Evolution
Evolution is the change in allele frequency. In simpler terms, it is the trait that changes over time in a population. There are four ways in which evolution takes place, mutations, genetic drift, migration and natural selection.
Mutations are the change in base sequences. This is the only way new alleles are created. These alleles can either be helpful or harmful, and may or may not determine reproductive success. Mutations must be heritable so it can pass on to future generations. The next way that evolution occurs is through genetic drift.
Genetic drift is a random change in allele frequency, and has two components to it, which are founder effect and population bottleneck. The founder effect is when a random selection from a larger population is taken and moved to a new area. Population bottleneck is when a new population is dominated by genetic features present in the surviving members, which is most likely due to a natural disaster of some sort.
The third way evolution presents itself is through migration. Migration is when a group of individuals move from one population into another existing population.
The last example of evolution is natural selection, which is the survival of the fittest, or the best adapted to the environment. The three types of natural selection are stabilizing selection, directional selection, and disruptive selection. Stabilizing selection would be the environment supporting the medium. For example, in the diagram to the left, the mouse of a tan color, or an in between color is the highest in population. Directional selection is where either extreme is supported. As reference to the diagram, either the mouse with really dark fur, or very light fur will be supported. Lastly, disruptive, or diversifying selection is when the environment supports either extreme, so the mice with dark brown fur, and white fur dominate the population.
Scientists have proved evolution through; fossil records, geography and species, comparative anatomy, molecular biology, and field studies. The first piece of evidence, fossil records pertains to how old fossils are, showing which structures could be dated back to an almost exact year to which they existed.
The next indication is geography and species. The theory of Pangaea connects to this, as there are similar fossils found on South America, and Africa. With these similar environment, comes similar ancestors.
The third documentation is comparative anatomy, which has five sections to it. Comparative anatomy consists of homologous structures, vestigial organs, divergent evolution, convergent evolution, and embryology. Homologous structures is the comparison of bones. The similar bones in organisms indicate a common ancestor. Whales and humans have similar homologous structures, but a whale's flipper has masked its hand-like skeleton. These different appearances, yet similar skeletons show how different species adapted to different environments. Vestigial organs are structures that were once used but no longer serves a purpose. Whales have pelvises which are a structure that holds up legs. Divergent evolution applies to the adaptations of similar species to different environments. A popular example of this is Darwin's finches. Every beak is specific to each type of food that is provided in different environments. Convergent evolution is how unrelated species show similar characteristics due to similar environments. For example, orcas and penguins have pelagic coloring which allows for better camouflage in the sea. The last component to comparative anatomy is embryology. Most embryos looks very similar, whether it be humans, fish, or pigs.
The fourth piece of evidence to prove evolution is molecular biology, which is simply whoever is genetically similar, is related.
The last way that evolution is proven is through field studies. This method shows how environmental pressures are different.
Fossils of cephalopods have been found all over, these of which most likely came before the cuttlefish. The three most well known fossils are the Nautiloidea, the Ammonoidea, and the Coleoidea. These are all cephalopods that came before cuttlefish, yet share very similar characteristics. To read in depth about these different species, go to this link : [1]
"Cuttlefish, along with octopuses and squid, are cephalopods—animals from an ancient branch of the tree of life that have been trolling the oceans for more than 500 million years. Cuttlefish were around long before the first shark or fish ever evolved. Their cephalopod ancestors were encased in a shell that acted as protection from predators, but the modern cuttlefish has developed an even better defense: camouflage" [2]
SPECIAL ADAPTATIONS
Their color change does not only help them with camouflage, but can allow these creatures to communicate. [3]
When cuttlefish attack their prey, they use their longest tentacles to capture small fish.
They flash bright and vibrant colors to scare away predators
"The cells on the skin of a cuttlefish are covered in tiny dots of all colors, much like the tiny dots that make up the screen of your computer. A cuttlefish can make their cells grow or shrink to bring out the perfect blend of colors to match whatever is around it." [4]
The next indication is geography and species. The theory of Pangaea connects to this, as there are similar fossils found on South America, and Africa. With these similar environment, comes similar ancestors.
The third documentation is comparative anatomy, which has five sections to it. Comparative anatomy consists of homologous structures, vestigial organs, divergent evolution, convergent evolution, and embryology. Homologous structures is the comparison of bones. The similar bones in organisms indicate a common ancestor. Whales and humans have similar homologous structures, but a whale's flipper has masked its hand-like skeleton. These different appearances, yet similar skeletons show how different species adapted to different environments. Vestigial organs are structures that were once used but no longer serves a purpose. Whales have pelvises which are a structure that holds up legs. Divergent evolution applies to the adaptations of similar species to different environments. A popular example of this is Darwin's finches. Every beak is specific to each type of food that is provided in different environments. Convergent evolution is how unrelated species show similar characteristics due to similar environments. For example, orcas and penguins have pelagic coloring which allows for better camouflage in the sea. The last component to comparative anatomy is embryology. Most embryos looks very similar, whether it be humans, fish, or pigs.
The fourth piece of evidence to prove evolution is molecular biology, which is simply whoever is genetically similar, is related.
The last way that evolution is proven is through field studies. This method shows how environmental pressures are different.
Fossils of cephalopods have been found all over, these of which most likely came before the cuttlefish. The three most well known fossils are the Nautiloidea, the Ammonoidea, and the Coleoidea. These are all cephalopods that came before cuttlefish, yet share very similar characteristics. To read in depth about these different species, go to this link : [1]
"Cuttlefish, along with octopuses and squid, are cephalopods—animals from an ancient branch of the tree of life that have been trolling the oceans for more than 500 million years. Cuttlefish were around long before the first shark or fish ever evolved. Their cephalopod ancestors were encased in a shell that acted as protection from predators, but the modern cuttlefish has developed an even better defense: camouflage" [2]
SPECIAL ADAPTATIONS
Their color change does not only help them with camouflage, but can allow these creatures to communicate. [3]
When cuttlefish attack their prey, they use their longest tentacles to capture small fish.
They flash bright and vibrant colors to scare away predators
"The cells on the skin of a cuttlefish are covered in tiny dots of all colors, much like the tiny dots that make up the screen of your computer. A cuttlefish can make their cells grow or shrink to bring out the perfect blend of colors to match whatever is around it." [4]