Download Cottontail Rabbit Darwinian Explanation

Test Review for the Evolution Test
Read the following Darwinian Explanations and label each of the parts.
A: Population Past and Variation
B: Selective Advantage
C: Survival and Reproduction
D: Genes
E: Population Now and Variation
Cottontail Rabbit Darwinian Explanation
In the past cottontail rabbits had long ears although there were some that were shorter and
some longer than the average. The climate got colder and many of the rabbits with
longer ears died because their ears became frostbit (froze) and they lost lots of heat.
Most of those with shorter ears didn’t get their ears frozen and survived and were more
likely to reproduce. Since ear length is inherited (passed on by genes), the kids of those
rabbits with shorter ears tended to have short ears. Over many generations the population
of rabbits had an average shorter ear length. There were still some longer ears and some
shorter ears, but their average was shorter than in the original population.
Fur in Wolves Darwinian Explanation
In the last Ice Age, wolves had thicker fur than they do today. The original
population has thick fur, but there were some with shorter fur and some with longer fur.
When the Ice Age ended the climate got warmer. Those wolves with less hair survived
better because they didn’t overheat in the summer. They still stayed warm enough in the
winter since they winters were warmer than before. They were then more likely to
reproduce. The amount of hair in wolves is inherited so the babies of those wolves with
less hair usually had less hair. Over time the average amount of hair in the population
was less although there were some wolves with thicker and thinner hair than others.
Deep Sea Fishes Darwinian Explanation
In the past there were deep sea fishes living far down on the ocean floor that did
not glow in the dark. At some time mutation(s) (a change in the gene) arose that allowed
parts of some fish in the popuation to glow in the dark. Some of them even glowed at the
end of a projection of the head. Small creatures were attracted to the light because they
thought it was food. The fish with the light at the end of the projection on their head
“lured” small fish the best. They were able to eat the small fish and survive more often
since they could get food. They then were alive and were more likely to reproduce. The
ones with no light or light without a projection tended to not get enough food to survive.
Lights and projections are inherited, so those fish with them tended to have babies with
lights and projections. Over time the number of fish in the population with lights and
projections increased although there were a few fish without lights or projections.
Eyes in Owls Darwinian Explanation
At one time in the past, owls had smaller eyes than they do now. Some were
larger than others, however. Owls eat rodents and many rodents were becoming active at
night since they could stay away from predators that way. Those owls that had larger
eyes could see better in the dark and could see the rodents. They were better able to
catch the rodents and eat them and usually survived. The owls were then alive and were
more likely to reproduce. Those that didn’t get enough rodents for food usually died.
The owls with bigger eyes had more kids with bigger eyes since this trait is passed on by
genes. After many generations the average eye size in the population became bigger
although there are still some owls with smaller and bigger eyes than the average.
You can practice writing a Darwinian Explanation about how duck got webbed feet.
They started out without webbed feet.