Understanding Evolutionary Processes and Theories
What is the name of the scientific theory that is able to overcome each of the following falsehoods? (Let no one say that no one has seen other species become evidence that this change does not occur). The continents do not move, but you would notice. The theory that allowed it to overcome the fixism of biological evolution (Darwinism). The observation error of fixism is related to the age of the Earth and the concept of geological time. Only when it was on an Earth of many millions of years ago did it start to allow time for evolutionary processes to take place. The theory helped to overcome the fixism of geology (the immobility of the continent) was the motive, first in its “continental drift” by Wegener and finally with the theory of plate tectonics. The observation error in this case was also associated with geological time; the displacement of the continents occurs at a pace slow enough to be negligible unless very precise measurements are made via satellite. Observation of paintings of ancient Egypt shows birds that appeared identical to those currently used by Cuvier as an argument favoring fixism, which is an error behind this false evidence. In the observation of Cuvier, the idea of an Earth about 6,000 years old is implied, for which the 3,000 years since these paintings were made represent half the time available for changes that would have occurred in the species. Your genotype is equal to what you had 10 years ago; what about your phenotype? The genotype itself is the same as it was 10 years ago, but the phenotype has changed. Some films tell stories of people permanently living in an aquatic environment who end up developing gills. Is that true? What is a serious opinion on this story? A Lamarckian would say yes; it is possible that a person could develop gills after several generations under these conditions, as life in the water would generate the need for change in the respiratory system that would adapt to new conditions by the appearance of gills.
Activity 5. Describe the processes occurring in each of the images: Image 1: In a brown beetle population, there is one green beetle. Image 2: Because these beetles live on green leaves, those that mimic the color are less likely to be eaten by predators, while the brown ones are easier to detect. Image 3: The longer survival of the green beetles leads to an increase in their population. Image 4: Green beetles become the most common in the population. This associates with each of the basic ideas of Darwin’s theory represented in the images: Image 1 shows the variations between individuals in a population. Image 2 shows that not all individuals born survive, initiating natural selection in the best-adapted survivors. Images 3 and 4 indicate that those who survive will have offspring and pass on their advantageous variations, leading to gradual changes in the population. Would the evolution of this population of beetles have been different if they fed on the leaves of the soil? The selection would have been reversed, leading to the elimination of the green beetles.
Activity 6. All tips regarding dolphin fins have become the forelimbs of the dolphin itself, which have become flippers. The hind limbs, however, have atrophied, and the caudal fin is newly formed, like the dorsal fin. What are the similarities and differences between the evolutionary processes of the dolphin and seal? In both processes, there is an evolutionary adaptation to the aquatic environment, with the formation of fins and the adoption of a fusiform shape that improves mobility in the water. However, the processes followed in each case are different; in seals, all limbs are transformed into flippers, while this does not occur in dolphins. In other words, the same problem (the need to move swiftly in the aquatic environment) is solved in two different ways, demonstrating that the result of an evolutionary process is never predetermined.
Activity 7. A parasitic fungus attacks tomatoes, and chemicals (fungicides) are used to remove it, but the product will lose effectiveness and may eventually need to be changed. How would a “Lamarckian” explain this? A Lamarckian would say that the presence of the fungicide in fungi has led to changes that have enabled them to adapt gradually and become resistant. A Darwinian would argue that among the initial population of fungi, there were a few resistant to the fungicide. Until then, it was a neutral variation, meaning it did not generate any benefits or drawbacks. The presence of the fungicide introduces a new selection criterion that makes the advantageous variation necessary for survival and reproduction, increasing the percentage of resistant fungi.
Activity 8. Which of these two trees represents gradual evolution, and which follows the pattern of punctuated equilibrium? The tree on the left represents gradual evolution, while the right follows the model of punctuated equilibrium. Which species has been more stable for longer? The most stable was species D. Which species is more closely related to species B? The species most closely related to B is species C. Among the species marked with letters, which are now extinct and which are not? Species G and F have become extinct, while species A, B, C, D, and E are not extinct.
Activity 9. Among the species present, there is a nautilus that has remained stable for many millions of years. Which evolutionary theory explains this fact better: the synthetic theory or punctuated equilibria? The theory of punctuated equilibria would better explain this, as it proposes an evolutionary process with long periods without change, followed by shorter periods with frequent changes.
Activity 10. Locate the weather variables in the image of the flies. The time variable would be at the top. Where is the common ancestor of these three species located? The last common ancestor would be at the point where the tree branches into the different Drosophila species. Below this point, all the ancestors are common to these species, while above it, they are not.
Which species has a greater degree of kinship to D. melanogaster? D. dentissima.
Activity 11. If two populations of the same species are geographically distant, can different criteria of natural selection intervene in the process of speciation? Yes, because the environments can be different, and a mutation may be favorable in one environment and unfavorable in another. Additionally, if communities are remote, they will also differ, introducing different criteria of predation, competition, parasitism, and so on.
Activity 13. What are the differences between the Laetoli footprints and those of a chimpanzee? The Laetoli footprints are much more similar to modern humans than to those of a chimpanzee. The thumb is not behind the other fingers and spreads laterally, but aligns with the other fingers. Do these differences confirm that this hominid was bipedal? Paleoanthropologists have no doubts: the Laetoli hominid walked erect.
Activity 14. What data support that the Man of Flowers is considered a hominid? What is the difference with respect to H. erectus? The Man of Flowers was bipedal and used stone tools; there is no doubt that it was a hominid. Its size was smaller than that of H. erectus, and its cranial capacity was also smaller.
Activity 23. According to these results, do both populations belong to the same species? Why? Yes, because they can crossbreed. Although nothing is said about the offspring of these crosses, the formulation seems to imply that the descendants of crosses between individuals from both populations were fertile. How many matings occurred between males and females of the same population, and how many between different populations? Mating between males and females of the same population was 602, while between males and females from different populations was 302. What might these differences indicate? What might have happened if the populations had been kept separate for longer? These differences suggest that changes in preferences or degrees of affinity between the populations have occurred. If they had been maintained in separation for a longer time, these differences would likely have been accentuated, leading to reproductive isolation between them.
Activity 25. Compare the arrangement of the ends of all of them. Which one would you associate with Lucy? The image on the right. What does this mean regarding the anatomical changes of bipedal locomotion? Bipedalism meant changes in the position of the foramen magnum, changes in the arrangement represented in the hip images of this activity, and changes in the foot, stretching and aligning the thumb parallel to the other toes.
Activity 26. Sort dinosaurs by degree of kinship to modern birds: sauropod, pterosaur, and crocodilian groups. What would be considered dinosaurs? From high to low kinship with modern birds, the order would be: sauropod, pterosaur, crocodilian. The set of dinosaurs that have adapted their hind legs like a bird (under the body, rather than lateral) would include ornithischians, sauropods, and theropods, although some authors also include Archaeopteryx and modern birds.