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Sex determination and the evolution of dioecy from monoecy in Sagittaria latifolia (Alismataceae).

Abstract

The role of mutations of small versus large effect in adaptive evolution is of considerable interest to evolutionary biologists. The major evolutionary pathways for the origin of dioecy in plants (the gynodioecy and monoecy-paradioecy pathways) are often distinguished by the number of mutations involved and the magnitude of their effects. Here, we investigate the genetic and environmental determinants of sex in Sagittaria latifolia, a species with both monoecious and dioecious populations, and evaluate evidence for the evolution of dioecy via gynodioecy or monoecy-paradioecy. We crossed plants of the two sexual systems to generate F1, F2 and backcross progeny, and grew clones from dioecious populations in low-and high-fertilizer conditions to examine sex inconstancy in females and males. Several lines of evidence implicate two-locus control of the sex phenotypes. In dioecious populations sex is determined by Mendelian segregation of alleles, with males heterozygous at both the male- and female-sterility loci. In monoecious populations, plants are homozygous for alleles dominant to male sterility in females and recessive to female sterility in males. Experimental manipulation of resources revealed sex inconstancy in males but not females. These results are consistent with predictions for the evolution of dioecy via gynodioecy, rather than the expected monoecy-paradioecy pathway, given the ancestral monoecious condition.

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  • Authors+Show Affiliations

    ,

    Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario MSS 3B2, Canada.

    Source

    MeSH

    Biological Evolution
    Crosses, Genetic
    Genetics, Population
    Infertility
    Models, Genetic
    Reproduction
    Sagittaria
    Sex Determination Processes

    Pub Type(s)

    Comparative Study
    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    15058400

    Citation

    TY - JOUR T1 - Sex determination and the evolution of dioecy from monoecy in Sagittaria latifolia (Alismataceae). AU - Dorken,Marcel E, AU - Barrett,Spencer C H, PY - 2004/4/3/pubmed PY - 2004/5/1/medline PY - 2004/4/3/entrez SP - 213 EP - 9 JF - Proceedings. Biological sciences / The Royal Society JO - Proc. Biol. Sci. VL - 271 IS - 1535 N2 - The role of mutations of small versus large effect in adaptive evolution is of considerable interest to evolutionary biologists. The major evolutionary pathways for the origin of dioecy in plants (the gynodioecy and monoecy-paradioecy pathways) are often distinguished by the number of mutations involved and the magnitude of their effects. Here, we investigate the genetic and environmental determinants of sex in Sagittaria latifolia, a species with both monoecious and dioecious populations, and evaluate evidence for the evolution of dioecy via gynodioecy or monoecy-paradioecy. We crossed plants of the two sexual systems to generate F1, F2 and backcross progeny, and grew clones from dioecious populations in low-and high-fertilizer conditions to examine sex inconstancy in females and males. Several lines of evidence implicate two-locus control of the sex phenotypes. In dioecious populations sex is determined by Mendelian segregation of alleles, with males heterozygous at both the male- and female-sterility loci. In monoecious populations, plants are homozygous for alleles dominant to male sterility in females and recessive to female sterility in males. Experimental manipulation of resources revealed sex inconstancy in males but not females. These results are consistent with predictions for the evolution of dioecy via gynodioecy, rather than the expected monoecy-paradioecy pathway, given the ancestral monoecious condition. SN - 0962-8452 UR - https://www.unboundmedicine.com/medline/citation/15058400/Sex_determination_and_the_evolution_of_dioecy_from_monoecy_in_Sagittaria_latifolia__Alismataceae__ L2 - http://rspb.royalsocietypublishing.org/cgi/pmidlookup?view=long&pmid=15058400 ER -