Species, Speciation and Definitions

    While many people believe that species must look alike in order to be group together, that is not the case. The biological definition of species is members of a population that have the ability to reproduce with each other. This is a simple approach to take when considering species on the base level it is very cut and dry if the organisms can reproduce with each other. One of the issues with this definition is the ability of asexual organisms to reproduce with themselves. If they do not reproduce with other organisms, how do you define a species as more than just the descendants of one ancestor? 

    Another issue with defining species with who they can reproduce with is in the case of ring species, when subspecies of a population all overlap with each other to make a ring and can reproduce with each other except at both ends of the ring population, preventing it from forming a complete ring. This causes the question of where you cut off the speciation if only the two groups don't reproduce with each other, but all the other ones can as they would fall under the biological definition of a species. Finally, one of the last ways that this definition can be challenged is hybrid zones, where two species breed with each other to create a hybrid offspring. In this case the two populations are still considered different species although they reproduced with each other. This point to me is very confusing for how we can define species based on the ability the reproduce. How can we have these areas where two different species are reproducing and still, they are different species. It also makes me question how new species can come about being created. 

    The morphological species concept is the idea of defining a species based on the morphology of the population to determine if they are the same species. I believe that this is not the best way to define a species as many types of species can look very similar but not be the same as they have different traits or characteristics that distinctly separate them. Also, some of the time some organisms
within the same species do not all look alike, 

    The phylogenetic species concept defines species as a group that all descends from a common ancestor and uses data like DNA sequences to help define these species and how they can be divided. One of the issues that I think could arise with this type of definition could be determining how far back you go to find the ancestor. Do you do the same number of years for every species group? Or do you vary depending on that certain species? 

All these different options demonstrate how the issue of defining a species could be a challenge when you are studying diversity of species. If there is not a set definition you could believe that you are examining the same species when in reality you are examining two different ones. It could also have an impact on how we study evolution as we use the evolution of species as an indicator. I believe that the easiest way to study evolution when it comes to species would be to do it based on the biological definition. If you are using this definition, then it would be easier to see how traits are passed down from generation to generation and when mutations or changes occur as you can tell they are all the same species as they were able to successfully reproduce. 

While I understand that these two dinos being used to demonstrate the point might be considered different species, they are just being used as examples. This visual demonstrates how while many species to look similar and can be grouped based on that many do not and are still able to reproduce with each other and continue to evolve through generations. Similarly, if you were to categorize them based on the phylogenetic concept how which of the common ancestors would be chosen for these species?