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Flashcards in Evo Devo Deck (15):

Ernst Haeckel

tied similarities between various animal embryos and development pathways critical to establishing homology to evolutionary change


Ontogeny recapitulates phylogeny

single celled zygote --> jelly fish like gastrula --> wormlike embryo --> fish like embryo --> tadpole like embryo --> tetrapod fetus


Master gene

Genes that control where, when, and how other genes are expressed

-make proteins that signal, activate, mark, or otherwise communicate with other genes and their products

- often sequentially expressed in a set pattern

- also called homeotic(HOX) or developmental regulatory genes


Homeotic Genes

genes regulate where, when, and how genes downstream will be expressed

expression of body parts --> "antennapedia" is the most famous

highly conserved and often occurring in a multi-gene families (result of ancestral duplications?)


HOX gene expression

set up anterior/posterior and dorsal/ventral in insects

anterior is the front towards the head, posterior is the back towards the butt

dorsal is the top side and ventral is the bottom side


Gene duplication

most important source of new genes

misalignment in meiosis leads to unequal crossing over (one chromosome gets extra copies of a gene)


consequences gene duplication

"new" copy may not have same functional constraints as ancestral copy

mutations may accumulate in new copy with fewer consequences

mutations may allow daughter to perform new functions

may help or hurt...


Gene families

cluster of genes similar in structure and sequence

ex. HOX genes


Globin Genes

example of a gene family

similar in structure --> repeated sequence motifs that allow us to recognize them as similar

different genes expressed at different times in development --> genes can be "turned on/off"

each gene product is slightly different (ex. fetal product has higher affinity for oxygen)

selection acts independently on each gene


Complex change

Can come from very simple basis


Conservation of HOX genes

anterior-posterior axis

co-linear on chromosomes


what do master genes also specify?

master genes also specify similar kinds of structures

eye development spurred by PAX genes --> even though eyes form differently, all initiated by similar genes


difference between evolutionary theory and evo-devo

classical evolutionary theory looks at survival of the fittest

evo-devo looks at the ARRIVAL of the fittest


what is polyploidy?

more copies of ALL genes


what are pseudogenes?

non-functional genes that are still included in a gene family

usually not transcribed

may eventually evolve new function or role through changes in sequence or in transcription pattern