5.1 Flashcards
What is evolution?
Evolution is the cumulative change in heritable characteristics of a population
What are the three main sources of evidence for evolution?
Fossils, selective breeding, and homologous structures
How do fossils show evidence of evolution?
Fossils are usually found in the different layers of Earth in the order in which they would be expected to evolve. Using fossil evidence, scientists are able to link existing forms of organisms with their probable ancestors.
How does selective breeding show evidence of evolution?
Selective breeding is the process of repeatedly choosing the traits that most benefit humans and breeding animals with those traits. Scientists have concluded that if we can breed for selected traits artificially, nature can probably do the same naturally.
What are homologous structures?
Homologous structures are similar structures that exist in different species and have different functions in each of those species. An example is pentadactyl limbs, or limbs with five digits, which appear in lizards, whales, and birds, although these animals are not related.
How do homologous structures show evidence for evolution?
Homologous structures suggest that many organisms have a common ancestor from which they evolved and to which they had similar genes.
What is speciation?
Speciation is the evolution of a new species when an existing species is divided, leading to reproductive isolation.
What are the long-term effects of speciation?
Each separate population that is created through speciation is acted upon by natural selection and experiences changes in allele frequency. Eventually, the two distinct species will be so genetically different that they will no longer be able to interbreed.
What are gene pool barriers? List the types of gene pool barriers that exist.
A gene pool barrier is a factor that prevents certain species from mating.
3 examples:
-Geographic isolation: physical barriers separate possible mates
-Hybrid infertility: mates fail to produce functional gametes or fail to reach sexual maturity
-Temporal isolation: possible mates breed at different times
-Behavioral isolation: Mating rituals differ
What is gradualism?
Gradualism is the slow change from one form to another. Stable conditions lead to low levels of natural selection and make evolution a long, gradual process.
What is punctuated equilibrium?
Punctuated Equilibrium implies long periods without much change and short periods of sudden change. Mass extinction promotes rapid change and the formation of new species. Ex. volcanic eruption; meteor impact causing sudden climatic changes
Describe divergent evolution.
Divergent evolution occurs when species have very different characteristics but share a common ancestor. Ex. Homologous structure.
Describe convergent evolution.
Convergent evolution occurs when species share similar characteristics, but have different ancestors. Ex. Analogous structures ( the superficial resemblance of structures, i.e.: bat wing and butterfly wing)
What is industrial melanism?
Industrial melanism is the prevalence of darker-colored varieties of animals in industrial areas where they are better camouflaged than lighter varieties.
Give an example of industrial melanism.
In unpolluted areas, trees are covered in lichens and peppered moths blend in easily. Sulphur dioxide pollution from factories kills lichens and trees are blackened by soot. Melanic moths are well-camouflaged and have advantage over the peppered variety. In a short time, melanic moths replace the peppered moths, but only in polluted areas.
