Basics of evolution and allels
The changes in allele's are very important parts of evolution. The changes of alleles are called allele frequency. There are four different types of allele frequencies. The first one is mutation. In mutation, there is a change in the DNA sequence that caused the mutation. This mutation could be harmful, meaning that the animal dies from it, or it could be helpful if the animal is able to reproduce and the new allele has to be heritable, but this new mutation could also affect their reproduction success, meaning it could cause reproduction to be harder for them. Another allele frequency is genetic drift, which is a random change in allele frequency. This could be represented by the pop. bottleneck, which is when a natural disaster strikes and only some individuals survive, making them have to reproduce with each other, and they would keep reproducing with each other, just to survive. Genetic drift could also be represented by founder effect, when a group separates themselves and move to a new area. Another allele frequency is migration, sometimes referred to as gene flow. In migration, a group of individuals moves form one population to another. This could add new allele to the alleles that were already in the area. The last allele frequency has to be the most known, called natural selection. In natural selection, the most famous quote is "survival of the fittest," which means those best suited to the environment, survive, and reproduce. This theory is well known from Charles Darwin in the 1830s. Natural selection works from the animal's adaptation, the environment, and the animals' variation. There are three different types of natural selection. The first type of natural selection is stabilizing selection, which is when the environment favors the average. The could be the shortest/ slowest and tallest/fastest losing to the medium winning. Another natural selection is directional selection, which is when the environment favors one extreme. In this selection, the shortest/ slowest could be favored over the tallest/ fastest, and vice versa, but the environment does not favor the medium at all and they are on the losing end this time. The next natural selection is disruptive selection, which is when the environment favors, both shortest/ slowest and the tallest/ fastest at the same time, and even her the medium is still on the losing end of things. Natural selection could be seen in many things creatures in the animal kingdom. All of this could even be seen in humans, form when we first started as monkeys and evolved into very sophisticated creatures, at least this applies to some of us. Read on and see how this also applies to Pearl Clams.
Evidence of Different type of EVOLUTIONS
- Fossil- You could think of fossils has the old bones of every living things' ancestor, because that's what they are. The shapes of those bones show how much a spices have evolved from the time the bone have been buried.
- Comparative Anatomy:
- Homologous structures- When an animal have the same bones structures, such as whales, humans, cats, etc., it shows that they share the same ancestor.
- Convergent Evolution- When animals that don't share the same ancestry but because they share the same environment, they evolve to have similar structures, such as sharks and dolphins.
- Vestigial Structures- This is when body parts from ancestors are still there in the descendants, for example whale pelvis, human tailbones, and their appendix
- Embryology- The embryos in fish, pigs, and humans are similar, showing that they all have common ancestry. The biochemistry is also the similar, their amino acids are the same because they have the common ancestry.
Evolution of pearl clams
Special Adaptations
- Pinctada maximas makes pearls inside of them
- A foot that helps them move around, this is something other Bivalves can't do
- They eject sperm and eggs into the water at the same time, making them sexually creatures
- Adductor muscles to keep predators out
Where have we seen EVOLUTION
![Picture](/uploads/2/6/4/7/26477440/140845762.jpg?583)
Humans have evolved quite a bit. What secentist could tell from fossils is that humans originated from apes (monkeys) and overtime, not an individual, they began to walk straighter and grow taller. They are theories that all the hair started disappearing more because of evolution and this is true because humans started wearing clothes to cover themselves up so having all that hair was not necessary and so it went away. This is a good example of somethings staying and some disappearing with evolution. Only the individuals that live to survive gets to pass down traits of less hair all over the body.
As shown in the picture, there is solid scientific evidence that there was earlier forms of Bivalves. Bivalves ancestors is one of the creatures the were here when the world started have very complex and were multi-cellular organisms. They have fossils to prove the evolution of the clams from univalves to bivalves. A reason for the evolution is because when the clams get moved to different environments, the most adapt to it or they'll die. A univalve can't be opened to get the food they needed in the water, so the clams that were still univalves would die while those with two shells would live and pass down those traits to their offsprings.