Evolution and Classification Test
Usually the numbers of offspring produced are far greater than the ones that survive Natural resources are limited. This leads to a struggle for existence with only a fraction of offspring surviving to the next generation Slight variations (mutations) occur by chance within a population These variations are inheritable
Darwin concluded that living organisms were evolving through gradual changes over time Lamarck speculated that more complex forms of organisms arose from simpler forms based on acquired characteristics Lamarck believed that new species were produced by an internal drive toward greater complexity modified and the change was directed to meet the needs of the organism Darwin believed that new species were produced through natural selection and that variation exists regardless of an organisms’ needs.
Natural Selection: a mechanism by which individuals that have inherited beneficial adaptations produce more offspring on average than do other individuals. In nature, the environment is the selective agent.
In nature, characteristics are selected only if they give advantages to individuals in the environment as it is now. Natural selection is based upon 4 principles:
Descent with modification
Artificial Selection: the process by which humans change a species of breeding it for certain traits. Humans make use of the genetic variation in plants/animals by acting as the selective agents.
Homologous structures: Features that are similar in structure but appear in different organisms and have different functions. Share a common ancestor
Example: forelimbs of humans, bats, and moles
Analogous structures: Features that serve related functions, but do not show common ancestry. Example: wings of bats and insects
Adaptive Radiation: Divergent and Convergent evolution
Divergent Evolution: Species diverge and move away from a common
ancestor into new novel habitats or niches. Ex: homologous structures
Convergent Evolution: species develop similarities based on their similar
environment and similar selection pressures. Ex: analogous structures
Vestigial organs: remnants of organs/structures that had a function in an early ancestor but are no longer essential Example: human appendix
Species: a group of organisms so similar to one another that they can reproduce and have fertile offspring.
Speciation: evolution of 2+ species from 1 ancestral species 1. Founding members
2. Separation of population
3. Changes in gene pool
4. Reproductive isolation
5. Coexistence, extinction or further evolution
Reproductive isolation: final stage in speciation, in which members of isolated populations are either no longer able to mate or no longer able to produce viable offspring. New species form when 1 population becomes isolated from another and do not interbreed Due to geographic barriers, courtship, behaviors, or differences in breeding times No gene flow
Without exchange of genetic info changes in their genes can eventually form separate species. The founding members of the new population can no longer interbreed with the original population in the wild.
Geographic isolation: involves physical barriers that divide a population into two or more groups. This is the most commonly studied type of isolation.
Classification: method used to order or group organisms
Similar nomenclature throughout the world
Compare relationships and evolutionary histories
Based on shared characteristics
Taxonomy: science of classifying and naming organisms
Groups organisms into hierarchical categories
Starting with the largest grouping, the organisms were placed into smaller and smaller groups (that share more and more...
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