INTRODUCTION REWRITE Why Evolution Is True opens up with a quote by Micheal Sher
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Question
INTRODUCTION REWRITE
Why Evolution Is True opens up with a quote by Micheal Shermer, “Darwin matters because evolution matters. Evolution matters because science matters. Science maters because it is the preeminent story of our age, an epic saga about who we are, where we came from, and where we are going” (Coyne XV). Evolution is the ultimate change in/of populations over a period of time through different genetic traits. The concept of evolution also other sciences have been met with various challenges with religious beliefs being one of them. Religious individuals view evolution as a contradiction to their beliefs in there being a creator or the “divine one,” that is since it [evolution] demonstrates the changes in humans and all species also their development over time. Scientists have an understanding that evolution is true since Earth’s geography, genetics, fossil record and other comparative biology is known. It is imperative to understand why evolution is true, like scientists, if one seeks to understand the concept of evolution. Evolution gives humans a better understanding also dispels any myths about our origins.
CHAPTER 1
First one must first understand the different interpretation of the term “theory” as the everyday use and the scientific use of a term that is significant in understanding evolution. In Science a theory is so much more than just a speculation or a guess that something may or may not necessarily be true. The scientific use of the word is well thought-out, based on testable also verifiable predictions dealing with broad scientific concepts to explain the natural world. In order for a theory to gain acceptance it must first be tested multiple times also have more evidence in favor than against it, only then does a theory becomes a “fact” or true (Coyne 16). The Theory of Relativity is one example the text used that was made by Physicist Albert Einstein, “makes specific claims about the speed of light and the curvature of space-time” (Coyne 15). An English Philosopher named William Paley suggested that everything created has a creator; his example was finding a watch and automatically suggesting that it was created by a watchmaker. Darwin originally started pondering the same question that everything has to be created however that was short lived after he attended Cambridge University to become a minister. There he learned a lot about plants and animals which made his curiosity grow, looking much deeper than the “divine creator” theory which ultimately led him to natural selection also evolution. Darwin may not be the first to come up with the notion of evolution but he had copious evidence to support his claims, turning others to dispel the myth and have genuine science. The evolutionary theory, “really consists of six components: evolution, gradualism, speciation, common ancestry, natural selection and non-selective mechanisms of evolutionary change” (Coyne 3). Evolution the first component is how species genetically [through DNA changes] but gradually changed over a period of time also known as mutation. Humans are believed to have evolved from an actual apelike species; humans and whales evolve a lot faster than other species. Other species haven’t changes as much from their ancestral traits which can take hundreds of years (Coyne 4). The gradual change from birds to reptiles over generations is the second component; the concept of gradualism. Adaptation is a factor that slows down the process while evolutionary pressures speed it up. If there are over ten million species how do the many diverse species derive from one ancestor? In the text it gave an example of ancestor X, if it splits to modern snakes and lizards on one side then modern birds also dinosaurian on the other side that means they share the same ancestor “that split into two descendants” (Coyne 6). The common ancestor is unknown to link the reptiles and birds also the ancestor Y to make the carnivorous dinosaurs. Speciation is the third component that does not happen often the formation of the new, diverse species that can’t interbreed. Ancestor X split into different species, when they start evolving also having different environments then the differences become greater. This means the sharing of genes becomes impossible to species of different populations. Looking at the sequencing of DNA now makes it easier to find common ancestry which is the fourth component. One of the biggest components which Darwin shared with naturalist Alfred Wallace was natural selection. Darwin has more ownership since he had detail also what proves a scientific theory which is evidence. This concept is what could shut down the theory of supernatural forces by explaining how natures design came to be. Nothing was made perfect without flaws and had to evolve over time to withstand or survive, reproduce in the environment. Over time the genes that were not suitable for the environment became null and void; diminishing. An example in the text was a once hairless mammoth that eventually evolved into the wooly mammoth [hairier] which made it able to survive also reproduce in the treacherous cold environment; no perfection in natural selection, “it produces the fitter not the fittest” (Coyne 11,13). The last component is other factors that could cause evolutionary changes one of the more important ones is random genetic proportions. This is caused by various numbers offspring created by different families that ultimately lead to change that is uninvolved with adapting. Shubin and his colleagues were looking for fish that transitioned gradually to walking on land; the search was in younger rocks that may discover some diverse fossilized animals. About 385 million years ago they found some [fossilized] amphibians that looked like fish, 365 million years they found amphibians with necks, ears and they also had four legs (Shubin 10). After that discovery they found it was best to then search about 375 million years ago to find the transition or the stage in between 365 and 385 million years ago that link or prove it evolved. Darwin had to come up with clear testable predictions in order to discover and study living also ancient species.
CHAPTER 2
This chapter opens up with an excerpt from On the Origin of Species, “The crust of the earth is a vast museum; but the natural collections have been made only at intervals of time immensely remote” by Charles Darwin (Coyne 20). This chapter helps in gaining a better understanding on how a fossil is produced, decay rates, different fossils linked to evolutionary change also where to find majority of the fossils. In order for fossils to be made there are several steps that must take place. Animals and plant remains would first need to be in the water which is rare that it would include land dwellers. They would next need to end up at the bottom then to protect it sediment would need to be cover it very quickly which is necessary to prevent decay also reducing exposure to scavengers. Since the remains land dwelling animals and plants rarely end up at the bottom of a body of water is the reason why majority of the fossils are marine organisms (Coyne 22). Since only the hard parts of the plants and animals are easily fossilized makes it difficult to have the information needed to know what is needed of ancient species which would come from their soft parts. Looking at how to determine decay rates, geologist utilize radiometric dating which is a tool they use to date rocks also fossils when discovered and there is no reference point to date them. Rocks have radioactive isotopes which decay at different rates so this method helps to know approximately the age on a relative geologic time scale.
Trilobites were arthropods a complex species which are actually classified in grouping with insects and spiders (Coyne 31). This species was able to be studied with their hard shell and are available for purchase since it was normal for them to be found in ancient rocks. Peter Sheldon collected then and found eight distinct ancestral paths which lead to him notice a change, “the number of ‘pygidial ribs’ segments on the last section of the body” (Coyne 31). It was uncertain of the selective pressures that contributed to this evolutionary change as it is unknown to what the environment was like during that time period. There was a need to understand how a vertebrate is able to live on land, the transition [fish to amphibians]; in 2004 when Tiktaalik rosae was discovered. They were considered to be tetrapod’s as they were four-footed with the ability to walk on land, some only in shallow water with similarities to fish but with a neck and ribs which enabled them to breathe on land. The Archaoteryx lithographica was a link between reptiles and birds, more similar to a reptile but about the size of a crow (Coyne 39). This traits this organism shared with reptiles was the jaw consisted of teeth, a tail that was long and bony, also claws also the way the wing had separate fingers. What is interesting about their relation to birds is because the same bones are webbed together instead of being separate fingers. The discovery of feathered dinosaur tetrapod’s found in China around the mid 1990’s; the lake sediments had preserved what most water do not but they were able to see the indentations of the soft parts. The next evolutionary step after the Chinese bird towards flight like turkeys that have short hops in the air is flight. The “trees down” or “ground up” scenario suggests that natural selection will favor the organisms that are able to fly further instead of gliding or leaping; hollow bones also a bigger breastbone to help (Coyne 47). The DNA, pelvis of a whale and also their hind legs will suggest that they descended from land dwelling ancestors. Why would whales land dwelling ancestors go to living in the water? After their ancestors went to land could possibly be linked to the extinction of dinosaurs and their relative marine animals that ate fish. Those marine animals had to compete with other marine mammals for food also possibly ate them. Once the reptilian animals became extinct that left with a sea that had plenty of food also no predators.
CHAPTER 3
The laryngeal nerve evolutionary track could also be known as an imperfect design a “bad design” or maladaptive. Mammals have this recurrent nerve is 3 feet long (longer than it should) it runs from the brain into the larynx which helps humans have a voice also swallow. It is so long that it runs in our chest through the aorta also a ligament that came from an artery then back in order to connect back to the larynx. The path that it takes in humans is similar to that of giraffes but it goes down to the bottom of the neck and back up again. This may be a terrible design since the length enables it to be more susceptible to being damaged; on the other hand the evolutionary design makes sense. Through the evolutionary path after the sixth arch had to move down, “The laryngeal nerve, still behind the sixth arch, had to remain connected to the embryonic structures” (Coyne 84). As other functions had to evolve so did the laryngeal nerve. Features of the human reproduction system also seemed to be roughly constructed. Males’ urethra runs right in the middle of their prostate gland, this creates a disadvantage for them to get hernias. Later on in life males typically, “develop enlarged prostates,” this puts pressure on their urethra which can make urination often painful (Coyne 84). This was the result of mammalian prostates which had evolved from tissues that built in the urethra walls. The birth of children is painful for women which is because the child is passing through the pelvis; this took the lives of many before the creation of modern medicine. Through the evolutionary process the baby’s brain became too large to pass through a narrow pelvis that allows humans to stay bipedal. There is not much room in between the ovary and also the fallopian tube in order to get into the uterus. This came from, “fish and reptilian ancestors, who shed eggs directly from the ovary to the outside of their bodies” (Coyne 85).
CHAPTER 4
Darwin had the biographical evidence theory and it is so strong that many creationists who would normally refute this type of theory could not this time. Even though they could not refute this theory they would rather believe it’s not existent. Noah’s ark was how early “natural theologians” were to explain through religion how animals came to be. This story was practically impossible to explain or prove being that some animals would have needed to have crossed and ocean in order to get to their current home or habitat. Some other reasons it would be hard to prove is how predators were aboard this boat with their prey for six weeks without eating them and staying nourished, also how this one boat carried all of those animals without being overloaded. Another theory that came about to try to refute this theory [biographical evidence] was that theory that Louis Agasiz made saying that animals did not change, this was actually refuted by the many fossils that were discovered through time. Fossilized seashells were found in the Mountain range in South America [Andes] which meant that it had to once be submerged in waters and this was proof for Darwin (Coyne 89). The next discussion is about the developments that were used to prove how the different species dispersed.
Pg 89-90 Continental Drift & Molecular Taxonomy
How does one explain how marsupial mammal’s also placental mammals are on different continents also different animals altogether but they share features and behaviors? (Coyne 92) This is where convergent evolution is introduced as the pattern that explains this. The pattern of convergent evolution when all three parts of the evolutionary theory are working in conjunction with one another the evidence is when animals or species are in different locations but have the same or similar living condition is extreme biographical evidence. The first is common ancestry an example was the same way some marsupials share features while the placental are different from one another. The second is speciation and example is how common ancestors are the reason for many descendants. The third and final is natural selection which is what has made species able to survive through them adapting to their environment.
CHAPTER 5
Adaptation happened through natural selection and the text used a great example was with mice who have different coat colors one of the light shade and the other of the dark shade. The first thing that needs to happen in this process is that of a variable in which mice that are of the same population would need to have different coat shades in order for the trait to evolve. The next thing would have to be heritability in which some of the variation would need to be changes in the gene. For instance if there was no difference in the genetics then the whoever camouflages (light/dark) better into their background or environment will have a greater chance for survival while the other would not be able to be passed down for the next generation to share which would be no evolutionary change (Coyne 117). Genetic Variation is the last thing that needs to take place where whoever camouflaged and survived would need to produce or affects the possibility of having offspring.
CHAPTER 6
The concept of sexual selection very interesting, as it is responsible for the reason males do not survive as often as the females which is due to sexual dimorphisms. Sexual dimorphisms are the traits that male species use to get the attention of the female species. Sexual selection is necessary for it is, "simply selection that increases an individual's chance of getting a mate" (Coyne 148). The way this happens is in two different ways either the males compete for the female or she gets to choose who she wants. There are also different strategies in which the sexes mate since they both have different number of gametes; which means the females eggs are worth more than the males since they have the ability to produce more offspring. The strategy for selection is important since, "a male's only investment in offspring is his sperm;" this differs from the female where they provide the care of the child also investing more (Coyne 157). If the number of males decline due to death by means of the sexual dimorphisms then there could be a potential decline in the average fitness of the population. "Runaway evolution leads to maladaptive evolution" which could cause a significant decline in the fitness (Sinervo).
CHAPTER 7
The Biological Species Concept (BSC) in the first chapter also the term speciation which is, "the evolution of different groups that can't interbreed" (Coyne 6). This was due to an ancestor splitting into similar but separate species. Biological Species Concept is an explanation for how species form speciation which was discovered by Ernst Mayr and Theodosius Dobzhansky. BSC is species of a population that are able to interbreed when "reproductively isolated," occurs when an already existing species split, appearance does not define a species (Coyne 172). One example from the text is when they studies fruit flies two different species that were isolated from their natural habitat now in a volcano. The first species was located in the upper area while the other at the bottom. When analyzing the two species their courtship was different, when crossed it's rare that they mate. Whenever they did mate, the male offspring were sterile, few offspring were made due to inefficient fertilization also no genes were exchanged.
CONCLUSION
While the idea of evolution has caused many social also cultural resistance and it is undeniable true. This is due to the scientific understanding of the fossil record, comparative biology also genetics. Learning about the theories that have proven facts such as all of the biographical evidence to understand how many different species came to be also dispersed should be one of the major things to consider when refuting the idea of natural selection. Now with having the knowledge of how humans, whales and other species existence and traits that have evolved also passed down should help anyone realize that Evolution is true.
Explanation / Answer
INTRODUCTION
The influential work by Jerry A. Coyne, ‘Why Evolution Is True’ starts with a quote by Micheal Shermer, “Darwin matters because evolution matters. Evolution matters because science matters. Science matters because it is the preeminent story of our age, an epic saga about who we are, where we came from, and where we are going” (Coyne, 2009, 15). Evolution is the gradual change in a certain population over a long period through different genetic traits. The concept of evolution though scientifically rooted, has faced numerous challenges especially from religious beliefs. Various religion view evolution as a contradiction to their beliefs of a creator or the “divine power”. It is because evolution demonstrates the changes in humans as well as other species over time as a result of natural selection and not of any divine intervention. Scientific agreement over evolution has been based on the earth’s geography, genetics, fossil record and other empirical evidence. As scientists, it is important to understand why evolution is scientifially accurate, if one seeks to understand the concept of evolution. Evolution gives humans a better understanding also dispels any myths about our origins. This book helps to obtain that scientific understanding.
CHAPTER 1
The first chapter tries to explain the different interpretation of the term “theory”. The everyday use and the scientific use of a term significantly impacts the understanding of evolution. In Science a theory is much more than just a speculation or a guess. The scientific use of the word is well thought-out, based on empirical evidences and verifiable predictions. It relies on broad scientific concepts to explain the natural world. In order for a theory to gain acceptance it must first be tested multiple times also have more evidence in favor than against it, only then does a theory becomes a “fact” or true (Coyne, 2009, 16). The Theory of Relativity is one example the author use. It was proposed by Physicist Albert Einstein, “makes specific claims about the speed of light and the curvature of space-time” (Coyne, 2009, 15). An English Philosopher named William Paley suggested that everything created has a creator; his example was finding a watch and automatically suggesting that it was created by a watchmaker.
Darwin originally started pondering the same question that everything has to be created. However that belief was short lived as he attended Cambridge University to become a minister. There he learned a lot about plants and animals which made his curiosity grow, looking much deeper than the “divine creator” theory which ultimately led him to natural selection and evolution. Darwin may not be the first to come up with the notion of evolution but he had copious evidence to support his claims, turning others to dispel the myth and prove genuine science. The evolutionary theory, in essence, consists of six components: ‘evolution, gradualism, speciation, common ancestry, natural selection and non-selective mechanisms of evolutionary change’ (Coyne, 2009, 3). Evolution the first component is how species genetically [through DNA changes] but gradually change over a period of time. This process is also referred to as genetic mutation.
Humans are believed to have evolved from an actual apelike species; humans and whales evolve a lot faster than other species. Other species haven’t changes as much from their ancestral traits which can take several thousands of years (Coyne, 2009, 4). The gradual change from birds to reptiles over generations is the second component; the concept of gradualism. Adaptation is a factor that slows down the process while evolutionary pressures speed it up. If there are over ten million species how do the many diverse species derive from one ancestor? In the text it gave an example of ancestor X, if it splits to modern snakes and lizards on one side then modern birds also dinosaurian on the other side that means they share the same ancestor “that split into two descendants” (Coyne, 2009, 6). The common ancestor is unknown to link the reptiles and birds also the ancestor Y to make the carnivorous dinosaurs.
Speciation is the third component that is rare resulting in the formation of the new, diverse species that can’t interbreed. Ancestor X split into different species, when they start evolving also having different environments then the differences become greater. This means the sharing of genes becomes impossible to species of different populations. Looking at the sequencing of DNA now makes it easier to find common ancestry which is the fourth component. One of the biggest components which Darwin shared with naturalist Alfred Wallace was natural selection. Darwin has more ownership since he had detail also what proves a scientific theory which is evidence. This concept is what could shut down the theory of supernatural forces by explaining how natures design came to be. Nothing was made perfect without flaws and had to evolve over time to withstand or survive, reproduce in the environment. Over time the genes that were not suitable for the environment became null and void; diminishing.
An example in the text was that the hairless mammoth that eventually evolved into the wooly mammoth [hairier] which made it able to survive also reproduce in the treacherous cold environment. There is no perfection in natural selection, “it produces the fitter not the fittest” (Coyne, 2009, 11, 13). The last component is other factors that could cause evolutionary changes one of the more important ones is random genetic proportions. This is caused by various numbers offspring created by different families that ultimately lead to change that is uninvolved with adapting. Shubin and his colleagues were looking for fish that transitioned gradually to walking on land; the search was in younger rocks that may discover some diverse fossilized animals. They found some [fossilized] amphibians that looked like fish, that dated back to about 385 million years ago and another 365 million years they found amphibians with necks, ears and they also had four legs (Shubin 10). After that discovery they realised it was best to then search about 375 million years old fossils to find the transition or the stage in between 365 and 385 million years ago that link or prove it evolved. Darwin had to come up with clear testable predictions in order to discover and study living also ancient species.
CHAPTER 2
This chapter opens up with an excerpt from On the Origin of Species, “The crust of the earth is a vast museum; but the natural collections have been made only at intervals of time immensely remote” by Charles Darwin (Coyne, 2009, 20). This chapter helps in gaining a better understanding of how a fossil is produced, decay rates, different fossils linked to evolutionary change also where to find the majority of the fossils. Fossils go through many phases to reach the current state. Animals and plant remain would first need to be in the water which is rare that it would include land dwellers. They would then need to end up at the bottom so that it gets protected. The sediment would need to be in cover it very quickly to prevent decay and reducing exposure to scavengers.
Since the remains land-dwelling animals and plants rarely end up at the bottom of a body of water is the reason why the majority of the fossils are marine organisms (Coyne, 2009, 22). Since only the hard parts of the plants and animals are easily fossilised makes it difficult to have the information needed to know what is needed of ancient species which would come from their soft parts. Looking at how to determine decay rates, geologist utilises radiometric dating which is a tool they use to date rocks also fossils when discovered and there is no reference point to date them. Rocks have radioactive isotopes which decay at different rates, so this method helps to know approximately the age on a relative geologic time scale.
Trilobites were arthropods which are a complex species classified in a grouping with insects and spiders (Coyne, 2009, 31). The scientists were able to study this species with their hard shell as they are available for purchase openly since it was normal for them to be found in ancient rocks. Peter Sheldon collected then and found eight distinct ancestral paths which lead to him notice a change, “the number of ‘pygidial ribs’ segments on the last section of the body” (Coyne, 2009, 31). Scientists were uncertain of the selective pressures that contributed to this evolutionary change as it was the environment during that period was unknown. There was a need to understand how a vertebrate can live on land, the transition [fish to amphibians]; in 2004 when Tiktaalik rosae was discovered. They were considered to be tetrapod’s as they were four-footed with the ability to walk on land, some only in shallow water with similarities to fish but with a neck and ribs which enabled them to breathe on land. The Archaeopteryx lithographica was a link between reptiles and birds, more similar to a reptile but about the size of a crow (Coyne, 2009, 39). The traits that this organism shared with reptiles was the jaw consisted of teeth, a tail that was long and bony, also claws also the way the wing had separate fingers. What is interesting about their relationship to birds is because the same bones are webbed together instead of being separate fingers.
The discovery of feathered dinosaur tetrapod’s found in China around the mid-1990’s; the lake sediments had preserved what most waters do not, but they were able to see the indentations of the soft parts. The next evolutionary step after the Chinese bird towards flight like turkeys that have short hops in the air is flight. The “trees down” or “ground up” scenario suggests that natural selection will favour the organisms that can fly further instead of gliding or leap; hollow bones also a bigger breastbone to help (Coyne, 2009, 47). The DNA, pelvis of a whale and also their hind legs will suggest that they descended from land-dwelling ancestors. Why would whales land-dwelling ancestors go to living in the water? After their ancestors went to land could be linked to the extinction of dinosaurs and their relative marine animals that ate fish. Those marine animals had to compete with other marine mammals for food also possibly ate them. Once the reptilian animals became extinct that left with a sea that had plenty of food also no predators.
CHAPTER 3
The laryngeal nerve evolutionary track could also be known as an imperfect design a “bad design” or maladaptive. Mammals have this recurrent nerve 3 feet long (longer than it should) it runs from the brain into the larynx which helps humans have a voice also swallow. It is so long that it runs in our chest through the aorta also a ligament that came from an artery then back to connect back to the larynx. The path that it takes in humans is similar to that of giraffes, but it goes down to the bottom of the neck and backs up again. This may be a terrible design since the length enables it to be more susceptible to being damaged; on the other hand, the evolutionary design makes sense. Through the evolutionary path after the sixth arch had to move down, “The laryngeal nerve, still behind the sixth arch, had to remain connected to the embryonic structures” (Coyne, 2009, 84). As other functions had to evolve so did the laryngeal nerve. Features of the human reproduction system also seemed to be roughly constructed. Males’ urethra runs right in the middle of their prostate gland; this creates a disadvantage for them to get hernias. Later on in life males typically, “develop enlarged prostates,” this puts pressure on their urethra which can make urination often painful (Coyne, 2009, 84). This was the result of mammalian prostates which had evolved from tissues that built in the urethra walls. The birth of children is painful for women which is because the child is passing through the pelvis; this took the lives of many before the creation of modern medicine. Through the evolutionary process, the baby’s brain became too large to pass through a narrow pelvis that allows humans to stay bipedal. There is not much room in between the ovary and also the fallopian tube to get into the uterus. This came from, “fish and reptilian ancestors, who shed eggs directly from the ovary to the outside of their bodies” (Coyne, 2009, 85).
CHAPTER 4
Darwin had the biographical evidence theory, and it is so strong that many creationists who would normally refute this type of theory could not this time. Even though they could not refute this theory, they would rather believe it’s not existent. Noah’s ark was how early “natural theologians” were to explain through religion how animals came to be. This story was practically impossible to explain or prove to be that some animals would have needed to have crossed an ocean to get to their current home or habitat. Some other reasons it would be hard to prove is how predators were aboard this boat with their prey for six weeks without eating them and staying nourished, also how this one boat carried all of those animals without being overloaded. Another theory that came about to try to refute this theory [biographical evidence] was that theory that Louis Agassiz made saying that animals did not change, this was refuted by the many fossils that were discovered through time. Fossilized seashells were found in the Mountain range in South America [Andes] which meant that it had to be once submerged in waters and this was proof for Darwin (Coyne, 2009, 89). The next discussion is about the developments that were used to prove how the different species dispersed.
Pg 89-90 Continental Drift & Molecular Taxonomy
How does one explain how marsupial mammal’s also placental mammals are on different continents also different animals altogether, but they share features and behaviours? (Coyne, 2009, 92) This is where convergent evolution is introduced as the pattern that explains this. The pattern of convergent evolution when all three parts of the evolutionary theory are working in conjunction with one another the evidence is when animals or species are in different locations but have the same, or similar living condition is extreme biographical evidence. The first is common ancestry an example was the same way some marsupials share features while the placental is different from one another. The second is speciation and example is how common ancestors are the reason for many descendants. The third and final is a natural selection which is what has made species able to survive through them adapting to their environment.
CHAPTER 5
Adaptation happened through natural selection, and the text used a great example was with mice who have different coat colours one of the light shade and the other of the dark shade. The first thing that needs to happen in this process is that of a variable in which mice that are of the same population would need to have different coat shades for the trait to evolve. The next thing would have to be heritability in which some of the variation would need to be changed in the gene. For instance if there was no difference in the genetics then the whoever camouflages (light/dark) better into their background or environment will have a greater chance for survival while the other would not be able to be passed down for the next generation to share which would be no evolutionary change (Coyne, 2009, 117). Genetic Variation is the last thing that needs to take place where whoever camouflaged and survived would need to produce or affects the possibility of having offspring.
CHAPTER 6
The concept of sexual selection very interesting, as it is responsible for the reason, males do not survive as often as the females which are due to sexual dimorphisms. Sexual dimorphisms are the traits that male species use to get the attention of the female species. Sexual selection is necessary for it is, "simply selection that increases an individual's chance of getting a mate" (Coyne, 2009, 148). The way this happens is in two different ways either the males compete for the female, or she gets to choose who she wants. There are also different strategies in which the sexes mate since they both have a different number of gametes; which means the female's eggs are worth more than the males since they can produce more offspring. The strategy for selection is important since, "a male's only investment in offspring is his sperm;" this differs from the female where they provide the care of the child also investing more (Coyne, 2009, 157). If the number of males declines due to death using the sexual dimorphisms, then there could be a potential decline in the average fitness of the population. "Runaway evolution leads to maladaptive evolution" which could cause a significant decline in the fitness (Sinervo).
CHAPTER 7
The Biological Species Concept (BSC) in the first chapter also the term speciation which is, "the evolution of different groups that can't interbreed" (Coyne, 2009, 6). This was due to an ancestor splitting into similar but separate species. Biological Species Concept is an explanation for how species form speciation which was discovered by Ernst Mayr and Theodosius Dobzhansky. BSC is species of a population that can interbreed when "reproductively isolated," occurs when an already existing species split, appearance does not define a species (Coyne, 2009, 172). One example from the text is when they study fruit flies two different species that were isolated from their natural habitat now in a volcano. The first species was located in the upper area while the other at the bottom. When analyzing the two species, their courtship was different, when crossed it's rare that they mate. Whenever they did mate, the male offspring were sterile; few offspring were made due to inefficient fertilization also no genes were exchanged.
CONCLUSION
While the idea of evolution has faced many social also cultural resistance, it is an undeniable truth among the scientific community. It is well supported by the fossil record, comparative biology also genetics. Learning about the theories and assessing the biographical evidence to understand different species have been dispersed should be one of the major factors to consider before refuting the idea of natural selection. Now with having the knowledge of how humans, whales and other species existence and traits that have evolved has been well-established, should help anyone realize that Evolution is true.
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