Biology 3602A/B Lecture Notes - Lecture 3: Homeostasis, Carboniferous, Osmotic Concentration

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5 Aug 2016
Cannot change chemistry and physics especially the laws of thermodynamics
Evolutionary history: an animal can only do with what it’s got
Selective pressures: what factors affect an organism
How do animals use energy
When we look at the life of an animal, animals do not obey the 2nd law; they become
more ordered and more complex as they grow to a certain point
Why not? We are an open system
How? transforming energy in order to fight the 2nd law
Temp of water is about 19oC, and core of the fish is 31oC with internal 300 mOsM (thus
hypoosmotic: lower solute conc than outside) while sea water is 1050 mOsM
So animal is significantly diff from its environment, and 2nd law of thermodynamics
doesn’t like this so animal has to use energy (that’s how) from environment and use its
systems to maintain the difference between the external and internal environment (i.e.
homeostasis), even if the water changes
Descent implies that there is heritable genetic material, which gives you traits and
interacts with the environment to produce a phenotype
Modification: animals that aren’t good enough are selected out
Looking at the descent portion of evolution:
The best data we have is that all life originated from one single common ancestor (this
means this is monophyletic)
Where we see animals branch off from other kingdoms, there is one common ancestor
So animals all evolved from one single species of organism
If we look at the evolution of life on Earth, Earth originated 4.5 bya, and life evolved not
too long after that (less than a billion years after), and then there was lots of evolution of
life until the first animal showed up (600-700 mya)
First animals evolved from the ocean (marine waters)
Those animals migrated up into fresh water, and some of them migrated onto land
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