Exam 1: Chapters 18, 19, 20, 23 Flashcards
Define evolution.
Accumulation of genetic changes within a population over time. Change in allele frequencies between generations.
Define population.
Group of individuals of one species that live in the same geographic area at the same time.
Does evolution matter to the person on the street?
Agriculture must deal with the evolution of pesticide resistance in pests. Medicine must respond to the rapid evolution of disease-causing organisms such as bacteria and viruses Conservation management of rare and endangered species uses evolutionary principles of population genetics. Rapid evolution of microorganisms in polluted soils is used in the field of bioremediation, in which microorganisms are employed to clean up hazardous-waste sites.
Did Darwin come up with the idea or mechanism of evolution?
No, evolution was developed long before he born. Aristotle saw much evidence of natural affinities among organisms. Leonardo da Vinci proposed fossils represented organism that have lived earlier.
Discuss the historical development of the theory of evolution with Jean Baptiste de Lamarck (18th Century).
Proposed that organisms change over time by natural phenomena, had vital force that changed them toward greater complexity over time, and could pass traits acquired during lifetime to offspring (concept of inheritance proposed).
Name the two people developed the framework for the modern concept of evolution and how it works at about the same time.
Alfred Russell Wallace & Charles Darwin
What influenced Darwin – leading to his theory of how evolution happens?
Observations during voyage of HMS Beagle.
Describe the voyage of the HMS Beagle.
5 year voyage. Darwin was an unpaid volunteer member of the voyage. Darwin studied fossils, animals, and plant geologic formations. Darwin observed lots of variation in nature between locations, including variation with similar climates. Galapagos finches and tortoise shells.
Define artificial selection.
Breeders and farmers could develop many varieties of domestic animals in just a few generations. This is the process of choosing certain traits and breeding only individuals that exhibited the desired traits.
Explain the Galapagos finches in Darwin’s voyage of the HMS Beagle.
Explain tortoise shells varied about islands in Darwin’s voyage of the HMS Beagle.
The shape of the shell would tell which island it came from.
Explain the Brassica oleracea in Darwin’s voyage of the HMS Beagle.
Artifical selection.
Explain the snail shells in Darwin’s voyage of the HMS Beagle.
Variation he observed in natural (wild) populations.
Explain Thomas Malthus’, an economist, ideas on human populations to natural populations that influenced Darwin.
Populations can grow geometrically unless limited by something. (1…2….4….8….16) Food supplies grow arithmetically and limit population growth. (1…. 2….. 3….. 4……) Influenced by geologist, Charles Lyell, idea that Earth was extremely old and geological processes occur slowly over time (until then, thought to be young).
Define adaptation.
An evolutionary modification that improves the chances of survival and reproductive success in a given environment.
Explain Darwin’s and Wallace’s idea that natural selection is the process of evolution.
Results in adaptations, which are evolutionary modifications and improve chances of survival and reproductive success (fitness) in a particular environment. Over time (many generations) accumulate changes in geographically separated populations produce new species. Genetic Drift.
Define natural selection.
Better adapted organisms are more likely to survive and become the parents of the next generation. As a result, the population changes over time; the frequency of favorable traits increases in successive generations, whereas less favorable traits become scarce or disappear.
What are the four premises of evolution by natural selection as proposed by Darwin and Wallace?
- Genetic variation: exists among individuals in a population.
- Overproduction: Reproductive ability of each species causes populations to geometrically increase over time.
- Organisms compete with one another: limits of population growth, or a struggle for existence. (for resources: food, living space, water, light)
- Differential reproductive success: Offspring with most favorable characteristics are most likely to survive and reproduce and pass genetic characteristics to next generation.
Why does natural selection occur?
Natural selection occurs because individuals with traits that make them better adapted to local conditions produce more offspring than those that lack such traits.
Explain modern synthesis or synthetic theory of evolution.
Combines Darwin’s theory of evolution by natural selection with modern genetics. Explains why individuals in a population vary, how species adapt to their environment, and DNA function.
What is the difference between the modern synthesis and Darwin’s original theory of evolution?
Modern synthesis combines the natural selection from Darwin’s and adds modern genetics. Note: Darwin did not know how inheritance functioned.
Modern synthesis explains Darwin’s observation of variation among offspring in terms of mutation. Define mutations.
Changes in DNA, such as nucleotide substitutions.
Define fossils and sedimentary rock.
Remains or traces of previously existing ancient organisms typically left in sedimentary rock. Sedimentary rock are layers that occur in sequence of deposition and recent layers on top of older ones.
What evidence from the fossil record supports the theory of evolution?
The fossil record illustrates transitions from unicellular organisms to multicellular organisms demonstrating that life has evolved through time. Few organisms that die become fossils and each fossil discovered is a separate test of the theory. Fossils provide a record of ancient organisms and some understanding of where and when they lived. Using fossils of organisms from different geologic ages, scientists can sometimes infer the lines of descent (evolutionary relationships) that gave rise to modern-day organisms.
Define index fossils.
Characterize a specific layer over large geographic areas. Fossils of organisms that existed for a relatively short geographic time but were preserved as fossils in large numbers.
Define radioactive isotopes or radioisotopes, radioactive decay, and half-life.
Present in a rock provide a means to accurately measure its age. As the radiation is emitted, the nucleus of the radioisotope changes into the nucleus of a different element; this process is known as radioactive decay. The time required for one half of the atoms of a radioisotopes to change into a different atom is known as half-life. Radioisotopes differ significantly in their half-lives.
Explain the whale evolution.
Define biogeography.
The study of the past and present geographic distribution of organisms. Geographic distribution of organisms has direct influence on evolution. Areas separated from others and contain organisms evolved in isolation that are unique in those areas.
Define continental drift.
At one time, continents were joined to form a supercontinent. Continental drift caused landmasses to separate and played major role in evolution.
Explain how fossil distribution occurred.
In continental drift, fossils are now found on separate continents.
What evidence for evolution is derived from comparative anatomy?
Homologous features indicate organism’s evolutionary affinities.
Define homologous features.
Basic structural similarities that may be used in different ways and are derived from same structure in a common ancestor.
Explain homology in animals.
Explain homology in plants.
Define analogous features called homoplastic or homoplasy
Evolved independently but similar functions in distantly related organisms. Demonstrates convergent evolution.
Define convergent evolution.
Organisms with separate ancestries adapt similar to comparable environments.
Explains convergent evolution in mammals.
Explain homoplasy in plants.
Define vestigial structures.
Nonfunctional or degenerate remnants of structures functional in ancestral organisms. Structures occasionally become vestigial as species adapt to different modes of life
Explain vestigial structures in the python.
How does developmental biology and molecular biology provide insights into the evolutionary process?
Genetic changes often result in gene mutations that affect development in different animals. Developmental biology unravels evolutionary patterns. Accumulation of genetic changes since organisms diverged and modified development patterns in more complex vertebrate embryos. Molecular evidence shows universal genetic code and conserved sequences of amino acids in proteins and of nucleotides in DNA.
Explain evolution now.
Darwin assumed evolution to be so gradual that humans cannot observe it. In fact, rapid evolution on a scale of years has been observed in many diverse organisms. Studies demonstrate that evolution is occurring now, driven by selective environmental forces (such as predation) that can be experimentally manipulated.
Explain the Reznick & Cook experiment.
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Define population genetics.
Study of genetic variability within a population and of the evolutionary forces that act on it.
What is a population’s gene pool.
Includes all the alleles for all the loci present in the population. More interested in alleles (variations of those genes)
What is the relationship between genotype, phenotype, and allele frequencies?
Frequency or percentage Genotype-diploid sand eukaryotes Allele frequency and consider the two alleles separately
Define allele frequency.
The proportion of a specific allele (that is, of A or a) in a particular population.
Define genotype frequency.
The proportion of a genotype in the population.
Define phenotype frequency.
The proportion of a phenotype in the population.
What is the Hardy-Weinberg Principle?
A model that predicts when allele and genotype frequencies do not change from generation to generation in a population that population is at genetic equilibrium. Allele frequency is most.
What is the significance of the Hardy–Weinberg principle as it relates to evolution?
The Hardy–Weinberg principle predicts allele and genotype frequencies for a population that is not evolving.
List five conditions required for genetic equilibrium in the Hardy-Weinberg Principle.
Hardy-Weinberg Principles applies only if… Mating is random in population No net mutations change allele frequencies Population is large Individuals don’t migrate between populations Natural selection does not occur
Explain inbreeding depression in mice.
Explain founder effect in genetic drift.
Genetic drift that occurs when a small population colonizes a new area. (e.g., chance long distance dispersal; introduction of non-native species)
What are the modes of natural selection?
Explain the heterozygote advantage in sickle cell anemia.
Explain the frequency-dependent selection in chichlid.
What the prezygotic barriers?
Temporal isolation Habitat isolation Behavioral isolation Mechanical isolation Gametic isolation
Explain prezygotic barrier temporal isolation in the frog.
Explain the postzygotic barrier hybrid inviability.
Interspecific embryos die during development.
Explain hybrid sterility in mules.
Explain allopatric speciation in pupfish.
Explain allopatric speciation in the squirrels.
Explain allopolyploidy in plants in sympatric speciation.
Called allopolyploidy because the two sets of chromosomes come from DIFFERENT species.
Explain sympatric speciation in animals.
Cichlids (“sik-lids”). Lakes in east Africa Diverse feeding habits in different species (algae, dead organic matter, fish scales, insect larvae, ect.) Evidence indicates different species evolved in the lakes they now inhabit (sympatrically) Great diversity in Cichlid species Rapidly going extinct due to human impacts
punctuated equilibrium vs gradualism.
Explain paedomorphosis in the salamander.
Explain adaptive radiation and adaptive zones in macroevolution.
Diversification of ancestral species into many new species in a relatively short period of time. Adaptive zones: new ecological opportunities not exploited by ancestral organism When many adaptive zones are empty, colonizing species diversify and exploit them .
Explain adaptive radiation in Hawaiian silverswords and honeycreepers
What are the six kingdoms and three domains of organisms?
Six Kingdoms:
- Archaea: prokaryotes
- Bacteria: prokaryotes
- Protista: unicellular, aquatic eukaryotes
- Fungi: molds, yeasts, and mushrooms
- Plantae: multicellular eukaryotes
- Animalia: multicellular eukaryotes
Three domains:
- Archaea: prokaryotes; peptidoglycan absent in cell walls
- Bacteria: prokaryotes; peptidoglycan present in cell walls
- Eukarya: all eukaryotes- protists, fungi, plants, animals
Given its distinguishing characters, how is an organism classified into the appropriate domain and kingdom?
If not prokaryote then assign to domain Eukarya
Check characteristics (Table 23-2) to determine appropriate kingdom
What is the difference between monophyletic, paraphyletic, and polyphyletic taxa?
Monophyletic group, or clade, includes all the descendants of the most recent common ancestor.
Paraphyletic group consists of a common ancestor and some, but not all, of its decendants.
Polphyletic group consists of organims that evolved from different recent ancestors.
How would reptiles and birds be classified differently by an evolutionary systematist vs cladist?
Cladists: insist that higher taxa be monophyletic and use shared derived characters to determine relationships.
Evolutionary Systematics: based on shared ancestral characters as well as shared derived character.
Phylogenetic trees are diagrams of hypothesized evolutionary relationships; cladograms are phylogenetic trees constructed by analyzing shared derived characters
Phylogenies & cladograms are hypotheses that are subject to testing and falsification.
Explain cladistics. How is a cladogram constructed?
Cladograms: phylogenetic trees
Cladogram indicates which taxa share a common ancestor
Select taxa of interest.
Select relevant characters: homologous characters,
Select outgroup (taxon for comparison).
Assume parsimony until contrary evidence is available.
- Interpret the characters and character states
- Identify which character states are primitive (plesiomorphic).
- Group taxa with shared derived character states (synapomorphies).
