Daily Newsltter

October 26, 2012

Mendel, Meiosis and Evolution

With meiosis we see the mechanism of inheritance first hinted at by Mendel. Gregor Mendel discussed how each person has two "copies" of the information that gives rise to a physical trait (genes), and that there were variations in that information which gave rise to different expressions of these traits (alleles).

Mendel's work gave biologists an understanding of inheritence, and an understanding of chromosomes and nuclear division helps to understand Mendel's inheritence model and the variations of that model. With cross-over in Prophase I, and the random seperation of homologs in Anaphase II, we can see the recombination of parental genes that result in genetically unique gametes (sperm and egg). This results in genetically unique individuals each generation.

Diversity is one of the greatest advantages of sexual reproduction. While >99% of our genes are held in common within a species, there is sufficent genetic variation to allow provide a species with a broad adaptaion range. Remember, the goal of evolution and survival resides not in the individual, but in the population. Those with genetic, metabolic, or physiological advantage will have a greater chance to leave offspring; thus the species survives and thrives.

In class, I mentioned that when you get to the core of biology, it is ultimately all about sex. Not the physical act, but the concept. The recombination of genes allows for diversity. Some organisms spend most of their life in haploid, or non-sexual reproductive states. They only expend the energy for sexual reproduction when they need to insure the survival of their offspring.

Daily Challenge

Today, you are to reflect upon what you have learned so far regarding metabolism, Mendelian inheritence, and meiosis. Build a picture of evolution based upon the need for a diverse population. Use an example to help illustrate the need for diversity. As a starting point, look to endangered species (why is it a problem when you have few individuals left?) or look at what happens when you have genetically similar trees struck by disease (Pine Bark Beetle infestations).
Link to Forum

Video Challenge

Today, I'm going to give you a video challenge. Below is a link to a video about animal genitalia (penises to be percise). The video is informative, but at times very vulgar (so be warned). The video's narrator makes some interesting, and humorous, comments about evolution.

What you are to do is reflect upon the views of evolution discussed. What insights can you glean from the narrator and the topic, and what errors are made (even jokingly) about evolution.