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biology exam 1
| Question | Answer |
|---|---|
| what is evolution? | change in allele frequency within a population across generations |
| how does natural selection lead to evolutionary change in a population? | individuals more successfully adapted to the env. have greater fitness |
| how does genetic drift lead to evolutionary change in a population ? | causes evolution through random changes in genetic composition of a pop across generations |
| How does gene flow lead to evolutionary changes in a population? | movement of alleles from one population to another |
| How do mutations lead to evolutionary change in a population? | a random, unpredictable change in DNA |
| what is stablilizing selection? | it selects against phenotypic extremes and favors the mean |
| how does stabilizing selection effect populations? | since individuals in the middle are favored the bell curve narrows in the population |
| What is directional selection? | favors an extreme phenotype at one end of the normal distribution |
| How does directional selection effect populations? | since individuals at one extreme are more favored the Bell curve shifts to the right or to the left |
| What is disruptive selection? | favors two or more extreme phenotypes at the expense of the mean |
| How does disruptive selection effect populations? | since normal phenotype is selected against and more than one alternative phenotype is favored the curve is bimodal |
| What is the Founder's effect? | genetic drift that results from a small population colonizing a new area |
| What is the Bottleneck effect? | rapid, significant decrease in population size due to chance event |
| What is the Hardy-Weinburg principle? | frequencies of alleles and genotypes in a population do not change from generation to generation unless influenced by outside forces |
| What are the five assumptions of the Hardy-Weinburg equilibrium? | no selection, no mutation, no migration, large population, and random mating |
| What are the three modes of selection? | stabilizing, directional, and disruptive |
| what is the importance of mutations from a evolutionary standpoint? | mutations are the ultimate source of genetic variation |
| what is the importance of genetic variation from a evolutionary standpoint? | Genetic variation is the raw material for evolutionary change |
| what are prezygotic barriers? | reproductive isolating mechanisms that prevent fertilization from taking place |
| what are post zygotic barriers? | reproductive isolating mechanisms that increase the likelihood of reproductive failure if fertilization does occur |
| what is allopatric speciation? | evolution of a new species after populations have been seperated geographically, preventing gene flow |
| what is sympatric speciation? | evolution of new species in populations that live in the same geographic area |
| What is a hybrid zone? | area of overlap between two recently diverged populations in which interbreeding takes place and hybrid offspring are common |
| what are the possible outcomes for a hybrid zone? | reinforcement of barriers, fusion of species , stability of hybrid zone |
| What is the Morphological species concept? | organisms are classified into separate species based on visible structural differences |
| what are the limits of the morphological species concept? | closely related species may be morphologically similar, single spp. may have several varieties with morphological differences and it relies on subjective criteria |
| what is the biological species concept? | species are groups of actually potentionally interbreeding natural populations that are reproductively isolated from such other groups |
| what are the limits of the biological species concept? | not all organisms interbreed and sometimes barriers to inter-species breeding aren't strong |
| what is the phylogenetic species concept? | species are the smallest possible group decsending from a common ancestor and recognizable by unique traits |
| what are the limits of the phylogenetic species concept? | requires access to expensive lab equipment, and if used exclusively brings the addition of 100s to 1000s of new species |
| what is habiat isolation ? | diff species in the same geographic area are reproductively isolated due to living/breeding in diff habitats |
| what is temporal isolation ? | a difference in reproductive timing prevents two species from reproducing |
| What is behavioral isolation? | species specific courtship behaviors different species from reproducing |
| what is mechanical isolation? | structural differences in reproductive organs prevent different species from successfully mating |
| what is gametic isolation? | molecular and chemical differences cause egg and sperm of different species to be incompatible |
| what is hybrid inviability? | embryo with parents from two different species fails to develop properly |
| what is hybrid sterility? | problems during meiosis cause the gametes of a interspecific hybrid to be abnormal |
| what is the order of the taxonomic classification system? | domain kingdom phylum class order family genus species |
| what is phylogeny? | the evolutionary history of a species or group of related species |
| what is homology? | phenotypic and genetic similarities due to shared common ancestry |
| what is analogy? | similar features that evolved independently and not due to common ancestry |
| what is a monophyletic group? | includes the ancestral species and all descendants |
| what is a paraphyletic group? | includes the common ancestor and some, but not all, descendants |
| what is a polyphyletic group? | includes distantly related species but does not include the most recent common ancestor |
| what is a derived trait? | evolutionary novelty unique to particular clade |
| what is a ancestral trait? | originated in an ancestor of the taxon |
| What is the possible structure of the tree of life? | three domain system |
| what is horizontal gene transfer? | transfer of genes from genome of one species to anothers |
| what is horizontal gene transfer's impact on evolutionary history? | likely common in early history of life |
| what are fossils? | reveals evolutionary history of life on earth |
| how are fossils dated? | relative dating and radiometric dating |
| what can the fossil reveal about life's history? | it reveals the evolutionary history |
| what are the consequences of plate tectonics on life on earth? | when plates separate, slide pass each other, or collide earthquakes, formation of mountains, islands, and seas are formed |
| what are the consequences of mass extinctions? | can take 10-100 million years for diversity to recover, alter ecological communities, curtail lineages with novel and advantageous traits, leads to adaptive radiations |
| what are the factors that promote adaptive radiation? | mass extinctions, evolution of novel characteristics , and colonization of new regions |
| How do new body forms originate by heterochrony? | evolutionary change in rate or timing of developmental events |
| how do new body forms can originate by paedomorphosis? | rate of reproductive development accelerates compared to somatic development |
| how do new body forms originate through alterations of Hox genes or gene? | master regulatory genes that determine organization/position of body structures during development |
| how does the concept of descent with modification applies to the evolution of complex structures? | natural selection only improves a structure in the context of it's current utility |
| what is relative dating? | the age of rocks and fossils are determined by sequence in rock strata |
| what is radiometric dating? | age of rocks and fossils determined by decay of radioactive isotopes |
| how are fossils formed? | layers of sedimentary rock over an organism |
| what are stromatolites? | the oldest known fossils |
| what is the great oxgenation event? | early prokaryotes released oxygen into atmosphere via photosynthesis |
| what did eukaryotes originate? | 1.8 billion yrs ago |
| what is the consequence of continental drift? | allopatric speciation, distribution of fossils and living groups |
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