Systematics of Senecio sect. Crociseris (Compositae, Senecioneae)

Se revisa taxonómicamente Senecio sect. Crociseris (Compositae, Senecioneae),una de las cuatro principales secciones del género en el ámbito de Eurasia y el norte de África. Este grupo comprende hierbas rizomatosas, distribuidas principalmente del oeste de Europa y noroeste de África al oeste asiático, y presenta la mayor diversidad en el Mediterráneo septentrional. El nuevo tratamiento taxonómico que se propone reconoce 28 especies y 8 subespecies. Se ha hecho un especial esfuerzo en el análisis de la variabilidad del gr. S. doronicum, cuya sistemática ha sido objeto de controversia durante mucho tiempo. En este grupo se aceptan tres especies: S. doronicum, S.lagascanus, y S. provincialis, la primera con tres subespecies: subsp. doronicum, subsp.longifolius, y subsp. orientalis. Con el objetivo de indagar en las relaciones de las especies dentro de la sección y de ésta con otros grupos de Senecio, se han llevado a cabo análisis filogenéticos basados en secuencias ITS y de cloroplasto. Los resultados sugieren que la sect. Crociseris es un grupo parafilético, ya que incluye las especies secuenciadas de la sect. Doria. Además, complejos patrones de algunas secuencias ITS sugieren eventos de hibridación. Como resultado del estudio taxonómico se proponen las siguientes combinaciones: Senecio doronicum subsp. longifolius(Willk.) J. Calvo, Senecio doronicum subsp. orientalis (Ten.) J. Calvo, Senecio macedonicus subsp. barckhausiaefolius (Boiss. & Heldr.) J. Calvo, y Senecio racemosus subsp. kirghisicus(DC.) J. Calvo. Por otro lado, S. ruthenensis de Francia y S. lusitanicus de Portugal han sido sinonimizados a S. lagascanus, así como S. ovatifolius, S. pisidicus y S. tmoleus de Anatolia a S. kolenatianus, S. olympicus, y S. castagneanus respectivamente, S.bertramii de Líbano a S. cilicius, y S. delbesianus de Siria a S. racemosus subsp. racemosus. Se han lectotipificado setenta y cinco nombres, y neotipificado S. pyrenaicus y S. scopolii. Senecio gerardi Godr., S. doronicum (L.) L. y S. paucifolius S.G. Gmel. se propusieron a conservar. Se incluyen claves de identificación, descripciones detalladas, mapas de distribución e ilustraciones. Nueve táxones han sido ilustrados por primera vez.

The comparative effectiveness of rodents and dung beetles as local seed dispersers in Mediterranean oak forests

The process of seed dispersal of many animal-dispersed plants is frequently mediated by a small set of biotic agents. However, the contribution that each of these dispersers makes to the overall recruitment may differ largely, with important ecological and management implications for the population viability and dynamics of the species implied in these interactions. In this paper, we compared the relative contribution of two local guilds of scatter-hoarding animals with contrasting metabolic requirements and foraging behaviours (rodents and dung beetles) to the overall recruitment of two Quercus species co-occurring in the forests of southern Spain. For this purpose, we considered not only the quantity of dispersed seeds but also the quality of the seed dispersal process. The suitability for recruitment of the microhabitats where the seeds were deposited was evaluated in a multi-stage demographic approach. The highest rates of seed handling and predation occurred in those microhabitats located under shrubs, mostly due to the foraging activity of rodents. However, the probability of a seed being successfully cached was higher in microhabitats located beneath a tree canopy as a result of the feeding behaviour of beetles. Rodents and beetles showed remarkable differences in their effectiveness as local acorn dispersers. Quantitatively, rodents were much more important than beetles because they dispersed the vast majority of acorns. However, they were qualitatively less effective because they consumed a high proportion of them (over 95%), and seeds were mostly dispersed under shrubs, a less suitable microhabitat for short-term recruitment of the two oak species. Our findings demonstrate that certain species of dung beetles (such as Thorectes lusitanicus), despite being quantitatively less important than rodents, can act as effective local seed dispersers of Mediterranean oak species. Changes in the abundance of beetle populations could thus have profound implications for oak recruitment and community dynamics.