Evolution chapter 2 Flashcards

Evolution can be defined as a change in the frequency of a trait in the gene pool.The gene pool is all of the genes in a certain population. Organisms must reproduce to pass on genes, so they must live long enough to reproduce in order to affect the gene pool

The ancient preserved remains of an organisms are fossils and they can show evidence of evolution. Paleontology - the study of fossils plays a central position in the study of evolution. It helps display ancient organisms and sequences of change they took to become their modern day equivalent. Fossils can be dated using radiometric dating. It measures how much cabron 14 is left in an organisms and how much has decayed into nitrogen 14. For ex: if the fossil is half c-14 and half n-14 that is the half life for c-14 and it is 5700 yrs old. In general over time organisms have become more complex

The variation and distribution of life over the earths surface in today and in the past shows where organisms have come from and how they evolved in response to seperation. Through studying fossils on different continents we have seen that evolution has occured after the continents seperated from pangea. Studying islands far removed from land masses has shown they have many unique species, some are endemic (found nowhere else), which shows they have evolved in isolation

Embryology is the study of organisms in their early form of devlopment. Scientists beleive that the evolutionary history of an organism can be seen to unfold during its development. For Ex: a human fetus posesses gill pouches as one point in the embryo, then later exihibit a tail (turns into tailbone) and also fur which are all lost after development. Through these observations we beleive that new instructions are laid over old ones to "override them."

They are structures that are similar but have different functions, they are an example of divergent evolution (same structure branches out to be used for diff functons) they imply evolutionary relationship. Adaptive radiation is when organisms have similarities in homologous structures due to common ancestry. Ex: many animals have pentadactyl limbs but use them for diff. functions like bats for flying, whales for swimming, etc. Enviromental selection pressures can cause these modification to take place. (good traits allow organisms to live = they are passed on, bad = they die = traits not passed on).

They are structures that are similar in appearance and in function but do not appear to have the same evolutionary origin Ex: a bird and an insect evolving wings to survive better. They are an example of convergent evolution, two unrelated species evolve the same structure due to usefulness.

Vestigial organs/structures are reduced or functionless remnants of organs/structures that were more prominent in ancestors. Ex:dogs vestigial toe, pigs vestigial digits, Human Appendix, wisdom teeth, etc. Vestigial genes are genes that are old information or repeated information (large portion of our DNA). For ex: we carry the genes to make vitamin C but lack the ability to carry it out.

Differences in amino acid sequences in a portion of hemoglobin protein reflect the degree of similarity among species. There is a large number of molecular similarities between all organisms. Ex: organisms that are closely relaed share more DNA and therefore shared a common ancestor at one point.

Artificial selection is the process of humans selecting and breeding individuals with the desired traits. We can see evolution occuring at a much faster rate when controlled by humans. Ex: breeding the seeds away in bananas.