Course

Evolution, Ecology and Behavior

Yale University

This course provides a comprehensive introduction to the principles of evolution, ecology, and behavior, tailored for students beginning their studies in biology and environmental science.

The course covers:

  • Key concepts in evolutionary biology, including selection and genetic transmission.
  • Recent advances in the fields that have broad implications beyond biology.
  • The importance of understanding these principles as part of a well-rounded education.

By the end of this course, students will possess a toolkit of ideas, mechanisms, and processes that are fundamental to all biologists and informed citizens.

Course Lectures
  • This module provides a comprehensive overview of evolutionary biology, focusing on both microevolution and macroevolution. It highlights:

    • The historical context of evolutionary theory, predating Darwin.
    • The mechanisms of evolution, including natural selection and random drift.
    • The timeline of life on Earth, tracing back approximately 3.7 billion years.

    Students will learn how these components interact to shape the diversity of life.

  • Basic Transmission Genetics
    Stephen C Stearns

    This module delves into the mechanisms of genetic transmission, which is crucial for understanding evolution. Key points include:

    • The structure and function of DNA as the coding material for organisms.
    • The role of chromosomes and genes in encoding proteins.
    • The processes of asexual reproduction through mitosis and sexual reproduction through meiosis.

    Students will also explore the importance of RNA in these processes and how genetic transmission influences evolutionary dynamics.

  • This module focuses on adaptive evolution driven by natural selection. Students will learn about:

    • The concept of "reproduction of the fittest" versus "survival of the fittest."
    • The different speeds of evolutionary change based on selection strength.
    • The types of natural selection: directional, stabilizing, and disruptive.

    Additionally, students will examine the roles of frequency-dependent selection and sexual selection in shaping evolution.

  • This module examines neutral evolution, where genes do not undergo natural selection. Key topics include:

    • The concept of genetic drift and its role in evolution.
    • How mutations can lead to neutrality in genotype without phenotypic effects.
    • The use of neutral genes as molecular clocks for determining evolutionary relationships.

    Students will explore the implications of neutrality in the phylogenetic tree of life.

  • This module discusses how selection alters the genetic composition of populations. Key aspects include:

    • The four major genetic systems influenced by selection.
    • The dynamics of adaptive genetic change over time.
    • The factors affecting gene frequency changes in large populations.

    Students will gain insights into how genetics influences evolutionary processes and population dynamics.

  • This module focuses on the origin and maintenance of genetic variation within populations. It covers:

    • The role of mutations in introducing new traits.
    • How selection eliminates less advantageous traits over time.
    • The impact of sexual recombination on genetic diversity.

    Additionally, students will explore how population size can influence genetic diversity and rates of evolution.

  • This module addresses the significance of development in evolution. Key topics include:

    • The mapping of genotype to phenotype in multicellular organisms.
    • Ancient developmental patterns shared among related species.
    • The combinatorial nature of development, allowing diverse expressions of genetic information.

    Students will learn how developmental processes influence evolutionary outcomes.

  • This module explores reaction norms, illustrating how environmental factors influence phenotypic expression. Students will focus on:

    • The range of phenotypes produced by a single genotype across various environments.
    • The phylogenetic constraints that shape reaction norms.
    • Variability in traits among individuals within populations.

    Understanding reaction norms is crucial for grasping how organisms adapt to their environments.

  • The Evolution of Sex
    Stephen C Stearns

    This module investigates the evolution of sex, discussing its advantages and challenges. Key topics include:

    • Theories explaining the prevalence of sexual reproduction.
    • Benefits of sex, such as spreading advantageous mutations and facilitating pathogen resistance.
    • Costs associated with sexual reproduction, including mate finding and increased predation risk.

    Students will analyze why sex remains a dominant reproductive strategy despite its costs.

  • Genomic Conflict
    Stephen C Stearns

    This module focuses on genomic conflict, where different genomic elements have competing interests. Key points include:

    • Situations leading to genomic conflict, such as asymmetrical inheritance.
    • Examples of conflict within cells and between organisms.
    • Strategies developed to mitigate genomic conflict in sexual species.

    Students will understand the implications of genomic conflict for evolutionary biology.

  • Life History Evolution
    Stephen C Stearns

    This module covers life history evolution, focusing on the trade-offs organisms face. Key concepts include:

    • Three main classes of life history traits: maturity, offspring, and lifespan.
    • Trade-offs that arise from ecological pressures.
    • How life history traits contribute to evolutionary equilibria.

    Students will explore how these traits reflect adaptations to ecological challenges.

  • Sex Allocation
    Stephen C Stearns

    This module discusses sex allocation, the reproductive investment decisions of organisms. Key points include:

    • Optimal sex ratios in various conditions.
    • Sequential and simultaneous hermaphroditism in different species.
    • Environmental influences on sex allocation strategies.

    Students will analyze how sex allocation affects reproductive success and population dynamics.

  • Sexual Selection
    Stephen C Stearns

    This module focuses on sexual selection as a key component of natural selection. Topics include:

    • The trade-off between mating success and survival.
    • Sexual dimorphism and its evolutionary significance.
    • Intersexual and intrasexual selection mechanisms.

    Students will learn how sexual selection shapes behaviors and traits in different species.

  • Species and Speciation
    Stephen C Stearns

    This module covers species and the process of speciation. Key concepts include:

    • Definitions of species based on reproductive isolation and phylogenetic similarities.
    • The mechanisms driving speciation, including geographical and ecological factors.
    • The stages of speciation from populations to distinct species.

    Students will gain insights into biodiversity and the complexity of species formation.

  • Phylogeny and Systematics
    Stephen C Stearns

    This module examines phylogeny and systematics, focusing on constructing the Tree of Life. Key topics include:

    • The importance of genetic information in determining relationships among species.
    • Criteria for constructing phylogenetic trees: simplicity and probability.
    • How morphological similarities can sometimes mislead phylogenetic analysis.

    Students will learn to critically assess the evolutionary relationships among organisms.

  • This module discusses comparative methods in analyzing trees, maps, and traits. Key aspects include:

    • Connecting phylogenetic information to geographical histories.
    • Using molecular genetics to trace human migration and roots.
    • Determining ancestral trait states and their implications for biological understanding.

    Students will appreciate how comparative methods enhance our understanding of evolution and adaptation.

  • Key Events in Evolution
    Stephen C Stearns

    This module explores key events in evolution that have shaped life on Earth. Topics include:

    • New hierarchical levels of selection and their impact.
    • Symbiosis and specialization in evolutionary history.
    • Conflict resolution and information transmission in biological systems.

    Students will understand how these events frame our understanding of evolution.

  • This module focuses on major geological events and their impact on evolution. Key aspects include:

    • The oxygenation of the atmosphere and its effects on life.
    • Mass extinctions and their role in shaping biodiversity.
    • Tectonic drift and geological disasters' influence on evolutionary trajectories.

    Students will learn to connect geological processes with biological evolution.

  • This module discusses the fossil record and its significance in understanding life's history. Key topics include:

    • The fossil record's role in revealing long-term evolutionary patterns.
    • How extinctions create ecological opportunities for new species.
    • The trends of life forms evolving from small beginnings to larger sizes.

    Students will appreciate how fossils contribute to our understanding of evolution.

  • Coevolution
    Stephen C Stearns

    This module investigates coevolution and its implications across different biological levels. Key points include:

    • Examples of coevolution at the organelle level, such as mitochondria.
    • The role of coevolution in shaping interactions among species.
    • Factors influencing coevolution, including interaction frequency.

    Students will learn how coevolution affects biodiversity and ecological dynamics.

  • Evolutionary Medicine
    Stephen C Stearns

    This module covers the role of evolution in medicine, emphasizing its implications for health. Key topics include:

    • The influence of evolutionary principles on human physiology.
    • Pathogen evolution and its impact on treatment efficacy.
    • The balance between virulence and transmission in pathogens.

    Students will gain insights into how evolutionary thought can inform medical practices.

  • This module explores the impact of evolutionary thought on social sciences. Key points include:

    • The potential for an evolutionary transition in human organization.
    • Conflicts between individual and group selection.
    • Examples of altruism and selfishness as evolutionary traits.

    Students will analyze how evolutionary perspectives can explain modern societal tensions.

  • The Logic of Science
    Stephen C Stearns

    This module discusses the logic of science, drawing connections between science and philosophy. Key topics include:

    • Evolution of ideas about the nature of science over time.
    • Lessons from philosophy regarding creativity and falsifiability.
    • The boundaries and limits of scientific inquiry.

    Students will reflect on the philosophical underpinnings of scientific thought.

  • This module examines climate's role in shaping the distribution of life on Earth. Key topics include:

    • The influence of temperature, water, latitude, and altitude on biomes.
    • Similar climatic conditions leading to analogous life forms.
    • How large-scale weather patterns affect ecosystems and habitats.

    Students will understand the critical relationship between climate and biodiversity.

  • This module investigates interactions between species and their physical environments. Key points include:

    • The concept of environmental ranges for species.
    • Adaptations species employ to thrive within their preferred ranges.
    • Differences in adaptations between plants and animals.

    Students will explore how species manipulate their environments to optimize survival.

  • This module discusses population growth and the effects of density on growth rates. Key topics include:

    • Factors limiting population growth, such as predators and resources.
    • The role of population density in determining interaction probabilities.
    • Mathematics of population growth using logarithmic and exponential models.

    Students will analyze how density-dependent factors influence population dynamics.

  • Interspecific Competition
    Stephen C Stearns

    This module examines interspecific competition and its effects on selection. Key points include:

    • The impact of competition among different species versus within species.
    • Positive, neutral, and negative effects of species interactions on fitness.
    • How competition shapes evolutionary dynamics and ecological communities.

    Students will explore the complexities of interspecific interactions and their evolutionary implications.

  • Ecological Communities
    Stephen C Stearns

    This module provides an overview of ecological communities and their dynamics. Key aspects include:

    • The evolution of ecological community concepts over the past forty years.
    • The classical view of niche packing versus modern views emphasizing trophic cascades.
    • The importance of predation and food webs in ecosystem functioning.

    Students will gain insights into the complexities of ecological interactions and community structure.

  • This module focuses on island biogeography and the impact of invasive species. Key points include:

    • The significance of geographical features in shaping species distributions.
    • Theories of island biogeography and metapopulation dynamics.
    • The implications of metapopulations for conservation and disease studies.

    Students will analyze how geography influences biodiversity and species interactions.

  • This module examines energy and matter flows in ecosystems. Key topics include:

    • The movement of energy from producers to consumers and decomposers.
    • The cycles of essential compounds, such as carbon and nitrogen.
    • The importance of understanding energy flow for ecosystem health.

    Students will explore the interconnectedness of energy and matter in sustaining life.

  • This module investigates factors affecting biodiversity, addressing ecological, economic, evolutionary, and personal perspectives. Key points include:

    • Ecological viewpoints on the necessity of diversity for ecosystem function.
    • Economic assessments of nature's services to humanity.
    • Evolutionary insights into human dominance and biodiversity.
    • Personal values and emotional connections to biodiversity.

    Students will gain a multifaceted understanding of biodiversity's value and importance.

  • This module focuses on economic decisions made by foraging individuals. Topics include:

    • Behaviors of organisms while foraging for food and mates.
    • Complexities in foraging strategies among higher organisms.
    • The role of marginal cost and benefit analyses in foraging behavior.

    Students will analyze how organisms optimize foraging decisions based on environmental conditions.

  • This module applies evolutionary game theory to the study of fighting and contests. Key concepts include:

    • Analyzing encounters as mathematical games to derive key fitness payoffs.
    • The concept of strategies within populations and their proportions.
    • The usefulness and limitations of game theory models in understanding behavior.

    Students will explore how game theory provides insights into evolutionary dynamics and animal behavior.

  • This module explores mating systems and parental care across species. Key points include:

    • Diversity in parental care behaviors and protection of offspring.
    • How environmental and behavioral dynamics shape parental strategies.
    • The influence of mating systems on the process of parental care.

    Students will analyze how reproductive strategies affect offspring survival and species dynamics.

  • This module discusses alternative breeding strategies among and within species. Key topics include:

    • Differences in breeding strategies among males and females of the same species.
    • Frequency dependence in breeding strategies at evolutionary equilibrium.
    • Variability in strategies observed at the gamete and organism level.

    Students will explore how alternative strategies affect fitness and reproductive success.

  • Selfishness and Altruism
    Stephen C Stearns

    This module examines selfishness and altruism in the context of natural selection. Key points include:

    • The historical view of altruism's compatibility with natural selection.
    • Current explanations for how altruism can enhance individual fitness.
    • Concepts of kin selection and ecological constraints influencing altruistic behaviors.

    Students will analyze the evolutionary significance of altruism and its role in social dynamics.