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871.
Vestiges of an ancestral host plant: preference and performance in the butterfly Polygonia faunus and its sister species P. c‐album 下载免费PDF全文
SÖREN NYLIN LINA SÖDERLIND GABRIELLA GAMBERALE‐STILLE HÉLÈNE AUDUSSEAU MARIA DE LA PAZ CELORIO‐MANCERA NIKLAS JANZ FELIX A. H. SPERLING 《Ecological Entomology》2015,40(3):307-315
1. In the study of the evolution of insect–host plant interactions, important information is provided by host ranking correspondences among female preference, offspring preference, and offspring performance. Here, we contrast such patterns in two polyphagous sister species in the butterfly family Nymphalidae, the Nearctic Polygonia faunus, and the Palearctic P. c‐album. 2. These two species have similar host ranges, but according to the literature P. faunus does not use the ancestral host plant clade – the ‘urticalean rosids’. Comparisons of the species can thus test the effects of a change in insect–plant associations over a long time scale. Cage experiments confirmed that P. faunus females avoid laying eggs on Urtica dioica (the preferred host of P. c‐album), instead preferring Salix, Betula, and Ribes. 3. However, newly hatched larvae of both species readily accept and grow well on U. dioica, supporting the general theory that evolutionary changes in host range are initiated through shifts in female host preferences, whereas larvae are more conservative and also can retain the capacity to perform well on ancestral hosts over long time spans. 4. Similar rankings of host plants among female preference, offspring preference, and offspring performance were observed in P. c‐album but not in P. faunus. This is probably a result of vestiges of larval adaptations to the lost ancestral host taxon in the latter species. 5. Female and larval preferences seem to be largely free to evolve independently, and consequently larval preferences warrant more attention. 相似文献
872.
Cumberland Plain grassy woodland in western Sydney has been reduced to less than 12% of its pre‐settlement distribution; efforts to restore it on cleared and grazed sites within its former distribution have met with mixed success. Elevated soil nitrate levels, coupled with propagule and establishment limitation, have been identified as barriers to restoration in other grasslands. Our study used a factorial combination of carbon addition, fire and native seed addition to test whether these barriers operated on a former Cumberland plain woodland site dominated by exotic perennial grasses. Replicate field plots were established in November 2004; fire plots were burnt in December 2004; carbon was then added as sugar every 3 months until September 2005; and seeds of five native grasses were added in January 2005. Carbon addition significantly reduced soil nitrate, the effect appearing in October 2005. Carbon addition and fire each reduced the total abundance of exotics; when combined, they halved the abundance of the two dominant exotic grasses. Total abundance of native species responded positively to carbon and seed addition, but significant responses to carbon were not detected for individual species. Abundance of two native grasses responded positively to fire; after treatment the native proportion of total abundance rose from 26% on controls to 44–65% on carbon and/or fire plots. Exotic species richness was decreased independently by carbon addition and fire. Native species richness was increased independently by fire and seed addition. All five native grasses established sporadically, but only on carbon and/or fire plots. The three treatments each significantly and independently affected species composition, which showed the greatest change when all three were applied. The three treatments collectively increased the proportion of natives in measures of both plant abundance and species richness. The study confirmed that elevated soil nitrate, plus propagule and recruitment limitation are barriers to restoring this grassy woodland on cleared and grazed sites. 相似文献
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It has been suggested that plant physical and chemical traits vary considerably in space and time. Hence, leaf‐mining insects may adjust their oviposition in response to leaf attributes representing high quality. Moreover, herbivorous insects can modify leaf morphology by acting as stressors, increasing, for example, fluctuating asymmetry (FA) levels. Here, we investigate oviposition preference in Agnippe sp.2, a leaf‐mining moth of Erythroxylum tortuosum, in relation to differences in leaf nutritional quality (i.e. levels of water, nitrogen and tannin content), leaf area (i.e. quantity of resource hypothesis) and FA. We also verify whether temporal variation in plant nutritional quality emerges as an alternative hypothesis to explain oviposition distribution in time, and whether this leaf miner is a stress‐causing agent, increasing FA during larval development. Mined leaves and leaves with and without eggs were periodically collected from plants located in a Cerrado fragment in Brazil. In the laboratory, leaf traits were assessed (using image analysis software) and quantified (biochemical analysis) according to the aims previously determined. Oviposition probability did not change in relation to variations in nitrogen, tannins and FA of leaves. However, leaf‐miner females preferred to oviposit on leaves having large areas and low water contents. It was also verified that new leaves of E. tortuosum, which carried most leaf‐miner eggs, presented significantly lower tannins and greater levels of nitrogen and water than old leaves. The oviposition choice exhibited by leaf miners was found to be non‐random because they appear to use resource quantity and water content as cues as where to lay their eggs. The temporal variation of plant nutritional quality is likely to influence the time of leaf‐miner oviposition; and leaf FA was not increased during larval feeding, suggesting that these herbivores do not cause variations in FA levels. 相似文献
876.
L. D. EINODER B. PAGE S. D. GOLDSWORTHY S. C. DE LITTLE C. J. A. BRADSHAW 《Austral ecology》2011,36(4):461-475
Identifying the primary foraging grounds of abundant top predators is of importance in marine management to identify areas of high biological significance, and to assess the extent of competition with fisheries. We studied the search effort and habitat selection of the highly abundant short‐tailed shearwater Puffinus tenuirostris to assess the search strategies employed by this wide‐ranging seabird. During the chick‐rearing period 52 individuals were tracked performing 39 short foraging trips (1–2 days), and 13 long trips (11–32 days). First‐passage time analysis revealed that 46% of birds performing short trips employed area‐restricted searches, concentrating search effort at an average scale of 14 ± 5 km. Foraging searches were more continuous for the other 54%, who travelled faster to cover greater distances, with little evidence of area‐restricted searches. The prey returned indicated that continuous searchers consumed similar prey mass, but greater prey diversity than area‐restricted search birds. On long trips 23% of birds travelled 500–1000 km to neritic (continental shelf) habitats, showing weak evidence of preference for areas of higher chlorophyll a concentration, and foraged at a similar spatial scale to short trips. The other 76% performed rapid outbound flights of 1000–3600 km across oceanic habitats commuting to regions with higher chlorophyll a. The spatial scale of search effort in oceanic habitat varied widely with some performing broad‐scale searches (260–560 km) followed by finer‐scale nested searches (16–170 km). This study demonstrates that a range of search strategies are employed when exploiting prey across ocean basins. The trade‐offs between different search strategies are discussed to identify the value of these contrasting behaviours to wide‐ranging seabirds. 相似文献
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ZAIN BELAÚSTEGUI JORDI M. DE GIBERT JAMES H. NEBELSICK ROSA DOMÈNECH JORDI MARTINELL 《Palaeontology》2013,56(4):783-796
Abstract: Middle Miocene tests of Clypeaster from L’Arrabassada (Tarragona, north‐east Spain) show evidence of intense endoskeletozoan colonization, preserved as borings and associated carbonate secretions that allow gastrochaenid bivalves to be identified as the colonizers. Two modes of occurrence have been recognized for these bivalve dwelling cavities; ‘intrastereom clavate borings’ which are restricted to the echinoid stereom, and ‘semi‐endoskeletal dwellings’, which penetrate across the test wall and extend as carbonate crypts into the sediment fill of the internal test cavity. Their size, density and position rule out a syn‐vivo relationship with the echinoids and demonstrate that colonization was post mortem. Because of the endurance of clypeasteroid skeleton and the pronounced bell‐shaped morphology of Clypeaster, the tests of these echinoids provided the most suitable substrates for hard‐bottom colonizers on an otherwise sandy seafloor. The scenario described from Tarragona can be extended to other Neogene and Quaternary strata elsewhere; there is ample evidence for the long‐term utilization of tests of Clypeaster by gastrochaenid bivalves in shoreface palaeoenvironments. 相似文献
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W. THEUNIS S. BLÄHSER R. HUYBRECHTS A. DE LOOF 《Invertebrate reproduction & development.》2013,57(1-3):111-117
Summary Materials immunologically related to luteinising hormone (LH), follicle stimulating hormone (FSH) and the gonadotropin releasing hormone (GnRH) were localised in cerebral tissue of Locusta migratoria and Sarcophaga bullata by means of the peroxidase-antiperoxidase method. Several polyclonal and a monoclonal antisera were used. From the third larval instar a positive reaction was observed in cells located in several parts of the brain. Each antiserum reacted with a constant number of well defined cells and nerve fibers. No differences between sexes were observed. 相似文献