Arias-Leclaire H., Bonal R., GarcÍa-LÓpez D., Espelta J.M. (2018) Role of seed size, phenology, oogenesis and host distribution in the specificity and genetic structure of seed weevils (Curculio spp.) in mixed forests. Integrative Zoology. 13: 267-279.LinkDoi: 10.1111/1749-4877.12293
Synchrony between seed growth and oogenesis is suggested to largely shape trophic breadth of seed-feeding insects and ultimately to contribute to their co-existence by means of resource partitioning or in the time when infestation occurs. Here we investigated: (i) the role of seed phenology and sexual maturation of females in the host specificity of seed-feeding weevils (Curculio spp.) predating in hazel and oak mixed forests; and (ii) the consequences that trophic breadth and host distribution have in the genetic structure of the weevil populations. DNA analyses were used to establish unequivocally host specificity and to determine the population genetic structure. We identified 4 species with different specificity, namely Curculio nucum females matured earlier and infested a unique host (hazelnuts, Corylus avellana) while 3 species (Curculio venosus, Curculio glandium and Curculio elephas) predated upon the acorns of the 2 oaks (Quercus ilex and Quercus pubescens). The high specificity of C. nucum coupled with a more discontinuous distribution of hazel trees resulted in a significant genetic structure among sites. In addition, the presence of an excess of local rare haplotypes indicated that C. nucum populations went through genetic expansion after recent bottlenecks. Conversely, these effects were not observed in the more generalist Curculio glandium predating upon oaks. Ultimately, co-existence of weevil species in this multi-host-parasite system is influenced by both resource and time partitioning. To what extent the restriction in gene flow among C. nucum populations may have negative consequences for their persistence in a time of increasing disturbances (e.g. drought in Mediterranean areas) deserves further research. © 2017 The Authors. Integrative Zoology published by International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd
Bogdziewicz M., Bonal R., Espelta J.M., Kalemba E.M., Steele M.A., Zwolak R. (2018) Invasive oaks escape pre-dispersal insect seed predation and trap enemies in their seeds. Integrative Zoology. 13: 228-237.LinkDoi: 10.1111/1749-4877.12285
Species introduced to habitats outside their native range often escape control by their natural enemies. Besides competing with native species, an alien species might also affect the native herbivores by introducing a new source of different quality food. Here, we describe the case of northern red oak (Quercus rubra) invasion in Europe. We collected data on insect (moth Cydia spp. and weevil Curculio spp.) seed predation of northern red oak in its native (USA, North America) and invasive (Poland, Europe) range, as well as for sessile oaks (Quercus petrea) in Europe. We also evaluated the quality of acorns as hosts for weevil larvae by collecting infested acorns and measuring weevil developmental success, and quantifying acorn traits such as seed mass, tannins, lipids and protein concentration. We used DNA barcoding to identify insects to the species level. The predation by moths was similar and very low in both species and in both ranges. However, red oaks escape pre-dispersal seed predation by weevils in Europe. Weevil infestation rates of northern red oak acorns in their invasive range were 10 times lower than that of sessile oaks, and also 10 times lower than that of red oaks in North America. Furthermore, even when weevils oviposited into northern red oaks, the larvae failed to develop, suggesting that the exotic host created a trap for the insect. This phenomenon might gradually decrease the local abundance of the seed predator, and further aid the invasion. © 2017 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd
Bogdziewicz M., Espelta J.M., Muñoz A., Aparicio J.M., Bonal R. (2018) Effectiveness of predator satiation in masting oaks is negatively affected by conspecific density. Oecologia. 186: 983-993.LinkDoi: 10.1007/s00442-018-4069-7
Variation in seed availability shapes plant communities, and is strongly affected by seed predation. In some plant species, temporal variation in seed production is especially high and synchronized over large areas, which is called ‘mast seeding’. One selective advantage of this phenomenon is predator satiation which posits that masting helps plants escape seed predation through starvation of predators in lean years, and satiation in mast years. However, even though seed predation can be predicted to have a strong spatial component and depend on plant densities, whether the effectiveness of predator satiation in masting plants changes according to the Janzen-Connell effect has been barely investigated. We studied, over an 8-year period, the seed production, the spatiotemporal patters of weevil seed predation, and the abundance of adult weevils in a holm oak (Quercus ilex) population that consists of trees interspersed at patches covering a continuum of conspecific density. Isolated oaks effectively satiate predators, but this is trumped by increasing conspecific plant density. Lack of predator satiation in trees growing in dense patches was caused by re-distribution of insects among plants that likely attenuated them against food shortage in lean years, and changed the type of weevil functional response from type II in isolated trees to type III in trees growing in dense patches. This study provides the first empirical evaluation of the notion that masting and predator satiation should be more important in populations that start to dominate their communities, and is consistent with the observation that masting is less frequent and less intense in diverse forests. © 2018, The Author(s).
Molina E., Espelta J.M., Pino J., Bagaria G., Armenteras D. (2018) Influence of clay licks on the diversity and structure of an Amazonian forest. Biotropica. 50: 740-749.LinkDoi: 10.1111/btp.12568
The spatial heterogeneity of resource availability is a major driver of biodiversity patterns. Some environmental conditions and resources are characterized by large-scale patterns of variation within the landscape. Clumped local discontinuities or discrete elements also increase spatial heterogeneity, promoting local ‘biodiversity hot spots’ by modifying habitat characteristics and promoting plant–animal interactions. Clay licks are faunal attractors owing to their role in the nutritional ecology of the user species; nevertheless, the effect of their presence on the surrounding vegetation has been poorly quantified. Here, we use data from 100 × 10 m transects and evaluate the effects of the presence of clay licks on forest diversity and structure at local and landscape scales. In clay lick areas, there was a higher abundance of certain species, which helps to homogenize species composition between localities counteracting the natural distance-decay of compositional similarity between transects without clay lick influence (controls). Compared to control sites, clay lick′s forests had higher palm densities, shorter but more variable individuals in the canopy and understory, a thinner canopy layer, and denser herbaceous and ground level covers. These differences were found along the whole length of transects in both sampled areas types. These results reveal that the presence of discrete elements (i.e., clay licks) may help to explain the compositional and structural heterogeneity of Amazonian forests influencing ecological processes such as seed dispersal and trampling. These considerations may be relevant for other biomes where clay licks are present and give weight to their inclusion in conservation initiatives in tropical forests. © 2018 The Association for Tropical Biology and Conservation
Molowny-Horas R., Borrego A., Riera P., Espelta J.M. (2018) Severe wildfire in a mediterranean forest. Equivalency Methods for Environmental Liability: Assessing Damage and Compensation Under the European Environmental Liability Directive. : 203-234.LinkDoi: 10.1007/978-90-481-9812-2_11
This case study illustrates the equivalency analysis for estimating ex post environmental damage and appropriate compensatory remediation following a severe wildfire caused by a power line in a forest protected under the European Union Habitats Directive (HD). The study addresses long-term environmental damage (e.g., over several decades) by a large-scale disturbance in a terrestrial ecosystem, and includes an analysis of uncertainty associated with the potential occurrence of natural future fire events in the area. Accounting for the probability of natural future forest fires directly affects both baseline and compensatory remediation options by reducing the habitat area compared to an assumption of no future forest fires. Only natural forest fires, i.e., 10% of all forest fires, have been included in the calculations of both the baseline and the compensatory remediation, since the operator may not be made liable for accidental or provoked forest fires. The impact of this hypothesis is tested by means of a sensitivity analysis. The case study illustrates: • Considerations in selecting a metric from various potential ones (hectares, trees, biomass, habitat quality) for terrestrial habitats included in the HD; • Application of a value equivalency approach (specifically, value-to-value); • Analysis of key variables (e.g., differences in metrics, single/multiple metrics, on-site/off-site implementation); and • Sensitivity of the results to changes in four key model parameters (i.e. area of future forest fires, tree mortality, percentage of natural forest fires and tree minimum diameter at breast height). © Springer Science+Business Media B.V. 2018.
Ruiz-Carbayo, H., Bonal, R., Pino, J., Espelta, J.M. (2018) Zero-sum landscape effects on acorn predation associated with shifts in granivore insect community in new holm oak (Quercus ilex) forests. Diversity and Distributions. : 0-0.LinkDoi: 10.1111/ddi.12701
Urgoiti J., MuÑoz A., Espelta J.M., Bonal R. (2018) Distribution and space use of seed-dispersing rodents in central Pyrenees: implications for genetic diversity, conservation and plant recruitment. Integrative Zoology. 13: 307-318.LinkDoi: 10.1111/1749-4877.12301
The function and conservation of many forest ecosystems depend on the distribution and diversity of the community of rodents that consume and disperse seeds. The habitat preferences and interactions are especially relevant in alpine systems where such granivorous rodents reach the southernmost limit of their distribution and are especially sensitive to global warming. We analyzed the community of granivorous rodents in the Pyrenees, one of the southernmost mountain ranges of Europe. Rodent species were identified by DNA with particular attention to the Apodemus species, which are prominent seed-dispersing rodents in Europe. We confirmed for the first time the presence of the yellow-necked mouse, Apodemus flavicollis, in central Pyrenees, a typical Eurosiberian species that reaches its southernmost distribution limit in this area. We also found the wood mouse, Apodemus sylvaticus, a related species more tolerant to Mediterranean environments. Both rodents were spatially segregated by altitude. A. sylvaticus was rare at high altitudes, which might cause the genetic differentiation between populations of the different valleys reported here. We also found other seed consumers like dormice, Elyomis quercinus, and voles, Myodes glareolus, with marked habitat preferences. We suggest that population isolation among valleys may increase the genetic diversity of rodents, like A. sylvaticus. We also highlight the potential threat that global warming may represent for species linked to high-altitude refuges at the southern edge of its distribution, like Apodemus flavicollis. Finally, we discuss how this threat may have a dimension in the conservation of alpine forests dispersed by these rodent populations. © 2018 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd
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