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In biological contexts, polymorphism is characterized by the presence of multiple distinct forms or phenotypes within a species population, not exclusively one.
Answer: False
Polymorphism denotes the existence of two or more distinct morphs or alternative phenotypes within the population of a species, not exclusively one form.
The strict definition of polymorphism requires that the different forms coexist within the same habitat, not that they are geographically separated.
Answer: True
A key criterion for classifying a variation as polymorphism is that the different forms must inhabit the same geographical area (habitat) simultaneously.
Polyphenism and genetic polymorphism are interchangeable terms describing the same phenomenon.
Answer: False
Polyphenism and genetic polymorphism are distinct concepts; polyphenism refers to environmentally induced phenotypic variation from a single genotype, whereas genetic polymorphism arises from genotypic differences.
The term polymorphism is exclusively applied to individual organisms and not to colonial ones.
Answer: False
The concept of polymorphism is applicable to both individual organisms and colonial organisms, where it can describe variations in specialized structures or individuals within the colony.
Monomorphism implies the existence of exactly two distinct phenotypes within a population.
Answer: False
Monomorphism signifies the presence of only a single form or phenotype for a particular trait within a population, contrasting with dimorphism (two forms) or polymorphism (multiple forms).
Polymorphism can include traits that exhibit continuous variation, such as body weight.
Answer: False
Polymorphism is specifically concerned with discrete or discontinuous variations, not traits that exhibit continuous variation, such as body weight.
A variation is considered a polymorphism if the least common morph occurs at a frequency of less than 0.5%.
Answer: False
For a variation to be classified as a polymorphism, the frequency of the least common morph must be substantial, typically considered to be greater than 1%, not less than 0.5%.
The term 'morph' is a formal taxonomic rank recognized under the International Code of Zoological Nomenclature (ICZN).
Answer: False
While 'morph' is a common term for a distinct form within a polymorphism, it is not a formal taxonomic rank recognized under the ICZN; related terms like 'morpha' have specific, limited usage.
The definition of polymorphism requires that the different morphs are reproductively isolated from each other.
Answer: False
The definition of polymorphism requires that the different morphs belong to a single, interbreeding (panmictic) population, not that they are reproductively isolated from each other.
Polymorphism is exclusively a phenomenon observed in animals.
Answer: False
Polymorphism is not exclusively observed in animals; it is a widespread phenomenon found across various taxa, including plants, fungi, and microorganisms.
Polymorphism is primarily studied using only field observations, with laboratory genetic analysis being irrelevant.
Answer: False
The study of polymorphism employs a range of methodologies, including both extensive field observations and detailed laboratory genetic analyses, as both are crucial for understanding its mechanisms and implications.
Which of the following best defines polymorphism in a biological context?
Answer: The occurrence of two or more distinct morphs or phenotypes within the same population, habitat, and time.
Polymorphism in a biological context is defined as the occurrence of two or more distinct morphs or phenotypes within the same population, inhabiting the same area at the same time, and belonging to a panmictic population.
What is the key difference between genetic polymorphism and polyphenism?
Answer: Genetic polymorphism arises from different genotypes, while polyphenism involves different phenotypes from the same genotype due to environmental factors.
The key distinction between genetic polymorphism and polyphenism lies in their genetic basis: genetic polymorphism arises from different genotypes producing different phenotypes, whereas polyphenism involves a single genotype producing different phenotypes in response to environmental factors.
Which condition must be met for different forms within a species to be classified as polymorphic?
Answer: The forms must occupy the same habitat simultaneously and belong to a panmictic population.
For forms within a species to be classified as polymorphic, they must coexist in the same habitat simultaneously and belong to a single, interbreeding (panmictic) population.
What does the term 'monomorphism' signify?
Answer: A species exhibiting only a single form or phenotype for a particular trait.
The term 'monomorphism' signifies that a species or population exhibits only a single form or phenotype for a particular trait.
Why are geographical races excluded from the strict definition of polymorphism?
Answer: They inherently involve different locations, violating the same-habitat requirement.
Geographical races are excluded from the strict definition of polymorphism because polymorphism requires the coexistence of different morphs within the same habitat, whereas geographical races are inherently separated by location.
Which of the following is NOT considered a primary mechanism that can cause polymorphism?
Answer: Continuous variation driven by multiple small additive genes.
Continuous variation driven by multiple small additive genes is not considered a primary mechanism for polymorphism, which typically involves discrete forms. Primary mechanisms include genetic determination, conditional development strategies, and mixed development strategies.
What is the significance of the frequency of the least common morph being 'too high to be solely attributed to new mutations'?
Answer: It is a criterion suggesting the variation is a true polymorphism maintained by other mechanisms.
The significance of the least common morph's frequency being too high to be solely attributed to new mutations is that it suggests the variation is a true polymorphism maintained by other evolutionary mechanisms.
Which of the following is NOT a characteristic required for a variation to be classified as polymorphism?
Answer: The least common morph having a frequency below 1%.
A frequency of the least common morph being below 1% is NOT a characteristic required for polymorphism; rather, it must be greater than 1% to be considered a true polymorphism.
What is the approximate frequency guideline for the least common morph to be considered part of a polymorphism?
Answer: Greater than 1%
The approximate frequency guideline for the least common morph to be considered part of a polymorphism is greater than 1%.
Which term describes the presence of exactly two distinct forms or phenotypes within a species?
Answer: Dimorphism
The term 'dimorphism' describes the existence of precisely two distinct forms or phenotypes within a species or population for a specific trait.
Balanced polymorphism describes a situation where one form is gradually being replaced by another.
Answer: False
Balanced polymorphism refers to the stable maintenance of multiple forms within a population over time, rather than a gradual replacement of one form by another, which would characterize transient polymorphism.
Heterozygote advantage (heterosis) is a mechanism that can lead to transient polymorphism.
Answer: False
Heterozygote advantage (heterosis) is a mechanism that typically leads to the stable maintenance of polymorphism (balanced polymorphism), not transient polymorphism, as it favors the persistence of multiple alleles.
Frequency-dependent selection occurs when the fitness of a phenotype is independent of its prevalence in the population.
Answer: False
Frequency-dependent selection occurs when the fitness of a phenotype is directly dependent on its prevalence within the population, often favoring rarer morphs and thus maintaining polymorphism.
Which mechanism maintains genetic polymorphism when heterozygotes have a higher fitness than either homozygote?
Answer: Heterozygote advantage (heterosis)
The mechanism that maintains genetic polymorphism when heterozygotes possess higher fitness than either homozygote is known as heterozygote advantage, or heterosis.
What does 'balanced polymorphism' refer to?
Answer: The maintenance of different phenotypes within a population over time.
'Balanced polymorphism' refers to the stable maintenance of different phenotypes within a population over extended periods, often due to balancing selective pressures.
How does frequency-dependent selection contribute to maintaining polymorphism?
Answer: It makes the fitness of a morph dependent on its prevalence, often favoring rarer morphs.
Frequency-dependent selection contributes to maintaining polymorphism by making the fitness of a morph dependent on its prevalence, often favoring rarer morphs and preventing any single morph from dominating.
Geneticists use the term 'genetic polymorphism' to refer exclusively to variations that result in visible phenotypic differences.
Answer: False
While often associated with phenotypic variation, the term 'genetic polymorphism' in genetics can also refer to variations at the allelic level (e.g., SNPs) that may not always manifest in observable phenotypic differences.
Genetic polymorphism is characterized by the phenotype being determined solely by environmental factors.
Answer: False
Genetic polymorphism is characterized by phenotypes determined by underlying genetic differences (genotypes), whereas phenotypes determined solely by environmental factors from a single genotype are termed polyphenism.
Supergenes are single genes that influence multiple unrelated traits.
Answer: False
Supergenes are not single genes but rather groups of closely linked genes inherited together as a unit, often controlling complex polymorphic traits.
Pleiotropism describes the interaction between different genes to modify trait expression.
Answer: False
Pleiotropism describes the phenomenon where a single gene influences multiple phenotypic traits, which can contribute to complex polymorphic patterns, rather than gene interactions modifying trait expression (which is epistasis).
Epistasis is a mechanism where a single gene determines multiple polymorphic forms.
Answer: False
Epistasis refers to the interaction between different genes where one gene's expression modifies another's, contributing to complex trait expression, rather than a single gene determining multiple forms.
A 'switch' in polymorphism refers to the mechanism determining which morph an individual displays, which can be genetic or environmental.
Answer: True
The 'switch' in polymorphism refers to the underlying mechanism that determines which morph an individual expresses, and this mechanism can be either genetically determined or environmentally triggered (as in polyphenism).
What is a 'supergene' in the context of polymorphism?
Answer: A group of closely linked genes inherited together as a unit.
In the context of polymorphism, a 'supergene' refers to a group of closely linked genes inherited together as a unit, which collectively control complex polymorphic traits.
Which of the following best describes the role of pleiotropism in polymorphism?
Answer: A single gene influencing multiple traits can contribute to complex polymorphic patterns.
Pleiotropism, where a single gene affects multiple traits, can contribute to polymorphism by linking a visible polymorphic trait to other fitness-related or neutral characteristics.
How does epistasis relate to polymorphism?
Answer: It describes how one gene's expression is modified by another gene, contributing to complex patterns.
Epistasis relates to polymorphism by describing how interactions between different genes can modify trait expression, contributing to complex polymorphic patterns.
The jaguar's variation in coat color (spotted vs. melanistic) is an example of monomorphism.
Answer: False
The variation in coat color observed in jaguars, such as the presence of both spotted and melanistic morphs, is an example of polymorphism, not monomorphism.
Sexual dimorphism, where males and females differ in appearance, is considered a form of polymorphism.
Answer: True
Sexual dimorphism, characterized by distinct differences in appearance between males and females of a species, is recognized as a significant form of polymorphism.
Human blood types (like A, B, AB, O) are an example of cryptic polymorphism.
Answer: True
Human blood types (e.g., A, B, AB, O) serve as a classic example of cryptic polymorphism, where distinct forms exist but are not outwardly visible.
Female-limited polymorphism, seen in some butterflies, can sometimes serve to reduce harassment from males.
Answer: True
Female-limited polymorphism, observed in species such as certain butterflies, can serve adaptive functions, including potentially reducing harassment from males by mimicking less desirable forms.
Which of the following is cited as a common example of polymorphism?
Answer: The different coat colors (spotted and melanistic) found in jaguars.
The variation in coat colors, such as spotted and melanistic morphs, observed in jaguars is frequently cited as a common example of polymorphism.
Which of the following is an example of cryptic polymorphism?
Answer: Human blood types (A, B, AB, O).
Human blood types (A, B, AB, O) are an example of cryptic polymorphism, as these distinct forms are not outwardly visible but are identifiable through testing.
What is the proposed function of female-limited polymorphism in species like *Papilio dardanus*?
Answer: To mimic unpalatable species and avoid male harassment.
In species like the butterfly *Papilio dardanus*, female-limited polymorphism is proposed to function in mimicry of unpalatable species and potentially to reduce harassment from males.
Which of the following is an example of polymorphism in colonial organisms?
Answer: Specialized zooids (e.g., gastrozooids, gonozooids) within a single organism like *Obelia*.
The presence of specialized zooids (e.g., gastrozooids, gonozooids) within a single colonial organism, such as in *Obelia*, is an example of polymorphism in colonial organisms.
Polymorphism is ecologically significant because it enhances a species' ability to adapt to diverse or changing environments.
Answer: True
The ecological significance of polymorphism lies in its capacity to enhance a species' adaptability by maintaining a variety of forms that can better cope with diverse or fluctuating environmental conditions.
Polymorphism is thought to potentially decrease the rate of speciation by promoting genetic uniformity.
Answer: False
Polymorphism is generally considered to potentially increase, rather than decrease, the rate of speciation by facilitating adaptation to diverse niches and maintaining genetic variation within a population.
G. Evelyn Hutchinson proposed that most species consist of populations adapted to only a single niche, making polymorphism less relevant for niche exploitation.
Answer: False
G. Evelyn Hutchinson's work suggested that species are often adapted to multiple niches, and polymorphism plays a role in enabling species to exploit this niche diversity.
What is the ecological significance of polymorphism?
Answer: It helps populations cope with varied or changing environments by maintaining diverse forms.
The ecological significance of polymorphism lies in its ability to help populations adapt to varied or changing environments by maintaining a diversity of forms.
According to G. Evelyn Hutchinson, what is the likely relationship between species and ecological niches?
Answer: Polymorphism allows species to exploit multiple niches.
According to G. Evelyn Hutchinson's research, species often occupy multiple ecological niches, and polymorphism can facilitate the exploitation of this niche diversity.
What is the relationship between polymorphism and speciation?
Answer: Polymorphism is thought to be associated with a higher rate of speciation.
Polymorphism is hypothesized to correlate with an increased rate of speciation, as the presence of diverse forms can facilitate adaptation to different niches, potentially leading to reproductive isolation.
According to evolutionary theory, polymorphism is a heritable trait that is not subject to natural selection.
Answer: False
Evolutionary theory posits that polymorphism represents heritable variation and is subject to evolutionary forces, including natural selection, which can act to maintain or alter the frequencies of different morphs.
Research on polymorphism has historically supported the role of genetic drift over natural selection in shaping variation.
Answer: False
Historically, research on polymorphism, particularly in the mid-20th century, provided significant evidence supporting the role of natural selection as a primary driver of evolutionary change in natural populations, often in contrast to theories emphasizing genetic drift.
The study of polymorphism by E.B. Ford and colleagues was instrumental in establishing natural selection as a key driver of evolution in natural populations.
Answer: True
The research conducted by E.B. Ford and his colleagues on polymorphism was pivotal in reinforcing the understanding of natural selection as a significant evolutionary force acting within natural populations.
How does the study of polymorphism relate to the historical debate between natural selection and genetic drift?
Answer: It bolstered the argument for natural selection being a major driver of evolution in natural populations.
The study of polymorphism provided substantial evidence supporting natural selection as a key driver of evolution in natural populations, influencing the historical debate with theories emphasizing genetic drift.
How does Motō Kimura's neutral theory relate to the study of polymorphism?
Answer: It suggested that most molecular polymorphism is neutral, distinguishing it from phenotypic traits likely driven by selection.
Motõ Kimura's neutral theory posited that molecular polymorphism is largely driven by neutral drift, contrasting with phenotypic traits, which he considered more likely shaped by natural selection. Polymorphism studies often focus on the phenotypic level where selection is a primary factor.