mortality, egg hatchability was significantly lower in the small and isolated populations than in the large ones. Population category had no effect on larval weight under optimal conditions, but weight was significantly lower in the small-isolated category with low food quality. The effects of inbreeding can thus be hidden when conditions are benign but can appear under stress. Survival also differed significantly between population categories, and larval developmental time tended to be longer in the small-isolated category, irrespective of food conditions. We suggest that the differences in fitness between offspring from large and small isolated populations are at least partly due to inbreeding. This adds a further threat to a species that is already suffering from decreasing population sizes and increasing isolation among populations.
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| 3. |
- Gotthard, Karl, et al.
(författare)
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Individual state controls temperature dependence in a butterfly (Lasiommata maera)
- 2000
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 267:1443, s. 589-93
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Tidskriftsartikel (refereegranskat)abstract
- In ectotherms there is typically a strong and positive correlation between growth rate and ambient temperature when food is not limiting. However, the exact relationship between growth rate and temperature varies among populations in many species. As a consequence, it has been suggested that selection for a rapid increase in growth rate with temperature should be stronger in populations experiencing a high degree of time-stress, compared with populations experiencing little time-stress. In the present study we take this adaptive hypothesis further and investigate if variation in time-stress among individuals of a single population may affect the relationship between growth rate and ambient temperature. Time-stress was manipulated by rearing larvae of the butterfly Lasiommata maera in different day-length regimes. The results show that individuals experiencing a higher degree of time-stress increase their growth rates more in higher temperatures compared with individuals under less time-stress. Hence, the adaptive hypothesis was supported and the relationship between growth rate and temperature was highly state dependent. These findings may be of general importance for understanding the evolution of life histories in seasonal environments.
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| 4. |
- Hill, Jason, et al.
(författare)
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Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution
- 2019
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:6
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Tidskriftsartikel (refereegranskat)abstract
- Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.
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| 5. |
- Larsdotter-Mellström, Helena, et al.
(författare)
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It's All in the Mix : Blend-Specific Behavioral Response to a Sexual Pheromone in a Butterfly
- 2016
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Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Among insects, sexual pheromones are typically mixtures of two to several components, all of which are generally required to elicit a behavioral response. Here we show for the first time that a complete blend of sexual pheromone components is needed to elicit a response also in a butterfly. Males of the Green-veined White, Pieris napi, emit an aphrodisiac pheromone, citral, from wing glands. This pheromone is requisite for females to accept mating with a courting male. Citral is a mixture of the two geometric isomers geranial (E-isomer) and neral (Z-isomer) in an approximate 1:1 ratio. We found that both these compounds are required to elicit acceptance behavior, which indicates synergistic interaction between processing of the isomers. Using functional Ca2+ imaging we found that geranial and neral evoke significantly different but overlapping glomerular activity patterns in the antennal lobe, which suggests receptors with different affinity for the two isomers. However, these glomeruli were intermingled with glomeruli responding to, for example, plant-related compounds, i.e., no distinct subpopulation of pheromone-responding glomeruli as in moths and other insects. In addition, these glomeruli showed lower specificity than pheromone-activated glomeruli in moths. We could, however, not detect any mixture interactions among four identified glomeruli, indicating that the synergistic effect may be generated at a higher processing level. Furthermore, correlations between glomerular activity patterns evoked by the single isomers and the blend did not change over time.
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| 6. |
- Lehmann, Philipp, et al.
(författare)
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Energy and lipid metabolism during direct and diapause development in a pierid butterfly
- 2016
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 219:19, s. 3049-3060
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Tidskriftsartikel (refereegranskat)abstract
- Diapause is a fundamental component of the life-cycle in the majority of insects living in environments characterized by strong seasonality. The present study addresses poorly understood associations and trade-offs between endogenous diapause duration, thermal sensitivity of development, energetic cost of development and cold tolerance. Diapause intensity, metabolic rate trajectories and lipid profiles of directly developing and diapausing animals were studied using pupae and adults of Pieris napi butterflies from a population for which endogenous diapause is well studied. Endogenous diapause was terminated after 3 months and termination required chilling. Metabolic and postdiapause development rates increased with diapause duration, while the metabolic cost of postdiapause development decreased, indicating that once diapause is terminated development proceeds at a low rate even at low temperature. Diapausing pupae had larger lipid stores than the directly developing pupae and lipids constituted the primary energy source during diapause. However, during diapause lipid stores did not decrease. Thus, despite lipid catabolism meeting the low energy costs of the diapausing pupae, primary lipid store utilization did not occur until the onset of growth and metamorphosis in spring. In line with this finding, diapausing pupae contained low amounts of mitochondria-derived cardiolipins, which suggests a low capacity for fatty acid β-oxidation. While ontogenic development had a large effect on lipid and fatty acid profiles, only small changes in these were seen during diapause. The data therefore indicate that the diapause lipidomic phenotype is built early, when pupae are still at high temperature, and retained until diapause post-diapause development.
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| 7. |
- Lehmann, Philipp, et al.
(författare)
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Metabolome dynamics of diapause in the butterfly Pieris napi: Distinguishing maintenance, termination and post-diapause phases
- 2018
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 1477-9145 .- 0022-0949. ; 221:2
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Tidskriftsartikel (refereegranskat)abstract
- Diapause is a deep resting stage facilitating temporal avoidance of unfavourable environmental conditions, and is used by many insects to adapt their life cycle to seasonal variation. Although considerable work has been invested in trying to understand each of the major diapause stages (induction, maintenance and termination), we know very little about the transitions between stages, especially diapause termination. Understanding diapause termination is crucial for modelling and predicting spring emergence and winter physiology of insects, including many pest insects. In order to gain these insights, we investigated metabolome dynamics across diapause development in pupae of the butterfly Pieris napi, which exhibits adaptive latitudinal variation in the length of endogenous diapause that is uniquely well characterized. By employing a time-series experiment, we show that the whole-body metabolome is highly dynamic throughout diapause and differs between pupae kept at a diapause-terminating (low) temperature and those kept at a diapause-maintaining (high) temperature. We show major physiological transitions through diapause, separate temperature-dependent from temperature-independent processes and identify significant patterns of metabolite accumulation and degradation. Together, the data show that although the general diapause phenotype (suppressed metabolism, increased cold tolerance) is established in a temperature-independent fashion, diapause termination is temperature dependent and requires a cold signal. This revealed several metabolites that are only accumulated under diapause-terminating conditions and degraded in a temperatureunrelated fashion during diapause termination. In conclusion, our findings indicate that some metabolites, in addition to functioning as cryoprotectants, for example, are candidates for having regulatory roles as metabolic clocks or time-keepers during diapause.
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| 8. |
- Nielsen, Matthew, et al.
(författare)
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Evolution of butterfly seasonal plasticity driven by climate change varies across life stages
- 2023
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Ingår i: Ecology Letters. - 1461-023X .- 1461-0248. ; 26:9, s. 1548-1558
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Tidskriftsartikel (refereegranskat)abstract
- Photoperiod is a common cue for seasonal plasticity and phenology, but climate change can create cue-environment mismatches for organisms that rely on it. Evolution could potentially correct these mismatches, but phenology often depends on multiple plastic decisions made during different life stages and seasons that may evolve separately. For example, Pararge aegeria (Speckled wood butterfly) has photoperiod-cued seasonal life history plasticity in two different life stages: larval development time and pupal diapause. We tested for climate change-associated evolution of this plasticity by replicating common garden experiments conducted on two Swedish populations 30 years ago. We found evidence for evolutionary change in the contemporary larval reaction norm-although these changes differed between populations-but no evidence for evolution of the pupal reaction norm. This variation in evolution across life stages demonstrates the need to consider how climate change affects the whole life cycle to understand its impacts on phenology.
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