Biology 1001 Key Terms Ecology & Evolution

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BIOL 1001
Dr.Stephen Yezerinac

Biology 1001-Ecology, Evolution and Diversity Cydney Kane heredity: the transmission of traits from one generation to the next variation: the change in inherited genetic material genetics: the scientific study of heredity and variations genes: encoded information that is passed from parent to offspring gametes: reproductive cells that hold genetic information somatic cells: all cells in the body excluding gametes and their precursor locus: a gene's specific location on a chromosome clone: a group of genetically identical individuals karyotype: a display of condensed chromosomes arranged in pairs homologous chromosomes: two paired chromosomes containing the same genes sex chromosomes: the X and Y chromosomes autosomes: chromosomes other than the X and Y chromosomes diploid cells: any cell with two chromosome sets (2N) haploid cells: cells that contain a single set of chromosomes, gametes (N) zygote: fertilized egg cell meiosis: cellular division that results in the creation of gametes alternation of generation: plants with sporophytes and gametophytes evolution: descent with modification over several generations strata: new layers of sediment cover older ones and compress them into superimposed layers of rock creating fossils palaeontology: study of fossils catastrophism: the principle that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present uniformitarianism: the same mechanisms of change are constant over time adaptations: inherited characteristics of organisms that enhance their survival and reproduction in specific environment natural selection: a process in which individuals that certain inherited traits tend to survive and reproduce at higher rates than other individuals because of these traits artificial selection: the purposeful breeding of individuals that possess certain desired traits Basis of Darwin's argument: observation #1: members of a population often vary in their inherited traits observation #2: all species can produce more offspring than their environment can support, and many of those offspring fail to survive and reproduce inference #1: individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals inference #2: this unequal ability of individuals to survive and reproduce will lead to the accumulation of favourable traits in the population over generations homology: similarities resulting from a common ancestors homologous structures: structures that represent variation on a structured theme that was present in a common ancestor vestigial structures: remnants of features that served important functions in the organisms' ancestors, but no longer serve a purpose evolutionary tree: a diagram that reflects evolutionary relationships among groups of organisms convergent evolution: the independent evolution of similar features in different lineages analogous: when species have an evolutionary trait in common, we deem it to be analogous biogeographical: the geographical distribution of species endemic: when a species is found nowhere else in the world microevolution: a change in allele frequencies in a population over generations genetic variation: differences among individuals in the composition of their genes or other DNA segments average heterozygotes: the average percentage of loci that are heterozygous geographical variation: differences in genetic composition of separate population based on geographical distribution cline: a graded change in character along a geographical axis sources of genetic variation: formation of new alleles: change in nucleotide sequence altering gene number or position: when loci rearrange, typically is harmful rapid reproduction: how often an organism passes to the next generation increases the likelihood of mutation sexual reproduction: variation occurs due to the variation in genotype from meiosis population: a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring gene pool: all copies of every type of allele at every locus in all members of the population Hardy-Weinberg principle: where p + q = 1 p + 2pq + q = 1 assumptions: • no mutations occur • random mating must occur • no natural selection occurs • a large population size exists • no migration takes place genetic drift: the fluctuation of alleles from one generation to the next founder effect: when a few individuals become isolated from a larger population. This smaller group may establish a new populations whose gene pool differs from the original population bottleneck effect: a severe reduction in size of a population changing the allele frequencies gene flow: the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes relative fitness: the contribution an individual makes to the gene pool of the next generation relative to the contribution of others directional selection: when conditions favour individuals exhibiting one extreme of a phenotypic range, thereby shifting a population's frequency curve for the phenotypic character in one direction or the other disruptive selection: when conditions favour individuals at both extremes of a phenotypical range stabilizing selection: acts against both extreme phenotypes and favours intermediate variants sexual selection: the probability of obtaining a mate sexual dimorphism: difference between the two sexes in secondary sexual characters neutral variation: differences in DNA sequences that offer no distinct advantage or disadvantage balancing selection:
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