| 1. |
- Abbott, Jessica, et al.
(författare)
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Correlated morphological and colour differences among females of the damselfly Ischnura elegans
- 2009
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Ingår i: Ecological Entomology. - : Wiley. - 1365-2311 .- 0307-6946. ; 34:3, s. 378-386
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Tidskriftsartikel (refereegranskat)abstract
- 1. The female-limited colour polymorphic damselfly Ischnura elegans has proven to be an interesting study organism both as an example of female sexual polymorphism, and in the context of the evolution of colour polymorphism, as a model of speciation processes. 2. Previous research suggests the existence of correlations between colour morph and other phenotypic traits, and the different female morphs in I. elegans may be pursuing alternative phenotypically integrated strategies. However, previous research on morphological differences in southern Swedish individuals of this species was only carried out on laboratory-raised offspring from a single population, leaving open the question of how widespread such differences are. 3. The present study therefore analysed multi-generational data from 12 populations, investigating morphological differences between the female morphs in the field, differences in the pattern of phenotypic integration between morphs, and quantified selection on morphological traits. 4. It was found that consistent morphological differences indeed existed between the morphs across populations, confirming that the previously observed differences were not simply a laboratory artefact. It was also found, somewhat surprisingly, that despite the existence of sexual dimorphism in body size and shape, patterns of phenotypic integration differed most between the morphs and not between the sexes. Finally, linear selection gradients showed that female morphology affected fecundity differently between the morphs. 5. We discuss the relevance of these results to the male mimicry hypothesis and to the existence of potential ecological differences between the morphs.
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| 2. |
- Kumschick, Sabrina, et al.
(författare)
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Determinants of local ant (Hymenoptera: Formicidae) species richness and activity density across Europe
- 2009
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Ingår i: Ecological Entomology. - : Wiley. - 1365-2311 .- 0307-6946. ; 34:6, s. 748-754
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Tidskriftsartikel (refereegranskat)abstract
- 1. Species richness is influenced by local habitat features and large-scale climatic gradients. Usually, both influences are studied in isolation because of the divergent spatial scales at which they occur. Here, we compared the influence of large-scale climate and local habitat type on European ants using a continent-wide, standardised sampling programme. 2. We investigated species richness and activity density from pitfall traps distributed over four habitat types at 17 locations from northern Sweden to Spain and Greece. Species richness and activity density were analysed with respect to ambient energy [equilibrium evapotranspiration (EET)] and productive energy (net primary productivity). Furthermore, we compared ant richness and activity density between the four habitat types: arable land, scrubland, grassland, and forest. 3. Species richness and activity density of ants increased with equilibrium evapotranspiration (EET), explaining 30.2% of the total variation in species richness and 24.2% of activity density. Habitat type explained an additional 19.2% of the variation in species richness and 20.2% of activity density, and was not related to productivity. Species richness and activity density were highest in scrubland and significantly lower in forest and (marginally significant) in arable land. 4. The increase in EET and the decrease in forest confirms the pronounced thermophily of ants, whereas the decrease in arable land is probably caused by soil disturbance.
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| 3. |
- Larsson, Magnus, et al.
(författare)
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Estimating the population size of specialised solitary bees
- 2008
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 33:2, s. 232-238
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Tidskriftsartikel (refereegranskat)abstract
- 1. Reliable methods for quantifying population size are crucial for strategies to conserve endangered wild-bee species. Estimates of population size obtained through survey walks were compared with estimates obtained through mark–recapture studies in 10 populations of the red-listed solitary bee Andrena hattorfiana in southern Sweden. 2. The mean number of bees observed during survey walks was strongly correlated with estimates of population size obtained with mark–recapture. It was found that 5.5–23.4% (mean 13.4%) of the total population was observed during an average survey walk. 3. One component in mark–recapture analysis is the measure of survival of individuals. In the largest bee population, females of A. hattorfiana that emerged in early season were found to forage for pollen on average 18.4 days. 4. The findings suggest that during large-scale surveys, for example re-inventories for red-listed species, the population size of solitary bees can be quantified reliably and effectively by performing survey walks in a two-step process. The first step consists of survey walks to establish the relationship between number of bee observations per survey walk and mark–recapture population size for a small set of populations. In the second, simple observation survey walks can be performed for a large set of populations. In each population of A. hattorfiana, it is recommended that at least six survey walks are performed.
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| 4. |
- Albrectsen, Benedicte, et al.
(författare)
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Does the differential seedling mortality caused by slugs alter the foliar traits and subsequent susceptibility of hybrid willows to a generalist herbivore?
- 2007
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 32, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- Abstract. 1. Many Salicaceae species naturally form hybrid swarms with parental and hybrid taxa that differ in secondary chemical profile and in resistance to herbivores. Theoretically, the differential mortality in the seedling stage can lead to changes in trait expression and alter subsequent interactions between plants and herbivores. This study examines whether herbivory by the generalist slug Arion subfuscus, which causes extensive mortality in young willow seedlings, causes shifts in (a) the foliar chemistry of F2 willow hybrids (Salix sericea and Salix eriocephala), and (b) the subsequent susceptibility to Japanese Beetles, Popillia japonica.2. In 2001, two populations of F2 seedlings were generated: those that survived slug herbivory (80–90% of seedlings placed in the field were killed by the slugs) were designated as S-plants, whereas C-plants (controls) experienced no mortality.3. Common garden experiments with cuttings from these populations, in 2001 and 2002, revealed extensive variation in the phenolic chemistry of F2 hybrids, but revealed no significant difference between S- and C-plants, although the levels of foliar nutrients, proteins and nitrogen tended to be higher in S-plants.4. Concentrations of salicortin and 2'-cinnamoylsalicortin explained 55 and 38% of the the variation in leaf damage caused by Japanese beetles, and secondary chemistry was highly correlated within replicate clones (salicortin R2 = 0.85, 2-cinnamoylsalicortin R2 = 0.77, condensed tannins R2 = 0.68).5. Interestingly, Japanese beetle damage and condensed tannins were positively correlated within the S-plants, but not in the C-plants, suggesting that slugs had selected for plants with a positive relationship between tannins and P. japonica damage. This is unlikely to be a consequence of a preference for tannins, but is suggested to be related to the elevated nutrient levels in the S-plants, perhaps in combination with the complex-binding properties of tannins.6. The damage was highly correlated within replicate clones and a model choice analysis suggested that Japanese beetle damage may be explained by four factors: concentrations of salicortin, condensed tannins, and nitrogen, as well as the specific leaf area (thick leaves were damaged less).
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| 5. |
- Baba, Yuki G., et al.
(författare)
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Host-dependent differences in prey acquisition between populations of a kleptoparasitic spider Argyrodes kumadai (Araneae: Theridiidae)
- 2007
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 32:1, s. 38-44
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Tidskriftsartikel (refereegranskat)abstract
- 1. A kleptoparasitic spider, Argyrodes kumadai, is known to use phylogenetically unrelated host species in different regions - Cyrtophora moluccensis (Araneidae) in south-west Japan and Agelena silvatica (Agelenidae) in north-east Japan. The work reported here examined whether differences in host characters affect prey acquisition of A. kumadai. 2. Field surveys showed that prey-biomass capture rate of Argyrodes was significantly higher in populations parasitising Cyrtophora than in populations parasitising Agelena. Although Argyrodes appeared to catch fewer prey within Cyrtophora webs, they were able to feed upon substantially larger prey. 3. Differences in prey-biomass capture rate were found to reflect differences in host traits rather than regional differences in potential prey availability. Individuals in populations parasitising Cyrtophora were observed to acquire prey via a number of foraging tactics that included stealing wrapped food bundles, feeding upon prey remains and, in the case of large prey items, feeding together with the host. In contrast, individuals in populations parasitising Agelena were only ever observed to feed upon small prey items ignored by its host. 4. This variability in prey acquisition between kleptoparasite populations reflected different opportunities for feeding within their respective host webs - opportunities that were primarily determined by the foraging behaviour of the host. One key trait associated with host foraging behaviour was host-web structure, namely the presence/absence of a retreat.
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| 6. |
- Bergström, Anders, et al.
(författare)
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Putting more eggs in the best basket : clutch size regulation in the comma butterfly
- 2006
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 31:3, s. 255-260
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Tidskriftsartikel (refereegranskat)abstract
- 1. Many studies have identified different factors influencing clutchsize regulation, primarily within various groups of insects. One prediction is that ovipositing females should increase clutch size with host quality. However, in many studies it is not clear whether ovipositing females are responding to host quality or quantity. 2. Females of the polyphagous comma butterfly, allowed to oviposit on two hosts differing greatly in quality: the preferred host, stinging nettle (Polygonia c-album (L.), wereUrtica dioica L.), and the low-ranked host, birch (Betula pubescens Ehrh). Ovipositing females were observed visually and clutch sizes were recorded. The experiment was repeated in three different years; in total, 938 observations of oviposition events were made. 3. In all three years, females ovipositing on (median 1.6–1.85) compared with females ovipositing on 1.0–1.3) three years were pooled. 4. Thus, on better hosts. It is suggested that the proximate mechanism is likely to be a response to the same stimuli used for female ranking of host plants in the preference hierarchy. U. dioica laid larger clutchesB. pubescens (median. The difference was significant in two out of three years and when allP. c-album females exhibit clutch-size regulation, with larger clutches
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| 7. |
- Flenner, Ida, 1976-, et al.
(författare)
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Predator-induced spine length and exocuticle thickness in Leucorrhinia dubia (Insecta : Odonata): a simple physiological trade-off?
- 2009
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Ingår i: Ecological Entomology. - Oxford : Wiley. - 0307-6946 .- 1365-2311. ; 34:6, s. 735-740
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Tidskriftsartikel (refereegranskat)abstract
- 1. Morphological defence structures evolve against predators but are costly to the individual, and are induced only when required. A well-studied example is the development of longer abdominal spines in dragonfly larvae in the presence of fish. Numerous attempts to discover trade-offs between spine size and behaviour, development time or body size have, however, produced little evidence. 2. We considered a physiological trade-off. Spines consist of cuticle and using material to build longer structures may result in less material remaining elsewhere. We therefore measured exocuticle thickness at nine locations on Leucorrhinia dubia larvae from habitats with and without fish. 3. Our results show a significant effect of the interaction between fish presence and spine length on head and fore leg exocuticle thickness. Relative thickness increased with relative length of lateral spine 9 in the absence of fish, whereas no such relationship existed with fish. Hence, synthesis and secretion of cuticle material occur as a trade-off when larvae react to fish presence. 4. We assume the mechanism to be a selective synthesis of material with different responses in different parts of the larval body. These findings offer a new angle to the fish/spine trade off debate.
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| 8. |
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| 9. |
- Janz, Niklas, et al.
(författare)
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No effect of larval experience on adult host preferences in Polygonia c-album (Lepidoptera: Nymphalidae): on the persistence of Hopkins' host selection principle
- 2009
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Ingår i: Ecological Entomology. - Oxford : Blackwell. - 0307-6946 .- 1365-2311. ; 34:1, s. 50-57
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Tidskriftsartikel (refereegranskat)abstract
- 1. The possible effect of juvenile imprinting or 'chemical legacy' on the subsequent oviposition - often called the 'Hopkins' host selection principle' - has been a controversial but recurrent theme in the literature on host-plant preference. While it appears possible in principle, experimental support for the hypothesis is equivocal. The present study points out that it is also important to consider its theoretical implications, and asks under what circumstances, if any, it should be favoured by natural selection. 2. Following this reasoning, it is predicted that host preference in the polyphagous butterfly Polygonia c-album L. (Lepidoptera, Nymphalidae) should not be influenced by larval environment. This was tested by rearing larvae on three natural host plants: the high-ranked Urtica dioica and the medium-ranked Salix cinerea and Ribes uva-crispa, and exposing the naive females to oviposition choices involving the same set of plants. 3. It was found that larval host plant had no effect on oviposition decisions of the adult female. Hence, the Hopkins' host selection principle does not seem to be applicable in this species. 4. Based on recent insights on how accuracy of environmental versus genetic information should affect the control of developmental switches, the conditions that could favour the use of juvenile cues in oviposition decisions are discussed. Although the Hopkins' host selection hypothesis cannot be completely ruled out, we argue that the circumstances required for it to be adaptive are so specific that it should not be invoked as a general hypothesis for host selection in plant-feeding insects.
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| 10. |
- Maklakov, Alexeia A., et al.
(författare)
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Inter-sexual combat and resource allocation into body parts in the spider, Stegodyphus lineatus
- 2006
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 31:6, s. 564-567
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Tidskriftsartikel (refereegranskat)abstract
- 1. Sexual conflict, which results from the divergence of genetic interests between males and females, is predicted to affect multiple behavioural, physiological, and morphological traits. 2. Sexual conflict over mating may interact with population density to produce predictable changes in resource allocation into inter-sexual armament. 3. In the spider Stegodyphus lineatus, males fight with females over re-mating. The outcome of the fight is influenced by the cephalothorax size of the contestants. The investment in armament - the cephalothorax, may be traded-off against investment in abdomen, which is a trait that affects survival and fecundity. Pay-offs may depend on population density. Both sexes are expected to adjust resource allocation into different body parts accordingly. 4. Males had increased cephalothorax/body size ratio in low densities where probability of finding another receptive female is low and females had increased cephalothorax/body size ratio in high densities where cumulative costs of multiple mating are high. 5. The results support the theoretical conjecture that population density affects resource allocation into inter-sexual armament and call for further research on the interaction between sexual selection and population density.
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| 11. |
- Maklakov, Alexei A., et al.
(författare)
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Sexual selection did not contribute to the evolution of male lifespan under curtailed age at reproduction in a seed beetle
- 2009
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 34:5, s. 638-643
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Tidskriftsartikel (refereegranskat)abstract
- 1. Sexual selection is a powerful evolutionary force that is hypothesised to play an important role in the evolution of lifespan. Here we test for the potential contribution of sexual selection to the rapid evolution of male lifespan in replicated laboratory populations of the seed beetle, Callosobruchus maculatus. 2. For 35 generations, newly hatched virgin male beetles from eight different populations were allowed to mate for 24 h and then discarded. Sexual selection was removed in half of these populations by enforcing random monogamy. 3. Classic theory predicts that because of sexual competition, males from sexually selected lines would have higher age-specific mortality rates and shorter lifespan than males from monogamous lines. 4. Alternatively, condition-dependent sexual selection may also favour genes that have positive pleiotropic effects on lifespan and ageing. 5. Males from all eight populations evolved shorter lifespans compared with the source population. However, there was no difference in lifespan between males from populations with or without sexual selection. Thus, sexual selection did not contribute to the evolution of male lifespan despite the fact that such evolution did occur in our study populations.
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| 12. |
- Åhman, Mikael, et al.
(författare)
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Flight endurance in relation to adult age in the green-veined white butterfly Pieris napi
- 2009
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 34, s. 783-787
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Tidskriftsartikel (refereegranskat)abstract
- Abstract. 1. The flight apparatus in butterflies as well as in other insects is costly to manufacture. Since most animals live in a world where resources are limited, trade-offs are expected and available resources must thus be allocated between flight and other functions such as reproduction. 2. To mitigate this trade-off, previous studies have shown that butterflies can break down flight muscles in the thorax as they age in order to use muscle nutrients for reproduction. 3. Although breakdown of flight muscles is expected to reduce flight ability, relative flight muscle ratio (thorax mass/body mass) in many butterfly species does not decrease with age. Our aim in this study was to test the relationship between flight endurance and adult age in the green-veined white butterfly Pieris napi (L.). The tests were performed in the laboratory under five different temperatures. 4. The results showed that age has a significant influence on butterfly flight endurance; older butterflies showed reduced flight endurance. Male butterflies fly for a longer time than females and flight endurance increase with temperature in both sexes.
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