Forest cover and connectivity have pervasive effects on the maintenance of evolutionary distinct interactions in seed dispersal networks

Abstract

Seed dispersal by animals is one of the most important ecological processes in tropical forests, entailing millions of years of evolutionary adaptations of plants and frugivorous animals forming networks of interactions that, ultimately, contribute to the resilience of such forests. We analyze 29 seed dispersal networks in the threatened Atlantic Forest biodiversity hotspot, with data on the frequency of feeding visits by birds to fruiting plants to answer: 1) which are the effects of forest cover and landscape connectivity on the maintenance of phylogenetic diversity (PD) of interacting birds and plants and the evolutionary distinctiveness of the interactions (EDi) between them; and 2) how EDi and plant/bird PD affects the robustness of the interaction networks? We found that forest cover positively influences both plant and bird PD and EDi. Landscape connectivity is an important predictor of bird PD, but not plant PD, suggesting that the spatial arrangement of forest remnants is essential for guaranteeing bird movement among forest fragments. Furthermore, interaction networks of areas with higher PD and EDi had great robustness to the simulated extinction of species, which underscore the importance of larger forest blocks for conserving evolutionary information and, consequently, the health and natural resistance of seed dispersal networks against environmental change.

Plant-frugivore network simplification under habitat fragmentation leaves a small core of interacting generalists

“…Specialist species are often more sensitive to habitat fragmentation than generalists 33,34 and should be lost first in small and isolated habitats, potentially reducing network nestedness 14,35,36 . Similar expectations can be formulated for network robustness in fragmented landscapes 18,37 because the high diversity of interactions on large islands should lead to lower extinction risks 14,38 . Furthermore, unique fragment environments (e.g., intense competition for food) may influence connectance 36,39 , leading to dietary niche expansion and, consequently, adding new links into a network while blurring the boundaries among network modules 36,40 .…”

Navigating through space and time: A methodological approach to quantify spatiotemporal connectivity using stream flow data as a case study

“…This framework asserts that landscape connectivity drives exchanges of matter, energy and organisms among localities within a landscape, affecting ecosystem structure, functioning and dynamics (Battin et al, 2009; Dale, 2017; Larsen et al, 2012). For example, several studies have highlighted the relevance of connectivity in driving species' diversity and abundance (Borthagaray et al, 2020; Economo & Keitt, 2010), community turnover (Epele et al, 2021; Horváth et al, 2016), population synchrony (Larsen et al, 2021; Sarremejane et al, 2021), mutualistic interactions (Ferreira et al, 2020; Monteiro et al, 2022), species' extinctions (Horváth et al, 2019), vulnerability to species invasions (Drake et al, 2017) and ecosystem services (Mitchell et al, 2013). Therefore, connectivity is emerging as one of the main drivers of community assembly and ecosystem functioning as it varies the strength of dispersal (Leibold & Chase, 2018; Thompson et al, 2020; Vellend, 2016) and affects biodiversity, which is linked to ecosystem properties such as resistance or productivity (Thompson et al, 2017; Tonkin, Heino, et al, 2018).…”

In a Neotropical Periurban Park, Fruit Consumption by Birds Seems to Be a Random Process

“…Urban environments tend to have a low number of species and interactions, resulting in simplified plant-bird frugivory and pollination networks dominated by generalists (Maruyama et al, 2019;Salazar-Rivera et al, 2020;Schneiberg et al, 2020). Conversely, forest cover and connectivity are key in the maintenance of interaction diversity in seed dispersal networks (Monteiro et al, 2021).…”