Mechanisms of Evolution Flashcards
Gradualism
Hutton
Natural selection and biogeography
Wallace
Basic Genetics
Mendel
Iron law of population
Malthus
The modern synthesis
Fisher, Haldane , wright and others
Earths geology and geography changes suddenly and violently over short time spans
Catastrophism
A complexifying force pushes organisms to be more complex throughout their lives, meaning the most complex organisms are the oldest life on Earth
Lamarckism
Earth’s geology and geography have changed ( and continue to change) both gradually and in violent events over long spans of time
Uniformitarianism
Populations grow geometrically, but resources on l only increase in a linear manner, leading to a struggle for survival
Iron law of population
Malthusian competition, genetic variation and mutation, natural selection and mendelian inheritance all contribute to and drive evolutionary change
The modern synthesis
Which of the following is a commonly held misconception about evolution ?
Evolution is
purposeful and directed toward and optimum goal of increasing complexity and efficiency in all species
Sexual selection and non-random mating
Ring Finger
Genetic drift and small population size
Pinky Finger
Natural selection
Thumb
Gene flow and migration
Index Finger
Mutation and Genetic variation
Middle Finger
Observing the musculature and bone arrangement of a human hand and a chimpanzee hand reveals exceptional similarities in both structure and function. These two hands are likely derived from a common ancestor.
Homologous structure
Samples of DNA sequences coding for ribosome production are incredibly similar among all Eukaryotes. This provides evidence that all Eukaryotes likely came from a single ancestor who had had ribosomes similar to ours.
Molecular Biology
Observing the skeletal remains of modern snakes reveals small boney growths where a pelvis would have existed and legs would have attached. These boney remnants give clues that the ancient ancestors of snakes would have been reptiles that had legs.
Vestigial structures
Since the Eocene, remains of small horse-like organisms have appeared in the fossil record. Once collected, these samples provide for a clear evolutionary timeline showing how primitive horse ancestors into modern day horses.
The fossil record
Observing the current species distribution and fossil remains of mammals in South America and Africa shows incredible similarities in the types of mammals on these two continents. Mammals that evolved prior to the break-up of Pangaea area found on both continents, whereas mammals that evolved after the break-up are only found on one continent or the other
Biogeography
A sudden change in climate causes the island to become very cold. It begins to snow all the time. The Hornless Heffalumps are better able to burrow and hide in the snow. This protects them from predators. The Horned Heffalump’s bright purple horns make them easy to spot in the snow, and they are killed by predators at a higher rate.
Natural Selection
The Horn on a Heffalump is always purple. One day, a baby Heffalump is born with green horns. His descendants also have green horns. This trait becomes common after 10 generations.
Mutation
A population of only 30 Heffalumps is very small. Once day, a tremendous tsunami engulfs the island, killing 26 of the Heffalumps. The 4 remaining Heffalumps happen, by sheer chance, to be Hornless. From that point on , having horns is incredibly rare.
Genetic Drift
Hornless Heffalumps do not see as picky, and will mate with whomever is available. Although it doesn’t seem ethical, studies show that Horns Heffalumps will only mate with other Horned Heffalumps. This prefeerancees leads to changes in the gene pool and eventually Horned and Horneless become unable to mate due to reproductive isolation
Sexual Selection
About 10 Horned Heffalumps decide to build a raft and seal to the mainland, leaving the rest of their population behind.
Gene flow
