Esterase variation among Argentine populations of Trimerotropis pallidipennis (Orthoptera)

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Esterase variation among Argentine populations of

Trimerotropis pallidipennis (Orthoptera)

Va Confalonieri, Jc Vilardi, Bo Saidman

To cite this version:

Original

article

Esterase

variation

among

Argentine populations

of

_{Trimerotropis}

_{pallidipennis}

(Orthoptera)

VA Confalonieri, JC

_Vilardi,

BO Saidman

Universidad de Buenos Aires, Faculdad de Ciencias Exactas y Naturales

Departamento de Ciencias Bioldgicas, I128 Buenos _{Aires, Argentina}

(Received

4 _{January 1989; accepted} 10 March

₁₉₉₀₎

Summary - Isozyme studies were carried out in 3 populations of _{Trimerotropis}

palli-dipennis from Tucumin and San Luis Provinces

_(TU,

SLi and

_SL

₂

₎

_(Argentina).

The

purposes of this study were: determination of _{the numbers of genes and} alleles involved in the _production of the _isozymes and their _frequencies, detection of

_diagnostic

loci for

population identification and _measuring the _{genetic variability} and the

_degree

of _genetic differentiation among populations. With this aim, the esterase

(EST)

isozyme system was studied and 6 loci were _analysed

(Est

1 to Est

6).

The EST _patterns allowed population

samples from different _{biogeographic provinces} to be

_{distinguished.}

_Qualitative differences between populations were observed in the _expression of some loci

(Est

_1, Est 2 and Est

3)

and the presence of additional alleles for other ones

_(Est

5 and Est

6),

characterizing

TU, were also detected. Therefore, this differentiation among populations refers to both gene expression and allelic frequencies which may represent 2 distinct responses to

envi-ronmental differences. Possible correlations of _genetic and chromosomal variation are also discussed.

orthoptera / isozyme / esterase _{/ Trimerotropis /} genetic variation

Résumé - Variabilité des estérases dans des populations argentines de Trimerotropis

pallidipennis (Orthoptères). Trois _populations de _{Trimerotropis pallidipennis} situées dans les _provinces de Tucumdn et San Luis

_(TU,

SLl et

_SL

₂

₎

_{(République argentine)}

ont été étudiées _afin de déterminer le nombre de _gènes et d’allèles responsables de la _synthèse des isoenzymes estérasiques, d’identifier les locus pouvant caractériser des _populations, et

d’évaluer la variabilité et le _degré de _{différentiation génétique} entre les populations. Six locus _probables

_(Est

1 à Est

₆₎

ont été reconnus. Les enzymogrammes estérasiques ont

permis de _distinguer les échantillons des _{différentes provinces biogéographiques,} tandis que

ceux de la même _province ne _{pouvaient pas} être distingués. Il existe, entre les populations,

des

_différences

_qualitatives dans _{d’expression} des locus Est _1, Est 2 et Est 3 et ainsi que

dans la _présence d’allèles

_{différentiels}

aux locus Est 5 et Est 6. Cette différence entre les

populations se _manifeste aussi bien dans _{l’expression} des gènes _que dans les fréquences

aldéliques, ce _{qui pourrait représenter 2 types} de _{réponses adaptatives.} Les corrélations

entre la variabilité génétique et _{chromosomique} sont discutées.

INTRODUCTION

Grasshopper

species

of the genus

Trirn,erotropis

are of interest from an

_evolutionary

genetics

standpoint

because

_they

show chromosomal variation with _respect to

the

_position

of the centromere

_{(White, 1973),}

_usually

considered as

produced

by

pericentric

inversions

_(Hewitt,

_{1979; John,}

_1983).

Most of the

_species

of this genus inhabit arid

regions

from Western North

America;

T

_{pallidipennis}

is one of the few

_{Trimerotropines}

to have

_successfully

extended its distribution to Andean South America

_{(White, 1973).}

_Argentine

populations

studied are

_polymorphic

for

_pericentric

inversions

_(Mesa,

_1971;

Vaio et

al,

1979;

Goni et

_al,

_1985;

_{Confalonieri,}

_1988;

Confalonieri and

_Colombo,

_1989).

Goiii et al

₍₁₉₈₅₎

observed for this

_species

a

_geographical

_pattern of chromoso-mal

_{polymorphisms}

associated with neither

_{phytogeographical}

nor climatic charac-teristics. Clinal variation

_along

an altitudinal

_gradient

of these

_{polymorphisms}

was

recently

found

_{(Confalonieri}

and

_Colombo,

_1989).

There

_is,

_therefore,

a need for a more exhaustive

_ecological

_approach.

This

_requires

a

parallel

_study

of

_chromosomal,

genetical

and

_ecological

variation.

In

_spite

of the known usefulness of

_isozymal

studies to

_{population genetics,}

_only

a few studies

_(Moran

et

al, 1980;

Gill,

1981; Halliday

et

_{al, 1983;}

Nevo et

_al,

_1984;

Chapco

and

_Bidochka,

₁₉₈₆₎

have been

_{performed dealing}

with

_allozyme

variation in

_grasshopper

_species.

In this

_work,

_isozyme

studies were carried out in T

_{padlidipennis}

with the pur-poses of:

a)

estimating

the number of

_responsible

_genes and their allelic

_frequencies;

b)

detecting diagnostic

loci for

_populations;

_c)

_determining

_genetic

_variability

and the

_degree

of differentiation between

_populations;

_d)

_correlating

_genetic

and chro-mosomal variation.

This paper reports the results obtained from the

_study

of the esterase

_(EST)

isozyme

system in 3

_populations

of T

_{pallidipennis.}

MATERIALS AND METHODS

Samples

of adult

_grasshoppers

were collected from TucumAn

(TU)

and San Luis

(SL,

and

_SL

₂

_,

_Republica

_Argentina.

TU is located at Amaicha del Valle

_{(2 040}

m above sea

_level);

_SL,

is situated on the National Road No

7,

km

_792.5,

and

SL

2

on the same road at km 816

₍₅₆₀

and 440 m above sea level

respectively).

The

populations

sampled belong

to 2 different

_{biogeographic}

_provinces

of the Chaco

Dominion, Neotropical

Region

(Cabrera

and

_Willink,

_1973).

TU is in the

_Prepuna

while both SL

_populations

are situated in the Chaco

_{Biogeographic}

Province

_{(fig 1).}

Twenty-four

individuals from

_TU,

29 from

_SL

₁

and 20 from

_SL

₂

were collected.

After removal of the testes for chromosomal

_analysis,

the

_grasshoppers

were frozen and stored in

_liquid

air until enzyme assays were done.

Extracts were obtained from the eviscerated head and thorax. Each individual

was

_{thoroughly homogenised}

in

_{approximately}

0.6 ml of 0.1

_mol/1

_{Tris-HCI, pH}

7.1.

The

_homogenate

was

_centrifuged

at 7 000 _rpm for 10 min in a

_{refrigerated centrifuge.}

The

_{electrophoresis}

was conducted in 7%

_{polyacrylamide}

horizontal

_gels

accor-ding

to the

_technique

of Cordeiro

_(1974).

The _system of

_gel

and _tray buffers was

Staining

techniques

are described

by

Cladera

(1981).

Different substrates

(esters)

were used to characterize the different bands:

_a-naphthyl

acetate

_(a-NA),

,Q-naphthyl

acetate

_(/3-NA),

_a-naphthyl

laurate

_(a-NL),

_{a-naphthyl butyrate}

(a-NB),

a-naphthyl

oleate

_(a-NO),

_a-naphthyl

_propionate

_(a-NP)

and

_naphthol

AS-D

acetate

_(AS-D).

The

_{interpretation}

of the

_genetic

variation in

_{electrophoretic}

_patterns is

inferen-tial

_according

to

Saidman

and

_Naranjo

_(1982).

Bands are labelled in

_capital

letters and numbered

_according

to

_decreasing

electrophoretic

mobilities. Loci are named with an initial

capital

letter followed

by

lowercase letters and numbered

_according

to

_decreasing

mobilities of

_isoenzymes.

Alleles are named with the

_symbol

of their loci and an index

_according

to

_decreasing

RESULTS

The results obtained with different substrates are

_presented

in table I. Bands could be

_{grouped according}

to their

_ability

to react with different esters: EST 1 -EST 2 - -EST

3;

EST 4 -

EST

_5;

EST

_6;

EST 7 - EST

_8;

EST

_9;

EST 10 - EST

11; EST 12. The

probable

loci and alleles

implicated

in the

_genetic

determination

of bands were inferred

_taking

into account the combinations of the differential substrate a!nities.

EST 1 and EST 2 are invariable and _may be

_{produced by}

2

_monomorphic

loci:

EST 1 and EST 2

_{(fig 2).}

EST 3 and

_EST

_{4 show}

similar affinities and

_migrate

very

close to each other. Three kinds of _patterns were observed: EST

_3,

_EST

_and

EST 3 with EST

.!.

On these

_grounds

the bands were considered as

allozymes

coded

_by

1 locus with 2

_alleles,

EST 3

1

and

EST

F

_{respectively.}

EST 1 band was never observed in the TU

_population,

and the

_expression

of bands EST 2 to

_EST

_{l in}

this

_sample

was _{very poor} or

_{absent, showing}

some

degree

of individual variation.

EST

_5,

EST 6 and EST 7 are also considered as

_{allozymes. They appeared}

in

the

_following

combinations: EST

_5;

EST

_6;

EST

_7;

EST 5 with EST

6;

EST 5 with

also indicated in 2b. The

_{corresponding}

alleles were

_named;

EST

l!l,

EST

4

2

and

ES

T

43.

EST

_8,

EST 9 and EST 10 react

_similarly

to a- and

!i-NA.

EST 9 and EST 10 also gave similar

staining

affinities with the rest of the substrates

_employed.

Because of its low

frequency,

EST 8 was absent in the individuals

_assayed

with the latter

_substrates,

and therefore its affinities could not be confirmed.

_Despite

this

_fact,

these results

_along

with the combinations observed

_(EST

8;

EST

_9,

EST

10;

EST 8 with EST

9;

EST 8 with EST

_10;

EST 9 with

EST 10;

absence of

bands) may

correspond

to those

_expected

for a locus with 4

alleles,

3

codominants,

EST 5

1

,

EST

_5’

_z

_,

EST

5!

and 1 null EST

5°.

The latter in a

_homozygous

condition is

characterized

_by

the absence of bands. All

_phenotypes

are shown in

_figure

2 _except

the combination EST 8 - EST 10 which

_appeared

in other

_gels

not

_depicted

in this

figure.

EST 11 and EST 12 varied

_showing

the

_following

combinations: EST

_11;

EST

_12;

EST 11 with EST 12.

_They

were considered as

_{produced by}

1 locus with

2 alleles:

EST 6

1

and EST 61

_{(fig 2).}

The bands

_{corresponding}

to EST 6 could not

be

_properly

ascertained in 1 individual from TU and therefore it was excluded from the

_analysis

of this locus.

Five additional

bands,

4 between

_EST

_{4 and}

EST 5 and 1 between EST 10 and EST 11 were also found. Their

_respective

affinities differentiated them from those of

EST 1 to EST

_12,

but their _patterns were not constant

_enough

to be

_{unequivocally}

analysed.

Assuming

that this

_genetic

_{interpretation}

of bands is _correct,

_{phenotype and/or}

genotype

frequencies

for each locus were determined

(table II).

_Then,

allelic

frequencies

were estimated

_{by counting}

or, in the case of the EST 5 locus which has a null

_allele,

_by

the method of Neimann-Sorensen

(1956)

(table III).

In

addition,

mean

_frequencies

of

_{heterozygotes}

_per locus were also estimated and are indicated in table III.

From the 6 loci

_analysed,

4

_{displayed qualitative}

differences between TU and both SL

_populations.

Thus,

EST

_1,

EST 2 and EST

_3,

_{clearly expressed}

_SL,

and

SL

2

,

were either absent or almost non detectable in TU. EST 6 was

_polymorphic

in the latter and

_monomorphic

in the other 2

_populations.

The allelic

_frequencies

at EST

_3,

_EST

_{4 and}

EST 5 were

compared

_among

populations by

means of

_contingency

tables

(table III).

Allelic

frequencies

of

EST 3 from both SL

populations

were not

_{statistically}

different

_and,

at the EST

4 locus,

differences were also not

_significant

when all

populations

were considered

(though

in this case the X2for

vs

1

SL

SL

2

was

significant

at the 5%

_level).

However,

EST 5 locus

_{significantly}

differentiates TU from both SL

_populations.

This is due

to the fact that EST

_5°,

the most

_frequent

allele in

_SL

_I

and

_SL

₂

_,

was absent in TU.

_Also,

the EST 52

_frequency

was

_high

in TU and low in the other

_samples.

The average

expected heterozygosity

was also similar for

SL,

and

SL

2

(about

0.24)

and

_clearly

different from that of TU

_{(0.505) (table III).}

In all

_populations,

observed

_genotypic

_frequencies

were

compared

with

Hardy-Weinberg expectations by

means of

_chi-square

tests for the loci EST _3,

EST

4 and

EST 6

_{(table II).}

These statistics were further

_{applied only}

to the data of EST 5

DISCUSSION

The

_{genetic interpretation}

of bands studied was

_inferential,

but the

_hypotheses

put forward _agree with the fact that in all cases where statistical

_comparisons

could

be

_performed,

observed

_{genotypic frequencies}

fit _{very well} with those

_expected

according

to the

_{Hardy-Weinberg}

law.

Since 5 of the 6 loci

analysed

showed marked differences in either _gene

_expression

on allelic

_frequency,

esterase zymogrames could be used to

_{identify populations}

from different

_(but

not from the

_same)

_provinces.

An additional difference between TU and SL

_populations

is the level of

_variability

of these loci. In the

_former,

H has more than twice the value it has in the latter.

The virtual lack of

_expression

of EST 1 to EST 3 loci in TU may be

explained

-

1)

Mutations can

_{produce changes}

in the amino acid _sequence of

polypeptide

chains

_affecting

the

_specific

_activity

_(null

alleles or alleles with a _very

slight

expression).

-

2)

Lower amounts of

_enzymatic

molecules with the same structure are

possibly

a consequence of:

a)

a

_regulatory

_gene;

b)

different factors in the environment which

produce

the activation

_(or

inacti-vation)

of certain

_regulatory

_gene(s);

c)

the existence of chromosome inversions fixed in this

_population

that silence

these loci

by position

effects;

The first

_{hypothesis implies}

that alternative alleles for 3 out of 6 loci

_analysed

are fixed in different

_{populations. However,}

the most common situation among

conspecific populations

is that 1 allele is the most

_frequent

in almost all of them

(Lewontin, 1979).

Besides,

this

_hypothesis

seems to be untenable

_according

to the

parsimony

principle.

The

_hypothesis

2a

_implies

a mutation

_affecting

_only

a

_{single gene}

(controlling

EST 1 to EST 3

_loci)

which seems to be a

_simpler

and more

_{likely explanation,}

though

2b and 2c are also

_acceptable.

The

_hypothesis

2b is

_plausible

because esterases are _enzymes

_{frequently acting}

on external substrates

_proceeding

from

_ingestion.

The

_{precise plant}

_species

that

constitutes

this

_{grasshopper’s}

food in

_Argentina

is not known. Possible candidates

are annual

_plants

associated with

_species

of the genus Larrea

(creosote bush) (Otte

and

_{Joern, 1975; Wallner,}

_1987).

As TU and both SL

_populations

are located in

will not be the same. In

_fact,

L divaricata is

_widely

distributed over the arid and semiarid

_regions

in

_Argentina,

but

_{morphological}

differences are

_readily

observed

between

_plants

.at different altitudes. This may be a consequence of both

genetical

and

_{physiological}

adaptations

(Hunziker,

personal

communication).

The

plants

associated with the creosote bush which constitue T

_{paddidipennis}

food are also

expected

to

_adapt

to the

_{corresponding}

environment.

_Therefore,

distinct enzyme

expression between the

_orthopterans

_{feeding upon}

them is not

_surprising.

The

_hypothesis

2c is based on the

_{high frequency}

of inversion

_{polymorphisms}

and chromosomal differentiation among T

pallidipennis populations

(Vaio

el

al,

1979;

Goni et

_al,

_1985;

_{Confalonieri, 1988;}

Confalonieri and

_Colombo,

_1989).

A simi-lar kind of differentiation between the

_{populations reported}

here was also evident

when chromosome

_{investigation}

was carried out

(Confalonieri

et

_al,

_submitted).

The 3

_populations

were

_polymorphic

for 3 centric shifts which involved 4 medium

chromosomes;

when

_they

were

_{statistically compared,}

differences with respect to

inversion

_frequencies

were

_{highly significant among}

all

_populations

_except SL ones.

Moreover,

some chromosome

_arrangements

were at

_high

_frequencies

in TU and

ab-sent or at _{very low}

_frequencies

in

_SL

_I

and

SL

2

,

respectively. Therefore,

these results

are in _agreement with the last

_hypothesis

_(2c)

because if 2

_populations

have

diffe-rent fixed

_inversions,

or are of very different

frequencies,

position

effects are not an

unexpected phenomena. Finally,

inversion

_frequencies

from 15

_populations

(inclu-ding

TU,

SL,

and

SL

2

from

_Argentina)

were correlated in a _very

significant

fashion with altitude

_{(Confalonieri}

and

_Colombo,

1989; Confalonieri,

in

_{preparation),}

sug-gesting

the action of natural selection in the maintenance of these

_{polymorphisms.}

Therefore,

as TU and both SL

_populations

have _very different inversion

frequen-cies,

most

_probably

as a result of

_living

at different

_altitudes,

their chromosomal

variation

_might

also be related to

_genetical

differentiation.

ACKNOWLEDGMENTS .

The authors wish to express their sincere

_gratitude

to H Hunziker for his

guidance,

constant _{encouragement} and critical

_reading

of the

_manuscript

and to

PC Colombo for his

_generousity

in

_providing

material from Tacumin. We also thank the anonymous referees for their valuable

suggestions.

The financial _support from

_Consejo

Nacional de

_{Investigaciones}

Cientificas y

T6cnicas,

Secretaria de

Ciencia _y T6cnica

_(Argentina)

_through

_grants to H Hunziker and A

_Naranjo

is also

_{acknowledged.}

REFERENCES

Cabrera

_AL,

Willink A

₍₁₉₇₃₎

_Bio

_g

_eografica

de Am!rica Latina.

_Org

Est Amer

Washington,

DC

Chapco

W,

Bidochka MJ

₍₁₉₈₆₎

Genetic variation in

_prairie

_population

of

Melano-plus

sanguinipes,

the

_migratory

_grasshopper.

_Heredity,

_56,

397-408

Cladera JL

₍₁₉₈₁₎

Genetica de alozimas en Ceratitis

_cawitata.

I. Dos alelos de la esterasa

_pupal.

Mendeliana, 5,

33-38

Confalonieri VA

₍₁₉₈₈₎

Effects of centric shift

_{polymorphisms}

on chiasma conditions

Confalonieri

_VA,

Colombo PC

₍₁₉₈₉₎

Inversion

polymorphisms

in

_{Trimerotropis}

pallidipe!nis:

Clinal variation

_along

an altitudinal

_{gradient. Heredity,}

_62,

107-112

Cordeiro AR

₍₁₉₇₄₎

Varibilidade e

_{regulacao gen6tica}

nos _processos

evolutivos.

Tese

para conc Prof Titular.

_Dep

Genet Univ Fed Rio Grande do Sul. Porto

_Alegre

Gill P

₍₁₉₈₁₎

_{Heterozygosity}

estimates in the

_grasshopper

_Chorthippus

br!nneus

(Thunberg).

Heredity, 46,

269-272

Goni

_B,

De Vaio

_E,

Beltram

M,

Leira

_MS,

Crivel

_M,

Panzera

_F,

Castellanos

_P,

Basso A

₍₁₉₈₅₎

_Geographic

_patterns of chromosomal variation in

_populations

of the

_grasshopper

_{(Trimerotropis pallidipennis)}

from Southern

_Argentina.

Can J

Genet

_{Cytod 27,}

259-271

Halliday

RB,

Barton

_NH,

Hewitt GM

₍₁₉₈₃₎

_{Electrophoretic analysis}

of a chromo-somal

_hybrid

zone in the

_grasshopper

Podisma

_pedestris.

Biol J Linn

_{Soc, 19,}

51-62

Hewitt GM

₍₁₉₇₉₎

Orthoptera: Grasshoppers

and crickets. Animal

_{Cytogenetics.}

Vol 3.

_Stuttgart:

Gebruder

_Borntraeger,

_Berlin,

170 p

John B

₍₁₉₈₃₎

The role of chromosome

_change

in the evolution of

_orthopteroid

insects. In: Chromosomes in evolution

_{of eukariotic}

_groups,

_{(Sharma AK;}

Sharma

AM,

eds),

I,

1-114. CR C

_Press,

Florida

Lewontin RC

₍₁₉₇₉₎

La base

_genetica

de la evoluci6n. Ediciones

_Omega

SA Barce-lona

Mesa A

₍₁₉₇₁₎

Polimorfismo cromos6mico en

_{Trimerotropis pallidipennis}

(Orthop-tera-Acridoidea-Oedipodinae).

Rev Peru

_Entom,

_14,

2

Moran

_C,

Wilkinson

_P,

Shaw C

₍₁₉₈₀₎

_Allozyme

variation across an arrow

_hybrid

zone in the

_grasshopper

Caledia _captiva.

_Heredity,

_44,

69-81

Neimann-Sorensen A

₍₁₉₅₆₎

Blood _groups and breed structure as

_{exemplified by}

three Danish breeds. Acta

_Agric

Scand

_6,

115-137

Nevo

_E,

Belles

_A,

Ben-Shlomo R

₍₁₉₈₄₎

_{Evolutionary dynamic}

of

_genetic

_diversity.

Lecture Notes in Biomathematics.

_(Mani

_GS,

_ed)

_53,

13-213

Otte

_BO,

Joern 1

₍₁₉₇₅₎

Insect

_{territoriality}

and its evolution:

_Population

studies of desert

_grasshoppers

on creosote bushes. J Anim Ecol

_44,

29-54

Saidman

_{BO, Naranjo}

CA

₍₁₉₈₂₎

Variaciones de esterasas en

_poblaciones

de

Prosopis

ruscifolia

(Leguminosae).

Mendeliana,

5, 61-70

Schaal

_BA,

Anderson WW

₍₁₉₇₄₎

An outline of

_techniques

for starch

_gel

electropho-resis of _enzymes from the American _oyster

_{(Crassostrea virginica).}

Gem

_Georg

Mar Sci Ctr Tech

Rpt

Ser No _74, 3

Vaio ES

de,

Goni

_B,

_Rey

C

₍₁₉₇₉₎

Chromosome

_{polymorphisms}

in

_populations

of the

_{grasshopper Trimerotropis pallidipennis}

from Southern

_Argentina.

Chromo-soma

_(Bers)

_{71, 371-386}

Wallner WE

₍₁₉₈₇₎

Factors

_affecting

insect

population

dynamics:

Differences between outbreak and non-outbreak

_species.

Ann Rev Entomol

_32,

317-340