- UID
- 1333346
- 在线时间
- 小时
- 注册时间
- 2018-3-14
- 最后登录
- 1970-1-1
- 主题
- 帖子
- 性别
- 保密
|
鹿和学原文
Body-size comparisons of alpine- and forest-wintering woodland caribou herds in the Yukon
Gerald W Kuzyk, Michael M Dehn, Richard S Farnell
Canadian Journal of Zoology, 1999, 77(7): 1017-1024, https://doi.org/10.1139/z99-053
说道两种caribou,一种在Forest找东西吃,一种在alpine找东西吃
某位鸟人发现一种鹿的体型特征和snow depth有关。然后为了肯定这一相关性,该鸟人做了两个对照试验,排除了同样两个可能造成该体型特征的他因
有一篇阅读是研究鹿的,说是那个学者最开始认为鹿的特征不同是因为过冬区域不同,在深雪区过冬的鹿和浅雪区的鹿的身体特征比如腿不一样长啊什么的,后来又否定了这个假设,转向研究是不是因为nutrition不同所以身体特征不同,这里比较了一下森林过冬鹿和alpine过冬鹿
ABSTRACT
Information from radiotelemetry studies has shown that woodland caribou (Rangifer tarandus caribou) living in the snow-shadow region of the southwest part of the Yukon spend part of the winter in the subalpine and alpine zones. Other woodland caribou living in areas with high snowfall in central and eastern Yukon have traditional winter ranges in forested lowlands. We theorize that selective forces exerted by the wintering environments will have induced differences in caribou body characteristics, and we test the hypothesis that woodland caribou that winter in the alpine zone are phenotypically different from those wintering in forested environments. We compared five physical measurements from 382 female woodland caribou in 11 Yukon herds. Our results indicate a significant (14 cm) difference in shoulder height between forest- and alpine-wintering groups, but provide no support for the hypothesis that the difference is due to snow depth. There were no significant differences in other body measurements or in body proportions. It is also unlikely that the difference in shoulder height is due to winter nutrition, since body condition scores did not differ between forest- and alpine-wintering groups. We discuss seasonal nutrition, predation, and migration as alternative explanations for our results.
Introduction
The role of snow as a selective force in shaping caribou (Rangifer sp.) morphology and behavior was noted by early researchers (Formozov 1946, Pruitt 1959). Edwards (1956), in studying ungulate mortality rates in relation to snow depth, reviewed the early literature and noted that most ungulate populations living in areas of occasional high snow regimes may experience periodic die-offs, ultimately due to deep snow. He noted that there was no evidence, possibly because of a lack of scientific study, that deep snow causes high mortality rates in caribou. Caribou (Rangifer tarandus) ranked highest of 11 North American mammal species in a study of their ability to cope with snow conditions (Telfer and Kelsall 1984). Stardom (1975) presented the first detailed study of the behavior of woodland caribou (Rangifer tarandus caribou) movement patterns related to snow parameters and commented on their morphological adaptations for dealing with snow.
Woodland caribou in the central part of the Yukon are thought to be integrades between the smaller barren-ground caribou (Rangifer tarandus granti) of northern Yukon and the larger woodland caribou to the south (Banfield 1961; Gauthier and Farnell 1986). Selective factors that may play an important role in determining leg length in Rangifer spp. include foraging efficiency in snow, food availability, movement during migration, and speed related to predator avoidance (Klein et al. 1987).
第二篇:(转自Clarkfeng,为什么不比我早考一天。。)某个学者对Caribou的研究。学者提出观点说Caribou的特点和处在的环境有关, 特别是对雪的厚度的回应。 说道两种caribou,一种在Forest找东西吃,一种在alpine找东西吃。 作者研究说,因为冬天forest 里面的雪的厚度大,所以应该推断出forest 里面的caribou have bigger shoulder and chest to ground distance.研究表明,在Forest里面的caribou确实有一些可以从理论推导出的特点, 但是其他特点不具有代表性,因为其他特点在两种caribou中差别不是一致的。 然后学者又提出了另外一个观点,说是caribou摄取的nutrition导致了他们的不同。接下来就讲着这个观点的内容。 但是又有事实证明这个理论也不完整。 (40-45 line)
K原来提出了它们具有几个...特点(比如腿长)
In Scandinavia, mountain reindeer wintering in areas of low and windswept snow are smaller than forest reindeer that winter in areas of high soft snow (Nieminen and Helle 1980). In Yukon, some woodland caribou herds winter in alpine and subalpine areas, while others winter in forested valleys. Relative snow depths in these areas are determined by major geological features (Oswald and Senyk 1977). We hypothesize that differences in body characteristics among woodland caribou herds may be due to an evolutionary response to snow conditions on their winter range. We provide data and examine differences in body size and body proportions of woodland caribou herds living at approximately the same latitude but in different ecological regimes (Farnell et al. 1996; Farnell et al. 1998). If caribou that winter in forested areas are selected to deal with greater snow depths more effectively, we would expect them to be taller at the shoulder, have greater clearance between the ground and their chest, and have proportionately longer legs. This could confer an advantage in terms of foraging opportunities, namely when digging feeding craters in deep snow.
Woodland caribou in the Yukon are classified, based on their wintering foraging behavior, as a mountain/terrestrial ecotype, and they feed on terrestrial, not arboreal, lichen during winter (Farnell et al. 1998). A woodland caribou herd is defined as a group of caribou with a common winter range that is separated geographically from neighboring populations (Edmonds 1988; Farnell et al. 1996). Herd fidelity is determined by radio-collaring caribou on the herds’ winter ranges and follow lichening their seasonal movements for 2–3 years (Farnell et al. 1998). This has been recently supported on a genetic basis using microsatellite DNA fingerprinting (Zittlau et al. 1999) and supports the conceptual framework of herd identity. Herd sizes in this study ranged from 400 (Tatchun) to 6000 (Finlayson). Populations are generally stable, except for the Chisana herd, which is declining (Farnell et al. 1998).
Discussion and conclusions
作者研究说,因为冬天forest 里面的雪的厚度大,所以应该推断出forest 里面的caribou have bigger shoulder and chest to ground distance.研究表明,在Forest里面的caribou确实有一些可以从理论推导出的特点, 但是其他特点不具有代表性,因为其他特点在两种caribou中差别不是一致的。
There is a tendency for caribou in alpine-wintering herds to be smaller than those in forest herds when shoulder height, chest height, and hind-foot length are compared, as shown in Table 3 and Fig. 2. Although this difference is significant at the overall level, it is less clear at the herd level. When a subset of the herds is classified into extreme low- snow and high-snow herds, the overall size differences are statistically significant (Table 5), but when individual herds are compared (Fig. 4) the tendency of alpine-wintering herds to be smaller does not hold for chest height (where Nahanni, a forest herd, is smallest).
Are alpine-wintering herds less “leggy” than forest-wintering herds? The comparison of body proportions (Table 4) indicates that while shoulder height/total length and shoulder height/heart girth ratios are significantly lower in alpine-wintering herds, chest height as a proportion of total length or heart girth is not. When body proportions are compared on the low-snow versus high-snow continuum (Table 6), only shoulder height/heart girth is significantly different. Similarly, multiple comparisons of the herds (Figs. 3 and 5) show no strong trend on any of the variables.
K原来提出了它们具有几个...特点(比如腿长)
某位鸟人发现一种鹿的体型特征和snow depth有关。然后为了肯定这一相关性,该鸟人做了两个对照试验,排除了同样两个可能造成该体型特征的他因
While forest-wintering herds tend to be composed of larger individuals, this difference manifests itself clearly only in shoulder height. The data set provides no support for the hypothesis that any difference which may exist is due to selection on the basis of snow depth, because there is no clearly significant trend toward relatively longer legs in herds that winter where snow depths are greater.
While it is possible that relative snow depths, and the frequency of occurrence of very deep snow, might have been different in the past, and that the differences noted above may indeed be due to such selection, the age of the major geological features that determine the location of snow-shadow areas suggests that this is not the case.
Is it possible that the herds are not sufficiently isolated genetically for selection to have occurred? We feel that our use of caribou herds as separate populations in the analysis is justified on the basis of recent genetic research which has shown Yukon caribou herds to be virtually distinct populations (Zittlau et al. 1999). This information, obtained using DNA fingerprinting, which is part of a larger ongoing study examining herd fidelity, indicates that three caribou herds’ ranges separated by distances ranging from 58 to 160 km are genetically different. Limited genetic exchange between herds was noted and could be explained by a low incidence of dispersal.
然后学者又提出了另外一个观点,说是caribou摄取的nutrition导致了他们的不同
K原来提出了它们具有几个...特点(比如腿长)
題目:問本來k推這理論的目的 選:環境不同鹿發展不一樣
Better nutrition may also explain the greater shoulder height of forest-wintering caribou. Klein (1968) found a body-size response in caribou that were introduced into areas of previously ungrazed, high-quality forage. Captive barren-ground caribou calves on a higher nutritional plane had a faster skeletal growth rate, as determined by hind-foot length, than wild calves from the same herd (McEwan and Wood 1966). In a study of three Norwegian wild reindeer herds, those with access to favorable forage were found to have calves 2–3 weeks earlier, which could allow for a longer growing season for calves (Reimers et al. 1983). Because late-winter body condition scores did not differ between alpine- and forest-wintering herds in our study (Table 3), we conclude that body-size differences were not due to nutritional constraints. We would expect that if caribou were nutritionally stressed at any time of year, it would clearly show in winter body condition scores. Moreover, favorable pregnancy rates are linked to favorable nutrition levels (Cameron and Ver Hoef 1994). Pregnancy rates for herds in this study (R.S. Farnell, unpublished data) conform to the mean of 86% found for North American caribou (Bergerud 1980).
We present some data in order to examine the hypothesis that predation pressure affects caribou leg length (Klein et al. 1987). Wolves are the primary cause of natural mortality of adult woodland caribou in the Yukon (Farnell et al. 1996). At present, wolf densities in the two areas are similar: 5.6/1000 km2 in the alpine area and 7.5/1000 km2 in the forest area. However, it is pack density, or number of “hunting units” per area, that have the greatest impact on caribou predation (Hayes 1995). Densities are similar: 1.03 packs/ 1000 km2 in alpine areas and 1.07 packs/1000 km2 in forest areas (A. Baer, unpublished data). We have no historical data on wolf numbers and are therefore unable to reject this hypothesis, even though it could be argued from our current data that this is unlikely.
We reject the hypothesis that migration is a selective force on caribou leg length (Klein et al. 1987), as woodland caribou make relatively short (<100 miles; 1 km = 1.609 km) seasonal altitudinal migrations (Farnell et al. 1998). This may be a force influencing barren-ground caribou that make long latitudinal migrations between calving and winter ranges.
In summary, we found what appears to be a substantive difference in shoulder height between forest- and alpine- wintering caribou, but no evidence that this difference represents a response to snow depth. At the same time we argue that the differences are probably not accounted for by any of the alternative hypotheses that we have identified: differences in nutritional regime, predation pressure, or the demands of migration. It is possible that a complex of factors affects the herds’ body characteristics to such an extent that the effect of snow depth is masked. It may also be that the geographic distance between our study herds is too small to allow any selective factors affecting body characteristics to be detected, therefore it may be more instructive to compare body characteristics over a larger geographic area, such as between subarctic and arctic caribou.
2017-8-2 19:49:35
第二篇其实也不难,是一个自然题,说的大致是两个生物和雪的厚度的关系,后来证明没关系。然后别人不服气,说和雪的nutrition有关,后来做了实验,又没关。然后又证明和别的其他也没关系。
2017-8-5 22:37:57
关于鹿和雪补充一下!!
还有一篇关于woodland地区的caribou。反正就是科学家假设两个地区的winter condition会影响鹿的体征,同时发现这个地方的鹿高度和脚趾长度(?)不同,一个地方的smaller,可能是由雪的深度导致的,这一个区别也的确导致更大的那一方更适合雪多的环境。但是胸腔什么的数据没有太大的区别。排除了snow depth的影响。
另外文章的后半部分主要是提出可能是由一个食物导致的区别(似乎是forage这个词)。但是这两种鹿的营养状况并没有区别,出生率也没有区别。(大概暗示就是食物也无法解释)
【本月原始】洛家庄的灯
有一篇阅读是研究鹿的,说是那个学者最开始认为鹿的特征不同是因为过冬区域不同,在深雪区过冬的鹿和浅雪区的鹿的身体特征比如腿不一样长啊什么的,后来又否定了这个假设,转向研究是不是因为nutrition不同所以身体特征不同,这里比较了一下森林过冬鹿和alpine过冬鹿
【本月原始】wowwow08
某位鸟人发现一种鹿的体型特征和snow depth有关。然后为了肯定这一相关性,该鸟人做了两个对照试验,排除了同样两个可能造成该体型特征的他因。第一个试验是和另一种鹿比,发现虽然有的体型特征有差异,但是别的没有。第二个试验记不清楚了,还待其他狗主补充。
【本月原始】emily6354565
2. 鹿和雪深的關係
P1:K說鹿的身體構造不同可能是因爲生活環境的關係 他認為在森林裡的鹿的腳會比較長 因爲雪比較深 跟住在另一個地方的鹿比
但發現鹿的腳好像沒有不同 只有shoulder 和 chest的高度有差異
P2:貌似後來發現跟雪深沒關 應該是跟nutrition 有關
但最後證明跟nutrition也沒關 因為好像是證據顯示跟推論相反之類的(例森林鹿應該要比較高但證據卻比較低)還有其他特徵不同的原因未知
題目:問本來k推這理論的目的 選:環境不同鹿發展不一樣
【本月原始】CheeJo
4.好像是关于deep雪地里caribou的特点。K原来提出了它们具有几个...特点(比如腿长),但是做了一个对比实验,发现好像不能印证。
后来有研究是不是食物的nutrition不一样,但是好像也没有显著的结果支持。
【本月原始】洛家庄的灯
有一篇阅读是研究鹿的,说是那个学者最开始认为鹿的特征不同是因为过冬区域不同,在深雪区过冬的鹿和浅雪区的鹿的身体特征比如腿不一样长啊什么的,后来又否定了这个假设,转向研究是不是因为nutrition不同所以身体特征不同,这里比较了一下森林过冬鹿和alpine过冬鹿
【本月原始】emily6354565
2. 鹿和雪深的關係
P1:K說鹿的身體構造不同可能是因爲生活環境的關係 他認為在森林裡的鹿的腳會比較長 因爲雪比較深 跟住在另一個地方的鹿比
但發現鹿的腳好像沒有不同 只有shoulder 和 chest的高度有差異
P2:貌似後來發現跟雪深沒關 應該是跟nutrition 有關
但最後證明跟nutrition也沒關 因為好像是證據顯示跟推論相反之類的(例森林鹿應該要比較高但證據卻比較低)還有其他特徵不同的原因未知
題目:問本來k推這理論的目的 選:環境不同鹿發展不一樣
https://forum.chasedream.com/thread-116154-1-1.html
第二篇:(转自Clarkfeng,为什么不比我早考一天。。)某个学者对Caribou的研究。学者提出观点说Caribou的特点和处在的环境有关, 特别是对雪的厚度的回应。 说道两种caribou,一种在Forest找东西吃,一种在alpine找东西吃。
作者研究说,因为冬天forest 里面的雪的厚度大,所以应该推断出forest 里面的caribou have bigger shoulder and chest to ground distance.研究表明,在Forest里面的caribou确实有一些可以从理论推导出的特点, 但是其他特点不具有代表性,因为其他特点在两种caribou中差别不是一致的。
然后学者又提出了另外一个观点,说是caribou摄取的nutrition导致了他们的不同。接下来就讲着这个观点的内容。 但是又有事实证明这个理论也不完整。 (40-45 line)
|
本帖子中包含更多资源
您需要 登录 才可以下载或查看,没有帐号?立即注册
x
|