Speciation is the process by which new species form. It begins with the isolation of two populations. If two populations are to become sufficiently distinct that interbreeding is difficult or impossible, then there must be relatively little gene flow (migration) between them (because if there were...
A. species B. populations C. ecosystems D. habitats 相关知识点: 试题来源: 解析 A。进化变化可以导致新物种的形成。选项 B“populations”是种群,不是进化变化的主要结果。选项 C“ecosystems”是生态系统,不是直接由进化变化形成的。选项 D“habitats”是 反馈...
Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact. 问题 句子分析(俗称“长难句分析”)是训练提高基础阅读能力的有效手段。我们通过对托福(TOEFL)、雅思(IELTS)、GRE、考研以及四六级等考试中真实出现...
Construction of a name 3.23 A species name shall consist of as few words as practicable but be distinct from names of other taxa. Species names shall not consist only of a host name and the word “virus”.Comments:Species names normally comprise more than one word. The styles used when vi...
(because if there were a great deal of gene flow, then genetic changes in one population would soon become widespread in the other as well). However, it is not enough for the two populations to simply be isolated; they will become separate species only if, during the period of isolation,...
By using a model of Hill for sampling from a finite population, the posterior moments of the number of species in the population and the posterior probability of finding a new species are obtained. Results are based on a negative binomial prior distribution on the number of species in the ...
It’s a cheeky play on the uncertainty many birders encounter when discussing this incredible species. Or on the certainty that some feel about their preferred pronunciation -- and having issues with those who choose another way. Accompanied by our cute, cartoon rendition of the bird set against...
China's National Tourism Day falls on May 19 every year starting the year of 2011. The date was chosen to commemorate the day when China's ancient travel book writer Xu Xiake (1587-1641) began writing his masterpiece "Travel Notes of Xu Xiake". Special friendship cuts across species China...
Populations of species share a gene pool: a collection of all the variants of genes in the species. Again, the basis to any changes in a group or population of organisms must be genetic for this is the only way to share and pass on traits. When variations occur within a species, they...
The vast majority of newly discovered species fall into a small number of known supergroups. Recently, however, a handful of species with no clear relationship to other supergroups have been described2,3,4, raising questions about the nature and degree of undiscovered diversity, and exposing the...