King Phillip Came Over for Good Spaghetti

I began thinking first about when does a species become a species? Then I got stuck with that idea for the rest of my writing. I have asked this question but wanted to look into it for a more solid definition. I consider If we put two identical animals in different terrains and assume they could survive how long would it take for them to become different species? One definition I have heard states that different species cannot mate or breed with each other. My first thought goes to dogs and squirrels. We have so many different kinds of dogs small to large. If you tell someone who has never seen a dog that a Chihuahua and that Great Dang are the same species they would think you are insane. These cannot be the same animal! Then we see on the other spectrum that we have red squirrels (Sciurus Vulgaris) and gray squirrels (Sciurus Carolinensis) which are similar in many aspects but cannot be considered the same species.

Obviously, if this has to do with the compatibility of breeding then DNA from both organisms but be able to be compatible to some point. We cannot rely only on the morphology of an animal to classify it if this is the case. We do have a varying amount of people with different traits around the world yet we do not classify them as different species. And we have not genetically breed people like we have with dogs to have long ears, small legs, etc. So when you think about it this way it makes sense to say that what makes a species is a lot more complicated than looks.

As I consider this I think about meiosis and what our cells have to do to replicate our DNA and Chromosomes. I think it may have to do with the chromosome number or maybe compatibility between types of chromosomes. We have ours categorized in pairs and know where some of our traits and genes are depending on the chromosome. I have found a case where six different species of Rock-Wallabies having similar genetic material even though they are of six different species. This article mentions that two ways our system tries to manage this speciation are by; 1) underdominance, which causes most hybrids to lose fertility, and 2) recombination suppression, where genes needed for local adaption or life are linked due to less recombination in these segments. I can imagine this may be in segments that may be heavily managed so certain parts of DNA are not changed. As I have looked into this the main constant for speciation has been stability. As organisms genetic code goes forward it is safer to stay constant and avoid mutations or changes because these tend to be disastrous health in many cases.

While we are on the topic of sharing DNA I remember that hybrids are a possibility. Many of us have heard of the Liger which is the mix of a Lion and Tiger. Horses and Donkeys can create mules but these hybrids tend to make offspring that is not fertile. I want to bring up something else that I found which is Coywolves. Coywolves are what some are calling a mix of wolf and coyote, and some news articles state domestic dog DNA is present as well. We see that these two, wolf and coyote, have had dwindling numbers in the past as the environment has changed due to human interaction, but the new hybrid is able to take advantages of both canine species to survive.  It leaves an interesting predicament for those trying to get these animals off the endangered lists. Technically they are no longer dying out but they are changing to something else.

This is what evolution is it seems. In my search to find how genetically or physical changes are defined leading to a definite change in species was difficult. As I have found there are varying definitions of species which does not make it easy. I had hoped to find some mathematical information about how similar DNA is or what amount of chromosomes and traits must be similar to equate to a similar species, but it was not given much mention. As with many things in science, there are exceptions and these change the way we look at things. This is probably for the best since it will open is to more possibilities and allow us to not limit ourselves to one solution. Introducing new traits without issue is something we search for as we move forward in research, and functional hybrids may allow us to figure out more details about how our reproductive process works and this could possibly give hints to how we evolved ourselves.

Sources:

Academic:

Gene flow despite complex Robertsonian fusions among rock-wallaby (Petrogale) species

Sally Potter, Craig Moritz, Mark D. B. Eldridge

Implications of different species concepts for conserving biodiversity

RichardFrankham

Genetic Characterization of Eastern "Coyotes" in Eastern Massachusetts

Jonathan G. Way, Linda Rutledge, Tyler Wheeldon, and Bradley N. White"

Additional:

Rock-wallaby interbreeding causes rethink on evolution

https://phys.org/news/2015-10-rock-wallaby-interbreeding-rethink-evolution.html

Far From Sterile, Some Hybrids May Start New Species

https://gizmodo.com/far-from-sterile-some-hybrids-may-start-new-species-1710126185

Why are different breeds of dogs all considered the same species?

https://www.scientificamerican.com/article/different-dog-breeds-same-species/

Coywolves are Taking Over Eastern North America

https://www.smithsonianmag.com/smart-news/coywolves-are-taking-over-eastern-north-america-180957141/

Yes, Eastern Coyotes Are Hybrids, but the ‘Coywolf’ Is Not a Thing

http://scitechconnect.elsevier.com/eastern-coyotes-hybrids-coywolf/

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