The Big Issues- Trends in Evolution
Today the topic is "Trends in Evolution." What are the parameters for a trend? Are there trends in evolution? Are there evolutionary trends across lineages? Is evolution progressive? Let's dive in! 
Now that we have covered what a trend is, how is it applicable to evolution? Trends are not seen in evolution across all linages, for example size of organisms. It seems that a lot of species have grown bigger, but this is not the case across all linages, some sizes have decreased, so we cannot say there is one evolutionary trend across all linages. However, there are specific linages that show evolutionary trends. For example, the titanotheres (where horses and rhinos come from) show a trend in overall, not random, growth of their horn sizes.
A trend cannot be a random occasion, for example if it is 110 degrees out for one day when it is usually 70 degrees that time of year; if the heat continues for a period of years continuing in an upward direction, this could be considered a global warming trend. Trends for to be a trend in one direction or another.
Now that we have covered what a trend is, how is it applicable to evolution? Trends are not seen in evolution across all linages, for example size of organisms. It seems that a lot of species have grown bigger, but this is not the case across all linages, some sizes have decreased, so we cannot say there is one evolutionary trend across all linages. However, there are specific linages that show evolutionary trends. For example, the titanotheres (where horses and rhinos come from) show a trend in overall, not random, growth of their horn sizes.
Is evolution progressive? This is tough question to answer because this would mean something different from every linages perspective. For example, is it good that a snake's venom is delivered more effectively or does it make a difference that frogs live on land after their tadpole phase? Progress is defined in many ways.
Great job!
ReplyDeleteI love all the images you included in your blog post. They really help the reader follow along with your explanation, especially for me because I am a visual learner! Good job, keep it up!
ReplyDeleteI really enjoyed how you first explained what a trend was overall and with an example that does not evolve evolution. I think that this is very important as it can allow us to understand fully what it is first before trying to apply it to what we are learning in class.
ReplyDeleteI enjoyed your drawings and I also love that you mention progress being defined as many things
ReplyDelete