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Contemporary defaunation has profound ecological consequences ranging from local or even global co-extinctions of interacting species to the loss of ecosystem functions and services critical for humanity. Other components of global change (climate change, introduced pests, land use changes) are also harming ecosystem functioning by augmenting tree mortality worldwide. Defaunation and increased tree mortality often coincide in many human-altered ecosystems but whether they interact, leading to non-additive effects on ecosystem functioning, remains largely unknown. However, under some ecological circumstances, the decline or extirpation of one species due to defaunation can be neutralized by increases in the abundance of some functionally similar species (i.e. ‘density compensation’). We combined long-term field data with individual-based modelling to investigate the potential interactive effects of seed disperser loss, increased tree mortality and density compensation on seed dispersal in a heterogeneous landscape. Our simulation experiments showed that both stressors markedly limit not only the quantity of seed dispersal but also its quality since the impact on seed dispersal strongly varied among habitat types that differ strikingly in suitability for tree establishment. Density compensation had a marked positive effect on seed dispersal which, however, was largely limited under increased tree mortality. The combined negative effects of defaunation and increased tree mortality on seed dispersal were lower than the expected additive effect. This highlights the need to account for the joint operation of multiple stressors to accurately predict the impacts of global change on the link between biodiversity and ecosystem functioning

Investigating spatial variation in the relative importance of sexual reproduction and clonal propagation is critical to obtain more accurate estimates of future effective population sizes and genetic diversity, as well as to identify ecological correlates of clonality. We combined a stratified sampling scheme with microsatellite genetic analyses to estimate variation in the proportion of sexual versus clonal recruits among saplings in five populations of the tree Pyrus bourgaeana. Using a likelihood framework, we identified clones among the genotypes analysed and examined variation among populations regarding the proportion of saplings coming from clonal propagation. We also examined the relationship between the relative abundance of clonal shoots across the studied populations and their herbivory levels. Our results revealed that one third of the saplings examined (N = 225 saplings) had a probability above 0.9 of being clones of nearby (, A.R.C. was supported by the post-doctoral fellowship SFRH/BPD/115781/2016 from the Portuguese Foundation for Scienceand Technology (FCT). J.M.F. was funded by the Investigator Programme (IF/00728/2013) from the Foundation for Scienceand Technology (FCT).

The combined effect of climate change and habitat destruction and fragmentation threatens many plant populations and even entire communities in Mediterranean ecosystems. The Iberian pear, Pyrus bourgaeana Decne, a characteristic species of Mediterranean ecosystems, is threatened by both habitat and climate changes. We ask whether and how the growth of mature P. bourgaeana in the thermo-Mediterranean zone (i.e., altitude

Arenas-Castro, S., Fernandez-Haeger, J., Jordano-Barbudo, D. 2015. Structure of ages, sizes and growth in a local population of the Iberian wild pear (Cordoba, Spain). Ecosistemas 24(2): 7-14. Doi.: 10.7818/ECOS.2015.24-2.02 In recent decades, the remarkable proliferation of dendrochronological studies in Spain has contributed significantly to advancing knowledge of the structure and dynamics of forests. However, researches have focused mainly on forest species of greatest interest, to the detriment of other species which have a greater ecological interest. A paradigmatic case is the Iberian wild pear ( Pyrus bourgaeana , D), a virtually unknown species from the ecological point of view, although classified as characteristic species of Mediterranean ecosystems. In order to describe the population structure of this species, through the tree-rings analysis we obtained the age and size of 122 individuals with DBH > 5 cm, located in two adjacent areas (abandoned olive grove and meadows of Oaks or dehesa) in Sierra Morena (Cordoba, Spain). The mean age of trees was ≈ 37±12 years, the oldest was 80, and the tree sizes were highly different, between 10 and 35 cm. Trunk diameter was not a good predictor of the tree-age, because even we found very striking differences in the age and trunk diameter relationship between closely spaced trees. Both age and growth-rates of trees in the abandoned olive grove were significantly higher than in the trees of the Dehesa. These differences could be related to the management history conducted in the study area during the last 50 years, because there are no negative density-dependent effects on growth-rates.

Tree-ring analysis is a basic technique of paramount importance in forest management, yet it may prove difficult and time-consuming for many slow-growth hardwood tree species. Moreover, it requires the use of specialized tools and proprietary software, which may hinder researchers working with limited budgets. We describe an innovative and inexpensive method using DIVA-GIS freeware software to analyze true color high-resolution scanned images of cores previously enhanced with ImageJ freeware (GIS-SDI), and test its accuracy against the widely-used LINTAB-TSAPWin™ and WinDENDRO™ methods. For this purpose, Abies pinsapo and Pyrus bourgaeana increment cores were processed independently using each of the three methods and the results were statistically compared. Dating results were consistent across all three methods, although identifying rings was easier and quicker to perform on the digital images. Using a modern but affordable flatbed scanner to digitize tree cores and the free DIVA-GIS software t...

Durante las últimas décadas, la notable proliferación de estudios dendrocronológicos en España ha contribuido significativamente al avance del conocimiento de la estructura y dinámica de las masas forestales. Sin embargo, las investigaciones realizadas se han centrado principalmente en especies de mayor interés forestal, en detrimento de otras que sin embargo presentan un notable interés ecológico. Un caso paradigmático es el piruétano (Pyrus bourgaeana, D), especie virtualmente desconocida desde el punto de vista ecológico, aunque tipificada como especie característica de los ecosistemas Mediterráneos. Con objeto de describir la estructura poblacional de esta especie, a través del análisis de los anillos de los árboles obtuvimos la edad y tamaño de 122 individuos con DAP > 5 cm, localizados en dos zonas adyacentes (olivar abandonado y dehesa de encinas) en Sierra Morena (Córdoba, España). La edad media de los individuos fue de ≈ 37±12 años, siendo el más longevo de 80 años, y el tamaño de los árboles fue muy variable, entre 10 y 35 cm. El diámetro del tronco no fue un buen predictor de la edad de los árboles, ya que incluso encontramos diferencias muy llamativas en la relación diámetro de tronco-edad entre árboles muy próximos. Tanto la edad como la tasa de crecimiento de los piruétanos del olivar abandonado, fueron significativamente mayores que en los árboles de la dehesa. Estas diferencias podrían estar relacionadas con la historia de manejo llevada a cabo en el área de estudio durante los últimos 50 años, ya que no existen efectos negativos denso-dependientes sobre la tasa de crecimiento In recent decades, the remarkable proliferation of dendrochronological studies in Spain has contributed significantly to advancing knowledge of the structure and dynamics of forests. However, researches have focused mainly on forest species of greatest interest, to the detriment of other species which have a greater ecological interest. A paradigmatic case is the Iberian wild pear (Pyrus bourgaeana, D), a virtually unknown species from the ecological point of view, although classified as characteristic species of Mediterranean ecosystems. In order to describe the population structure of this species, through the tree-rings analysis we obtained the age and size of 122 individuals with DBH > 5 cm, located in two adjacent areas (abandoned olive grove and meadows of Oaks or dehesa) in Sierra Morena (Cordoba, Spain). The mean age of trees was ≈ 37±12 years, the oldest was 80, and the tree sizes were highly different, between 10 and 35 cm. Trunk diameter was not a good predictor of the tree-age, because even we found very striking differences in the age and trunk diameter relationship between closely spaced trees. Both age and growth-rates of trees in the abandoned olive grove were significantly higher than in the trees of the Dehesa. These differences could be related to the management history conducted in the study area during the last 50 years, because there are no negative density-dependent effects on growth-rates

Pulp feeders usually ingest fruit rewards without dispersing their seeds, and thus are considered to be mainly cheaters or thieves of seed-disperser mutualisms. By consuming the pulp, however, they could release seeds from its inhibitory effect, enhancing germination, and potentially, subsequent seedling emergence, growth, survival, and thus local recruitment. We experimentally showed that pericarp removal of Pyrus bourgaeana fruits by rabbits, Oryctolagus cuniculus, had a consistent strong positive effect on both seed performance and seedling fate. Specifically, the probability of recruitment for depulped seeds was from 4 to 25 times higher than for seeds in whole ripe fruits. Because “thieves” and “mutualists” merely refer to the extremes of a complex continuum, the persistent language of mutualist vs. thieves, cheaters, or exploiters, might be misleading.

La dispersión de semillas por animales es una interacción clave en la dinámica poblacional y la evolución de numerosos linajes vegetales. Gracias a los dispersantes, las semillas son transportadas a cierta distancia de la planta que las produce. Según la hipótesis de escape de Janzen y Connell, este alejamiento del entorno materno supone una mayor probabilidad de supervivencia y establecimiento, ya que las semillas y las plántulas son capaces de eludir el ataque de ciertos depredadores y disminuir la competencia intraespecífica, lo que se traduce en un sustancioso aumento en fitness para la planta. Con el fin de analizar el posible papel positivo de los dispersantes en el reclutamiento temprano (emergencia y supervivencia de plántulas) en el contexto de la hipótesis de escape, se seleccionaron el piruétano y el palmito, que son dispersados fundamentalmente por el tejón en el P. N. de Doñana. Ambas especies difieren en sus adaptaciones al clima mediterráneo y, por lo tanto, cabría esperar que los factores que afectan a su reclutamiento fuesen diferentes. Para comprobarlo se ha comparado tanto la emergencia como la supervivencia de plántulas bajo planta madre y en letrinas (semillas dispersadas), y bajo dos tratamientos (con y sin herbívoros). Los resultados sugieren que la supervivencia de plántulas por entorno (madre o letrina) difiere entre especies, pero que la principal causa de mortalidad de plántulas para ambas es la herbivoría, por lo que se ven influidas por la alta carga de herbívoros presente en el P. Nacional. Esto eleva la importancia de dispersantes a larga distancia como el tejón que, pese a encontrarse en bajas densidades, pueden estar realizando una labor ecosistémica importante al facilitar la colonización de nuevos hábitats y la conexión genética entre poblaciones. No obstante, se necesitan estudios a más largo plazo para poder caracterizar esta función ecosistémica con mayor precisión

El peral silvestre (Pyrus bourgaeana; Decne, 1871-72), también conocido como piruétano o guadapero, es uno de los cuatro perales silvestres espinosos presentes en España. Es un arbusto o árbol de pequeño tamaño perteneciente a la subfamilia Pomoideae y a la familia Rosaceae, que suele alcanzar de 5 a 6 metros de altura (excepcionalmente los 10 metros), caducifolio, de copa amplia e irregular, y frecuentes espinas. Los perales silvestres proporcionan valiosos recursos tróficos en forma de hojas suculentas y, más importantes, grandes cosechas de frutos durante la sequía del verano, que son consumidos por una gran variedad de mamíferos, así como varias especies de aves. P. bourgaeana desempeña un papel importante en el ecosistema y por tanto podría considerarse como una especie ¿clave¿. A pesar de esto, la biología y ecología de esta especie es poco conocida. En este sentido, la actual situación de cambio global, la acelerada pérdida de diversidad biológica acaecida en todo el mundo y el escaso conocimiento sobre la biología de P. bourgaeana, lo colocan como objetivo de estudio, para mejorar la gestión de esta planta leñosa desde el punto de vista de su conservación. En esta tesis, se cartografió la distribución conocida de la especie y además se desarrolló un modelo de distribución potencial (Species distribution models, SDM) usando datos de ocurrencia y variables climáticas y topográficas como predictores (Capítulo I). A una mayor escala de detalle, se analizó la estructura de los individuos de P. bourgaeana de una población concreta, en este caso un área de unas 230 has de Sierra Morena, en la provincia de Córdoba. Para ello, se desarrolló una nueva técnica de análisis para la medición y datación de los anillos de crecimiento de los árboles, cuya efectividad se comparó con las técnicas más clásicas de dendrocronología (Capitulo II). Esto permitió conocer la estructura demográfica de la población (Capítulo III), así como describirla desde el punto de vista morfológico y funcional (Capítulo IV). Por otro lado, se investigó la estructura y distribución espacial de esta población de peral silvestre (Capítulo V), ya que podría relacionarse con los distintos manejos a que en el pasado reciente han sido sometidas las áreas donde aparece esta población. Finalmente, se llevó a cabo un estudio exhaustivo en el que evaluamos la aplicación de la teledetección sobre imágenes de satélite y fotogramas aéreos, con objeto de distinguir y mapear perales silvestres sobre grandes zonas de dehesa o matorral de difícil acceso (Capítulo VI).

The persistence of mutualisms despite the strong incidence of exploiters could be explained if exploiters deny one or more services (i.e., cheat) while eventually supplying some subtler but critical services. Pulp feeders usually ingest fruit reward without dispersing seeds and thus are considered to be mainly cheaters or thieves of seed-disperser mutualisms. By consuming the fruit pulp, however, they could release seeds from pulp inhibitory effect, enhancing germination and, potentially, subsequent seedling emergence, growth, survival, and thus local recruitment. We evaluated such a largely neglected hypothesis by considering the interaction between Pyrus bourgaeana and its pulp feeders. We experimentally showed that pericarp removal had a consistent strong positive effect on seed performance (e.g., lower rotting and higher germination percentages) and seedling fate (greater emergence, growth, and survival to two years old). Interestingly, these relatively large positive effects of depulpation on plant fitness persisted for a surprisingly long time. Though seedlings experienced higher mortality under fruiting conspecifics, the benefits of depulpation were not overridden by high propagule mortality beneath fruiting trees or in adverse microhabitats after two years of monitoring. Specifically, the cumulative probability of establishment for depulped seeds was 4–25 times higher than for seeds in whole ripe fruits. Thus, under some circumstances, pulp feeders can provide essential services to endozoochorous plants. Our study contributes to clarifying the apparent paradox of plant–frugivore mutualisms that persist in the face of exploitation by pulp feeders. Because ‘‘thieves’’ and ‘‘mutualists’’ refer to the extremes of a complex continuum, and because organisms displaying concurrent cheating and honest behaviors during different host stages are likely prevalent, the persistent language of mutualists vs. thieves, cheaters, or exploiters might be misleading.

Flower characteristics have been traditionally considered relatively constant within species. However, there are an increasing number of examples of variation in flower characteristics. In this study, we examined the var- iation in attracting and rewarding flower characters at several ecological levels in a metapopulation of Pyrus bourgaeana in the Don˜ ana area (SW Spain). We answered the following questions: what are the variances of mor- phological and nectar characters of flowers? How impor- tant are intra-individual and inter-individual variance in flower characters? Are there microgeographical differences in flower characters? And if so, are they consistent between years? In 2008 and 2009, we sampled flowers of 72 trees from five localities. For six flower morphological and two nectar characteristics, we calculated coefficients of varia- tion (CV). The partitioning of total variation among- localities, among-individuals, and within-individuals was estimated. To analyze differences among localities and their consistency between years, we conducted generalized linear mixed models. The CVs of nectar characters were always higher than those of morphological characters. As expected, inter-individual variation was the main source of variation of flower morphology, but nectar characters had significant variation at both intra- and inter-individual levels. For most floral traits, there were no differences among localities. Our study documents that variation is a scale-dependent phenomenon and that it is essential to consider intra- and inter-individual variance when investi- gating the causes and consequences of variation. It also shows that single year studies of floral characters should be viewed with caution.

Two new aromatic glycosides, benzyl beta-D-glucopyranosyl-(1-->2)-[beta-D-apiofuranosyl-(1-->6)]-beta- D- glucopyranoside and p-[beta-D-apiofuranosyl-(1-->6)]-beta-D- glucopyranosyloxy-benzylic alcohol, have been isolated from the aerial parts of Pyrus bourgaeana (Rosaceae). The structures were elucidated by spectral analyses (including 2D-NMR spectral measurements) and chemical methods. Arbutin and four other aromatic glycosides have also been isolated and identified.

A new flavonol glycoside, isorhamnetin 5-O-β- d -galactopyranoside, was isolated from the aerial parts of Pyrus bourgaeana. The known compounds isorhamnetin 3-galactoside, 3-rutinoside, 3-glucoside, 3-rhamnoside and quercetin 3-rutinoside were also identified in the plant. The structures of the compounds were determined with spectroscopic methods including 2D NMR techniques.