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Fly‐pollinated Pleurothallis (Orchidaceae) species have high genetic variability: evidence from isozyme markers
Author(s) -
Borba Eduardo L.,
Felix Juliana M.,
Solferini Vera N.,
Semir João
Publication year - 2001
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2657106
Subject(s) - biology , orchidaceae , pollinator , pollination , inbreeding depression , population , allopatric speciation , inbreeding , evolutionary biology , ecology , pollen , demography , sociology
We conducted an isozyme study in 22 populations of five Pleurothallis (Orchidaceae) species (12 loci in nine enzymatic systems). The genetic variability in all populations is surprisingly high ( P = 58–83%, A = 2.1–3.8, H e = 0.25–0.43) in spite of the fact that the five species are pollinated by small flies whose behavior enables self‐pollination. We suggest that self‐incompatibility, inbreeding depression, and mechanical barriers that prevent self‐pollination in these species are responsible for the maintainance of the high genetic variability. These traits are uncommon in Orchidaceae, but have been observed in these and some other species pollinated by flies or other pollinators with behavior that facilitates self‐pollination. The genetic similarity among conspecific populations is also high for species with very short‐range flying pollinators. Only one population of P. teres presented values of genetic similarity lower than usually observed in allopatric conspecific populations. Morphology, however, does not support its segregation as a new taxon. All species can be recognized by their enzymatic patterns, and the results agree with recently proposed taxonomic realignments. Conversely, the supposed affinities among these species based on floral morphology are not supported, and we hypothesize that it may be due to convergence in species with similar pollinators.