Review Answers
C-10 pages 304-9
Selection is the factor that determines which individuals of a population survive and which do not. In our bean-gathering activity, “selection” was the made by the points earned: more points = increase population. Selection “sorts out” which variations work best. These variations can then be said to be “adapted” to the environment. They “fit.” Their “fitness” is shown by having more offspring — more babies that fit the environment just like the parents.
C-10 310-17
fossils, biogeography, embryology, anatomy (homologous = similar body parts), vestigial organs, genetic similarity
C-11 328-9
(look at the diagram in the book) phenotypes are visible traits like the frog’s color; genotypes are the alleles – GG, Gg, gg – that create the traits; the G’s and g’s that compose the population are the gene pool; the percentage of G’s and g’s is the allele frequency.
If a dominate phenotype is eliminated, all of the G’s will be removed. The G % changes to 0. Then the g’s are 100% of the population. Selection only works on phenotypes. When the number of individuals with any particular trait changes in the population, the allele frequency will also change. This change IS the modern definition of evolution.
No, hybridization does not mean half of one species joined to half of another. It means two different mammal OR bird species could interbreed to make a new species, a hybrid mammal species OR bird species.
C-11 330-3
A normal distribution is a bell-shaped curve like Figure 11:2. Human height is like this: few are very short and few are very tall (the edges of the bell). Most people are “average,” somewhere in the middle.
The distribution can shift is new selective conditions occur. If “tallness” or “shortness” became deadly or for some reason were eliminated (stopped reproducing), then the average height would shift to one end of the graph or the other as is shown by Figure 11:5. Height makes no difference to human survival, so height has the “normal” distribution. Other creatures, like honey bees for example (or kinglets, or mockingbirds, etc.), are almost all exactly the same size. So there must be some factor that makes this exactness important in the bee world.
C-11 343
genetic drift, gene flow, mutation, sexual selection, natural selection
(A good activity for this is at Classzone here.)
C-11 344-6)
reproductive, behavioral, geographic, and temporal.
Any of these factors can split a single population into two or more separate populations. When this happens (such as a group of finches leaving the mainland and moving to the Galapagos), the different populations are stressed by different environments. Because they are no longer interbreeding populations, natural selection will work on their unique variations and slowly change the characteristics of each group. Their genetic make up will change. Eventually members of each population are so different that they will not interbreed; they are now new and separate species. This is “speciation.”
