Due to the high growth rate ability of chytrids, the chytrids should have been able to overwhelm even a large chemotype 1 population and win the Red Queen arms race. However, this did not happen. Instead the CD 2665 relationship between chytrids and chemotype 1 showed stable coexistence. In the research of De Bruin et al. a single chytrid strain was used, which may not be the case in our environmental study. However, the laboratory study was designed to test how host populations responded to parasitic pressure in general in light of the Red Queen theory. The results were that host diversification protected host populations. They concluded that this would cause an arms race with diversification on both sides. The occurrence of two or more chytrid strains will not change the outcome. High parasitic pressure will continue to drive diversification in host population irrespective of whether this pressure is exerted by one or multiple chytrid strains. Quantifying all chytrids that infect Planktothrix is an estimate of this pressure. A decrease in host diversity at a constant parasitic pressure is Cyprodime hydrochloride either showing that the Red Queen theory is not applicable or that the host is increasingly better protected. Our findings indicate that the hypothesis of De Bruin et al. using the Red Queen theory is not upheld in our sediment study. Other factors might have played a role in maintaining chemotype1 dominance over other chemotypes and chytrids. The disease triangle presented by Gsell describes the relationship not only as between parasite—host but also including environmental pressures. Gsell describes the potential environmental stressors that affect both host and parasite but where adaptation to environmental stressors by either parasite or host can lead to increased relative fitness of one over the other. For example, low temperatures in the spring can be used as an advantage by diatoms enabling them a window of opportunity to bloom at a time when chytrids are limited by temperature constraints. The result is to release the diatoms from chytrid infection pressure. Light is another environmental stressor for both chytrids and phytoplankton hosts. Bruning found that there was a significant decrease in zoospore production on a light limited host. In the 1990s Kolbotnvannet Planktothrix changed habitat from the epilimnion to the metalimnion, at a time when nutrient and chlorophyll a concentrations in the lake had decreased allowing light to penetrate deeper into the water column. This shift downward by Planktothrix during periods of increasing light penetration is a common and a routinely found event around the world and not indicative of light limitation. Planktothrix in the metalimnion can take advantage of the environmental constraints of low light and lower temperatures on chytrid infection rates to increase growth. The ability to utilize low light levels could then be also viewed as a positive environmental adaptation by Planktothrix to avoid chytrid infection.