AGRC1020 Lecture Notes - Lecture 6: George Gaylord Simpson, Gregor Mendel, Agrostis Capillaris
6 Aug 2018
School
Department
Course
Professor
Document Summary
One common misconception about evolution is that organisms evolve, in a darwinian sense, during their lifetimes. Each individual"s combination of inherited traits affects its survival and its reproductive success relative to other individuals in the population. However, the evolutionary impact of natural selection is only apparent in the changes in a population of organisms over time. It is the population, not the individual, that evolves. Consider the example of bent grass (agrostis tenuis) growing on the tailings of an abandoned mine. These tailings are rich in toxic heavy metals. While many bent grass seeds land on the mine tailings each year, the only plants that germinate, grow, and reproduce are those that possess genes enabling them to tolerate metallic soils. Individual plants do not evolve to become more metal-tolerant during their lifetimes. Darwin proposed a mechanism for change in species over time.
