Body size inequality of carabids along an urbanisation gradient
Full text
UNCORRECTED PROOF
Basic and Applied Ecology ](]]]])]]]—]]]
Body size inequali y o ca abids along an
u banisa ion g adien
Un e schiede de Ko¨ pe g o¨ße bei Ca abiden
en lang eines U banisa ionsg adien en
Tibo Magu a
a,
,Be´la To´ hme´ e´sz
b
,Ga´bo L. Lo¨ ei
c
a
Ho oba´gy Na ional Pa k Di ec o a e, H-4002 Deb ecen, POB. 216, Hunga y
b
Depa men o Ecology, Uni e si y o Deb ecen, H-4010 Deb ecen, POB. 71, Hunga y
c
Depa men o In eg a ed Pes Managemen , Danish Ins i u e o Ag icul u al Sciences, Flakkebje g Resea ch Cen e,
DK-4200 Slagelse, Denma k
Recei ed 3 Ma ch 2005; accep ed 8 Augus 2005
KEYWORDS
G ound bee les;
Dis u bance;
Globene p ojec ;
Skewness;
Gini coe icien ;
Lo enz asymme y
coe icien
Summa y
Analysis o size inequali y can shed ligh on coexis ence mechanisms and help o
in e p e pa e ns in assemblages. We es ed se e al measu es o hei powe o
e alua e changes in ca abid body size along an u banisa ion g adien (ci y
pa k–subu ban a ea– u al), ep esen ing dec easing in ensi ies o human dis u -
bance. Ca abids we e collec ed by pi all aps o e wo ull ac i i y pe iods in
lowland oak o es pa ches in and nea he ci y o Deb ecen, Eas e n Hunga y.
The a e age alue o skewness was la ges in he u ban a eas compa ed o he
subu ban and u al ones, indica ing ha small indi iduals we e mo e p ominen in
he u ban a eas. The Gini coe icien also dec eased om u ban owa ds u al a eas,
sugges ing ha inequali y in body size o he ca abid assemblages dec eased along
he g adien . Howe e , nei he o hese ends was signi ican . The Lo enz
asymme y coe icien was signi ican ly highe in u al a eas compa ed o subu ban
and u ban a eas indica ing ha he e was a signi ican di e ence in inequali y and/
o asymme y o body size ac oss he g adien . This di e ence was p ima ily due o
mo e indi iduals wi h la ge body size in u al a ea. We sugges ha he obse ed
a ia ion in ca abid body size along he g adien is ela ed o habi a al e a ion
caused by u banisa ion.
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¨kologie.
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doi:10.1016/j.baae.2005.08.005
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E-mail add esses: magu [email protected] (T. Magu a), [email p o ec ed] (B. To´ hme´ e´sz), gabo [email p o ec ed] (G.L. Lo¨ ei).
UNCORRECTED PROOF
Zusammen assung
Die Analyse on G o¨ßenun e schieden kann die Koexis enzmechanismen beleuch en
und hel en, Mus e on Ansammlungen zu in e p e ie en. Wi un e such en
e schiedene Pa ame e au ih Po enzial die Ve a¨nde ungen de Ko¨ pe g o¨ße bei
Ca abiden en lang eines U banisa ionsg adien en (S ad pa k–Vo s ad gebie –la¨nd-
lich) zu e kla¨ en, de eine abnehmende In ensi a¨ de an h opogenen S o¨ ung
ep a¨sen ie e. Die Ca abiden wu den in Boden allen u¨be zwei olls a¨ndige ak i e
Pe ioden in Tie landeichenwa¨lde n und in de Na¨he de S ad Deb ecen im o¨s lichen
Unga n gesammel .
De du chschni liche We de Schie e wa in den s a¨d ischen Gebie en im
Ve gleich zu den o s a¨d ischen und la¨ndlichen am g o¨ß en und wies da au hin, dass
kleine Indi iduen in den s a¨d ischen Gebie en meh he o a en. De Gini-
Koe izien e inge e sich eben alls on den s a¨d ischen zu den la¨ndlichen
Gebie en und la¨ß e mu en, dass die Un e schiede in de Ko¨ pe g o¨ße in den
Ca abiden-Ansammlungen en lang des G adien en abnahmen. Keine diese T ends
wa jedoch signi ikan . De Lo enz-Asymme ie-Koe izien wa in den la¨ndlichen
Gebie en im Ve gleich zu den o s a¨d ischen und s a¨d ischen Gebie en signi ikan
g o¨ße und wies da au hin, dass es einen signi ikan en Un e schied in den
Ko¨ pe g o¨ßeun e schieden und/ode in de Asymme ie de Ko¨ pe g o¨ße en lang
des G adien en gab. Diese Un e schied wa o allem da au zu u¨ckzu u¨h en, dass
es in den la¨ndlichen Be eichen meh Indi iduen mi eine g o¨ße en Ko¨ pe g o¨ße gab.
Wi e mu en, dass die beobach e e Va ia ion in de Ko¨ pe g o¨ße de Ca abiden
en lang des G adien en mi de du ch die U banisa ion e u sach en Ve a¨nde ung
de Habi a e e bunden is .
&2005 Published by Else ie GmbH on behal o Gesellscha u¨ O
¨kologie.
In oduc ion
Rela ionships be ween body size and he s uc-
u e o animal assemblages ha e been he ocus o
much a en ion in ecological s udies. Body size is
co ela ed wi h many aspec s o li e his o y
( ep oduc ion a e, dispe sal, de elopmen ime,
e c.) (Pe e s, 1983). Body size also has a signi ican
impac on ecological in e ac ions, esou ce use,
and mo e indi ec ly, he pe iod o ac i i y, habi a
sui abili y, and nume ous o he pa ame e s (Pe e s,
1983). A change in body size, ei he in indi idual
species, o in he size dis ibu ion o he species
p esen in a habi a is also a pa ame e po en ially
indica ing di e en ypes o en i onmen al s ess
(McGeoch, 1998).
A numbe o an h opogenic ac i i ies, including
a ming, o es y and u banisa ion, ha e a signi i-
can impac on he en i onmen and c ea e pa ch-
wo ks o modi ied land ypes ha exhibi simila
pa e ns h oughou he wo ld (Poschlod, Bakke , &
Kahmen, 2005;Ul ich & Buszko, 2004). Global
u banisa ion has caused he loss o as amoun s
o habi a and caused majo modi ica ions o he
en i onmen al condi ions (Ta ainen, Ma kkola, &
S omme , 2003). Howe e , li le is known on
whe he o no hese changes a ec biodi e si y
in simila ways ac oss he globe (Niemela¨ e al.,
2000). In 1998, an in e na ional collabo a i e e o
o sea ch o gene alisa ions in u banisa ion im-
pac s on biodi e si y was ini ia ed. The p ojec ,
called Globene (Niemela¨ e al., 2000), examines
u ban–subu ban– u al g adien s, using a common
me hodology and a ge in e eb a e axon (g ound
bee les; Fam. Ca abidae) (Niemela¨ e al., 2000).
This axon was selec ed, because ca abids a e
especially use ul ecological indica o s o s udy
en i onmen al impac s, being sensi i e o habi a
modi ica ions and en i onmen al changes, abun-
dan and su icien ly a iable bo h axonomically
and ecologically (Lo¨ ei & Sunde land, 1996). The
esul s published so a ocussed mainly on he
changes o ca abid assemblage composi ion along
he g adien (Niemela¨ e al., 2002), wi h some
conside a ion o he e ec s o u banisa ion on body
size (Ishi ani, Ko ze, & Niemela¨, 2003;Magu a,
To´ hme´ e´sz, & Molna´ , 2004).
Va ia ion in body size has adi ionally been
desc ibed and analysed using he skewness o he
size dis ibu ion, o o he s a is ics de i ed om
he s a is ical momen s o he dis ibu ion (Sokal &
Rohl , 1995). Recen ly, he ocus has shi ed owa d
an emphasis on inequali y in size. Se e al measu es
o inequali y, de eloped o use in economics (Sen,
1973), ha e been used o analyse a ia ion in size
wi hin assemblages. These measu es use he Lo enz
cu e (Lo enz, 1905), whe e indi iduals a e anked
by size, and he cumula i e p opo ion o s udy
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T. Magu a e al.2
UNCORRECTED PROOF
objec s is plo ed agains he cumula i e p opo -
ion o hei o al size on he y-axis. I all
indi iduals a e equal in size, he Lo enz cu e is a
diagonal line, called he ‘‘line o equali y’’ (Fig. 1).
Inequali y causes he line o un below his line,
and he g ea e he inequali y among he s udy
objec s, he lowe he cu e uns below he line o
equali y. One app oach o quan i y his is he Gini
coe icien (Dixon, Weine , Mi chell-Olds, & Wood-
ley, 1987;Gini, 1912;Sen, 1973). Howe e , he Gini
coe icien is only ela ed o he size (a ea) and no
he shape o he cu e. Thus, he Gini coe icien
does no con ain all he in o ma ion in he Lo enz
cu e. Di e en Lo enz cu es can ha e he same
Gini coe icien (Damgaa d & Weine , 2000;Shum-
way & Koide, 1995;Weine & Solb ig, 1984).
The e o e, Damgaa d and Weine (2000), o cha -
ac e ise he shape o he Lo enz cu e, p oposed a
so-called ‘‘Lo enz asymme y coe icien ’’. This
coe icien cha ac e ises an impo an aspec o
he shape o a Lo enz cu e: i shows which size
classes con ibu e mos o he o al inequali y o
he assemblage (Damgaa d & Weine , 2000).
The new index was illus a ed by an example
om plan ecology, bu we seek o ex end i s use o
he analysis o size ela ionships in animal assem-
blages. In his s udy, we used pi all da a, collec ed
ac oss an u ban–subu ban– u al g adien o e 2
yea s, o analyse he body size inequali y o g ound
bee le (Ca abidae) assemblages. Using measu es
desc ibing asymme y and/o inequali y o body
size pa e n in ca abid assemblages, a hypo hesis,
sugges ed by Szyszko (1983),G ay (1989) and
Blake, Fos e , Ey e, and Lu (1994) was es ed.
Acco ding o his ‘‘dec easing body size hypo h-
esis’’, smalle ca abids should be ound in habi a s
wi h highe dis u bance le els han in hose wi h
lowe dis u bance. In ou case, he hypo hesis
p edic s ha he mean ca abid body size should
dec ease om he u al o he u ban a ea. We
ound ha he Lo enz asymme y index was he
mos powe ul me hod o de ec ends in size
along he g adien .
Ma e ial and me hods
Cha ac e ising he body size dis ibu ions
The ollowing measu es we e used o desc ibe
he asymme y and/o inequali y o body size
pa e n in ca abid assemblages.
(1) Skewness. The asymme y o a uni a ia e
con inuous dis ibu ion is commonly measu ed
by he classical skewness coe icien (Sokal &
Rohl , 1995), which is de ined as
g¼Sn
i¼1ðxi¯
xÞ3
ns3,
whe e nis he numbe o indi iduals, x
i
is he
body size o indi iduals i,¯
xis he mean body
size and sis he s anda d de ia ion o body size.
A symme ic dis ibu ion has ze o skewness, i.e.
g¼0. An asymme ic dis ibu ion wi h a longe
le ail has nega i e skewness (in ou case:
la ge indi iduals a e dominan ), while a posi i e
gindica es skewness o he igh (smalle
indi iduals a e dominan ).
(2) Medcouple. Since he skewness es ima o is
based on he i s h ee momen s o he da a
se , i is s ongly in luenced by he p esence o
ou lie s; hus, a obus measu e o skewness,
he medcouple (B ys, Hube , & S uy , 2004)
was also used. I has a 25% b eakdown alue and
a bounded in luence unc ion. The possible
alues o medcouple ange om 1 o1.
Fo no a ional con enience, he elemen s o he
da a se a e so ed such ha
x½1px½2ppx½n. Le med(X
n
) deno e he
median o he da a se X
n
, de ined as
medðXnÞ¼
ðx½n=2þx½n=2þ1Þ=2i nis e en;
x½nþ1=2i nis odd:
(
The medcouple is de ined as
MCn¼med hðx½i;x½jÞ;x½ipmedðXnÞpx½j
,
whe e he ke nel unc ion his de ined by
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popula ion C
popula ion B
popula ion
A
line o equali y
Cumula i e pe cen age o body size
Cumula i e
p
e cen a
g
e o indi iduals
Figu e 1. Lo enz cu es o h ee hypo he ical popula-
ions. All popula ions ha e he same Gini coe icien , bu
di e en Lo enz asymme y coe icien s. In he case o
he popula ion A, he Lo enz asymme y coe icien (S)is
la ge han one (S41), in he case o popula ion B, So1,
while size dis ibu ion in popula ion Cis symme ic,
leading o S¼1.
Body size inequali y 3
UNCORRECTED PROOF
hðx½i;x½jÞ¼ðx½imedðXnÞÞ ðmedðXnÞx½jÞ
x½ix½j
o all x½iax½j.B ys e al. (2004) also desc ibed
a as algo i hm o compu e he alue o he
medcouple.
(3) Gini coe icien . A adi ional g aphical ap-
p oach o measu e inequali y in size dis ibu ion
is he Lo enz cu e (Sen, 1973;Weine &
Solb ig, 1984). Indi iduals a e anked by size
and he cumula i e p opo ion o indi iduals is
plo ed agains he co esponding cumula i e
p opo ion o hei o al size. When all indi i-
duals a e o he same size, he Lo enz cu e is a
s aigh diagonal line, called he line o equal-
i y. I he e is any inequali y in size, he Lo enz
cu e uns below he line o equali y (Fig. 1).
The o al amoun o size inequali y can be
quan i ied by he Gini coe icien (Gini, 1912),
which is he a io be ween he a ea enclosed by
he line o equali y and he Lo enz cu e, and
he o al iangula a ea unde he line o
equali y. The Gini index o agg ega ion is based
on o de ed da a by inc easing body size as
ollows (Dixon e al., 1987):
G¼Pn
i¼1ð2in1Þx½i
n2¯
x,
whe e nis he numbe o indi iduals, x½iis he
o de ed body size o indi iduals iand ¯
xis he
mean body size. The Gini coe icien calcula ed
by he abo e equa ion should be mul iplied wi h
n=ðn1Þ o ob ain an unbiased es ima e (Glas-
se , 1962).
The Gini coe icien anges om a minimum
alue o ze o, i all indi iduals ha e he same
body size, o a maximum o one in a hypo he-
ical assemblage in which e e y indi idual
excep one has a size o ze o. Howe e , i has
been demons a ed (Damgaa d & Weine , 2000;
Shumway & Koide, 1995;Weine & Solb ig,
1984) ha di e en Lo enz cu es (assemblages
wi h di e en inequali y in size) can ha e he
same Gini coe icien (example on Fig. 1).
(4) Lo enz asymme y coe icien . To complemen
he abo e-men ioned Gini coe icien , Dam-
gaa d and Weine (2000) p oposed he Lo enz
asymme y coe icien , o quan i y he asym-
me y o he Lo enz cu e. The coe icien (S)
can be calcula ed om he o de ed body size
da a using he ollowing equa ions (Damgaa d &
Weine , 2000):
S¼Fð^
xÞþLð^
xÞ¼mþd
nþLmþdx0mþ1
Ln
,
whe e
d¼¯
xx0m
x0mþ1x0m
and ¯
xis he mean body size, mis he numbe o
indi iduals wi h a body size less han ¯
x,L
m
is he
cumula i e body size o indi iduals wi h a body
size less han ¯
x, and L
n
is he cumula i e body
size o all indi iduals.
When S¼1, he Lo enz cu e o he assemblage
is symme ic, while o he S alues ep esen
asymme ic Lo enz cu es. When S41, mos o
he inequali y wi hin he assemblage is due o he
la ges indi iduals, which disp opo iona ely con-
ibu es o he cumula i e body size (mass) o he
assemblage. When So1, he inequali y demon-
s a ed in he assemblage is due p ima ily o he
ela i ely la ge numbe o small indi iduals (Fig. 1;
Damgaa d & Weine , 2000).
S udy a ea and sampling me hods
G ound bee les we e s udied along an u ban–su-
bu ban– u al g adien in Deb ecen (Eas e n Hun-
ga y), he second la ges ci y o he coun y
(Magu a e al., 2004). The u ban, subu ban and
u al sampling a eas we e all pa o a once-
con inuous o es (Nagye d+
o Fo es Rese e) bo -
de ing he ci y. All a eas we e si ua ed in con in-
uous pa ches o old o es (4100 yea s) domina ed
by English oak (Que cus obu ). The ypical, na i e
o es associa ion o he sampling si es was
Con alla io-Que ce um. The c i e ion o dis in-
guishing sampling a eas (u ban, subu ban, u al)
was he a io o he buil -up a ea o he na u al
habi a s. The a ea o he buil -up en i onmen and
he na u al habi a s was measu ed by he A cView
GIS p og am using an ae ial pho og aph. In he
u ban a ea he buil -up a ea exceeded 60%, in he
subu ban a ea i was app oxima ely 30%, while in
he u al a ea he buil -up a ea was 0%. The o es
agmen s in he u ban a ea we e pa ks, whe e
se e al pa hs wi h asphal su aces had been
c ea ed and he sh ub laye was s ongly hinned.
In he subu ban a ea allen ees we e emo ed.
The e we e occasional, low-in ensi y o es y man-
agemen ope a ions in he u al si e. Dis ance
be ween he sampling a eas (u ban, subu ban,
u al) was a leas 1 km, as p esc ibed by he
gene al me hodology o he Globene p ojec
(Niemela¨ e al., 2000).
Fou si es, a leas 50 m om each o he (in o de
o achie e independence, see Digweed, Cu ie,
Ca´ camo, & Spence, 1995), we e selec ed wi hin
each sampling a ea. Ca abids we e collec ed a
each o he ou si es o he h ee sampling a eas
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using pi all aps o e wo ull ac i i y pe iods in
2001 and 2002. Ten aps we e placed andomly a
leas 10 m apa a each si e. This esul ed in a
o al o 120 aps sca e ed along he u ban– u al
g adien (3 a ea 4 si es 10 aps). Each pi all
ap was a leas 50 m om he nea es o es edge,
in o de o a oid edge e ec s (Molna´ , Magu a,
To´ hme´ e´sz, & Elek, 2001). Fu he in o ma ion on
ap design, placemen , mode o ope a ion as well
as he gene al desc ip ion o he collec ed assem-
blages a e gi en by Magu a e al. (2004). Fo he
p esen pape , we only used body size, collec ed
om he li e a u e (Hu
˚ ka, 1996), and he numbe
o indi iduals in he ca ch. Fo species whe e
minimum and maximum sizes we e gi en, we used
he mid- ange alue (see Table 1).
To es o di e ences in he measu es desc ibing
asymme y and/o inequali y o body size pa e n
in ca abid assemblages among he h ee sampling
a eas, epea ed measu es analyses o a iance
(ANOVA) we e pe o med (Sokal & Rohl , 1995).
When he ANOVA e ealed a signi ican di e ence
be ween he means, LSD (leas signi ican di e -
ence) es s we e pe o med o mul iple compa -
isons among means. The analyses we e ca ied ou
using he R package (R De elopmen Co e Team,
2004) and he SPSS-PC p og am.
Resul s
In bo h yea s, alues o skewness we e la ges in
he u ban a eas and smalles in he subu ban ones
indica ing ha mo e small indi iduals we e p esen
in he u ban a eas han in ei he o he o he wo
(Fig. 2A). The di e ences, howe e , we e no
s a is ically signi ican (Table 2). Simila esul s
we e ob ained wi h he obus measu e o skew-
ness, he medcouple. The alues we e highes in
he u ban a eas and lowes in he subu ban ones
(Fig. 2B). These di e ences we e conside ed
signi ican (Table 2). The Gini coe icien was
highes in he u ban a eas, and dec eased owa ds
he u al a eas, sugges ing ha body size inequali y
o ca abid assemblages was la ges in he u ban
pa ks, and dec eased along he u banisa ion g a-
dien (Fig. 2C). He e he yea ea men in e ac-
ion was signi ican , bu nei he o he componen
ac o s was (Table 2). The Lo enz coe icien s had
alues S41 o all si ua ions, indica ing he
impo ance o la ge indi iduals o he shape o
he Lo enz cu e. In u ban a eas, he alue was
e y close o S¼1 in bo h yea s. This is a
cha ac e is ic o a nea ly symme ic Lo enz cu e.
In bo h yea s, he u al a eas had he highes S
alues, and he subu ban a eas had in e media e
ones (Fig. 2D). The di e ences in he Lo enz
asymme y coe icien s among he s udied a eas
we e signi ican (Table 2). The alue o his
coe icien was signi ican ly highe in he u al
a eas compa ed o he subu ban and u ban a eas
(di e ences be ween hese wo las a eas we e no
s a is ically signi ican ). The e o e, he signi ican
di e ence in he shape o he Lo enz cu es was
caused p ima ily by a highe numbe o indi iduals
wi h la ge body size in he u al a ea s. he o he
wo a eas unde highe deg ee o u banisa ion.
Discussion
Analysing inequali y has a longe his o y in plan
han animal s udies. To desc ibe inequali y in plan
size, se e al s udies (C eed, Kain, & No on, 1998;
Di ommaso & Wa son, 1997;Zammi & Zedle ,
1993) used skewness de i ed om he s a is ical
momen s o he size dis ibu ion. Se e al o he
pape s used he Gini coe icien o measu e
inequali y in plan size o biomass (Hanley &
G o es, 2002;He, Ma, B own, & Lynch, 2005;Leiss
&Mu¨lle -Scha¨ e , 2001;Rams ad & Hes ma k, 2001;
Shumway & Koide, 1995;Wilson & Gu e i ch,
1995). Fo plan s, Damgaa d and Weine (2000)
calcula ed he Lo enz asymme y coe icien o
da a om Shumway and Koide (1995) o in e p e
he e ec o myco hizae and plan densi y on he
numbe o capsules p oduced by Abu ilon heo-
ph as i (Fam. Mal aceae) indi iduals. They we e
able o show ha he epo ed inequali y in he
numbe o capsules when he plan s con ained
myco hizae was caused by he inc eased impo -
ance o indi iduals wi h high capsule p oduc ion
(Damgaa d & Weine , 2000). This, howe e , emains
he only example o using he p oposed index.
Skewness is he only me hod used o e alua e
inequali y and/o asymme y in size dis ibu ion o
animal popula ions o assemblages (Gomez &
Espadale , 2000;G ego y, 2000;Knou , 2004;
Kozlowski & Gawelczyk, 2002;No o ny & Kindl-
mann, 1996;Poulin & Mo and, 1997). In he p esen
pape , we ex ended he ange o me hods applied
o analyse he inequali y o animal body size
dis ibu ion using wo o he pa ame e s ( he Gini
coe icien and he Lo enz asymme y coe icien )
and showed ha he Lo enz asymme y coe icien ,
S, is a powe ul me hod o s udies desc ibing and
in e p e ing a ia ions in body size.
Published s udies in he in e na ional Globene
p ojec cha ac e ised changes in he ca abid body
size dis ibu ion along he u ban–subu ban– u al
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Table 1. A lis o he ca abid species, hei body size, and he numbe o indi iduals collec ed in he u ban, subu ban
and u al sampling a eas du ing he wo s udy yea s nea Deb ecen, Eas e n Hunga y
Species Body size (mm) U ban Subu ban Ru al
Agonum lugens 9.0 2 0 0
Ama a an hobia 6.2 10 0 0
Ama a communis 6.5 9 0 0
Ama a consula is 8.3 0 1 2
Ama a con exio 7.7 113 26 47
Ama a amilia is 6.3 16 5 4
Ama a lucida 5.6 1 0 0
Ama a o a a 8.6 10 0 0
Ama a saphy ea 8.8 10 16 39
Ama a simila a 8.6 2 2 2
Anchomenus do salis 6.6 1 0 0
Anisodac ylus nemo i agus 8.9 52 0 0
Anisodac ylus signa us 11.8 1 1 0
Asaphidion la ipes 4.3 2 0 0
Badis e bulla us 5.2 11 1 0
Badis e lace osus 6.3 5 15 1
Badis e me idionalis 6.7 8 2 0
Bembidion lamp os 3.4 38 0 3
Cala hus e a us 9.5 2 0 1
Cala hus uscipes 11.1 26 0 3
Cala hus melanocephalus 7.1 1 0 0
Calosoma inquisi o 20.0 0 0 10
Ca abus con exus 17.0 1 107 124
Ca abus g anula us 19.0 6 1 6
Ca abus ull ichi 27.0 1 0 0
Ca abus iolaceus 28.0 75 78 237
Cli ina osso 5.9 3 0 0
Diach omus ge manus 8.4 1 0 0
Ha palus dis inguendus 9.5 0 1 0
Ha palus la us 9.1 14 1 24
Ha palus lu eico nis 7.1 5 20 1
Ha palus a dus 9.4 104 86 69
Ha palus xan hopus winkle i 7.1 21 10 3
Leis us e ugineus 6.8 0 0 1
Licinus dep essus 10.4 7 5 1
No iophilus bigu a us 4.9 2 0 0
No iophilus palus is 5.1 5 2 6
No iophilus u ipes 5.3 38 14 7
Ophonus ni idulus 9.6 1 2 42
Ophonus schaube ge ianus 8.8 0 0 1
Oxypselaphus obscu us 5.5 0 1 1
Panagaeus bipus ula us 7.2 7 5 0
Pla yde us u us 6.3 76 41 79
Poecilus cup eus 11.8 3 0 0
Poecilus e sicolo 10.5 1 0 0
Pseudoophonus g iseus 10.1 2 0 1
Pseudoophonus u ipes 13.1 10 26 19
P e os ichus an h acinus 11.2 5 3 0
P e os ichus mace 12.9 1 0 0
P e os ichus melana ius 15.7 58 3 1
P e os ichus melas 14.9 2 0 3
P e os ichus mino 7.6 0 1 0
P e os ichus nige 18.4 22 15 23
P e os ichus oblongopunc a us 11.5 117 454 1505
P e os ichus o oideus 7.1 1 0 0
P e os ichus s enuus 6.0 27 52 11
T. Magu a e al.6
UNCORRECTED PROOF
g adien using ei he he dis ibu ion among di e -
en , a bi a y size classes (Ala uikka, Ko ze, Ma -
einen, & Niemela¨, 2002;Ishi ani e al., 2003)o
he mean body size o he species weigh ed by hei
espec i e abundance (Gaublomme, Dhuy e e ,
Ve dyck, & Desende , 2005;Magu a e al., 2004;
Niemela¨ e al., 2002). In Finland, Ala uikka e al.
(2002) in es iga ing he changes o ca abid body
size ac oss an u banisa ion g adien concluded ha
medium- o la ge-sized ca abid indi iduals we e
mo e likely o be collec ed in he u al si es han in
u ban o es agmen s. In Japan, he e a e no
la ge and only ew medium-sized specialis species
in he u ban en i onmen , while many specimens o
medium-sized and some la ge-sized specialis spe-
cies occu in he subu ban and u al si es (Ishi ani
e al., 2003). Mean ca abid body size changed
signi ican ly om small alues in he u ban a ea o
la ge ones in bo h subu ban and u al a eas in
Bulga ia (Niemela¨ e al., 2002), Hunga y (Magu a e
al., 2004) and Belgium (Gaublomme e al., 2005).
The e was a ma ginally signi ican change in he
same di ec ion along he same g adien in Finland,
bu none in Canada (Niemela¨ e al., 2002).
Howe e , no only body size o he ca abid
assemblages may change ac oss an u banisa ion
g adien ; he e could be changes among di e en
popula ions o he same species. The body size o
Ca abus nemo alis dec eased signi ican ly om he
u al su oundings o Hambu g, Ge many, owa ds
he ci y cen e (Welle & Ganzho n, 2004).
The p esen s udy, using a mo e sophis ica ed
me hod ( he Lo enz asymme y coe icien ), no
only p o ed he exis ence o a signi ican change in
inequali y o ca abid body size ac oss he u ban–-
subu ban– u al g adien , bu indica ed ha his
di e ence was p ima ily due o an inc ease in he
con ibu ion o indi iduals wi h la ge body size in
he u al a ea. The mean body size o g ound
bee les also inc eased (Magu a e al., 2004), bu
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Table 1. (con inued )
Species Body size (mm) U ban Subu ban Ru al
S omis pumica us 7.5 1 15 27
Synuchus i alis 7.2 7 6 146
T echus quad is ia us 3.5 0 1 1
Species sequence is alphabe ical.
U ban Subu ban Ru al U ban Subu ban Ru al
U ban Subu ban Ru al U ban Subu ban Ru al
0
1
2
3
(D)
(C)
(B)
(A)
Skewness
-0.2
0.0
0.2
0.4
Robus skewness
2001
2002
0.0
0.1
0.2
0.3
Gini coe icien
0.0
0.5
1.0
1.5
Lo enz asymme y coe icien
Figu e 2. A e age alues (7S.E.) o he skewness (A), he obus skewness (B), he Gini coe icien (C) and he Lo enz
asymme y coe icien (D) o he u ban, subu ban and u al ca abid assemblages in he wo s udy yea s.
Body size inequali y 7
UNCORRECTED PROOF
his change can esul om a dec ease in he
impo ance o small species, om he inc ease in
medium-sized o la ge species, o a combina ion o
hese. By e alua ing he mean body size, we canno
dis inguish among hese possibili ies. The Lo enz
asymme y coe icien allowed us o demons a e
which o hese heo e ical possibili ies was espon-
sible o he obse ed e ec . The la ge ca abid
body size in he less dis u bed a ea ( u al a ea) and
he smalle body size in he mode a ely o highly
dis u bed a eas (subu ban and u ban a eas) could
be explained by he hypo hesis pos ula ed by
Szyszko (1983),G ay (1989) and Blake e al. (1994).
Szyszko (1983), s udying he egene a ion o pine
plan a ions a e clea -cu ing in Poland, sugges ed
and used he mean indi idual biomass (MIB) index.
This index is simply calcula ed as he a io o he
o al esh body mass o he ca ch in a ap, di ided
by he numbe o ca abid indi iduals caugh .
Szyszko (1983) showed ha as egene a ion in he
plan a ion p oceeds, he a e age alue o he MIB
index also inc eases. Mean body size is posi i ely
ela ed o body mass, and hus he conclusion is
ha he mean body size in ca abid assemblages will
also inc ease. G ay (1989) hypo hesised ha he
mean body size o species should dec ease om
undis u bed owa ds dis u bed habi a s. Ca abid
assemblages o di e en ly managed g asslands
ga e suppo o his hypo hesis (Blake e al.,
1994). Highly dis u bed a eas suppo ca abid
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Table 2. The esul s o epea ed-measu es ANOVA o he alues desc ibing asymme y and/o inequali y o body size
pa e n in ca abid assemblages
Sou ce SS d MS FpLSD es
Skewness
Tes s o wi hin-subjec s con as s
Yea 0.001 1 0.001 0.008 0.931
Yea A ea 0.306 2 0.153 0.890 0.444
E o 1.547 9 0.172
Tes s o be ween-subjec s e ec s
A ea 2.473 2 1.237 1.235 0.336
E o 9.011 9 1.001
Robus skewness
Tes s o wi hin-subjec s con as s
Yea 0.058 1 0.058 1.099 0.322
Yea A ea 0.020 2 0.010 0.192 0.828
E o 0.479 9 0.053
Tes s o be ween-subjec s e ec s
A ea 0.424 2 0.212 3.868 0.061 U4S
E o 0.493 9 0.055
Gini coe icien
Tes s o wi hin-subjec s con as s
Yea 0.0001 1 0.0001 0.142 0.715
Yea A ea 0.008 2 0.004 5.073 0.033
E o 0.007 9 0.0007
Tes s o be ween-subjec s e ec s
A ea 0.014 2 0.007 1.974 0.195
E o 0.031 9 0.003
Lo enz asymme y coe icien
Tes s o wi hin-subjec s con as s
Yea 0.003 1 0.003 0.044 0.839
Yea A ea 0.058 2 0.029 0.469 0.640
E o 0.558 9 0.062
Tes s o be ween-subjec s e ec s
A ea 0.932 2 0.466 7.315 0.013 U¼SoR
E o 0.573 9 0.064
Yea ¼ he e ec o s udy yea (2001 and 2002), A ea ¼ he u ban, subu ban and u al sampling a eas. Resul s o he LSD es indica e
which a ea(s) di e (s) signi ican ly (po0:05) om he o he s; o example U¼SoRindica es ha he measu ed alue was
signi ican ly highe in he u al a ea han in he u ban and subu ban a ea ( hese wo a eas, howe e , we e no di e en ).
T. Magu a e al.8
UNCORRECTED PROOF
assemblages wi h species o smalle a e age body
size han do less dis u bed si es (Blake e al., 1994;
G andchamp, Niemela¨, & Ko ze, 2000;Holliday,
1991;Magu a, Elek, & To´ hme´ e´sz, 2002;Ribe a,
Dole´dec, Downie, & Fos e , 2001;S
ˇus ek, 1987).
The causes o his can be mani old. Ca abids ha e
g ound-li ing la ae ha a e weakly chi inised,
limi ed in mobili y, and hus mo e sensi i e o
changing condi ions han adul s (Lo¨ ei & Sunde -
land, 1996). Dis u bance will equen ly c ea e
un a ou able condi ions o g ound bee le adul s as
well as la ae, when hei densi ies dec ease
(Tho bek & Bilde, 2004) and species may become
locally ex inc . Small-sized ca abid species may
su e less mo ali y du ing such dis u bance
e en s. Thei densi ies a e also usually highe han
ha o la ge-sized species (Lu , 2002), so hey
ha e a lowe p obabili y o local ex inc ion. Small
species a e mo e o en winged han a e la ge-sized
species (Ribe a e al., 2001). Consequen ly, small
species a e mo e agile han la ge species and can
colonise dis u bed and uns able a eas mo e easily
(Thiele, 1977). Smalle species may also need
ewe esou ces and/o may de elop as e han
la ge species (Pe e s, 1983). In ca abids, la ge
species ha e longe la al pe iods, making hem
mo e ulne able o dis u bance e en s (Ko ze &
O’Ha a, 2003). Small species can use he small
‘‘windows o sui abili y’’ o su i e in he dis u bed
habi a . Lo¨ ei and Sunde land (1996) also call
a en ion o he impo ance o la ae o explain
ends in adul s.
Along he s udied u banisa ion g adien , he
deg ee o dis u bance is highe in he u ban (pa ed
pa hs, hinned sh ub laye , in ensi e landscape
managemen ) and in he subu ban a ea (manage-
men o mode a e in ensi y, e.g. allen ees a e
emo ed) han in he u al a ea ( a e occasions o
in e en ion, low in ensi y managemen ). Dis u -
bance caused by u banisa ion appea s o elimina e
a ou able mic osi es o o es species wi h la ge
body size and c ea e al e ed, ela i ely homoge-
neous mic o-habi a s in aded by small-sized spe-
cies capable o lying. All hese habi a al e a ions
accompanied by u banisa ion con ibu ed o he
obse ed a ia ion in ca abid body size ac oss he
u ban–subu ban– u al g adien .
Using he Lo enz asymme y coe icien (Dam-
gaa d & Weine , 2000), we we e able o mo e
comple ely analyse he size dis ibu ions o he
g ound bee le assemblages along he u banisa ion
g adien . This index has p o en o be mo e powe -
ul han mo e adi ional me hods such as skew-
ness, obus skewness (medcouple), o he Gini
coe icien . The biological in e p e a ion o he
index is no p oblema ic, and we sugges ha i is a
use ul ool o u u e s udies o size/biomass
dis ibu ion in animal assemblages.
Acknowledgemen s
The Globene s udy in Hunga y was suppo ed by
he Ho oba´gy Na ional Pa k Di ec o a e. T. Magu a
is a Bolyai Resea ch Fellow o he Hunga ian
Academy o Sciences. We a e especially g a e ul
o Ti ada Molna´ o ield and labo a o y assis-
ance. We hank wo anonymous e iewe s o hei
help ul commen s on he manusc ip .
Re e ences
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Insec Conse a ion,6, 195–206.
Blake, S., Fos e , G. N., Ey e, M. D., & Lu , M. L. (1994).
E ec s o habi a ype and g assland managemen
p ac ices on he body size dis ibu ion o ca abid
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