198
G. W. Wah/farm
distribution
is
largely
a
result
of
competition
for food.
.
Asymmetry of size developes in a oarp population
shortly
after
the
beginning
of
active
feeding,
when
the
fish
are
grown
together in the same pond or
When
they
are
grown
individually
the
frequency
distribution
remains symmetrical.
This
asymmetry increases with increasing competition
for
food.
Removal
of
the
shoot
carp
is
followed by the production of
further
shoot carp by
the
truncated
Vice
versa
the
appearance
of
shoot
carp
may
be
largely
suppressed by the
addition
of
a
small
number
of
even
slightly
larger
individuals
(Wohlfarthr
The
asymmetry
of
carp’s
frequency
distribution
is thus
largely a result of
competition
for
food
between
individuals.
The
genetic
implications of this to the
selection
of
the
larger individuals and their
preferential
use
as
commercial
brood
stock
are
clear.
METHODS OF GENETIC
IMPROVEMENT
A
—
Mass
Selection
The
accepted
method
of
selection
in
Europe and Israel was
the
selection of
the
largest individuals, with the highest ratio
of
height
to
lengthn
The
response
to
selecting the largest
individuals was tested
in
a
bi—directional
selection
experiment
carried
out
during
five
consecutive
generations
(Moav
and
Nohlfarthf
This experiment involved Israeli mirror
carp,
which
are
largely of European extraction°
Comparison of the up
select
lines to their random control
showed
a
negative
response
during two generation followed by a positive response during tWD
subsequent
Both up select and their
control
lines
showed
a
slower
growth
than
that
of
a
standard crossbred
Down selection generated a response
during
the
first
three
generations,
equivalent
a
realized
heritability of 0-3:
but
thereafter the down
lines
ceased
to
respond
to
further
selection.
These
results were
obtained when
the
selection lineE
and
their controls were
tested
in
ponds.
When
samples
of
the
same
lines were
tested
in
cages,
up selection
showed
&
continued
response and
during the last three generations, growth of the up
select
lines
exceeded
that
of
the
crossbred
control.
The
applicative conclusion from this test is that selection
of
the
larger
individuals
is
not
an
effective method
for
improving
the
growth rate of carp grown in pondsn
The
response to
selection
for
body conformation was
tested
by
selecting
individuals
with
the highest and lowest ratio Of
height to length
(Ankorion,
Progenies
of
these
grDUP5
were
compared to progenies of a random
A clear respDn5€
to
selection was generated in both directions, equivalent
t°
a
realized heritability of 0.4°
G. W. Wah/farm
distribution
is
largely
a
result
of
competition
for food.
.
Asymmetry of size developes in a oarp population
shortly
after
the
beginning
of
active
feeding,
when
the
fish
are
grown
together in the same pond or
When
they
are
grown
individually
the
frequency
distribution
remains symmetrical.
This
asymmetry increases with increasing competition
for
food.
Removal
of
the
shoot
carp
is
followed by the production of
further
shoot carp by
the
truncated
Vice
versa
the
appearance
of
shoot
carp
may
be
largely
suppressed by the
addition
of
a
small
number
of
even
slightly
larger
individuals
(Wohlfarthr
The
asymmetry
of
carp’s
frequency
distribution
is thus
largely a result of
competition
for
food
between
individuals.
The
genetic
implications of this to the
selection
of
the
larger individuals and their
preferential
use
as
commercial
brood
stock
are
clear.
METHODS OF GENETIC
IMPROVEMENT
A
—
Mass
Selection
The
accepted
method
of
selection
in
Europe and Israel was
the
selection of
the
largest individuals, with the highest ratio
of
height
to
lengthn
The
response
to
selecting the largest
individuals was tested
in
a
bi—directional
selection
experiment
carried
out
during
five
consecutive
generations
(Moav
and
Nohlfarthf
This experiment involved Israeli mirror
carp,
which
are
largely of European extraction°
Comparison of the up
select
lines to their random control
showed
a
negative
response
during two generation followed by a positive response during tWD
subsequent
Both up select and their
control
lines
showed
a
slower
growth
than
that
of
a
standard crossbred
Down selection generated a response
during
the
first
three
generations,
equivalent
a
realized
heritability of 0-3:
but
thereafter the down
lines
ceased
to
respond
to
further
selection.
These
results were
obtained when
the
selection lineE
and
their controls were
tested
in
ponds.
When
samples
of
the
same
lines were
tested
in
cages,
up selection
showed
&
continued
response and
during the last three generations, growth of the up
select
lines
exceeded
that
of
the
crossbred
control.
The
applicative conclusion from this test is that selection
of
the
larger
individuals
is
not
an
effective method
for
improving
the
growth rate of carp grown in pondsn
The
response to
selection
for
body conformation was
tested
by
selecting
individuals
with
the highest and lowest ratio Of
height to length
(Ankorion,
Progenies
of
these
grDUP5
were
compared to progenies of a random
A clear respDn5€
to
selection was generated in both directions, equivalent
t°
a
realized heritability of 0.4°