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Projeto de investigação
Old-field recolonization by animal-dispersed keystone plants: combining field work, genetics and individual-based modelling.
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Spatial isolation impacts pollinator visitation and reproductive success of a threatened self-incompatible Mediterranean tree
Publication . Alonso-López, M.Teresa; Garrote, Pedro J.; Fedriani, José M.
Pollination service is crucial to achieve successful plant sexual reproduction and long-term population persistence.
This pollination service can be affected by plant conspecific density and also by intrinsic features of individuals
related to their flowering phenology and floral display. However, studies examining intrinsic and
extrinsic traits on pollinator visitation and reproductive success of Mediterranean trees with limited reproduction
are still scarce. We analyzed the effects of plant isolation, flowering phenology, flower weight and tree size on
flower visitation probability, flowering patch visitation probability, fruit set and crop size. To this end, we
intensively monitored pollinator visitation and fruit production of 67 (in 2019) and 73 (in 2020) Pyrus bourgaeana
Decne trees within a threatened Mediterranean population. Our results revealed that isolated individuals
received more pollinators than those on conspecific aggregations, suggesting intraspecific competition for pollinators
in dense flowering neighborhoods. However, fruit set was higher in trees close to flowering conspecifics
despite having fewer visits from pollinators, suggesting pollen limitation but not pollinator limitation in spatially
isolated trees. Interestingly, we found increased crop sizes in spatially isolated trees which could be related to
reduced intraspecific competition for resources in low-density neighborhoods (water, nutrients) and/or to higher
reproductive investment (i.e. higher flower production). Overall, our results indicated pollen but not pollinator
limitation in spatially isolated trees. Under this scenario of sexual reproduction mediated by pollinators, our
findings stress the relevance of individuals’ spatial distribution for self-incompatible trees exhibiting low individuals’
densities
Examining the spatiotemporal variation of genetic diversity and genetic rarity in the natural plant recolonization of human-altered areas
Publication . Garrote, Pedro J.; Castilla, Antonio R.; Picó, F. Xavier; Fedriani, Jose M.
The spatiotemporal genetic variation at early plant life stages may substantially affect the natural recolonization of humanaltered
areas, which is crucial to understand plant and habitat conservation. In animal-dispersed plants, dispersers’ behavior
may critically drive the distribution of genetic variation. Here, we examine how genetic rarity is spatially and temporally
structured in seedlings of a keystone pioneer palm (Chamaerops humilis) and how the variation of genetic rarity could ultimately
affect plant recruitment. We intensively monitored the seed rain mediated by two medium-sized carnivores during
two consecutive seasons in a Mediterranean human-altered area. We genotyped 143 out of 309 detected seedlings using 12
microsatellite markers. We found that seedlings emerging from carnivore-dispersed seeds showed moderate to high levels
of genetic diversity and no evidence of inbreeding. We found inflated kinship among seedlings that emerged from seeds
within a single carnivore fecal sample, but a dilution of such FSGS at larger spatial scales (e.g. latrine). Seedlings showed a
significant genetic sub-structure and the sibling relationships varied depending on the spatial scale. Rare genotypes arrived
slightly later throughout the dispersal season and tended to be spatially isolated. However, genetic rarity was not a significant
predictor by itself which indicates that, at least, its influence on seedling survival was smaller than other spatiotemporal
factors. Our results suggest strong C. humilis resilience to genetic bottlenecks due to human disturbances. We highlight the
study of plant-animal interactions from a genetic perspective since it provides crucial information for plant conservation and
the recovery of genetic plant resilience.
Old-field recolonization by animal - dispersed keystoneplants: combining field work, genetics and apatially-explicit modelling
Publication . Garrote García, Pedro José; Laffitte, José María Fedriani; Castilla Álvarez, Antonio Ramón; Bugalho, Miguel Nuno do Sacramento Monteiro
The transformation and destruction of natural areas for their exploitation as agricultural lands is a typical example of land-use change that generates high ecosystem degradation worldwide. However, during the last decades, many agricultural lands are being abandoned due to multiple socio-economic factors. Currently, there is a trend that sees the farmland abandonment as an opportunity to restore the functioning of these human-altered ecosystems. To take advantage of this opportunity, it is central to understand the ecological processes that drive and limit the natural regeneration of plant communities in these old-fields. This doctoral dissertation addresses the understanding of two central stages that determine the natural (re)colonization of old-fields where interspecific interactions are central: seed arrival and seedling recruitment and establishment. To do this, a multidisciplinary framework that combines intensive field work, molecular techniques and spatially explicit modelling was used in three old-fields located in southwestern Iberian Peninsula. Specifically, it was applied to the system comprised of the dwarf palm (Chamaerops humilis L.), a pioneer palm endemic to the Mediterranean, and its interspecific interactions with frugivorous mammals (ungulates and carnivores) and woody plant species. The results showed that carnivores promoted a considerable seed arrival. The fecal marking behavior of dispersers, especially badgers, impacted the spatial and genetic structure of dispersed seeds and seedlings. Several nurse shrub species were quantitatively compared, being identified the dwarf palm as a ‘keystone’ species. Indeed, for the first time, it was experimentally demonstrated the role of the dwarf palm as nurse plant of several woody species. However, the strong variation among individual palms confirmed the presence of the facilitation-competition continuum and therefore, that these plant-plant interactions are not always positive. Besides, spatial evidences of the role of the dwarf palm as ‘perche’ for frugivorous birds were found. In conclusion, using the system ‘dwarf palm-mammals-woody plants’ as a model, it was revealed how the natural (re)colonization of old-fields can promote their self-recovery, although active restoration interventions can be highly recommendable to increase the regeneration of some plant communities.
Interspecific interactions among functionally diverse frugivores and their outcomes for plant reproduction: a new approach based on camera-trap data and tailored null models
Publication . Selwyn, Miriam; Garrote, Pedro J.; Castilla, Antonio R.; Fedriani, Jose M.
The study of plant-frugivore interactions is essential to understand the ecology and evolution
of many plant communities. However, very little is known about how interactions among frugivores
indirectly affect plant reproductive success. In this study, we examined direct interactions
among vertebrate frugivores sharing the same fruit resources. Then, we inferred
how the revealed direct interspecific interactions could lead to indirect (positive or negative)
effects on reproductive success of fleshy fruited plants. To do so, we developed a new analytical
approach that combines camera trap data (spatial location, visitor species, date and
time, activity) and tailored null models that allowed us to infer spatial-temporal interactions
(attraction, avoidance or indifference) between pairs of frugivore species. To illustrate our
approach, we chose to study the system composed by the Mediterranean dwarf palm, Chamaerops
humilis, the Iberian pear tree, Pyrus bourgaeana, and their shared functionally
diverse assemblages of vertebrate frugivores in a Mediterranean area of SW Spain. We first
assessed the extent to which different pairs of frugivore species tend to visit the same or different
fruiting individual plants. Then, for pairs of species that used the same individual
plants, we evaluated their spatial-temporal relationship. Our first step showed, for instance,
that some prey frugivore species (e.g. lagomorphs) tend to avoid those C. humilis individuals
that were most visited by their predators (e.g. red foxes). Also, the second step revealed
temporal attraction between large wild and domestic frugivore ungulates (e.g. red deer,
cows) and medium-sized frugivores (e.g. red foxes) suggesting that large mammals could
facilitate the C. humilis and P. bourgaeana exploitation to other smaller frugivores by making
fruits more easily accessible. Finally, our results allowed us to identify direct interaction pathways,
that revealed how the mutualistic and antagonistic relations between animal associates
derived into indirect effects on both plants seed dispersal success. For instance, we
found that large-sized seed predators (e.g. ungulates) had a direct positive effect on the likelihood
of visits by legitimate seed dispersers (e.g. red foxes) to both fleshy fruited plants.
Then, seed predators showed an indirect positive effect on the plants’ reproductive Our new analytical approach provides a widely applicable framework for further studies on
multispecies interactions in different systems beyond plant-frugivore interactions, including
plant-pollinator interactions, the exploitation of plants by herbivores, and the use of carcasses
by vertebrate scavengers
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
SFRH/BD/130527/2017