RachelM

Previously, I had defined a species in terms of the ability to reproduce. However, the eukaryotic definition will not hold true for prokaryotes and researchers are left with interpreting the jargon left after millions upon millions of years of evolution through mutations and horizontal gene transfer (HGT). Hanage, et al. tested several isolates of the Neisseria bacteria: N. meningitides, N. lactamica, and N. gonorrhoeae. What they found ultimately was some “fuzz to the puzz” and delineating between species was almost as good as a guessing game.
A bacterial species has apparently plagued systematists for a long while. Hanage goes on to explain that attempts to define species by DNA extraction have been somewhat futile. Using a multilocus approach may be the best method for resolution. Some labs, however, are using a DNA-DNA hybridization approach as the gold standard, a method which still has its own quarks. The multilocus sequence approach, known as MLST (multilocus sequence typing) may not be so good for highly recombinogenic bacteria but may serve its purpose in the ability to draw the line between distinct species.
So is there such thing as a universal species? What evidence do we have for or against this concept? Ben Stiller once said something along the lines of “if we take away all our differences, we’re really all the same.” How can this line, with Ben Stiller’s infinite wisdom, affect the universal species law? What would you have to take away from the bacteria in order to create a universal species and at what point is it not like the other? The line is becoming more arbitrary once phenotype is taken out of the equation.
In class, we talked about adaptations and different means in which to measure it. We saw that adaptation would increase logarithmically and ultimately would plateau after a certain number of generations. How many generations and the extent of the exponential growth were determined by the environment. I am curious to know if genetic load plays the same role as genetic load in say, a plant. Plants that have a low genetic load run less risk of homozygous mutations or “bad” mutations and may continue to propagate through selfing or apomixes. Plants that have a high genetic load tend to have defenses against self-fertilization, such as preventing pollen tube formation by species with genomes too similar to their own, dioeciously, or even separating the pollen grain from the pistil through space or time. A plant may exhibit any multitude of preventative measures from self-fertilization. To draw a comparison, the genetic load of a bacterium is much smaller. Is there a limit to the number of mutations it can really attain?