Genetica

, Volume 129, Issue 2, pp 167–177

Hybridization, recombination, and the genetic basis of fitness variation across environments in Avena barbata

  • Robert G. Latta
  • Kyle M. Gardner
  • April D. Johansen-Morris
Original Paper

Abstract

We created Recombinant Inbred Lines (RILs) derived from a cross between ecotypes of Avena barbata associated with moist (mesic) and dry (xeric) habitats in California. Traits which were correlated with fitness across RILs mapped to the same Quantitative Trait Loci (QTLs) as fitness. However, different QTL affected fitness in different environments so that fitness was weakly correlated across environments. Recombination released considerable heritable variation both in fitness, and in ecologically relevant traits. Many traits showed transgressive segregation caused by recombination of QTL associated in repulsion phase in the parents. In addition, some traits were uncorrelated, allowing novel combinations of those traits to be created. Recombination also created heritable variation in reaction norms for at least one trait (root allocation). Altogether these results suggest that recombination can combine the most selectively advantageous genes and traits of the parents to produce broadly adapted genotypes that are capable of outperforming the parents. Indeed, two of the RILs showed higher fitness than the parental ecotypes across a range of environmental treatments in the greenhouse, but their superiority was less pronounced in the field. Although late-generation recombinants exhibited hybrid breakdown, being less fit, on average, than the mid-parent, early generation hybrids appear to exhibit hybrid vigour through the expression of dominance effects in the heterozyotes. This vigour may offset the effects of hybrid breakdown in the early generations following a cross, enhancing the opportunity for recombination to create broadly adapted genotypes. We discuss the implications of these findings to the evolution of colonizing species.

Keywords

Coadapted gene complex Epistasis Generalist/specialist Line cross analysis QTL mapping Transgressive segregation 

Abbreviations

QTL

Quantitative trait locus

RIL

Recombinant inbred line

RMR

Root mass ratio

GxE

Genotype by environment interaction

HREC

Hopland Research and Extension Center

SFREC

Sierra Foothills Research and Extension Center

AFLP

Amplified fragment length polymorphism

Copyright information

© Springer Science+Business Media B.V. 2006

Authors and Affiliations

  • Robert G. Latta
    • 1
  • Kyle M. Gardner
    • 1
  • April D. Johansen-Morris
    • 1
  1. 1.Department of BiologyDalhousie UniversityHalifaxCanada

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