How to Identify Species

Analogous & Homologous Structures

The author of this report is asked to answer several questions about anatomical features. Namely, the author will be focusing on the difference between analogous and homologous structures. Of course, the assignment describes that these features are instrumental to the proper classification of species. The advance of technology has increased and improved the ability for scientists and biologists in particular to engage in this behavior but it has been a science for quite a while. While some people are under-informed about what analogous and homologous structures and what it all means, the author of this report would deign to educate both the author as well as anyone new to the subject that might read this report,.

Differences Explained

As neatly explained by a website ran and operated by the University of California at Berkeley, homology/homologous structures are those that were inherited from the same common ancestor. For example, eye color in two grandchildren from the same grandparents would be sharing a homologous trait. On the other hand, a sample of analogy (analogous) evolution is when there are similarities due to other factors. This is otherwise known as convergent evolution. As explained by the Berkeley website, convergent evolution is when "two distinct lineages evolve a similar characteristic independently of one another. This often occurs because both lineages face similar environmental challenges and selected pressures" (Berkeley, 2015). For example, blue is a fairly uncommon eye color. If two people have it, it COULD mean it is because of a common ancestor. That would make it a homologous evolutionary result. However, if they do not share a common ancestor, than it is an analogous results. Meaning, it is a matter of correlation rather than causality. The former is when two things happen to occur at the same time (but may or may not be related) and the latter is when one provably and verifiably affects or causes the other (Berkeley, 2015).

As far as an example of a set of species that are supposedly homologous rather than analogous, there would be the Eurasian Magpie and the Australian Magpie. The former of those two is a corvid and the latter of those is not (Christidis & Boles, 2007). This is a bit funny and interesting because they are both birds, they are both magpies and they are quite similar in overall appearance. However, they are in a completely different classification of birds from each other due to the fact that any similarities they have are NOT because they possess a common ancestor (Berkeley, 2015).

The author is now asked to answer the question of how this has affected the current classification system. Indeed, the author of this report would suggest that it just like DNA in people. Indeed, there are people out there that look strikingly alike. Sometimes, the resemblance is so strong that they get mistaken for each other and people insist that they are family members. Indeed, they may have a connection somewhere in their family tree but the DNA profile of the person would almost surely show that while they ended up with much the same characteristics, there is not a familial link that proves that the DNA of one led to the DNA of the other. Indeed, it is just the way that the DNA dice rolled for those two people. Indeed, the author of this report would ponder that there is probably at least one person out there that is not "homologous" to the author yet looks exactly like the author. It can be a hard distinction to make for some but must be learned (Berkeley, 2015).

Reading Assignment

The author of this report has been asked to read the eighth and ninth chapter of the assigned text. Upon doing so, there will be a bit of a taxonomy exercise. It is noted by the assignment that taxonomists try to group organisms together into their correct categories. With that in mind, the author is asked to pretend that the author is a taxonomist and that the author is trying to identify a snake that has been found. It has to be figured out where the snake is a new species or whether it was known about and identified prior by another biologist or other scientist. The author is asked how the author of this report would go about doing this. The author will explain this and more. While the identification of current or new species can be difficult, there is plenty of documentation and procedural frameworks to follow out there when it comes to identifying new species and animals.

Species Identification

Per the information given from the assignment, the snake was found in the northern end of the state of Missouri. Indeed, the snake seems that it might bear a striking resemblance to a snake that has been seen personally by the author at the southern end of Missouri. However, the author of this report notes that the markings of the two snakes, while similar, are not the same. It would be important to first define and quantify what a species truly is when it comes to biology and taxonomy in general. As defined by the same Berkeley site reference before, a species is most precisely defined as a "group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions" (Berkeley, 2015). The university site goes on to show pictures of four spiders that are actually quite different in terms of appearance. However, they could all theoretically interbreed. Thus, they are the same species and this species is known as Theridion Grallator. This is in much the same way that all human beings are homo sapiens and thus could interbreed together if they were to mate. However, the lines of species are not always clean-cut and easy to trace. For example, the Berkeley website talks about the carrion crow and the hooded crow. The question becomes whether the hybrids formed by those two different crows mating should be considered a new species or not or if they are part of the same general pool since they could inter-breed in the first place (Berkeley, 2015).