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The McDonald–Kreitman test [1] is a statistical test often used by evolutionary and population biologists to detect and measure the amount of adaptive evolution within a species by determining whether adaptive evolution has occurred, and the proportion of substitutions that resulted from positive selection (also known as directional selection).
Direct reciprocity was proposed by Robert Trivers as a mechanism for the evolution of cooperation. [1] If there are repeated encounters between the same two players in an evolutionary game in which each of them can choose either to "cooperate" or "defect", then a strategy of mutual cooperation may be favoured even if it pays each player, in the short term, to defect when the other cooperates.
Therefore, parents allot equal investment of effort in both sexes. More generally, the expected sex ratio is the ratio of the allotted investment between the sexes, and is sometimes referred to as Fisherian sex ratios. However, there are many examples of organisms that do not demonstrate the expected 1:1 ratio or the equivalent investment ratio.
Fisher's principle is an evolutionary model that explains why the sex ratio of most species that produce offspring through sexual reproduction is approximately 1:1 between males and females. A. W. F. Edwards has remarked that it is "probably the most celebrated argument in evolutionary biology". [1]
In their experiment, Luria and Delbrück inoculated a small number of bacteria (Escherichia coli) into separate culture tubes. After a period of growth, they plated equal volumes of these separate cultures onto agar containing the T1 phage (virus). If resistance to the virus in bacteria were caused by an induced activation in bacteria i.e. if ...
Mesocosm experiments also tend to include replication of different treatment levels. Manipulating something can give an idea as to what to expect if something were to occur in that ecosystem or environment. [2] For indoor mesocosms, growth chambers grant greater control over the experiment. [2]
The Trivers–Willard hypothesis has been applied to resource differences among individuals in a society as well as to resource differences among societies.Investigations in humans pose a number of practical and methodological difficulties, [6] but while a 2007 review of previous research found that empirical evidence for the hypothesis was mixed, the author noted that it received greater ...
These are direct phenotypic benefits, sensory bias, the Fisherian runaway hypothesis, indicator traits and genetic compatibility. In the majority of systems where mate choice exists, one sex tends to be competitive with their same-sex members [ 4 ] and the other sex is choosy (meaning they are selective when it comes to picking individuals to ...