Sordaria Research Paper
“Meiosis and Genetic Diversity in the Model Organism, Sordaria fimicola”
November 4, 2013
Biology 110- Basic Concepts and Biodiversity Fall 2013
I. Introduction
The Earth is home to various forms of life contributing to the endless biodiversity that we see in our daily lives. In environments around the world there are distinct correlations between the environment and adaptations acquired by the organisms that live there. It has been shown that these adaptations are a result of crossing-over events that occur during meiosis. This exchange of DNA sequences give rise to organisms that will survive successfully in certain environments (Cyr, R. 2002). This is seen clearly on the Slopes of Evolution Canyon …show more content…
Sordaria is an Ascomycota that uses a special spore formation process in reproduction. Ascomycota’s use both meiosis and mitosis division to produce eight spores (asci). These asci are held in a sac called a perithecium or ascus, a fruiting body that rupture and release the ascospores when they’ve reached maturity (Cyr, R. 2002). These spores are easily viewed under a microscope and have mutant strain colors with different patterns that serve as proof of crossover events. Wild-type (black spores) and non-black spores (tan) we used to detect crossing over. The asci can be arranged in 4:4: meaning 4 black spores and 4 tan spores, which indicate no crossing over occurred. Asci can also be arranged with alternating tan and black in groups of two. 2:4:2 arrangements also occur meaning 2 black spores, 4 tan then another 2 black spores. 2:2:2:2 and 2:4:2 are both an indication that crossover has taken place. When spores of the organism were crossed with strains from the same slope and from different slopes, it was found that the crossover frequencies were greater on the South Facing slope rather than on the North Facing Slope (Hass, C. and Ward, A. 2010). These findings led to a correlation between harsher environments and high cross over frequencies and also many questions.
In this experiment, we mimicked the first round experiments of setting up crosses between wild type and spore color strains to examine the changes in cross over frequency of Sordaria under normal, baseline
November 4, 2013
Biology 110- Basic Concepts and Biodiversity Fall 2013
I. Introduction
The Earth is home to various forms of life contributing to the endless biodiversity that we see in our daily lives. In environments around the world there are distinct correlations between the environment and adaptations acquired by the organisms that live there. It has been shown that these adaptations are a result of crossing-over events that occur during meiosis. This exchange of DNA sequences give rise to organisms that will survive successfully in certain environments (Cyr, R. 2002). This is seen clearly on the Slopes of Evolution Canyon …show more content…
Sordaria is an Ascomycota that uses a special spore formation process in reproduction. Ascomycota’s use both meiosis and mitosis division to produce eight spores (asci). These asci are held in a sac called a perithecium or ascus, a fruiting body that rupture and release the ascospores when they’ve reached maturity (Cyr, R. 2002). These spores are easily viewed under a microscope and have mutant strain colors with different patterns that serve as proof of crossover events. Wild-type (black spores) and non-black spores (tan) we used to detect crossing over. The asci can be arranged in 4:4: meaning 4 black spores and 4 tan spores, which indicate no crossing over occurred. Asci can also be arranged with alternating tan and black in groups of two. 2:4:2 arrangements also occur meaning 2 black spores, 4 tan then another 2 black spores. 2:2:2:2 and 2:4:2 are both an indication that crossover has taken place. When spores of the organism were crossed with strains from the same slope and from different slopes, it was found that the crossover frequencies were greater on the South Facing slope rather than on the North Facing Slope (Hass, C. and Ward, A. 2010). These findings led to a correlation between harsher environments and high cross over frequencies and also many questions.
In this experiment, we mimicked the first round experiments of setting up crosses between wild type and spore color strains to examine the changes in cross over frequency of Sordaria under normal, baseline