Microevolution questions and answers
A population has been exposed to a new predator. Describe how natural selection may operate.
When a population becomes exposed to a new predator, natural selection may favour individuals with traits that help them survive. For example, individuals that are faster or better at hiding may have a higher chance of escaping the predator and surviving. These individuals will be more likely to survive and reproduce passing on these beneficial traits to their offspring. Over time, the population may evolve to have more individuals with these survival traits, while those less adapted may become less common.
Q8: FST Prediction
High FST (0.337): Low dispersal ability, long generation time, and small population size.
SHORT ANSWER:
Based on the FST value of 0.337 we can predict that the dispersal ability of this species is likely to be low, meaning individuals are not moving far and wide from their birthplace. This is because a high FST value indicates genetic differentiation among populations, which suggests limited gene flow due to restricted dispersal.
The generation time of this species is likely to be long as higher FST values are usually associated with longer generation times. Long generation times result in slower evolution and genetic differentiation between populations over time.
The population size of this species is likely to be small since higher FST values are often associated with smaller populations that experience more genetic drift than larger ones. Genetic drift refers to random changes in allele frequencies due to chance events like mutations or environmental factors affecting certain individuals more heavily than others.
Explain the Hardy-Weinberg equilibrium theory,
including its assumptions,
and then explain the microevolutionary processes of natural selection, genetic drift, and gene flow.
SHORT ANSWER:
The Hardy-Weinberg equilibrium theory is a principle in population genetics that states that the frequency of alleles and genotypes in a population will remain constant over time under certain conditions.
Assumptions:
No mutation: Genetic variations are not introduced into the gene pool.
No gene flow: There is no migration of individuals into or out of the population.
Large population size: The population is sufficiently large to avoid genetic drift.
Random mating: Individuals do not preferentially mate with relatives or individuals with specific traits.
No natural selection: All individuals have an equal chance of surviving and reproducing, regardless of their traits.
Microevolutionary Processes
Natural Selection: The process by which organisms with favourable traits have higher reproductive success, leading to changes in allele frequencies over time. This process enhances adaptation to the environment.
Genetic Drift: Random changes in allele frequencies within a population, particularly affecting small populations. It can lead to the loss of genetic variation and fixation of alleles in a population, influenced by events like founder effects or population bottlenecks.
Gene Flow: The transfer of alleles from one population to another through migration. Gene flow can introduce new alleles into a population, alter existing allele frequencies, and can help reduce differences between populations, promoting genetic diversity overall.
Name a trait that is a synapomorphy for a phylogenetic group but has been lost in some lineages.
Wings are a synapomorphy for birds as all birds share this characteristics due to a common ancestor that had wings. However, in some descendant lineages, such as penguins, have lost the ability use their wings for flying. Over time, these birds have evolved and adapted to utilise their wings differently, such as birds using their wings for swimming.
Describe one key application of phylogenies.
One key application of phylogenies is in tracking the spread of diseases. By looking at the genetic responses between different strains of a virus or bacteria, scientists can see how the disease spread over time and where new outbreaks came from.
A small number of butterflies gets blown across the ocean and establishes a new population on a remote island. What is the name of the event…
The founder effect. This occurs when a small group of individuals from a large population colonise a new area leading to reduced genetic diversity in the new population. The island population is likely to be left-winged colour diversity than the mainland population because the small group of individuals who arrived on the island would likely only have limited genetic variation, which can reduce variety over time. When the island and mainland populations come back iNto contact, hybridisation is likely to occur. Hybridisation is when two different populations interbreed to produce fertile offspring. So when they mate, their offspring will likely have mixed traits or they may experience problems in reproduction, leading to potential speciation.
What is HGT?
HGT is the process by which organisms exchange genes with each other rather than inheriting them from their parents. This can happen between different species and is common in bacteria. A key example of HGT is in the exchange of antibiotic resistance genes in bacteria. When one bacteria acquires a resistance gene from another, it is able to survive in environments with antibiotics, leading to the spread of antibiotic resistance. HGT is important in evolution because it helps species rapidly acquire new traits, speeding up evolution and adaptation.
Define the term ‘model orgnaims’.
Model organisms are species that have been extensively studied and are usually easy to take care of and grow In a laboratory environment and also have certain experimental advantages. A fruit fly is an example of a model organism. The evolutionary theory that highlights that all organisms share some degree of relatedness and genetic similarity is the main justification for why model organisms are used in research.
Describe the evolutionary trajectory for one key trait that has been important in the evolution of hominins. Include one disadvantage and advantage.
One key evolutionary trajectory in the evolution of hominins is bipedalism or the ability to walk on two legs. Bipedalism evolved gradually over millions of years. Early hominins were likely to be quadrupedal, but over time, certain species began to walk upright. This would have been advantageous for early humans in open environments, as it allowed them to travel longer distances in search of food and resources without expending as much energy compared to quadrupedalism. However, the shift to bipedalism resulted in a less stable form of locomotion. Up right walking requires more balance and the structure of the human lower back and pelvis meant that they were more prone to injury, especially In modern humans.
How did Darwin define natural selection? How do we define it today?
Darwin defined natural selection as the process by which organisms with traits better suited to their environments as more likely to survive and reproduce. Over time, these traits become more common in the population. Today, natural selection is defined more precisely using genetics. It is the process by which alleles that increase organisms fitness become more common the population. It acts on heritable variation and is driven by differential survival and reproduction.
One colour experiences predation. What type of selection would occur? What would the affect be for the frequency of each wing colour in the population?
IN this situtaion, the type of natural selection at play is directional selection. Orange-winged butterflies experience high predation, reducing their chances of survival and reproduction. In contrast, grey-winged butterflies are less likely to be eaten, giving them a survival advantage. Over time, the frequency of alleles for grey-winged butterflies increases while the frequency of orange-winged butterflies decreases. As a result, the population will gradually shift towards more individuals with grey-wings, reflecting the direction of selection, favouring that trait.
Why is understanding evolutionary processes so important to conservation?
An understanding of why evolutionary processes are important conservationists is because it helps us understand how species adapted to their environments and how they may continue to evolve in response to changes in the environment, including human impact. This knowledge can help conservationists guide decisions around which species or individuals are more valuable for maintains genetic diversity and adaptive potential.
What may constrain evolution in response to human induced climate change?
loss of heritable variations, genetic correlations, loss of variation by drift, lack of new mutations
Why can we perform experiments on model species?
Model species share a high degree of relatedness and genetic similarity with humans, particularly in the basic biological responses and molecular mechanisms. This means that genetic and cellular responses observed in these organisms can often be extrapolated to predict similar responses in humans.
Describe the hardy-Webern theory, including its assumptions.
The hardy-weinberg theory is a principle in population genetics that states that the frequency of alleles and genotypes in a population will remain constant over time under certain conditions. The assumptions include:
No mutation - no genetic variation is introduced into the gene pool
No natural selection - all individuals have an equal chance at survival and reproduction regardless of their traits
No gene flow - there is no movement of individuals into or out of the population
Large population size - the population is substantially large enough to avoid genetic drift
Random mating - individuals do not preferentially mate with relatives or individuals with specific traits
Describe the microevolutionary processes:
Natural selection - The process by which organisms with favourable traits have higher chances of reproductive success, leading to change in allele frequency over time. This process enhances adaptation to the environment.
Genetic drift - Random changes in allele frequencies within a population, particularly affects small populations. This can lead to the loss of genetic variation and allele frequencies within a population, influenced by events like founder effects and population bottlenecks.
Gene flow - The transfer of alleles from one population to another through migration. Gene flow can introduce new alleles into a population, alter existing allele frequencies and can help reduce differentiation between populations, promoting genetic diversity overall.
Mutation: Mutations create new alleles in a population which increase genetic diversity. This creates different phenotypes that can be selected for or against by natural selection. Over time, if mutations continue to occur populations can become more diverse.
Non-random mating: Non-random mating occurs when individuals choose mates based on specific characteristics such as physical appearance or behaviour rather than at random. This can lead to assertive mating where similar genotypes mate together increasing homozygosity within a population leading to increased differentiation between populations over time.
Describe the chain of being.
The chain of being was a medieval concept that placed all living things in a hierarchical order, with humans at the top and plants at the bottom. This idea persisted in the 1800s, when naturalists began to observe and categorise organisms based on physical characteristics. In the 1900s, Darwins theory of natural selection gained acceptance as an explanation for how organisms changed over time. However, it did not fully account for genetic variation or the role of chance events in a population. Today evolutionary theory incorporates ideas from molecular and genetic biology that explains how genetic variation drives evolution through natural selection.