SAT Reading - Khan Diagnostic Quiz level 3 - reading 21

Questions 1-11 are based on the following passage.

This passage is adapted from Anne-Laurence Bibost and Culum Brown, “Laterality Influences Schooling Position in Rainbowfish, Melanotaenia spp.” © 2013 by Brown, Bibost.

Many vertebrates and invertebrates show a preferential use
of one side of their body over the other, a phenomenon
known as laterality. Laterality stems from cerebral
Line lateralization, whereby specific types of information are
5 referentially processed in one hemisphere of the brain.
It is now widely accepted that brain lateralization conveys
both costs and benefits while performing certain tasks and
that it can have fitness consequences for animals in their
natural environment. Previous studies have demonstrated that
10 strongly lateralized animals perform better than non-
lateralized animals in a variety of contexts. For example,
Magat and Brown found that strongly lateralized parrots
were faster at learning a complex task than non-lateralized
parrots. In addition, strongly lateralized parrots and domestic
15 chickens were faster in discriminating between pebbles and
grains than non-lateralized individuals. Moreover, brain
lateralization is suggested to enhance simultaneous task
performance such as foraging whilst also looking out for
predators. The costs of laterality are various and context
20 specific. For example, strongly lateralized animals often have
difficulty in solving spatial tasks because their inherent turn
bias can be difficult to overcome. Similarly strongly
lateralized individuals perform relatively poorly when they
have to compare similar information in each visual hemifield.
25 The observed pattern of laterality across species, and
particularly the variation within species, is likely shaped by
natural selection to suit contemporary ecological and social
conditions. Large bodied parrots that use extractive foraging
techniques tend to be strongly lateralized whereas small
30 bodied species that graze on grass seeds and nectar are non-
lateralized. In addition, the pattern of lateralization varies
between populations subject to differential predation
pressure. Fish from high predation regions are more strongly
lateralized compared to fish from low predation regions and
35 their pattern of laterality also differs. It has been argued that
fish from high predation locations, or those that readily rely
on schooling, show enhanced laterality so that they can keep
track of their shoal mates and other stimuli simultaneously.
Laterality has been extensively studied using fish as model
40 organisms. A large number of fish species form schools (a
cohesive group of fish that swim in polarized
and synchronized manner) or shoals (a loose social aggregation
of fish). Group cohesion provides advantages by enhancing
foraging success and anti-predator behaviors.
45 It is easy to imagine how such finely tuned maneuvers
could be influenced by laterality. One might predict, for
example, that the stability and the cohesion of a fish school
are preserved if all the fishes tend to swim in the same
direction. Alternatively, perhaps schools are best comprised
50 of a range of lateralized individuals that prefer to take up
different locations within the school. It is possible that fish
with either a right eye or a left eye bias for viewing
conspecifics would be positioned on the left and right side of
the school respectively. This would allow lateralized fish to
55 simultaneously gather information about their school mates
in one hemifield and other key stimuli in the contra-lateral
hemifield (e.g., predators or prey).* In theory, this would
enable them to perform more efficient anti-predator or
foraging behavior due to their ability to process the
60 information more quickly in the appropriate hemisphere.
It is well documented that the position adopted by a fish
when swimming within a school is influenced by a range of
factors, including the internal motivational state (e.g., level
of hunger), hydrodynamics and predator avoidance strategies.
65 Moreover, positions within a school have different costs and
benefits associated with them. For example, peripheral
positions may enhance foraging opportunities, but they are
also more vulnerable to predation. Individuals within
populations vary in their laterality scores and the present
70 study suggests that each fish positions itself within the school
accordingly. Individuals that were more left lateralized when
viewing their mirror image were found in positions at the
periphery of the school keeping the majority of their shoal
mates within their preferred visual field. It is highly likely
75 that this school position is the product of an active choice on
the behalf of the fish which compete for their preferred
positions within the school in a highly dynamic fashion and
is dependent on the laterality scores of the other fish in the
school. It may be that strongly lateralized fish (particularly
80 right biased individuals) benefit from occupying in these
positions but we have yet to conduct tests which involve
predator or prey detection in a schooling context.

*A hemifield is one half of a visual field; "contra-lateral" means pertaining to the other side.

 
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