DEVELOPMENT OF BEHAVIOR PART 2. Polyphenisms and Evo-Devo

Polyphenisms

provide additional examples of epigenetic effects occurring during development.

Different phenotypes can arise from developmental switch mechanisms that are triggered by different environmental influences, a process referred to as

phenotypic or developmental plasticity

Polyphenisms

a special type of phenotypic plasticity in which discrete phenotypes can arise from a single genotype

Polymorphisms

occur when discrete phenotypes with different genotypes are found in a population

Royal jelly

A queen is produced by feeding royal jelly to a developing bee. So all larvae have the potential to become a queen, but only the one fed royal jelly does so. Juvenile hormone from corpora allata has been shown to be involved in the queen- worker caste differentiation during the larval stage

Juvenile hormone

Besides its role in production of queens, __________ orchestrates the transitions that workers go through during their lifespan.

If a young bee is given juvenile hormone it becomes a

precocious forager

Predator-dependent polyphenism

kairomones

Fitness cost

lower reproduction (fewer eggs); less robut

Larvae were injected with different levels of 20E, producing a range of intermediate phenotypes not found in the wild. This is an experimentally elicited

reaction norm or norm of reaction

Not all genes are ________ that code for “building material” proteins.

structural genes

Many genes are ____________: genes that regulate the expression of one or more structural genes by controlling the production of a protein (such as a genetic repressor) which regulates the structural genes’ rate of transcription.

developmental regulatory genes

Hox genes (homeotic genes)

These are highly conserved genes .

Hox genes function to set segments of the insect (and other) bodies from head to tail

Hox genes are examples of general purpose control genes, laying out the basic body forms of many animals

Immediate early genes

Important in response of the genome to experiential effects

Foxp2

gene provides instructions for making a protein called forkhead box P2.

CREB

has a well-documented role in neuronal plasticity and formation of long-term memory

ZENK

increases rapidly in forebrain areas involved in vocal communication and possibly the formation of song-related memories

Relatively minor modifications in the timing and ordering of gene activity during embryonic life (_____) can produce enormous differences in adult phenotype

heterochrony

Neoteny

retention of juvenile features into adulthood. Adult humans resemble infant chimps, not adult chimps