Behaviour and Adaptation!
Behaviour and adaptation: examples
Behavioural adaptation often looks simple although the details could reveal complex
patterns
Adaptations often look deceptively simple although to reveal the full explanation one
needs to combine experiments with field observations and phylogenetic analyses
1. Simple example: hunting by cheetah
Impala is one of the main prey items of cheetah
The cheetah relies on speed to catch impalas: they can reach up to 100 km/h
The top speed of impala about 60 km/h
Cheetah can only sustain top speed for a short burst
Only about 10% of cheetah hunts are successful
Selection should favour high speed in BOTH cheetah and impala
Predictions:
Fastest cheetah should have the highest fitness
Slowest impala should have the lowest fitness
These predictions can be tested using simple tools
Why we may NOT find these results…
No variation in traits (ie running speed)
Running speed is variable BUT has no heritable component
Speed may not be main component of hunting success – stealth and manoeuvrability whilst chasing
the prey
There are trade-offs, eg fastest cheetah are more vulnerable to predators and parasites
2. Complex example: colonial behaviour of gulls
Many birds breed in colonies
Large numbers can breed in a single colony (up to 1 million birds)
Colonies can reach high densities (up to 40 nests/m2)
WHY breed in colonies?
H1: protection from predators
H2: increased foraging success
Black-headed gulls protect the colony:
-- Nests inside the colony are protected more intensely than nests outside the colony
-- Nest protection is more successful inside than outside the colony
Colonies may attract predators and some colonies are more vulnerable to predators than others
Prediction: exposure to predators influences egg camouflage, and the behaviour of adults and chicks
, SUMMARY: adaptation to predation by colonial birds =>
X Limitations: 2 species only, not quantitative, phylogenetic inertia (or
phylogenetic constraint. Refers to the limitations on the future
evolutionary pathways that have been imposed by previous adaptations)
Phylogenetic reconstruction of
coloniality in gulls:
-- cliff-nesting evolved once
-- if a trait (like coloniality) evolved
multiple times, the trait can be
analysed statistically
Behaviour and adaptation: difficult cases
Behaviour of animals still provides numerous unresolved questions
1. Penis fencing in flatworms
Flatworms are hermaphrodites, with penises which act like hypodermic needles. They
engage in battles to establish who is the father and the mother in a partnership. Successful
Behaviour and adaptation: examples
Behavioural adaptation often looks simple although the details could reveal complex
patterns
Adaptations often look deceptively simple although to reveal the full explanation one
needs to combine experiments with field observations and phylogenetic analyses
1. Simple example: hunting by cheetah
Impala is one of the main prey items of cheetah
The cheetah relies on speed to catch impalas: they can reach up to 100 km/h
The top speed of impala about 60 km/h
Cheetah can only sustain top speed for a short burst
Only about 10% of cheetah hunts are successful
Selection should favour high speed in BOTH cheetah and impala
Predictions:
Fastest cheetah should have the highest fitness
Slowest impala should have the lowest fitness
These predictions can be tested using simple tools
Why we may NOT find these results…
No variation in traits (ie running speed)
Running speed is variable BUT has no heritable component
Speed may not be main component of hunting success – stealth and manoeuvrability whilst chasing
the prey
There are trade-offs, eg fastest cheetah are more vulnerable to predators and parasites
2. Complex example: colonial behaviour of gulls
Many birds breed in colonies
Large numbers can breed in a single colony (up to 1 million birds)
Colonies can reach high densities (up to 40 nests/m2)
WHY breed in colonies?
H1: protection from predators
H2: increased foraging success
Black-headed gulls protect the colony:
-- Nests inside the colony are protected more intensely than nests outside the colony
-- Nest protection is more successful inside than outside the colony
Colonies may attract predators and some colonies are more vulnerable to predators than others
Prediction: exposure to predators influences egg camouflage, and the behaviour of adults and chicks
, SUMMARY: adaptation to predation by colonial birds =>
X Limitations: 2 species only, not quantitative, phylogenetic inertia (or
phylogenetic constraint. Refers to the limitations on the future
evolutionary pathways that have been imposed by previous adaptations)
Phylogenetic reconstruction of
coloniality in gulls:
-- cliff-nesting evolved once
-- if a trait (like coloniality) evolved
multiple times, the trait can be
analysed statistically
Behaviour and adaptation: difficult cases
Behaviour of animals still provides numerous unresolved questions
1. Penis fencing in flatworms
Flatworms are hermaphrodites, with penises which act like hypodermic needles. They
engage in battles to establish who is the father and the mother in a partnership. Successful
