Home About us Contact
|
Home About us Contact | ||
|
|
||
Latitudinal Populations (latitudinal + population)
Selected AbstractsEffects of red, far-red and blue light in maintaining growth in latitudinal populations of Norway spruce (Picea abies)PLANT CELL & ENVIRONMENT, Issue 2 2006JØRGEN ALEXANDER MØLMANN ABSTRACT Seedlings of trees with a free growth pattern cease growth when night-lengths become shorter than a critical value, and this critical night-length (CNL) decreases with increasing latitude of origin. In northern populations, the light quality also appears to play an important role and a clinal variation in requirement for far-red (FR) light has been documented. In this study we dissected the light quality requirements for maintaining growth in different latitudinal populations of Norway spruce (Picea abies (L.) H. Karst.) using light emitting diodes for red (R), FR and blue (B) light, as 12 h day extension to provide 24 h photoperiod. At equal spectral photon flux, FR light was more effective than R light in maintaining growth, and the requirement of both R and FR increased with northern latitude of origin. One-to-one mixtures of R and FR light were more effective in maintaining growth than either FR or R light alone, indicating a possible interaction between R and FR light maintaining growth. Using the blue light as day extension could not prevent growth cessation in any of the populations, but delayed the bud set slightly in all populations. Our results suggest that phytochrome(s) are the primary photoreceptors in high irradiance responses maintaining growth in Norway spruce seedlings. [source] Heterochronic differences in fin development between latitudinal populations of the medaka Oryzias latipes (Actinopterygii: Adrianichthyidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009MAIKO KAWAJIRI 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. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 571,580. [source] | ||||||||||