Answer:
Selection is a directional process that leads to an increase or a decrease in the frequency of genes or genotypes. Selection is the process that increases the frequencies of plant resistance alleles in natural ecosystems through coevolution, and it is the process that increases the frequencies of virulence alleles in agricultural ecosystems during boom and bust cycles.
Selection occurs in response to a specific environmental factor. It is a central topic of population and evolutionary biology. The consequence of natural selection on the genetic structure and evolution of organisms is complicated. Natural selection can decrease the genetic variation in populations of organisms by selecting for or against a specific gene or gene combination (leading to directional selection). It can increase the genetic variation in populations by selecting for or against several genes or gene combinations (leading to disruptive selection or balancing selection). Natural selection might lead to speciation through the accumulation of adaptive genetic differences among reproductively isolated populations. Selection can also prevent speciation by homogenizing the population genetic structure across all locations.
Selection in plant pathology is mainly considered in the framework of gene-for-gene coevolution. Plant pathologists often think in terms of Van der Plank and his concept of "stabilizing selection" that would operate against pathogen strains with unnecessary virulence. As we will see shortly, Van der Plank used the wrong term, as he was actually referring to directional selection against unneeded virulence alleles.
Answer:
1:1
Explanation:
Purines: adenine (A), guanine (G)
Pyrimidines: thymine (T), cytosine (C)
Totals:
![\left[\begin{array}{cccc}A&T&G&C\\82.4&80.8&69.1&68.4\\\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bcccc%7DA%26T%26G%26C%5C%5C82.4%2680.8%2669.1%2668.4%5C%5C%5Cend%7Barray%7D%5Cright%5D)
![\left[\begin{array}{cc}Purines&Pyrimidines\\151.5&149.2\\≈150&≈150\\ \end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7DPurines%26Pyrimidines%5C%5C151.5%26149.2%5C%5C%E2%89%88150%26%E2%89%88150%5C%5C%20%5Cend%7Barray%7D%5Cright%5D)
Answer:
Melody is a rhythmic sequence of pitches that create a musical phrase or motif. A melody also consists of two parts: pitch and rhythm. We sometimes think of melodies as the vocal part of a song. However, a melody can also be the top line of your instrumental drop, a signature bass line, or even a unique vocal sample.
Explanation:
Answer:
Due to increment in food chains.
Explanation:
Biodiversity is actually the measure of changes in the ecosystem, genetic levels and various species levels. The sea otters introduced in California over last fifty years, increased the diversity in the ecosystem as well as in species too, thus changing the biodiversity. This was the impact of increase in food web in that particular area, the number of consumers, producers and prey increased thus increasing the biodiversity.
