The relative contributions of seed and pollen dispersal to gene flow and genetic diversity in seedlings of a tropical palm

Abstract

Seed and pollen dispersal shape patterns of gene flow and genetic diversity in plants. Pollen is generally thought to travel longer distances than seeds, but seeds determine the ultimate location of gametes. Resolving how interactions between these two dispersal processes shape microevolutionary processes is a long-standing research priority. We unambiguously isolated the separate and combined contributions of these two dispersal processes in seedlings of the animal-dispersed palm Oenocarpus bataua to address two questions. First, what is the spatial extent of pollen versus seed movement in a system characterized by long-distance seed dispersal? Second, how does seed dispersal mediate seedling genetic diversity? Despite evidence of frequent long-distance seed dispersal, we found that pollen moves much further than seeds. Nonetheless, seed dispersal ultimately mediates genetic diversity and fine-scale spatial genetic structure. Compared to undispersed seedlings, seedlings dispersed by vertebrates were characterized by higher female gametic and diploid seedling diversity and weaker fine-scale spatial genetic structure for female gametes, male gametes and diploid seedlings. Interestingly, the diversity of maternal seed sources at seed deposition sites (N ) was associated with higher effective number of pollen sources (N ), higher effective number of parents (N ) and weaker spatial genetic structure, whereas seed dispersal distance had little impact on these or other parameters we measured. These findings highlight the importance maternal seed source diversity (N ) at frugivore seed deposition sites in driving emergent patterns of fine-scale genetic diversity and structure.

Life history, climate and biogeography interactively affect worldwide genetic diversity of plant and animal populations

“…These studies demonstrated that species distributed around the Equator have higher overall genetic diversity (i.e., GD S ) than species occurring near the poles, and that GD S is lower for long-lived or low-fecundity species than for short-lived or high-fecundity species. However, contrary to GD P (Supplementary Notes 1) 52,53 , GD S is insensitive to local-scale processes ruled for instance by environmental constraints, biogeographic features or anthropogenic stressors. As opposed to GD S , GD P can thus be linked to local community dynamics through its relationship with population fitness, which in turn affects the ability of species to compete and interact with co-occurring species 12,54,55 .…”

Habitat loss and fragmentation reduce effective gene flow by disrupting seed dispersal in a neotropical palm

“…In this study, we directly compared the relative contribution of male gametes from pollen sources and female gametes from seed sources to patterns of genetic diversity and structure of established seedlings of the canopy palm Oenocarpus bataua across a fragmented landscape in northwest Ecuador experiencing ongoing habitat loss and fragmentation. We compared seedlings in fragments to seedlings in nearby continuous forest reserve (Browne, Ottewell, Sork, & Karubian, in press). Seeds of O. bataua are dispersed by large‐bodied vertebrates capable of long‐distance seed dispersal, whereas pollen is dispersed by beetles and other insects (Karubian et al., ; Núñez‐Avellaneda & Rojas‐Robles, ).…”

Directional seed and pollen dispersal and their separate effects on anisotropy of fine‐scale spatial genetic structure among seedlings in a dioecious, wind‐pollinated, and wind‐dispersed tree species, Cercidiphyllum japonicum

“…Therefore, seed dispersal critically affects shaping the FSGS as in other studies (Browne et al, 2018;Grivet et al, 2009;Nakanishi et al, 2009). This result is expected because seed dispersal transports both male and female gametes and determines the final locations of genotypes (Browne et al, 2018;Grivet et al, 2009). Pollen dispersal may frequently exceed the examined scale for seedlings, as indicated by the mean distance (870.6 m).…”