Consequences of intraspecific variation in seed dispersal for plant demography, communities, evolution and global change

Abstract

As the single opportunity for plants to move, seed dispersal has an important impact on plant fitness, species distributions and patterns of biodiversity. However, models that predict dynamics such as risk of extinction, range shifts and biodiversity loss tend to rely on the mean value of parameters and rarely incorporate realistic dispersal mechanisms. By focusing on the mean population value, variation among individuals or variability caused by complex spatial and temporal dynamics is ignored. This calls for increased efforts to understand individual variation in dispersal and integrate it more explicitly into population and community models involving dispersal. However, the sources, magnitude and outcomes of intraspecific variation in dispersal are poorly characterized, limiting our understanding of the role of dispersal in mediating the dynamics of communities and their response to global change. In this manuscript, we synthesize recent research that examines the sources of individual variation in dispersal and emphasize its implications for plant fitness, populations and communities. We argue that this intraspecific variation in seed dispersal does not simply add noise to systems, but, in fact, alters dispersal processes and patterns with consequences for demography, communities, evolution and response to anthropogenic changes. We conclude with recommendations for moving this field of research forward.

Seed‐to‐seedling transitions exhibit distance‐dependent mortality but no strong spacing effects in a Neotropical forest

“…By assuming fixed dispersal and recruitment kernels at the species level, our model ignores intraspecific variation driven by local conditions, even though such variation may have both positive and negative effects on interspecific coexistence (Snell et al, 2019 . Median (solid line) and 50% credible interval (shaded area) of the relative probability of survival, calculated as the ratio of new recruit and seed kernels, or 20-cm seedling and recruit kernels, as a function of dispersal distance r. Each curve is scaled to a median of 1 across the range of distances considered.…”

“…By assuming fixed dispersal and recruitment kernels at the species level, our model ignores intraspecific variation driven by local conditions, even though such variation may have both positive and negative effects on interspecific coexistence (Snell et al, 2019). Although we model the average dispersal kernel across years, the results could be misleading if the inter annual variation in dispersal was correlated with that of fecundity, for example, if specialist animal dispersers behave differently in years of low and high seed production for a given species.…”

Progress Towards Plant Community Transcriptomics: Pilot RNA-Seq Data from 24 Species of Vascular Plants at Harvard Forest

“…Trancriptome profiling or genome sequencing of multiple species and individuals within a community will open new, integrative avenues of analyses and allow us to address existing questions that require sampling of floras and communities (Bragg et al, 2015;Fitzpatrick and Keller, 2015;Bowsher et al, 2017;Han et al, 2017;Swenson and Jones, 2017;Zambrano et al, 2017;Matthews et al, 2018;Subrahmaniam et al, 2018;Breed et al, 2019) . This is especially true for understanding responses to climate change where community level analyses are needed to capture the interacting dynamics of different species responses (Liu et al, 2018;Komatsu et al, 2019;Snell et al, 2019) . The integration of community level genomic data from non-model species with ecological and trait data will improve our understanding of plant responses to climate change.…”

Partitioning intraspecific variation in seed dispersal potential using a low‐cost method for rapid estimation of samara terminal velocity

“…However, these models tend to use single mean values of seed terminal velocity and other dispersal traits to represent a species as a whole (e.g., Hemrová, Bullock, Hooftman, White, & Münzbergová, 2017;Heydel, Cunze, Bernhardt-Römermann, & Tackenberg, 2015;Nathan, Horvitz, et al, 2011): within-species variation in dispersal traits is often not captured, or just from a few individuals, and within-individual variation tends to be overlooked entirely (Teller, Marden, & Shea, 2015). As recent work highlights (Herrera, 2017;Snell et al, 2019;Teller et al, 2015), within-species and within-individual variation in dispersal traits may be considerable, and has the capacity to significantly affect predictions of seed dispersal. Such variation may also have important evolutionary and ecological implications.…”