Macroecología de la reproducción en "Prunus lusitanica" L.: variabilidad geográfica y efectos de la marginalidad en un árbol relicto

Abstract

Depending on habitat quality, most plant species show variations in survival and reproduction. Thus, when comparing, marginal populations with populations living in optimal environments, the former should exhibit a lower reproductive performance. In this thesis, I tested this hypothesis for Prunus lusitanica L., a relict of tertiary origin. The current distribution of this species covers a wide range of environmental conditions and therefore it involves interactions with different physical and biotic factors, including anthropogenic factors. At the global scale, the populations are very dispersed and fragmented and generally live at low densities. In the Macaronesian region, an area regarded as hypothetically optimal, population sizes are greater than those in inland areas, a region considered hypothetically marginal. Sexual regeneration rates are generally low. In contrast, vegetative reproduction rates are high. These two rates are homogeneous between optimal and marginal areas, although with significant internal variability, strongly influenced by anthropogenic disturbance. There is not a trade-off between both reproductive strategies. The frugivorous community which interacts with the fruits of P. lusitanica shows a high dispersal efficiency. The birds handle the fruits properly, depositing a high proportion in favorable microhabitats for recruitment. In parallel, early recruitment is very low and is higher in optimal environments. Survival is strongly influenced by soil moisture, thus determining the final distribution of the adult individuals. Finally, all these aspects have a strong influence on the high plasticity that P. lusitanica shows across different environmental gradients.