Exam 3 Study Guide/List of Topics (Chapters 15-21)

Chapter 15: Natural Selection

People:

Herbert Spenser / (1820-1903) / British / · Principles of Biology (1864)- coined the phrase “survival of the fittest”
· Most respected, influential and popular philosopher of his day and a partial advocate for Darwinism
· Take on evolution was more Lamarckian and Orthogenetic
· believed evolution had a higher purpose and a final equilibrium, related to the social development of humanity, to the “perfect man in the perfect society”
Founders of the Modern Synthesis / · Verne Grant (1917-2007)- botanist
· G. Ledyard Stebbins, Jr. (1906-2000)- botanist and geneticist
· Ernst Mayr (1905-2005) Ornithologist & Taxonomist
· G.G. Simpson (1902-1984)- Vertebrate Paleontologist
· Bernhard Rensch (1900-1990)- Ornithologist and ethologist
· Edwin Brisco “Henry” Ford (1901-1988)- invented ecological genetics
· Sergei Sergeevich Chetverikov (1880-1958)- geneticist whose work (1920s) influenced Haldane, Dobzhansky and others
Johann Friedrich Theodor “Fritz” Müller / (1821-1897) / German / · Studied aposematic colors in bees, mimicry in bees and butterflies, termite biology, orchid fertilization, climbing plants, and general tropical biology
· Für Darwin (Facts and Arguments for Darwin) (1864)
· Trained as a doctor in Germany but immigrated to Brazil in 1852 where he became a naturalist and scientist
Henry Walter Bates / (1825-1892) / English / · spent 14 years in the Amazon basin collecting and studying
· discovered defensive mimicry among rainforest butterflies
· The Naturalist on the River Amazons (1863)
·
Sergei Sergeevich Chetverikov / (1880-1958) / Russian / · geneticist whose work (1920s) influenced Haldane, Dobzhansky and others who founded the Modern Synthesis
Julian Huxley / (1887-1975) / British / · Thomas Henry Huxley’s grandson
· Coined the terms: clade, grade, cline, ethnic group, ritualized behaviors
· evolutionary biologist, science popularize, ornithologist, ethologist, humanist, conservationist, advocate for eugenics
Sewall Wright / (1889-1988) / American / · Developed the mathematical framework for understanding the genetic consequences of migration, effective population size, population subdivision
· Conceived of the concept of adaptive landscapes
· Evolution and the Genetics of Populations: Genetics and Biometric Foundations (1968-1978)
Sir Ronald A. Fisher / (1890-1962) / English / · World class statistician and a founder of population genetics
· The Genetical Theory of Natural Selection (1930)
· United Mendelian population genetics with the inheritance of continuous traits
· Advocated for eugenics
J.B.S. Haldane / (1892-1964) / British / · a founder of population genetics
· developed the mathematical theory of allele frequency change under selection
· The Causes of Evolution (1932)
· First biologist to qnaitify reproductive fitness
Robert Mertens / (1894-1975) / German / · Herpetologist whose name was given to a rare mimicry system in which a deadly prey species mimics a less dangerous species
· If there is some other species that is harmful but not deadly as well as aposematic, the predator may learn to recognize its particular warning colors and avoid such animals
· a deadly species will then profit by mimicking the less dangerous aposematic organism, if this results in fewer attacks than camouflage would
Theodosius Dobzhansky / (1900-1975) / American (Ukrainian born) / · who was one of the founders of the Modern Synthesis
· Genetics and the Origin of Species (1937)
· Defined evolution as “a change in the frequency of an allele within a gene pool”
· Origins of the Modern Synthesis
Bernhard Rensch / (1900-1990) / German / · Ornithologist and ethologist who was one of the founders of the Modern Synthesis
· Wrote Evolution above the Species Level (1947) which discussed how the evolutionary mechanisms that drove speciation could also explain the differences between higher taxa
· proposed what is now called Rensch's rule in 1950. It is an allometric law about the relationship between sexual size dimorphism (SSD) and which sex is larger. It observes that across species size dimorphism increases with increasing body size when the male is the larger sex, and decreases with increasing average body size when the female is the larger sex
Edwin Brisco “Henry” Ford / (1901-1988) / British / · zoologist and geneticist who was one of the founders of the Modern Synthesis
· invented ecological genetics
· was the first to describe and define genetic polymorphism
G. Ledyard Stebbins, Jr. / (1906-2000) / American / · botanist and geneticist who was one of the founders of the Modern Synthesis
· wrote Variation and Evolution in Plants (1950), which combined genetics and Darwin's theory of natural selection to describe plant speciation
· proposed that a high degree of genetic variability was necessary for major evolutionary advances, that because of slow mutation rates, genetic recombination was the most likely source of this variation, and that variation could be maximized though hybridization
V.C. Wynne-Edwards / (1906-1997) / English / · proposed that social behaviors act to keep social species from exceeding the carrying capacity of their environments; that social behaviors evolve to limit reproduction or fecundity
· proposed this hypothesis in his book Animal Dispersion in Relation to Social Behavior (1962) and continued in Evolution Through Group Selection (1986)
James F. Crow / (1916-2012) / American / · Contributed to the development of the neutral theory
Verne Grant / (1917-2007) / American / · Botanist who was one of the founders of the Modern Synthesis
· wrote The Origins of Adaptations (1963) which theorized about genetic drift, modes of speciation, natural selection and population genetics
John Maynard Smith / (1920-2004) / British / · one of the premiere evolutionary theorists of the 20th century, as well as one of the most mathematically inclined, was one of the first to investigate the details of the cost-benefit analysis for sexual versus asexual reproduction
· Coined the term “kin selection”
Motoo Kimura / (1924-1994) / Japanese / · Geneticist; advocated for the Neutral Theory
· (1983) The neural theory of molecular evolution
· By extrapolating backward from comparative amino acid secuqnces to the common ancestor of the two, using fossil evidence, Kimura estimated that a new neutral mutation must have been formed and achieved fixation every 2 years on average
Edward O. Wilson / (1929-present) / American / · (1975) The New Synthesis launched a new field of science which offered a way to solve the contradictions by placing humans within the tree of life
· E. O. Wilson, Sociobiology: The New Synthesis, 1975, launched a new field of science which offered a way to solve the contradictions by placing humans, as Darwin had, within the tree of life
· Animal behavior is shaped by natural selection
· Human behavior is determined in part by natural and sexual selection, but also by cultural forces which have no equivalent in animal societies
· Start with the constraints from the genotype and then see how environment can shape development from that foundation
W.D. Hamilton / (1936-2000) / British / · another of the world class evolutionary biologists of the post-WW II generation
· advocated for the importance of the gene as a unit of selection
· inclusive fitness theory
· investigated sex ratios and cost-benefit analyses, for the evolution of secual reproduction
· proponent of the Red Queen Hypothesis
Stephen Jay Gould / (1941-2002) / American / · Paleontologist, evolutionary biologist, science historian
· Contributed to evolutionary biology with the theory of punctuated equilibrium 1972
Richard Dawkins / (1941-present) / English / · Ethologist and evolutionary biologist
· The Selfish Gene (1976)
Niles Eldredge / (1943- present) / American / · Biologist and paleontologist
· Contributed to evolutionary biology with the theory of punctuated equilibrium 1972

Key Concepts:

· Darwinian Fitness

o Measurable mathematically; is a relative not an absolute measure

o The ability of an individual to survive and reproduce in its present environment

· Natural selection

o Not goal oriented

o Does not anticipate environmental changes

o Increases reproductive success in the current environment

o Always a generation behind any changes in the environment

o modifes designs, that is development, anatomy, physiology, ecology, and behavior in a random way

· Types of Natural Selection

o Normal distribution

§ Bell shaped curve

§ Can be controlled by multiple genes controlling polygenic phenotypic traits

o 1- Stabilizing selection

§ The extremes are selected against producing over subsequent generations a population with less variation, reflected in the tighter bell-shaped curve

§ examples: cliff swallows, selection for symmetry, form in animal species

o 2 - Disruptive selection

§ Individuals with intermediate features are selected against, eventually producing over the subsequent generations a divided result with two distinct phenotypes at the extremes with their own bell-shaped distributions

§ Examples: grove snails

o 3 – Directional selection

§ Selection acts against one extreme and favors the other

§ Example: peppered moths and pollution; artificial selection pressures; finches and drought

· Hardy Weinberg Principle

o (p+q)2 = p2 + 2pq + q2 = 1

§ p2 = individuals homozygous for first allele

§ 2pq = individuals heterozygous for the alleles

§ q2 = individuals homozygous for second allele

o Conditions:

o Selection coefficients

§ sp2(p2)+ s2pq(2pq) + sq2(q2)= 1

§ where S varies from 1.0 to 0.0

· Mating systems

o Promiscuous

§ There are no set breeding pairs, males and females mate with multiple partners

o Monogamous

§ One female and one male organism will mate for life

o Polygynous

§ One male may mate with several females

· Group Selesction

· Cost-Benefit Analysis for Sexual versus Asexual reproduction:

Sexual Reproduction / Asexual Reproduction
Advantages / · High Genetic Variability
· Facilitates adaptation
· “speeds” up evolution / · lower energy cost
· courtship is irrelevant
· greatest increase in fitness for each individual
Disadvantages / · higher energy cost
· courtship consumes time and resources
· usually sacrifices the fitness of one sex to the other / · Low genetic variability
· Adaptation to the environment is difficult
· “slows” evolution

· Kin selection: individuals will behave more altruistically and less competitively toward their relatives because they share a relatively high proportion of their genes; by helping a relative reproduce an individual passes its genes to the next generation

Social Systems: The Evolution of Cooperation

Advantages of sociality

– Reduced predation by improved detection or repulsion

– Improved foraging efficiency

– Improved territoriality against other groups of conspecifics

– Improved care of offspring

Disadvantages of sociality

– Increased competition within group for food, mates, nesting, etc.

– Increased risk of infection

– Increased exploitation of parental care by conspecifics

– Increased risk that conspecifics will kill ones progeny

Vocabulary:

Fitness: the level to which an organism is able to survive and reproduce successfully given their particular set of environmental conditions
Fundamental niche: the total range of environmental conditions that are suitable for existence
Realized niche: the part of the fundamental niche occupies by a species in relation to the influences of interspecific competition or predation/herbivory
Modern Synthesis: the classic Darwinian principles combined with the information provided by technological advances in genetics and other biological sciences
Population: a group of individuals belonging to the same species that live in the same region at the same time
Quantitative Characters: an inherited character that is expressed phenotypically in all degrees of variation between one often indefinite extreme and another; a character determined by polygenes
Allele frequencies: a measure of the relative occurance of an allele on a genetic locus in a population
Effective population size: the number of individuals in a population who contribute offspring to the next generation
Adaptive landscapes:
Panmictic population: a population where all individuals are potential reproductive partners
Reproductive fitness: the success of a given genotype based on its success in a population as a phenotype to increase its proportion in subsequent generations
Selection pressure: any forces acting upon the survival and reproduction of individuals in a population
Cryptic female choice: the ability of some female organisms to eliminate sperm/pollen from some male donors physiologically after insemination/pollination
Sperm competition: the displacement of sperm from previous mates by males of some species
Sexual dimorphism: distinct differences in morphology between the sexes of a species in addition to the difference between sexual organs
Sexual selection: Coined by Darwin, a type of selection arising through the preference by one sex for certain characteristics in individuals of the other sex; a special case of intraspecific competition or the evolutionary result of the struggle between the individuals of one sex for reproductive access to individuals of the other sex; in males it is expressed in competition for social dominance or for particular resources, or by physical combat; or in females by behaviors that control mate choice; sexual selection produces phenotypic traits with potential costs to survival that are outweighed by reproductive fitness gains
Secondary sexual characteristics: those characteristics that develop just before an organism’s adult phase that may distinguish the sexes of a species
Sexual Dimorphism: when males and females differ in phenotype due to the action of sexual selection on that phenotype
Mimicry: the resemblance of one organism to another or to an object in its surroundings for concealment and protection from predators
Mimicry System: The close external resemblance of an organism, the mimic, to some different organism (or inanimate object), the model, such that the mimic benefits from the mistaken identity, by seeming to be unpalatable or harmful or camouflaged and not detected
Batesian Mimicry: one or more harmless species of low population density evolve to mimic one or more potentially harmful and plentiful species exhibit aposematic (warning) colors/phenotypic traits
Müllerian Mimicry: mimicry in which all the species are unpleasant or toxic organisms, and thus all the species in the system are harmful “models” mimicking each other, and therefore the aposematic coloration/phenotype is learned by predators as a deterrent regardless of which species it encounters first
Mertensian Mimicry: deadly prey species mimics a less dangerous species’ aposematic phenotype so that the predator can survive to learn to avoid the aposematic phenotype, benefitting both the mildly harmful and the deadly species
Aggressive mimicry: When a predator uses any form of camouflage so that it cannot be detected by its prey species, and, therefore, the prey individuals come close to the predator, unaware that it is there, and then the predator can strike and take the prey
Phenotypic plasticity: variation in the phenotype expressed in response to environmental changes with no difference in underlying genotype and indicative of underlying genotypic plasticity
Neutral Theory: at the molecular level most evolutionary changes and most of the variation within and between a species is not caused by natural selection but by genetic drift of mutant alleles that are neutral in fitness

Chapter 16: Species and Similarity: On Being the Same Yet Different.