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SEXUAL PARTNERS FOR THE STRESSED: FACULTATIVE OUTCROSSING IN THE SELF‐FERTILIZING NEMATODE CAENORHABDITIS ELEGANS
Author(s) -
Morran Levi T.,
Cappy Brian J.,
Anderson Jennifer L.,
Phillips Patrick C.
Publication year - 2009
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.1558-5646.2009.00652.x
Subject(s) - biology , outcrossing , selfing , facultative , mating , asexual reproduction , mating system , sexual reproduction , evolutionary biology , inbreeding depression , genetic fitness , genetics , experimental evolution , adaptation (eye) , caenorhabditis elegans , genetic diversity , inbreeding , ecology , population , gene , pollen , demography , neuroscience , sociology
Sexual reproduction shuffles genetic variation, potentially enhancing the evolutionary response to environmental change. Many asexual organisms respond to stress by generating facultative sexual reproduction, presumably as a means of escaping the trap of low genetic diversity. Self‐fertilizing organisms are subject to similar genetic limitations: the consistent loss of genetic diversity within lineages restricts the production of variation through recombination. Selfing organisms may therefore benefit from a similar shift in mating strategy during periods of stress. We determined the effects of environmental stress via starvation and passage through the stress‐resistant dauer stage on mating system dynamics of Caenorhabditis elegans , which reproduces predominantly through self‐fertilization but is capable of outcrossing in the presence of males. Starvation elevated male frequencies in a strain‐specific manner through differential male survival during dauer exposure and increased outcrossing rates after dauer exposure. In the most responsive strain, the mating system changed from predominantly selfing to almost exclusively outcrossing. Like facultative sex in asexual organisms, facultative outcrossing in C. elegans may periodically facilitate adaptation under stress. Such a shift in reproductive strategy should have a major impact on evolutionary change within these populations and may be a previously unrecognized feature of other highly selfing organisms.