Seed predator preferences are associated with seed traits but an unlikely mechanism of local extinction

Abstract

Certain traits, including those that make species more vulnerable to consumption by predators, may make species inherently susceptible to population declines and local species loss (i.e. extirpation). To examine whether small mammal and arthropod granivory is a mechanism of community change via association with extirpation events, we studied seed predation on six phylogenetically paired extirpated and extant species from Kalamazoo, Michigan, using a seed removal experiment in a restored prairie. We also examined differences in granivore preferences for seed traits (seed mass, water content, C:N content) and differences in seed traits between extirpated and extant taxa. Granivory was independent of extirpation status but was affected by seed traits. Small mammals consumed more seeds than arthropods and preferentially consumed large seeds, while arthropods consumed small seeds and those with higher C:N ratios (lower nitrogen content). Extirpated and extant taxa did not differ in seed traits, perhaps explaining why they did not differ in granivory. Granivory was phylogenetically conserved, suggesting that certain plant families are more susceptible to granivores than others. This study indicates that granivory varies across species and seed traits in a prairie restoration, but does not likely influence extirpation in this system. Understanding granivore preferences may help managers predict establishment success for rare or extirpated species with particular traits being introduced into prairie restorations.

Quantifying seed rain patterns in a remnant and a chronosequence of restored tallgrass prairies in north central Missouri

“…Although it is unclear whether 2019 represents a typical or extreme year, our results show that grasslands can produce far more abundant and diverse seed rain than previously thought. Seed production in remnant prairies is likely even greater than our findings suggest due to trap obstruction from vegetation (Brown & Cahill Jr., 2020), post-dispersal seed predation (Johnson & Zettlemoyer, 2022), and secondary dispersion of seeds by wind, water, and animals (Chambers & MacMahon, 1994).…”

An all-consuming conundrum : drivers of seed predation in tallgrass prairies

“…Thus, seed predation affects both the abundance and diversity of seeds available for establishment in grassland systems, which alters species composition and diversity at the community level (Mittelbach et al 1984, Hulme 1997, Orrock et al 2003. However, the drivers of post-dispersal seed predation aren't as well-understood; the variables that influence seed predator preference is not well documented in the literature (Manson & Stiles 1998, Johnson & Zettlemoyer 2022. Thus, investigating the environmental and seed-specific variables that may influence seed predation provides a more complete representation of how plant-animal interactions alter grassland dynamics.…”