Evolution Flashcards
(38 cards)
Voyage of the Beagle
Charles Darwin (born Feb 12, 1809, in England) set sail in 1831 on the H.M.S Beagle. Made numerous observations, collected and studied specimens/fossils, and discovered patterns of diversity that led him to propose a revolutionary hypothesis about how life changes over time (the theory of evolution).
Ideas that shaped Darwin’s thinking
Lots of fossil records much older than what was then believed to be the Earth’s current age.
James Hutton
1795 geologist, thought that Earth was very old.
Charles Lyell
1831 geologist, thought the processes of shaping the now and the past were the same (erosion, weathering, volcanos).
Jean Baptiste Lamarck
Thought living things change over time and species are descended from other species. Lamarck’s theory of evolution dictated that the tendency toward perfection helped with survival (use & disuse) as well as the inheritance of acquired traits. He was wrong because behavior doesn’t affect DNA and he didn’t know how traits were inherited.
Thomas Malthus
Thought that unchecked population growth would quickly overpopulate the earth (more births than deaths). Darwin questioned what caused the deaths of so many, and what factors determine which survive and reproduce. Concluded that in nature, all species tended to produce more offspring than they could support.
Galapagos Islands
Islands are close together but have very different climates, Darwin was fascinated by the different species of land tortoises and marine iguanas across the islands.
Alfred Russell
Darwin worked with Alfred Russell in 1858. Wrote an essay summarizing Darwin’s theory of evolution.
Darwins book
Darwin worked on his book for years but was scared to publish it because of religious backlash, but he published “On the Origin of Species by Means of Natural Selection” in 1859.
Artificial Selection
Nature provides the variation and humans select the variations they find useful.
Natural selection
Nature (the environment) will determine the organism that is the fittest to survive, results in changes in the inherited characteristics of a population, and increase fitness over time.
Struggle for existence
The highest fitness species can survive and reproduce in its specific environment, which results from adaptations.
Descent with modification
Each living thing has descended with changes from species over time.
Convergent evolution
Similar species in similar environments, unrelated species come to resemble each other, e.g placentals and marsupials.
Divergent evolution
Two or more species becoming more and more dissimilar.
Analogous structures
Structures that serve the same function in different species but evolved independently, e.g bat and butterfly wings.
Vestigial organs
Organs that serve no useful function in an organism, because their presence doesn’t affect fitness.
Homologous body structures
Structures that have different mature forms in different organisms but evolved from the same embryonic tissues.
Mutagens
E.g UV rays and harmful chemicals, causes DNA to mutate.
Mutations
Usually not advantageous but can be, can cause the organism to die. DNA mutations control evolution, positive mutations are selected by the environment and eventually accumulate throughout generations.
How do variations occur
When an individual can contribute its alleles to the population’s gene pool, it may increase the frequency of the alleles. Evolution is any change over time in the relative frequencies of the population.
Single gene traits
Natural selection of non-single gene traits can lead to changes in allele frequencies and thus to evolution.
Directional selection
Occurs when individuals at one end of the curve have higher fitness than individuals in the middle or other end.
Stabilizing selection
When individuals near the center of the curve have higher fitness than individuals at either end of the curve (human babies).
