Environmentally determined juvenile growth rates dictate the degree of sexual size dimorphism in the Sardinian brook newt
Environmentally determined juvenile growth rates dictate the degree of sexual size dimorphism in the Sardinian brook newt
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DOI：
10.1007/s10682-014-9717-8
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发表时间：
2015-01-01
影响因子：
1.9
通讯作者：
Bovero, Stefano
中科院分区：
文献类型：
--
作者：
Angelini, Claudio;Sotgiu, Giuseppe;Bovero, Stefano
两性大小二态性（SSD）在两栖动物中广泛存在，它被归因于生殖力选择，用于雌性偏向的SSD物种，性选择，通常用于雄性偏向的SSD物种，或其他形式的自然选择。此外，SSD在群体水平上与体型变异性相互作用。通过使用男性偏向SSD蝾螈（Euproctus platycephalus）作为模式物种，我们调查了整个物种范围内的身体大小和SSD变异性，撒丁岛，寻找SSD背后的主要进化力量。我们发现身体大小和SSD的地理变化：蝾螈从北方人口一般大于南方的，与男性偏见的二型性在前者的程度更大。蝾螈的平均年龄在不同的种群中有所不同，但它并不遵循任何地理模式，也没有性别差异。南方种群性成熟早于北方种群，成熟度与温度呈正相关。生长曲线表明，北方人口达到男性偏向SSD之前达到性成熟，而在南方男性成为大于女性6岁后，以下的非渐近生长曲线。成年体大小变化的地理模式是由于更北的种群中较大蝾螈的成熟延迟，以及由于南部种群的温度较高而导致的性成熟较早，这导致较小的体型。SSD的变化与身体的大小一致：这是明显的，在北方，性双成熟造成较大的男性，但它是弱的，在南方，温暖的温度造成了两性的成熟较早。
Sexual size dimorphism (SSD) is widespread among amphibians, and it is attributed to fecundity selection, invoked for female-biased-SSD species, sexual selection, usually invoked for male-biased-SSD species, or other forms of natural selection. Further, SSD interplays with body size variability at population level. By using a male-biased-SSD newt (Euproctus platycephalus) as model species, we investigated body size and SSD variability across the whole species' range, the island of Sardinia, looking for the main evolutionary force behind SSD. We found geographic variation of body size and SSD: newts from northern populations were generally larger than those from southern ones, with a larger degree of male biased dimorphism in the former. The mean age of newts varied among populations, but it did not follow any geographical pattern, and it did not differ between sexes. Southern populations reached sexual maturity earlier than northern ones, and maturity was positively correlated with temperature. Growth curves show that northern populations achieved male-biased SSD before reaching sexual maturity, whilst in the south males become larger than females after 6 years in age, following a non-asymptotic growth curve. The geographical pattern of the adult body size variation is attributable to delayed maturation of the larger newts in more northerly populations, and earlier sexual maturation due to warmer temperature in southern populations, which leads to smaller body size. SSD varies consistently with body size: it is evident in the north, where sexual bimaturation caused larger males, but it is weak in the south, where warmer temperature caused an earlier maturation of both sexes.