MBIO161 Genetics 7-12

What defines Mendelian inheritance?

Mendelian inheritance refers to the inheritance patterns of discrete genetic characters that show a limited number of distinct categories.

What is a phenotype?

A phenotype is the outward, physical appearance of a trait.

What is a character in genetics?

A character is a heritable feature, such as flower color.

What is a trait?

A trait is a variant of a character, such as purple or white flowers.

What does genotype refer to?

Genotype is the coded, inheritable information in an organism’s DNA.

What is an allele?

An allele is one specific form of a gene that differs from other alleles by one or a few bases and occupies the same locus.

What is the difference between homozygous and heterozygous alleles?

Homozygous alleles are both the same (AA or aa), while heterozygous alleles are different (Aa).

What is Mendel's Law of Segregation?

Mendel's Law of Segregation states that the two alleles at any one locus in a diploid individual separate during gamete formation.

What is a monohybrid cross?

A monohybrid cross involves one character only and typically results in a 3:1 phenotypic ratio.

What is a dihybrid cross?

A dihybrid cross involves two characters and typically results in a 9:3:3:1 phenotypic ratio.

What does Mendel's Law of Independent Assortment state?

This law states that each pair of alleles at any one locus segregates independently of other pairs of alleles at other loci.

Can dominant alleles always be expected to be more common than recessive alleles?

No, dominant alleles are not always more common than recessive ones.

What did Hardy and Weinberg demonstrate?

They demonstrated that allele frequencies will stay constant under certain conditions in a population.

What assumptions does the Hardy-Weinberg model make?

Infinite population size, random mating, no mutations, no selection, and equal allele frequencies among sexes.

What is genetic linkage?

Genetic linkage occurs when alleles at separate loci are inherited together and do not obey Mendel's law of independent assortment.

What is the impact of cytoplasmic inheritance?

Cytoplasmic inheritance involves traits inherited from organellar DNA.

What are polygenic characters?

Polygenic characters are individual heritable traits controlled by several genes, leading to continuous variation.

What is phenotypic plasticity?

Phenotypic plasticity is when a genotype expresses different phenotypes depending on the environment.

What is heritability in genetics?

Heritability is the proportion of phenotypic variation due to genetic variation.

How do fitness and natural selection relate?

Natural selection operates on heritable traits that show variation in fitness.

What is artificial selection?

Artificial selection is the human-directed breeding of organisms to enhance desired traits.

What is the Red Queen hypothesis?

The Red Queen hypothesis suggests that organisms must constantly evolve to keep up with changing environments and competing organisms.

What is intrasexual selection?

Intrasexual selection is when members of the same sex compete for access to mates.

What is the handicap principle in sexual selection?

The handicap principle states that reliable signals must be costly to the signaller, indicating high genetic quality.

What is the Fisherian runaway?

The Fisherian runaway suggests that female preference for male traits can lead to exaggerated traits over generations.

What is a lek?

A lek is an assembly area where males display to attract females.

What does genetic drift refer to?

Genetic drift is the change in allele frequencies due to random sampling effects in small populations.

What is the role of environmental factors in natural selection?

Environmental factors influence relative fitness and can drive Darwin's theory of natural selection.

What is the two-fold cost of sexual reproduction?

Sexual females have half as many daughters as asexual females, leading to a slower population growth rate.

What are co-evolutionary arms races?

Co-evolutionary arms races occur between hosts and parasites as they adapt against each other's defenses.

What is the significance of mating strategies in sexual selection?

Mating strategies influence reproductive success and the evolution of traits in both males and females.

How do genes and the environment interact?

The interaction between genetics and the environment leads to phenotypic variation.

What does the term 'standing genetic variation' refer to?

Standing genetic variation refers to the presence of alternative forms of a gene in a population.

What is the role of sexual dimorphism?

Sexual dimorphism refers to differences in appearance, often related to reproductive strategies, between males and females.

What does the term 'lethal gene' mean?

A lethal gene is an allele combination that leads to the death of an individual.

What are sex-linked traits?

Sex-linked traits are associated with genes located on sex chromosomes, often exhibiting different patterns in males and females.

What is the difference between fitness and heritability?

Fitness measures reproductive success, while heritability indicates how much of phenotypic variation is due to genetics.

What is directional selection?

Directional selection favors one extreme phenotype over others in a population.

What is stabilizing selection?

Stabilizing selection favors average traits and selects against extreme traits.

What is disruptive selection?

Disruptive selection favors extreme traits at both ends of the spectrum over intermediate traits.

What is the concept of meiotic drive?

Meiotic drive is a process that causes some genetic variants to be over-represented in gametes during meiosis.

What is a segregating locus?

A segregating locus is a specific location on a chromosome where two or more alleles are present in a population.

How does sexual reproduction impact genetic diversity?

Sexual reproduction increases genetic diversity through independent assortment and recombination during gamete formation.

What is genetic cleanliness hypothesis?

The genetic cleanliness hypothesis suggests that individuals with fewer mutations have a selective advantage.

What is the relationship between genotypes and phenotypes?

Different genotypes can produce the same phenotype due to environmental influences.

What is the role of the environment in phenotypic variation?

The environment interacts with genetics to produce variation in phenotypes.

What does the term 'quantitative inheritance' signify?

Quantitative inheritance refers to traits controlled by multiple genes contributing to continuous variation.

What is the significance of the Hardy-Weinberg equilibrium?

The Hardy-Weinberg equilibrium provides a null model to test if evolution is occurring in a population.

What is the importance of gene flow in evolution?

Gene flow allows for the exchange of genetic material between populations, affecting genetic diversity.

What are B chromosomes?

B chromosomes are additional chromosomes that can be transmitted more frequently than expected through Mendelian inheritance.

How does natural selection lead to adaptations?

Natural selection favors traits that enhance survival and reproductive success in specific environments.

What are codominant alleles?

Codominant alleles express both phenotypes in the heterozygote, as seen in red/white spotted cows.

What is the significance of Hardy-Weinberg expectations?

They provide predictive frequencies for allele distributions in a population under certain conditions.

What are the implications of polygenic traits?

Polygenic traits show continuous variation and are influenced by multiple genes.

What is sexual selection?

Sexual selection is the process by which certain traits increase mating success, often leading to elaborate features.

What does the term 'asexual reproduction' refer to?

Asexual reproduction is a mode of reproduction that does not involve the fusion of gametes.

What is parthenogenesis?

Parthenogenesis is a form of asexual reproduction where offspring develop from unfertilized eggs.

What are the costs associated with sexual reproduction?

Costs may include time and energy spent in finding mates and producing gametes.

What is genetic variability and why is it important?

Genetic variability allows populations to adapt to changing environments and is crucial for evolutionary processes.

How do mate choices affect reproductive success?

Mate choices influence genetic quality and the traits passed to the offspring, impacting overall fitness.

What are the consequences of genetic bottlenecks?

Genetic bottlenecks can significantly reduce genetic diversity in small populations.

What is the concept of sexual dimorphism in evolutionary biology?

Sexual dimorphism refers to differences in form and behavior between males and females of the same species.

What role do sexual ornaments play?

Sexual ornaments signal genetic quality, fitness, and disease resistance to potential mates.

What is the role of the ZW sex determination system?

In the ZW system, females are ZW, and males are ZZ, commonly seen in birds.

What are the types of selection that can occur in nature?

The types are directional, stabilizing, and disruptive.

What is the lek paradox?

The lek paradox suggests that despite strong sexual selection favoring certain male traits, the traits do not diminish in variation due to genetic factors like sexually-selected benefits.

What are the different types of selection in evolution?

The main types of selection are directional selection, stabilizing selection, disruptive selection, and sexual selection, each impacting populations in various ways.

What is parental investment theory?

Parental investment theory posits that the energy and resources invested by parents into raising offspring influence mating behaviors and reproductive strategies.

What is the difference between intrasexual and intersexual selection?

Intrasexual selection involves competition among members of the same sex for mates, while intersexual selection entails preferences by one sex for the traits of the opposite sex.

What is convergence in evolution?

Convergence is when unrelated species evolve similar traits due to similar environmental pressures.

What is adaptive radiation?

Adaptive radiation is the rapid diversification of a species into a variety of forms that adapt to different environments.

What is phyletic gradualism?

Phyletic gradualism is the hypothesis that evolution occurs gradually over long periods.

What is punctuated equilibrium?

Punctuated equilibrium suggests that species remain stable for long periods, interrupted by brief, rapid changes in response to environmental shifts.

What is the role of sexual selection in evolution?

Sexual selection encourages traits that improve mating success, impacting species evolution and diversity.

What is balancing selection?

Balancing selection occurs when multiple alleles are actively maintained in a population due to selective pressures.

What is frequency-dependent selection?

Frequency-dependent selection is when the fitness of a phenotype depends on its frequency relative to other phenotypes in a population.

What is isogamy?

Isogamy is the fusion of two gametes that are identical in morphology, typically seen in some algae and fungi.

How does isogamy differ from anisogamy?

Isogamy involves gametes of equal size, while anisogamy involves gametes of different sizes (usually small sperm and larger eggs).

What are the reproductive implications of isogamy?

Isogamy can promote genetic diversity without the need for distinct male and female gametes.

What is the primary difference between sexual and asexual reproduction?

The primary difference is that sexual reproduction involves the fusion of gametes from two parents, while asexual reproduction does not involve gametes and results in offspring genetically identical to the parent.

What are some advantages of sexual reproduction?

Advantages of sexual reproduction include increased genetic diversity, adaptability to changing environments, and potential for enhanced survival of species.

What are some advantages of asexual reproduction?

Advantages of asexual reproduction include faster population growth, the ability to reproduce without a mate, and immediate colonization of favorable environments.

What are common forms of asexual reproduction?

Common forms of asexual reproduction include binary fission, budding, fragmentation, and vegetative propagation.

How does sexual reproduction contribute to evolutionary processes?

Sexual reproduction contributes to evolutionary processes by generating genetic variation, which is crucial for adaptation and natural selection.

What is the impact of asexual reproduction on genetic variability?

Asexual reproduction typically results in lower genetic variability compared to sexual reproduction, as offspring are clones of the parent.

What is an example of an organism that reproduces asexually?

An example of an organism that reproduces asexually is a bacterium, which can divide by binary fission.

What is an example of asexual reproduction in plants?

An example of asexual reproduction in plants is through runners, where new plants grow along the soil surface from the parent plant.

What is the Red Queen hypothesis?

The Red Queen hypothesis suggests that organisms must constantly evolve to survive against ever-evolving opposing organisms.

What are polygenic characters?

Polygenic characters are traits controlled by multiple genes, leading to a range of phenotypes.

What does quantitative inheritance refer to?

Quantitative inheritance refers to traits that show continuous variation and are influenced by several genes.

What are continuous characters?

Continuous characters are traits that can take on a range of values, such as height or skin color.

What is phenotypic plasticity?

Phenotypic plasticity is the ability of a single genotype to produce different phenotypes in response to varying environmental conditions.

What is meiotic drive?

Meiotic drive is a phenomenon where certain alleles are passed on to offspring at higher rates than their counterparts during meiosis.

What is genetic linkage?

Genetic linkage occurs when genes located close together on a chromosome are inherited together more often than not.

What are lethal genes?

Lethal genes are alleles that result in the death of an organism when present in certain combinations.

What is the difference between codominance and incomplete dominance?

Codominance occurs when both alleles in a heterozygote are fully expressed, while incomplete dominance results in a blended phenotype.

What is broad sense heritability?

Broad sense heritability is the proportion of phenotypic variance in a population that is attributable to genetic variance.

What is genetic drift?

Genetic drift is the change in allele frequencies in a population due to random sampling effects, particularly in small populations.

What are bottleneck events?

Bottleneck events occur when a population's size is significantly reduced, leading to a loss of genetic diversity.

What are founder events?

Founder events occur when a new population is established by a small number of individuals, leading to reduced genetic variation.