Blog # 4 Describe the three types of selection: directional, stabilizing and disruptive and give an example of each in your own words

directional selection
when individuals at one end of the curve have higher fitness than individuals in the middle or at the other end,directional selection takes place.such as,if there is a snack with normal venom,another snack has overwhelming venom.but the habitat they live are full with some strong prey who need to be kill by the powerful venom.then,the snack with overwhelming venom will be survive.as the result,the average venom intensity will be increase.

stabilizing selection
when individuals near the center of the curve havee higher fitness than individuals at either end of the curve,stabilizing selection takes place.for example,if there are two extremely lizards,one isyellow,and the other is purple.however,the nomarl lizards should be green.the yellow lizard's struggle is its color will make it die easier in its environment,and the purple one' color causes it can not hide itself perfectly.therefore,the amout of yellow and purple will decrese while the green one will have more offfspring.

disruptive selection
when individuals at the upper and the lower ends of the cureve have higher fitness than individuals near the middle,disruptive selection takes place.here it is,if there are three kind of horse,the first is small,the second is normal,and the third one is big.when they face a lion at the same time,the small one can run away very fast,the big one can threat the lion and make it afraid to attack,while the normal can do nothing.because of that,the population of the small and big one will raise,but the normal size will be decline.

Blog #3 Explain what microevolution is? What are the three ways that variation occurs?

microevolution is a change in gene frequency within a population. This change is due to four different processes: mutation, selection (natural and artificial), gene flow and genetic drift.Population genetics is the branch of biology that provides the mathematical structure for the study of the process of microevolution. Ecological genetics concerns itself with observing microevolution in the wild. Typically, observable instances of evolution are examples of microevolution; for example, bacterial strains that have antibiotic resistance.

These are the three ways that variation can occur.
1.mutation
A mutation is any change in a sequence of DNA.Mutations can occur because of mistakes in the replication of DNA or as a result of radition or chemicals in the environment,
2.gene shuffling
it occurs during the production of gametes
3.crossing-over
occurs during meiosis.Further increases the number of different genotypes that can appera in offspring.

Blog # 2 Why is fossil record hard to interpret?

First of all,fossil is a very ancient substance.lt occurs long time ago,can you regonzine a thing after millons of years?As a result,it is very hard to interpret fossil record because it's very old.Also,after evolution,many animals and plants alter their shape and apperance a lot.lt is more hard to distinguish them.People can just infer or guess which thing does this fossil record represent.The result may be unclear.Fossil is a staff with mysterious.lt kind of werid,too.The experiment on them will depend a lot of environment,history,and biology' knowledge.All in all,the fossil record is really hard for people to interpret or demonstrate.

Blog #1

Why is evolution a theory and not a law?
l think the most important reason for evolution is a theory because it can not be prove vividly or precisely by our telenogy now.lt  may be wrong or not totally correct,so it suppose not be a law.lt is just a good and beliveable demonstration.lt will be replace by more advanced and nicely theory in the future.Also,the earth occurs in this universe for a long time.lt's very hard to observe it clearly.Evolution theory can't be one hundred percent right.ln short,it's not a law because it depends some scientists' guess,and don't have enough essential details to show it is true without any doubt.