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北极熊和棕熊基因组

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发表于 2012-7-24 19:34 | 显示全部楼层 |阅读模式
本帖最后由 198401 于 2012-7-24 19:35 编辑

Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change

Webb Miller etc

Abstract

Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5–10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4–5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment.
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发表于 2012-7-25 09:19 | 显示全部楼层
没明白左边那个叉之深刻含义。
发表于 2012-7-25 11:41 | 显示全部楼层
褐色的点线代表啥?
发表于 2012-7-25 13:26 | 显示全部楼层
线粒体和常染色体的谱系不同,点线是mt,说明原北极熊的mt灭绝了?今天的mt来自棕熊?
发表于 2012-7-25 13:30 | 显示全部楼层
线粒体和常染色体的谱系不同,点线是mt,说明原北极熊的mt灭绝了?今天的mt来自棕熊?
hercules 发表于 2012-7-25 13:26

是不是北极熊抢棕熊老婆?
发表于 2012-7-25 17:20 | 显示全部楼层
玩笑话 杯具,大白熊老婆是棕色熊种
发表于 2012-7-26 01:38 | 显示全部楼层
是不是北极熊抢棕熊老婆?
狗见愁 发表于 2012-7-25 13:30


是不是大家对抢老婆都很感性趣?

从逻辑上讲,这里明显是当年的母棕熊抢了当时母白熊的老公呀。
以前的母白熊没能留下后代,说明本来属于她们的老公被抢走了,当年一定发生过熊老珠黄的母白熊跟美丽动熊的小三棕熊之间的惨烈争斗,结果还是小三们大胜而上位。

今天的女人们,熊鉴不远,慎之慎之啊。
发表于 2012-7-26 01:42 | 显示全部楼层
本帖最后由 一统浆糊 于 2012-7-26 02:39 编辑
线粒体和常染色体的谱系不同,点线是mt,说明原北极熊的mt灭绝了?今天的mt来自棕熊?
hercules 发表于 2012-7-25 13:26


是这样的,谢谢。摘要里没讲清楚。图上也没显示出常染的混合来。
文章里没测Y染色体,不知道会是什么样。
发表于 2012-7-26 11:17 | 显示全部楼层
一般认为北极熊就是棕熊演化出来的.现在北极熊和棕熊也很容易杂交啊.
发表于 2012-7-26 12:17 | 显示全部楼层
这个以前看过报导,说今天的北极熊的母系来自爱尔兰棕熊,
如果这样的话北极熊不像过去认为的那样源自美洲了?
发表于 2013-1-31 14:46 | 显示全部楼层
曾经发现了所谓的新物种   棕白熊   北极灰熊。。。  被商业狩猎打死的一只  是棕父  白母
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