Adaptive evolution of the Populus tremula photoperiod pathway

• Environmental cues entrain the circadian clock, a core component of the photoperiod pathway in plants, to daily and seasonal changes. The circadian clock mediates input signals from light and temperature receptors to downstream target genes through feedback loops. Several studies have shown that a correct timing of the circadian system is a fitness advantage and genes in photoperiod network have been implied to evolve in response to the diversifying selection in heterogeneous environment. In an attempt to quantify the extent of the historical patterns of selection on genes in the photoperiod pathway in the widely distributed tree species European aspen (Populus tremula) we obtained sequences for twenty-five of the genes in the network and these genes were compared to patterns of nucleotide diversity in 77 randomly chosen genes from across the genome of P. tremula. We found a significant reduction in synonymous diversity in photoperiod genes while non-synonymous diversity was in line with data from control genes. A substantial fraction of the genes show signs of selection, with eight genes showing signs of rapid protein evolution. In contrast to our expectations, genes closely associated with the core circadian clock show rapid protein evolution despite their central position in the pathway. Furthermore, selection on non-synonymous mutations is negatively correlated with synonymous diversity across all genes, indicating the action of recurrent selective sweeps.

Ämnesord

NATURVETENSKAP  -- Biologi -- Annan biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Other Biological Topics (hsv//eng)

NATURVETENSKAP  -- Biologi -- Genetik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Genetics (hsv//eng)

Nyckelord

recurrent hitch-hiking

selection

populus

natural selection

sweep

Functional genomics

Funktionsgenomik

Genetics

Genetik

genetik

Genetics

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)