概括
在Claytonia virginica的季节性干旱条件诱导了生殖细胞中的新型染色体数. 这一新数字在两年后再次出现,表明了这种植物物种的世代周期.
科学领域:
- 植物生物学 植物生物学
- 遗传学 是一个遗传学.
- 生态生态学 生态生态学
背景情况:
- 染色体数量的变化对于植物的进化和适应至关重要.
- 环境压力因素可以影响植物种群中的遗传多样性.
- 克莱托尼亚维吉尼尼卡在染色体数量上表现出自然的变化.
研究的目的:
- 为了研究季节性环境变化对克莱托尼亚维吉尼尼卡的染色体数量的影响.
- 为了确定新染色体补充在人群中的重新出现率.
- 探索体质组织之间的染色体数量的潜在差异.
主要方法:
- 在季节变化期间对克莱托尼亚维吉尼卡种群的现场观测.
- 生殖和体细胞的细胞学分析.
- 在多个开花季度对种群遗传学的长期监测.
主要成果:
- 在生殖细胞中观察到一种新的染色体数,与接近干旱的条件相吻合.
- 新的染色体数在两年间隔后在人群中重新出现.
- 在同一植物的根和上空组织之间经常发现染色体数量的显著差异.
结论:
- 环境压力,特别是干旱,可以推动植物种群中新染色体数的出现.
- 观察到的两年复发表明了新染色体补充的世代遗传模式.
- 身体和生殖组织可以在单个Claytonia virginica植物中表现出不同的染色体构成.
相关概念视频
03:33Genetic Drift
Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...
01:09Mutation, Gene Flow, and Genetic Drift
In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
02:13Overview of Transposition and Recombination
Transposons make up a significant part of genomes of various organisms. Therefore, it is believed that transposition played a major evolutionary role in speciation by changing genome sizes and modifying gene expression patterns. For example, in bacteria, transposition can lead to conferring antibiotic resistance. Movement of transposable elements within the genetic pool of pathogenic bacteria can aid in transfer of antibiotic-resistant genetic elements. In eukaryotes, transposons can carry out...
02:39Gene Flow
Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
03:21Genome Size and the Evolution of New Genes
While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.