What is long-distance dispersal? And a taxonomy of dispersal events

Dispersal is a key individual-based process influencing many life-history attributes and scaling up to population-level properties (e.g. metapopulation connectivity). A persistent challenge in dispersal ecology has been the robust characterization of dispersal functions (kernels), a fundamental tool to predict how dispersal processes respond under global change scenarios. Particularly, the rightmost tail of these functions, that is the long-distance dispersal (LDD) events, are difficult to characterize empirically and to model in realistic ways. But, when is it a LDD event? In the specific case of plants, dispersal has three basic components: (i) a distinct (sessile) source, the maternal plant producing the fruits or the paternal tree acting as a source of pollen; (ii) a distance component between source and target locations; and (iii) a vector actually performing the movement entailing the dispersal event. Here, I discuss operative definitions of LDD based on their intrinsic properties: (i) events crossing geographic boundaries among stands; and (ii) events contributing to effective gene flow and propagule migration. Strict-sense long-distance dispersal involves movement both outside the stand geographic limits and outside the genetic neighbourhood area of individuals. Combinations of propagule movements within/outside these two spatial reference frames result in four distinct modes of LDD. Synthesis. I expect truncation of seed dispersal kernels to have multiple consequences on demography and genetics, following to the loss of key dispersal services in natural populations. Irrespective of neighbourhood sizes, loss of LDD events may result in more structured and less cohesive genetic pools, with increased isolation by distance extending over broader areas. Proper characterization of the LDD events helps to assess, for example, how the ongoing defaunation of large-bodied frugivores pervasively entails the loss of crucial LDD functions.Peer Reviewe

Relaciones interespecificas y coexistencia entre el Águila Real (Aquila chrysaetos) y el Águila Perdicera (Hieraaetus fasciatus) en sierra Morena central

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Curso Latino Americano de Frugivoria e Dispersão de Sementes

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Geographic patterns in plant-pollinator mutualistic networks

. Recent reviews of plant–pollinator mutualistic networks showed that gen- eralization is a common pattern in this type of interaction. Here we examine the ecological correlates of generalization patterns in plant–pollinator networks, especially how interaction patterns covar y with latitude, elevation, and insularity. We review the few published anal- yses of whole networks and include unpublished material, analyzing 29 complete plant– pollinator networks that encompass arctic, alpine, temperate, Mediterranean, and subtrop- ical–tropical areas. The number of interactions obser ved (I) was a linear function of network size (M ) the maximum number of interactions: ln I = 0.575 + 0.61 ln M; R2 = 0.946. The connectance (C), the fraction of obser ved interactions relative to the total possible, decreased exponentially with species richness, the sum of animal and plant species in each community (A + P): C = 13.83 exp[—0.003(A + P)]. After controlling for species richness, the residual connectance was significantly lower in highland (>1500 m elevation) than in lowland networks and differed marginally among biogeographic regions, with both alpine and trop- ical networks showing a trend for lower residual connectance. The two Mediterranean networks showed the highest residual connectance. After correcting for variation in network size, plant species were shown to be more generalized at higher latitude and lowland habitats, but showed increased specialization on islands. Oceanic island networks showed an im- poverishment of potential animal pollinators (lower ratio of animal to plant species, A : P, compared to mainland networks) associated with this trend of increased specialization. Plants, but not their flower-visiting animals, supported the often-repeated statements about higher specificity in the tropics than at higher latitudes. The pattern of interaction build- up as diversity increases in pollination networks does not differ appreciably from other mutualisms, such as plant–seed disperser networks or more complex food webs.Peer reviewe

Response to Comment on ‘‘Asymmetric Coevolutionary Networks Facilitate Biodiversity Maintenance’’

Mutualistic networks are characterized by weak and asymmetric interactions, which a simple model predicts will facilitate species coexistence. Holland et al. propose a more complex model and argue that coexistence is independent of mutualism strength. However, we show that mutualism strength still plays an important role in their model and that it significantly decreases with species richness as predicted.Peer reviewe

Coevolution and the architecture of mutualistic networks

Although coevolution is widely recognized as an important evolutionary process for pairs of reciprocally specialized species, its importance within species-rich communities of generalized species has been questioned. Here we develop and analyze mathematical models of mutualistic communities, such as those between plants and pollinators or plants and seed-dispersers to evaluate the importance of coevolutionary selection within complex communities. Our analyses reveal that coevolutionary selection can drive significant changes in trait distributions with important consequences for the network structure of mutualistic communities. One such consequence is greater connectance caused by an almost invariable increase in the rate of mutualistic interaction within the community. Another important consequence is altered patterns of nestedness. Specifically, interactions mediated by a mechanism of phenotype matching tend to be antinested when coevolutionary selection is weak and even more strongly antinested as increasing coevolutionary selection favors the emergence of reciprocal specialization. In contrast, interactions mediated by a mechanism of phenotype differences tend to be nested when coevolutionary selection is weak, but less nested as increasing coevolutionary selection favors greater levels of generalization in both plants and animals. Taken together, our results show that coevolutionary selection can be an important force within mutualistic communities, driving changes in trait distributions, interaction rates, and even network structure. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.Peer Reviewe

Downsized mutualisms: Consequences of seed dispersers' body-size reduction for early plant recruitment

© 2014 Geobotanisches Institut ETH, Stiftung Ruebel. Extinction-driven, body-size reduction of seed dispersers (i.e. an ecological downsizing resulting from severe defaunation) can entail the loss of unique ecological functions, and impair plant regeneration. However, the manner in which the downsizing of mutualistic animals affects seed dispersal and plant recruitment remains understudied. Here, we took advantage of a natural experiment in the Canarian archipelago to document the consequences of lizards body-size reduction (. Gallotia, Lacertidae) on the recruitment of Neochamaelea pulverulenta (Rutaceae), which relies exclusively on these frugivores for seed dispersal. Subsequent to the arrival of humans (ca. 2000-2500 yr BP), the extinction of large-bodied lizards generated a gradient of increasing defaunation on the three islands inhabited by this plant. We hypothesized a significant reduction, and eventually collapse, of early seedling recruitment mirroring the defaunation intensity of the frugivores. We sampled 42 populations spanning the whole geographic range of the plant to examine the quantitative (age structure pattern) and qualitative components (proportion of seedlings growing outside the canopy, number of seedlings established outside the canopy relative to the number of adults - effective recruitment rate, and seedling vigour) of plant regeneration. Our results show that the age structure patterns did not differ among the three contrasted insular scenarios. However, we found significant reductions in seedling recruitment outside the canopy, effective recruitment rate, and delayed negative effects on seedling vigour in populations hosting small- to medium-sized lizard species. Thus, extirpation of large seed-dispersers did not cause substantial reductions in quantitative components of seed dispersal, but determined declines in qualitative aspects impairing dispersal effectiveness. Our study highlights the importance of examining all components of the dispersal and recruitment process to properly document the regeneration outcomes of plants in defaunated, downsized ecological scenarios.Peer Reviewe

The temporal dynamics of resource use by frugivorous birds: a network approach

Ecological network patterns are influenced by diverse processes that operate at different temporal rates. Here we analyzed whether the coupled effect of local abundance variation, seasonally phenotypic plastic responses, and species evolutionary adaptations might act in concert to shape network patterns. We studied the temporal variation in three interaction properties of bird species (number of interactions per species, interaction strength, and interaction asymmetry) in a temporal sequence of 28 plant frugivore interaction networks spanning two years in a Mediterranean shrubland community. Three main hypotheses dealing with the temporal variation of network properties were tested, examining the effects of abundance, switching behavior between alternative food resources, and morphological traits in determining consumer interaction patterns. Our results demonstrate that temporal variation in consumer interaction patterns is explained by short-term variation in resource and bird abundances and seasonal dietary switches between alternative resources (fleshy fruits and insects). Moreover, differences in beak morphology are associated with differences in switching behavior between resources, suggesting an important role of foraging adaptations in determining network patterns. We argue that beak shape adaptations might determine generalist and specialist feeding behaviors and thus the positions of consumer species within the network. Finally, we provide a preliminary framework to interpret phylogenetic signal in plant animal networks. Indeed, we show that the strength of the phylogenetic signal in networks depends on the relative importance of abundance, behavioral, and morphological variables. We show that these variables strongly differ in their phylogenetic signal. Consequently, we suggest that moderate and significant phylogenetic effects should be commonly observed in networks of species interactions. Read More: http://www.esajournals.org/doi/abs/10.1890/07-1939.

Adaptation of flower and fruit colours to multiple, distinct 1 mutualists

Communication in plant–animal mutualisms frequently involves multiple perceivers. A fundamental uncertainty is whether and how species adapt to communicate with groups of mutualists having distinct sensory abilities. We quantified the colour conspicuousness of flowers and fruits originating from one European and two South American plant communities, using visual models of pollinators (bee and fly) and seed dispersers (bird, primate and marten). We show that flowers are more conspicuous than fruits to pollinators, and the reverse to seed dispersers. In addition, flowers are more conspicuous to pollinators than to seed dispersers and the reverse for fruits. Thus, despite marked differences in the visual systems of mutualists, flower and fruit colours have evolved to attract multiple, distinct mutualists but not unintended perceivers. We show that this adaptation is facilitated by a limited correlation between flower and fruit colours, and by the fact that colour signals as coded at the photoreceptor level are more similar within than between functional groups (pollinators and seed dispersers). Overall, these results provide the first quantitative demonstration that flower and fruit colours are adaptations allowing plants to communicate simultaneously with distinct groups of mutualists.Peer reviewe

Isolation of 91 polymorphic microsatellite loci in the western mediterranean endemic carex helodes (Cyperaceae)

Premise of the study: Microsatellite primers were developed for Carex helodes (Cyperaceae), a western Mediterranean endemic that is locally distributed in southern Portugal and southwestern Spain and rare in northern Morocco. Methods and Results: One hundred nine nuclear microsatellite markers were developed using a shotgun pyrosequencing method, resulting in 91 polymorphic and 18 monomorphic loci when tested using 19 individuals sampled from five populations from Portugal, Spain, and Morocco. Loci averaged 3.23 alleles per locus (SD = 1.15). In a single population (Cortelha population, Portugal), the 34 most polymorphic loci showed a mean observed heterozygosity of 0.357 (SD = 0.292) and mean expected heterozygosity of 0.384 (SD = 0.255). Conclusions: Next-generation sequencing allowed us to develop a high number of genetic markers with levels of polymorphism adequate to study gene flow among populations. However, when genotyping the individuals within a population, we found low levels of variation