Adaptive divergence in resistance to herbivores in Datura stramonium

• Published in: PeerJ (San Francisco, CA) Vol. 3; p. e1411
• Main Authors: Castillo, Guillermo, Valverde, Pedro L, Cruz, Laura L, Hernández-Cumplido, Johnattan, Andraca-Gómez, Guadalupe, Fornoni, Juan, Sandoval-Castellanos, Edson, Olmedo-Vicente, Erika, Flores-Ortiz, César M, Núñez-Farfán, Juan
• Format: Journal Article
• Language: English
• Published: United States PeerJ. Ltd 26.11.2015; PeerJ, Inc; PeerJ Inc
• Subjects: Adaptive divergence; Animal behavior; Atropine; Datura stramonium; Divergence; Ecology; Evolution; Evolutionary biology; Evolutionary Studies; Gene flow; Genetic distance; Genetic drift; Herbivores; Heritability; Leaf trichomes; Natural selection; Plant defense; Plant resistance; Population; Population differentiation; Population genetics; PST–FST comparison; Quantitative genetics; Scopolamine; Solanaceae; Tropane alkaloids; Genetic drift and restricted gene flow; Leaf trichomes; Adaptive divergence; Datura stramonium; Plant resistance; PST–FST comparison; Plant defense; Divergent natural selection; Tropane alkaloids
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.1411

Defensive traits exhibited by plants vary widely across populations. Heritable phenotypic differentiation is likely to be produced by genetic drift and spatially restricted gene flow between populations. However, spatially variable selection exerted by herbivores may also give rise to differences among populations. To explore to what extent these factors promote the among-population differentiation of plant resistance of 13 populations of Datura stramonium, we compared the degree of phenotypic differentiation (P ST) of leaf resistance traits (trichome density, atropine and scopolamine concentration) against neutral genetic differentiation (F ST) at microsatellite loci. Results showed that phenotypic differentiation in defensive traits among-population is not consistent with divergence promoted by genetic drift and restricted gene flow alone. Phenotypic differentiation in scopolamine concentration was significantly higher than F ST across the range of trait heritability values. In contrast, genetic differentiation in trichome density was different from F ST only when heritability was very low. On the other hand, differentiation in atropine concentration differed from the neutral expectation when heritability was less than or equal to 0.3. In addition, we did not find a significant correlation between pair-wise neutral genetic distances and distances of phenotypic resistance traits. Our findings reinforce previous evidence that divergent natural selection exerted by herbivores has promoted the among-population phenotypic differentiation of defensive traits in D. stramonium.