Drivers of the structure of plant–hummingbird interaction networks at multiple temporal scales

Abstract

In semi-arid environments, the marked contrast in temperature and precipitation over the year strongly shapes ecological communities. The composition of species and their ecological interactions within a community may vary greatly over time. Although intra-annual variations are often studied, empirical information on how plant-bird relationships are structured within and among years, and how their drivers may change over time are still limited. In this study, we analyzed the temporal dynamics of the structure of plant-hummingbird interaction networks by evaluating changes in species richness, diversity of interactions, modularity, network specialization, nestedness, and β-diversity of interactions throughout four years in a Mexican xeric shrubland landscape. We also evaluated if the relative importance of abundance, phenology, morphology, and nectar sugar content consistently explains the frequency of pairwise interactions between plants and hummingbirds across different years. We found that species richness, diversity of interactions, nestedness, and network specialization did vary within and among years. We also observed that the β-diversity of interactions was high among years and was mostly associated with species turnover (i.e., changes in species composition), with a minor contribution of interaction rewiring (i.e., shifting partner species at different times). Finally, the temporal co-occurrence of hummingbird and plant species among months was the best predictor of the frequency of pairwise interactions, and this pattern was consistent within and among years. Our study underscores the importance of considering the temporal scale to understand how changes in species phenologies, and the resulting temporal co-occurrences influence the structure of interaction networks.

Seeing through the static: the temporal dimension of plant–animal mutualistic interactions

“…In any ecosystem, once the condition of phenological overlap is met, morphological traits, variation in species abundances, and species interaction flexibility can all come in as important determinants of which interactions form (Kaiser‐Bunbury et al ., 2014; Simanonok and Burkle, 2014; CaraDonna et al ., 2017). The relative importance of these factors will likely depend on their relative magnitude of variation, as factors with greater variation are arguably more likely to be important determinants of the occurrence of interactions and their functioning (Vázquez et al ., 2005; CaraDonna et al ., 2017; Chávez‐González et al ., 2020).…”

Heterogeneidad espacial a pequeña escala y diversidad de interacciones planta-visitante floral en alta montaña

“…En segundo lugar, estudios futuros que combinen información sobre compatibilidad de rasgos y abundancias relativas de plantas pueden mejorar la comprensión de los mecanismos que determinan la ocurrencia y frecuencia espaciales de las interacciones (Dupont et al 2014;Poisot et al 2015). En tercer lugar, la materialización de las interacciones varía mucho no solo espacialmente sino también temporalmente (Alarcón et al 2008;Burkle et al 2013;Chávez-González et al 2020). Por tanto, algunas interacciones ausentes pueden deberse a variaciones temporales en las interacciones de polinización (Kaiser-Bunbury et al 2010;Montero-Castaño y Vilà 2017;Vizentin-Bugoni et al 2020), cuya inclusión probablemente reduciría el número de interacciones únicas y, en consecuencia, la pérdida de interacciones predicha.…”

Phylogenetic structure of specialization: A new approach that integrates partner availability and phylogenetic diversity to quantify biotic specialization in ecological networks

“…For example, a pollination interaction between a hummingbird and a flowering plant may depend both on their morphological trait matching (e.g., flower corolla length and hummingbird bill length) and on the probability that the hummingbird will encounter the flower while foraging (Peralta et al, 2020 ; Sonne et al, 2020 ; Young et al, 2021 ). Multiple studies have quantified the relative importance of these two types of processes at the community level (Canard et al, 2014 ; Chávez‐González et al, 2020 ; Maglianesi et al, 2014 ; Simmons et al, 2019 ; Sonne et al, 2020 ; Stang et al, 2007 ; Vizentin‐Bugoni et al, 2014 ). As expected (Vázquez et al, 2009 ), traits that mediate species interactions often have predictive power for interactions and interaction frequencies (Maglianesi et al, 2014 ; Sonne et al, 2020 ; Vizentin‐Bugoni et al, 2014 ).…”

“…As expected (Vázquez et al, 2009 ), traits that mediate species interactions often have predictive power for interactions and interaction frequencies (Maglianesi et al, 2014 ; Sonne et al, 2020 ; Vizentin‐Bugoni et al, 2014 ). However, in multiple cases, partner availability has been found to have a more important role in explaining species interactions (Canard et al, 2014 ; Chávez‐González et al, 2020 ; Simmons et al, 2019 ; Stang et al, 2007 ).…”

“…The growing evidence that ecological interactions of many species are driven, at least at some scales, by the availability of potential partners (Canard et al, 2014 ; Chávez‐González et al, 2020 ; Simmons et al, 2019 ; Stang et al, 2007 ), calls for approaches to measure specialization that appropriately incorporate partner availability. We developed an index, phylogenetic structure of specialization (PSS), that integrates partner availability and phylogenetic diversity to measure biotic specialization in ecological networks.…”