Evolution And Development Flashcards
Ontogeny
Development of individual organism
Haeckel rule
Developmental stages recapitulate evolutionary stages
von Baer law
No recapitulation of development with evolutionary stages
Embryos development increasingly diverse
Body’s consist of modules
Distinct units that have distinct genetic specifications, developmental patterns, locations, and interactions with other modules
Serially homologous modules
Modules that are repeated at various sites on the body
Individualization
Acquisition of distinct identities by modules
Fundamental principles
All cells have same set of genes
Differences in cells/tissue due to actions of different genes
Cell properties affect morphogenesis
Growth and development affected by chemical signals (hormones) and signaling molecules (morphogens)
Developmental cascades and gene regulatory networks
Homeotic mutation
Transforms one structure into another
Hox gene
Homeotic selector gene
Gene regulatory network making a fly
Polarity established by maternal effect genes
Proteins activate expression of gap genes - defines broad embryonic territories
These determine expression of pair-rule genes (fts) - specifies a region around 2 segments long
Activate segment polarity genes - divide each region into 2 segment-sized regions = each with anterior-posterior polarity
Segment polarity genes
Engrailed
Genetic toolkit
Genes shared widely among animals that can contribute to evolutionary changes in the regulation of diverse genes with diverse developmental roles
Phenotypic integration
Correlation between the state of two or more functionally related characteristics, so that they are advantageously matched in most individuals
Functionally interacting characters may be more evolvable
Modularity
Reduced pleiotropic integration enables independent evolvability
Developmental constraints
Lack of morphogenetic capacity
Strong correlations between traits due to pleiotropy
