怎么举报偷税漏税:甲虫 乱叫

来源:百度文库 编辑:偶看新闻 时间:2024/03/29 01:27:48
生物学家们一直想搞清一个问题:为什么一些雌性动物不辞辛劳地进行多角恋爱呢?对于雄性动物来讲,它们可以将自己的精子传播得尽可能遥远、尽可能广泛,这样做的意义是它们可以生下更多的后代。然而,对于雌性动物来讲,额外的性活动会对其身体造成伤害,有可能会减少寿命,而这样做并不能增加到处散播自己基因的可能性。现在,研究人员证明了雌性动物的乱交也有自己的益处。通过多性伴交配,雌性动物可以弥补近亲繁殖带来的不利因素,这就是乱交在小种群动物中发展起来的原因。 When populations of many organisms are small, their members often wind up mating with kin. Such inbreeding can lead to a double dose of bad genes that result in sickly offspring and reduced fertility. Matthew Gage, an evolutionary ecologist at the University of East Anglia in the United Kingdom, wanted to know if promiscuous females could offset problems from inbreeding by providing more possibilities for their eggs to be fertilized by genetically suitable sperm. He and his colleagues tested this idea in the red flour beetle, a 3-millimeter-long insect pest found in flour and grains and sometimes used in laboratory studies. 在许多生物中,当种群数量很少的时候,种群中的成员最终往往发生近亲交配现象。这样的近亲交配会导致双倍的有害基因,生产的后代多病,而且生殖力有所下降。英国东安格利亚大学的进化生物学家马修·盖奇想了解乱交的雌性动物是否能够为自己的卵提供更多机会,来选择适于遗传的精子来授精,以抵消近亲繁殖带来的问题。盖奇及同事利用赤拟谷盗(red flour beetle)检验了这一想法。赤拟谷盗是一种体长3毫米的昆虫类害虫,存在于面粉和谷物中,有时也用在实验室研究中。 Gage and colleagues found that multiple mating, also called polyandry, did benefit inbred females. When allowed to mate with just one male, inbred females have 50% fewer surviving offspring than outbred counterparts that mated with nonkin. But the number of offspring is equal if the inbred females breed with five males, the team reports today in Science. The inbred females are apparently able to weed out sperm from kin that would lead to less fit offspring. If they mate with just one male, however, they don't have that option. 盖奇及同事发现:雌性多性伴交配(也叫一雌多雄式交配)对于近亲繁殖的雌性动物的确有好处。今天,研究人员在《科学》杂志上报道说:只允许近亲繁殖的赤拟谷盗跟一只雄性交配的时候,其后代的存活率比跟非近亲交配的远系繁殖后代的存活率低50%;但是,如果让近亲繁殖的雌性跟五只雄性交配,两种繁殖方式的后代存活率相同。显然,近亲繁殖的雌性能够剔除来自近亲的精子,以免造成不够健康的后代。然而,如果这些雌性只跟一只雄性交配,那么它们就无法进行这样的选择。 The researchers also examined whether promiscuity could evolve in inbred beetles. They first created inbred beetles by mating sisters with brothers for several generations. Then they allowed multiple populations of the inbred strains to pass through 15 generations with no interference from the researchers. The researchers also raised outbred populations for comparison. Gage and his colleagues assessed the females' promiscuity by watching them interact with a series of 10 males presented to them one at a time. 研究人员还审查了乱交现象是否会在近亲繁殖的甲虫中延续下去。他们首先让兄弟姐妹之间进行交配,经过几代后创造出近亲繁殖的甲虫。然后,他们让这些近亲繁殖品种的多个群落在不受研究人员干预的情况下经历15代。研究人员还饲养了远系繁殖的种群,以便进行对比。盖奇及同事将10只为一组的雄性甲虫呈现在雌性面前,每次呈现一只,通过观察跟雄性的交往情况,评定了这些雌性甲虫的乱交倾向。 The inbred females became fast and loose compared with their outbred counterparts. They were quicker to start mating, and they hooked up with males more frequently and for a longer time, the researchers report. They also produced more surviving offspring.  跟远系繁殖的雌性甲虫相比,那些近亲繁殖的雌性更加放荡。研究人员报道:它们更加急于开始交配,而且它们跟雄性交合得更加频繁,交合的时间也更长。这些雌性也能够生产出更多可以存活下来的后代。 "No other work has shown that inbreeding over evolutionary time frames also changes female behavior," says Rhonda Snook, an evolutionary biologist at the University of Sheffield in the United Kingdom, who was not involved in the study.  “其他的研究工作都没有证明这一点:在进化期间近亲繁殖也改变了雌性的行为,”英国设菲尔德大学进化生物学家朗达·斯努克说。斯努克没有参加这项研究。 "The issue of multiple mating by females is a long-standing conundrum in biology," adds G?ran Arnqvist, an evolutionary biologist at Uppsala University in Sweden, who was not associated with the study. "This [work] suggests one scenario in which multiple mating can be beneficial." In theory, females in small populations of other species should follow suit. “长期以来,雌性动物多性伴交配问题是生物界的难以解答的问题,”瑞典乌普萨拉大学的进化生物学家高兰·阿恩科维斯特补充道,“该研究提出了一种设想:雌性多性伴交配可能是有益的。”阿恩科维斯特也没有参与这项研究。从理论上讲,其他小种群物种中的雌性也应该效仿甲虫。