Anticipating Spring: Wild Populations of Great Tits (Parus major) Differ in Expression of Key Genes for Photoperiodic Time Measurement

• Measuring day length is critical for timing annual changes in physiology and behavior in many species. Recently, rapid changes in several photoperiodically-controlled genes following exposure to a single long day have been described. Components of this 'first day release' model have so far only been tested in highly domesticated species: quail, sheep, goats and rodents. Because artificial selection accompanying domestication acts on genes related to photoperiodicity, we must also study this phenomenon in wild organisms for it to be accepted as universal. In a songbird, the great tit (Parus major), we tested whether a) these genes are involved in photoperiodic time measurement (PTM) in a wild species, and b) whether predictable species and population differences in expression patterns exist. Using quantitative RT-PCR, we compared gene expression after a single long day in male great tits from Sweden (57 degrees 42'N) with that from a German (47 degrees 43'N) population. Hypothalamic gene expression key for PTM changed only in the northern population, and occurred earlier after dawn during the single long day than demonstrated in quail; however, gonadotropins (secretion and synthesis) were stimulated in both populations, albeit with different timing. Our data are the first to show acute changes in gene expression in response to photostimulation in any wild species not selected for study of photoperiodism. The pronounced differences in gene expression in response to a single long day between two populations raise exciting new questions about potential environmental selection on photoperiodic cue sensitivity.

Ämnesord

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

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

Nyckelord

zonotrichia-leucophrys-gambelii

white-crowned sparrow

type-2

deiodinase gene

japanese-quail

deep brain

median-eminence

nerve-terminals

lh-secretion

long-day

hormone

llett bk

1974

proceedings of the national academy of sciences of the united states of

llett bk

1975

general and comparative endocrinology

v26

p126

llett bk

1969

nature

v223

p968

ster rg

1994

neuroscience and biobehavioral reviews

v18

p541

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