Anthropology Test One Study Guide: PHYSICAL ANTHROPOLOGY Anthropology: divided into four main subfields; cultural, or social anthropology, linguistic anthropology, archaeology, and physical or biological anthropology Concerns all aspects of humanity across space and time Offer powerful means of explaining variation in human adaptations Cultural: (social) study of the global patterns of belief and behavior in human cultures both past and present 19th century when travel brought Europeans in contact with other cultures Ethnographic studies: religion, ritual, myth, diet, subsistence strategies, technology, gender roles, child rearing practices Linguistic: study of human speech and language, including the origins of language as well as specific languages. Able to trace historical ties between languages past relationships between human populations Study the process of language acquisition in infants Archaeology: study of earlier cultures and lifeways by anthropologists who specialize in the scientific recovery, analysis, and interpretation of the material remains of past societies. Collect information from artifacts and structures left behind Excavated to gain information about human behavior Biological/ physical: study of human biology within the framework of evolution and with an emphasis on the interaction between biology and culture. Physical: (original term) initial interests in describing human physical variation. Biological: shift in emphasis to more biological topics- genetics, evolutionary biology, nutrition, physiological adaptations, growth and development Paleoanthropology: study of anatomical and behavioral human evolution as shown in the fossil record Study of earlier hominins- their chronology, physical structure, archaeological remains, habitats Anthropometry: measurement of human body parts Measuring, describing, explaining the obvious differences among various human populations with particular attention to skin color, body proportions, and shape of head and face Osteology: the study of skeletal material Human: focuses on the interpretation of skeletal remains from archaeological sites, skeletal anatomy, bone physiology, growth and development Forensic anthropology: directly related to osteology and paleoanthropolgy applied approach to dealing with legal matters Identifying and analyzing human remains Human Adaptation and Variation- traits that typify certain populations can be seen as having evolved as biological adaptations or adjustments to local environmental conditions. Molecular Anthropology: investigate evolutionary relationships between human populations as well as between human and non-human primates Examine similarities and differences in DNA among individuals, populations, and species Primatology: the study of the biology and behavior of non-human primates Scientific Method: an approach to research whereby a problem is identified, a hypothesis is stated, and that hypothesis is tested by collecting and analyzing data Hypothesis: a provisional explanation of a phenomenon require verification of falsification through testing Theory: powerful explanation that withstands the test of time Testable Falsifiability: could be disproven EVOLUTIONARY THEORY Great Chain of Being: life is arranged from simplest to most complex species Fixity of species: (stasis) the world is fixed and unchanging John Ray: (1627-1705) brought order to science Biological species concept: clearly defined: recognized that groups of plants and animals could be differentiated from other groups by their ability to mate with one another and produce offspring Reproductive isolation: because of genetic differences some organisms are prevented from mating with members of other groups Introduced genus and species Species: can mate and produce fertile offspring Genus: share similar characteristics Carolus Linnaeus: (1707-1778) father of modern taxonomy or the science of classification. Developed a method of classifying plants and animals Binomial nomenclature: The scientific naming of species whereby each species receives a Latin or Latinized name of two parts, the first indicating the genus and the second being the specific epithet. genus and species names are used to refer to species (homo sapiens) Differing degrees of relatedness between living things Added two more categories: class and order Became a four level system Systema Naturae (1735): 12 editions, the 10th is considered the starting point of modern zoological nomenclature. Buffon: (1707-1788) recognized the dynamic relationship between the external environment and living forms Natural History (1749) importance of change in the universe and in the changing nature of species Adaptation: When groups of organisms migrate to new areas, they gradually become altered as a result of adapting to new environment First to say the earth was older that 6,000 years old: 76,000 Jean Lemarack: (1744-1829) first to explain evolutionary process Suggested dynamic relationship between species and the environment such that if the external environment changed an animals activity patterns would also change Would result in increase or decrease of certain body parts, those body parts would be modified Offspring would acquire these characteristics Inheritance of acquired characteristics George Cuvier: (1769-1832) introduced the concept of extinction to explain the disappearance of animals represented by fossils Father of paleontology: studied fossils Proposed catastrophism to explain fossil record Earths geological landscape is the result of violent cataclysmic events Thomas Malthus: (1766-1834) english economist who wrote, ?Essay of Population?. Argued for limits to human population growth because in nature the tendency for populations to increase is constantly being held in check by the availability of resources Population size increase exponentially while food/resources remain relatively stable Influenced Charles Darwin and Alfred Russel Wallace in their separate discoveries of natural selection. He argued for limits to human population growth because, as he pointed out, in nature the tendency for populations to increase is constantly being held in check by the availability of resources. Charles Lyell: (1797-1857) founder of modern geology First to believe earth was millions of years old Principles of Geology (1830) argued that the geological processes we see today are the same as those that occurred in the past Called geological uniformitarianism Alfred Wallace: (1823-1913) discovered the key to the evolutionary process In 1855, he published an article suggesting that current species were descended from other species and that the appearance of new ones was influenced by environmental factors. Sent another paper to Darwin in 1858 describing evolution as a process driven by competition and natural selection. Charles Darwin: (1809-1882) naturalist H.M.S. Beagle voyage 1831-1836 On the Origin of Species: published on 24 November 1859, is a work of scientific literature which is considered to be the foundation of evolutionary biology Traveled to Galapagos Islands and studied finches. 3 and a half years on land and 18 months at sea. Natural selection: individuals with favorable variations would survive and reproduce but those with unfavorable variations would not, only the strong will survive. Fitness: individuals genetic contribution to the next generation compared to that of other individuals Natural selection: All species capable of producing offspring at faster rate than food supply increases Biological variation within all species There is competition among individuals Individuals who posses favorable variations have an advantage Environmental context determines if a trait is beneficial Traits are inherited and passed down to next generation Over long periods of time successful variations accumulate in a population CELLS, DNA, GENES Genome: The entire genetic makeup of an individual or species Cell: fundamental units of life in all living organisms Prokaryotic: one celled organisms such as bacteria Eukaryotic: structurally more complex- three dimensional structure composed of carbohydrates, lipids, nucleic acids, and proteins, nucleus ORGANELLES: a specialized subunit within a cell that has a specific function, and is usually separately enclosed within its own lipid bilayer. Cytoplasm: portion of cell contained within cell membrane, excluding nucleus. Consists of simifluid material and contains numerous structures Mitochondria: sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. In addition to supplying cellular energy, mitochondria are involved in a range of other processes, such as signaling, cellular differentiation, cell death, as well as the control of the cell cycle and cell growth. mtDNA: the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the energy from food into a form that cells can use. Ribosomes: structures composed of a form of RNA called ribosomal RNA and protein found in cells cytoplasm and essential to manufacture of proteins Nucleus: structure found in all eukaryotic cells contains chromosomes (nuclear DNA) Two types of cells: somatic cells and gametes Somatic cells: cellular components of body tissues such as muscle, bone, skin, nerve, heart, and brain diploid cell (contains two sets of chromosomes, one from each parent) Gametes: sex cells, specifically involved in reproduction and are not important as structural components of the body haploid cells (contain a complete set of chromosomes) Egg cells, produced in female ovaries Sperm cells, develop in male testes DNA (deoxyribonucleic acid) the double stranded molecule that contains the genetic code, main component of chromosomes Very basis of life, directs all cellular functions Composed of two chains of even smaller molecules called nucleotides: composed of a sugar, phosphate, and one of four DNA bases stacked on top of each other to form a chair that is bonded to another nucleotide chain, together these two chains twist to form a double helix Twisted ladder: sugars and phosphates form two sides, bases and bonds form rungs Organic Bases adenine, guanine, thymine, cytosine (A, G, T, C), base pairs can only from between A-T and G-C DNA Replication: for organisms to grow and injured tissues to heal, somatic (body) cells have to multiply they do this by dividing to make exact copies of themselves Cell divides one time to produce two ?daughter cells? which both have full set of genetic material: before cell can divide its DNA must replicate Begins when enzymes (specialized proteins that initiate and direct chemical reactions in the body) break the bonds between bases throughout the DNA molecule two previously joined strands have their bases exposed Exposed bases attract unattached DNA nucleotides that are free floating in cell nucleus Attraction between bases occurs in complementary way: two parental nucleotide chains serve as templates for forming new strands as each new strand forms its bases are joined to bases of an original strand When process is complete there are two double stranded DNA molecules exactly like the original one Protein Synthesis: Proteins complex, three dimensional molecules that function through their ability to bind to other molecules DNA directs protein synthesis: ex hemoglobin, enzymes, collagen, hormones, regulatory proteins Each protein is composed of a chain of amino acids, which link together by peptide bonds to form proteins or that function as chemical messengers and as intermediates in metabolism.. There are 20 AAs, 8 of which must be obtained from food, the remaining 12 are produced by cells these 20 AA are combined in different amounts and sequences to produce different proteins Proteins differ in the number and sequence of AA?s Protein synthesis takes place outside cell nucleus in the cytoplasm at the ribosome Transcription: DNA can?t leave cells nucleus 1st copy the DNA message into a from of RNA called messenger RNA (mRNA) which can pass through nuclear membrane into cytoplasm DNA splits and free floating bases attach to active strand mRNA is formed from one half of DNA strand. After attachment and copy, mRNA detaches and DNA re-closes Translation: mRNA obtains DNA code and travels to ribosome in cytoplasm mRNA moves along ribosome. Every set of 3 mRNA bases that specify one amino acid is called a codon. transfer RNA (tRNA) then picks up amino acid and travels to ribosome which then matches to codons in the mRNA and joins together amino acids then form a polypeptide chain which will become the protein RNA (ribonucleic acid): a biologically important type of molecule that consists of a long chain of nucleotide units. Each nucleotide consists of a nitrogenous base, a ribose sugar, and a phosphate. RNA is very similar to DNA, but differs in a few important structural details: in the cell, RNA is usually single-stranded, while DNA is usually double-stranded; RNA nucleotides contain ribose while DNA contains deoxyribose (a type of ribose that lacks one oxygen atom); and RNA has the base uracil rather than thymine that is present in DNA. mRNA: a molecule of RNA encoding a chemical "blueprint" for a protein product. mRNA is transcribed from a DNA template, and carries coding information to the sites of protein synthesis: the ribosomes. tRNA: a small RNA molecule that transfers a specific active amino acid to a growing polypeptide chain at the ribosomal site of protein synthesis during translation. GENE: a segment of DNA that specifies the sequence of amino acids in a particular protein Exons: parts that code transcribed in to mRNA Introns: non-coding DNA removed in mRNA synthesis Codon: A sequence of three adjacent nucleotides constituting the genetic code that specifies the insertion of an amino acid in a specific structural position in a polypeptide chain during the synthesis of proteins. CHROMOSOMES AND CELL DIVISION: Mutation: change in the gene occurs when the sequence of bases in a gene is altered, interfere with organisms ability to produce vital proteins Point mutation: change in a single base in a DNA sequence, can be beneficial but can cause disease like sickle cell anemia In evolution it is the most important source of new variations in populations Chromosome: discrete structures composed of DNA and protein found only in the nucleus of cells during normal cell function, single stranded but during cell division join to become double stranded Each species characterized by specific number of chromosomes: humans have 46, 23 from each parent Centromere: constricted portion of a chromosome, after replication the two strands of a double stranded chromosome join here Autosomes: carry genetic information for physical characteristics (except sex determination) Sex chromosomes: X and Y chromosomes females have 2 X?s, males have one X one Y Somatic cell: carry the pairs of chromosomes from each parent, contain 23 pair: 22 autosomes and 1 sex chromosome Locus: specific location on a chromosome where a gene or DNA is Allele: alternate forms of gene Karyotype: the number and appearance of chromosomes in the nucleus of a eukaryote cell. Cell division: Mitosis: cell division of somatic cell ?simple cell division? cells only divide once Two daughter cells formed, each identical copy of parent Meiosis: cell division of gametes (ovaries and testes) two divisions resulting in 4 daughter cells with 23 chromosomes each (haploid cells) only have 23 chromosomes because it will join with another gamete to form 46 chromosomes during human reproduction Recombination: only happens during meiosis the process by which genetic material is broken and joined to other genetic material, Involves crossing over: process of exchange of DNA between homologous chromosomes Evolutionary significance: increases genetic variation at a faster rate then mutation alone offspring in sexually reproducing species represent the combination of genetic information from two parents Chromosomal Mutations: changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. Mutations are caused by radiation, viruses, transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication Down Syndrome: chromosomal disorder caused by the presence of all or part of a 3rd instead of pair of the 21st chromosome, which is one of the 23 pairs of chromosomes found in humans. Called trisomy 21 Problems with Meiosis: if process does not go exactly right normal fetal development cannot occur if chromosomes do not completely separate (nondisjunction) serious problems can develop Nondisjunction: one daughter cell receives two copies of affected chromosome while other daughter cell receives none resulting in a zygote with either 45 or 47 chromosomes Trisomy: presence of 3 copies of a particular chromosome trisomy 21: downsyndrome: caused by the presence of three copies of chromosome 21 Turner?s syndrome: (XO) a chromosomal abnormality in which all or part of one of the sex chromosomes is absent, affected females are short-statured, have broad chests and webbed necks and are sterile Klinefelter?s syndrome: (XXY) a condition in which human males have an extra X sex chromosome, affected males have reduced testicular development, reduced facial and body hair, some breast development and reduced fertility Mendelian Genetics Gregor Mendel (1822-1884) addressed the question of heredity Principle of Segregation: genes occur in pairs because chromosomes occur in pairs. During gamete fertilization, the members of each pair of alleles separate, so that each gamete contains one member of each pair. During fertilization, the full number of chromosomes is restored, and members of gene or allele pairs are reunited. Principle of Independent Assortment: the distribution of one pair of alleles into gametes does not influence the distribution of another pair. The genes controlling different traits are inherited independently of one another. Phenotype: the observable or detectable physical characteristics of an organism; the detectable expression of genotypes, frequently influenced by environmental factors. Genotype: the genetic makeup of an individual, it can refer to an organism?s entire genetic makeup or to the alleles at a particular locus. Homozygote: Having two of the same alleles at a given locus. Example YY or yy Heterozygote: Having two different alleles at a given locus. Example Yy Dominant: Mask the effect of recessive genes. Must be YY or Yy Recessive: Must have two recessive alleles before that trait is expressed. Must be homozygous yy Codominant: The expression of two alleles in heterozygotes. Both alleles affect the phenotype, so neither is dominant. Punnett Square: a diagram that is used to predict an outcome of a particular cross or breeding experiment. Shows the possible genotypes. Dihybrid: Two traits with two alleles crossed ABO Blood Types: Mendelian traits in humans. It is governed by three alleles, A, B, and O. These alleles determine which ABO blood type an individual has by coding for the production of molecules called antigens on the surface of red blood cells. Possibilities: A, B, AB, and O. The O is recessive to both A and B, so if a person is O, he or she is homozygous (two copies) of O. Both A and B are dominant to O, so an individual with blood type A can actually have one of two genotypes, AA or AO. The same is true for B. When both A and B are present, they are codominant. Antigen: Large molecules found on the surface of cells. Several different loci govern various antigens on red and white blood cells. (Foreign antigens provide an immune response) Antibody: Proteins that are produced by some types of immune cells and that serve as major components of the immune system. Antibodies recognize and attach to foreign antigens on bacteria, viruses, and other pathogens. Universal Donor: O Universal Recipient: AB Evolutionary Mechanics and Population Genetics: Pedigree Chart: A diagram showing family relationships. It?s used to trace the hereditary pattern of particular genetic traits. Box=male Circle=woman Filled in=Affected Modes of Inheritance: Autosomal Dominant: Dominant allele on autosomes, doesn?t skip a generation, and affects all sexes the same. Example: Brachydactyl Autosomal Recessive: An autosome can skip a generation and an affected offspring can be produced by two phenotypically normal parents. But when both parents have the trait all the offspring will be affected. Sexes are equally affected. *Sex-linked traits are controlled by genes located on the X and Y chromosomes* X-Linked Recessive: Women can be recessive and heterozygous, and are therefore carriers. While men will almost all be affected because they only have one X chromosome, so even if it is recessive it will be expressed X-Linked Dominant: (Males): Only one copy of the gene is necessary for the effect to be expressed. All daughters of an affected father will also be affected but none of his sons will be affected (unless the mother is also affected). In addition, the mother of an affected son is also affected (but not necessarily the other way round). Y-Linked: Only y chromosome is affected so it is only in males. Every y-linked trait expressed. Mitochondrial: condition is expressed in people with mutations in mitochondrial DNA (mtDNA). Affected equally Albinism: A metabolic disorder caused by an autosomal recessive allele that prevents the production of a pigment called melanin. Characterized by unusually light hair, skin, and eyes. Discrete vs. Complex Traits: Discrete traits are controlled by one genetic locus; No continuous variation. Example=ABO Blood groups. Complex traits are polygenic, controlled by two or more genetic loci, with continuous variation. They can also be influenced by environment. Example=Height. Polygenic: Traits influenced by genes at two or more loci. Each gene contributes to the trait. Many are influenced by environmental factors as well, such as nutrition. Example: Skin color, eye color, and hair color Pleiotropy: A single gene that influences several seemingly unrelated phenotypic traits. Natural Selection: Evolution is a two stage process. 1. The production and distribution of variation (Inherited differences among individuals; the basis of all evolutionary change Genetic and Environmental variation) 2. Natural selection acting on this variation. *Evolution occurs when there is a change in allele frequencies in a population from one generation to the next. Individuals do not evolve, populations do. Adaptation: An anatomical, physiological, or behavioral response of organisms or populations to the environment. Adaptations result from evolutionary change (Specifically a result of natural selection) Fitness: a measure of the relative reproductive success of individuals. It can be measured by an individuals genetic contribution to the next generation compared to that of other individuals. Variation: Inherited differences among individuals; the basis of all evolutionary change. Microevolution: Small changes occurring within species, such as a change in allele frequencies. Macroevolution: Changes produced only after many generations, such as the appearance of a new species. Mechanisms of Evolution: Natural Selection: Survival and reproduction of some organisms is favored over others as a result of the traits they posses. Some alleles provide better fitness than others. Probability of survival and reproduction, not necessarily the strongest. Unit of selection=individual. Unit of evolution=population. Sickle Cell Anemia & Malaria: How natural selection explains negative traits surviving. Some negative traits might offer *advantages for heterozygotes (higher relative fitness). Sickle Cell Anemia is when the body makes sickle-shape red blood cells that don?t move easily through blood vessels which can result in clotting. Red blood cells break down when the parasite of malaria is attempting to attach. Creates a resistance to Malaria, therefore resulting in a benefit of sickle cell anemia. Heterozygote Advantage: describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. Mutation: Random genetic change in the genetic code. Mutations need to occur in the gametes (sex cells) or the mutation will not be passed to future generations. This is the ultimate source of all new variation (polymorphisms). Environmental factors can influence mutations. Mutation rates are slow. When mutation is combined with natural selection, evolutionary change not only can occur, but can occur more rapidly. Natural selection and population size determines whether a mutation will increase in frequency in a population. Types of mutations: Substitution-Point mutation (change in a single base) Frame Shift-Insertion or deletion Rearrangement-One or few bases gets set in the wrong place Genetic Drift: Evolutionary changes (that is changes in allele frequencies) produced by random factors. Tends to decrease genetic variation. Dependent on population size, frequencies will change more readily in smaller populations. Founders Effect: Formation of a new, small population from an older population Gene Flow: Movement of genes from one population to the next. Not precisely the same thing as migration. This will increase genetic variation within a population and decrease variation between two different populations. Migration: Refers to the movement of people, but gene flow refers to the exchange of genes between groups which can only occur if the migrants interbreed. Recombination: The exchange of genetic material between homologous chromosomes during meiosis. Population Genetic:s R.D. Lewontin: A leader in developing the mathematical basis of population genetics and evolutionary theory. Applied techniques from molecular biology to questions such as genetic variation and evolution. Population Genetics: The study of the frequency of alleles, genotypes, and phenotypes in populations from a microevolutionary perspective. Taking advantages of new discoveries that focus on DNA polymorphisms. These molecular applications are now being widely used to evaluate human variation at a microevolutionary level. Use this data to understand roles of natural selection, genetic drift, gene flow, and mutation. Gene Pool: The total complement of genes shared by the reproductive members of a population Breeding Isolates: Populations which are clearly isolated geographically and/or socially from other breeding groups. Geography plays a dominant role in producing these isolates by severely limiting the range of mates. Endogamy: Mating with individual?s from the same group. Not totally closed systems. Gene flow often occurs between groups, and individuals may chose mates from distant locations. Exogamy: Mating pattern whereby individuals obtain mates from groups other than their own. This has increased. Evolution: After identifying specific human populations, the next step is to find out what evolutionary forces, if any are operating on them. To determine whether evolution is taking place at a given genetic locus, we measure allele frequencies for specific traits. Then compare these frequencies with those predicted using the Hardy-Weinberg Equilibrium. Hardy-Weinberg Equilibrium: Establishes a set of conditions in a hypothetical populaton where no evolution occurs. These conditions are: An infinitely large population. No mutation. No gene flow. Natural selection isn?t operating. Mating is random. Thus creating a permanent equilibrium. This equilibrium model provides population geneticists a standard against which they can compare actual circumstances. Observed vs. Expected: If observed frequencies differ from those of the expected model, we can then say that evolution is taking place at the locus in question. If the observed and expected frequencies don?t differ enough then we can confidently say that evolution is not occurring at a particular locus in a population. This is often what happens, resulting in an inability to clearly define evolutionary change at the particular locus under study. p+q=1: Used in microevolutinary study using a genetic trait that follows a simple Mendelian pattern and has only two alleles with three possible genotypes. P represents frequency of dominant allele and Q represents the frequency of recessive allele. The sum of their separate frequencies must be 1 (100% of alleles at the locus in question). p2+2pq+q2=1: To determine the expected proportions of genotypes, we compute the chances of the alleles combining with one another into all possible combinations. The chances of all possible combinations occurring randomly can be shown as the above equation. P2 is the frequency of the codominant genotype, 2pq is the frequency of the heterozygous dominant genotype, and q2 is the frequency of the homozygous recessive genotype, where p is the frequency of the dominant allele and q is the frequency of the recessive allele in a population. Patterns of Evolution: Macroevolution: Specification (process by which a new species evolves from an earlier species) is the most fundamental of macroevolution. Involves some form of isolation. Long term process of a new species being formed. Biological Species Concept: A depiction of species as groups of individuals capable of fertile interbreeding but reproductively isolated from other such groups. The way new species are first produced involves some form of isolation. Recognition Species Concept: A depiction of species in which the key aspect is the ability of individuals to identify members of their own species for purposes of mating (and to avoid mating with other species)> In theory, this type of selective mating is a component of a species concept emphasizing mating and is therefore compatible with the biological species concept. Ecological Species Concept: The concept that a species is a group of organisms exploiting a single niche. This view emphasizes the role of natural selection in separating species from one another. Niche: The position of a species within its physical and biological environments. A species ecological niche is defined by such components as diet, terrain, vegetation, type of predators, relationships with other species, and activity patterns, and each niche is unique to a given species. They make up the ecosystem. Speciation: Process by which a new species evolves from an earlier species. Using the phylogenetic species concept, populations are splitting into separate species based on identifiable parental pattern of ancestry. Anagenesis: A pattern of evolution that results in a linear descent with no branching or splitting of the population. The replacement of an ancestral species by a daughter species over time; the ancestral species becomes extinct Reproductive Isolation: Gene flow is prevented between two populations of the same species. Reproductive mechanisms are factors such as: mating and season calls. Chronospecies: A new organism may be derived from his ancestor by a slow, steady evolutionary change, resulting in a new species. Cladogenesis: The splitting of one species into two clades, usually because of geographical isolation, and also reproductive isolation. Allopatric: Living in different areas. This pattern is important in the divergence of closely related species from each other and from their shared ancestral species because it leads to reproductive isolation. Papapatric: Only partial reproductive isolation is required, so that the ranges of the populations may be partially overlapping. A hybrid zone would form in an area between the two partially separated populations. Sympatric: Theorized to occur completely within one population with no necessary reproductive isolation. Two species result from one population that occupies the same geographical locality. Not as well supported. Sexual Dimorphism: Differences in physical characteristics between males and females of the same species. Example. Women being smaller then men on average in the same population. Interspecific: Between species. Variation represents differences between reproductively isolated groups. Intraspecific: Within species. Refers to variation seen within the same species Paleospecies: Species defined from fossil evidence, often covering a long time span. Derived: Referring to characters that are modified from the ancestral condition and thus diagnostic of particular evolutionary lineages. Ancestral: Referring to characters inherited by a group of organisms from a remote ancestor and thus not diagnostic of groups (lineages) that diverged after the character first appeared. Genus: A group of closely related species. More closely related than they are to species from another genus. Adaptive Radiation: The relatively rapid expansion and diversification of life-forms into new ecological niches. Results from a species rapidly diverging into as many variations as two factors will allow: 1. Adaptive potential or ability to change under new circumstances 2. Adaptive opportunities of the available niches. Tempo and Mode of Evolution: Macroevolution can?t be explained solely in terms of slowly accumulated microevolutionary changes. Macroevolution is only partly understandable through microevolutionary models. Phyletic Gradualism: Change accumulates gradually in evolving lineages. The complete fossil record of an evolving group would display a series of forms with finely graded transitional difference between each ancestor and its descendants; that is many ?missing links? would be present. However, transitional forms are only rarely found and this view is questioned. Punctuated Equilibrium: The concept that evolutionary change proceeds through long periods of stasis punctuated by rapid periods of change. Test Question Elephants in Uganda are heavily poached for their tusks and now the elephants born without tusks have gone from 1% to 15% to 38 % in the last 70 years, because of this selective pressure, eventually there will be none with tusks.
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