Premium
Microevolution in agricultural environments: how a traditional Amerindian farming practice favours heterozygosity in cassava ( Manihot esculenta Crantz, Euphorbiaceae)
Author(s) -
Pujol Benoît,
David Patrice,
McKey Doyle
Publication year - 2005
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2004.00708.x
Subject(s) - microevolution , biology , cutting , loss of heterozygosity , manihot esculenta , domestication , agriculture , euphorbiaceae , microbiology and biotechnology , population , botany , agroforestry , horticulture , allele , genetics , ecology , demography , sociology , gene
We demonstrate a novel case of selection for heterozygosity in nature, involving inadvertent human selection on a population of domesticated plants. Amerindian farmers propagate cassava ( Manihot esculenta ) clonally by cuttings. Seedlings also appear spontaneously in fields, and farmers allow them to grow, later using some for cuttings. These ‘volunteers’ contribute new genotypes. However, many are inbred, whereas multiplied clones are highly heterozygous. We demonstrate the selective retention of heterozygous volunteers. When farmers weeded fields, they killed small volunteers, but retained large ones. Plant size and heterozygosity were correlated, and both increased after weeding. The process we document allows maintenance of genotypically diverse and heterozygous clonal stocks. Demonstrating heterosis in nature usually requires large sample sizes, but novel features of our system allowed escape of this constraint. Traditional agroecosystems offer unusual opportunities for the microevolutionary studies required to give on‐farm conservation of genetic resources a solid scientific basis.