Birds Flashcards
What determines differences in bird colouration and ornamentation.
Habitat
evolution
sexual selection
*Habitat constraints
–light conditions
-nesting site – hole, open etc
-food type
-predation level
*Evolutionary history
*Degree of female choice choosing for good home or genes
-Level of male competition
What factors make male and female birds more colourful
More rain, food/nector, forest and community diversity
What happens to migratory female birds
They become less colourful
Reasons for competition of sexual selection
1) competition within one sex for access to mates or
2) because one sex prefers to receive mate with certain members of the opposite sex
1) Intra sexual competition – usually males fighting
2) Inter sexual competition – usually females choosing
Natural Selection description
Natural selection: leads to evolutionary change when individuals with certain characteristics have a greater survival rate than other individuals in a population and pass on these inheritable genetic characteristics to their offspring
2nd Darwin ideal of sexual selection
Sexual Selection: The advantage which certain individuals have over others of the same sex and species in exclusive relation to reproduction
Colour in feathers
keratin in the feathers decides the colours
colours indicate different things;
Red, Orange, Yellow Plumage
Produced using carotenoids
Can only be obtained from the diet
Also used in immune response (linked to vitamin A)
Yellow = unmodified, red = modified
there are exceptions
Where does the colour red come from in In Parrots, Macaws, Lorikeets and Cockatoos:
In Parrots, Macaws, Lorikeets and Cockatoos:
Red, Pink, Orange, and Yellow colour comes from – psittacofulvins
Not from diet like carotenoids- synthesised at site of developing feathers
Unique in nature and some also fluoresce under UV light
Turacos and its green and red colour
Turaco wings contain the red pigment Turacin
Turacoverdin is a unique copper
The uroporphyrin pigment is responsible for the bright green (chemically related to turacin) and is the only true green pigment
Both linked to diet rich in fruits which provide copper
Black and brown colours in birds
hormones affect:
pattern
size
Melanin based colouration
Blacks, browns, some reds (also a few greens and yellows)
produced using amino acids
size of patch controlled by genes
hormones affect:
pattern – thyroxine
size – testosterone
Some effect of diet
Carotenoids
Tetraterpenes
Lipid soluble
Brightly coloured
β carotene = Vitamin A
Derived from plants but can be modified
Ketolase adds a carbonyl
Psittacofulvins
Unsaturated polyenes – many double bonds
Reduced form of a C18:8 fatty acid
Unusual spectroscopic properties due to arrangement
Lipid soluble
Porphyrin pigments
Porphyrin ring with four coordinating nitrogens
Can coordinate metal ions e.g. haem group in haemoglobin
Colour dependent on oxidation state of metal (oxygenated vs deoxygenated blood)
Melanin
Insoluble polymer derived from the amino acids phenylalanine and tyrosine
Eumelanin (black)
Phaeomelanin (brown/ginger) – needs cysteine
Structural stability and colour - wing tips
