The influences of progenitor filtering, domestication selection and the boundaries of nature on the domestication of grain crops

GARIBALDI, L.A.; AIZEN, M.A; SAEZ, A.; GLEISER, G.; STRELIN, M.; HARDER, L.D.

FUNCTIONAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021 vol. 35 p. 1998 - 2011

0269-8463

1. Domestication generally involves two sequential processes: initial identificationof wild species with desirable characteristics (?progenitor filtering?) and subsequentartificial and natural selection that, respectively, improve features preferredby humans and adapt species to cultivation/captivity (?domestication selection?).Consequently, domesticated species can differ from wild species and may sharecharacteristics owing to convergent evolution (?domestication syndrome?). Baringevolutionary constraints, domestication selection may generate extreme phenotypesthat transcend the ?boundaries of nature? evident for wild species. Despiteevidence of domestication syndromes in some clades, broader contributions ofprogenitor filtering and domestication selection to characteristics of contemporarydomesticated species have received limited attention.2. Using comparative analysis of 49 grain-cropand 87 wild annual plant species from15 families, we (1) addressed whether plants of crop and wild species differ formean seed number, per-seedmass and total seed-massinvestment; (2) assessedcontributions of (a) progenitor filtering and (b) domestication selection to thesedifferences; (3) evaluated whether crop characteristics exceed the boundaries ofnature and (4) assessed whether seed-productioncharacteristics of grain cropsconstitute components of a generic domestication syndrome.3. On average, grain-cropplants produce heavier seeds and greater total seed massthan wild species, but seed number per plant does not differ. Comparison of wildspecies between genera with or without crop species found no evidence of progenitorfiltering. In contrast, crop species differed from congeneric wild speciesfor the mass traits, but not for seed number. Greater seed investment by cropsis consistent with artificial selection for enhanced seed yield (mass per harvestedarea), whereas heavier individual seeds suggest selection for improved nutritionalquality and (or) adaptation to cultivation environments.4. Seed number?sizecharacteristics of grain-cropspecies lie within the bivariatevariation among wild species and so do not exceed the boundaries of nature. Seednumber and size varied similarly between species types and generally aligned withseed-investmentisoclines, suggesting an upper investment limit.