Adaptive differences in gene expression in European flounder (Platichthys flesus).
Population structure was previously believed to be very limited or absent in classical marine fishes, but recently, evidence of weakly differentiated local populations has been accumulating using noncoding microsatellite markers. However, the evolutionary significance of such minute genetic differences remains unknown. Therefore, in order to elucidate the relationship between genetic markers and adaptive divergence among populations of marine fishes, we combined cDNA microarray and microsatellite analysis in European flounders (Platichthys flesus). We demonstrate that despite extremely low levels of neutral genetic divergence, a high number of genes were significantly differentially expressed between North Sea and Baltic Sea flounders maintained in a long-term reciprocal transplantation experiment mimicking natural salinities. Several of the differentially regulated genes could be directly linked to fitness traits. These findings demonstrate that flounders, despite little neutral genetic divergence between populations, are differently adapted to local environmental conditions and imply that adaptation in gene expression could be common in other marine organisms with similar low levels of population subdivision.
Larsen
Peter F
PF
Danish Institute for Fisheries Research, Technical University of Denmark, Vejlsøvej 39, DK-8600 Silkeborg, Denmark. pfl@difres.dk
Nielsen
Einar E
EE
Williams
Timothy D
TD
Hemmer-Hansen
Jakob
J
Chipman
James K
JK
Kruhøffer
Mogens
M
Grønkjaer
Peter
P
George
Stephen G
SG
Dyrskjøt
Lars
L
Loeschcke
Volker
V
D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D005432:Flounder / Q000235:genetics* / Q000502:physiology; D015870:Gene Expression; D020869:Gene Expression Profiling; D005819:Genetic Markers; D014644:Genetic Variation; D018895:Microsatellite Repeats; D020411:Oligonucleotide Array Sequence Analysis; D012623:Seawater / Q000737:chemistry; D012965:Sodium Chloride / Q000378:metabolism
D005819:Genetic Markers; D012965:Sodium Chloride