Importancia ecológica de los mamíferos frugívoros en la dinámica de regeneración de campos abandonados en ambientes mediterráneos

A nivel global, dos tendencias opuestas gobiernan el uso de la tierra: la intensificación y el abandono. Esta última supone una oportunidad para larecuperación de los ecosistemas, una necesidad urgente dada la actual crisis ambiental. La comunidad de dispersores frugívoros es determinantepara recuperar la estructura y complejidad de la vegetación en campos abandonados, ya que éstos suelen estar desprovistos de propágulos.Recientes estudios han resaltado la especial relevancia de los mamíferos frugívoros en el proceso de dispersión de semillas en ambientesdegradados como los campos abandonados. Esto es debido a una serie de rasgos morfológicos y de comportamiento que caracterizan a losfrugívoros mamíferos y que les hace ser dispersores especialmente efectivos. Generalmente los mamíferos frugívoros tienen un mayor tamañocorporal, mayores áreas de campeo y distancias de dispersión, frecuente uso de hábitats abiertos, movilizando así más semillas hasta los camposabandonados que otros grupos de frugívoros (e.g. aves). Una vez que una semilla ha sido depositada tiene que superar las sucesivas etapas hastael establecimiento (depredación post-dispersiva, germinación, supervivencia y crecimiento). Los mamíferos frugívoros favorecen todo este procesoen mayor medida que otros dispersores. A nivel interespecífico pueden dispersar mayor diversidad de especies al estar generalmente menoslimitados por el tamaño de fruto, y a nivel intra-especifico no seleccionan semillas de pequeño tamaño. Además, suelen depositar las semillas enmicrohábitats que resultan especialmente adecuados para el reclutamiento. En consecuencia, los mamíferos son un elemento clave en los ensamblesde frugívoros que propician la regeneración de los campos abandonados y su función ecológica debe ser considerada en la restauración y manejode hábitats degradados.Palabras clave: áreas degradadas; bosque remanente; cambio de los usos del suelo; dispersión de semillas; efectividad de la dispersión; regeneración,dispersión agregad

Uncovering mechanisms of bird seed dispersal in semiarid environments to help to restore them

Mediterranean semiarid areas are suffering a growing process of agricultural abandonment that represents a challenge for restoration. Limited seed arrival, drought, and scarce suitable microhabitats in oldfields make plant colonization difficult. Restoration through ecological succession can take advantage of increased seed dispersal through animal vectors, but precise knowledge of the factors involved (e.g., seed disperser behavior, rate of effective recruitment of dispersed seeds, and effectiveness of the applied restoration structures) is critical. Otherwise, efforts to foster the processes of interest may be misdirected. We propose and test a methodological approach based on the combination of ecological (bird censuses and camera trapping) and genetic tools (DNA barcoding), to assess seed dispersal of fleshy-fruited shrub species by birds toward oldfields in one of the driest areas of southeastern Spain. We assisted natural restoration with artificial bird attractors (perches and water troughs) in two abandoned areas with different ages. Furthermore, we provided microenvironments (rocks) and prevented herbivory (by fencing) to enhance plant recruitment. Results revealed strong differences among assessment techniques in the characterization of dispersal interactions. While bird censuses only informed about frugivores occurrence, camera trapping and barcoding enabled the quantification of species responses. Attractors proved to be effective in triggering a quantifiable seed arrival, but no subsequent plant establishment occurred. We highlight the importance of implementing different techniques to characterize and assess avian seed disperser performance. Water provision increased seed arrival, but our design failed to enhance plant recruitment. The next logical step in the restoration of Mediterranean oldfields is the optimization of conditions for seed germination and successful plant establishment

A comparative analysis between SNPs and SSRs to investigate genetic variation in a juniper species (Juniperus phoenicea ssp. turbinata)

Genomic resources are a valuable research tool for understanding and forecasting the response of forest trees to global change and for developing science-based management strategies. Yet, many ecologically relevant tree species still lack such resources. The conifer genus Juniperus contains >70 species that are widely distributed through the Northern Hemisphere, including several keystone species that form extensive forests in arid landscapes. To date, single-nucleotide polymorphism (SNP) markers have not been described for this ecologically important tree genus and the few described simple sequence repeat (SSR) markers result insufficient for performing reliable population demographic inference. Here, we report on the successful development of 19 new SSR and 147 SNP markers for Phoenician juniper (Juniperus phoenicea ssp. turbinata), a species widely distributed along the coasts of the Mediterranean Basin. We calculate a series of population genetic diversity estimates for each set of markers independently and for both sets combined. Our comparison shows that the higher per-locus information content of SSRs makes them the marker of choice for parentage and assignment studies, whereas SNPs provide more reliable demographic inferences (N-e and detection of a recent bottleneck). We also test and confirm the transferability of the new set of SNP markers to the closely related tetraploid species J. thurifera. Finally, we perform an orthology analysis with two gymnosperm model species to search for SNPs linked with functional genes