EXPLOSIVE CENOZOIC VOLCANISM AND CLIMATIC IMPLICATIONS
EXPLOSIVE CENOZOIC VOLCANISM AND CLIMATIC IMPLICATIONS
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DOI：
10.1126/science.196.4295.1231-a
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发表时间：
1977-01-01
期刊：
影响因子：
56.9
通讯作者：
THUNELL, RC
中科院分区：
文献类型：
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作者：
KENNETT, JP;THUNELL, RC
关于新生代火山爆发和气候影响，女性中有22人怀孕(表1)。这与栖息地盐草根茎的萌发不谋而合。因此，对照种群开始生殖活动的时间比处理过的岛屿种群晚了大约6周。我们在1975-1976年的冬天重复了这一制度，但在12月24日的冬天早些时候开始了实验。这一过程的基础是我们假设，在先前的实验中，雄性在这两个区域都对增加的光周期做出了反应。我们假设，在接近冬至的时候开始实验重演，可能会更清楚地展示男性对补充麦草的反应。此外，我们使用了两个试验区，岛上和几百码外的大陆上的另一个区域。两个大陆控制区也被使用。其中一个控制区直接毗邻大陆实验区，但与大陆实验区之间有一条大约10米宽的冰水通道。对发芽小麦的处理于1975年12月27日开始，1976年1月10日结束。结果(表2)与之前的实验结果相似，尽管怀孕率较低。这并不出人意料，因为到目前为止，这些动物还没有经历过光周期增加的刺激影响。因此，对麦草刺激的反应可能会有更大的时间滞后。此外，饲喂期间的大雪使麦草的消耗量比之前的试验减少了约50%。尽管如此，来自实验区的所有雌性(表2)都是在卵子中有大的发育中的卵泡的妊娠者。同样，来自控制区的雌性动物中没有一只怀孕，这些动物的卵巢缺乏发育的卵泡。同样，在那些接受草类补充剂的人群中，男性性腺发育也受到显著影响。试验区男性平均配对睾丸重量为89.9±38.0 mg(N=10)，而对照组为28.3±11.2 mg(N=9)(P<；01，t检验)。睾丸的组织学检查表明，与对照地区的动物相比，70%的处理动物已经开始活跃的精子生成，而没有精子生成。来自对照地区的连续采样表明，直到1976年4月，未处理的种群才开始正常繁殖。这些结果是明确的经验--
On Explosive Cenozoic Volcanism and Climatic Implications females, 22 were pregnant (Table 1). This coincided with the sprouting of salt grass rhizomes in the habitat. Thus, the control population initiated reproductive activity approximately 6 weeks later than the treated island population. We replicated the regime inthe winter of 1975-1976 but began the experiment earlier in the winter, on 24December. The basis for this procedure was our hy-pothesis that males in the previous ex-periment had responded in both areas to increasing photoperiod. We hypothesized that beginning the experimental re-gime closer to the winter solstice might more clearly demonstrate male responses to the wheatgrass supplement. In addition, we used two experimental areas, the island and another area on the mainland several hundred yards away. Two mainland control areas were also used. One of the control areas was located directly adjacent to the mainland experimental area but was separated from it by a channel of water and ice ap-proximately 10 m wide. The treatment with sprouted wheat began on 27 December 1975 and ended on 10 January 1976. The results (Table 2) were similar to those of the earlier experiment, although the incidence of pregnancies was lower. This was not unexpected, as the animals would not as yet have experienced the stimulating influence of increasing photoperiod. Hence, a somewhat greater time lag could be expected in response to the wheatgrass stimulus. Further, heavy snowfall during the feeding period result-ed in about 50 percent less consumption of wheatgrass than in the previous exper-iment. Nonetheless, all but one of the females from the experimental areas (Table 2) were either pregnantor cycling with large developing follicles in the ova-ries. Again, none of the females from the control areas were pregnant, and the ovaries from these animals lacked devel-oping follicles. Similarly, male gonadal development was significantly affectedin those populations receiving the grass supplements. Males from the experimen-tal areas had a mean paired testicular weight of 89.9+ 38.0 mg (N= 10) as compared to a mean testicular weight of 28.3+ 11.2 mg (N= 9) in the control areas (P<. 01, t-test). Histological ex-amination of the testes demonstrated that 70 percent of the treated animals had begun active spermatogenesis as com-pared to no spermatogenesis in animals from the control areas. Continued sam-pling fromthe control areas demonstrated that the normal onset ofbreeding in the untreated populations did not oc-cur until April 1976. These results are unequivocal experi-