Comparative case studies offer detailed insight into the causal mechanisms, processes, policies, motivations, decisions, beliefs and constraints facing actors — which statistics, large-scale surveys and cultural historiographies often struggle to explain. As we discussed in week 1, case-oriented approaches place the integrity of the case, not variables, center-stage. The language of variables, not the case, dominate the research process of variable-oriented comparative work. It shines a light on a bigger argument. Since the case is often constructed on the basis of a specific outcome or theory of interest, case selection is purposive i.
Selection process is the process of employment of the appropriate people who are considered to be more skillful and helpful for the organization than other applicants. Selection process is carried out in every public and private organization and is most widespread in business. Evidently, every boss, who strives to manage his business successfully and wants to receive high profit, devotes much time to the selection process to find the right employees for his company. Nowadays it is not easy to find the appropriate employee, because people want to earn much but work less, so selection process can enable the boss to find the very people, who can devote their lives for the common profit of the company.
Male genital morphology in insects and arachnids is characterized by static hypoallometry and low intrapopulational levels of phenotypic variation relative to other male traits. The one-size-fits-all model of genital evolution attributes these patterns to stabilizing sexual selection. This model relies on the assumption that the observed patterns of variation and allometry reflect the form of sexual selection acting these traits. We test this by examining the patterns of scaling and trait variation for a set of genitalic and somatic morphological traits in male water striders Aquarius remigis. This suite of traits is of particular interest because previous work has shown that the genitalic traits are under strong directional selection whereas the somatic traits are under either weak directional or stabilizing selection.
Host—parasite coevolution is a special case of coevolution , the reciprocal adaptive genetic change of a host and a parasite through reciprocal selective pressures. It is characterized by reciprocal genetic change and thus changes in allele frequencies within populations. These are determined by three main types of selection dynamics: negative frequency-dependent selection when a rare allele has a selective advantage; overdominance caused by heterozygote advantage ; and directional selective sweeps near an advantageous mutation. Theories of host—parasite coevolution include the geographic mosaic theory, which assumes a selection mosaic, coevolutionary hotspots, and geographic mixing; the Red Queen hypothesis , which proposes that parasitism favours sexual reproduction in the host; and an evolutionary trade-off between transmission and virulence, since if the parasite kills its host too quickly, the parasite will not be able to reproduce.