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  • 1
    Electronic Resource
    Electronic Resource
    Pollination of Euphorbia dendroides by lizards and insects: Spatio-temporal variation in patterns of flower visitation (1997)
    Springer
    Oecologia 111 (1997), S. 241-248 
    Details
    ISSN: 1432-1939
    Keywords: Key words Lizard pollination ; Insect pollination ; Euphorbia dendroides ; Podarcis lilfordi ; Balearic Islands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The patterns of flower visitation by lizards (Podarcis lilfordi, Lacertidae) and insects (mainly flies, bees and wasps) on the shrub Euphorbia dendroides, were studied in the island of Cabrera (Balearic Islands) during the flowering seasons of 1995 and 1996. Lizards act as true pollinators of the plant, moving large quantities of pollen within and among shrubs. To our knowledge, this is the first time that pollination by lizards has been empirically demonstrated. Variation in the quantitative component of pollination (frequency of visits × flower visitation rate) by the two groups of pollinators (lizards and insects) is documented at both spatial (within a plant population) and temporal scales (throughout the flowering season and between seasons). Variation in lizard density on a small spatial scale (within c. 200 m), presumably due to differences in vegetation cover, strongly affected their frequency of flower visitation. Insects were rather scarce, mainly because the plant flowers at a time (mid-March) when temperatures are still low. At the site where lizards were abundant, their frequency of flower visits was more than 3 times that of insects, they stayed on the shrubs about 3 times longer and visited about 8 times more cyathia per minute than did insects. Fruit and seed set were greater at this site, and this is attributed to the different frequency of flower visits by lizards, as shrubs are similar in size and produce similar amounts of cyathia in the two sites compared. Both, lizards and insects went more frequently to plants with large flower crops. However, flower crop was not associated with seed viability. We found no evidence for pollinator-mediated selection on plant traits related to fitness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008816
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  • 2
    Electronic Resource
    Electronic Resource
    Spatio-temporal variation in pre-dispersal reproductive losses of a Mediterranean shrub, Euphorbia dendroides L. (1995)
    Springer
    Oecologia 103 (1995), S. 118-126 
    Details
    ISSN: 1432-1939
    Keywords: Reproductive success ; Insect herbivory ; Seed predation ; Euphorbiaceae ; Balearic Islands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The factors that reduce the pre-dispersal reproductive potential of Euphorbia dendroides are identified and the magnitude and variability of their effects are examined, both on a spatial and on a temporal scale. The aims of the study were: (1) to assess whether such variation was related to plant attributes describing size and/or fecundity, and (2) to determine the consistency of those effects in plant reproductive success. Pre-dispersal losses were measured over 3 years in a total of 45 plants from two populations in Cabrera island (Balearic Islands, western Mediterranean). Two types of insect-plant interactions (a moth that preys on the inflorescences and a wasp that feeds on the seeds) significantly reduced the potential number of seeds of E. dendroides, whereas lack of ovary in the cyathium, ovary abortion or seed abortion were the causes of reproductive loss that can be considered “intrinsic” to the plant. Significant variation was found both spatially and temporally in their effects, though such variation could not be attributed to the plant traits measured. Moths and wasps were not found to exert any opposing selective pressure on the plant, and their effect was additive. Key factor analyses performed with the data obtained over three seasons showed that the influence of a factor on among-plant variation in total reproductive losses cannot be predicted by the magnitude of the loss caused by such a factor; thus, seed abortion, while representing a low reproductive loss (〈 20% of the potential seed production) accounted for the greatest among-plant variation in total losses. The analyses also showed that the contribution of the plant-insect interactions to the variation in total losses varied significantly both spatially and temporally. This lack of consistency, together with the lack of association with the plant traits measured, suggests that the demographic changes produced by these interactions are unlikely to translate into adaptive changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328432
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  • 3
    Electronic Resource
    Electronic Resource
    Pre-dispersal seed predation in Central AmericanAcacia farnesiana: factors affecting the abundance of co-occurring bruchid beetles (1991)
    Springer
    Oecologia 87 (1991), S. 570-576 
    Details
    ISSN: 1432-1939
    Keywords: Acacia farnesiana ; Bruchidae ; Pre-dispersal seed predation ; Insect-plant interactions ; Insect cooccurrence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pre-dispersal seed predation of the leguminousAcacia farnesiana byMimosestes nubigens andM. mimosae (Coleoptera: Bruchidae) was investigated in Santa Rosa National Park, northwestern Costa Rica. The purpose of the study was to determine the patterns of resource utilization by the seed predators and the mechanisms causing such patterns. Immature, mature, and fallen fruits were monitored during the dry seasons of 1987 and 1988 from different shrubs and areas. Parameters describing plant size, fecundity, and relative plant isolation were measured on each shrub. No evidence of spatial or temporal segregation was found between the two species and the intensity of seed predation was independent of the variables measured from each plant.M. mimosae was scarcer and always occurred withM. nubigens. Both were present in areas with low and high densities of the host plant, and the frequency distributions of their emergences from the fruits overlapped through the fruiting season.urosigalphus sp., a hymenopteran parasitoid, represented ca. 40% of all insect emergences in 1987 and ca. 30% in 1988. This wasp attacked a greater proportion of bruchid eggs on pods on the shrub than on pods beneath it, and more on green than on mature fruits. Parasitism thus appears to select against bruchid females that oviposit at an early stage of pod maturation. The harsh conditions of the dry season, namely heat and desiccation, also accounted for a high level of bruchid pre-emergence mortality, especially in fallen fruits, where survival from egg to adult was only about 18%. Beneath the shrubs, bruchid females exhibited selectivity, ovipositing more on pods in the shade than on those exposed to direct sunlight. In contrast to parasitoids, abiotic factors probably impose a selective force against those bruchid females that oviposit at a late stage of maturation or on pods already dropped. Both bruchid species can have more than one generation during the fruiting period. The intensity of seed predation did not, however, change during the season. The data obtained in this study suggest that factors like natural enemies and severe weather are more likely to limit the bruchid population densities than intra- or interspecific competition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320422
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of Agonoscena targionii (Licht.) (Homoptera: Psylloidea) on seed production by Pistacia terebinthus L. (1994)
    Springer
    Oecologia 98 (1994), S. 72-75 
    Details
    ISSN: 1432-1939
    Keywords: Insect herbivory ; Sap-feeding insects Psyllidae ; Anacardiaceae ; Southeastern Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study investigated the potential negative effect that psyllids may have on the production of viable seeds in Pistacia terebinthus, a wild plant species with a circummediterranean distribution. Manipulative experiments, involving the application of insecticide, showed that the reduction in fruit maturation is rather low, not exceeding 10%. This is mainly due to other factors that determine seed inviability. Such factors include those intrinsic to the plant, such as parthenocarpy and seed abortion, and extrinsic to it, such as seed predation by chalcidoid wasps. There is much variation in the frequency of psyllids per plant; such variation appears uncorrelated with variables decribing plant size, fecundity, and distance to fruiting conspecifics. No consistency in the incidence of psyllids on a given individual plant was found between years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00326092
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  • 5
    Electronic Resource
    Electronic Resource
    Post-dispersal predation of Acacia farnesiana seeds by Stator vachelliae (Bruchidae) in Central America (1990)
    Springer
    Oecologia 84 (1990), S. 506-512 
    Details
    ISSN: 1432-1939
    Keywords: Acacia farnesiana ; Bruchid oviposition patterns ; Insect-plant interactions ; Post-dispersal seed predation ; Stator vachelliae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Post-dispersal seed predation by the bruchid beetle Stator vachelliae was investigated in Santa Rosa National Park, Costa Rica. This insect finds the seeds of the leguminous Acacia farnesiana in the feces of horses, deer, and ctenosaur lizards, the current major dispersers. Patterns of oviposition and pre-adult survival of beetles in the seeds were investigated in a series of experiments using fresh horse dung. S. vachelliae never minded into the dung balls, attacking only those seeds located on the surface. Fresh horse dung did not attract insects more readily than dry dung. The proportion of seeds attacked was not related to their density in a defecation, and was similar in three areas with different densities of the host plant. In a fourth area with no fruiting A. farnesiana shrubs all seeds survived insect predation. Bruchids attacked a greater proportion of seeds at 1 m than at 5 m from the edge of the shrub's crown. Seeds were mainly removed from horse dung by rodents with similar intensity in all areas and at both distances; this seed removal interfered with bruchid oviposition and probably with bruchid survival. S. vachelliae oviposited less frequently on seeds in dung fully exposed to sun. When oviposition on a dung pile was high, the distribution of eggs on the seeds was clumped, suggesting that some seeds were preferred to others. By the end of the dry season, bruchids stopped attacking the seeds. The results show that the fate of both seeds and bruchids is greatly influenced by the location and time of defecation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328167
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  • 6
    Electronic Resource
    Electronic Resource
    Deceptive fruits reduce seed predation by insects inPistacia terebinthus L. (Anacardiaceae) (1993)
    Springer
    Evolutionary ecology 7 (1993), S. 357-361 
    Details
    ISSN: 1573-8477
    Keywords: parthenocarpy ; insect seed predation ; chalcidoid wasps ; Pistacia terebinthus ; Anacardiaceae ; western Mediterranean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The production of seedless fruits (parthenocarpy) is not yet understood from an evolutionary viewpoint, even though it is taxonomically widespread. Here I present a case in which parthenocarpy reduces the incidence of seed predation by insects. At least the first generation of chalcidoid wasps that oviposit in the fruits ofPistacia terebinthus L. (Anacardiaceae) cannot discriminate among viable and inviable fruits, allocating energy and time to oviposition on fruits that are not suitable for larval development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237867
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  • 7
    Electronic Resource
    Electronic Resource
    Ecology of the fruit-colour polymorphism in Rubus spectabilis (1998)
    Springer
    Evolutionary ecology 12 (1998), S. 331-345 
    Details
    ISSN: 1573-8477
    Keywords: avian seed dispersal ; colour preferences ; fruit polymorphism ; seed germination ; southeast Alaska
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Although some studies have focused on the colour polymorphisms of flowers and fruits, little is known of their ecological and evolutionary significance. We investigated the potential contribution of several factors to the maintenance of fruit-colour polymorphism in Rubus spectabilis, a common shrub in the temperate rainforests of southeast Alaska. Fruits occur in two colours (red and orange), whose frequencies vary geographically. The two colour morphs have similar size, weight, seed load and nutrient composition. Colour preferences of avian frugivores, in the aviary and in the field, varied among individuals, but the majority favoured red fruits. Seed predators (mostly rodents) did not discriminate between seeds from different morphs. The effect of seed passage through the digestive tract of frugivores (birds and bears) on germination was similar for both morphs, although there were significant differences among frugivores. The type of soil on which the seeds are deposited influenced their germination behaviour, suggesting that some soils could favour one morph over the other. Such differences may contribute to the regional differences in frequencies of the two morphs. This study emphasizes the need to investigate fruit and seed characteristics that correlate with fruit colour; the colour preferences of consumers is only one of several selection pressures that determine the frequency distribution of fruit colours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006504317585
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  • 8
    Electronic Resource
    Electronic Resource
    Influence of type of avian frugivory on the fitness ofPistacia terebinthus L. (1994)
    Springer
    Evolutionary ecology 8 (1994), S. 618-627 
    Details
    ISSN: 1573-8477
    Keywords: seed dispersal ; avian frugivory ; plant—animal interactions ; Anacardiaceae ; southeastern Spain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fruits ofPistacia terebinthus, a circum-Mediterranean tree/shrub, are consumed by an array of bird species that differ in feeding methods and in relative frequencies of visits to plants. In this study I document interindividual variation in the proportion of fruits consumed by three types of frugivores: legitimate dispersers, pulp-consumers and seed predators. The results show that the relative frequencies of each kind of frugivore notably influence the final reproductive output (absolute number of viable seeds dispersed) and in fact prevail over the effects of pre-dispersal factors acting on plant fitness. Those relative frequencies are not associated with any of the plant traits related to fitness, such as fruit crop size and the number of viable seeds produced, suggesting that the type of avian frugivory exerts a negligible, if not null, selective pressure on such plant attributes. Plant specialization to attract the most effective seed dispersers seems to be precluded, given the small scale at which the high variation in seed dispersal success takes place.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237845
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  • 9
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    Integration of invasive Opuntia spp. by native and alien seed dispersers in the Mediterranean area and the Canary Islands (2010)
    Springer
    Details
    Publication Date: 2010-09-24
    Print ISSN: 1387-3547
    Electronic ISSN: 1573-1464
    Topics: Biology
    Published by Springer
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  • 10
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    Consistency in the habitat degree of invasion for three invasive plant species across Mediterranean islands (2009)
    Springer
    Details
    Publication Date: 2009-11-27
    Print ISSN: 1387-3547
    Electronic ISSN: 1573-1464
    Topics: Biology
    Published by Springer
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