Is top‐down control by predators driving insect abundance and herbivory rates in fragmented forests?

The effects of forest fragmentation on ecological interactions and particularly on food webs have scarcely been analysed. There is usually less herbivory in forest fragments than in continuous forests. Here we hypothesize that forest fragmentation enhances top‐down control of herbivory through an increase in insectivorous birds and a decrease in herbivorous insects, with a consequent decrease in plant reproductive success in small forest fragments. In the Maulino forest in central Chile, we experimentally excluded birds from Aristotelia chilensis (Elaeocarpaceae) trees in both forest fragments and continuous forest, and analysed herbivore insect abundance, herbivory and plant reproductive success during two consecutive growing seasons. We expected that insect abundance and herbivory would increase, and reproductive success would decrease in A. chilensis from which birds have been excluded, particularly in forest fragments where bird abundance and predation pressure on insects is higher. The abundance of herbivorous insects was lower in the forest fragments than in the continuous forest only in the first season, and herbivory was lower in forest fragments than in the continuous forest throughout the study. Moreover, during the second growing season herbivory was greater in the excluded trees than in the control trees, and as expected, there was a greater difference in the fragments than in the continuous forest, but this was not statistically significant. Exclusion of birds did not affect the reproductive success of A. chilensis. Our results, after 2 years of study, demonstrate that birds affect the levels of herbivory on A. chilensis in the Maulino forest, but do not support our hypothesis of enhanced top‐down control in fragmented forests, as the strength of the effect of excluding birds did not vary with fragmentation.     

Phytochrome B increases drought tolerance by enhancing ABA sensitivity in Arabidopsis thaliana

Phytochrome B (phyB) can adjust morphological and physiological responses according to changes in the red : far‐red (R:FR) ratio. phyB‐driven acclimation of plants to open environments (high R:FR ratio) increases carbon gain at the expense of increased water loss. This behaviour alleviates stressful conditions generated by an excess of light, but increases the chances of desiccation. Here we evaluated how phyB modulates this drought‐tolerance response by comparing wild‐type Arabidopsis thaliana adult plants to the null phyB in response to water shortage. phyB wilted before the wild type, and this was due to phyB maintaining open stomata under a reduction in soil water availability. Although phyB presented enhanced ABA levels under well‐watered conditions, this mutant was less sensitive than the wild type in diminishing stomatal conductance in response to exogenous ABA application. Reduced sensitivity to ABA in phyB correlated with a lower expression of ABCG22, which encodes a putative ABA influx transporter, and PYL5, which encodes a soluble ABA receptor. Furthermore, the expression of RAB18 and RD29A, both typical ABA‐induced genes, was lower in phyB than the wild type after ABA treatment. We propose that phyB contributes to the acclimation of plants to open environments by enhancing ABA sensitivity when soil water becomes limiting.     

Isolation and characterization of eight microsatellite loci from Phaedranassa tunguraguae (Amaryllidaceae)

Phaedranassa tunguraguae is an endangered species endemic to Ecuador. Eight highly polymorphic microsatellite loci were isolated from an enriched genomic library for this species. Levels of polymorphism were evaluated using a total of 31 individuals from a single natural population. An average of 14.1 alleles per locus was detected, and observed heterozygosity ranged from 0.387 to 0.903. All but one locus depart significantly from Hardy–Weinberg equilibrium. These loci are the first microsatellite primers isolated for Amaryllidaceae and will be utilized to investigate patterns of genetic variation of P. tunguraguae, which will contribute data relevant to the conservation of the species.     

The Influence of Ecological Factors on Detecting Drumming Ruffed Grouse

Abstract: We surveyed drumming ruffed grouse (Bonasa umbellus) to estimate the probability of detecting an individual, and we used Bayesian model selection to assess the influence of factors that may affect detection probabilities of drumming grouse. We found the average probability of detecting a drumming ruffed grouse during a daily survey was 0.33. The probability of detecting a grouse was most strongly influenced by the temperature change during a survey (_{temp change} = 0.23, 95% probability interval [PI] = 0.13 ≤ ≤ 0.33) and its interaction with temperature at the start of the survey (_interaction = 0.01, 95% PI = 1.42 × 10⁻³ ≤ ≤ 0.03). Although the best model also included a main effect of temperature at the start of surveys, this variable did not strongly correlate with detection probabilities (_{start temp} = −0.03, 95% PI = −0.06 ≤ ≤ 9.80 × 10⁻⁵). Model assessment using data collected at other sites indicated that this best model performed adequately (i.e., positive correlation between observed and predicted values) but did not explain much of the variation in detection rates. Our results are useful for understanding the historical drumming index used to assess ruffed grouse populations and for designing auditory surveys for this important game bird.     

A metabolomic study in oats (Avena sativa) highlights a drought tolerance mechanism based upon salicylate signalling pathways and the modulation of carbon,antioxidant and photo‐oxidative metabolism

Although a wealth of information is available on the induction of one or several drought‐related responses in different species, little is known of how their timing, modulation and crucially integration influence drought tolerance. Based upon metabolomic changes in oat (Avena sativa L.), we have defined key processes involved in drought tolerance. During a time course of increasing water deficit, metabolites from leaf samples were profiled using direct infusion–electrospray mass spectroscopy (DI‐ESI‐MS) and high‐performance liquid chromatography (HPLC) ESI‐MS/MS and analysed using principal component analysis (PCA) and discriminant function analysis (DFA). The involvement of metabolite pathways was confirmed through targeted assays of key metabolites and physiological experiments. We demonstrate an early accumulation of salicylic acid (SA) influencing stomatal opening, photorespiration and antioxidant defences before any change in the relative water content. These changes are likely to maintain plant water status, with any photoinhibitory effect being counteracted by an efficient antioxidant capacity, thereby representing an integrated mechanism of drought tolerance in oats. We also discuss these changes in relation to those engaged at later points, consequence of the different water status in susceptible and resistant genotypes.     

Morphological and allozyme variation of Eidolon helvum (Mammalia: Megachiroptera) in the islands of the Gulf of Guinea

Morphological and genetic variation is evaluated among populations of the bat, Eidolon helvum , in the islands of the Gulf of Guinea (Central Africa). The populations from the islands of Bioko, Principe, and Sao Tome do not show significant phenetic differentiation, although a trend towards a reduction of size is found in the latter two islands. The low genetic distances between populations, as well as their values of Wright's fixation indexes, suggest that gene flow has hampered differentiation on these islands. In contrast, the population from Annobon, the smallest and farthermost island, shows remarkable morphological and genetic differentiation. On the mainland, E. helvum displays unique migratory and dispersal behaviours, but migratory behaviour was not found in any of the island populations. The combination of selective forces in harsher oceanic environments and restricted gene flow among populations appears to have favoured the high degree of morphological differentiation of E. helvum on Annobon. Due to the extended length of the dry season in Annobon, an earlier achievement of sexual maturity–and consequently smaller size—may be advantageous in the absence of migration. The differentiation is more marked among females, which also suggests that selection may be linked to the reproductive pattern. The population of the island of Annobon is herein described as a new subspecies, Eidolon helvum annobonensis subsp. nov.     

Chemotaxonomic study of seed glucosinolate composition in Coincya Rouy (Brassicaceae)

A total of 68 populations belonging to the genus Coincya Rouy (Brassicaceae) from the Iberian Peninsula was examined for seed glucosinolate composition. The presence of progoitrin, epiprogoitrin, glucosinalbin and gluconapin was recorded plus a fifth glucosinolate that could not be identified. A geographical clinal variation between progoitrin and epiprogoitrin was observed in the more widespread taxa, C. monensis subsp. orophila (Franco) Aedo, Leadiay & Murioz Garm. and C. moncnsis subsp. cheiranthos var. recurvata (All.) Leadiay. The fewest types of glucosinatc were observed in taxa with morphological characters considered more primitive, viz. subsp. hispida and var. recurvata. On the other hand, more complex and diverse composition was observed in the taxon with more advanced characters, viz. C. rupestris subsp. rupestris Porta & Rigo.     

On the nomenclature and types of Chamaecytisus proliferus (L.f.) Link (Fabaceae: Genisteae), a fodder shrub from the Canary Islands

The name Cytisus proliferus L.f. is here considered perfectly acceptable and should not be replaced by Cytisus prolifer L.f. One specimen from The Natural History Museum, London is confirmed as the lectotype of Cytisus proliferus L.f. Two specimens from the collection of the Swiss botanist Hermann Christ from the Main Herbarium of the Zurich Botanical Garden were selected as lectotypes for Cytisus proliferus L.f. var. canariae H. Christ and Cytisus proliferus L.f. var. palmensis H. Christ. The name Cytisus proliferus Kit. is typified and a specimen from Paul Kitaibel's collection at the Botanical Department of the Hungarian Natural History Museum is assigned as its lectotype.