Climate oscillations and species interactions: large‐scale congruence but regional differences in the phylogeographic structures of an alpine plant and its monophagous insect

Aim To predict the fate of alpine interactions involving specialized species, using a monophagous beetle and its host plant as a case study. Location The Alps. Methods We investigated genetic structuring of the herbivorous beetle Oreina gloriosa and its specific host‐plant Peucedanum ostruthium. We used genome fingerprinting (in the insect and the plant) and sequence data (in the insect) to compare the distribution of the main gene pools in the two associated species and to estimate divergence time in the insect, a proxy for the temporal origin of the interaction. We quantified the similarity in spatial genetic structures by performing a Procrustes analysis, a tool from shape theory. Finally, we simulated recolonization of an empty space analogous to the deglaciated Alps just after ice retreat by two lineages from two species showing unbalanced dependence, to examine how timing of the recolonization process, as well as dispersal capacities of associated species, could explain the observed pattern. Results Contrasting with expectations based on their asymmetrical dependence, patterns in the beetle and plant were congruent at a large scale. Exceptions occurred at a regional scale in areas of admixture, matching known suture zones in Alpine plants. Simulations using a lattice‐based model suggested these empirical patterns arose during or soon after recolonization, long after the estimated origin of the interaction c. 0.5 million years ago. Main conclusions Species‐specific interactions are scarce in alpine habitats because glacial cycles have limited the opportunities for co‐evolution. Their fate, however, remains uncertain under climate change. Here we show that whereas most dispersal routes are paralleled at a large scale, regional incongruence implies that the destinies of the species might differ under changing climate. This may be a consequence of the host dependence of the beetle, which locally limits the establishment of dispersing insects.     

Effects of leaf damage on oviposition choice in an invasive paropsine beetle

In 2007, an invasive paropsine beetle, Paropsisterna nr. gloriosa Blackburn, caused severe defoliation of Eucalyptus in mixed‐species foliage plantations in south‐west Ireland. At many of the plantations, Eucalyptus parvula L.A.S. Johnson & K.D. Hill was the most heavily damaged species while Eucalyptus pulverulenta Sims was generally resistant to the beetle. However, at the most heavily damaged site beetles moved to feed on E. pulvarulenta presumably during periods when suitable foliage (new leaves) of E. parvula had been severely depleted. The present study examines factors underlying shifts in oviposition from the preferred to non‐preferred host. In choice and no‐choice experiments, P. nr. gloriosa laid more eggs directly on new E. parvula foliage compared with new E. pulverulenta foliage. However, in choice experiments where new E. parvula foliage was unavailable (but old foliage available), more eggs were laid on new E. pulverulenta foliage. The potential for prior feeding damage to stimulate or deter oviposition on either host was also examined. Prior damage to new and old E. parvula leaves increased egg‐laying directly on the damaged foliage; however, prior damage to E. pulverulenta may have inhibited oviposition. The results suggest that in mixed‐species plantations, facilitation of oviposition on preferred hosts through prior feeding damage helps maintain the relative resistance of E. pulverulenta against P. nr. gloriosa, even under high beetle densities. However, the vulnerability of E. pulverulenta will increase where suitable age‐classes of preferred‐host foliage are severely depleted or unavailable.     

凤尾丝兰子房离体培养的器官发生及植株再生

用凤尾丝兰(Yucca gloriosa L.)离体子房为外植体接种材料,在附加KT、2,4-D及LH的MS培养基上诱导子房膨胀及愈伤组织发生;在附加6-BA、NAA及LH的MS培养基上诱导大量丛生芽;转至MS附加IBA的培养基上则能诱导根系形成;在间歇性高温灭菌及药物拌土的基质上,移植成活率达72%以上,得到了批量成苗。经镜检,试管苗与原株根蘖苗染色体数目一致。并对培养中各分化阶段进行了过氧化物酶活性测定,发现过氧化物酶活性随分化进展逐渐提高,呈正相关。     

Leaf anatomy is not correlated to CAM function in a C3+CAM hybrid species,Yucca gloriosa

Background and AimsCrassulacean acid metabolism (CAM) is often considered to be a complex trait, requiring orchestration of leaf anatomy and physiology for optimal performance. However, the observation of trait correlations is based largely on comparisons between C₃ and strong CAM species, resulting in a lack of understanding as to how such traits evolve and the level of intraspecific variability for CAM and associated traits.MethodsTo understand intraspecific variation for traits underlying CAM and how these traits might assemble over evolutionary time, we conducted detailed time course physiological screens and measured aspects of leaf anatomy in 24 genotypes of a C₃+CAM hybrid species, Yucca gloriosa (Asparagaceae). Comparisons were made to Y. gloriosa’s progenitor species, Y. filamentosa (C₃) and Y. aloifolia (CAM).Key ResultsBased on gas exchange and measurement of leaf acids, Y. gloriosa appears to use both C₃ and CAM, and varies across genotypes in the degree to which CAM can be upregulated under drought stress. While correlations between leaf anatomy and physiology exist when testing across all three Yucca species, such correlations break down at the species level in Y. gloriosa.ConclusionsThe variation in CAM upregulation in Y. gloriosa is a result of its relatively recent hybrid origin. The lack of trait correlations between anatomy and physiology within Y. gloriosa indicate that the evolution of CAM, at least initially, can proceed through a wide combination of anatomical traits, and more favourable combinations are eventually selected for in strong CAM plants.     

Outbreak of an invasive paropsine beetle in south‐west Ireland: preference,performance and damage to Eucalyptus

An exotic, paropsine beetle –Paropsisterna nr. gloriosa Blackburn – occurred at high densities in south‐west Ireland in 2007. In bioassays, adults and larvae fed on foliage from a variety of eucalypt species. Eggs and neonates occurred only in association with new foliage. Despite their ability to consume old foliage, adult beetles had a high preference for new leaves with low specific leaf weights (softer leaves). In choice tests, adults that depleted new foliage of their preferred host, moved to new foliage of a second host but not older foliage of the preferred host. A 2008 survey of southern Ireland indicated that P. nr. gloriosa was restricted to County Kerry, largely associated with foliage plantations in that county. The distribution of damage suggests that the initial spread of the beetle was facilitated by foliage‐trade activities. Eucalyptus parvula L.A.S. Johnson & K.D. Hill was the most heavily damaged species at many plantations. Eucalyptus pulverulenta Sims and Eucalyptus cordata Labill. were highly resistant to the beetle as indicated by low levels of damage in the field and reduced fitness of larvae in feeding trials. Nevertheless, at the plantation with the highest overall levels of damage, adult beetles moved to feed on E. pulverulenta. A progressive dispersal from plantations also caused slight damage to neighbouring ornamental eucalypts. Clear preferences by P. nr. gloriosa for new foliage, irrespective of eucalypt species, suggests that pollarding – the removal of top branches to produce dense juvenile foliage – accelerated population build‐up during 2007.     

Discontinuous ventilation and energetics of locomotion in the desert-dwelling female mutillid wasp, Dasymutilla gloriosa

Abstract. Data on the discontinuous ventilation cycle and cost of pedestrian locomotion in female Dasymutilla gloriosa (Sauss.), a desert-dwelling mutillid, are described and compared with equivalent data from other Hymenoptera. The discontinuous ventilation cycle was intermediate between that found in xeric and mesic hymenopterans, with the open phase being about 20% of the cycle. No noticeable flutter phase was observed. Thus D. gloriosa does not attempt to reduce respiratory water loss to the same extent as found in other desert dwelling Hymenoptera. The minimum cost of transport was significantly higher than that obtained for several ant species, indicating that ants are probably more efficient runners than any other Hymenoptera.