Soil nutrient availability directly enhances vegetative growth, flowering, and fruiting in alpine ecosystems. However, the impacts of nutrient addition on pollinator visitation, which could affect seed output indirectly, are unknown. In a nutrient addition experiment, we tested the hypothesis that seed output in the insect-pollinated, self-incompatible shrub, Chuquiraga oppositifolia (Asteraceae) of the Andes of central Chile, is enhanced by soil nitrogen (N) availability. We aimed to monitor total shrub floral display, size of flower heads (capitula), pollinator visitation patterns, and seed output during three growing seasons on control and N addition shrubs. N addition did not augment floral display, size of capitula, pollinator visitation, or seed output during the first growing season. Seed mass and viability were 25-40% lower in fertilised shrubs. During the second growing season only 33% of the N addition shrubs flowered compared to 71% of controls, and a significant (50%) enhancement in vegetative growth occurred in fertilised shrubs. During the third growing season, floral display in N addition shrubs was more than double that of controls, received more than twice the number of insect pollinator visits, and seed output was three- to four-fold higher compared to controls. A significant (50%) enhancement in vegetative growth again occurred in N addition shrubs. Results of this study strongly suggest that soil N availability produces strong positive bottom-up effects on the reproductive output of the alpine shrub C. oppositifolia. Despite taking considerably longer to be manifest in comparison to the previously reported top-down indirect negative effects of lizard predators in the same study system, our results suggest that both bottom-up and top-down forces are important in controlling the reproductive output of an alpine shrub.

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The maintenance of flower size variation within populations might be explained by conflicting selection pressures on floral traits that may involve biological agents, such as mutualists and antagonists, and allocation costs associated with floral display. The annual species Madia sativa (Asteraceae) exhibits ample variation in the number of ray florets in natural populations. This field study aimed at evaluating the costs and benefits associated with floral traits in M. sativa. In particular, we addressed two main questions: (1) Is the number of ray florets positively associated with pollinator visitation rate? (2) Is there a fitness cost of ray floret maintenance when pollinators are absent? We detected one benefit of conspicuous ray capitula: a strong preference by insect pollinators. We also confirmed the occurrence of costs: when pollinators were excluded conspicuous ray capitula had a reduced reproductive assurance via autogamous selfing, and there were trade-offs between the number of ray florets and seed mass and seed germination. Results suggest that the maintenance of within-population variation in the number of ray florets in M. sativa is explained, at least in part, by the balance between costs and benefits associated with this floral trait.

13The introduction of carnivorous mammals has led many native island species to 14 extinction. In the Balearic Islands, the introduction of carnivorous mammals in the main 15 islands have contributed to the extinction of the endemic lizard Podarcis lilfordi, which 16 is an important seed disperser of many plant species. One of the introduced mammals, 17Martes martes (pine marten), is also known to disperse seeds and may replace the native 18 lizard in this role in islands. However, little is known on the patterns of seed dispersal 19 by these two different species and their possible implications for plant regeneration 20 ability and population structure. We have compared the quality of seed deposition 21 provided by both to the vulnerable Mediterranean shrub Cneorum tricoccon, by 22 studying the pattern of seed distribution among sites generated by both dispersers as 23 well as the suitability of those sites for seedling emergence and establishment. The 24 study was carried out in two types of habitats (coastal shrublands and pine forests) and 25 two islands (Mallorca and Dragonera). Lizards and mammals showed contrasting 26 patterns of seed deposition and, where lizards were absent, mammals played their role 27 as seed dispersers in pine forests but not in coastal shrublands. The lack of seed 28 dispersal in the coastal shrubland seriously limits recruitment, by concentrating seeds 29 under conspecifics and hindering colonization opportunities, marking a long-term trend 30 towards decline. The introduced predator replaces the native seed disperser in its service 31 where it has gone extinct, although with important differences in the dispersal service 32 provided.33 34

La mayoría de los reptiles, especialmente los lagartos, son insectívoros u omnívoros, razón por la cual poco se sabe acerca del rol que juegan como dispersores de plantas. Phymaturus flagellifer es una lagartija andina saxícola y herbívora. De acuerdo a observaciones preliminares sobre su comportamiento y a estimaciones de su ámbito de hogar, esta lagartija liberaría semillas lejos de la planta madre, y jugaría un rol como potencial dispersor. Este trabajo tiene por objetivo determinar si existe preferencia por el consumo de las distintas especies de semillas detectadas en las fecas y evaluar la legitimidad del lagarto como dispersor. Para esto, durante marzo del 2003, se recolectaron semillas de las plantas presentes en una área rocosa del Parque Nacional Laguna del Laja y en las fecas de P. flagellifer. Para estimar el efecto de la ingesta, se realizaron ensayos de germinación y pruebas de viabilidad. Para obtener una aproximación de la sombra de semilla producida por el lagarto, se midió el tamaño de ámbito de hogar del lagarto. Se obtuvo un total de 1.298 semillas, de 445 fecas analizadas, determinándose las semillas de tres especies de plantas: Berberis empetrifolia, Rumex acetosella y Calandrinia sp. Los resultados sugieren que no existe preferencia por el consumo de R acetosella y B. empetrifolia. En contraste, sí existe preferencia por consumir Calandrinia sp. Los ensayos de germinación y pruebas de viabilidad revelaron que el paso por el tracto digestivo de P. flagellifer afecta de manera diferencial a las semillas de las distintas especies de plantas. El porcentaje de germinación de R. acetosella fue significativamente mayor en el control, sin embargo la germinación B. empetrifolia y Calandrinia sp. no fue diferencial entre los tratamientos. El porcentaje de viabilidad de las semillas de B. empetrifolia provenientes del tracto digestivo fue significativamente mayor que aquél de semillas control. En cambio, las semillas de R. acetosella y Calandrinia sp., presentaron un porcentaje mayor de viabilidad en las semillas control. De acuerdo a estimaciones de ámbito de hogar, el área promedio en la cual P. flagellifer estaría alejando las semillas de la planta madre es de 20,75 ± 1,01 m 2. Los resultados obtenidos no permiten legitimar a P. flagellifer como dispersor de estas plantas. Esta especie podría movilizar las semillas que consume a nivel local e influir, también localmente y a largo plazo, la estructura y diversidad de la flora presente en el área.