Evolution Test Flashcards
What was Lamark’s theory?
If individuals used an organ or a body part it would become larger and stronger. If its not used it would shrivel and weaken. (Ex.muscles) he thought these physical changes or “acquired characteristics” could be passed to offspring and change a species
What was Darwin’s theory?
Using his observations of finches and tortoises in the Galápagos Islands he believed that organisms evolve over time. He believed in natural selection, that nature could “select” traits that would pass on to following generations, while other traits were lost.
Ex. Finches on Galápagos Islands have different shaped and sized beaks for what food they eat. He believed nature had selected their beaks to meet the needs of their habitat
Giraffe example
Giraffes have a variety of neck sizes. Due to overproduction there’s a struggle for survival. When there are food shortages long neck giraffes would be able to eat from trees and expand their food supple while short neck giraffes starve. Therefore, the long necks would become the larger population and create more offspring. Long necks become more prominent while short neck giraffes don’t disappear
Population
Any group of organisms capable of interbreeding and coexisting in the same place at the same time
Gene pool
the sum total of all the alleles in all the individuals of a population
Acquired trait
Arises during an organisms lifetime as a result of the organisms experience or behaviour. Cant be passed to offspring
Natural selection
Organisms best suited to their environment were able to survive and reproduce more successfully than other organisms
Unity of pattern
Organisms may share the same structures, functions, and reproductive and developmental processes
Species
A group of actually or potentially interbreeding populations that are reproductively isolated from other groups
Founder effect
Describes the genetic effect of chance of assortment of alleles carried by the few founders who leave a larger population
Vestigial vs homologous traits
Vestigial trait are features that were useful to an ancestor but not useful to the modern day organisms that has them. (Ex. Human appendix) Homologous traits are similar features that originated in a shared ancestor. Homologous traits in different species indicate that the species shared a fairly recent common ancestor
Bottleneck effect
When in a short period of time the size of a population becomes unusually small, resulting in a random change in gene frequencies
Gradualism vs punctuated equilibrium
Gradualism is when some groups show gradual change throughout time, and adapt to traits favoured by natural selection. Punctuated equilibrium is when there are long periods of no evolutionary change caused by sudden changes such as natural disasters, disease, food supply change, etc
Examples of natural selection
Throughout time, black peppered moths became more prominent than white moths in areas with dark trees. This was because the dark moths could blend into the dark trees and hide from birds trying to eat them. White moths couldn’t hid and were eaten more.
Finches in Galápagos Islands differ in beak sizes and shape’s because of the food they eat. Finches who eat seeds have large, vice like beaks, and birds who eat insects have thin, needle nose plier like beaks
Divergent vs convergent evolution
Divergent- two or more related populations or species become so different that they can no longer interbreed. Its nearly always a response to different habitats, resulting in new species.
Convergent- different groups of animals have developed the same adaptations from living in the same environment, yet they are not closely related
