| 1. |
- Friberg, Magne, et al.
(författare)
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Heterospecific courtship, minority effects and niche separation between cryptic butterfly species
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:5, s. 971-979
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Tidskriftsartikel (refereegranskat)abstract
- Species interacting in varied ecological conditions often evolve in different directions in different local populations. The butterflies of the cryptic Leptidea complex are sympatrically distributed in different combinations across their Eurasian range. Interestingly, the same species is a habitat generalist in some regions and a habitat specialist in others, where a sibling species has the habitat generalist role. Previous studies suggest that this geographically variable niche divergence is generated by local processes in different contact zones. By varying the absolute and relative densities of Leptidea sinapis and Leptidea juvernica in large outdoor cages, we show that female mating success is unaffected by conspecific density, but strongly negatively affected by the density of the other species. Whereas 80% of the females mated when a conspecific couple was alone in a cage, less than 10% mated when the single couple shared the cage with five pairs of the other species. The heterospecific courtships can thus affect the population fitness, and for the species in the local minority, the suitability of a habitat is likely to depend on the presence or absence of the locally interacting species. If the local relative abundance of the different species depends on the colonization order, priority effects might determine the ecological roles of interacting species in this system.
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| 2. |
- Friberg, Magne, et al.
(författare)
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Heterospecific courtships, Allee-effects and niche separation between Leptidea sinapis and Leptidea reali
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Annan publikation (populärvet., debatt m.m.)abstract
- Increasing attention is given to coevolutionary studies and to the role of ecology in local adaptation. The coevolutionary process can act in parallel throughout the distribution of species that interact in similar ecologies, whereas species interacting in varied ecological conditions might coevolve in different directions in different local populations. The butterflies Leptidea sinapis and L. reali have partitioned their niches differently in different parts of their sympatric distribution, with one species being a local habitat generalist in several different regions, and a local specialist in other areas where the sister species has adopted the habitat generalist role. Niche separation is likely independent of resource competition in this phytophagous system, and we study the potential for heterospecific sexual interference competition to redefine the suitability of a habitat and select for niche separation. We used the average female mating success in large outdoor cage experiments that varied both the absolute and relative density of the two species to estimate potential fitness costs of being in local minority. The mating success was unaffected by absolute density (conspecifics/m2) but strongly affected by the proportion of con- and heterospecifics in each cage. The proportion of mated females was ten times higher when a conspecific couple spent the day alone in the cage compared to when the single couple shared the cage with five heterospecific pairs. Being in the minority thus resulted in strong sexual interference from the locally more common competitor. We propose that these Allee effects select for habitat specialisation in the locally rare species as individuals leaving the core population likely suffer decreased fitness from spending time in heterospecific courtship. Hence, habitat suitability might depend less on local resource availability and more on the presence or absence of a local sexual competitor in this system.
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| 3. |
- Kazemi, Baharan, et al.
(författare)
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Learning of salient prey traits explains Batesian mimicry evolution
- 2018
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 72:3, s. 531-539
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Tidskriftsartikel (refereegranskat)abstract
- Batesian mimicry evolution involves an initial major mutation that produces a rough resemblance to the model, followed by smaller improving changes. To examine the learning psychology of this process, we applied established ideas about mimicry in Papilio polyxenes asterius of the model Battus philenor. We performed experiments with wild birds as predators and butterfly wings as semiartificial prey. Wings of hybrids of P. p. asterius and Papilio machaon were used to approximate the first mutant, with melanism as the hypothesized first mimetic trait. Based on previous results about learning psychology and imperfect mimicry, we predicted that: melanism should have high salience (i.e., being noticeable and prominent), meaning that predators readily discriminate a melanistic mutant from appearances similar to P. machaon; the difference between the first mutant and the model should have intermediate salience to allow further improvement of mimicry; and the final difference in appearance between P. p. asterius and B. philenor should have very low salience, causing improvement to level off. Our results supported both the traditional hypothesis and all our predictions about relative salience. We conclude that there is good agreement between long-held ideas about how Batesian mimicry evolves and recent insights from learning psychology about the role of salience in mimicry evolution.
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| 4. |
- Kivelä, Sami M., et al.
(författare)
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Towards a mechanistic understanding of insect life history evolution : oxygen-dependent induction of moulting explains moulting sizes
- 2016
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 117:3, s. 586-600
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Tidskriftsartikel (refereegranskat)abstract
- Moults characterise insect growth trajectories, typically following a consistent pattern known as Dyar's rule; proportional size increments remain constant across inter-instar moults. Empirical work suggests that oxygen limitation triggers moulting. The insect respiratory system, and its oxygen supply capacity, grows primarily at moults. It is hypothesized that the oxygen demand increases with increasing body mass, eventually meeting the oxygen supply capacity at an instar-specific critical mass where moulting is triggered. Deriving from this hypothesis, we develop a novel mathematical model for moulting and growth in insect larvae. Our mechanistic model has great success in predicting moulting sizes in four butterfly species, indirectly supporting a size-dependent mechanism underlying moulting. The results demonstrate that an oxygen-dependent induction of moulting mechanism would be sufficient to explain moulting sizes in the study species. Model predictions deviated slightly from Dyar's rule, the deviations being typically negligible within the present data range. The developmental decisions (e.g. moulting) made by growing larvae significantly affect age and size at maturity, which has important life history implications. The successful modelling of moulting presented here provides a novel framework for the development of realistic insect growth models, which are required for a better understanding of life history evolution.
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| 5. |
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| 6. |
- Stålhandske, Sandra, 1986-, et al.
(författare)
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Phenological matching rather than genetic variation in host preference underlies geographical variation in host plants used by the orange tip butterflies
- 2016
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 119:4, s. 1060-1067
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Tidskriftsartikel (refereegranskat)abstract
- An insect species that shows variation in host species association across its geographical range may do so either because of local adaptation in host plant preference of the insect, or through environmentally or genetically induced differences in the plants, causing variation in host plant suitability between regions. Here we experimentally investigate host plant preference of Anthocharis cardamines (orange tip butterfly) of two populations from UK and two from Sweden. Previous reports indicate that A. cardamines larvae are found on different host plant species in different regions of the United Kingdom, and some variation has been reported in Sweden. Host plant choice trials showed that females prefer to oviposit on plants in an earlier phenological stage, as well as on larger plants. When controlling for plant phenological stage and size, the host species had no statistically significant effect on the choice of the females. Moreover, there were no differences in host plant species preference among the four butterfly populations. Based on our experiment, the oviposition choice by A. cardamines mainly depends on the phenological stage and the size of the host plant. This finding supports the idea that the geographical patterns of host-plant association of A. cardamines in the UK and Sweden are consequences of the phenology and availability of local hosts, rather than regional genetic differences in host species preference of the butterfly.
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