Chapter 23 - The evolution of populations. This chapter presents the following content: The modern evolutionary synthesis integrated Darwinian selection and Mendelian inheritance, a population’s gene pool is defined by its allele frequencies, the Hardy-Weinberg theorem describes a nonevolving population. | CHAPTER 23 The Evolution of Populations Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section A: Population Genetics 1. The modern evolutionary synthesis integrated Darwinian selection and Mendelian inheritance 2. A population’s gene pool is defined by its allele frequencies 3. The Hardy-Weinberg theorem describes a nonevolving population One obstacle to understanding evolution is the common misconception that organisms evolve, in a Darwinian sense, in their lifetimes. Natural selection does act on individuals by impacting their chances of survival and their reproductive success. However, the evolutionary impact of natural selection is only apparent in tracking how a population of organisms changes over time. It is the population, not its individual, that evolves. Introduction Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Evolution on the scale of populations, called microevolution, is defined as a change in the allele frequencies in a population. For example, the bent grass (Argrostis tenuis) in this photo is growing on the tailings of an abandoned mine, rich in toxic heavy metals. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. While many seeds land on the mine tailings each year, the only plants that germinate, grow, and reproduce are those that had already inherited genes enabling them to tolerate metallic soils. Individual plants do not evolve to become more metal-tolerant during their lifetimes. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings The Origin of Species convinced most biologists that species are the products of evolution, but acceptance of natural selection as the main mechanism of evolution was more difficult. What was missing in Darwin’s explanation was an understanding of inheritance that could explain how chance variations arise in a population while also accounting for the precise transmission of these variations from parents | CHAPTER 23 The Evolution of Populations Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Section A: Population Genetics 1. The modern evolutionary synthesis integrated Darwinian selection and Mendelian inheritance 2. A population’s gene pool is defined by its allele frequencies 3. The Hardy-Weinberg theorem describes a nonevolving population One obstacle to understanding evolution is the common misconception that organisms evolve, in a Darwinian sense, in their lifetimes. Natural selection does act on individuals by impacting their chances of survival and their reproductive success. However, the evolutionary impact of natural selection is only apparent in tracking how a population of organisms changes over time. It is the population, not its individual, that evolves. Introduction Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Evolution on the scale of populations, called microevolution, is defined as a change in the allele .
