4: Evolution
- Page ID
- 176805
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Introduction
Life on Earth is not static, it is always changing. Evolution is the process of how populations of living species change over many generations. This is the cause of the wide variety of life we see today! In this chapter, you will learn about the history of the discovery of the process of evolution, the processes that cause these genetic changes, and the evidence that supports it. You will also explore how organisms adapt to their environments, how new species form, and how all living things are connected. Understanding evolution helps us explain both the similarities and differences among living things and why life changes over time. Evolution is the unifying concept for understanding biology.
- 4.1: Discovering How Populations Change
- This page explores the principles of evolution, highlighting natural selection and its historical context with contributions from Lamarck and Hutton. It covers Darwin and Wallace's independent theories, supported by the Grants' finch study, showcasing adaptive traits like beak size. The page also delves into genetic variations, divergent and convergent evolution, and the Modern Synthesis, which links genetics and natural selection.
- 4.2: Adaptive Evolution
- This page explores mechanisms of natural selection and its effects on population variation, highlighting adaptive evolution and relative fitness. It details types of selection: stabilizing, directional, and diversifying, each influencing traits differently based on environmental factors. Real-world examples demonstrate the ongoing adaptation of populations, showcasing the complexity of evolutionary processes.
- 4.3: Mechanisms of Evolution
- This page discusses the Hardy-Weinberg equilibrium, which asserts that allele frequencies stay constant in the absence of natural selection, mutation, genetic drift, or gene flow. It explains how natural selection promotes advantageous alleles, mutations add genetic variation, and genetic drift notably influences small populations.
- 4.4: Evidence of Evolution
- This page explores evidence for evolution through fossils, anatomy, embryology, biogeography, and molecular biology. Fossils document the progression of species, such as horse evolution. Homologous and vestigial structures in anatomy suggest common ancestry and evolutionary remnants, respectively. Biogeography illustrates species distribution linked to continental shifts.
- 4.5: Speciation (for reference)
- This page explores the biological definition of species and speciation processes, highlighting allopatric and sympatric speciation. Allopatric speciation occurs due to geographic isolation, while sympatric speciation can result from mechanisms like polyploidy. Reproductive isolation, both prezygotic and postzygotic, is crucial for maintaining species boundaries.
Thumbnail Darwin's finches By John Gould (14.Sep.1804 - 3.Feb.1881) - From Voyage of the Beagle. Public Domain.