Hey everybody! This is Matthew Hernandez. Welcome to my video on natural selection.
In this video, I will be defining the theory of evolution as well as natural selection, a mechanism of evolution.
More importantly, you will understand how natural selection produces evolution.
Let's start off by defining theory of evolution.
It refers to a change in allele frequency and there are some implications you should remember.
Evolution involves allele frequencies measured at the population level not individual. This change occurs at the genetic level.
Evolution occurs in traits.
Charles Darwin, known as the father of evolutionary thinking, devised the theory of natural selection to explain the process of evolution.
This theory suggests that beneficial
alleles increase in frequency over time in a population
as a result of increased survival and reproduction of those with the beneficial alleles.
You might have heard of survival of the fittest.
It refers to how the species that is most responsive to change will survive,
not the strongest or most intelligent.
Natural selection is based on some key observations:
variation, overproduction, selection, and adaptation.
The first key understanding is that traits are inherited via genes passed on from parent to offspring
In this process, comes variation this means offspring will have slightly different traits.
Overproduction occurs, which means too many offspring are produced leading to
limited resources and inevitably competition.
There are some better suited or advantageous traits the advantageous traits are passed on to the next generation
selection occurs as a result of competition from overproduction.
Finally,
adaptation refers to how a population will adapt to its environment and have more
reproductive success from one generation to the next.
The following is a good example of how natural selection produces evolution
A group of mice, some with black and others with tan fur, has moved into a new area with black rocks.
In this environment, the hawks like to eat mice the tan ones stick out many more of the tan
mice are eaten, since they are more easily seen
Only the surviving tan mice will reproduce while the black mice with better survival were produced more.
After several generations, the population will be majority black.
Let's remember some key points about natural selection
It depends on the environment.
It emphasizes traits and alleles and occurs in populations, not individuals.
It acts on existing heritable variation.
Here I included the key terms and definitions
related to this concept. Feel free to pause the video and review before continuing.
I have included page numbers so you can refer to the lab manual for further clarification
At this point, I have reviewed evolution as well as natural selection and have included examples.
Now it is your turn to practice with a POP QUIZ!
Which of the following is not a key component of natural selection?
A. Traits for strength and vitality are favored over other traits
B. Random variation exists for every trait in a population.
C. There will always be
competition for resources or D. Those with the advantageous traits will outreproduce others.
Feel free to pause. If you get stuck, it's in the lab manual in Chapter four.
Welcome back. Did you get it? Let's take a look...
The correct answer is A. You may remember the example from the book...
Bigger and stronger is not necessarily advantageous as with the dwarf mammoths from whom smaller was most advantageous,
since they needed fewer resources, and that's how the future generations evolved.
I hope you enjoyed learning about the theory of evolution
Charles Darwin, natural selection and reproductive success.
I included all my references at the very end
Thanks for watching.
Bye everybody!
