Bidirectional mass selection for body shape in common carp

HAL Id: hal-00893943

https://hal.archives-ouvertes.fr/hal-00893943

Submitted on 1 Jan 1992

HAL is a multi-disciplinary open access

archive for the deposit and dissemination of

sci-entific research documents, whether they are

pub-lished or not. The documents may come from

teaching and research institutions in France or

abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est

destinée au dépôt et à la diffusion de documents

scientifiques de niveau recherche, publiés ou non,

émanant des établissements d’enseignement et de

recherche français ou étrangers, des laboratoires

publics ou privés.

Bidirectional mass selection for body shape in common

carp

Y Ankorion, R Moav, Gw Wohlfarth

To cite this version:

Original

article

Bidirectional

mass

selection

for

_{body shape}

in

common

_carp

Y

_Ankorion,

R Moav

GW

Wohlfarth

Agricultural

Research _{Organization,} Fish and _Aquaculture Research _Station, Dor, DN _Hof Hacarnael _30820, Israel

(Received

27 November _{1990; accepted} 19 November

₁₉₉₁₎

Summary - Bidirectional mass selection for the ratio of

height/length

generated a

response in both directions. Estimates of realized heritability were 0.47 f 0.06 and

0.33 ±0.10 for up and down selection respectively and 0.42 t 0.03 for the divergence. This

means that _{body shape} of common _carp can be _{changed fairly rapidly by} mass selection. Presumably, differences in _{body shape among} different genetic groups of common carp

are due to different intensities and number of _generations of mass selection for this trait practised in the _past. The traditional belief that _{body shape} and _growth rate are correlated was not confirmed in this _study. The down selection _{line, possessing} the lowest ratio of

_{height/length,}

showed the fastest _growth rate. At face value this _implies a _negative

correlated response of growth to selection for

_{height/length.}

We suggest treating this finding with some _reservation, since growth did not differ _{significantly} among our test

lines. These results _may be _applied to _{aquaculture by selecting} for an _increasing ratio of

height/length

only if _high backed fish have some _advantage in their own _right such as a

higher

price or _improved market _acceptance.

common carp / body shape / realized _{heritability /} bidirectional mass selection

Résumé - Sélection massale _divergente pour la conformation chez la carpe commune.

Une sélection massale _{divergente pour} la _conformation chez la carpe commune

_(rapport

hauteur/longueur)

a _produit une _réponse à la

_fois

vers le haut et vers le bas. Les

estimées de l’héritabilité réalisée _après une _génération de sélection sont _{0,47 :i: 0, 06} et

0,33 !: 0,10 respectivement dans la _lignée haute et dans la _{lignée basse,} et _{0,42 :i: 0,03} pour la divengence entre les 2 _lignées. Cela _suggère que la conformation de la carpe

commune _peut être _modifiée assez rapidement _par sélection massale. Il est _probable que les

différences de _conformation entre _{différents groupes}

_génétiques

de carpe sont le résultat

d’une sélection pour ce _{caractère, effectuée} avec des intensités et sur un nombre de générations variables selon les groupes. Cette étude ne confirme _pas l’opinion courante

selon _laquelle la _conformation et la vitesse de croissance sont corrélées : c’est en _effet la

T _Deceased

*

lignée basse, possédant le _rapport

_{hauteur/longueur}

le _{plus faible, qui manifeste} la plus forte croissance. Ce _{résultat, qui impliquerait} une corrélation _négative entre croissance

et _{conformation,} doit _cependant être _interprété avec _réserve, les _différences de croissance

entre les lignées expérimentales n’étant pas significatives. Compte tenu de ces résultats une

sélection pour un _rapport

hauteur/longueur

accru se _justifie en _aquaculture à condition _que

les _poissons à conformation « ramassée» aient un _{avantage intrinsèque,} tel _que un meilleur

prix de vente ou une meilleure acceptabilité.

carpe commune / conformation / héritabilité réalisée _/ sélection _divergente

INTRODUCTION

In the traditional _carp culture _management in central and eastern

_{Europe, body}

shape

and

_particularly

the ratio of

_{height/length}

is

_regarded

as

_important.

This

trait

_responds

to environmental influences

_(Anwand,

_1961;

_Mann,

₁₉₆₁₎

and

distinguishing

carp races

_by

their

_{body shape}

is considered unreliable.

Nevertheless,

among common

_European

_{carp races,}

Aischgrund

and Galician are

_regarded

as

relatively high backed,

and Lausitz and Frankish as

having

a

relatively elongated

body shape (Willer,

1933; Hofmann,

1975).

The traditional method of

_selecting

brood stock at the time of

_harvesting

_3-year

old fish consisted of

_picking

out the

largest

individuals with the

_highest

ratio of

_{height/length (Hofmann, 1975).}

This

practice

was based on the belief that the ratio of

_{height/length}

is correlated to

growth,

and that both

_growth

rate and

_{body shape respond}

to mass selection.

_High

backed _carp are also considered more

aesthetic,

with a market

preference

in certain areas.

The paper

presented

here is based on a thesis of the senior author

(Ankorion,

1966).

One of the aims of this

_{investigation}

was to

_study

the inheritance of the ratio

body

height/body

length,

and its correlation with

_growth

rate.

MATERIALS AND METHODS

The realized

_heritability

of the ratio

_{height/length}

was estimated in a bidirectional mass selection

_experiment.

&dquo;Height&dquo;

is here defined as the maximum

_height

of the

fish,

measured from the anterior base of the dorsal fin to the anterior base of the

pelvic

fin.

_{&dquo;Length&dquo;}

is standard

_length,

measured from the snout to the base of the

caudal fin. Selection was carried out in a commercial

_production

_pond

at the fish

farm of Gan

_Shmuel,

on market sized fish

(then

about 500

g).

The

pond

was stocked

with a

sample

of crossbred

_fry.

The _parents of this cross consisted of 4 females of the Beith Zera

isolate,

3 males of the

_Misgav

isolate and a further 3 males of

the Aielet isolate

_(Wohlfarth

et

al,

1965).

The base

_population

thus consisted of

a mixture 2

crossbreds,

with a common female _parent. Selection thresholds were

determined from measurements of

_height

and

_length

carried out on a

_sample

of

100 fish. Fish with a

height/length

ratio of < 0.365 or > 0.420 were defined as

experimental

groups consisted of 33 up selects

(3%),

49 down selects

(5%);

and 48

control

_fish,

_randomly

taken

_prior

to selection.

_During

_selection,

the data on

_height

and

_length

were

immediately

converted to

_ratios,

and used as selection criteria

(up

selects,

down selects or

rejection),

and not noted. The 3 groups of fish were taken

to the research station at

_Dor,

_{differentially}

_marked,

_separated

into females and

males and grown

separately

till the

_following

_spring.

In

_April

of the

_{following year,}

3 _{separate spawns} were

_{arranged by}

_re-uniting

the females and males of each _group

in a _separate

_{spawning pond.}

A random

_sample

of

_fry

from each

_{spawning pond}

was transferred to a _separate

_nursing

pond.

The nursed

fingerlings

were marked

differentially,

and stocked into 3

_replicated

communal

_testing

_ponds,

situated in

the fish farms Beit

Zera,

Nir David and Gan Shmuel. The

_methodology

of

_genetic

testing

in communal

_ponds

is described

_by

Wohlfarth and Moav

_(1985).

Several further

_genetic

groups of common _carp, stocked into these

ponds,

are

regarded

as

part of the common environment and

_ignored

in this

_{presentation,}

since

they

are

The test was terminated after about 4 months

_by

_draining

the

_ponds,

_removing

all the

_fish,

and

_sorting

them

_according

to their group marks. The fish of each

group were

counted, weighed

and the

_height

and

length

of each was measured

individually

and noted. This enabled

_computing

_{survival, growth, height, length}

and

the

_{height/length}

ratio of these 3 groups of fish. The realized

_heritability

of relative

height

was estimated from the ratio of selection _{response to} selection differential and the standard error of the estimate was calculated

according

to Hill

_(1971).

The correlated _response of the _component traits

_(height

and

_length)

to selection for the

height/length

ratio was estimated from mean differences in these traits between selected and random

_samples.

RESULTS

The results of this test, carried out in 3

_{communal testing}

_ponds

are shown in

table I.

_Previously

these _groups had been nursed in _separate

_nursing

_ponds

to a

random variation in mean

_{weights among}

the test groups, that of the control

being

. somewhat

_higher

₍₄₀

_g)

than those of the _up and down select _groups

₍₂₅

and _{29 g}

respectively).

Survival of fish was between 75 and 90% with no

_significant

differences

between the _groups. The _apparent survival of >100% in one case

(control,

Beith

Zera),

was

_probably

a result of error in

_identifying

fish at harvest. Mean harvest

weights

at Beith Zera and Nir David were close to market

_weight

_(of

that

_time);

that at Gan Shmuel was much lower.

Correcting

observed

_{weight gains}

Observed

_{weight gains}

_(final

_{weight -}

initial

_weight)

of each _group were corrected

for the deviations of their initial

_weight,

with the aid of a

predicted

correction factor

computed separately

for each

_pond

_(Wohlfarth

and

_Milstein,

_1987).

The

_predicted

correction factors were

_{4.49, 4.24}

and 3.86 for the

_ponds

at Beith

Zera,

Nir David and Gan

_{Shmuel, respectively.}

Observed

_weight

_gains

were corrected with the aid of

the

_equation:

Y’ =

Y-b(X -X.),

where Y’ and Y = corrected and observed

weight

gains,

respectively;

X and X. = initial

weight

of _a

given

genetic

group and mean

initial

_weight

of all tested _{groups, respectively;} and b = the

appropriate

correction factor

_(Wohlfarth

and

_Moav,

_1985).

Realized

_heritability

The results of bidirectional selection for

_{body shape}

are shown in

_figure

2. In the

parent

generation,

the selection differentials of the up select and down select groups

deviated

_by

0.049 and 0.030 units

_respectively

around the mean. In the _progeny, a

selection response was

generated

in both

_directions,

in each of the 3

_{replications.}

Estimates of realized heritabilities are shown in table II.

_Up

selection

_generated

a

larger

response than down

selection,

similar to the

_higher

selection differential of the

up selection group. Estimates of realized

heritability

(selection response/selection

differential)

generated

in this

_study

were 0.47 !

_0.06,

0.33 ! 0.10 and 0.42 t 0.03

for _up

_selection,

down selection and simultaneous bidirectional selection. Correlated response

of height

and

_length

Data on

_height

and

_length

of

_progenies

of up

selects, down

selects and controls are

shown in table III. Selection for the

_{height/length}

ratio

_generated

a _{response in}

both

_height

and

_length.

For each

_sample

and in each

_pond,

fish of the up select line

had an

_absolutely

_greater mean

_height

and an

_absolutely

smaller mean

_length

than

fish of the control _group. The

_opposite

is the case for fish of the down select line.

A direct

_comparison

between correlated _responses of

_height

and

_length

_requires

standardization of the

_results,

since mean

_length

of the control group is close to

3 times as

high

as mean

height.

Standardization was carried out

_{by dividing}

_response

by

the absolute value of the control _{group, in} each case

(see

relative response, last 2 columns in table

_III).

These show that the correlated response of

length

is about

3.5 as

_high

as that of

_height,

and that the correlated response to up selection is

about 2.5 as

_high

as that to down selection. Realized heritabilities of

_height

and

length

could not be

_estimated,

since absolute data on

_height

and

_length

were not

Correlation between

_growth

and

_{body shape}

by

the down select

_line,

ie the _group with the lowest ratio of

_{height/length,}

but no

significant

difference was shown among lines within

replication.

DISCUSSION

Heritability

of the ratio

_{height/length}

A

_{single cycle}

of bidirectional selection

_generated

a selection _response in both

directions. Estimates of realized

_heritability

were 0.47 and 0.33 for up and down

selection

_{respectively.}

It is

_possible

that these are overestimates. The

_population

on which selection was

practised

consisted of 2

crossbreds,

with a common female

the

_{height/length}

ratio between the 2 crossbreds

_might

have existed

_by

chance.

The _up selects could therefore have included a

high frequency

of the crossbred

with the

_higher

_{height/length}

_ratio, and

_similarly

for the down

selects,

yielding

higher

heritabilities than

_expected

within a

_single

isolate. With such

heritabilities,

it appears

possible

to

_change

the

_{body shape}

of common _carp

_fairly

_rapidly.

Differences in

_{body shape}

_among different carp races and isolates are

presumably

due to differences in selection intensities and number of

_generations

of selection

practised

in the _past.

_Among

our

_genetic

stocks of common _carp, a line introduced

from Nasice in

_Yugoslavia

_possesses a

particularly high

ratio of

height/length.

This

stock was

_subjected

to several

_generations

of mass selection for a

high

height/length

ratio

_previous

to its introduction to Israel

_(Moav

et

al,

1975).

Similar selection

was not carried out on our other stocks and these _possess a much lower ratio of

height/length.

The existence of environmental and

_genetic

_components of the trait

_{height/length}

seen

_{by comparing}

the three

_{replications.}

The lowest

height/length

ratio was found

in Gan

_Shmuel,

ie in the

_pond

with the slowest

_growth

and therefore the worst

environment. The

_high

estimates of realized

_{heritability generated}

in this

_study

indicate a _strong additive

_genetic

_component in the total variation of the trait

height/length.

Response

to

_selection,

realized

_{heritabilities,}

correlated _responses The

_genetic

_response to bidirectional selection of the

_{height/length}

ratio

_generated

high

estimates of realized heritabilities

_(between

0.47 &mdash;

_0.35;

see table

II).

Up

and

down selections

_generated

estimates of the same order of size. Correlated responses in the _component traits

_(table

_III)

are

_presumably

a result of differences

generated

by

selection for the

_{height/length}

ratio. It is not

_possible

to estimate and compare

realized heritabilities of absolute

_height

and absolute

_length

in this

_{investigation,}

since data of these absolute values were not noted

_(see

Materials and

_Methods).

This

_comparison

is of interest when

_considering

whether the

_{height/length}

ratio is

most

_{effectively improved by}

direct selection for the ratio or

_by

selection for the

component traits.

Selecting

for a ratio between 2 traits

Ratios between different

_traits,

such as feed conversion

_ratio,

proportion

of

body

fat, egg

mass/body

weight,

etc have served as selection

_goals

in farm animals

(beef

cattle,

broilers, etc)

and

_laboratory

animals

_(mice,

flour

_beetles,

_etc).

_Selecting

for

improvements

in ratios between 2 traits _may be

_{complicated by}

the

_{disproportionate}

fashion in which selection _pressure is exerted on _component traits and their different

response to selection. It is influenced

_by

the

_{phenotypic variability}

of the 2

_traits,

their

_{heritabilities,}

and the correlation between numerator and denominator traits.

Alternatives to selection for a ratio between 2 traits include selection for either

numerator or denominator

_traits,

or simultaneous selection for both

_traits,

involving

linear selection indices. Use of selection indices may be more effective in

generating

a selection _response in a ratio than direct selection for that

_ratio,

when the heritabilities of the 2

_component

traits are

unequal

and their

_phenotypic

correlations

low,

and at

_high

selection intensities

_{(Gunsett, 1984).}

This was demonstrated in an

investigation

on selection for _egg

mass/adult

_weight

ratio in Triboleum castaneum

(Campo

and

_{Rodriguez, 1990).}

In a

_study

on feed conversion ratio in beef cattle

however,

selection _responses

_{generated by}

direct selection for the ratio or selection

by

means of an index were similar

(Davis,

1987).

In our

study,

both

height

and

length responded

to mass selection

_(see

table

_III),

the relative _response of

_length

being larger

than that of

_height.

Since the selection differentials of these 2 traits

were not

estimated,

it is not

_possible

to estimate their

heritabilities,

or _{to compare}

them to the heritabilities of the

_{height/length}

ratio. As a

_result,

available data do

Association between

_{body shape}

and

_growth

The

_{apparently negative}

association between the

_{height/length}

ratio and

_growth

is

_{probably meaningless,}

since differences in

_growth

_among test groups were not

significant.

This

_negative

correlation is however consistent with the results of

a similar

study

_among Polish _carp

(Stegman, 1968).

In _{any case,} there are no

indications that

_growth

rate may be

_{improved indirectly by selecting}

the

_highest

backed individuals.

REFERENCES

_,

Ankorion Y

₍₁₉₆₆₎

Studies on the

_heredity

of some

morphological

characteristics in

the common _carp

_(Cyprinus

_carpio

_L).

M Sc

_thesis,

Hebrew

_University,

Jerusalem

66 _p

_{(in Hebrew)}

Anwand K

₍₁₉₆₁₎

Biometrische

_{Untersuchungen}

an

Karpfen

aus der Teichwirtschaft

Peitz. Z Fisch

_Hilfswiss

10

_NF,

69-104

Campo JL, Rodriguez

M

₍₁₉₉₀₎

Relative

_efficiency

of selection methods to

_improve

a ratio of two traits in Tribolium. Theor

_Appl

Genet

_80,

343-348

Davis ME

_{(1987) Divergent}

selection for

_post-weaning

feed conversion in beef cattle:

predicted

response based on an index of feed intake and

_{gain vs}

feed:

gain

ratio.

J Anim Sci

_65,

8861895

Gunsett FC

₍₁₉₈₄₎

Linear index selection to

_improve

traits defined as ratios.

J Anim Sci

_59,

1185-1193

Hill WG

_{(1971) Design}

and

_efficiency

of selection

_experiments

for

_{estimating genetic}

parameters. Biometrics

_27,

293-311

Hofmann J

₍₁₉₇₅₎

Der Teichwirt. Zucht und

_Haltung

des

_Karpfens.

Paul

Parey,

Hamburg,

4th

_edn,

312 _p

Mann H

₍₁₉₆₁₎

Fish cultivation in

_Europe.

In: Fish as Food

(Bergstrom

G,

ed)

Academic

Press,

New

_York,

vol

_1,

70-102

Moav

R,

Hulata

_G,

Wohlfarth G

₍₁₉₇₅₎

Genetic differences between the Chinese and

_European

races of the common _{carp 1.}

Analysis

of _{genotype -} environment

interaction for

_growth

rate.

_Heredity

_34,

323-340

Stegman

K

₍₁₉₆₈₎

The estimation of the

_quality

of _carp

_by

means of

length/height

ratio and relative

_{weight gains. FAO}

Fish

_Rep

44

_(4),

_160-168

Willer A

₍₁₉₃₃₎

Uber die Zuchtziele in der

_{Karpfenteichwirtschaft.}

Mitteilungen

der Deutschen

_{Landwirtshaftsgesellschaft}

_10/11,

1-3

Wohlfarth

_G,

Lahman

_M,

Moav

_R,

Ankorion Y

₍₁₉₆₅₎

Activities of the

_Carp

Breeders Union in 1964.

_Bamidgeh

_17,

9-15

Wohlfarth

_GW,

Milstein A

₍₁₉₈₇₎

_Predicting

correction factors for differences in initial

_weight

_among

_genetic

_groups of common _carp in communal

_testing.

Aquaculture

60,

13-25

Wohlfarth

_GW,

Moav R

₍₁₉₈₅₎

Communal

_testing,

a method of

_testing

the

growth