Evolution

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Microevolution

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describes the details of how populations of organisms change from generation to generation and how new species originate

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macroevolution

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describes patterns of changes in groups of related species oevr broad periods of geologic time. The patterns determine phylogeny

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phylogeny

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the evolutionary relationships among species and groups of species

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Lamark

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earliest advocate for evolutionary ideas whose theory included use and disuse, inheritance of acquired characteristics, and natural transformation of species

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Use and Disuse

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lamarck- described how body parts of organisms can develop with increased usage, while unused parts weaken. This idea was correct, as is commonly observed among atheletes who train for competitions

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inheritance of acquired chracteristics

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lamarck- described how body features acquired during the lifetime of an organism (such as muscle bulk) could be passed on to offspring. This, however, was incorrect, only changes in the genetic material of cells can be passed on to offspring.

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natural transformation of species

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lamarck- described how organisms produced offspring with changes, transforming each subsequent generation into a slightly different form toward some ultimate, higher order of complexity. Species did not become extinct nor did they split and change into two or more species, this idea was also incorrect

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natural selection

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Darwin's theory, also called survival of the fittest, was the driving force of evolution now called DARWINISM.

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Neo-Darwinism

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or the synthetic theory of evolution, or modern synthesis.. the incorporation of genetics into evolutionary thinking

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Evidence for Evolution

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proven through paleontology, biogeography, embryology, comparative anatomy, and molecular biology

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Paleontology

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provides fossils that reveal the prehistoric existence of extinct species. As a result, changes in species and the formation of new species can be studied

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Biogeography

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uses geography to descrive the distribution of species. This information has revealed that unrelated species in different regions of the world look alike when found in similar enviroments. This provides strong evidence for the role of natural selection in evolution

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Embryology

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reveals similar stages in development among related species. The similariteis help establish evolutionary relationships

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ontogeny

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similar stages in development

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Comparative anatomy

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describes two kinds of structures that contribute to the identification of evolutionary relationships among species

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Homologous Structures

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body parts that resemble one another in different species because they have evolved from a common ancestor. Because anatomy may be modified for survival, they may look different but will resemble one another in pattern.

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Analogous Structures

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body parts that resemble one another in different species, not because they have evolved from a common ancestor, but because they evolved independently as adaptations to their enviroments.

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Molecular Biology

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examines the nucleotide and amino acid sequences of DNA and proteins from different species. Closely related species share higher percentages of sequences than species distantly related. In addition, all living things share the same genetic code. This data strongly favors evolution of different species through modification of ancestral genetic information

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Natural Selection

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the differenes in survival and reproduction among individuals in a population as a result of their interation with the enviroment

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adaptations

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superior traits which increase an individuals's fitness

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fitness

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relative ability to survive and leave offspring

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Darwin's arguements about natural selection

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populations possess an enormous reproductive potential, population sizes remain stable, resources are limited, individuals compete for survival, there is variation among individuals in a population, much variation is heritable, only the most fit individuals survive, and evolution occurs as advantageous traits accumulate

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Stabilizing Selection

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elimates individuals that have extreme or unusual traits. Under this condition, individuals with the msot common trait are the best adapted, while individuals who differ from the common form are poorly adapted. As a result, this maintains the existing population frequencies of common traits while selecting against all other trait variations, like height variations in humans

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Directional Selection

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favors traits that are at one extreme of a range of traits. Traits at the opposite end are selected against, and if it continues for many generations, favored traits become more and more extreme, leading to distinct changes in the allele frequences of the population, as in industrial melanism

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Insecticide resistance

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occurs as a result of directional selection. Individuals with some degree of resistance to the insecticide will survive and produce offspring, and after several generations, the population will consist of nearly all insecticide-resistance individuals

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peppered moth

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provides an example of directional selection of moth color from a light to dark color. WIth the advent of the industrial revolution, soot killed the pollution sensive lichens, exposing the dark tree bark below, so then the dark form of the moth became better camoflauged and increased in frequency. The light form of the moth continued to dominate populations in unpolluted areas outside of London.

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Industial Melanism

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the selection of dark colored (melanic) varieties in various species of moths as a result of industrial pollution

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Disruptive selection

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or diversifying selection, occurs when the enviroment favors extreme or unusual traits while selecting against common traits, as in height variations in weeds of lawns and in the wild

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Sexual Selection

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differential mating of males (sometimes females) in a population. SInce females make a greater energy investment in offspring, they increase their fitness by maximizing the quantity of offspring produced. Thus traits that allow males to increase their mating frequency have a selective advantage and increse in frequency within the population, as in weight variation in adult elephant seals

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male competition

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leads to contests of strength that award mating opportunities to the strongest males. The evolution of antlers, horns, and large stature or musulature are examples of this kind of sexual selection

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Female Choice

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leads to traits or behaviors in males that are attractive to females. Colorful bird plumage or elaborate mating behaviors are examples

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Sexual Dimorphism

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differences in the appearance of males and females due to sexual selection, therefore it is a form of disruptive selection

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Artifical Selection

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a form of directional selection carried out by humans when they sow seeds or breed animals that possess desirable traits. Since it is carried out by humans, it is not "natural"

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Sources of Variation

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necessary in order for natural selection to operate, includes mutations, sexual reproduction, diploidy, outbreeding, and balanced polymorphism

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Mutations

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provide the raw material for new variation. All other contributions to variation occur by rearranging existing alleles into new combinations. This, however, can invent aleles that never before existed in the gene pool

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Sexual Reproduction

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creates indivuals with new combinations of alleles through genetic recombination and occurs during crossing over, independent assortment of homologues, and random joining of gametes

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crossing over

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exchanges of DNA between nonsister chromatids of homologous chromosomes during prophase I of meiosis

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independent assortment of homologues

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during metaphase I, creates daughter cells with random combinations of maternal and paternal chromosomes

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random joining of gametes

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during fertilization, contributes to the diversity of gene combinations in the zygote

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genetic recombiation

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rearrangments of alleles in sexual reproduction

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Dipoloidy

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the presence of two copies of each chromosome in a cell. In the heterozygous condition (when two differnt alleles for a single gene locus are present) the recessive allele is hidden from natural selection. As a result, more variation is maintained in the gene pool

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Outbreeding

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mating with unrelated partners, increases the possibility of mixing differnt allels and creating new allele combinations

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balanced polymorphism

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mainenance of different phenotypes in a population. Often, a single phenotype provides the best adaptation, while other phenotypes are less advantageous. In these cases, the alleles for the advantegous trait increase in frequency while the others decreases. However, there are several examples of polymorphism as shown in the heteozygous advantage, hybrid vigor, and frequency-dependent selection

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Heterozygous advantage

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occurs when the heterzygous condition bears a greater selective advantage than either homozygous condition. As a result, both alleles and all three phenotypes are maintained in the population by selection (balanced polymorphism)

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Hybrid Vigor

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or heterosis, describes the superior quality of offspring resulting from crosses between two different inbred strains of plants. The superior hybrid quality results from a reduction of loci with deleterious homozygous recessive conditions and an increase in loci with heterzygote advantage (balanced polymorphism) a better organism is the product of two bad organisms

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example of heterzygote advantage

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sickle cell anemia and malaria resistance

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Frequency-dependent selection

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or minority advantage, occurs when the least common phenotpes have a selective advantage. Common phenotypes are selected against until the rare phenotypes become increased in number and then they lose their selective advantage and so forth and so forth (balanced polymorphism)

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search image

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what predators form to standardize the most common form of its prey and therefore optimizes its search effort, leading to frequency-dependent selection

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neutral variation

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variation that does not have selective value, like the fingerprint patterns among humans.

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Natural Selection (frequences)

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the increase of decrease in allele frequencies due to the impact of the enviroment

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mutations

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introduce new alleles that may provide a selective advantage. In general, however, most mutations are DELETERIOUS, or harmful

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Gene flow

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the introduction or removal of alleles from the population when individuals leave (emigration) or enter (immigration) the population

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Genetic Drift

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a RANDOM increase of decrease of alleles, in other words, some alleles may increase or decrease for no other reason than by chance. When populations are small the effect of genetic drift can be very strong and can dramatically influence evolution. Includes the founder and bottleneck effect

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founder effect

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type of genetic drift when allele frequencies in a group of migrating individuals are, by chance, not the same as that of their opulation of origin.

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bottleneck

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type of genetic drift that occurs when the population undergoes a dramatic decrease in size. Regardless of the cause of this (natural catastophe, predation, or disease) the small population results become severely vulnerable to genetic drift.

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Nonrandom Mating

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occurs when individuals chose mates based on their particular traits. It also ocurs when mates chose only nearby individuals. The most commonly observed is inbreeding and sexual selection

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Inbreeding

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type of nonrandom mating when individuals mate with relatives

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Sexual Selection (frequencies)

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type of nonrandom mating when femails choose males based on their attractive appearance or behavior or their ability to defeat other males in contests

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genetic equilibrium

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when the allele frequences in a population remain constant from generation to generation also called the Hardy-Weinberg Equilibrium

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Conditions of a Hardy-Weinberg Equilibrium

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all traits are selectively neutral (no natural selection), mutations do not occur, the population must be isolated from other populations (no gene flow), the population is large (no genetic drift), and mating is random

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Hardy-Weinberg Equation

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Allele frequences for each allele (p,q), frequency of homozygotes (p2, q2), and frequency of heterozygotes (pq + qp = 2 pq) so then p+q =1 and p2 + 2pq + q2 = 1

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Hardy-Weinberg Equation

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Allele frequences for each allele (p,q), frequency of homozygotes (p2, q2), and frequency of heterozygotes (pq + qp = 2 pq) so then p+q =1 and p2 + 2pq + q2 = 1

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species

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a group of individuals capable of interbreeding

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speciation

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the formation of new species that occurs by allopatic or sympatric means. There can also be adaptive radiation

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Allopatric Speciation

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begins when a population is divided by a geographic barrier so that interbreeding between two resulting populations is prevented. One isolated, the gene frequences in the two populations can diverge due to natural selection, mutation, or genetic drift. If the gene pools sufficiently diverge, then the two new groups cannot breed

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Sympatric Speciation

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is the formation of a new species without the presence of a geographic barrier and can happen through balanced polymorphism, polyploidy, or hybridization

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balanced polymorphism (sympatric speciation)

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this among subpopulations may lead to speciation. Like when a population of insects possesses a poplymorphism for color. Each color provides a camoflauge to a differnt substrate, and if not camoflauged, the insect is eaten. Then only insects with the same clor can interact and then they become reproductively isolated from other subpopulations and their gene pools diverge

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Polyploidy

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the possession of two of more than the normal two sets of chromosomes. (3n, 4n, etc) It often ofcurs in plants and occurs as a result of nondisjunction of all chromosomes during meiosis. Since normal meiosis in the tetrapoloid individual will continure to produce diploid gametes, reproductive isolation with other indivituals in the population occurs immediately in a single generation

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hybridization

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occurs when two distinctly different forms of a species mate and produce progeny along a geographic boundary called a HYBRID zone. In some cases the genetic variation of the hybrids is greater than either of the parents and permits the population to evolve adaptations to the enviroment beyond the range of either parent. Exposed, they evetually diverge from both parent populations (sympatric)

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adaptive radiation

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the relatively rapid evolution of many species from a single ancestor. It occurs when the ancestral species colonizes an area where diverse geographic or ecological conditions are availble for colonization. Variants diverge as populations specialize for each set of conditions

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Isolating Mechanisms

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means of maintaining reproductive isolation and preventing gene flow, includes prezygotic isolating and postzygotic isolating mechanisms

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Prezygotic Isolating Mechanisms

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consists of mechanisms that prevent fertilization, includes habitat, temporal, behavioral, mechanical, and gametic isolation

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Habitat Isolation

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in prezygotic isolating mechanisms, occurs when species do not encounter one another

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Temporal Isolation

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in prezygotic isolating mechanisms, occurs when species mate or flower during different seasons or at different times of the day

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Behavioral Isolation

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in prezygotic isolating mechanisms, occurs when a species does not recognize another species as a mating partner because it does not perform the correct courtship rituals, display the proper visual signals, sing the correct mating songs, or release the proper chemicals (pheromones or scents)

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Mechanical Isolation

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in prezygotic isolating mechanisms, occurs when male and female genitalia are structurally incompatible or when flower structures select for different pollinators

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Gametic Isolation

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in prezygotic isolating mechanisms, occurs when male gametes do not survive in the enviroment of the female gamete (such as in internal fertilization) or when female gametes do not recognize male gametes

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postzygotic isolating mechanisms

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consists of mechanisms that prevent the formation of fertile progeny, which includes hybrid inviability, hybrid sterility, and hybrid breakdown

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Hybrid Inviabity

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in postzygotic isolating mechanisms, occurs when the zygote fails to develop properly and aborts or dies before reaching reproductive maturity

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Hybrid Sterility

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in postzygotic isolating mechanisms, occurs when hybrids become functional adults, but are reproductively sterile (eggs or sperm are nonexistent of dysfunctional). The mule is a sterile hybrid

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Hybrid Breakdown

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in postzygotic isolating mechanisms, occurs when hybrids produce offspring that have reduced viability or fertility

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Patterns of evolution

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includes divergent, convergent, parallel, and coevolution

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Divergent Evolution

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describes two or more species that originate from a common ancestor. This may happen as a result of allopatric or sympatric speciation or by adaptive radiation

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Convergent Evolution

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describes two unrelated species that share similar traits. The similarties arise not because they share a common ancestor but because each species has independently adapted to similar ecological conditions or lifestyles. The traits are called ANALOGOUS traits

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Parallel Evolution

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describes two related species or two related lineages that have made similar evolutionary changes after their divergence from a common ancestor

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Coevoltion

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is the tit-for-tat evolution of one species in response to new adaptations that appear in another species. Suppose a prey species will fair to catch prey, some varients in the predator population will be successful. Selection favors these successful variants and subsequent evolution results in new adaptations in the predator species

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Chemical Evolution

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the study of how life began

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Heteotroph Theory

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for the origin of life, proposes that the first cells were heterotrophs, organisms incapable of making their own food

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First Step of the Heterotroph Theory

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the earth and its atmosphere formed, the primorial atmosphere orginated from outgassing of the molten interior of the planet (through volcanoes) and consisted of CO, CO2, H2, N2, H2O, S, HCl (hydrocholoric acid), and HCN (hydrogen cynide), but little or no O2

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Second Step of the heterotroph theory

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The primordial seas formed, as the earth cooled, gases condenses to produce primordial seas consisting of water and minerals

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Third Step of the Heterotroph Theory

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Complex molecules are synthesizes; energy catalyzed the formation of organic molecules from inorganic molecules. An "organic" soup was formed. Energy was provided by UV, lightning, radioactivity, and heat. Complex molecules included acetic acid, formaldehyde, and amino acids which would later serve as monomers for the synthesis of polymers. Oparin and Haldane theorized that simple molecules werea ble to form only because O2 was absent, Stanly Miller performed an experiment

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A.I. Oparin and J.B.S. Haldane

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independently theorized that simple molecules were able to form only because O2 was absent. As a very reactive molecule, it would have prevented the formation of organic molecules by supplanting most reactants in chemical reactions

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Stanley Miller

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tested the theories of Oparin and Haldane by simulating an experiment under primordial conditions. he applied electric sparks to simple gases (but no O2) connected to a flask of heated water. After one week, the wate contained various organic molecules including amino acids.

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Fourth Step of the Heterotroph Theory

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Polymers and self-replicating molecules were synthesized, monomers combined to form polymers. Some of these reactions may have occured by dehydration condenstation, in which polymers formed form monomers by the removal of water molecules. THese are called proteinoids

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Proteinoids

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abioticaly produced polypeptides that can be experimentally produced by allowing amino acids to dehydrrate on hot, dry substances

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5th Step of the Heterotroph theory

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Organic molecules were concentrated and isolated into protobionts

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Protobionts

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precursors of cells, they were able to carry out chemical reactions enclosed within a border across which materials can be exchanged, but were unable to reproduce. Borders formed in the same manner as hydrophobic molecules aggregate to form membranes.

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Microspheres and Coacervates

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experimentally and abiotically produced protobionts that vhave some selectively permeable qualities

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6th step of the heterotroph theory

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Primitive heterotrpophic prokaryotes formed, the organic soup was a source or organic material of heterotrophic cells and as these cells reproduced, competition for organic material increased and led to natural selection

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heterotrophs

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living organisms that obtain energy by consuming organic substances, like pathogenic bacteria

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7th Step of the heterotrophic theory

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Primitive autotrophic prokaryotes were formed, as a result of mutation

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Autotroph

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cell that manufactures its own organic compounds using light energy or energy from inorganic substances. Cyanobacteria (photosynthetic bacteria), for example, are autotrophic prokaryotes that obtain energy and manufacture organic compounds by photosynthesis

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8th Step of the heterotrophic theory

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Oxygen and the ozone layer formed and abiotic chemical evolution ended, as a byproduced of photosynthetic actibity, oxygen was released and accumulated in the atmosphere, and the interaction of UV light and oxygen produced the ozone layer. Incoming UV light was absorbed which prevented it from reaching the surface of the earth, thus, the major source of energy for the abiotic syntehsis of organic molecules and primitive cells was terminated

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Last Step of the heterotrophic theory

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Eukarotes Formed (Endosymbiotic Theory)

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Endosymbiotic Theory

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states that eukaryotic cells orginiated from a mutually beneficial assiciation (symbiosis) among various kinds of prokaryotes. Specifically, mitochondria, chloroplasts, and otehr organelles established residence inside another prokaryote, producing a eukaryote

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Evidence for the endosymbiotic theory

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Mitochondira and Chlorplasts possess their own SNA, ribosomes of mitochondria and chloroplasts resemble those of bacteria and cyanobactera, they reproduce independently of their eukaryotic host cell, and teh theylakoid membranes of choloroplasts resemble the photosynthetic membrane of cyanobacteria, and all of these resemble parts of bacteria