Biological Evolution Exam 2

The distribution of genotypes in the sampled population follows the expected proportions under Hardy-Weinberg Equilibrium. In a population that is in Hardy-Weinberg Equilibrium, the frequencies of genotypes remain constant from generation to generation if certain conditions are met, such as no selection, no mutation, no migration, random mating, and a large population size. Since the sampled population's genotype distribution matches the expected proportions, it suggests that the population is in Hardy-Weinberg Equilibrium. Therefore, the answer is true.

Modern humans originated in Africa. This is supported by extensive scientific evidence, including fossil records and genetic studies. The oldest known Homo sapiens fossils have been found in Africa, dating back around 300,000 years. Additionally, genetic studies have shown that all modern humans outside of Africa can trace their ancestry back to a single population that originated in Africa. This supports the theory of the "Out of Africa" migration, which suggests that modern humans first evolved in Africa and then spread to other parts of the world.

Genetic diversity refers to the variety of genetic traits within a population. It is important for the survival and adaptation of a population to changing environments. High levels of genetic diversity provide a larger pool of genetic variations, increasing the chances of individuals having traits that are beneficial for their survival. This allows for better adaptation to environmental changes, resistance to diseases, and overall population stability. Therefore, it is generally true that most natural populations have high levels of genetic diversity.

The phenotype of an organism is determined by both its genotype and its environment. The genotype refers to the genetic makeup of an organism, which influences the traits it inherits. However, the expression of these traits can be influenced by the environment in which the organism lives. Environmental factors such as temperature, light, nutrition, and social interactions can all impact how genes are expressed and ultimately shape the phenotype of an organism. Therefore, the environment plays a crucial role in determining the observable characteristics of an organism.

The two key components of cell theory are that all living organisms are made up of cells and that all cells come from the division of other, pre-existing cells.

In a protein coding sequence, the third position of the codon tends to accumulate the most mutations. This is because the third position of the codon is often referred to as the "wobble position," where there is more flexibility in the genetic code. Mutations in this position are more likely to be synonymous, meaning they do not change the amino acid that is coded for. Therefore, these mutations are often tolerated and can accumulate over time without causing significant changes in the protein's function.

The fact that human populations from Africa have much more mitochondrial diversity than populations from other areas of the world refutes the multiregional hypothesis regarding the origin of modern humans. This is because the multiregional hypothesis suggests that modern humans evolved simultaneously in different regions and interbred, leading to a continuous gene flow between populations. However, the higher mitochondrial diversity in African populations indicates that they have a longer and more diverse evolutionary history, suggesting that modern humans originated in Africa and then migrated to other regions, rather than evolving independently in multiple regions.

Long running selection experiments in E. coli bacteria have shown that mutations, which are the driving force of evolution, are unpredictable. This means that even if two identical evolutionary experiments were conducted, they would have significantly different outcomes. The unpredictability of mutations leads to genetic variations that can result in different adaptations and traits, ultimately leading to different outcomes in the evolutionary process.

The ability of an owl to turn its head 180° around is an adaptation that compensates for the trade-off imposed by good binocular vision. This means that while owls have excellent binocular vision, their eyes are fixed in their sockets, limiting their field of view. By being able to rotate their heads, owls can compensate for this limitation and have a wider range of vision, which is beneficial for their nocturnal lifestyle and hunting.

Polygenic traits are influenced by multiple genes. These genes may interact with each other and with the environment to determine the expression of the trait. Examples of polygenic traits include height, skin color, and intelligence. Unlike pleiotropic traits, which are single genes that affect multiple traits, polygenic traits are influenced by multiple genes. The answer "polygenic" is the correct choice because it accurately describes a trait that is affected by many different genes.

The odds of being genetically identical to a full sibling who is not your monozygotic twin are extremely low. This is because the chances of inheriting the exact same combination of genes from both parents are very slim. With a vast number of possible gene combinations and variations, the likelihood of two siblings being genetically identical without being monozygotic twins is incredibly rare. Therefore, the correct answer is 1 out of 76 trillion.

The statement suggests that having leaves modified into species is an adaptation, but without further information about the specific environment and context, it is impossible to determine whether this is true or false. Adaptations are dependent on the environment, so what may be considered an adaptation in one area could be disadvantageous in another. Therefore, without additional details, it is impossible to make a definitive conclusion.

The genetic code is degenerate, which means that multiple codons can code for the same amino acids. This allows for redundancy in the genetic code and provides a buffer against mutations. If a mutation occurs in a codon, there is a chance that the same amino acid can still be encoded by a different codon. This redundancy helps to prevent drastic changes in the amino acid sequence of proteins, which could have detrimental effects on cellular function.

The bright, aposematic coloration of poison dart frogs is the result of positive frequency dependent selection. This means that the more common a particular coloration becomes in the population, the more advantageous it is for predators to recognize and avoid that coloration. As a result, individuals with the bright coloration have a higher chance of survival and reproduction, leading to an increase in the frequency of that coloration in the population over time.

The unification of natural selection and Mendelian genetics took a long time because Mendel's work on genetic inheritance was largely ignored for nearly 80 years. This means that the significance and relevance of Mendel's findings were not recognized or appreciated, which hindered the integration of his ideas with Darwin's theory of natural selection. The lack of attention towards Mendel's work delayed the understanding and acceptance of the relationship between genetics and evolution.

An example of antagonistic pleiotropy is when a mutation in a gene allows a bacterium to resist an antibiotic, but at the same time, it causes the bacterium to grow slightly slower. This is because the mutation provides a benefit (antibiotic resistance) but also comes with a cost (slower growth). This trade-off is a classic example of antagonistic pleiotropy, where a single gene has multiple effects that are beneficial in one aspect but detrimental in another.

A characteristic, such as height on humans, controlled by many different genes is an example of a polygenic trait. This means that multiple genes contribute to the expression of the trait, and each gene may have a small additive effect on the overall phenotype. In the case of height, there are likely numerous genes involved, each with their own contribution to the final height of an individual.

The three components of a population that must be present for evolution via natural selection are variation between individuals in the population, fitness difference between genetic variants, and some of the variation must be heritable. Variation between individuals allows for different traits to be present in a population, which can be selected for or against based on their fitness. Fitness difference between genetic variants refers to how certain traits may confer advantages or disadvantages in survival and reproduction. Lastly, for natural selection to occur, some of the variation must be heritable, meaning that traits can be passed down from one generation to the next.

The given statement is false. The success of a species is not solely determined by its mutational rate. Other factors such as adaptability, genetic diversity, and environmental conditions also play a crucial role in the success of a species. A lower mutational rate may limit the species' ability to adapt to changing environments and may hinder genetic diversity, which can ultimately reduce its chances of survival and success.

An in/del in the protein coding sequence of a gene would have the largest effect on the phenotype of an organism because it involves the insertion or deletion of nucleotides in the coding sequence. This can cause a frameshift mutation, where the reading frame of the gene is altered, leading to a completely different amino acid sequence being produced. This can result in a non-functional or partially functional protein, leading to significant changes in the organism's phenotype. In contrast, a synonymous substitution in the coding sequence would not change the amino acid sequence, an in/del in the non protein coding sequence may not have a direct impact on protein function, and a missense substitution would only alter a single amino acid in the protein sequence.

The given distribution of genotypes in the population after three years shows a change from the original population. This indicates that evolution has occurred for this gene. The increase in the number of individuals with the Aa genotype suggests that there has been a shift in the gene frequencies, which is a key aspect of evolution. Therefore, the correct answer is true.

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Duplication would be the most likely mutation to lead to the creation of paralogous gene copies. This is because duplication involves the replication of a gene, resulting in multiple copies of the same gene. Over time, these duplicated genes can undergo further mutations and diverge in sequence and function, leading to the creation of paralogous gene copies. In contrast, synonymous substitutions, translocations, and inversions do not directly result in the creation of additional gene copies.

The given equation, (p-3s)2 + 2(p-s)q + q2 = 1, represents a modified Hardy-Weinberg equation that includes the effect of natural selection on a population. In this equation, 'p' represents the frequency of one allele, 's' represents the selection coefficient, and 'q' represents the frequency of the other allele. The equation accounts for the reduction in the frequency of the 'p' allele due to natural selection by subtracting '3s' from 'p'. It also includes the interaction between the 'p' and 'q' alleles through the term 2(p-s)q. Overall, this equation models the effect of natural selection on the genetic makeup of a population.

Mollusks are the best model for the evolution of the complex eye because different species of mollusks have photoreceptors that vary greatly in complexity. This variation in complexity demonstrates some of the intermediate steps from a simple eye to a more complex one. This suggests that mollusks have undergone a gradual evolution of their visual system, making them a suitable model for understanding how complex eyes evolved.

There are four different groups of animals that have independently evolved true flight. These groups are insects, birds, bats, and pterosaurs. Insects, such as bees and butterflies, have developed wings that allow them to fly. Birds have feathers and wings that enable them to fly. Bats are the only mammals capable of sustained flight, thanks to their specialized wing structure. Pterosaurs were flying reptiles that lived during the time of dinosaurs and had wings made of skin. All four of these groups have evolved the ability to fly through separate evolutionary processes.

Inbreeding depression occurs when individuals within a population mate with close relatives, leading to a decrease in fitness and genetic diversity. The population of captive bred lizards that originated from only 8 captured individuals would suffer the most from inbreeding depression. This is because the small founding population size limits genetic variation, increasing the chances of mating between close relatives and the expression of harmful recessive traits. In contrast, the other populations mentioned have either mechanisms (disassortative mating) or larger founding populations (human descendants, bacteria population) that help maintain genetic diversity and minimize the effects of inbreeding depression.

Underdominance is the type of frequency independent selection that is of most interest to scientists studying speciation. Underdominance occurs when individuals with heterozygous genotypes have lower fitness compared to individuals with homozygous genotypes. This can lead to the maintenance of genetic variation within a population and potentially drive the formation of new species. By studying underdominance, scientists can gain insights into the mechanisms and processes involved in speciation.

The best way to assess whether or not two complex structures are homologous is to map the evolutionary origin of the structures onto a well-supported phylogeny. This involves comparing the structures in question to the evolutionary history of related organisms and determining if they share a common ancestor. By analyzing the phylogeny, we can identify patterns of evolutionary relationships and determine if the structures are likely to be homologous or not.

The strength of selection for the beneficial allele has a major impact on the speed at which it will become fixed in a population. If the selection pressure is strong, meaning that the allele provides a significant advantage to the organism's survival or reproduction, it is more likely to spread quickly through the population and become fixed. On the other hand, if the selection pressure is weak, the allele may take longer to become fixed or may not become fixed at all. Therefore, the strength of selection is an important factor in determining the speed of allele fixation.

The allele frequencies can be calculated by dividing the number of alleles by the total number of alleles in the population. In this case, there are 160 AA individuals, which represents 160 x 2 = 320 A alleles. There are 480 Aa individuals, which represents 480 x 1 = 480 A alleles. And there are 360 aa individuals, which represents 360 x 0 = 0 A alleles. Therefore, the total number of A alleles is 320 + 480 + 0 = 800. The total number of alleles in the population is 800 + 800 = 1600. The frequency of A alleles is 800/1600 = 0.5, and the frequency of a alleles is 1 - 0.5 = 0.5.

Polygeny refers to the inheritance of traits that are controlled by multiple genes. When combined with differing environmental effects, this often leads to the development of continuous traits. Continuous traits are characteristics that show a wide range of variation, such as height or skin color, and are influenced by the interaction of multiple genes and environmental factors. This is in contrast to discrete traits, which are controlled by a single gene or a small number of genes and exhibit distinct categories, such as blood type or eye color.

Independent assortment of alleles during meiosis would not violate H-W equilibrium. H-W equilibrium assumes that certain conditions are met, including random mating and no influence of external factors such as natural selection, migration, or small population size. Independent assortment of alleles during meiosis refers to the random distribution of different alleles into gametes, which is consistent with the assumption of random mating. Therefore, it does not disrupt the equilibrium.

A haplotype refers to a set of genetic variations or mutations that are inherited together on the same chromosome. These variations can occur within a single gene or across multiple genes. In the context of the given question, a genetic mutation that may or may not lead to phenotypic diversity can be considered a haplotype because it represents a specific combination of genetic variations that can influence the expression of traits. However, it is important to note that not all haplotypes necessarily lead to phenotypic diversity, as some mutations may be silent or have no observable effect on the phenotype.

Negative frequency dependent selection refers to a situation where the fitness of a particular phenotype decreases as its frequency in the population increases. In the case of male morphotypes in dung beetle species, this means that certain male traits become less advantageous as they become more common. As a result, a balance point is reached where the fitness of each morphotype is equalized, leading to the maintenance of diversity in this behavior. This balance point prevents the fixation of one allele and allows for the coexistence of multiple morphotypes within the population.

The most likely distribution of phenotypes in the next generation would be 375 red flowering vines, 250 pink flowering vines, and 375 white flowering vines. This is because the genotype and phenotype distribution in the current generation is Aa: 500, pink flowers, which means that the pink flowering trait is the most common. Therefore, it is likely that the pink flowering trait will be passed on to a significant portion of the next generation. Additionally, since the current generation has an equal number of AA: 250, red flowers and aa: 250, white flowers, it is likely that these traits will also be passed on in equal proportions to the next generation.

Adaptive mutations that are dominant will not necessarily become fixed more quickly than adaptive mutations that are recessive, even if all other conditions are identical. The fixation of a mutation depends on various factors such as the strength of selection, population size, and genetic drift. Dominant mutations may have a higher chance of being expressed phenotypically, but their fixation is not solely determined by dominance. Recessive mutations can still become fixed if they provide a significant adaptive advantage and are not lost due to genetic drift. Therefore, the statement is false.

The most likely explanation for the pattern observed when comparing the original population of butterflies to the population three years later is that evolution occurred due to an overdominant natural selection force. This means that individuals with heterozygous genotypes had a higher fitness compared to individuals with homozygous genotypes, leading to an increase in genetic diversity within the population. This suggests that the forces driving evolution were not constant and resulted in a change in the population over time.