Your Inner Fish written by Shubin explores the evolution of mankind and animals to uncover the journey through history of the human body. The possibility of how every creature on earth share the same resemblances on certain body parts and function is deeply rooted within our body and fossil records. Ancient records provides a brief insight of who we are and how we got that way, the current human and animal makeup is supported through years of evolving microscopic changes. The fundamental structure of our body is hidden within our past thus the exploration of fossil records gives us an incredible amount of knowledge about ourself. Your Inner Fish seeks to reveal how our body had become the extraordinary living being it is today. The basic idea behind understanding ourself is through means such as fossil record, genes and embryos.
The genetic differences that make humans distinct from other living creature is one of the bigger discussion in Your Inner Fish. The discovery of Tiktallik gives us a glimpse of our history as fish. The main takeaway from this is that ancient events in the history of life can be told through fossil discoveries. The fundamental build up of a creature remained the same despite the changes in the appearance/function of a body structure. With that said, the fundamental design in the skeleton of all animals can be seen especially when we take a look at skulls and backbones. Variations can be recognised when you start noticing close similarities among the different organs and bodies. The process is the same thing of a different version. Take teeth, hair and feather for example, all of it develops from the interaction between an outer sheet of cells and an inner loose layer of cells despite having different function/appearance. The differences in function or appearance of each species doesn’t necessarily mean that every species are mutually exclusive, in fact, there is a common pattern to every skull on earth. A good example is the structure of our jaw which helps us talk and swallow, a profound similarities is seen in sharks and fishes when we look at its gills. The fundamental blueprint of our head is similar to other species which shows the evolution of our species compared to other species, through the years every species developed its own form of unique features. This findings opened up our eyes in how we are related to other species. What’s more interesting about the relationship of other species and humans is that every animal with a body share a version of the Hox gene. The gene is the fundamentally the same in every species but each species has a unique version of the same gene, this helps give bodily structure and organisation(i.e. front and back) to every species.
The later part of this synthesis paper will be covering on topics such as how evolution is connected to the ideas that were presented and highlighted in the book. I will make a connection for topics we have learned in class, particularly about how exactly is the ideas presented in the topic a form of evolution. I want to dive deeper into understanding how different species can be categorised as having remarkable similarities in our structure, function and appearance. The transition from sea creatures to land creatures is something that is often unheard about, to see how evolution is a median that bridged two completely different forms of species.
Before we can go into great depth, we must first understand a few basic concept that are key themes found in YIF. What exactly is evolution? What makes evolution an evolution? What are some mechanisms that bring about evolution that we see? According to yourgenome.org, evolution is the change in characteristics of a species over several generations and relies on the process of natural selection. There are a total of four mechanisms of change that processes for evolution which are natural selection, genetic drift, migration and mutation(Wenzel, 2017). In connection to Your Inner Fish, natural selection has a bigger theme in it so we will discuss more about it as we dig deeper. Mutation is another big part of the themes highlighted in YIF, it is defined as a change that occurs in our DNA sequence(yourgenome.org,2017). This could be mistakes during the replication of the DNA or environmental factors such as UV light and radiation. Variability is described as the tendency of individual genetic characteristics in a population to vary from one another, this could be down to a change in genotype or external factors(Biology-Online Dictionary.2017). This is talked about frequently in YIF especially when it comes to how each species is unique despite having certain key similarities. Heritability is the proportion of a variation in a phenotypic character in a population that is due to individual differences in genotype(Britannica.2014). We will explore more about heritability as we find out more about common traits in the different species. And finally, fitness is defined as a biological condition in which a competing variant is increasing in frequency relative to other competing variants in a population(biology-online.org.2017). This measures the reproductive success of genes passing from one generation to another.
Evolution is part of what Neil Shubin’s findings has been about, a gradual change in each species that had came from a common ancestor. The features of each species may have been completely different now after years of evolving, despite that we still can study the evolutionary patterns among species because of fossil records, genes and embryos(Shubin.2009).The discovery of Tiktallik links between two different kinds of species, the intermediate between fish and land vertebrate. Tiktallik is crossover between a fish and a tetrapod, it has scales on its back(common among fishes) and it has a flat head with eyes on top(common among land living animals). The information gathered pieces the missing links between the transition from fish to the first land vertebrates called tetrapods(Shubin.2009). This gives us details of evolutionary pattern because we can see how closely related sea and land living species are. The head of Tikatallik is free of the shoulders which shares the same arrangement as amphibians, reptiles, birds, mammal and humans. We could trace a similar outline in the arm bones from fishes to humans too, this shows that all of our features could be traced back to fishes. From these two examples, we can already highlight the outline of each species and its commonality to fishes. As noted in our earlier definition of evolution, the characteristics of each species changes over time. So happened the Tikatallik have the transitioning characteristics of sea and land species, evolution takes place because the Tikatallik brought over new characteristics(land features) that weren’t common before. The development of features that are common with land creatures is through evolutionary changes. Not only that, the body outline of every species shows a form of evolutionary pattern too. The fact that certain bone structure and placement are similar from fishes to humans, evolution helps create the distinct pattern we see today. A huge part of this evolution is due to natural selection, which is the adaptability of species to best suit the environment. Natural selection is defined as a process in nature in which organisms possessing certain genotypic characteristics that make them better adjusted to an environment tend to survive, reproduce, increase in number or frequency, and therefore, are able to transmit and perpetuate their essential genotypic qualities to succeeding generations(biology-online.org.2017).With land being more abundant and more habitable for species to live in, it creates evolutionary traits to help species such as the Tikatallik survive in dryer conditions. I personally think that is the case for natural selection, the trait for surviving on dryer conditions is passed on from the Tikatallik to other land living species. We learned in class about the three conditions that is necessary for natural selection to take place(Wenzel.2017). Variation of a trait can be seen in each species, every species’ trait vary from one to another. A good example is the trait for the survival in every species, each species has different ways to adapt/escape from predators. The function is the same but it varies from the way of how well it does it. Heritability is another necessary condition for natural selection to happen, its basically traits being passed on from one generation to another. A perfect example for heritability is the traits passed on from Tikatallik to other land living creatures to adapt to land conditions. Lastly, differential reproductive success in each species is necessary for natural selection to happen. Species that couldn’t adapt to the environment are extinct but those species which have survived through it can pass its gene to the next generation(Wenzel.2017).
Since we know that evolution is dependent on mutation from what we’ve learned in class, how exactly is mutation talked about or described as in YIF? In class, we were told that a build up of mutation can lead to differences in physical appearance or traits. That a variation in a population is caused by random mutation, mutation can be in form of lethal or non lethal which can be passed on to the next generation(Wenzel.2017). The Tikatallik again is a perfect example of how mutation took place and bridge the gap between land and sea creatures. This doesn’t necessary meant that mutation took place for it to be useful in bringing sea and land creatures together. As said earlier, the mutation is a random change that isn’t occurring due to how beneficial it would be for the species(Berkeley.2017).The random change in the DNA sequencing caused a shift in the adaptation of the species to be able to condition itself to the environment. Majority of species we see today are evolved due to a build up of mutation(changes in DNA sequence). The mutational change can cause differences in what species are like and it changes the aspect of the life of a species(Berkeley.2017). We can clearly tell that the mutation in the Tikatallik is changing the aspect for sea and land creatures because it is the only species that bridges the two category of species. But of course we can’t say that the Tikatallik is human’s exact ancestor, but it have a certain extend of relatedness to us when we talk about it on a more precise biological term(Shubin.2009). Despite genetic mutations and bodily changes, we can connect lineages to biological features that we can see. Identifying the biological features can give us a rough idea of the genetic information because every living organisms came from parental genetic information. Every species is a mutated descendent of its ancestors, this is why we have biological similarities to our parents(Shubin.2009). However, we do not share the exact same genetic identification as our parents despite the similarities(Wenzel.2017). There wouldn’t be much variation to the population if we had the exact same genetic information as our parents. Shubin mentioned that knowing how modification works is the key to unlocking the biological history because descent with modification can leave a signature which we can detect. He further added that descent with genetic mutation can build a lineage that we could identify through certain distinct characters. This connects very well with our class lecture about the law of inheritance. There will be a recessive or dominant allele that an individual would receive. The genetic makeup of a person is determined on alleles that dominant or recessive, if the individual gets a dominant allele then that individual will get the trait/characteristics(Wenzel.2017).
When we learned about phylogeny and how it can show the history of life, it shows how we are all share certain commonality to each other and it shows us the evolutionary changes that happens over time(Wenzel.2017). The way speciation had occurred to show the differences in species as time goes on and mutation taking place. The branches in the phylogenies shows the lineage evolving through time and the nodes shows the divergence event which is how speciation takes place(tolweb.org.2004). Specifically in chapter 11 talks about the family trees and the lineage we have with other species. I thought this was interesting because Shubin includes the example of how we share many similarities to polar bears and that the similarities we have with turtles is shorter than the polar bears’. This shows us that polar bears and human share a more recent common ancestor than we do with turtles. This ties exactly with phylogeny that we’ve covered in class, we can determine the relatedness we have with other species. Drawing up a phylogeny on this needs to be consistent and balanced among we compare the differences seen among different species. Shubin further explained that we can use statistical tools to evaluate the characteristic shared by different species.We draw up the phylogeny which has been supported by characteristics we had seen and comparing the genetic information. In class, the methods we learned to construct the phylogeny by involving the sequence of the same gene in multiple species. The morphological data will bring us to a conclusive study that will show that species that are grouped closely will have similar morphological traits to each other(tolweb.org.2004). The connections we share with other species is just remarkable, the illustration done by Shubin in chapter 11 summed it all. Our structure and genetic makeup stretches from jellyfish, worms, to fishes and more! We have relatedness to jellyfish in terms of multicellularity, worms in terms of the body plan and so on. But the main takeaway from this is that we all have similarities that are noted in the phylogenies.
References
- ”What Is Evolution?”. Yourgenome.org. Web. 28 Mar. 2017.http://www.yourgenome.org/facts/what-is-evolution
- ”What Is A Mutation?”. Yourgenome.org. Web. 28 Mar. 2017. http://www.yourgenome.org/facts/what-is-a-mutation
- “Genetic Variability – Biology-Online Dictionary”. Biology-online.org. Web. 28 Mar. 2017. http://www.biology-online.org/dictionary/Genetic_variability
- “Evolution – A-Z – Heritability”. Blackwellpublishing.com. Web. 28 Mar. 2017. https://www.blackwellpublishing.com/ridley/a-z/Heritability.asp
- “Natural Selection – Biology-Online Dictionary”. Biology-online.org. Web. 28 Mar. 2017. http://www.biology-online.org/dictionary/Natural_selection
- Shubin, Neil. Your Inner Fish. 1st ed. London: Penguin, 2009. Print.
- Wenzel, Aaron. March 21,2017. ‘Phylogenies’. Biology 1101 Lecture, Sullivant Hall, The Ohio State University
- Wenzel,Aaron. February 21,2017. ‘Law of Segregation’. Biology 1101 Lecture, Sullivant Hall, The Ohio State University
- Wenzel,Aaron. February 21,2017. ‘Evolution’. Biology 1101 Lecture, Sullivant Hall, The Ohio State University
- “Heritability | Biology”. Encyclopedia Britannica. N.p., 2014. Web. 28 Mar. 2017. https://www.britannica.com/science/heritability
- “Fitness – Biology-Online Dictionary”. Biology-online.org. Web. 28 Mar. 2017.http://www.biology-online.org/dictionary/Fitness
- “Mutations”. Evolution.berkeley.edu. Web. 28 Mar. 2017. http://evolution.berkeley.edu/evolibrary/article/evo_18
- “Tree Of Life: What Is Phylogeny”. Tolweb.org. N.p., 2004. Web. 28 Mar. 2017.http://tolweb.org/tree/learn/concepts/whatisphylogeny.html