Biology Reference
In-Depth Information
Both the host and the parasite produce
resting stages that accumulate in lake
sediments, providing a living 'fossil record'
of past generations. Host and parasite
populations from different generations (over
a 39-year period) were restored by
reactivating dormant host eggs and parasite
spores.
Daphnia
were then exposed to
parasites from the same sediment layer
(contemporary parasites) and from sediment
layers with past and future parasite
populations. Infectivity was higher with
contemporary parasites than with parasites
from previous growing seasons; therefore,
the
Daphnia
evolved to beat past parasite
genotypes while the parasites, in turn,
rapidly evolved to adapt to the changing host genotypes. Infectivity was also lower with
parasites from future growing seasons; therefore, parasite adaptations were specific to
PREDATORS
selection for improvements
in foraging
PREY
selection for improvements
in defences
Fig. 4.1
Selection for efficient
foraging by predators selects for
better prey defences, which in turn
selects for predator improvements,
further prey improvements and
so on.
Predator activity
Predator adaptations
Counter-adaptations by
prey
Table 4.1
Examples of
predator
adaptations and
counter-
adaptations by
prey.
Searching for prey
Improved visual acuity
Crypsis (background
matching, disruptive
patterns, countershading)
Polymorphism
Space out
Search image
Search limited area where
prey abundant
Recognition of prey
Learning
Masquerade (resemble
inedible object)
Warning signals of toxicity
(aposematism, Müllerian
mimicry)
Deceive predators by
mimicking defended prey
(Batesian mimicry)
Catching prey
Secretive approach, motor
skills (speed, agility)
Signal to predator that
it's been detected
Escape flight
Startle response:
eyespots
Deflect attack
Weapons of defence
Weapons of offence
Handling prey
Subduing skills
Active defence, spines,
tough integuments
Toxins
Detoxification ability
