Midterm

Cards (62)

  • An individual's evolutionary fitness is measured by it's ability to reproduce.
  • Darwin's theory proposed that organisms with heritable traits that favor survival and reproduction will tend to leave more offspring than their peers. This causes the traits to increase in frequency over generations.
  • Variation refers to differences among individuals within a population. These variations are often due to genetic differences between individuals.
  • Vestigial structures: a feature that a species inherits from its ancestors but is no longer used
  • Homologous traits : When organisms share a trait due to common ancestry 
  • Analogous traits : when two or more different groups have similar features, but they did not evolve from a shared ancestor
  • Example of a homologous trait : all vertebrate animals (frogs, birds, fish, people) have skeletons because the ancestor of the vertebrates had a skeleton and passed that trait on to all of its descendants.
  • Example of an analogous trait : wings evolved independently in bats and birds, so while both have wings, it was not inherited from a common ancestor.
  • What are the different evolutionary forces : natural selection, genetic drift, gene flow, mutation
  • Natural Selection : The process by which individuals with advantageous traits survive and reproduce at higher rates than those without them
  • Genetic Drift : A change in allele frequency within a population caused by chance events such as random sampling during reproduction
  • Gene Flow : Movement of genes between populations through migration
  • Mutations : Changes in DNA sequence that can be beneficial, detrimental, or neutral
  • Evolution is driven by changes in allele frequencies over time
  • Allopatric speciation refers to the formation of new species when a population is geographically isolated from the parent population
  • Sympatric speciation occurs when two or more reproductively isolated lineages coexist in the same area
  • The Hardy-Weinberg principle states that if certain conditions are met (no mutation, no gene flow, large population size, random mating), then allele frequencies will remain constant from one generation to the next.
  • The process of sympatric speciation involves genetic divergence without physical isolation.
  • Biological species concept: A species is a group of populations whose members have the potential to interbreed in nature and produce fertile offspring.
  • Gene flow occurs between the different populations of a species. This ongoing exchange of alleles tends to hold the populations together genetically. 
  • Population refers to the total number of individuals of a species in a particular area at a given time.
  • Two Reproductive Isolating Mechanisms involve the zygotes these are : Prezygotic and Postzygotic
  • Prezygotic barriers refer to the impeding of reproduction before the zygote can be formed
  • Postzygotic barriers refer to the impeding of reproduction after the zygote has been formed
  • The main difference between Archea and bacteria is the presence of a peptidoglycan cell wall
  • Population density is related to a specified amount of space or area. Refers to the closness of individuals to one another.
  • Abundance : Some measure of the amount of a species in a sample.
  • A species is considered abundant when it has a high population relative to the size of the area it inhabits.
  • What are the characteristics of a living organism: Regulation, Response to the environment, Reproduction, Growth, Energy processing, Order, Adaptations
  • Asexual organisms: Have offspring that are exact genetic copies of themselves. There is no fusion of gametes.
  • Sexual reproducing Organisms : Two parents give rise to offspring that have unique combinations of genes inherited from two parents. The offspring varies genetically from each other.
  • Characteristics of Eukaryotic sexual life cycles: Meiosis Formation of diploid life stages through fertilization, Switch between haploid and diploid life stages.
  • Alternation of generations: Happens in plants (mainly), where the life cycle is divided into two phases: the generation of gametophytes (haploid stage) and the generation of sporophytes (diploid stage)
  • A haploid cell is a cell that has one set of chromosomes.
  • Diploid cells contain two sets of chromosomes
  • Organisms have the capacity to overeproduce, this works along side natural selection.
  • Artificial selection: The process by which humans select for desired characteristics in animals and plants.
  • If an environment changes or if individuals move to a new environment, natural selection may result in adaptation to these new conditions over time, sometimes this gives rise to speciation.
  • Individuals do NOT evolve, population evolves over time
  • Coevolution: the interaction between two species that results in the evolution of new traits that favours both of them