Parsimony, molecular clocks, and reproductive isolation in evolutionary biology

Biology

Species

Species D

In evolutionary biology, parsimony is similar to the Ockham's razor hypothesis, or that nature will use the simplest method possible to effect change over time.

Phylogenetic systematics is the manner in which biologists reconstruct the pattern of events that have led to evolution and the distribution of unique species. The statement "DNA is the genetic material for all prokaryotes and eukaryotes" implies that DNA is the locus material for evolutionary change.

Assumptions include that there is a strong possibility that some evolutionary changes occur in a regular, clock-like manner. For instance, over millions of years, mutations build up in DNA at a reliable rate, and then are expressed in regular changes.

These assumptions may be violated based on punctuated evolution and/or environmental changes (climate, population, extinctions, or gaps in the ecological system) that change the nature of the timing of mutation expression.

C. Yes, using molecular clocks to estimate divergence of species depends on other methods of dating that are relative. Additionally, MC analysis can be modified to look for chemical changes and reactions within the cellular structure.

Part 6 -- It is virtually impossible for a tetraploid plant to interbreed with diploid individuals due to the number of chromosomes within the process of autopolyploid. Diploids have two sets of chromosomes, tetraploids have four sets and are thus incompatible to produce viable offspring.

Part 7 -- Pre-zygotic barriers are also known as prezygotic isolation. They include: 1) temporal or habitat isolation (physical or habitat barriers that change the ecological nature of the species); 2) sexual isolation by behavior or conduct (mating rituals, culture, divergence of belief); 3) mechanical isolation -- change of genital characteristics, estrus, or fertility; 4) gametic isolation -- changes in the actual chemistry of the reproductive cells that does not allow for cross-breeding.

Part 8 -- Species are different kinds of organisms; subspecies are versions of the species. If a yellow warbler myrtle and yellow warbler Audubon can interbreed, they are likely the same or sub-species. Mating, behavior, habitat, diet, and anatomical characteristics can help biologists classify as a single or divergent species.

Part 9 -- Adaptive radiation is the process in which an organism may diversify quite rapidly into a multitude of new forms based on environment niches. In the Hawaiian Islands, for instance, the ocean creates a barrier, as do some of the mountains and volcanos, allowing species of silverswords to adapt rapidly based on diet, climate and habitat. The Big Island is a great example of this; dry and volcanic on one side; tropical and vegetative on the other. On a mainland environment, this adaptive radiation could occur again based on geologic or natural barriers that make it difficult for species to extend beyond their own habitat. Microhabitats can, and often do, create rapid adaptive variation.

Part C. Species 2, 4 and 5

Part 13 - In vitro evolution may not involve the cells and therefore the results can have larger mutations; Molecular evolution is at the RNA, DNA and protein scale based on cellular structures. In vitro evolution produces new molecules, molecular evolution new combinations.

Part 14 -- Between fossil and molecular evidence, I would side with the molecular evidence due to the reliability of science and genetic definitions as opposed to outside variables (temperature, strata, location, etc.) of the physical fossil evidence.

Part 15 -- Silent mutations are DNA mutations that do not result in changes to the amino acid sequences, or that do result in amino acid changes but not radically different properties of this change. These can occur in non-coding areas, or in positions that do not alter the behavior of the amino acid in coding for proteins.