Reproduction and growth in a precocial small mammal, Cavia magna
Reproduction and growth in a precocial small mammal, Cavia magna
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DOI：
10.1644/1545-1542(2005)086
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发表时间：
2005-08-01
影响因子：
1.7
通讯作者：
Künkele, J
中科院分区：
文献类型：
--
作者：
Kraus, C;Trillmich, F;Künkele, J
小型哺乳动物通常会产生大量的晚期幼仔，导致高繁殖率。相比之下，经过长时间的妊娠，狒狒很少会生出早熟的幼崽。这种繁殖策略的代价是低的内在自然增长率。我们调查了是否在野生种群的豚鼠繁殖模式是一致的假设，即豚鼠可以增加其繁殖输出的季节性繁殖和成熟极早。我们收集的数据，繁殖和增长的捕获-再捕获在26个月的实地研究，在乌拉圭的湿地，并从实验室人口与来自同一地区的个人成立。在Caviinae中，C.麦格纳是特别早熟，与个别新生儿体重平均18%的母亲质量。繁殖主要是季节性的，主要的出生季节开始于9月底（南方春季），分别延伸到1999年5月和2000年2月，只有少数女性在第1个但不是第2个南方冬季繁殖。每只雌性每年平均产3窝。一些在早春出生的雌性在30至45天之间成功受孕，与实验室中的雌性相似。第一个春季队列的其余部分和随后出生队列的女性将繁殖推迟到第二年春季。身体状况和生长速度在春季最高，全年下降，并在年度之间变化，可能是决定是否成年女性或少年开始繁殖的最接近的因素。在条件允许的情况下，机会主义的繁殖可能会部分补偿低繁殖率的鳄鱼。
Small mammals usually produce large litters of altricial young, resulting in high reproductive rates. In contrast, cavies give birth to few precocial young after a long gestation. The price of this reproductive strategy is a low intrinsic rate of natural increase. We investigated if the patterns of reproduction in a wild population of Cavia magna are consistent with the hypotheses that cavies can increase their reproductive output by breeding aseasonally and by maturing extremely early. We collected data on reproduction and growth by capture-recapture during a 26-month field study in a wetland in Uruguay, and from a laboratory population founded with individuals from the same region. Among the Caviinae, C. magna is particularly precocial, with individual neonates weighing on average 18% of maternal mass. Reproduction was mostly seasonal, with the main birth season starting at the end of September (austral spring) and extending until May in 1999 and February in 2000, respectively, with only a few females reproducing during the 1st but not the 2nd austral winter. Individual females produced on average 3 litters per year. Some females born in early spring conceived successfully between the age of 30 and 45 days, similar to females in the laboratory. The remainder of the 1st spring cohort and females of subsequent birth cohorts delayed reproduction until the following spring. Body condition and growth rates were highest in the spring, declined through the year, and varied between years, and may be the proximate factors deten-nining whether an adult female or a juvenile initiates breeding. Breeding opportunistically whenever conditions allow might partly compensate for the low reproductive rate of cavies.