D.2d: Species and Speciation: Macroevolution

05/09/2013 § Leave a comment

It’s 4 in the morning and I’m doing bio homework, what’s new? (It’s okay, dudes, I slept for like six hours before this.) LET ME TELL YOU WHAT’S NEW. Divergent evolution and adaptive radiation, that’s what’s new! I think Mr. Ferguson would call all this macroevolution (hence the title of the blog) because the little speciations and evolutionary achievements work together to make big evolutionary changes.

Divergent evolution is when species evolve in different ways, normally by adapting to different ecological conditions so that they avoid competition with each other. When species diversify this way, it is called adaptive radiation (which is kind of vague to me because that’s, like, two words to fit into one definition?). An example of adaptive radiation, you ask? NO PROBLEM, MAN. You know marsupials? Yeah, well, the ancestral marsupials are responsible for the speciation of today’s koalas, wombats, and kangaroos. COOL? Yes, cool.

When natural selection acts the same way in different parts of the world (presumably because of similar environmental conditions), species can become very similar even if they are not related to each other – this is called convergent evolution (kind of like the opposite to adaptive radiation). Basically, unrelated species showing striking similarities = convergent evolution; related species showing striking differences = divergent evolution. GOT IT???

Finally, there is one idea on the rate of evolution called gradualism where evolution moves slowly but the little changes make large changes over time. Sound familiar? Yeah, sounds pretty friggin’ familiar to me, and it’s called macroevolution, you dingbats. However, there’s another idea called punctuated equilibrium which goes: periods of stability followed by short periods of rapid change, which suggest that a species is well-adapted during the periods of stability and natural selection chooses for them to maintain their characteristics, and in the periods of rapid change, drastic environmental changes (e.g. volcanic eruptions) are what cause natural selection to choose new characteristics.

…and that’s all for now, folks. Ohmygod there’s a test soon, ohmygod ohmogdyigdo ogdhkmdf.


Adaptive radiation of beetles, page 314

1. Using the pie chart, determine the fraction of all described species that are insects.


2. What could J.B.S. Haldane have meant when he said that God had “an inordinate fondness for beetles”?

Well, I mean, God doesn’t particular favour any one species (he loves everyone equally okay) but beetles hold the highest percentage of insects in the pie chart, suggesting that they are the most numerous and diverse type of organism.

3. Suggest why a switch to feeding on angiosperms could lead to such rapid speciation and diversification.

Perhaps switching to feeding on angiosperms introduced a whole new world of nutrients to the beetles and suited them better in their environment, making them stronger and more adapted to their habitat compared to other organisms. This would also differentiate them from other insects because the beetles switched to a new diet.

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