Hawkmoth and bee pollinators impact pollen dispersal at the landscape but not local scales in two species of Oenothera

Abstract

Premise: Animal pollinators play an important role in pollen dispersal. Here, we assessed differences in pollen and seed dispersal and the role of pollinator functional groups with different foraging behaviors in generating patterns of genetic diversity over similar geographic ranges for two closely related taxa. We focused on two members of Oenothera section Calylophus (Onagraceae) that co-occur on gypsum outcrops throughout the northern Chihuahuan Desert but differ in floral phenotype and primary pollinator: Oenothera gayleana (bee) and O. hartwegii subsp. filifolia (hawkmoth).

Methods: We measured breeding system and floral traits and studied gene flow and population differentiation at the local (<13 km; four populations) and landscape (60-440 km; five populations) scales using 10-11 nuclear (pollen dispersal) and three plastid (seed dispersal) microsatellite markers.

Results: Both taxa were self-incompatible and floral traits were consistent with expectations for different pollinators. Seed and pollen dispersal patterns were distinctly different for both species. We found no evidence of genetic structure at the local scale but did at the landscape scale; O. gayleana showed greater differentiation and significant isolation by distance than in O. hartwegii subsp. filifolia. The plastid data were consistent with gravity dispersal of seeds and suggest that pollen dispersal is the principal driver of genetic structure in both species.

Conclusions: We demonstrated that pollinator functional groups can impact genetic differentiation in different and predictable ways. Hawkmoths, with larger foraging distances, can maintain gene flow across greater spatial scales than bees.

Publisher

Wiley

Publication Date

6-1-2023

Publication Title

American Journal of Botany

Department

Biology

Document Type

Article

DOI

https://dx.doi.org/10.1002/ajb2.16156

Notes

Special Issue: Pollen as the Link Between Phenotype and Fitness

Keywords

Population genetic structure, See dispersal, Foraging ranges, F-statistics, Flow, Plant, Differentiation, Diversity, Software, Patterns

Language

English

Format

text

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