Co-evolution, Lecture 8 Flashcards
Co-evolution
Occurs when selection pressures on one species are influenced by the evolution of another
Types of co-evolution
3
- inter-specific competition
- exploitation - predation
- mutualism
Inter-specific competition
Competition for resources between species
Character displacement
Differences among similar species, whose distributions overlap geographically, become accentuated.
Sympatry
Two species in the same space and same time
Allopatry
Two species are separate, in different spaces
Example of exploitation
Cuckoos, brood parasites
How are cuckoos brood parasites
lay eggs in the nests of other bird species
strong selection on host to reject cuckoo and strong selection on cuckoo to fool the host
How do female cuckoos fool the host so they can use their nests for their eggs?
female cuckoos specialise on one species,
reed warblers - reedbeds
dunnocks - farmland
meadouw pipits - moorland
Technique of female cuckoos when fooling host of nest
3
- very fast laying behaviour
- relatively thick shell to prevent removal by host
- lay eggs with colour and pattern to mimic host eggs
Adaptations of the cuckoo chick
hatches fast for size and removes host eggs/young from nest
Mutualisms
co-evolution through mutally positive association
Example of indirect co-evolution
insect aposematism
Insect aposematism
the use of bright colouration to advertise that an organism is danergous or unpalatable
‘warning colouration’
often poisenous
In what case can it be an advantage to stand out?
insect apposematism
