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Relative importance of pollen and seed dispersal across a N eotropical mountain landscape for an epiphytic orchid
Author(s) -
Kartzinel Tyler R.,
Shefferson Richard P.,
Trapnell Dorset W.
Publication year - 2013
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.12551
Subject(s) - biological dispersal , gene flow , biology , genetic structure , pollen , pollinator , genetic diversity , epiphyte , ecology , seed dispersal , colonization , pollination , habitat , evolutionary biology , genetic variation , gene , population , genetics , demography , sociology
Populations of many species are isolated within narrow elevation bands of N eotropical mountain habitat, and how well dispersal maintains genetic connectivity is unknown. We asked whether genetic structure of an epiphytic orchid, E pidendrum firmum, corresponds to gaps between C osta R ican mountain ranges, and how these gaps influence pollen and seed flow. We predicted that significant genetic structure exists among mountain ranges due to different colonization histories and limited gene flow. Furthermore, we predicted that pollen movement contributes more to gene flow than seeds because seeds are released into strong winds perpendicular to the narrow northwest–southeast species distribution, while the likely pollinators are strong fliers. Individuals from 12 populations and three mountain ranges were genotyped with nuclear microsatellites (n DNA ) and chloroplast sequences (cp DNA ). Genetic diversity was high for both markers, while n DNA genetic structure was low ( F STn = 0.020) and cp DNA structure was moderate ( F STc = 0.443). Significant cp DNA barriers occurred within and among mountain ranges, but n DNA barriers were not significant after accounting for geographic distance. Consistent with these contrasting patterns of genetic structure, pollen contributes substantially more to gene flow among populations than seed ( m p / m s = 46). Pollinators mediated extensive gene flow, eroding n DNA colonization footprints, while seed flow was comparatively limited, possibly due to directional prevailing winds across linearly distributed populations. Dispersal traits alone may not accurately inform predictions about gene flow or genetic structure, supporting the need for research into the potentially crucial role of pollinators and landscape context in gene flow among isolated populations.