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Ecology and Evolutio
Bio 1101
| Question | Answer |
|---|---|
| What is evolution? | Change in the gene pool (alleles) over time |
| What is microevolution? | Change in allelic frequencies of a population over time |
| Mechanisms by which microevolution occurs: | Mutation, migration, genetic drift, sexual selection, natural selection |
| What is macroevolution? | Processes resulting in origin of new taxonomic groups |
| Can microevolution result in macroevolution? | Yes |
| The broad pattern of evolution... | Is macroevolution |
| What is a localized group of individuals capable of interbreeding and producing fertile offspring? | A population |
| At which level is evolution observed? | Population level |
| (blank) is a result of both genetics and environment. | Variation |
| What are mutations? | Change in the nucleotide sequence of an organism's DNA |
| Are mutations random? | Yes |
| Where must mutations occur to have evolutionary impact? | Gamete cell lines |
| What are the fates of mutation? | Harmful, neutral, or beneficial |
| When observed at population level, what might mutations affect? | The gene pool |
| What is the gene pool? | Genetic composition of a population |
| How can mutations accumulate more quickly? | Short generation times/rapid reproduction |
| What effect does sexual reproduction have on existing alleles? | It shuffles them into new, unique combinations (crossing over or independent assortment) |
| Our current understanding of variation, inheritance, and evolution are a result of what? | The modern synthesis |
| What is the modern synthesis? | Combining Darwin and other evolutionary biologists' ideas with genetics and molecular biology |
| What is differential reproductive success? | Favorable alleles are passed on to next generations in proportions that differ from present generations |
| How did Darwin travel? | On the HMS Beagle, mapping the coastline of S. America (especially the Galapagos islands) |
| What ideas did Darwin start to explore in the Voyage of the Beagle? | He correlated the shape of finch beaks with the type of food they eat |
| What did Darwin conclude about the environment and origin of species? | That they were closely related processes |
| What did Darwin conclude after reading Malthus? | Some aspects of the environment act as selective agents |
| Why was the Origin of Species published early? | It was a response to Alfred Wallace's work |
| What did the Origin of Species go over? | Descent with modification, proposed natural selection as a mechanism for biological evolution, and used artificial selection to support his arguments |
| In order for natural selection to occur... | Variation needs to be present in a population, that variation needs to be heritable, and species should produce more offspring than the environment can support |
| Natural selection is... | A heritable trait must be variable in a population, and that population must be under competition pressure |
| What inferences come from natural selection? | Some individuals are more likely to survive and reproduce, and this differential survivability leads to the accumulation of favorable traits in the population over generations |
| What is directional selection? | An extreme phenotype is favored and distribution curve shifts in that direction |
| Where is directional selection common? | Environments that undergo fluctuations or where migration is common (e.g. black bears, Galapagos finches, peppered moths) |
| What is disruptive selection? | Two or more extreme phenotypes are favored over an intermediate (e.g. African swallowtails) |
| What is stabilizing selection? | An intermediate phenotype is favored (e.g. gall size, human birth rates) |
| What does natural selection promote when a match between a species and its environment increases? | Adaptive evolution |
| What do we know about adaptive evolution? | It is the only mechanism of evolution that consistently improves the match between organisms and their environments, is a continuous process, and selection can only act on existing variations |
| Are adaptations often compromises? | Yes |
| What is genetic drift? | Unpredictable change in alleles frequency due to chance; more likely in smaller populations |
| What are some common effects of genetic drift? | Decreases genetic variation/diversity as alleles become fixed |
| What is the founder effect? | A few individuals become isolated from a larger population and establish a new population whose gene pool differs from the source population (e.g., Retinitis Pigmentosa on the island) |
| What is the bottleneck effect? | Size of population is reduced by a sudden change in the environment and the surviving gene pool differs from the original population |
| What happens to genetic diversity after a population recovers from the bottleneck effect? | Genetic diversity decreases |
| What is gene flow? | Transfer of alleles into/out of a population due to movement of fertile individuals or gametes sentiment |
| How does gene flow homogenize subpopulations? | It reduces variation among populations |
| What is sexual selection? | Natural selection related to mating success because |
| What is sexual dimorphism? | Marked differences between sexes as a result of sexual selection |
| What does sexual selection frequently result in? | Competition or choosy behavior |
| What is intrasexual selection? | Individuals of one sex (usually males) compete for mates of the opposite sex |
| What are the types of competition in intrasexual selection? | Direct (aggressive) and indirect (ritualized displays) competitions |
| What is intersexual selection? | Individuals of one sex (usually female) are choosy in selecting mates |
| How do individuals choose mates in intersexual selection? | Showiness of appearance or behavior (poses a survival risk; trade-off) |
| What is the evolution of elaborate characters in sexual selection? | Sexy Sons and Good Genes Hypothesis |
| What is the Sexy Sons Hypothesis? | Focuses on attractiveness and reproductive success of sons |
| What is the Good Genes Hypothesis? | Focuses on viability and reproductive success of both sons and daughters |
| How can mechanisms counteract one another? | Natural selection can negate gene flow, gene flow can counteract effects of genetic drift |
| When was the Bent grass's adaptation against copper disadvantageous? | It lowered reproductive success in low copper areas (present due to wind pollination: gene flow but did not persist due to natural selection) |
| When did gene flow counteract genetic drift? | Greater Prairie Chickens in Illinois |
| How did gene flow counteract genetic drift with the Prairie Chickens? | Their genetic variation was low and most eggs weren't hatching (genetic drift) until new alleles were artificially introduced (gene flow) |
| What is species concept? | How biologists define a species; no one definition of species is universally accepted or applicable |
| How is Biological species defined? | Reproductive compatibility |
| How is Morphological species defined? | Physical features |
| How is Phylogenetic species defined? | Evolutionary relationship |
| What are the attributes/limitations of Biological species? | Emphasizes gene flow; not applicable to all organisms |
| What is allpoatric speciation? | Geographic isolation; divergence; secondary contact |
| In allopatric speciation, how can isolation occur? | Vicariance (splitting of a population), or dispersal |
| In allopatric speciation, how can divergence occur? | Natural selection, genetic drift, mutation, or sexual selection |
| What is an example of allopatric speciation? | Bahama mosquito fish; high versus low predation pools and females chose their own |
| What is sympatric speciation? | Speciation occurs in geographic range of parent population- Gene flow limited; divergence; secondary contact |
| In sympatric speciation, what is gene flow limited by? | Genetic, habitat, and/or behavioral isolation |
| In sympatric speciation, what are divergence factors? | Natural selection, mutation, sexual selection, and |
| What is an example of sympatric speciation? | Goatsbeard plants; hybrids are viable and unable to mate with either parental species |
| What is maintaining species barriers? | In order to have species form and remain distinct there has to be reproductive isolation |
| What is reproductive isolation? | Existence of factors (barriers) that impede interbreeding and/or population of fertile offspring |
| What are prezygotic barriers? | Habitat isolation; same geographic area but different habitats, timing, or mating rituals (e.x., seabirds with their lice, Blue-footed boobie mating dance, cicadas) |
| What are postzygotic barriers | Hybrids form but do not persist |
| In postzygotic barriers, what is reduced hybrid viability? | Does not survive past embryonic stage or is too frail to persist (e.g., Rana frogs) |
| In postzygotic barriers, what is reduced hybrid fertility? | Hybrid survives, but unsterile and usually produces abnormal gametes (e.g., mules) |
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