RESULTS
Our defaunation model included data from 58 species from 53 genera in 30
families (Table S2). With 10,000 iterations per species, this created
58,000 ‘defaunation response’ values across all defaunation scenarios.
In our additive model, the most important variable for explaining
defaunation response was seed predation (model coefficient β =
-0.153), explaining 6.82% of model variance, followed more distantly by
seedling trampling (β = -0.076, 1.69% of variance; Figure 2).
Across all species, changes in seed predation predicted defaunation
response (Figure 3A). No phenotypic traits were associated with
defaunation response across species.
Important statistical interactions emerged between seed predation and
(i) angiosperm versus gymnosperm (β = 0.146), (ii) seed mass
(β = 0.097), and (iii) specific leaf area (β = -0.073;
Figure S2). When defaunation increased seed predation, populations of
angiosperms (Figure 3B), small-seeded species (Figure 3C), and taxa with
very high specific leaf area (Figure S3) declined. Gymnosperms,
large-seeded species, and taxa with low to medium specific leaf area
were relatively unaffected by defaunation regardless of seed predation.
Several phenotypic traits were significantly correlated with species
vital rates (Table S6). Seed mass, in particular, was
positively related to juvenile
survival (r = 0.419, P = 0.001) and adult survival
(r = 0.333, P = 0.011), but was negatively related to
adult fecundity (r =
-0.354, P = 0.006). Fecundity also correlated with whether a
species was an angiosperm or a gymnosperm (r = 0.480, P< 0.001) and was positively related to tree height (r =
0.339, P = 0.009).