Boris A. Tinoco

Parasites play important roles in ecological and evolutionary processes, yet host–parasite dynamics in high-elevation Neotropical ecosystems remain poorly understood. Specifically, we asked whether haemosporidian assemblages at extreme elevations are dominated by Leucocytozoon, whether infection patterns are phylogenetically and ecologically structured across avian hosts, and whether infections produce detectable physiological costs at the community level. We sampled 214 individuals representing 37 bird species across three Polylepis forest sites (~3700–4000 m a.s.l.) in northern Ecuador, and screened blood samples for Plasmodium, Haemoproteus, and Leucocytozoon. Overall infection prevalence was 39.7%, with Leucocytozoon accounting for 88.2% of infections. We identified 63 parasite lineages, including 40 previously undescribed lineages. Infection probability varied among host species, increased with body mass, and showed phylogenetic structure, with closely related host species tending to show similar infection probability. Host-specific analyses revealed non-random phylogenetic structure of parasite assemblages in several bird species. Quantitative host–parasite interaction networks showed low connectance, moderate specialization, and significant departures from null expectations, suggesting that only a limited subset of potential host–parasite associations is realized. Despite high prevalence and frequent coinfections, infection status was not associated with body condition, hemoglobin concentration, or hematocrit. Together, these results indicate that haemosporidian communities in high Andean Polylepis forests are highly diverse and exhibit pronounced non-random and phylogenetic structure in their host–parasite associations. The presence of numerous novel lineages further suggests that parasite diversity in tropical high-elevation ecosystems remains substantially underestimated.

Niche partitioning is often considered an important mechanism promoting species co‐occurrence in species‐rich communities. As species richness increases, niche partitioning may lead to different niche structures, including increased packing of species niches when the community niche space remains unchanged, or expansion of the community niche spaces as additional species are incorporated. In hummingbird assemblages, competitive interactions can strongly influence niche partitioning, and competition often is influenced by resource availability and bill morphology. However, it remains unclear whether resource availability and morphological traits influence hummingbird co‐occurrence through niche expansion or packing. Here, we used the interaction niche—which quantifies hummingbird resource niches in terms of plant traits on which the birds forage—to evaluate whether interaction niche packing or expansion characterizes hummingbird co‐occurrence in a high‐Andean montane forest in southern Ecuador. We found that when hummingbird species richness was high, interaction niche packing and not expansion predominated and was characterized by greater niche overlap among species. However, niche overlap was greater when flower resource availability was low and lower when co‐occurring hummingbirds had divergent bill lengths. These results highlight the importance of morphological traits and floral resource availability on interaction niche overlap in Andean hummingbird species, and how this, in turn, defines patterns of species co‐occurrence. Further, these findings reveal that the interaction niche offers a powerful tool to explore the ecological processes potentially leading to species co‐occurrence. Read the free Plain Language Summary for this article on the Journal blog.

Tropical forest recovery is triggered by seed dispersal provided by animal frugivores. Plant and animal traits shape the interactions between plants and frugivores, ultimately determining the functional diversity of seed rain. However, it remains poorly understood how the functional diversity and composition of plant–frugivore interactions and seed rain are affected by processes at both local and landscape scales. We investigated how local forest structure and landscape‐scale forest connectivity shape the functional recovery of seed rain mediated by plant–frugivore interactions. At 24 recovering forest and 8 old‐growth forest plots, we measured forest structure and connectivity, recorded plant–frugivore interactions and quantified seed rain in a total of 384 seed traps. Forest structure was quantified from vegetation heterogeneity, above‐ground biomass and tree height, and forest connectivity from surrounding forest cover and the distance to the closest forest. Using plant and frugivore traits, we quantified the functional recovery of plant–frugivore interactions and seed rain and applied structural equation models to test the direct and indirect effects of forest structure and connectivity on the functional diversity and composition of seeds. Forest structure primarily influenced seed rain functional diversity mediated by local plant–frugivore interactions. In addition, forest connectivity was the main driver of the functional composition of seed rain. Large seeds and seeds of late‐successional species were found more often in recovering forests with high connectivity, both through direct and indirect effects via plant–frugivore interactions. These patterns suggest two complementary mechanisms of forest recovery. Structurally complex forests support diverse plant and animal communities that foster a functionally diverse seed rain. Forest connectivity, in addition, promotes animal movement across the landscape, facilitating the dispersal of seeds from old‐growth forests into recovering forests. Synthesis. Local forest structure and landscape‐scale connectivity shape distinct but complementary aspects of the functional recovery of seed rain. These findings highlight that tropical forest restoration requires considering both local and landscape‐scale processes to ensure the recovery of functionally diverse tropical forests.

In pollination networks, indirect plant–plant interactions mediated by their shared pollinators can shape community dynamics and species fitness; yet, the influence of floral traits on species roles remains unclear, particularly in diverse ecosystems like the tropical Andes. We studied hummingbird‐mediated interactions among 31 flowering plants in three high‐elevation shrubby habitats located in southern Ecuador. During August and November 2022, and January 2023, we collected stigma samples and constructed weighted interaction networks linked by heterospecific pollen grains. Species roles were determined by defining if they were donors or receivers of pollen, measured by node degree out and node degree in, respectively. We also explored the association between the abundance of flowers and different floral traits and species roles. Finally, we assessed the potential influence of floral roles on species fitness by calculating the ratio of conspecific‐to‐heterospecific pollen grains observed in each species. We found that the identity of donor and receiver species was highly dynamic across habitats and time. Receiver species were characterized by being highly abundant, while donor species presented high levels of nectar production. Receiver species received more heterospecific pollen than conspecific pollen, indicating that the pollen‐sharing roles of species could have fitness consequences. Our findings highlight the importance of some floral traits and abundance in shaping floral roles and their potential fitness consequences in hummingbird‐mediated indirect interactions.

Plant species pollinated by animals differ in the pool of visitors they attract. Some attract functionally similar animals, while others engage with a broader set of functionally distinct visitors; we term this species‐level variation functional generalism. Here, we explore the influence of plant traits and context‐dependent factors on functional generalism, and the potential effects of this overlooked aspect of mutualistic interactions on species' reproductive outcomes. We quantified functional generalism in 211 hummingbird‐visited plant species across 32 sites in three regions of Costa Rica, Ecuador and Brazil. We related functional generalism to plant traits (corolla length, opening, curvature) and context‐dependent factors, including the abundance and flowering duration of the focal plant species, as well as the functional diversity of co‐flowering plant species and of hummingbird pools during its flowering period. Finally, we assessed how functional generalism influenced plant reproductive outcomes (visitation rate and proportion of nectar‐robbing visits). Species with long, narrow corollas had the highest functional generalism, attracting more functionally diverse hummingbirds. Functional generalism increased in functionally diverse plant communities, highlighting the influence of neighbours within the same trophic level. Abundant species with short flowering periods had greater functional generalism than less abundant, continuously flowering species. Functional generalism had a hump‐shaped relationship with visitation rate, peaking at moderate levels but declining afterward. Moreover, the proportion of nectar‐robbing visits increased with functional generalism. These findings reveal the joint influence of plant traits and community context on functional generalism, which in turn affects plants' reproductive success. Read the free Plain Language Summary for this article on the Journal blog.

In pollination networks, indirect plant-plant interactions mediated by their shared pollinators, can shape community dynamics and species fitness; yet, the influence of floral traits on species roles remains unclear, particularly in diverse ecosystems like the tropical Andes. We studied hummingbird-mediated interactions among 31 flowering plants in three high-elevation shrubby habitats located in southern Ecuador. During August and November 2022, and January 2023, we collected stigma samples and constructed weighted interaction networks linked by heterospecific pollen grains. Species roles were determined by defining if they were overall donors or receptors of pollen. We also explored the association between the abundance of flowers and different floral traits and species roles. Finally, we assessed the potential influence of floral roles on species fitness by calculating the ratio of conspecific-to-heterospecific pollen grains observed in each species. We found that the identity of donor and receptor species was highly dynamic across sites and time. Donor species were characterized by being highly abundant, and having long and wide corollas, while receptor species had low abundance, and short and narrow corollas. Donor species received less heterospecific pollen than conspecific pollen, indicating that the pollen sharing roles of species could have fitness consequences. Our findings highlight the importance of floral traits and abundance in shaping floral roles and their potential fitness consequences in hummingbird-mediated indirect interactions.

Functional traits determine interactions between plants and pollinators, and to increase pollination efficiency, many plants have evolved traits to attract specific pollinator groups. However, biogeographical setting may influence trait evolution and biotic interactions. For instance, plants pollinated by hummingbirds often have ornithophilous traits, that is, flowers with elongated corollas, dilute nectar and red colours, but—due to colonization history, depauperate biotas and unstable environmental conditions—it might be disadvantageous for species to rely on mutualistic partners with specific functional traits on oceanic islands. Hummingbird‐visited plants on islands are thus expected to have fewer ornithophilous traits and be functionally less diverse in their interactions with hummingbirds. We compiled an extensive dataset of plant—hummingbird interactions (1030 plant and 181 hummingbird species) and associated functional traits. We divided the data into four biogeographical regions across the American mainland and the Caribbean islands and then tested whether biogeographical regions differed in the proportion of ornithophilous floral traits and functional diversity of plant—hummingbird interactions. We found that hummingbird‐visited plant communities of the Caribbean islands displayed the lowest proportion of traits typically associated with a functional adaptation towards bird‐mediated pollination, with on average the shortest corollas, the highest nectar concentrations and the largest proportion of non‐ornithophilous colours. Contrary to our expectations, plants in the Caribbean interacted with hummingbirds that were morphologically more distinct than the plants of mainland regions. Overall, we document a strong imprint of insularity on floral traits and interactions with hummingbirds. While hummingbird‐visited plants in the Caribbean displayed floral traits that support island theory, predicting less specific pollination systems on oceanic islands, the functional diversity of plant–hummingbird interactions in the Caribbean communities was higher than on the mainland, possibly driven by competition over resources. These results highlight the influence of insularity on functional traits and plant–pollinator interactions. Read the free Plain Language Summary for this article on the Journal blog.

Interactions between plants and animals are crucial for natural forest recovery because most plants rely on seed dispersal by animals to recolonize degraded habitats. Despite this importance, the recovery time of seed-dispersal interactions after deforestation is unknown. We compared the recovery time of the functional diversity of seed-dispersal interactions, frugivorous animals and fleshy-fruited plants by recording trait and interaction data along a chronosequence of tropical forest recovery. Using a Bayesian model, we estimated that plant functional diversity was high shortly after deforestation, but animal functional diversity recovered only after 39 years, and seed-dispersal interactions after 18 years. We demonstrate that seed-dispersal interactions need about two decades to functionally recover which provides a new benchmark for the timing of restoration projects in tropical forests.

In pollination networks, indirect plant-plant interactions mediated by their shared pollinators, can shape community dynamics and species fitness; yet, the influence of floral traits on species roles remains unclear, particularly in diverse ecosystems like the tropical Andes. We studied hummingbird-mediated interactions among 31 flowering plants in three high-elevation shrubby habitats located in southern Ecuador. During August and November 2022, and January 2023, we collected stigma samples and constructed weighted interaction networks linked by heterospecific pollen grains. Species roles were determined by defining if they were overall donors or receptors of pollen. We also explored the association between the abundance of flowers and different floral traits and species roles. Finally, we assessed the potential influence of floral roles on species fitness by calculating the ratio of conspecific-to-heterospecific pollen grains observed in each species. We found that the identity of donor and receptor species was highly dynamic across sites and time. Donor species were characterized by being highly abundant, and having long and wide corollas, while receptor species had low abundance, and short and narrow corollas. Donor species received less heterospecific pollen than conspecific pollen, indicating that the pollen sharing roles of species could have fitness consequences. Our findings highlight the importance of floral traits and abundance in shaping floral roles and their potential fitness consequences in hummingbird-mediated indirect interactions.