title: Life-history evolution and density-dependent growth in experimental populations of yeast.
abstract: We studied the evolution of the correlation between growth rate r and yield K in experimental lineages of the yeast Saccharomyces cerevisiae. First, we isolated a single clone every approximately 250 generations from each of eight populations selected in a glucose-limited medium for 5000 generations at approximately 6.6 population doublings per day (20 clones per line × 8 lines) and measured its growth rate and yield in a new, galactose-limited medium (with ∼1.3 doubling per day). For most lines, r on galactose increased throughout the 5000 generations of selection on glucose whereas K on galactose declined. Next, we selected these 160 glucose-adapted clones in the galactose environment for approximately 120 generations and measured changes in r and K in galactose. In general, growth rate increased and yield declined, and clones that initially grew slowly on galactose improved more than did faster clones. We found a negative correlation between r and K among clones both within each line and across all clones. We provide evidence that this relationship is not heritable and is a negative environmental correlation rather than a genetic trade-off.
authors.affiliation: Department of Biology, Wake Forest University, Winston-Salem, North Carolina 27106, USA. jnjasmin@gmail.com
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Jasmin
authors.forename: Clifford
authors.initials: C
authors.lastname: Zeyl
mesh_terms: D005075:Biological Evolution; D005690:Galactose; D005947:Glucose; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D012641:Selection, Genetic
chemical_list: D005947:Glucose; D005690:Galactose