2.3.2 Network roles of fruit plants and frugivore birds
We characterized the network roles of plants and birds based on five
parameters: (1) degree (D), which describes the proportion of available
partners a species interacts with and is related to the importance of
the species for network cohesion and stability of the total number of
connected species (Costa et al., 2020); (2) species strength (Ss), which
represents the sum of the dependencies of each species’ relevance across
all partners (reflecting quantitative importance of a species for the
other) (Bascompte & Jordano, 2007); and (3) partner diversity (Pd),
which represents the diversity of interaction partners for each species.
It is a quantitative analog to the qualitative species degree, the
richness of interaction partners (Kaiser-Bunbury & Blüthgen, 2015); and
(4) effective partners (Ep), which interpret the variety of partners a
species interacts with in a given network (Quitián et al., 2017); and
(5) specialization (d´ ), which measures how strongly a species
deviates from a random sample of interaction partners, assuming that all
species interact according to their total frequencies (Rumeu et al.,
2020). All analyses were performed using the function “species-level”
in the “bipartite” package version 4.20 (Vollstädt et al., 2018).
We conducted a correlation analysis between species traits and network
parameters to test whether the role of plants and birds in the network
were driven by species traits. Plant traits included
fruit mass, fruit length, fruit
diameter, fruit volume, and fruit color, whereas bird traits included
body mass, body length, bill length, wing length, and wing-loading.
Their network parameters included degree,
species strength, partner
diversity, effective partners, and specialization. The analysis between
them was performed in the “cor” package version 4.2.0 (R Core Team,
2022), the function “pairs” were used to realize graphic
visualization, and the statistically significant difference was set asP <0.05.