PMID- 21714822
OWN - NLM
STAT- MEDLINE
DCOM- 20111209
LR  - 20211203
IS  - 1365-294X (Electronic)
IS  - 0962-1083 (Linking)
VI  - 20
IP  - 15
DP  - 2011 Aug
TI  - The parallel evolution of dwarfism in Arctic charr is accompanied by adaptive 
      divergence in mTOR-pathway gene expression.
PG  - 3167-84
LID - 10.1111/j.1365-294X.2011.05172.x [doi]
AB  - Ecological factors have a major role in shaping natural variation in body size, 
      although the underlying mechanisms are poorly understood. Icelandic Arctic charr 
      (Salvelinus alpinus L.) populations represent an ideal model to understand 
      body-size evolution, because adult dwarfism has arisen independently on multiple 
      occasions in response to parallel environmental pressures. The mechanistic target 
      of rapamycin (mTOR) pathway transmits signals from the environment to control 
      cellular growth and is a primary candidate to be under selection for the dwarf 
      phenotype. To test this hypothesis, we modified 'inputs' to this pathway in five 
      dwarf and two generalist populations (with ancestral life history and body-size 
      traits), using a standardized manipulation of food intake in a common 
      environment. The skeletal muscle transcript levels of 21 mTOR-pathway genes were 
      quantified in 274 individuals ( approximately 6000 datapoints), and statistical modelling was 
      used to elucidate sources of variation. Constitutive expression differences 
      between populations were the main component of variation for around 
      three-quarters of the studied genes, irrespective of nutritional-state and 
      body-size phenotype. There was evidence for stabilizing selection acting among 
      populations, conserving the nutritionally dependent regulation of pathway genes 
      controlling muscle atrophy. There were three genes (mTOR, 4E-BP-1 and IGFBP4), 
      where the expression variation between dwarf and generalist populations exceeded 
      the between-population variation. Divergence in the expression of these candidate 
      adaptive genes was most evident during a period of rapid growth following 
      sustained fasting and was directionally consistent with their functions 
      regulating growth and protein synthesis. We concluded that selection has operated 
      efficiently to shape gene expression evolution in Icelandic charr populations and 
      that the regulation of certain mTOR-pathway genes evolved adaptively in locations 
      favouring dwarfism, resulting in reduced muscle protein accretion under 
      growth-favouring conditions.
CI  - (c) 2011 Blackwell Publishing Ltd.
FAU - Macqueen, Daniel J
AU  - Macqueen DJ
AD  - Scottish Ocean Institute, School of Biology, University of St Andrews, St 
      Andrews, Fife, UK. djm59@st-andrews.ac.uk
FAU - Kristjansson, Bjarni K
AU  - Kristjansson BK
FAU - Paxton, Charles G M
AU  - Paxton CG
FAU - Vieira, Vera L A
AU  - Vieira VL
FAU - Johnston, Ian A
AU  - Johnston IA
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20110629
PL  - England
TA  - Mol Ecol
JT  - Molecular ecology
JID - 9214478
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
SB  - IM
MH  - Adaptation, Physiological/*genetics
MH  - Animals
MH  - *Biological Evolution
MH  - Body Size/genetics
MH  - Environment
MH  - Female
MH  - Gene Expression Regulation
MH  - Gene-Environment Interaction
MH  - Genetics, Population
MH  - Male
MH  - Muscle, Skeletal/metabolism
MH  - Phenotype
MH  - TOR Serine-Threonine Kinases/*genetics
MH  - Trout/*genetics/*growth & development
EDAT- 2011/07/01 06:00
MHDA- 2011/12/14 06:00
CRDT- 2011/07/01 06:00
PHST- 2011/07/01 06:00 [entrez]
PHST- 2011/07/01 06:00 [pubmed]
PHST- 2011/12/14 06:00 [medline]
AID - 10.1111/j.1365-294X.2011.05172.x [doi]
PST - ppublish
SO  - Mol Ecol. 2011 Aug;20(15):3167-84. doi: 10.1111/j.1365-294X.2011.05172.x. Epub 
      2011 Jun 29.