Variation in the reproductive success of a narrow endemic plant: Effects of geographical distribution, abiotic conditions and pollinator community composition

Fernandez J.D., Lorite J., Bosch J., Gomez J.M. (2015) Variation in the reproductive success of a narrow endemic plant: Effects of geographical distribution, abiotic conditions and pollinator community composition. Basic and Applied Ecology. 16: 375-385.
Link
Doi: 10.1016/j.baae.2015.02.006

Abstract:

Geographic variation in reproductive output determines plant distribution. In this study, we investigate the geographic structure and the factors affecting reproductive success throughout the life cycle of the near-threatened crucifer Erysimum popovii across its entire distribution range. We worked in 21 populations, in which we measured fruit set, seed set, seed weight, seed germination in the laboratory, germination time, seedling emergence in the field, seedling survival and fecundity. We also sampled the pollinator assemblages visiting E. popovii at each site, as well as some population characteristics (population size and density, flower density of E. popovii and other co-occurring species, and rainfall). Germination success in the laboratory was very high (range: 0.56-0.98), but seedling emergence in the field was low (0.005-0.32). Beefly visitation rate was positively related to seedling emergence, whereas visitation rate by ants, beetles and other minor pollinator groups was negatively related to fruit set and positively related to germination time. Populations in sites with high density of co-occurring flowers produced fewer fruits. Most variables related to reproductive output varied widely across populations, but this variation did not show a clear regional structure. The low seedling survival may constitute a bottleneck for the recruitment of this species. Overall, less than 0.2% of the ovules produced developed into reproductive individuals. Our results suggest a metapopulation structure for E. popovii. © 2015 Gesellschaft für Ökologie.

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Social evolution. Genomic signatures of evolutionary transitions from solitary to group living

Kapheim K.M., Pan H., Li C., Salzberg S.L., Puiu D., Magoc T., Robertson H.M., Hudson M.E., Venkat A., Fischman B.J., Hernandez A., Yandell M., Ence D., Holt C., Yocum G.D., Kemp W.P., Bosch J., Waterhouse R.M., Zdobnov E.M., Stolle E., Kraus F.B., Helbing S., Moritz R.F., Glastad K.M., Hunt B.G., Goodisman M.A., Hauser F., Grimmelikhuijzen C.J., Pinheiro D.G., Nunes F.M., Soares M.P., Tanaka ED., Simoes Z.L., Hartfelder K., Evans J.D., Barribeau S.M., Johnson R.M., Massey J.H., Southey B.R., Hasselmann M., Hamacher D., Biewer M., Kent C.F., Zayed A., Blatti C., Sinha S., Johnston J.S., Hanrahan S.J., Kocher S.D., Wang J., Robinson G.E., Zhang G. (2015) Social evolution. Genomic signatures of evolutionary transitions from solitary to group living. Science (New York, N.Y.). 348: 1139-1143.
Link
Doi: 10.1126/science.aaa4788

Abstract:

The evolution of eusociality is one of the major transitions in evolution, but the underlying genomic changes are unknown. We compared the genomes of 10 bee species that vary in social complexity, representing multiple independent transitions in social evolution, and report three major findings. First, many important genes show evidence of neutral evolution as a consequence of relaxed selection with increasing social complexity. Second, there is no single road map to eusociality; independent evolutionary transitions in sociality have independent genetic underpinnings. Third, though clearly independent in detail, these transitions do have similar general features, including an increase in constrained protein evolution accompanied by increases in the potential for gene regulation and decreases in diversity and abundance of transposable elements. Eusociality may arise through different mechanisms each time, but would likely always involve an increase in the complexity of gene networks. Copyright © 2015, American Association for the Advancement of Science.

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Local and landscape effects in a host-parasitoid interaction network along a forest-cropland gradient

Osorio S., Arnan X., Bassols E., Vicens N., Bosch J. (2015) Local and landscape effects in a host-parasitoid interaction network along a forest-cropland gradient. Ecological Applications. 25: 1869-1879.
Link
Doi: 10.1890/14-2476.1

Abstract:

Land-use driven habitat modification is a major driver of biodiversity loss and impoverishment of interaction diversity. This may affect ecosystem services such as pollination and biological control. Our objective is to analyze the effects of local (nesting environment: farms vs. tree stands) and landscape (forest-cropland gradient) factors on the structure and composition of a cavity-nesting bee-wasp (CNBW) community, their nests associates (henceforth parasitoids), and their interactions. We set up 24 nest-trapping stations in a fragmented, extensively farmed area of ∼100 km2. We obtained 2035 nests containing 7572 brood cells representing 17 bee and 18 wasp species, attacked by 20 parasitoid species. Community structure and composition, as well as network structure, were much more dependent on local than on landscape factors. Host abundance and richness were higher in farms. In addition, host abundance was positively correlated to cropland cover. We also found highly significant differences between nesting environments in host community composition. Structure and composition of the parasitoid community were conditioned by the structure and composition of the host community. Network structure was affected by nesting environment but not by landscape factors. Interactions tended to be more diverse in farms. This result was mostly explained by differences in network size (greater in farms). However, generality was significantly higher in farms even after controlling for network size, indicating that differences in species' interaction patterns associated to differences in community composition between the two nesting environments are also affecting network structure. In conclusion, open habitats associated with extensively farmed exploitations favor local CNBW diversity (especially bees) and result in more complex host-parasitoid interaction networks in comparison to forested areas. The conservation value of this kind of open habitat is important in view of the progressive abandonment of extensively cultivated farmland taking place in Europe at the expense of agricultural intensification and reforestation. © 2015 by the Ecological Society of America.

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Pre-wintering conditions and post-winter performance in a solitary bee: Does diapause impose an energetic cost on reproductive success?

Sgolastra F., Arnan X., Pitts-Singer T.L., Maini S., Kemp W.P., Bosch J. (2015) Pre-wintering conditions and post-winter performance in a solitary bee: Does diapause impose an energetic cost on reproductive success?. Ecological Entomology. : 0-0.
Link
Doi: 10.1111/een.12292

Abstract:

1. Diapause is a dynamic process of low metabolic activity that allows insects to survive periods of harsh conditions. Notwithstanding the lowered metabolism, and because diapausing insects have no access to food, diapause has an energetic cost that may affect post-diapause performance. 2. Previous studies on the solitary bee Osmia lignaria have shown that prolonged pre-wintering periods (the time during which individuals already in diapause remain at warm temperatures) are associated with elevated lipid consumption, fat body depletion, and body weight loss. The present study investigated whether prolonged pre-wintering also affects reproduction, i.e. whether the costs associated with diapause could have an effect on post-diapause performance in this species. 3. Females were exposed to a range of pre-wintering conditions, and ovary development and individual post-wintering performance were monitored throughout their adult life span. 4. No evidence of an effect of pre-wintering duration on post-diapause reproductive success was found. Expected differences in the timing of establishment were not observed because ovary maturation was, surprisingly, not arrested during pre-wintering. Prolonged pre-wintering duration did not result in decreased life span, probably because emerging females could rapidly replenish their metabolic reserves through feeding. However, there was a very strong effect of the duration of the pre-emergence period on the likelihood of nest establishment. 5. Longevity, the main factor determining fecundity in Osmia, is subjected to high levels of intrinsic variability, even among females of similar size exposed to identical conditions during development and nesting. © 2015 The Royal Entomological Society.

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Collateral effects of beekeeping: Impacts on pollen-nectar resources and wild bee communities

Torné-Noguera A., Rodrigo A., Osorio S., Bosch J. (2015) Collateral effects of beekeeping: Impacts on pollen-nectar resources and wild bee communities. Basic and Applied Ecology. : 0-0.
Link
Doi: 10.1016/j.baae.2015.11.004

Abstract:

Due to the contribution of honey bees (Apis mellifera) to wild flower and crop pollination, beekeeping has traditionally been considered a sustainable practice. However, high honey bee densities may have an impact on local pollen and nectar availability, which in turn may negatively affect other pollinators. This is exacerbated by the ability of honey bees to recruit foragers to highly rewarding flower patches. We measured floral resource consumption in rosemary (Rosmarinus officinalis) and thyme (Thymus vulgaris) in 21 plots located at different distances from apiaries in the scrubland of Garraf Natural Park (Barcelona), and related these measures to visitation rates of honey bees, bumblebees (Bombus terrestris) and other pollinators. In the same plots, we measured flower density, and used pan traps to characterize the wild bee community. Flower resource consumption was largely explained by honey bee visitation and marginally by bumblebee visitation. After accounting for flower density, plots close to apiaries had lower wild bee biomass. This was due to a lower abundance of large bee species, those more likely to be affected by honey bee competition. We conclude that honey bees are the main contributors to pollen/nectar consumption of the two main flowering plants in the scrubland, and that at the densities currently occurring in the park (3.5hives/km2) the wild bee community is being affected. Our study supports the hypothesis that high honey bee densities may have an impact on other pollinators via competition for flower resources. Wegen des Beitrages der Honigbiene (Apis mellifera) bei der Bestäubung von Wildblumen und Nutzpflanzen wurde die Bienenhaltung traditionell als eine nachhaltige Aktivität angesehen. Indessen können hohe Honigbienendichten Auswirkungen auf die lokale Verfügbarkeit von Nektar und Pollen haben, was wiederum andere Bestäuber negativ beeinflussen könnte. Dies wird verstärkt durch die Fähigkeit der Honigbiene, Sammlerinnen zu lohnenden Sammelstellen zu dirigieren. Im Buschland des Garraf-Naturparks bei Barcelona maßen wir den Verbrauch von Blütenressourcen an Rosmarin (Rosmarinus officinalis) und Thymian (Thymus vulgaris) an 21 Standorten, die unterschiedlich weit von Bienenständen entfernt lagen, und setzten diese Werte in Bezug zu den Besuchsraten von Honigbienen, Hummeln (Bombus terrestris) und sonstigen Bestäubern. An den gleichen Standorten bestimmten wir die Blütendichte und setzten Farbschalen ein, um die Wildbienengemeinschaft zu erfassen. Die Nutzung der Blüt enressou wurde weitgehend durch die Besuchsraten der Honigbiene erklärt und in geringfügigem Maße durch Hummelbesuch. Nach Berücksichtigung der Blütendichte wiesen Standorte in der Nähe von Bienenständen eine geringere Wildbienen-Biomasse auf. Dies war auf eine geringere Abundanz der großen Wildbienenarten zurückzuführen, also der Arten, die wahrscheinlich durch die Konkurrenz der Honigbiene beeinträchtigt werden. Wir schließen, dass Honigbienen den größten Beitrag zum Pollen- bzw. Nektarverbrauch bei den beiden wichtigsten Blütenpflanzen des Gebietes leisten und dass die Wildbienengemeinschaft bei den gegenwärtigen Honigbienendichten im Park (3.5 Völker/km2) beeinflusst wird. Unsere Untersuchung unterstützt die Hypothese, dass hohe Honigbienendichten durch Konkurrenz um Blütenressourcen einen Einfluss auf andere Bestäuber haben könnten. © 2015 Gesellschaft für Ökologie.

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Key molecular processes of the diapause to post-diapause quiescence transition in the alfalfa leafcutting bee Megachile rotundata identified by comparative transcriptome analysis

Yocum G.D., Rinehart J.P., Horvath D.P., Kemp W.P., Bosch J., Alroobi R., Salem S. (2015) Key molecular processes of the diapause to post-diapause quiescence transition in the alfalfa leafcutting bee Megachile rotundata identified by comparative transcriptome analysis. Physiological Entomology. : 0-0.
Link
Doi: 10.1111/phen.12093

Abstract:

Insect diapause (dormancy) synchronizes an insect's life cycle to seasonal changes in the abiotic and biotic resources required for development and reproduction. Transcription analysis of diapause to post-diapause quiescent transition in the alfalfa leafcutting bee Megachile rotundata Fabricius identifies 643 post-diapause up-regulated gene transcripts and 242 post-diapause down-regulated transcripts. The log2 fold change in gene expression levels ranges from -5 to 7. Transcripts from several pivotal diapause-related processes, including chromatin remodelling, cellular signalling pathways, microRNA processing, anaerobic glycolysis, cell cycle arrest and neuroendocrine control, are identified as being differentially expressed during the diapause to post-diapause transition. In conjunction with studies from other insect species, the data indicate that there are several common mechanisms of diapause control and maintenance. © 2015 The Royal Entomological Society.

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