TY - JOUR
T1 - Heterochronic differences in fin development between latitudinal populations of the medaka Oryzias latipes (Actinopterygii
T2 - Adrianichthyidae)
AU - Kawajiri, Maiko
AU - Kokita, Tomoyuki
AU - Yamahira, Kazunori
PY - 2009/7
Y1 - 2009/7
N2 - Heterochrony is believed to have played important roles in macroevolutionary morphological changes. However, few studies have focused on intraspecific heterochrony, although interspecific differences ultimately originated from variation within ancestral species. We have demonstrated heterochrony in fin development between two latitudinal populations of the medaka, Oryzias latipes. Comparisons of fin length (anal and dorsal) among wild individuals revealed that fins are shorter with respect to body length in the northern population, indicating that they are 'paedomorphic' compared with the southern population. Observations of fin ray formation and subsequent fin growth in the laboratory revealed that the timing of pterygiophore development occurs later, and that fins start to elongate later with respect to body length in the northern fish, indicating that fin growth is 'post-displaced' compared with the southern population. In addition, the rate of fin growth with respect to body length was lower in the northern males, indicating 'neoteny'. Given that all Oryzias except O. latipes are distributed in the tropics, it is likely that higher-latitude fish have evolved post-displacement and neoteny during northern extension of their geographic range. The delayed development in higher-latitude fish is probably a trade-off for faster body growth, which has evolved as an adaptation to seasonally time-constrained environments.
AB - Heterochrony is believed to have played important roles in macroevolutionary morphological changes. However, few studies have focused on intraspecific heterochrony, although interspecific differences ultimately originated from variation within ancestral species. We have demonstrated heterochrony in fin development between two latitudinal populations of the medaka, Oryzias latipes. Comparisons of fin length (anal and dorsal) among wild individuals revealed that fins are shorter with respect to body length in the northern population, indicating that they are 'paedomorphic' compared with the southern population. Observations of fin ray formation and subsequent fin growth in the laboratory revealed that the timing of pterygiophore development occurs later, and that fins start to elongate later with respect to body length in the northern fish, indicating that fin growth is 'post-displaced' compared with the southern population. In addition, the rate of fin growth with respect to body length was lower in the northern males, indicating 'neoteny'. Given that all Oryzias except O. latipes are distributed in the tropics, it is likely that higher-latitude fish have evolved post-displacement and neoteny during northern extension of their geographic range. The delayed development in higher-latitude fish is probably a trade-off for faster body growth, which has evolved as an adaptation to seasonally time-constrained environments.
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U2 - 10.1111/j.1095-8312.2009.01233.x
DO - 10.1111/j.1095-8312.2009.01233.x
M3 - Article
AN - SCOPUS:67649854479
VL - 97
SP - 571
EP - 580
JO - Biological Journal of the Linnean Society
JF - Biological Journal of the Linnean Society
SN - 0024-4066
IS - 3
ER -