Lecture 15 - Evo-Devo Flashcards
What does “Evo-Devo” stand for?
Evolutionary developmental biology, studying how genetic and environmental processes drive phenotype development and how these influence evolution.
How does Evo-Devo connect development and evolution?
It links development (genotype to phenotype) and evolution (selection acting on phenotypes to alter genotypes over time).
Define “cis-acting elements” in gene regulation.
DNA regions close to a gene, such as enhancers and promoters, that regulate the gene’s expression.
What are “trans-acting elements” in gene regulation?
Proteins, such as transcription factors, that bind to DNA at distant locations to regulate gene expression.
Proteins, such as transcription factors, that bind to DNA at distant locations to regulate gene expression.
Enhances transcription factor binding stability, creating sharp boundaries of gene expression, crucial for development.
What is the importance of signalling pathways in development?
They enable communication between cells, influencing gene expression and guiding tissue and organ formation.
What are maternal-effect genes?
Genes whose mRNA or proteins are deposited in the egg by the mother, influencing early embryonic development.
Describe the anterior-posterior axis development in Drosophila.
Maternal-effect genes set gradients (e.g., bicoid protein) that guide the spatial expression of segmentation genes.
What are “pair rule genes” and “segment polarity genes”?
Pair rule genes: Define repeated embryonic stripes.
Segment polarity genes: Refine boundaries and pattern within each segment.
How do homeotic (Hox) genes influence body development?
They assign identity to body segments, with their spatial arrangement corresponding to their chromosomal order.
What is the “genetic toolkit” of development?
A set of conserved genes that regulate body patterning, formation, and primary axes in various organisms.
Why are regulatory mutations key for evolution?
They can alter gene expression in specific tissues or times without disrupting overall protein function, offering adaptability.
What is the evolutionary significance of “cis-element evolution”?
It allows tissue-specific or time-specific gene expression changes, influencing traits without altering the protein.
What developmental adaptation is seen in Stickleback fish?
Loss of pelvic spines in shallow water populations due to mutations suppressing pelvic enhancer activity.
How does trans-regulation evolve?
By adding new binding motifs to transcription factors, enabling them to interact with new DNA targets or proteins.
What are developmental constraints?
Limits to evolution caused by genetic correlations or essential developmental pathways.
Give an example of developmental plasticity.
Aquatic plants producing aerial and submerged leaf types in response to environmental conditions.
What role do enhancers play in gene regulation during development?
Enhancers act as binding sites for transcription factors, influencing where, when, and how much a gene is expressed.
How are multiple cis-elements used for cooperative gene regulation?
Multiple identical cis-elements can bind transcription factors, and cooperative binding ensures rapid and robust activation of gene expression.
What is the difference between maternal-effect genes and zygotic genes in development?
Maternal-effect genes are deposited in the egg by the mother and guide early development, while zygotic genes are expressed by the embryo itself.
Why are chiasmata essential in meiosis?
Chiasmata, resulting from crossovers, ensure proper segregation of homologous chromosomes by holding them together until separation.
Chiasmata, resulting from crossovers, ensure proper segregation of homologous chromosomes by holding them together until separation.
The bicoid gradient provides positional information along the anterior-posterior axis, guiding the expression of gap and pair-rule genes.
How do gap genes contribute to development?
Gap genes are expressed in broad regions of the embryo and establish the primary body plan by regulating pair-rule and segment polarity genes.
What is the role of Hox genes in segment identity?
Hox genes specify the identity of segments by controlling the expression of downstream genes that shape morphology.
Explain the concept of “positional information” in development.
Positional information refers to spatial cues, like morphogen gradients, that determine the location-specific activation of genes during development.
How do mutations in cis-regulatory elements drive evolution?
Cis-element mutations can change gene expression patterns without affecting protein function, enabling morphological diversification.
How does trans-element evolution differ from cis-element evolution?
Trans-element evolution involves changes in transcription factors, such as their binding abilities or interaction with other proteins, leading to novel functions.
What is the significance of conservation in the genetic toolkit?
Conserved genes like Hox clusters indicate their critical roles in development and evolution, as their functions have been maintained across diverse species.
What is the role of signalling components like Hedgehog in development?
Hedgehog acts as a morphogen, creating gradients that regulate tissue patterning and segment formation.
How do enhancer mutations affect pigmentation in Drosophila species?
Mutations in wing enhancers of the yellow gene increase transcription factor binding, leading to higher expression and darker pigmentation.
How do segment polarity genes refine the body plan?
Segment polarity genes define and stabilize segment boundaries, ensuring proper organization of the body.
What is the evolutionary importance of gene duplication?
Gene duplication provides raw material for evolution, allowing one copy to maintain its function while the other can acquire new roles.
How does environmental plasticity impact development?
Environmental cues can alter phenotypic expression, enabling organisms to adapt to varying conditions without genetic changes.
What is the connection between gene dosage and chromosomal segregation?
Imbalances in gene dosage due to incorrect segregation can disrupt cellular function and lead to developmental disorders.
What developmental constraints limit “evolvability”?
Limited genetic variation, strong correlations between traits, and pleiotropic effects restrict the potential for evolutionary changes.
What is the “context dependency” of the genetic toolkit?
Genes in the toolkit are reused in different developmental processes, with their function depending on the specific tissue or time of expression.
What is the significance of “modular” changes in cis-elements?
Modular changes allow gene expression to be altered in specific tissues or times, minimizing negative impacts on overall fitness.
