Publicaciones

Increasing aridity reduces soil microbial diversity and abundance in global drylands.

Maestre, F., Delgado-Baquerizo, M., Jeffries, T., Eldridge, D., Ochoa, V., & Gozalo, B. Quero, J.L., García-Gómez, M., Gallardo, A., Ulrich, W., Bowker, M.A., Arredondo, T., Barraza-Zepeda, C., Bran, D., Florentino, A., Gaitán, J., Gutiérrez, J.R. et al.

Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands.

Año: 2015

Palabras claves: Bacteria, fungi, climate change, arid, semiarid .

Positive interactions by cushion plants in high mountains: fact or artifact?.

Molina-Montenegro, M., Oses, R., Acuña-Rodríguez, I., Fardella, C., Badano, E., & Torres-Morales, P. et al.

Positive interactions are defined as non-trophic interactions where at least one of the interacting species is benefited in terms of fitness and the other remains unaffected. Nevertheless, the bidirectional feedbacks between species may be positive, neutral or negative. Thus, if facilitated species induce negative effects on their ‘nurses’, the assumed definition of positive interactions could be reconsidered.

Año: 2015

Palabras claves: Cushion plants, facilitation, nurse effect, positive interactions, stress gradient hypothesis.

Ancient and modern introduction of Broussonetia papyrifera ([L.] Vent.; Moraceae) into the Pacific: genetic, geographical and historical evidence.

González-Lorca, J., Rivera-Hutinel, A., Moncada, X., Lobos, S., Seelenfreund, D., & Seelenfreund, A.

Broussonetia papyrifera (L.) Vent. (Moraceae), or paper mulberry, is a species of cultural importance in South East Asia, East Asia and the Pacific. Originally from mainland South East Asia or East Asia, this plant was introduced into the Pacific range by prehistoric Austronesian voyagers. We used non-coding internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA and inter-simple sequence repeat (ISSR) on 79 samples of B. papyrifera from different islands of Remote Oceania, and South East Asia and East Asia. Our results show an absence of genetic diversity in the introduced range of Remote Oceania, with the sole exception of Hawaii. By contrast, Asian samples show genetic diversity. The data obtained suggest a prehistoric human-mediated introduction of this species from East Asia to Remote Oceania and a second, possibly historic, human-mediated introduction to Hawaii.

Año: 2015

Palabras claves: Asia, human-mediated dispersal, ISSR, ITS, paper mulberry, Polynesia.

Poa annua L. in the maritime Antarctic: an overview.

Chwedorzewska, K., Giełwanowska, I., Olech, M., Molina-Montenegro, M., Wódkiewicz, M., & Galera, H.

Poa annua is the only flowering plant species that has established a breeding population in the maritime Antarctic, through repeated anthropogenic introduction. The first appearance of this species in the Antarctic was observed in 1953. Annual bluegrass inhabits mainly anthropogenic sites, but recently has entered tundra communities. The functioning of P. annua in the Antarctic could not have been possible without adaptations that enable the plants to persist in the specific climatic conditions typical for this zone. Poa annua is highly adaptable to environmental stress and unstable habitats: huge phenotypic and genotypic variability, small size, plastic life cycle (life-history types ranging from annual to perennial forms). The spreading of P. annua in the Antarctic Peninsula region is a classic example of the expansion process following anthropogenic introduction of an invasive species, and illustrates the dangers to Antarctic terrestrial ecosystems that are associated with increasing human traffic.

Año: 2015

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Facilitative Effect of a Generalist Herbivore on the Recovery of a Perennial Alga: Consequences forPersistence at the Edge of Their Geographic Range.

Aguilera MA, Valdivia N, Broitman BR.

Understanding the impacts of consumers on the abundance, growth rate, recovery and persistence of their resources across their distributional range can shed light on the role of trophic interactions in determining species range shifts. Here, we examined if consumptive effects of the intertidal grazer Scurria viridula positively influences the abundance and recovery from disturbances of the alga Mazzaella laminarioides at the edge of its geographic distributions in northern-central Chilean rocky shores. Through field experiments conducted at a site in the region where M. laminarioides overlaps with the polar range edge of S. viridula, we estimated the effects of grazing on different life stages of M. laminarioides. We also used long-term abundance surveys conducted across ~700 km of the shore to evaluate co-occurrence patterns of the study species across their range overlap. We found that S. viridula had positive net effects on M. laminarioides by increasing its cover and re-growth from perennial basal crusts. Probability of occurrence of M. laminarioides increased significantly with increasing density of S. viridula across the range overlap. The negative effect of S. viridula on the percentage cover of opportunistic green algae—shown to compete for space with corticated algae—suggests that competitive release may be part of the mechanism driving the positive effect of the limpet on the abundance and recovery from disturbance of M. laminarioides. We suggest that grazer populations contribute to enhance the abundance of M. laminarioides, facilitating its recolonization and persistence at its distributional range edge. Our study highlights that indirect facilitation can determine the recovery and persistence of a resource at the limit of its distribution, and may well contribute to the ecological mechanisms governing species distributions and range shifts.

Año: 2015

Palabras claves: Algae, Fronds, Grazing, Herbivory, Plant-herbivore interactions, Species interactions, Geographic distribution,Trophic interactions.

A holistic picture of Austronesian migrations revealed by phylogeography of Pacific paper mulberry.

Chang, C., Liu, H., Moncada, X., Seelenfreund, A., Seelenfreund, D., & Chung, K.

The peopling of Remote Oceanic islands by Austronesian speakers is a fascinating and yet contentious part of human prehistory. Linguistic, archaeological, and genetic studies have shown the complex nature of the process in which different components that helped to shape Lapita culture in Near Oceania each have their own unique history. Important evidence points to Taiwan as an Austronesian ancestral homeland with a more distant origin in South China, whereas alternative models favor South China to North Vietnam or a Southeast Asian origin. We test these propositions by studying phylogeography of paper mulberry, a common East Asian tree species introduced and clonally propagated since prehistoric times across the Pacific for making barkcloth, a practical and symbolic component of Austronesian cultures. Using the hypervariable chloroplast ndhF-rpl32 sequences of 604 samples collected from East Asia, Southeast Asia, and Oceanic islands (including 19 historical herbarium specimens from Near and Remote Oceania), 48 haplotypes are detected and haplotype cp-17 is predominant in both Near and Remote Oceania. Because cp-17 has an unambiguous Taiwanese origin and cp-17–carrying Oceanic paper mulberries are clonally propagated, our data concur with expectations of Taiwan as the Austronesian homeland, providing circumstantial support for the “out of Taiwan” hypothesis. Our data also provide insights into the dispersal of paper mulberry from South China “into North Taiwan,” the “out of South China–Indochina” expansion to New Guinea, and the geographic origins of post-European introductions of paper mulberry into Oceania.

Año: 2015

Palabras claves: Broussonetia papyrifera, commensal approach, DNA of herbarium specimens, out of Taiwan hypothesis, Voyaging Corridor Triple I .

Disentangling the effects of propagule supply and environmental filtering on the spatial structure of a rocky shore metacommunity.

Valdivia, N., Aguilera, M., Navarrete, S., & Broitman, B.

Environment-driven variation in the supply of individuals to local assemblages can determine patterns of community structure. Alternatively, local environmental conditions can determine the type of species that can be successfully established in a given community. Most communities are probably found somewhere between these 2 extremes, but few studies have attempted to disentangle their effects in a community-wide context. Using multivariate approaches in rocky shore communities, we showed that environmental variables (i.e. sea surface temperature and wind stress), the benthic abundance of 108 species of invertebrates and macroalgae, and recruitment rates of invertebrates all shared significant spatial and temporal patterns of variability across a 400 km shoreline marked by the presence of a prominent upwelling centre. Variance-partition analyses for the invertebrates with pelagic development showed that spatially structured environmental filtering alone explained only 7% of the variation in community structure. In contrast, the combination of environmental conditions and recruitment variation explained 45% of the variability in community structure and an additional 18% was jointly explained by recruitment and spatial relationships among sampling sites. Unexplained variation (41%) can be attributed to factors like local species interactions that are robust to environmental variability. Therefore, environment-driven variation in recruitment rates can have, in comparison to pure environmental filtering, stronger effects on the structure of this metacommunity. Our results can serve as a foundation for predictive models of the response of biodiversity to climate change and other human-induced disturbances, which are predicted to alter local environmental conditions and dispersal pathways.

Año: 2015

Palabras claves: Metacommunity, Recruitment, Environmental filtering, Dispersal, Biodiversity, Chile, Marine, Mesoscale.

First record of the sea anemone Diadumene lineata (Verrill, 1869)from the Chilean coast.

Häussermann, V., Spano, C., Thiel, M., & Lohrmann, K.B.

The orange-striped green sea anemone Diadumene lineata (Verrill 1871) was originally described from Japan but has been recorded as an invasive species from temperate and tropical coasts all over the world, being presumably transported on ship hulls or with seafood shipments. Here, we report the occurrence of this species for the first time from the South East Pacific, specifically on the coast of Coquimbo, northern Chile. Two specimens were spotted in 2012 and approximately 15 individuals were collected and examined in 2014. Most specimens were identified both externally and internally, confirming the cnidome described for the species in several individuals. Generally, the greenish-brown specimens had a pedal disc diameter of up to 7 mm and possessed between 2 and 11 irregularly distributedorange stripes. Since D. lineata is known to proliferate quickly, it is strongly recommended to start monitoring the area for possible outbreaks.

Año: 2015

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Numbers and sizes of the shrimp Rhynchocinetes uritaiKubo, 1942 (Decapoda: Caridea) caught in bait and refuge traps.

Osawa, Y., Bauer, R., Aoki, M., & Thiel, M.

Catch rates and sizes of hingebeak shrimp Rhynchocinetes uritaiKubo, 1942 were studied with two types of traps: bait traps that were exposed for 1-2 days and unbaited “refuge traps” exposed for 2-4 weeks. Shrimp were collected twice a month from June 2010 to May 2012 on rocky substrata in Oura Bay, Shimoda, Japan. Overall the numbers of shrimp caught did not differ between the two trap types, but when adjusted for soak times, the bait traps had substantially higher catch rates than the refuge traps. Addition of light to the bait traps had no significant effect on catch rates. However, shrimp in the baited traps were significantly larger than those in the refuge traps. The results show that size distribution can be greatly affected by trap type. Consequently, using two types of traps simultaneously increases not only the catch efficiency but also ensures that all sizes of the reproductively mature shrimp population are sampled in adequate numbers, which is especially important in protandric hermaphrodites.

Año: 2015

Palabras claves: Hingebeak shrimp; bait traps; catch efficiency; refuge traps.