The article “ Flight of the Kiwi” will explain how large flightless birds overcame the water barriers and dispersed around the world. Also, the article explores the idea of if the Kiwi bird came first or the egg. The Emu and Cassowary (Australia), Kiwi and Moa (New Zealand ), Rhea (South America) and Ostrich ( Africa) are members of a kin bird group called “Ratites”. The answers were proposed by Australasian scientist through countless research projects and gathering accurate evidence. The concepts of time and continental drift explains the spreading of the ratites.
Gondwana was the supercontinent from the Neoproterozoic until the Jurassic. Ratites are hypothesized to be a prehistoric group that wandering through Gondwana. The mega-continent split apart and all the snippets of land contained some of the Rarities. The rates started to gradually adapt to their new environment while being slowly, diverged away. This idea of Joel Cracraft is supported by the evolutionary tree. The ostriches were the first ratites to separate from the rest of ratites. Also, the Emu and Cassowary have a close relationship because they evolved from Rarities lineage. These two species were separated when Australia detached from Gondwana. Continental drift takes many years. 130 million years ago, Gondwana started fragmenting very slow. This would imply that Ratite lived with dinosaurs for half their history. The genetic similarities between all ratites cause a lack in the credibility of the idea that divergence of Gondwana. Also, the location of the branches of the evolutionary tree was unstable. It was suggested that the Kiwi and Moa evolved in New Zealand from a common ancestor during the continental drift. However, they do not have a recent common ancestor. DNA Analyses by Alan Cooper, Matthew Phillips, and other experts suggest that Kiwi, Emus, Cassowaries are close kin. DNA Analysis of Moa bones suggests that they are more grouped with Tinamous. This relationship of flightless Moa and flighted Tinamou implies that loss of flight happened many times in Ratites population. In contrast, the huge oceanic space separating these species implies that their predecessor expanded by flying. There is a possibility that before evolution occurred Tinamous ancestors glided through Pacific from South America to New Zealand. This lead to the thinking that if Moas did so, why did the other Ratites not do the same?
The continental drift indicated that elephant birds were supposed to be a distant relative of Ratites. With only bones to examine, scientists are unable to make a conclusion about the evolutionary resemblance of elephant birds. The DNA sample was very little because elephant bird bones in Madagascar are vulnerable to warmer climates that quickly deteriorates DNA. The DNA technology advancement helped the team with Kieren Mitchell and Alan Cooper extract blood from an elephant bird fossil. The genes proved that Elephant birds and Kiwis were very kin. Despite being vastly different in appearance and inhabiting being very far away. The distribution of these two close species is flighted scattering. Both species lost their wings and became larger, with the Madagascan genealogy became gargantuan. This idea was further supported by archaic fossil Kiwis recently discovered in New Zealand. Modern-day Kiwis are small, suggesting evolution from a smaller, flighted ancestor. The new genetic data lead to re-evaluated of fossil records because of the appearance of the ancestor species different from the modern-day species. It would be difficult to identify the ancestors of the Ratites. New evidence purpose that the Ratites evolution is more recently and the Rarities were originally small birds. Founders of the various ratite ancestry landed on different continents then underwent evolution. They flew around Gondwana and then lost their wings. The flightless rails thrived in New Zealand and many other islands of Oceania. Many of these islands were geographically isolated, and the existence of very similar but flighted rails indicated that flightlessness occurred recently. On small land masses with no threats and shorter travel distances, flying is inadequate and is metabolically draining and requires delicate wings. The ratites have evolved frequently: wing depletion and increased body size; long legs for running in ostriches, rheas and emus; and pillar-like limbs to reinforce the body of moas and elephant birds. The end-Cretaceous extinction of non-avian dinosaurs may have lead to the evolution of the Ratites by clearing global ecosystems of predators and potential competitors The ancient flighted ratites may have been larger than most of their avian peers, leading to their early evolution.
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It is implied that throughout the evolutionary history of Ratites they had large bodies and eggs. Kiwis were thought to have evolved dwarfism and the egg size remained unchanged. Thus, the egg came first, representing a non-adaptive evolutionary delay. A non-adaptive evolutionary is a modification in the allele frequency that that does not occur by itself causing a population to become more adapted to their environment; the causes are a mutation, genetic drift, and gene flow. However, this idea was wrong because Kiwis, like other living ratites, evolved from flighted ancestors, and have always been small. These flighted Kiwi ancestors would not be burdened by large eggs. The large Kiwi egg is probably due to a recent adaptation to their environment. In stable, habitats with fewer competitors, reproduction prosperity is maximized by investing in fewer, stronger offspring. The baby kiwi hatches from its egg, gain energy from an enlarged yolk sac for a couple of days, then becomes independent. Therefore, the small kiwi perhaps came first, and its enormous egg was a later adaptation.
Concepts
This article explores the numerous concepts and terminology of Evolution. One of the concepts is Darwin’s observation about Species varying globally, but there are some similarities is demonstrated in Ratites. One of the examples of this observation mentioned in the class was about Rheas, Emus, and Ostriches having similarities. In the article, it mentions that Ratites inhabit in the different continent but the common traits. For example, the long legs of Ostriches, Rheas, and Emus allow these species to run faster. Furthermore, the Ratites ancestor had wings that were once useful but due to fewer predators, small distance to travel, inefficient of flying and metabolic draining no longer require this function. The modern-day Ratites no longer have wings due to the loss of its original function over periods of evolution. This is an example of a vestigial structure. Another concept is the Cretaceous extinction which might have lead to the evolution of Ratites. Due to the extinction of non-avian dinosaurs, the big predator and other competitors Ratites may have evolved.
The concept of the evolutionary tree is used to support the hypothesis of continental rifting. For example, the idea of “continental rafting” by Joel Cracraft was supported by an evolutionary tree. Moreover, the concept of DNA evidence plays a vital role in this article. For example, the DNA of Moa bones suggested that Moas and Tinamous have a recent common ancestor. Another example is the genetic code of Elephant Birds are similar to Kiwis. The genetic data lead to the analyzation of the fossil history of all living Ratites. The concept of the Founder's Effect is demonstrated in Ratites. The founder of the different Rarities landed on new land and after arrival, they lost their wings. This is probably due to the founders only carrying some of the alleles of the original population’s gene pool. The founders probably carriers of a recessive allele or mutated gene which lead to the loss of wings. The convergent evolution of the Rarities of separate continent demonstrates evolution through natural selection which cause similar structure and appearance form in around the world. Moreover, the concept of allopatric speciation occurred in Ratites due to the geological separation of Gondwana. After the geographical barriers, the Ratites adapted to their new environments and, over time they evolved into different species. For example, the Elephant birds and Kiwis have a recent common ancestor. During the Gondwana separation, these species became isolated and adapted to new their environment. It is similar to Darwin Finches that got blown away to uninhabited land then adapted to their new environment and, over time evolved into new species. but Another concept that can be considered adaptive radiation of the Pacific island Rails. The ancient Rails colonized the Pacific islands and adapted to their distinct environment. The flight rails flew to the islands that were isolated from other lands. This suggests that these species colonized this area, new species of Rills family formed, and gaining new traits and adapted to their environment. Adaptation is a vague concept that vital role in the Rarities. The adaptation of Kiwi birds in New Zealand leads to Kiwis large egg. The adaptation Moas and Elephant bird to there environment lead their pillar-like limbs which support the body. Due to the adaptation to their new environment after the geological separation, the Rarities were able to thrive. Fossil Records was essential for the research regarding the flightless birds. Fossil records were helpful to prove the hypothesis that involve extinct species. Due to the fossil record of the Elephant bird bone allowed the gathering of DNA evidence which proved that Kiwis and Elephant. Divergent evolution is demonstrated due to the Gondwana parting the ancient Rarities gradually evolved to their new environment and evolved into different species. Natural selection is one of the main concepts of this article. The selective pressure that occurred after the non-avian dinosaurs became extinct the Rarities main predator. The decrease in predator leads to an increase in resources and reproduction. Like when there is reduced light in an area, the plant’s living in that area will have to compete and grow taller to get the light. The “fittest” of these species had a desirable trait that allowed them to survive and reproduce. Due to natural selection, the modern-day rarities formed and continue to thrive in their habitat.
Relevance
This article is relevant to many different people. The article solved the long-standing questions that biologist researched for decades on how did flightless birds end up all over the world? and why is the Kiwis egg so large? Also, the answers enhances scientists and researchers knowledge about evolution and the application evolution of different species. This research and article may motivate people to become biologists to study ancient species and solves mysteries about evolution. It may encourage other biologists to look and ancestral history and evolutionary concepts of other species. The article may lead to further research due to the genetic data of the modern-day ratites needs to be reevaluated because it does not support current genetic data of most paleontology. This may lead to the study of what leads to Rarities surviving the Cretaceous extinction? and are Rarities relatives of the dinosaurs since they lived in the same time period? Readers can get a better understanding of evolutionary concepts in real life situations. Also, this article shows the importance of fossil records and the use of DNA evidence. If the fossil records were not present we would be able to know that Kiwi bird and Elephant birds are close kin. DNA evidence proved that the genetic code of Elephant Birds are similar to Kiwis even though they are very different species. With bone work, only scientists were unable to resolve the evolutionary relationship of Elephant birds. The DNA evidence allowed the scientist to make a conclusion about the Elephant Birds. Lastly, the article demonstrated that research can be inaccurate because fossil records suggested the Kiwi and Moa evolved from an ancestral ratite. However, DNA evidence proved that moas were actually most closely related to tinamous. In conclusion, this article is relevant and important to modern day science and the study of evolution.
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