Evolutionary Genetics and Population Dynamics, Exams of Biology

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LSU BIOL 1202 Biology for Science Majors II Hrincevich Exam 1 actual written questions and answers complete exam update Louisiana State University A new era of biology began in 1859 when Charles Darwin published The Origin of Species, which focused on the - ANSWER great diversity of organisms Evolution can be defined by Darwin's phrase - ANSWER descent with modification Evolution can be viewed as both a - ANSWER pattern and a process Darwin's ideas had - ANSWER deep historical roots The Greek philosopher Aristotle viewed species as fixed and - ANSWER arranged them on a scala naturae The Old Testament holds that species were individually - ANSWER designed by God and therefore perfect Carolus Linnaeus interpreted organismal adaptations as evidence that the creator had designed each species for a - ANSWER specific purpose Linnaeus was the founder of taxonomy, the branch of biology concerned with - ANSWER classifying organisms He developed the binomial format for - ANSWER naming species The study of fossils helped to lay the - ANSWER groundwork for Darwin's ideas Fossils are remains or traces of organisms from the past, usually found in sedimentary rock, which appears in - ANSWER layers called strata Paleontology, the study of fossils, was largely developed by - ANSWER French scientist Georges Cuvier Cuvier speculated that the boundaries between strata represent - ANSWER catastrophic events Geologists James Hutton & Charles Lyell thought that changes in Earth's surface resulted from slow, steady actions still - ANSWER operating today at the same rate This view strongly - ANSWER influenced Darwin's thinking French biologist Jean-Baptiste de Lamarck hypothesized that species evolve through use and disuse of - ANSWER body parts and the inheritance of acquired characteristics Proposed mechanisms are - ANSWER unsupported by any scientific evidence Darwin reasoned that large morphological gaps between related groups could be explained by - ANSWER branching process and past extinction events Darwin noted that humans have modified other species by selecting and breeding individuals with desired traits, a - ANSWER process called artificial selection Darwin drew two inferences from two observations: Observation 1: members of a population ____ Observation 2: all species can produce more offspring than the environment can support, and ____ - ANSWER often vary in their inherited traits, many of these offspring fail to survive and reproduce Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to - ANSWER leave more offspring than other individuals The unequal ability of individuals to survive and reproduce will lead to the accumulation of - ANSWER favorable traits in the population over generations Darwin was influenced by Thomas Malthus, who noted the potential for the human population to increase faster than - ANSWER food supplies and other resources If some heritable traits are advantageous, individuals with these traits will produce more offspring that survive to reproduce, and this will increase the frequency of - ANSWER these traits in the next generation This process increases the frequency of individuals with favorable adaptations and explains how organisms become increasingly well - ANSWER suited for life in their environment Individuals with certain heritable traits survive and reproduce at - ANSWER a higher rate than other individuals Natural selection increases the frequency of adaptations that are - ANSWER favorable in a given environment If an environment changes over time, natural selection may result in adaptation to these new conditions and may - ANSWER give rise to new species Individuals do not evolve, rather - ANSWER populations evolve over time Natural selection can only increase or decrease - ANSWER heritable traits that vary in a population New discoveries continue to fill the - ANSWER gaps identified by Darwin in The Origin of Species Four types of data document the pattern of evolution - ANSWER direct observations, homology, the fossil record, biogeography Two examples provide evidence for natural selection: natural selection in response to introduced species and the - ANSWER evolution of drug-resistant bacteria Soapberry bugs use their "beak" to - ANSWER feed on seeds within fruits Feeding is most effective when beak length is closely matched to - ANSWER seed depth within the fruit In southern florida, they feed on the native balloon vine with larger fruit, they have - ANSWER longer beaks in central florida, they feed on the introduced goldenrain tree with smaller fruit; they have - ANSWER shorter beaks One strain of Staphylococcu aureus (MRSA) is - ANSWER a dangerous pathogen Resistance to penicillin evolved in S. aureus by - ANSWER 1945, two years after it was first widely used Resistance to methicillin evolved in S. aureus by 1961, - ANSWER two years after it was first widely used Natural selection does not create new traits, but edits or selects for traits - ANSWER already present in the population Evolution by natural selection can occur rapidly in species with - ANSWER short generation times The current, local environment determines which traits will be selected for or - ANSWER against in any specific population Evolution relies on mutations, or - ANSWER changes in DNA sequences Mutations can be single nucleotides all the way through - ANSWER loss/gain of entire chromosomes similarity resulting from common ancestry - ANSWER homology New alleles arise by mutation, a change in the - ANSWER nucleotide sequence of DNA New genes and alleles can arise by - ANSWER gene duplication Sexual reproduction can result in genetic variation by - ANSWER recombining existing alleles Only mutations in cells that produce gametes can be - ANSWER passed to offspring A point mutation is a change in a single nucleotide in a - ANSWER DNA sequence Point mutations in non-coding regions (introns) generally result in neutral variation, conferring no selective - ANSWER advantage or disadvantage Mutations to genes can be neutral because of - ANSWER redundancy in the genetic code Chromosomal mutations that delete, disrupt, or rearrange - ANSWER many loci are typically harmful Duplication of small pieces of DNA increases genome - ANSWER size and is usually less harmful Mutation rates are low in animals and plants. The average is about one mutation in every - ANSWER 10,000 genes per generation Viruses have both high mutation rates and - ANSWER short generation times In organisms that reproduce sexually, most genetic variation results from - ANSWER recombination of alleles Sexual reproduction can shuffle existing alleles into new combinations through three mechanisms: - ANSWER crossing over (accounts for most of the variation), independent assortment (random alignment and separation of chromosomes), fertilization Genetic variation is required for a population to evolve, but does not guarantee that it will. One or more factors that cause evolution must be at work for - ANSWER a population to evolve Populations are not always geographically isolated, but individuals typically only breed with - ANSWER members of their own population A locus is fixed if all individuals in a population are - ANSWER homozygous for the same allele p - ANSWER dominant q - ANSWER recessive In a population where gametes contribute to the next generation randomly and Mendelian inheritance occurs, allele and genotype frequencies remain constant from generation to generation. Such a population is in - ANSWER HW equilibrium If the observed genetic makeup of the population differs from expectations under HW, it suggests that the - ANSWER population may be evolving Conditions for HW - ANSWER no mutations, random mating, no natural selection, large population size, no gene flow Three major factors alter allele frequencies and bring about most evolutionary change: - ANSWER natural selection, genetic drift, gene flow Natural selection can cause adaptive evolution, a process in which traits that enhance survival or reproduction - ANSWER increase in frequency over time The smaller a sample, the greater the chance of random - ANSWER deviation from a predicted result Two main types of genetic drift - ANSWER founder effect, population bottleneck The founder effect occurs when a few individuals become isolated from a larger population or leave - ANSWER a population and move to a new area Allele frequencies in the small founder population can be different from - ANSWER those in the larger parent population The bottleneck effect occurs when there is a drastic reduction in population size due to - ANSWER a sudden change in the environment The resulting gene pool may no longer be reflective of the - ANSWER original population's gene pool Understanding the bottleneck effect can increase understanding of how - ANSWER human activity affects other species Genetic drift is - ANSWER significant in small populations Genetic drift can cause allele frequencies to - ANSWER change at random Genetic drift can lead to a loss of - ANSWER genetic variation within populations Behavioral isolation - ANSWER Courtship rituals and other behaviors unique to a species are effective barriers Mechanical isolation - ANSWER morphological differences prevent successful mating Gametic isolation - ANSWER Sperm of one species may not be able to fertilize eggs of another species Postzygotic barriers prevent the hybrid zygote from developing into a viable, fertile adult by - ANSWER reduced hybrid viability, reduced hybrid fertility, hybrid breakdown reduced hybrid fertility - ANSWER Even if hybrids are vigorous, they may be sterile reduced hybrid viability - ANSWER genes of the different parent species may interact and impair the hybrid's development or survival in its environment hybrid breakdown - ANSWER some first generation hybrids are fertile, but when they mate with each other or with either parent species, offspring of the next generation are feeble or sterile morphological species concept - ANSWER defines a species by structural features ecological species concept - ANSWER defines a species in terms of its ecological niche gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations - ANSWER allopatric speciation speciation occurs in populations that live in the same geographical area - ANSWER sympatric speciation Sympatric speciation can occur if gene flow is reduced by factors including - ANSWER polyploidy, sexual selection, habitat differentiation Polyploidy is the presence of extra sets of chromosomes due to - ANSWER accidents during cell division An allopolyploid is a species with multiple sets of chromosomes derived from - ANSWER different species Allopolyploids can successfully mate with each other, but cannot - ANSWER interbreed with either parent species A hybrid zone is a region in which members of a different species - ANSWER mate and produce hybrids Hybrids often have reduced fitness vs. - ANSWER parent species If hybrids do not become reproductively isolated from their parent species, then three alternate outcomes are possible - ANSWER reinforcement, fusion, stability reinforcement - ANSWER strengthening reproductive barriers fusion - ANSWER weakening reproductive barriers stability - ANSWER continued formation of hybrid individuals Punctuated equilibria describes these periods of apparent stasis - ANSWER punctuated by sudden change happens on a scale that transcends the boundaries of a single species - ANSWER macroevolution