GENETICS OF INCIPIENT SPECIATION IN DROSOPHILA MOJAVENSIS. III. LIFE-HISTORY DIVERGENCE IN ALLOPATRY AND REPRODUCTIVE ISOLATION

William J. Etges, Cassia Cardoso de Oliveira, Mohamed A. F. Noor, Michael G. Ritchie

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

We carried out a three-tiered genetic analysis of egg-to-adult development time and viability in ancestral and derived populations of cactophilic Drosophila mojavensis to test the hypothesis that evolution of these life-history characters has shaped premating reproductive isolation in this species. First, a common garden experiment with 11 populations from Baja California and mainland Mexico and Arizona reared on two host species revealed significant host plant X region and population interactions for viability and development time, evidence for host plant adaptation. Second, replicated line crosses with flies reared on both hosts revealed autosomal, X chromosome, cytoplasmic, and autosome X cactus influences on development time. Viability differences were influenced by host plants, autosomal dominance, and X chromosomal effects. Many of the F-1, F-2, and backcross generations showed evidence of heterosis for viability. Third, a QTL analysis of male courtship song and epicuticular hydrocarbon variation based on 1688 Baja x mainland F-2 males also revealed eight QTL influencing development time differences. Mainland alleles at six of these loci were associated with longer development times, consistent with population-level differences. Eight G x E interactions were also detected caused by longer development times of mainland alleles expressed on a mainland host with smaller differences among Baja genotypes reared on the Baja host plant. Four QTL influenced both development time and epicuticular hydrocarbon differences associated with courtship success, and there was a significant QTL-based correlation between development time and cuticular hydrocarbon variation. Thus, the regional shifts in life histories that evolved once D. mojavensis invaded mainland Mexico from Baja California by shifting host plants were genetically correlated with variation in cuticular hydrocarbon-based mate preferences.

Original languageEnglish
Pages (from-to)3549-3569
Number of pages21
JournalEvolution
Volume64
Issue number12
DOIs
Publication statusPublished - Dec 2010

Keywords

  • Adaptation
  • life-history evolution
  • quantitative genetics
  • speciation
  • EPICUTICULAR HYDROCARBON COMPOSITION
  • CACTOPHILIC DROSOPHILA
  • ECOLOGICAL SPECIATION
  • PREMATING ISOLATION
  • CUTICULAR HYDROCARBONS
  • FATTY-ACIDS
  • MONKEYFLOWERS MIMULUS
  • ISOLATED POPULATIONS
  • NATURAL-SELECTION
  • SEXUAL ISOLATION

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