A stroke can result in a number of visual problems, including visual neglect, decreased visual acuity, diplopia (double-vision), squint, and homonymous hemianopsia (visual field defects).
Natural Selection. Natural selection is the process by which individuals with characteristics that are advantageous for reproduction in a specific environment leave more offspring in the next generation, thereby increasing the proportion of their genes in the population gene pool over time.
Describe the theory of evolution by natural selection. Natural selection occurs when environmental conditions select for certain advantageous traits. Because traits are heritable, the traits of those who successfully reproduced are more common in the next generation. And in this way, nature selects for these traits. Evolution by natural selection is thus the change in the frequency of different alleles for a trait through time. Over time, natural selection can allow species to adapt to changing environmental conditions and diverge from one another, leading to the great diversity of form and function of organisms we observe today.