Bio Vocab Exam 4/24
About this set
Created by:
kris10dulce on April 24, 2012
Log in to favorite or report as inappropriate.
Order by
76 terms
Terms | Definitions |
|---|---|
 Adaptations | inherited characteristics that enhance an organism's ability to survive and reproduce in a particular environment. According to Darwin's theory of evolution, living species are descended from earlier life-forms that differed from present day organisms |
| Descent with modification | Darwin's theory, which explains that all of life is connected by common ancestry and that descendants have accumulated adaptions to changing environments over vast spans of time. Drwin's theory differed greatly from the long-held notion of o young Earth inhabited by unchanging species |
| Evidence of evolution | Natural Selection has been observed in populations of birds, insects and many other organisms. The fossil record reveals the historical sequence in which organisms have evolved and many fossils linking ancestral species with those living today. Further evidence for evolution comes from biogeography, comparative anatomy, and molecular biology. Homologous structures and DNA sequences provide evidence of evolutionary relationships |
| Evolutionary trees | diagrams based on homologies that reflect the evolutionary relationships among groups of organisms |
| Populations evolve | Microevolution is a change in the relative frequencies of alleles in a population's gene pool |
| Genetic variation | generated by mutation and sexual reproduction. Mutations are important in the adaption of prokaryotes to the environment. In diploid organisms, the shuffling of alleles in sexual reproduction provides most variation. |
| Allele frequencies | change due to natural selection (reproductive success of individuals best suited to the environment), genetic drift (change in a gene pool due to chance), and gene flow (movement of individuals or gametes between populations). The bottleneck effect and founder effect lead to genetic drift. |
| Fitness | relative contribution an individual makes to the gene pool of the next generation. As a result of natural selection, favorable traits increase in a population. |
| Sexual Selection | leads to the evolution of secondary sex characteristics, which can give individuals an advantage in mating |
| Antibiotic resistance | bacteria illustrates directional selection resulting from excessive or incorrect use of antibiotics |
| preservation of variation | Diploidy preserves variation by "hiding" recessive alleles. Balancing selection may result from heterozygote advantage or frequency-dependent selection |
| Perfect organisms? | Natural selection can act only on available variation; anatomical structures result from modified ancestral forms; adaptions are often compromises; and chance, natural selection, and environment interact 1. selection can act only on existing variations 2. evolution is limited by historical constraints 3. adaptations are often compromises 4. Chance, natural selection, and the environment interact |
| artificial selection | The selective breeding of domesticated plants and animals to promote the occurrence of desirable traits |
| natural selection | 1. editing proces than a creative mechanism 2. contingent on time and place; favors those characteristics in a varying population that fit the current, local environment -not part of Hardy-Weinberg equilibrium: populations consist of varied individuals, and some variants leave more offspring than others -improves the match between organisms and their environment |
| extinction | the irrevocable loss of a species |
| evolution by natural selection | 1. individuals do not evolve; it's by generation to generation 2. natural selection can only amplify or diminish heritable traits 3. evolution is not goal directed; it does not lead to perfectly adapted organisms. NAtural selection is the result of environmental factors that vary from place to place and from time to time |
| paleontologists | a scientist who studies fossils |
| fossils | -A preserved remnant or impression of an organism that live in the past -can tell age by the layers of rock -often replicas |
| Trace fossils | footprints, burrows and other remnants of ancient organism's behavior |
| fossil record | THe chronicle of evolution over millions of years of geologic time engraved in the order in which fossils appear in rock strata |
| strata | Rock layers formed when new layers of sediment cover older ones and compress them |
| Biogeography | -organisms evolve from ancestral species |
| Comparative Anatomy | -anatomical similarities between many species give signs of common descent -homology -illustrates that evolution is a remodeling process in which ancestral structures that originally functioned in one capacity become modified as they take on new functions -vestigial organs |
| homology | Similarity in characteristics resulting from a shared ancestry |
| homologous structures | Structures in different species that are similar because of common ancestry |
| vestigial organs | A structure of marginal or no importance to an organism. Vestigial organs are historical remnants of structures that had importan function in ancestors |
| Molecular biology | -sequences must have been inherited from a relatively recent common ancestor -the greater number of sequence differences between species, the more distant is their last common ancestor |
| evolutionary tree | -hypotheses reflection our current understanding of patterns of evolutionary descent |
| gene pool | All the alleles for all the genes in a population |
| microevolution | A change in a population's gene pool over generations |
| Genetic Variation | -molecular level -not all variation in a population is heritable -only genetic component of variation is relevant to natural selection |
| Mutation | -definition: change in the nucleotide sequence of DNA -new alleles originate -ultimate source of genetic variation that serves as raw material for evolution -a mutation that substitutes one nucleotide for another will be harmless; however if it does affect the protein's function, the mutation will probably be harmful -mutant allele may actually improve the adaptation of an individual to its environment and enhance its reproductive success -chromosomal mutations that delete, disrupt, or rearrange many gene loci at once are most certain to be harmful; but duplication of part of chromosome is an important source of genetic variation -prokaryotes: can generate genetic variation |
| Sexual Reproduction | -a genetic variation in a population results from the unique combination of alleles that each individual inherits |
| genetic drift | -a change in the gene pool of a population due to chance -tends to reduce genetic variation through losses through natural disasters -bottleneck effect--> can continue on for genertions -founder effect |
| bottleneck effect | GEnetic drift resulting from a drastic reduction in population size; typically, the surviving population is no longer genetically representative of the original population |
| founder effect | Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the composition of the new population's gene pool is not reflective of that of the original population |
| fitness | -genes |
| phenotype | -physical traits -reliant on environment |
| stabilizing selection | -favors intermediate phenotypes |
| directional selection | -shifts the overall makeup of the population by acting against individuals at one of the phenotypic extremes -most common during periods of environmental change or when members of a species migrate to some new habitat with different environmental conditions |
| Disruptive selection | -occurs when environmental conditions are varied in way that favors individuals at both extremes of a phenotypic range -can lead to two or more contrastinc phenotypes in a population |
| sexual dimorphism | Marked differences between the secondary sex characteristics of males and females |
| sexual selection | A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates. |
| intrasexual selection | -type of sexual selection in which could involve physical combat, but are more often ritualized displays -common in species where the winning individual garners a harem of mates |
| intersexual selection | -between sexes or mate choice -individuals of one sex are choosy in selecting their mates |
| antibiotics | -drugs that kill infectious microorganisms -an adaption that helps them destroy bacteria that compete with them for space and nutrients |
| Balancing selection | Natural selection that maintins stable frequencies of two or more phenotypic forms in a population |
| heterozygote advantage | Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools |
| Frequency-dependent selection | A decline in the reproductive success of individuals that have a phenotype that has become too common in a population |
| neutral variation | Genetic variation that does not appear to provide a selective advantage or disadvantage |
| Taxonomy | The branch of biology that identifies, names, and classifies species |
| species | kind or appearance |
| biological species concept | -defines a species as a group of populations whose members have the potential to interbreed in nature and produce fertile offspring -reproductive isolation -not able to tell if the fossils were able to interbreed -useless for organisms such as prokaryotes that are asexual in their reproduction |
| reproductive isolation | The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids |
| Other Definitions of Species | -classification is based mainly on observable and measurable physical traits such as shape, size, and other features of morphology (form) -morphological species concept -ecological species concept |
| morphological species concept | -advantage: can be applied to asexual organisms and fossils does not require information on possible interbreeding -disadvantage: relies on subjective criteria, and researchers may disagree on which structural features distinguish a species |
| ecological species concept | A definition of species in terms of ecological roles |
| phylogenetic species concept | A definition of species as the smallest group of individuals that shares a common ancestor and forms one branch on the tree of life |
| reproductive barrier | A biological feature of a species that prevents it from interbreeding with other species even when populations of the two species live together |
| prezygotic Barriers | -prevent mating or fertilization between species -temporal isolation: species breed at different times -habitat isolation: two species live in the same general rea but not in the same kinds of places -behavioral isolation: no sexual attraction between females and males of different species -mechanical isolation: when female and male organs are compatible -gametic isolation: male and female from two different species may copulate, but the gametes do not unite to form a zygote |
| Postzygotic Barriers | -operate after hybrid zygotes are formed -reduced viability: hybrid offspring do not survive -reduced hybrid fertility: hybrid offspring of two different species reach maturity and are vigorous but sterile, and therefore unable to bring about gene flow between the parent species -hybrid breakdown: first-generation of hybrid offspring are viable and fertile, but when these hybrids mate with one another or with either parent species, the offspring are feeble or sterile |
| sympatric speciation | occurs when a new species originates while remaining in a geographically overlapping area with the parent species. Many plant species have evolved by polyploidy (duplications of the chromosome number due to the errors in cell division). Many plants, including food plants such as bread whetat are the result of hybridication and polyploidy. Habitat differentiation and sexual selection (usually involving mte choce) can also result in sympatric speciation) |
| polyploid | -cells have more than two complete sets of chromosomes 1. a failure of cell division after chromosome duplication could double a cell's chromosomes 2. if this 4n cell gives rise to a tetraploid branch, flowers produced on this branch would produce diploid gametes 3. if self fertilization occurs the resulting tetraploid zygotes may develop into plants that produce fertile tetraploid offspring by self-pollination or by mating with other tetraploids -arise from hybridization of two different species |
| triploid individuals | sterile |
| hybridization | 1. haploid gametes from two different species combine, the resulting hybrid is normally sterile because its chromosomes cannot pair during meiosis 2. however, the hybrid may reproduce asexually 3. subsequent errors in cell division may produce chromosome duplications that result in a fertile polyploid species -between two species accounts for most of these species, perhaps because of the adaptive advantage of the diverse genes a hybrid inherits from different parental species |
| hybrid zones | regions in which members of different species overlap and produce at least some hybrid offspring. over time, reinforcement may strengthen prezygotic barriers to reproduciton, or fusion may reverse the speciation process as reproductive barriers weaken and extensive gene flow occurs. In stable hybrid zones, a limited number of hybrid offspring continue to be produced |
| reinforcement | -hybrids are less fit than members of both parent species, we might expect natural selection to strengthen or reinforce reproductive barriers -overlap in populations -isolated by female mate choice based on male coloration |
| Stability | -many hybrid zones turn out to be fairly stable in the sense that hybrids continue to produce |
| adaptive radiation | can occur when populations are provided with expanded opportunities following mass extinctions, the colonization of a diverse new environment, or the evolution of new structures |
| punctuated equilibria | In the fossil record, long periods of apparent stasis in which a species undergoes little or no morphological change interrupted by relatively brief periods of sudden change |
| speciation | the origin of new species connects microevolution and macroevolution and has led to earth's incredible biological diversity |
| defining species | Linnaeus used physical characteristics to distinguish species. His binomial system is the basis of taxonomy; the naming and classification of life's forms. The biological species concept defines a species as group of populations whose members can interbreed and produce fertile offspring with each other but not with the members of other phenotypic traits--the morphological species concept. THe ecological species concept defines a species by its ecological is the smallest group that shares a common ancestor and forms one branch of the tree of life |
| reproductive barriers | serve to isolate a species gene pool and prevent interbreeding |
| allopatric speciation | geographically separated from other populations, a small population may become genetically unique as its gene pool is changed by natural selection, mutation, or genetic drift |
| evolution of reproductive barriers | a laboratory study has documented the beginning of reproductive isolation as fruit fly populations adapted to a new food source. Researches have identified the specific genes involved in some cases of speciation |
| speciation rates | the punctuated equilibrium model draws on the fossil record, where many species change most as the arise form an ancestral species and then change relativel little for the rest of their existence. but some species have evolved by the gradual accumulation of changes. the time interval between speciation events varies considerably, from a few thousand years to tens of millions of years |
First Time Here?
Welcome to Quizlet, a fun, free place to study. Try these flashcards, find others to study, or make your own.