Evolution Flashcards
Darwin’s first inference for the theory of evolution is “there must be a struggle for existence”. Why is this, and why is it important?
There are more individuals produced than the available resources can support, usually only few offspring survive in each generation and populations remain relatively the same constantly.
What are the lines of evidence used to support the theory of evolution by natural selection? Give examples.
Fossils (body fossils and trace fossils)
Anatomical record
Genetic sequences
Selection experiments (laboratory and field)
Define relative fitness.
The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.
Define relative fitness.
The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.
What are the key steps to speciation?
The characteristics of initially identical populations must diverge.
Reproductive isolation must evolve to maintain differences.
Define and give an example of allopatry.
Populations of related organisms are unable to interbreed because of geographic separation. Often leads to speciation where the two groups can no longer interbreed if they have been separated for long enough.
Examples; Galapagos finches on separate islands. 4 different species of Laupala crickets in the Hawaiian Islands. If an canyon opened up and separated a single population into 2 distinct populations
Define and give an example of homologous trait.
A trait that is similar between taxa because the organisms share a recent common ancestor.
Examples: bats, cats and humans have similar bone structure in their forelimbs.
Define and give an example of adaptive radiation.
Rapid set of speciation events following the discovery of new niches.
Examples: appearance of wings in bats allowed them to explore new niches that were previously unavailable to them. Galapagos finches went through rapid speciation once the first bird discovered the islands. Mass extinction events leave many niches empty and allow speciation of remaining organisms.
Define and give an example of hypothesis.
An intelligent guess as to how something works based on available knowledge.
Examples: the Pressure-Flow Hypothesis for movement of sap through phloem. The RNA-first hypothesis. Big Bang hypothesis.
Define and give an example of endosymbiosis.
A symbiotic relationship where one organism lives inside the other. Endosymbiotic theory explains the origins of mitochondria and plastids.
Examples: Escherichia coli bacteria living in mammalian digestive tract. Many corals have photosynthetic zooxanthellae inside their tissues. The bacterial present in cow stomachs that allow them to digest cellulose in grass.
