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Misconceptions about Natural Selection Read this before you attempt this assignmentLinks to an external site.
Links to an external site.
WARNING!!!!!!! **DO NOT Use DOGS or PEACOCKS For your SCENARIO**Dogs are bred by humans so not a good choice for natural selection and Peacocks are a better choice for sexual selection than natural selection and you are not giving a sexual selection scenario.
Your assignment is to create a scenario that demonstrates the process of natural selection
A scenario is a step by step telling of how this came to be using the STEPS of the natural selection PROCESS. It can be (and should be!!!) fictitious (fake) but the application of the steps has to be correct.
the steps of natural selection
start with variation in a trait in a population which is the result of a random mutation that has occurred during the process of meiosis. ( ex. the species is a spider and the spider has tentacles that they breath through so they can bury themselves in sand and still breath. a little spider is born and its tentacle can also function in water but no one knows this yet because it hasn’t needed to work that way yet.
Then there is some change in the environment. – ex. SO if it was a dry desert but now it has rained for a century in that area and now it is a lake thats a change in the environment
There are members of the population now with a variety of that specific trait which will help them survive at a greater rate than the members of the population without that variation. ex. So now all the little spiders who have the weird tentacle that also can breath in water survive and the others have a harder time surviving.
CONCLUSION – Ex. Overtime the water breathing spiders survive and therefore reproduce at a greater rate than the other spiders and so the species seems to have evolved from sand breathers to water breathers.
If these steps are not apparent in your scenario YOU WILL NOT RECEIVE CREDIT. I am really serious about this.
Students who rush through this assignment do not do well and do not receive credit – a big part of your grade is showing that you have studied the steps in the natural selection process and are now applying them to your example.
Students who copy an example of natural selection from the internet do not do well on this assignmentREMEMBER your scenario only has to show a logical application of the steps of natural selection. DO NOT RESEARCH A PARTICULAR TRAIT OF A PARTICULAR SPECIES AND COPY WHAT YOU FIND – I guarantee you will not get credit for this type of response because you will not be writing about it in the way the assignment asks you to apply the steps.
Remember Natural Selection is a process. so your job is to show that you understand the steps in this process by applying the steps to a specific trait for a specific animal or plant do not talk about more than one trait. For example, don’t write about a lion’s claws and it’s size just choose one feature.
Natural Selection Crash CourseLinkLinks to an external site.
Useful format
Species = Spiders
Variation = non tentacled vs tentacled a variation that emerged from a random mutation prior to any change in the environment
Change in the environment = desert area is flooded and is now a lake
Effect on species gene pool = Spiders with tentacles survive at a greater rate and thus produce more offspring than the non-tentacled variety.
Outcome= over time it appears that the species has evolved from a non-tentacled species to a tentacled species.
Processes of Evolution
READ:
Explorations Forces of Evolution.pdfDownload Explorations Forces of Evolution.pdf
Explorations Ch8 Primate Evolution.pdfDownload Explorations Ch8 Primate Evolution.pdf
Evolution is both a theory and a fact.
The first part of this statement refers to continually expanding our understanding of the process of evolution. We know evolution, change over time, occurs in all living species, through processes of mutation, natural selection, genetic drift, and gene flow or migration. The second part of the statement, evolution is a fact, means that we know evolution occurred because we can observe it through the fossil record as well as in plants and animals, such as insects, which have much shorter lifespans than ours.
Our job in this class is to gain a clear understanding of mutation, gene flow, and natural selection and in this way, we can better understand the processes of evolution.
Mechanisms of change:
Each of these four processes is a basic mechanism of evolutionary change.
variationMutation
A mutation could cause parents with genes for bright green coloration to have offspring with a gene for brown coloration. That would make genes for brown coloration more frequent in the population than they were before the mutation. ***Notice the variation present here in the first generation there are two large green beetles and one smaller brown one. That’s the random mutation that has occurred during meiosis and created this variation. This odd beetle, doesn’t seem to fit in now but will turn out to be an advantage later
gene flowMigration
Some individuals from a population of brown beetles might have joined a population of green beetles. That would make genes for brown coloration more frequent in the green beetle population than they were before the brown beetles migrated into it.
genetic driftGenetic drift
Imagine that in one generation, two brown beetles happened to have four offspring survive to reproduce. Several green beetles were killed when someone stepped on them and had no offspring. The next generation would have a few more brown beetles than the previous generation — but just by chance. These chance changes from generation to generation are known as genetic drift.
best suited allude the predatorNatural selection
Imagine that green beetles are easier for birds to spot (and hence, eat)(Here’s where that variation from the random mutation comes in handy!). Brown beetles are a little more likely to survive to produce offspring. They pass their genes for brown coloration on to their offspring. So in the next generation, brown beetles are more common than in the previous generation.
All of these mechanisms can cause changes in the frequencies of genes in populations, and so all of them are mechanisms of evolutionary change. However, natural selection and genetic drift cannot operate unless there is genetic variation — that is unless some individuals are genetically different from others. If the population of beetles was 100% green, selection and drift would not have any effect because their genetic make-up could not change.
natural selectionLinks to an external site.
Natural Selection continued
Remember it is our job in this class to move away from popularized notions of scientific processes and instead to understand how they actually work.
Many of us have a pat answer that natural selection is adapting to the environment, as if it can be willed, or happens magically when needed, but this is too simple and not accurate. The term adapt has to be more carefully defined.
When we say a species adapted it means that there was variation in that species and some of the members that had a feature that suited the conditions in the environment at a given time survived and had offspring while some other individuals didn’t. And for this reason, more offspring were born to the ones with the suited variation than were born to other variations. So over time, the population seems to have changed from one variation that was more suited at an earlier time to this other variation that is suited in these conditions.
This is a helpful link to get a better grasp of how natural selection works.
UNDERSTANDING EVOLUTIONLinks to an external site.
Variation is important to the success of all living things.
When we discuss evolution we talk about the mechanisms of change working in populations of a species. Remember to use this term when you write about speciation later.
A species population is a discrete group of potentially interbreeding organisms in the same species in a given locality.
In a species’ populations, there are many factors which interfere with an individual’s ability to survive and reproduce.
This ability to produce the most offspring that are viable and fertile is known as “Fitness”. So, It’s a different meaning than the way we use the term today in our culture.
Fitness = leaving more offspring in the next generation What Survival of the fittest really means (Links to an external site.)Links to an external site.
Another type of selection is sexual selection. This means that one sex of the species is adapting to the courtship behaviors and reproductive condition of the species.
Sexual selection is different than natural selection Sexual Selection
Really understanding what sexual selection is and how it is different from Natural SelectionLinks to an external site.
(Don’t confuse the two when you are completing your natural selection assignment.)
Here is a very helpful interactive video about Natural selection. View it completely and complete the interactive quiz.
New Mexico Pocket Mice Link Links to an external site.
Gene Flow
means that an individual from one population of a species goes to another population of the same species and has sex with a member of that other population. So now His or Her genes and alleles are part of the Gene Pool of the population he or she visited and had sex and left a fertile offspring there.
Gene Flow creates more variation in a population and this is a good thing for a species because it creates more options for kinds of members that will be able to survive and reproduce under new and challenging conditions.
Look at this video about the Evolution of Populations The Evolution of PopulationsLinks to an external site.
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