Processes of Evolution is a part of the VCE Biology area of study ‘How are Species Related?’ and subtopic ‘Changes in Biodiversity Over Time’. There are many processes which control and prevent evolution including:
- the action of mutations
- selection pressures
- isolating mechanisms
The Theory of Evolution by Natural Selection
We know that adaptations form over a very long time. They are specific features that complement an organism’s environment or increase their likelihood of survival. This is why organisms evolved to carry this adaptation.
The Theory of Evolution by Natural Selection explains this. Natural selection is a process in which individuals with more favorable traits have a higher likelihood of surviving to reproduce and pass on their traits to offspring. Over time, this affects the image of the population. The favorable traits become more and more widespread. The theory was published by Charles Darwin but discovered by both him and Alfred Wallace.
This video will go through The Theory of Evolution by Natural Selection in a little more depth and will look at Darwin’s finches.
This video is a short summary of the previous video.
If you have the time, watch this video to better understand how Charles Darwin and Alfred Wallace reached the conclusion of evolution by natural selection.
A Little at Australia’s Flora and Fauna
You will have to look at how some native Australian plant and animal species have adapted to the Australian climate over the years. Australia is a very dry, arid place. This has resulted in many plants adapting to preserve water, (e.g. eucalyptus leaves hanging down to reduce the amount of sunlight that gets on the leaf to reduce transpiration) and animals as well (e.g. the spinifex hopping mouse, highly concentrated urine to reduce the amount of water lost, large, thin ears and tail for heat loss).
This video goes through a few changes in Australian species
This is a good summary video for this post.
Cane Toads Demonstrate Selection Pressures in Action
The cane toad was an introduced species for agricultural purposes and despite starting with only 102 in the 1900s and releasing around 2400, the population has now grown to be well over 200 million. What is the cause of this growth?
The cane toad are a native species to South America where over millions and millions of years, their species have evolved in conjunction with all of the other species around it resulting in a complex network of predation and prey. In Australia, where there are no natural predators for the cane toad, they have gone unchecked. This has now lead to increased competition for native species who need to compete with this very hardy, highly toxic amphibian. The cane toad is highly adept for this environment as a result.
This is an invasive species, an introduced species that thrive due to a lack of negative selection pressures.
This video will go through cane toads in a little more depth.
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