Speciation and Melanin Production

Evolution of the MC1R gene

MC1R gene MC1R = cell membrane receptor, 317 aa long Binds to melanin stimulating hormone. This binding causes

change in MC1R protein that makes tyrosinase that then makes black melanin (eumelanin).

Lack of MSH does not produce tyrosinase and then only pheomelanin (yellow/red) is produced.

Albinism mutation: Mutation in gene coding for tyrosinase. Chromosome

11. No melanin (red or black) can be produced.

Soloman Flycatchers

Chestnut-bellied flycatcher (Makira Island)

Black-bellied flycatcher (Santa Ana Island)

Sexual Selection

In humans:

Redhead gene a mutation: Chromosome 16, amino acid #151 changed from argenine to cysteine Redheads only produce the red/brown type of melanin (pheomelanin)

G-Protein coupled Receptors (GPCR) – inherited proteins

G- Protein Coupled Receptors

GPCR = largest family of proteinsFound in all 3 domainsOf 30,000 human genes, 1000 are GCPR

5% of mammal DNA are GCPR for odorPrimates have only 300 odor receptors- (others have mutation with stop codon within them)

Vision receptors are CGPR

Taste is a GPCR too!