Papers by Alfonso Valiente-Banuet
Revista Chilena de Historia Natural, 2018
Background: Eulychnia acida is an endemic Chilean cactus species whose fruits show several traits... more Background: Eulychnia acida is an endemic Chilean cactus species whose fruits show several traits that, taken as a whole, are compatible with a seed dispersal syndrome by large herbivore vertebrates. Since only a few large native mammals exist in Chile at present, cactus fruit consumption and seed dispersal may be coopted by introduced mammals as predicted by Janzen and Martin's (1982) hypothesis for tropical ecosystems. Findings: We describe the current frugivore species of E. acida in a protected semiarid-Mediterranean ecosystem using field measurements and feeding experiments. In addition, to examine a potential role as seed dispersers of the cactus species, we offered fruits and performed germination tests on seeds defecated by Lama guanicoe and the introduced goat Capra a. hircus under captivity conditions. Our data indicate that while fruits of E. acida are pecked by the Chilean tinamou, Nothoprocta perdicaria, and the Chilean mockingbird, Mimus thenca, and eaten by the brush-tailed rodent, Octodon degus, none of these species could be considered a legitimate seed disperser. Unlike L. guanicoe, the goat C. a. hircus did not reduce seed germination, having a neutral effect. Conclusions: Results from this study indicate that introduced C. a. hircus was the only species showing a potential role in the seed dispersal process of E. acida. In the absence of native frugivore species, goats might play an important role in population recruitment of the endemic cactus. These results extend Janzen and Martin's (1982) anachronism hypothesis to the Chilean Mediterranean ecosystem.
Functional Ecology, 2016
1. Plant facilitation assembles functionally contrasted communities in dry lands. Nurse plants ar... more 1. Plant facilitation assembles functionally contrasted communities in dry lands. Nurse plants are often early colonizers with xerophytic traits that were mostly selected during the dry Quaternary (Quaternary syndrome), while beneficiary plants tend to be late-successional species with mesophytic traits that evolved mainly during the more humid Tertiary (Tertiary syndrome). Integrating plant facilitation within the community assembly theory requires a better understanding of the ontogenetic development of the nursing abilities that benefit functionally contrasted species. 2. We assessed whether the same nurse plant facilitates species with Quaternary and Tertiary syndromes in an ecosystem under severe abiotic stress conditions imposed by aridity and gypsum soil toxicity. We hypothesized that both functional types find suitable microsites for seedling establishment underneath the same nurse but their optimal regeneration niches are temporally segregated along the ontogenetic development of the nurse. 3. We carried out a sowing experiment along a 40-year ontogenetic gradient of the nurse shrub Ononis tridentata. Seeds from five Tertiary and five Quaternary species were sown and seedling emergence monitored. 4. While the nurse age did not affect the seedling emergence of Quaternary species, it significantly increased that of Tertiary species. These results were corroborated for elder ontogenetic stages in non-manipulated plants in the field. Juveniles of Quaternary species were able to grow beneath nurse plants along their whole ontogenetic gradient excepting beneath Ononis seedlings, while Tertiary species were only facilitated by mature nurses. 5. Synthesis. Our results show that plant nursing abilities evolve ontogenetically in a different way for beneficiary Quaternary and Tertiary plant lineages. The finding of a plant species that plays a role as key assembler of early-and late-successional species in plant dynamics broadens the scope of facilitation in the community assembly theory.
American Journal of Botany, 1999
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Ponencia presentada en el 12th European Ecological Federation Congress celebrado en Avila del 25 ... more Ponencia presentada en el 12th European Ecological Federation Congress celebrado en Avila del 25 al 29 de septiembre de 2011
Acta Zoológica …, 2004
Las hormigas son consideradas un elemento central en las zonas áridas debido principalmente a su ... more Las hormigas son consideradas un elemento central en las zonas áridas debido principalmente a su papel como estructuradoras de las comunidades de plantas y por las diversas interacciones que establecen con otros organismos. Sin embargo, el conocimiento sobre la diversidad de las hormigas en las zonas áridas mexicanas es escaso. En este trabajo estudiamos la mirmecofauna de una localidad ubicada en el Valle semiárido de Tehuacán (San Rafael Coxcatlán). Nuestros objetivos fueron estimar la riqueza de especies de hormigas en este sitio y obtener un listado más extenso del Valle de Tehuacán, combinando nuestros datos con los de otro estudio. Finalmente comparamos la riqueza de especies de Tehuacán con la de otras dos zonas áridas mexicanas (Mapimí, Durango, en el Desierto Chihuahuense y Los Horcones, Sonora, en el Desierto Sonorense). Las hormigas de San Rafael Coxcatlán se colectaron entre noviembre de 1999 y enero de 2001 usando trampas "pitfall". Se colectaron 28 especies pertenecientes a 14 géneros en cinco subfamilias, una riqueza relativamente alta para una zona tan pequeña (5 km²). Un análisis de conglomerados indicó que la mirmecofauna de Los Horcones y la del Valle de Tehuacán fueron las más similares. Ambos sitios además de compartir especies de amplia distribución, también comparten algunas de afinidad tropical tales como Pseudomyrmex major y Camponotus atriceps. Se han reportado patrones similares para la vegetación, aves y mamíferos de estos dos sitios los cuales han indicado que varios géneros de afinidad tropical se comparten. Este estudio representa uno de los primeros esfuerzos por conocer la diversidad de hormigas de una zona árida del centro de México.
PLOS ONE
'Mexical' scrubland is a sclerophyllous evergreen Mediterranean-like vegetation occurring in the ... more 'Mexical' scrubland is a sclerophyllous evergreen Mediterranean-like vegetation occurring in the leeward slopes of the main Mexican mountain ranges, under tropical climate. This biome occupies an elevational range approximately from 1900 to 2600 meters above sea level, which frequently is the uppermost part of the mountains range. This puts it at risk of extinction in a scenario of global warming in which an upward retraction of this type of vegetation is expected. The Mexical remains one of the least studied ecosystems in Mexico. For instance, nothing is known about pollinator fauna of this vegetation. Our main objective is to make a first insight into the taxonomic identity of the bee fauna that inhabits this biome, and to study how it is distributed along the elevational gradient that it occupies. Our results highlight that elevation gradient negatively affects bee species richness and that this relationship is strongly mediated by temperature. Bee abundance had no significant pattern along elevational gradient, but shows a significant relationship with flower density. Interestingly, and contrary to previous works, we obtained a different pattern for bee richness and bee abundance. Bee community composition changed strongly along elevation gradient, mainly in relation to temperature and flower density. In a global warming scenario, as temperatures increases, species with cold preferences, occupying the highest part of the elevation gradient, are likely to suffer negative consequences (even extinction risk), if they are not flexible enough to adjust their physiology and/or some life-story traits to warmer conditions. Species occupying mid and lower elevations are likely to extend their range of elevational distribution towards higher ranges. This will foreseeably cause a new composition of species and a new scenario of interactions, the adjustment of which still leaves many unknowns to solve.
Proceedings of the National Academy of Sciences of the United States of America, Jan 10, 2009
Many studies have shown that individuals from invasive populations of many different plant specie... more Many studies have shown that individuals from invasive populations of many different plant species grow larger than individuals from native populations and that this difference has a genetic basis. This increased vigor in invasive populations is thought to be due to life history tradeoffs, in which selection favors the loss of costly defense traits, thereby freeing resources that can be devoted to increased growth or fecundity. Despite the theoretical importance of such allocation shifts for invasions, there have been no efforts to understand apparent evolutionary shifts in defense-growth allocation mechanistically. Reallocation of nitrogen (N) to photosynthesis is likely to play a crucial role in any growth increase; however, no study has been conducted to explore potential evolutionary changes in N allocation of introduced plants. Here, we show that introduced Ageratina adenophora, a noxious invasive plant throughout the subtropics, appears to have evolved increased N allocation t...
Revista chilena de historia natural, 2002
An analysis of the degree of vulnerability of the pollination systems of Mexican columnar cacti s... more An analysis of the degree of vulnerability of the pollination systems of Mexican columnar cacti showing a chiropterophyllous pollination syndrome was conducted, assuming that specialized pollination interactions would be more vulnerable to human perturbations. The results indicate that the species inhabiting the northern distribution limit of the columnar cacti show generalized pollination systems whereas species inhabiting central Mexico showing specialized pollination interactions would be more vulnerable to perturbations. This contrasting geographic pattern might be related to the migratory movements of the nectar-feeding bats in the northern limit of distribution of the columnar cacti that restricted local specialization, whereas resident nectar-feeding bat populations in south-central Mexico probably favored local specialization.
Journal of Arid Environments, 1997
In the neotropics, central Mexico and Venezuela, columnar cacti (mostly belonging to tribe Pachyc... more In the neotropics, central Mexico and Venezuela, columnar cacti (mostly belonging to tribe Pachycereae) are pollinated mainly by bats. In the Tehuacán Valley 36 species of columnar cacti have their blooming peak almost simultaneously between April and June, and species with chiropterophilous pollination have been shown to be self-incompatible, fruiting only after bat pollination. Nectarivorous bats are abundant also during spring and summer, and migrate during autumn and winter. Two columnar cacti, Pachycereus weberi (tribe Pachycereae) and Pilosocereus chrysacanthus (tribe Cereae), flower during winter and early spring facing an apparent scarcity of bats. We hypothesized that under this condition, these plants may resemble the columnar cacti in extratropical deserts where both bats and diurnal vectors can effect seed production. However, we found that these two plant species have white, long tubular flowers, are nocturnal, self-incompatible and produce fruits only after the visitation of four nectar-feeding bats and two frugivorous bats. We found that nectar-feeding bats have a small resident population in the Valley. In addition these cacti species grow along possible routes of bat altitudinal migration. A long, and possibly variable flowering season may be also related to low pollen vector density.
Journal of Ecology, 2010
1. Ecological communities are assembled as complex networks of both positive (i.e. facilitation) ... more 1. Ecological communities are assembled as complex networks of both positive (i.e. facilitation) and negative (i.e. competition) interactions. In networks established among plant species, many facilitative interactions occurring between a benefactor -a nurse -and a beneficiary -a facilitated seedling -turn into competition over time as the facilitated seedling grows and outcompetes the nurse. The facilitative associations that disappear over time are mainly restricted to closely related taxa, because close relatives tend to share niche requirements and compete more strongly for the same resources. In consequence, the phylogenetic structure of a network might change as positive associations become negative. 2. This study is aimed to characterize how the overall (i.e. nestedness and connectance) and the phylogenetic structure of facilitation networks in semi-arid communities change when facilitation turns into competition and some of the early species associations established by facilitation disappear. 3. We show that the initial facilitation networks retain the overall, but not the phylogenetic, structure. Phylogenetic analyses show that as seedlings, facilitated species tend to associate with the same subset of nurses while, on the contrary, nurses are indifferent to the identity of their facilitated seedlings. But when competition becomes important, closely related nurse species appear associated with only a subset of facilitated species in the community. 4. Synthesis. Temporal rearrangements in the phylogenetic structure of the facilitation networks provide evidence that plant-plant species interactions lead to highly species-specific networks in which the phylogenetic history has a pervasive influence not only on recruitment but also on adult community composition. The use of phylogenetic methods combined with complex network approaches opens the possibility to understand the complexity of ecological interactions occurring in nature as for example those occurring when biological invasions take place or those producing coextinction cascades following species removal from ecosystems.
Encyclopedia of the World's Biomes
Heliyon
The morphological evolution of the basins in the Sierra Madre del Sur (SMS), southern M exico is ... more The morphological evolution of the basins in the Sierra Madre del Sur (SMS), southern M exico is poorly understood. This work explains for the first time the geomorphological development of the tectonic, fluviallyinterconnected SMS basins named San Juan Raya (SJRb) and Zapotitl an (ZAPb). The evolution of the SJRb and ZAPb are analysed within the context of the transformations of the well-studied Tehuac an basin (TEHb). A new interpretation of a series of tectonic features of the TEHb valley area is also presented. Published geological data and extensive field work provided the basis for our geomorphological and evolutionary interpretation of basin evolution of this part of Mesoamerica during the late Cenozoic. Stratigraphic and sedimentary records suggest that after the late Cretaceous-early Cenozoic orogeny the TEHb and ZAPb were closed basins, and that the TEHb graben system was activated during the Paleogene as a response to the dominant regional NW-SE trending faults. We propose that the ZAPb and SJRb formed sequentially during the Neogene as a result of new E-W, N-S and NE-SW faults. The continuation of the TEHb extension during the Oligocene widened its lowland area and allowed the formation of an extensive lake. No alluvial or fluvial records of this interval are found in the ZAPb and SJRb. No sedimentation rather than formation and subsequent erosion of such sediments is supported by the basin morphology and by the absence of re-worked alluvial deposits at the outlet area where both connect to the TEHb. By middle to late Miocene the TEHb lost its endorheic configuration, ending the lake-type deposition while new faults initiated the opening of the ZAPb. Intensive tectonics, alluvial deposition and the confinement of the Tehuac an lake to the north sector of this basin characterised the Pliocene. During the late Pliocene to the early Pleistocene the formation of the SJRb was initiated. Quaternary faulting related to basin extension along the north watershed of the SJRb and ZAPb is supported by independent data on the biogeography of the cactus Mammillaria pectinifera. We introduce the idea that the departure from the regional NW-SE fault alignment that formed the major Miocene basins to a more local E-W trend that formed Neogene-Quaternary basins was probably a response to the latest post-orogenic relaxation of the crust in the Mixteca terrane.
Revista Mexicana de Biodiversidad
Resumen En este estudio se analiza por primera vez la lluvia de polen en la selva baja caducifoli... more Resumen En este estudio se analiza por primera vez la lluvia de polen en la selva baja caducifolia del cerro El Picante en San José Tilapa (Puebla), ubicado dentro del biodiverso valle de Tehuacán-Cuicatlán. En 3 transectos de 100 m cada uno, se recolectaron bromelias cada 10 m, obteniéndose un total de 32 muestras, de las cuales se recuperaron los palinomorfos y se procesaron por medio de la técnica de acetólisis. Un total de 11,520 polen-esporas pertenecientes a 156 grupos taxonómicos fueron registrados. Los análisis permitieron reconocer taxones regionales, locales y extra locales identificados como señales polínicas. La señal regional estuvo caracterizada por elementos templados, principalmente del bosque mesófilo. La señal local destacó en riqueza e incluyó Asteraceae, Bursera morelensis, B. aptera, Euphorbiaceae, Ceiba aesculifolia y C. parvifolia de la selva baja caducifolia del cerro El Picante; mientras que la señal extra local estuvo representada por Sapindaceae, Caryophyllaceae, Meliaceae y Ephedra spp., que son elementos tanto de selva baja caducifolia como de matorral xerófilo. La comparación de los conjuntos palinológicos con la estructura de la selva baja caducifolia indicaron que Acaciella sp., Asteraceae, Bursera aptera, B. morelensis, Ceiba aesculifolia, C. parvifolia y Mimosa spp. son indicadores polínicos de este tipo de vegetación.
Molecular Ecology Resources
Co‐occurrence network analysis based on amplicon sequences is increasingly used to study microbia... more Co‐occurrence network analysis based on amplicon sequences is increasingly used to study microbial communities. Patterns of co‐existence or mutual exclusion between pairs of taxa are often interpreted as reflecting positive or negative biological interactions. However, other assembly processes can underlie these patterns, including species failure to reach distant areas (dispersal limitation) and tolerate local environmental conditions (habitat filtering). We provide a tool to quantify the relative contribution of community assembly processes to microbial co‐occurrence patterns, which we applied to explore soil bacterial communities in two dry ecosystems. First, we sequenced a bacterial phylogenetic marker in soils collected across multiple plots. Second, we inferred co‐occurrence networks to identify pairs of significantly associated taxa, either co‐existing more (aggregated) or less often (segregated) than expected at random. Third, we assigned assembly processes to each pair: patterns explained based on spatial or environmental distance were ascribed to dispersal limitation (2%–4%) or habitat filtering (55%–77%), and the remaining to biological interactions. Finally, we calculated the phylogenetic distance between taxon pairs to test theoretical expectations on the linkages between phylogenetic patterns and assembly processes. Aggregated pairs were more closely related than segregated pairs. Furthermore, habitat‐filtered aggregated pairs were closer relatives than those assigned to positive interactions, consistent with phylogenetic niche conservatism and cooperativism among distantly related taxa. Negative interactions resulted in equivocal phylogenetic signatures, probably because different competitive processes leave opposing signals. We show that microbial co‐occurrence networks mainly reflect environmental tolerances and propose that incorporating measures of phylogenetic relatedness to networks might help elucidate ecologically meaningful patterns.
New Phytologist
•The tendency of closely related plant species to share natural enemies has been suggested to lim... more •The tendency of closely related plant species to share natural enemies has been suggested to limit their co-occurrence and performance, but we lack a deep understanding on how mutualistic interactions such as the mycorrhizal symbiosis affect plant-plant interactions depending on the phylogenetic relatedness of the interacting plants. We hypothesize that the effect of the mycorrhizal symbiosis on plant-plant facilitative interactions depends on the phylogenetic distance between the nurse and facilitated plants. •A recently published meta-analysis compiled the strength of plant facilitative interactions in the presence or absence (or reduced abundance) of mycorrhizal fungi. We use phylogenetically informed Bayesian linear models to test whether the effect size is influenced by the phylogenetic distance between the plant species involved in each plant facilitative interaction. •Conspecific facilitative interactions are more strongly enhanced by mycorrhizal fungi than interactions between closely related species. In heterospecific interactions, the effect of the mycorrhizal symbiosis on plant facilitation increases with the phylogenetic distance between the nurse and facilitated plant species. •Our result showing that the effect of mycorrhizal symbiosis on the facilitation interactions between plants depends on their phylogenetic relatedness provides new mechanisms to understand how facilitation is assembling ecological communities. This article is protected by copyright. All rights reserved.
Journal of Arid Environments
Abstract In facilitative interactions, facilitated plants gain a benefit from growing associated ... more Abstract In facilitative interactions, facilitated plants gain a benefit from growing associated to a nurse plant, without damaging the nurse. The persistence of these positive interactions or their shift to competition might depend on whether the nurse shrub also gains some benefit from the association. We hypothesized that nurse shrubs can receive water stored in the parenchyma of their facilitated Neobuxbaumia tetetzo once the cactus becomes an adult. We injected deuterium-enriched water into the water storage tissues of N. tetetzo adults, and sampled the xylem water of the nurse Mimosa luisana plant in the shared vegetation patch before and after the injection of the tracer. We also sampled spatial-control individuals of M luisana outside the vegetation patch. We found a significant enrichment in deuterium concentration in the xylem water of the associated M. luisana but not in individuals outside the patch. This suggests that in semiarid environments, nurse plants can benefit from growing associated to succulent columnar cacti by gaining water transferred from their storage tissues during dry periods, potentially enhancing persistence of facilitative interactions.
The Open Biology Journal
Effectiveness of seed dispersal by different species that feed on the fruits of Myrtillocactus ge... more Effectiveness of seed dispersal by different species that feed on the fruits of Myrtillocactus geometrizans was evaluated, considering both quantity and quality of dispersal, in a patch of tropical deciduous forest in Zapotitlán de las Salinas. Effectiveness was estimated to be strongly influenced by the post-foraging movements of the frugivores, leading us to suggest that the quality component of seed dispersal occupies a central role in the assessment of disperser effectiveness and to expect that dispersers that stay in the tropical deciduous forest patch after foraging would have highest effectiveness. Birds were the principal dispersers of M. geometrizans. This was particularly true of Phainopepla nitens, since this species showed a high fidelity within the tropical deciduous forest. These observations emphasize that it is important to determine the post-foraging habits of seed dispersers that may move across vegetation patches over the landscape in order to obtain a complete as...
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Papers by Alfonso Valiente-Banuet