Course: Evolution, Ecology and Behavior with Stephen C. Stearns Dnatube

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Lec 1 - The Nature of Evolution: Selecti ...

"Lec 1 - The Nature of Evolution: Selection, Inheritance, and History" Principles of Evolution, Ecology and Behavior (EEB 122) The lecture presents an overview of evolutionary biology and its two major components, microevolution and macroevolution. The idea of evolution goes back before Darwin, although Darwin thought of natural selection. Evolution is driven by natural selection, the...
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Lec 2 - Basic Transmission Genetics

"Lec 2 - Basic Transmission Genetics" Principles of Evolution, Ecology and Behavior (EEB 122) Genetic transmission is the mechanism that drives evolution. DNA encodes all the information necessary to make an organism. Every organism's DNA is made of the same basic parts, arranged in different orders. DNA is divided into chromosomes, or groups of genes, which code for proteins. Asexually...
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Lec 3 - Adaptive Evolution: Natural Sele ...

"Lec 3 - Adaptive Evolution: Natural Selection" Principles of Evolution, Ecology and Behavior (EEB 122) Adaptive Evolution is driven by natural selection. Natural selection is not "survival of the fittest," but rather "reproduction of the fittest." Evolution can occur at many different speeds based on the strength of the selection driving it. These types of selection can result in...
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Lec 4 - Neutral Evolution: Genetic Drift

"Lec 4 - Neutral Evolution: Genetic Drift" Principles of Evolution, Ecology and Behavior (EEB 122) Neutral evolution occurs when genes do not experience natural selection because they have no effect on reproductive success. Neutrality arises when mutations in an organism's genotype cause no change in its phenotype, or when changes in the genotype bring about changes in the phenotype that do...
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Lec 5 - How Selection Changes the Geneti ...

"Lec 5 - How Selection Changes the Genetic Composition of Population" Principles of Evolution, Ecology and Behavior (EEB 122) Genetics controls evolution. There are four major genetic systems, which are combinations of sexual/asexual and haploid/diploid. In all genetic systems, adaptive genetic change tends to start out slow, accelerate in the middle, and occur slowly at the end. Asexual...
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Lec 6 - The Origin and Maintenance of Ge ...

"Lec 6 - The Origin and Maintenance of Genetic Variation" Principles of Evolution, Ecology and Behavior (EEB 122) Mutations are the origin of genetic diversity. Mutations introduce new traits, while selection eliminates most of the reproductively unsuccessful traits. Sexual recombination of alleles can also account for much of the genetic diversity in sexual species. In some instances,...
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Lec 7 - The Importance of Development in ...

"Lec 7 - The Importance of Development in Evolution" Principles of Evolution, Ecology and Behavior (EEB 122) Development is responsible for the complexity of multicellular organisms. It helps to map the genotype into the phenotype expressed by the organism. Development is responsible for ancient patterns among related organisms, and many structures important to development shared by many...
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Lec 8 - The Expression of Variation: Rea ...

"Lec 8 - The Expression of Variation: Reaction Norms" Principles of Evolution, Ecology and Behavior (EEB 122) Reaction norms depict the range of phenotypes a single genotype can produce, depending on the environment. Reaction norms must fit within an organism's phylogenetic constraints. They can differ for different individuals within a population, but some traits differ very little based on...
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Lec 9 - The Evolution of Sex

"Lec 9 - The Evolution of Sex" Principles of Evolution, Ecology and Behavior (EEB 122) There are several explanations for the evolution of sex and its continued prevalence. One is facilitating the spread of helpful mutations while hastening the removal of harmful ones. Another is expediting resistance against pathogens. Sex does have several costs compared to asex, such as only giving half...
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Lec 10 - Genomic Conflict

"Lec 10 - Genomic Conflict" Principles of Evolution, Ecology and Behavior (EEB 122) Genomic conflict arises when the interests of various genomic elements, such as chromosomes and cytoplasmic organelles, are not aligned. These conflicts arise in two situations: either when one unit is contained within another, as a mitochondrion is contained within a cell, or when inheritance is...
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Lec 11 - Life History Evolution

"Lec 11 - Life History Evolution" Principles of Evolution, Ecology and Behavior (EEB 122) Life history covers three main classes of traits in organisms: age and size at maturity, number and size of offspring, and lifespan and reproductive investment. Organisms must make tradeoffs among these traits that typically cause them to come to evolutionary equilibrium at intermediate values. Life...
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Lec 12 - Sex Allocation

"Lec 12 - Sex Allocation" Principles of Evolution, Ecology and Behavior (EEB 122) Sex allocation is an organism's decision on how much of its reproductive investment should be distributed to male and female functions and/or offspring. Under most conditions, the optimal ratio is 50:50, but that can change under certain circumstances. Sex allocation determines what sexes sequential...
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Lec 13 - Sexual Selection

"Lec 13 - Sexual Selection" Principles of Evolution, Ecology and Behavior (EEB 122) Sexual selection is a component of natural selection in which mating success is traded for survival. Natural selection is not necessarily survival of the fittest, but reproduction of the fittest. Sexual dimorphism is a product of sexual selection. In intersexual selection, a sex chooses a mate. In intrasexual...
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Lec 14 - Species and Speciation

"Lec 14 - Species and Speciation" Principles of Evolution, Ecology and Behavior (EEB 122) Speciation is the process through which species diverge from each other and/or from a common ancestor. There are several definitions of species, most of which focus on reproductive isolation and/or phylogenetic similarities. This can cause some controversy. Speciation can result from geographical...
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Lec 15 - Phylogeny and Systematics

"Lec 15 - Phylogeny and Systematics" Principles of Evolution, Ecology and Behavior (EEB 122) The Tree of Life must be discovered through rigorous analysis. Genetic information is crucial because appearances can be deceiving, and species that look similar can prove to be genetically very dissimilar and not share recent common ancestors. Two criteria, used to determine what the "correct" Tree...
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Lec 16 - Comparative Methods: Trees, Map ...

"Lec 16 - Comparative Methods: Trees, Maps, and Traits" Principles of Evolution, Ecology and Behavior (EEB 122) We can use methods of genetic analysis to connect phylogenic information to geographical histories. Human migration has left genetic traces on every continent, and allows us to trace our roots back to Africa. Molecular genetic methods allow us to determine whether or not trait...
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Lec 17 - Key Events in Evolution

"Lec 17 - Key Events in Evolution" Principles of Evolution, Ecology and Behavior (EEB 122) The history of life and evolution has been characterized by several key events. These events can be grouped as new hierarchal levels of selection coming into play, as biological units coming together in symbiosis and specialization, or in a number of other ways. Other important events are situations of...
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Lec 18 - Major Events in the Geological ...

"Lec 18 - Major Events in the Geological Theatre" Principles of Evolution, Ecology and Behavior (EEB 122) Geology and climate have shaped the development of life tremendously. This has occurred in the form of processes such as the oxygenation of the atmosphere, mass extinctions, tectonic drift, and disasters such as floods and volcanic eruptions. Life, particularly bacteria, has also been...
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Lec 19 - The Fossil Record and Life's Hi ...

"Lec 19 - The Fossil Record and Life's History" Principles of Evolution, Ecology and Behavior (EEB 122) The fossil record holds a lot of evolutionary information that can't be seen on shorter time scales, although the more recent fossil record is more complete. Among other things, the fossil record demonstrates that extinctions can open up ecological space for new speciation and radiation,...
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Lec 20 - Coevolution

"Lec 20 - Coevolution" Principles of Evolution, Ecology and Behavior (EEB 122) Coevolution happens at many levels, not just the level of species. Organelles such as mitochondria and chloroplasts serve as good intracellular examples. Other living things make up a crucial component of an organism's environment. Coevolution can occur in helpful ways (symbiosis) and in harmful ways (parasitism)....
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Lec 21 - Evolutionary Medicine

"Lec 21 - Evolutionary Medicine" Principles of Evolution, Ecology and Behavior (EEB 122) Evolution plays an important though underutilized role in medicine. Evolution guides how our bodies respond to various treatments, how pathogens will respond to treatments, and how pathogens' responses will change over time. Pathogens oftentimes will evolve to an intermediate level of virulence where...
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Lec 22 - The Impact of Evolutionary Thou ...

"Lec 22 - The Impact of Evolutionary Thought on the Social Sciences" Principles of Evolution, Ecology and Behavior (EEB 122) There is a distinct possibility that humans are currently part way through an evolutionary transition between individuals and groups. The conflict between these two units of selection and levels of organization, between biology and culture, may explain some of the...
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Lec 23 - The Logic of Science

"Lec 23 - The Logic of Science" Principles of Evolution, Ecology and Behavior (EEB 122) While there are many differences between modern science and philosophy, there are still a number of lessons in modes of thought that scientists can take from philosophy. Scientists' ideas about the nature of science have evolved over time, leading to new ideas about falsifiability, creativity,...
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Lec 24 - Climate and the Distribution of ...

"Lec 24 - Climate and the Distribution of Life on Earth" Principles of Evolution, Ecology and Behavior (EEB 122) This lecture provides an overview of the physical aspects of earth's biomes. Temperature, water, latitude, and altitude all come into play. Regions with similar levels of these climatic features tend to have similar life-forms living there. These same climatic features can also...
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Lec 25 - Interactions with the Physical ...

"Lec 25 - Interactions with the Physical Environment" Principles of Evolution, Ecology and Behavior (EEB 122) Every species on earth has an environmental range in which it can live. Usually it flourishes in the central portion of this range. Organisms contain a host of adaptations that allow them to manipulate their environments to remain within their preferred range. Plants and animals...
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Lec 26 - Population Growth: Density Effects

"Lec 26 - Population Growth: Density Effects" Principles of Evolution, Ecology and Behavior (EEB 122) The growth of populations is held in check by several factors. These can include predators, food and other resources, and density. Population density affects growth rate by determining how likely is it that an organism will interact with a member of its own species compared to an organism of...
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Lec 27 - Interspecific Competition

"Lec 27 - Interspecific Competition" Principles of Evolution, Ecology and Behavior (EEB 122) Competition among species, or interspecific competition, can have an even greater effect on selection than competition within species (intraspecific competition). This is often the case in lower density populations. Different species can have positive, neutral, or negative effects on each other's...
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Lec 28 - Ecological Communities

"Lec 28 - Ecological Communities" Principles of Evolution, Ecology and Behavior (EEB 122) The idea of ecological communities has changed tremendously over the past forty years. The classical view stated that there were so many different species because evolution packed them tightly into the available niches. The modern view emphasizes the idea of trophic cascades, or top-down control in food...
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Lec 29 - Island Biogeography and Invasiv ...

"Lec 29 - Island Biogeography and Invasive Species" Principles of Evolution, Ecology and Behavior (EEB 122) Geography is very important in ecology. Two major systems have been designed to model this, island biogeography and metapopulations. The idea of metapopulations is more recent, and has emerged as the dominant theory. Metapopulations are populations in multiple neighboring areas. The...
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Lec 30 - Energy and Matter in Ecosystems

"Lec 30 - Energy and Matter in Ecosystems" Principles of Evolution, Ecology and Behavior (EEB 122) The movement of matter and energy around the planet is very important, and its study draws on geology, and meterology in addition to chemistry. Energy tends to flow upwards from plantlike producers to herbivores to carnivores before being decomposed by detritovores and cycling back into energy...
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Lec 31 - Why So Many Species? The Factor ...

"Lec 31 - Why So Many Species? The Factors Affecting Biodiversity" Principles of Evolution, Ecology and Behavior (EEB 122) One can look at biodiversity from several perspectives. An ecological point of view tries to determine how necessary diversity is for an ecosystem to function. An economic point of view tries to capture the value of the "services" nature provides for mankind. An...
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Lec 32 - Economic Decisions for the Fora ...

"Lec 32 - Economic Decisions for the Foraging Individual" Principles of Evolution, Ecology and Behavior (EEB 122) There are several ways to examine the behaviors of organisms when they forage or hunt for food or mates. These behaviors become more complex in higher organisms, such as primates and whales, which can hunt in groups. Foragers and hunters have been shown to examine the marginal...
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Lec 33 - Evolutionary Game Theory: Fight ...

"Lec 33 - Evolutionary Game Theory: Fighting and Contests" Principles of Evolution, Ecology and Behavior (EEB 122) The economic concept of game theory can be readily applied to evolution and behavior. By analyzing encounters between organisms as a mathematical "game," important information such as fitness payoffs and the proportions of "strategies" played by each group within a population...
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Lec 34 - Mating Systems and Parental Care

"Lec 34 - Mating Systems and Parental Care" Principles of Evolution, Ecology and Behavior (EEB 122) Mating systems and parental care vary tremendously from species to species. Every species differs in how it protects its young from predators and provides its young with food, if it does so at all. The physical environment as well as behavioral dynamics in intraspecies relationships all...
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Lec 35 - Alternative Breeding Strategies

"Lec 35 - Alternative Breeding Strategies Principles of Evolution, Ecology and Behavior (EEB 122) Breeding strategies differ both among males and females of the same species as well as among different species. The difference in breeding strategies among members of the same species can usually be linked to frequency dependence. If the species is at evolutionary equilibrium, the relative...
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Lec Last - Selfishness and Altruism

"Lec Last - Selfishness and Altruism" Principles of Evolution, Ecology and Behavior (EEB 122) Originally, altruism and self-sacrifice were thought to be incompatible with natural selection, even by Darwin. Now we have several explanations for how altruism can increase an individual's fitness. One is kin selection, or the idea that helping relatives can help increase one's genes in the...

Evolution, Ecology and Behavior with Stephen C. Stearns


Source of these courses is Yale 
This course presents the principles of evolution, ecology, and behavior for students beginning their study of biology and of the environment. It discusses major ideas and results in a manner accessible to all Yale College undergraduates. Recent advances have energized these fields with results that have implications well beyond their boundaries: ideas, mechanisms, and processes that should form part of the toolkit of all biologists and educated citizens.
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COURSE NAME: Evolution, Ecology and Behavior with Stephen C. Stearns

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