Liapkov S M, Cherdantsev V G, Cherdantseva E M
Zh Obshch Biol. 2008 Jan-Feb;69(1):25-43.
Females reproductive, size, and age characteristics were studied in isolated local populations of Rana arvalis in the southern and northern parts of its range. The yearlings of the southern populations used to get larger by their first overwintering due to earlier beginning of the breeding season, as compared with the yearlings of the northern population. As a result, "southern" females become sexually mature at the age of two years while the "northern" ones become mature at the age of three years. This causes geographic differences in age composition among two populations, the "southern" reproductive females being younger on average than the "northern" ones. The earlier female maturation in the first case is not compensated by respective rise of the growth rate; to the contrary, the "southern" females grow more slowly during the first two years of their life and appear to be smaller than the "norhern" ones. These reproduction and growth patterns arise supposedly due to paedomorphosis, which causes specific reproductive characteristics, namely decrease in the egg size, increase in the reproductive effort and more strong correlation between female fertility and body size. Local and geographic differences are expressed not in the extent but in the structure of reproductive pattern, as no negative correlation was revealed between female reproductive age and body size in the southern populations. Southern habitats cannot be considered as "unfavourable with respect to body size", so the geographic differences under consideration cannot be explained by optimization of the reproductive strategies at population level. Paedomorphosis appears as a result of the female maturation rate possessing a wider norm of reaction than the growth rate. At the same time, fixation of the specific growth rate narrows norm of reaction of some other characters important for the phenotype reproductive fitness thus predetermining their subsequent evolution.
在其分布范围的南部和北部，对孤立的当地林蛙种群的雌性繁殖、体型和年龄特征进行了研究。与北部种群的一岁龄林蛙相比，南部种群的一岁龄林蛙由于繁殖季节开始较早，在首次越冬前体型会变得更大。结果，“南部”雌性在两岁时性成熟，而“北部”雌性在三岁时性成熟。这导致两个种群在年龄组成上存在地理差异，“南部”繁殖雌性的平均年龄比“北部”的要小。在第一种情况下，雌性早熟并没有因生长速度的相应提高而得到补偿；相反，“南部”雌性在生命的头两年生长得更慢，而且看起来比“北部”雌性更小。这些繁殖和生长模式可能是由于幼态延续导致的，幼态延续会产生特定的繁殖特征，即卵的大小减小、繁殖投入增加以及雌性繁殖力与体型之间的相关性更强。局部和地理差异不是表现在繁殖模式的程度上，而是表现在其结构上，因为在南部种群中未发现雌性繁殖年龄与体型之间存在负相关。南部的栖息地不能被认为是“不利于体型发育的”，因此所考虑的地理差异不能用种群水平上繁殖策略的优化来解释。幼态延续的出现是因为雌性成熟速度的反应规范比生长速度的反应规范更宽。与此同时，特定生长速度的固定缩小了对表型繁殖适应性重要的其他一些特征的反应规范，从而决定了它们随后的进化。
