ECOTROPICOS, Vol. 3 (2): 77-86.
Socicdad Vcnczolana de Ecología
1990
PLANT RESPONSE TO HERBIVORY:
TWO EXAMPLES FROM THE NEOTROPICS
RESPUESTA DE LAS PLANTAS ALA
HERBIVORIA
DOS EJEMPLOS DEL NEOTRÓPICO
G
IDepartment
Wilson
of Biological
2Present Address:
Biologicas,
Fernandesl.2
Sciences,
Sérvio
P.
5640, Northern
Arizona
86011 -U.S.A.
de Biologia
Geral, Caixa Postal
Departamento
Universidade
and
Federal
Box
de Minas
Gerais,
30.161
-Belo
Ribeiro2
University,
2486,
Flagstaff,
Instituto
Horizonte.
AZ
de Ciencias
MG
-BRAZIL
ABSTRACT
The responses of two neotropical
comparisolls
stem gallillg
illdicated
tcphritid
Damagc-rcsponse
Oll frost affected
by a buprestid
plant
species to herbivory
and frost
were studied.
Within-plant
that Bricke/lia
pinnifolia
(Compositae)
brallches rcspollded
to herbivory
by a
specics and frost by producillg
largcr alld morc shoots thall ullaffected brallches.
(mcasured in tcrms of number of shoots alld shoot lcllgth) was sigllificantly
higher
thall Oll gallcd bra11Ches, which was higher tlla11 Oll ullaffected brallches. Herbivory
illsect Oll tlle tlower
stalk of Paepalanthus
speciosus (Eriocaulaceae)
sigllificalltly
il1creased
productioll
of compomld um\)els alld il1dividual illflorcsccl1ces.
Howcver,
fcwer il1dividual il1florcscellces
dcvclopcd to fruit stagc Oll eatcll plallts comparcd to lU1eatel1 plal1ts. No clear illfluel1ce of herbivorc
attack was observcd Ol1 host plallt fillal hcight, or Oll overa1l COmpolU1d umbcl diameter.
A secol1d
wavc of hcrbivory
fo1lowed aftcr plalltS respol1ded to the first ol1e. III tl1Ís secol1d wavc, 72% of tlle
compoul1d umbels were dcstroyed and l1O furthcr plallt respol1Se was observcd. It appears tllat resourcc
mal1ipulation
by tlle hcrbivore
may bc involved
in tl1Ís case. The adaptivc l1atllre of plallt respOl1SC
to damages caused by frost alld hcrbivorv
is discusscd.
"
KEY WORDS: Brickellia pinnifolia, herbi..'ory, Neolropics, PaepalaJI/husspeciosus, planl compcnsalory responses.
RESUMEN
Sc cstudi6
cl cfecto
de los herbívoros
y
Ia fornlaci6n
de cscarcha
en dos cspccics
de plantas
neotropicalcs.
La cornparaci6n entre Ias plantas Í1ldic6 que Ias rantas de Brickellia
pinnifolia
rcsponden
tanto a Ia forntaci6n
de escarcha como a Ia herbivorfa
por parte de un tefritfdo
quc ind~lce agallas
cn cl tallo, prod~lcicndo
rctofios nlás largos y más numerosos quc cn Ias ramas no afcctadas. La
respuesta al dafio (mcdida cn términos de número y longitud dc retofios) fué significativamente
mayor
en Ias ramas afectadas por Ia forlnaci6n
de escarcha que en Ias que teniall agallas, Ias cuales a su
vez sufricron
en el tallo
ll1l dafio mayor
de Ias flores
que aquellas que no fueron
de Paepalanthus
speciosus
atacadas. EI impacto
(Eriocaulaceae),
de un insecto bupréstido
increment6
significativamente
Ia
produci6n de umbclas e Í11florescellCijs i1ldividuales. Sin embargo, en estas plantas muy pocas i1lflorcscencias
individualcs
Ilcgaron a fruto cn (omparaci6n
con Ias plantas que no sufrieron
este ataque. No se
observ6 una clara influencia
dei ataque deI herbívoro
sobre el peso final de Ia olanta ni sohre f'.1
FERNANDES
AND
RIBEIRO
diámetro completo de Ia umbela. Una segunda ola de herbívoros
Ie sigue a Ia primera \Ula vez que
Ias plantas hatl respondido al ataque. En este segwldo ataque, 72% de Ias umbelas fueron destmfdas
y no se observaron nlás respuestas de Ia planta. AI parecer, en éste ataque existe \Ula nlal1Ípulación
deI recurso por parte de Ios herbfvoros.
Se discute Ia naturaleza adaptativa de Ias plantas a datios
ocasionados
PALABRAS
por
CLA VE:
Ia fornlación
Brickellia
de escarcha
pinnifolia,
herbivoría,
y por
Neotrópico,
INTRODUCTION
After examining numerous studies on
the beneficial effects of herbivory , Belsky
(1986) concluded that there is as yet no
convin.cing
evidence
that herbivory
is
beneficial to plants under natural conditions.
However,
Paige and Whitham
(1987)
experimenta1ly
demonstrated
that under
natural fie1d conditions plants can benefit
from being eaten. They found that after
the removal of 95% or more of the above
ground biomass of the biennial scarlet gilia,
lpomopsis aggregata, seed production and
seedling survival were 2.8 times greater
than that of uneaten controls. Unbrowsed
p]ants produced only single inflorescences,
whereas browsed p]ants produced multip]e
inf]orescences.
Daspite
Paige
and
Whitham's (1987) clear demonstrations of
the
beneficial
impact
of
browsing
herbivores on p]ants, more studies on the
effects of herbivores on p]ants in both
temperate and tropical regions are needed.
We present preliminary
evidence on how
two tropical p]ant species respond to insect
herbi vory .The
morphology of Brickellia
pinnifolia
A.
Gray
(Cornpositae)
is
modified by gal1 formers and frost. A
tephritid
insect ga]] on stems of B.
pinnifolia
is very common in Serra do
Cip6, MG, Brazi]. Gal1ed branches exhibit
modifled
morphology
b~cause
gall
formation interferes with normal growth
78
Ia herbivoría.
Paepalanrhus
speciosus,
respllestas
compensatorias
de plantas.
patterns. Galled branches resembled ' 'witchbrooms' , , with many shoots growing
from
the proximal and distal portions of the gall.
Gall formation
is frequently
cited as a
factor interfering
with host plant
p1pmorphologyand
fitness (e.g., Dennill 1985,
1988; Fernandes
1987 and references
therein) .Frost also damages terminal shoots
and a1ters branch morphology,
causing
branches to depart from
their normal
growth pattern, and the death of terminal
shoots.
Frost
affected
branches
also
resembled "witch-brooms",
but only the
terminal
portion
of the branches were
affected .
We also censused a second plant
species,
the
monocot
Paepalanthus
spedosus (Bong) Kolin (Eriocaulaceae), that
is attacked by an unidentified
species of
buprestid beetle. Adults of the beetle chew
the single flower stalk produced by the
host plant; they chew through it until the
terminal compound umbel falls off the
plant. Casual field observations suggested
that
chewed
plants
produced
more
compound
umbels,
and
individual
inflorescences than uncheweli plants (Fig.
1). It appears that P. Spil-'vSUS is an annual
(T .S.M. Grandi, personal communication).
In the B. pinnifolia
system we asked: 1)
Does herbivory and/or frost influence shoot
production
and shoot length? In the P .
speciosus system we asked the following
questions: 1) Does herbivory influence plant
PLANT
RESPONSE TO DAMAGE
PRIMARY
UNATTACKED
FIGURE
1. Schematic
ATTACKED
represelltatioll
of P.
speciosus
plants.
OllIy
olle
ternúllaI
COmplU1d lImbeI
is
produced by lU1eatell plaIltS. Eatell Í1ldividllalS produce n1aIly more tern1ÍnaI compmld umbeIs. Nevertheless,
these are SigllificaIltly
smallet thall the ternúllaI compomld
lImbeIs of U11eaten plaIltS.
final height? 2) Do eaten plants produce
more compound
umbels
than uneaten
plants? 3) What is the effect of herbivory
on inflorescence quality?
MATERIALS
The
Serra ào
which is
poor soil
Silveira
ECOTROPICOS
AND
METHODS
plants we studied are located in
Cip6, Minas Gerais State, Brazil,
characterized by rocky, nutrientand low-nutrient status plants (see
1908, Hoene 1927. Hutchinson
Vol.
3
(2).
1990
1943, 1945, Joly 1970, Goodland and Ferri
1979).
We sampled B. pinnifolia
in
February 1988, and P. spedosus in April
1988. Flower buds in the distal portion
of the branches of B. pinnifolia
break
dormancy after a vegetative growth phase,
thus starting the flowering season. Many
flower heads are produced at the terminal
portion of the branches. Many dormant
buds are also present along the branches.
These buds may uecome active after the
dominant buds are damaied or deJtroyed,
"n
FERNANDES
AND
We counted the number of new shoots and
measured the lengtll
of galled,
frost
affected, and uneaten branches. After a
veget.'lti ve rosette stage, P. speciosus
produces a leafy stalk terminating with one
large compound umbel (Fig. 1). Thus, a
compound umbel, and several individual
inflorescences are produced. Dormant buds
are present along the plant's leafy stalk.
There is no study available on the floral
biology of P. speciosus (A.M.
Giulietti,
personal communication).
We measured
plant final height, number of primary
inflorescences,
number of flower heads,
quality of inflorescences (here measured as
develQped or atrophied) , and inflorescence
diameter, as the plant variables affected
by tl1e flower stalk herbivore.
Because the number of shoots and
their
lengths
are
not
independent
12
ffi
a)
~
=>
Z
fO
O
:I:
(I)
RIBEIRO
measurements, we multiplied the number
of shoots by their lel1gths for each
treatment in order to have what we called
a '.damage response index".
A nonparametric test to analyze the B. pinnifolia
data was used because of unequr.l variances
among the treatments (Quade test, Conover
1980, Zar 1984).
RESULTS
Frffit
Frost
affected
produced
1onger
and
significantly
shoots
galled
more
branches
shoots
than unaffected
and
branches
of
B. pinnifo1ia
(Quade
test, p < 0.0001,
Fig.
2a). Frost affected
(N = 41) and
ga11ed branches
(N
average
(SE
of
9.37
=
41)
produced
..:t 0.62),
and
an
5.56
12
A
Ê
3
9
:I:
f"
i..
6
al1d gall effects 011R. pinnifolia
9
Z
6
O
3
w
-l
f-
O
:I:
{1)
3
o
FROST
GALL
FROST
UNDAMAGED
GAll
DAMAGED
DAMAGED
FIGURE
2. Brickelia
pinnifolia
response to frost, alld herbivory
by a tcphritid
A) Shoot nlmJbcr prodllced by frost affected, galled, alld \JIlaffected B. jJinnifolja
UNDAMAGED
stem galling inscct.
stenlS. Therc wcrc
statistically
significant differenccs i;l thc numbcr of shoots produccd by frost, alld gallcd ~tcms comparcd
with unaffcctcd stcms (Qllade tcst, F280 = 3.15, p < 0.0001). B) Lcilgth of shoots produccd by frost
affcctcd,
galled,
betwccn
alI
80
and unaffcctcd
trcatmcnt
mcalls
brallclies
(see Table
of B. pinnifolia.
1 alld
tcxt
for
Thcre wcre statistically
results).
significallt
differences
PLANT
RESPONSE TO DAMAGE
(SE .:t 0.24) shoots, respectively. On the
other hand, unaffected branches produced
an average of only 3.15 (SE .:t 0.15)
shoots. Branches hit by frost, and by the
gall herbivore produced the longest shoots.
Frost affected branches produced shoots
averaging 8.72 cm (SE .:t 0.36 cm), and
galled branches produced shoots averaging
T ABLE
1. Multiplc
9.62 cm (SE ..::t 0.63); while unaffected
branches produced shoots averaging 6.5 cm
(SE ..::t 0.23, N = 41, Fig. 2b). Multiple
comparisons
of treatment
means (see
Conover 1980: 297) indicated significant
differences
between
all
treatments
(Table
1).
compariso11S of treatme11t mca11s amo11g effects
CO110VCr 1980: 297). The treatmc11ts were CO11Sidcreddiffere11t from
thcir sums I s; -s; I cxcccded:
2b (Ai
ISj
>
-Sil
t
treatments
were
TREATMENT
significantly
differcnt
COMPARISON
among
DIFFERENCE
-BJI/2
-1)
them.
IS,
-S,
1534.0
I s,uJaITecled
Sfr~1
I SlUlaffcclcd
SgolJ..1I
I Sfr~1
(scc
a12
(b -1)(k
AlI
of damage 011 B. pinnifolia
each other if the differc11cc betwee11
911.0
623.0
-S.allcd
~
Hcrbivore
Effects
Plant
height
by
the
>
0.05,
final
011 P.
speciosus
was not
umbel
stalk
herbivore
Fig.
3a).
Eaten
influenced
(Anova,
plants
p
had
an
average height of 113.33 cm (SE .:t 6.33
cm, N = 15), and uneaten plants averaged
129.21
cm
(SE
.:t
8.28,
Eaten individl1als
more
compound
individuais
produced
umbels
(Anova,
N
p <
=
24).
significantly
than
0.0001,
uneaten
Fig.
and 3b).
Eaten
individual
produced
average of 5.8 (SE .:t 1.32,
N =
compound
ECOTROPICOS
umbels,
Vol.
while
3 (2).
1990
uneaten
1,
an
15)
produced
only one compound umbel per plmlt (N
= 24). In addition, eaten plants produced
significantly more individual inf1orescences
than uneaten plants (Anova, p < 0.05,
Fig. 3c). Eaten plants produced an average
of 178.0 (SE .:t. 28.3, N= 15) individual
inf1orescences while uneaten plants only
produced 128.2 (SE .:t. 14.6, N=
24)
individual inflorescences. Both compound
umbels
and
individual
inf1orescences
produced by eaten plants were significantly
smaller than those produced by uneaten
plants. However,
the overall size (total
diameter) of the compound umbel of eaten
RI
FERNANOES
ANO
RIBEIRO
6
140
Ê
2
1-
:1:
~
w
:1:
1Z
<
--1
o.
>a:
<
~
a:
!1-
70
O'
Z
O-L-UNATTACK
200
o
z
o
()
w
cn
O'
Z
3
~
o
ATTACK
cn
w
()
z
w
u
cn
w
a:
o
..J
u.
~
{1)
w
u
z
w
u
{1)
w
cr
o
..J
u.
c
Ê
2
a:
.,-L.
w
1W
~
~
o
..J
100
I
u.
z
o
ATTACK
ATTACK
UNATTACK
ATTACK
UNATTACK
50
25
o
ÚNATTACK
100
~
u.
~
~
d
z
o
(.)
w
(/)
2
c
w
0.
o
..J
w
>
w
c
50
o
ATTACK
FIGURE
3. Paepalanthus
speciosus
responsc
UNATTACK
to a buprcstid
bcctlc
hcrbivory
.A)
Final
plant
hcight
was not influenccd
by the inflorcscence
stalk herbivore (Anova,
FI.37= 1.87, p > 0.05). B) Eaten
individuaIs
produced significanlly
more primary
infloresce11ces thaIl lmeate11 i11dividuals (A11Ova, F 137
= 21.59, p < 0.0001). C) Eatcn individuais
produced sig1lifica11tly morc seco1ldary ililloresce1lces thá11
\mcate1l i1ldividuals
(A1lova, F 1.37 = 2.96, p < 0.05). D) It1floresce1lce size of eate1l iI}dividuals
was
1lot sig1lificantly
differc1lt from lilat of U1leate1l i1ldividuals
(A1lova, F t.37 = 0.099, p > 0.05). E)
Sig1lificanlly
fcwcr scco11dary inflorcsce11ces devclol)Cd O1l eatc11 plants
(A11Ova, F 1.37 = 9.60, p < 0.002). (scc tcxt for rcsults).
82
compared
to uneate1l plants
PLANT
RESPONSE TO DAMAGE
plants was not significantly
different from
that of uneaten individuaIs [Anova, p >
0.33, Fig. 3d; eaten 39.60 cm diameter
(SE ..t 2.34, N= 15), uneaten 36.58 cm
diameter (SE ..t 1.91, N= 24)].
Although significantly more compound
umbels and individllal
inflorescences were
produced on eaten plants compared to
uneaten
plants
(Figs.
3b and 3c),
significantly
fewer flowers on individual
inflorescences developed to fruit stage on
eaten plants compared with uneaten plants
(Anova, p < 0.002, Fig. 3e). Eighty five
percent of the flowers
on individual
inflorescences of eaten plants developed
com~letely to the fruit stage (85.44%, SE
..t 0.05, N = 15) as opposed to 97%
that developed completely to the next stage
on uneaten plants (97.34%, SE ..t 0.01%,
N = 24).
Failure to develop was due primarily
to atrophy of the irldividual inflorescences.
Undeveloped
(atrophied)
individual
inflorescences were smaller and blackish
compared to developed ones.
Of the fifteen plal1ts that were attacked
by the flower herbivore, 5 (33%) suffered
a second attack which was responsible for
the loss of 72 % o~ the newly produced
compound
umbels.
DISCUSSION
Brickellia
pinnifolia
branches
responded to herbivory by prodllcing ]arger
and more shoots than unaffected branches.
FlIrthermore,
the number of shoots, and
shoot ]ength were significantly
higher on
frost affected than on gal1ed branches which
were higher than on unaffected branches.
The higher number of shoots, 8S wel1 as
]onger shoots, prodllced by l'rost affected
branches compared with gal1ed branches
ECOTROPICOS
Vol.
3 (2).
1990
is intriguing.
There are at least four
alternative
but not mutually
exclusive
hypotheses that may be responsible for this
plant
response pattern.
The first hypothesis predicts that apic.1l
buds grow more vigorously
than lateral
buds, and plant energy is canalized to the
apical meristems thus enabling more buds
to break dormancy (see Longman 1978,
Tomlinson
1978) .In
fact, frost affected
only apical meristems whereas the stem
gall tephritid destroyed only lateral buds.
The second hypothesis predicts that
fewer buds were damaged by frost than
by the gall tephritid, thus resulting in the
higher numbers and larger shoots found
on frost-affected branches compared with
galled branches. Only terminal buds were
hit by frost whereas galling
may had
affected more buds that were perhaps less
active and less dominant lateral buds, thus
reflecting in fewer, and smaller branches .
The third hypothesis predicts that the
gall competes for energy with the adjacent
buds thus making
them shorter,
and
suppressing bud break in some dormant
buds. Insect galls induce dramatic metabolic
changes in their host plants during gall
formation and growth (e.g. Rohfritisch and
Shorthouse
1982, Fernandes 1986 and
references therein) that could be associated
with the B. pinnifolia's
observed response
patterns. Furthermore,
galls are nutrient
sinks within host plants (see Jankiewicz
et al. 1970, Stinner and Abrahamson
1979), so that portion of the nutrients
available for plant growth is diverted to
gall maintenance. On the other hand, in
frost damaged branches, all the energy
would be directed to the growth of new
shoots because a branche would not have
part of its energy diverted to a different
structure.
83
FERNANOES
The fourth
hypothesis predicts that
frost
response is more prcdictable than
gall response and that plants have evolved
to respond to frost damage with longer
and more numerous
shoots. Frost is a
phenomenon of high predictability
in the
high elevations of the Serra do Cip6 that
affects alI B. pinnifolia's
unhardened buds,
whereas galling is phenomenon dependent
on highly variable factors such as host
plant defense, host plant quality, herbivore
abundance, and herbivore
host finding
behavior, for instance. Frost would then
be more predictable both in space and time
than galling. However, more work is called
to u~ravel the mechanisms and processes
behind the trends fol1l1d.
Each stem of B. pinnifolia termil1ates
in many flower heads. We specl1late that
more bral1chil1g wiII Iead to more flowers
al1d frui ts being prodl1ced. We do not
kl1ow, however, how mal1y viable seeds
the new bral1ches prodl1ce, al1d whether
the replacemel1t of damaged shoots affects
timil1g of seec dispersaI al1d seedlil1g
establishment.
Another
important
ul1al1swered question is how tllis extra
expel1ditl1re of reSOl1r<;esaffects survivorship
and Iife time seed ~rodl1ction.
the
Herbivory
flower
by a buprestid
stalk
of
P.
beetle on
speciosus
ANO
RIBEIRO
attack
may also have altered
among
flowers
within
inflorescences.
flowering
or are more
likely
Schemske
or
diameter.
1977,
see
compoul1d
attraction
m~y
Campbell
19E5,
1985).
They
in annuals
do Cip6
cons.pecific,
pollil1ator
The
production
individual
Rathcke
1974).
bc
al1d
display
generar,
al1d size
habitats
far
is not clear .A
vallle
might
of
be
plal1ts
from
a
to fil1d for
thc
of
compcl1satory
compound
innorescel1ces
nowcr
where
away
and thll5 hard
of
Mottcl1
sllch as tlle Serra
the adaptive
species.
sigl1ifical1ce
(c.g.
importal1t
there is a marked
il1 tropical
for
adaptive
Campbcll
and il1 habitats
inflorescel1ce
il1
1988,
may be evcl1 more
season. Furthermore,
amplified
19BO, Wyatt
al1d compctitiol1
also
il1 which
Willson
al1d Spciscr
and
display
of
umbel
(c.g.
Zimmcrman
Willsol1
pollil1ators
innuel1ce
sizc is an important
Schimid-Hempcl
Inflorescel1ce
(e.g.
011 host plal1t fil1al
011 overall
for pollil1ator
affectcd
condition
clear
Innorescel1cc
and Price
are,
delay
produced
to be adversely
was observed
height,
but
newly
or weathcr
1977) .No
herbivory
1982,
may
tl1at the
on eaten plaJltS are not p)llinated
by temperattue
factor
individual
Herbivory
such
flowers
the sex ratios
umbcls
in
secol1d wave
P.
nl1d
.çp(~Ci().Çll.Ç
of hcrbivory
significal1tly
increased
prodl1ction
of follows
after plal1ts respond to the first
compound
l1mbels
and
individual
herbivore
attack. 111 this sccond wavc of
inflorescences. However, fe\Ver flowers in attack 72% of the compound umbcls wcre
the il1dividl1al il1florescel1ces developed into destroyed and no plal1t growth
rcsponse
frl1its on eaten plants compared
with
was observed. There arc at Icast two, not
ul1eatel1 plal1ts.
The
"atrophy"
al1d l1ecessarily mutllally cxclllsive, mechal1isms
col1seql1ent frl1it faiIl1re observed on eaten or hypotheses that may be involvcd hcre.
il1dividl1al inflorescences migh( be the result The first hypothesis
is OI1C of mcristcm
of herbivory.
Flowers il1 thís family are 1imit.'ltion il1 which axillary
bllds localcd
gel1eralIy unisexual al1d male al1d female in the co:npoul1d umbcl stalk had alrcady
flowers occur il1 the same Ilower heads developcd
into
sccondary
il1norcsccl1ccs
(Dahlgreel1 et al. 1985) al1d herbivore
prior
to the first wave of attack.
ll1e
84
PLANT
RESPONSE TO DAMAGE
second hypothesis
is one of resource
limitation
in which the plant could not
respond to the second attack because there
were no resources left. These p]ants live
in nutrient-poor soil habitats. Thus, p]ants
may be constrained in their response to
herbivory
after
the "limited"
energy
backtlp supply is used. The differentia]
response of nutrient-stressed and hea]thy
p]ants to herbivory
remains to be ful]y
eva]uated. In simi]af systems, Paige and
Whitham (1987), and Hendrix (1979, 1984)
did not observe a second wave of attack
by the herbivore on their sttldy p]ants. A
second wave of attack by the herbivore
wou]d jeop~rdized the compensatory growth
response of the host p]ant. The argument
that p]ant overcompensation is adaptive to
the plant (see Paige and Whitham 1987)
was only partiaI]y supportcd in this study.
An herbivore's view of these findings
indicates that the P. speciosus flower
herbivore
may
be
manipu]ating
its
resources. The plant response to the first
attack wou]d cause many more resources
to be produced which wou]d then be used
by the herbivore.
If the herbivore ais
specialist on this p]ant specjes and/or this
plant fami]y,
this strateg.Y would
be
adaplive for the herbivore.
In fact, we
observed similar damage on other c]ose]y
related Paepalanthus species. A resource
manipulation strategy wou]d be important
to the herbivore for adjusting pheno]ogica]ly
to P. speciosus if p]ant popu]ations present
assynchronous flowering
seasons in the
a]titudina] gradient of Serra do Cip6, andl
.or Paepalanthus species present different
tlowering phenologies.
studies
are
ca]]ed
Nevcrthe]ess,
to
unraveI
mechanisms and processes invo]ved
more
the
in this
In summary, plants may respond to
abiotic or frost damage, and herbivory in
many different ways. Many historic and
ecological
factors may influence
these
responses, such as the type of damage,
plant phenology, plant nutritional
status,
plant phylogenetic constraints, as well as
the kind of interactions plants have with
their
herbivores
(see Maschinsky
&
Whitham
1989, Whitham
et al. 1990).
Genera]izations
about whether a p]ant's
compensatory responses to herbivory,
as
well as physical damage, are adaptive for
the plant can be made only after the who]e
spectrum of responses of both plant and
herbivore
are fully explored and more
studies are performed in both tropical and
temperate
ACKNOWLEnGMENTS
We are grateful
to the following
persons for their comments on earlier drafts
of this manuscript and/or assistance: S.
Suter, T.G. Whitham, C. Ghering, H.R.
Pimenta,
J.
Romero-Napoles,
J.
Maschinski, and two anonymous reviewers.
We thank Giulietti
for identifying
the
plants. L.A.
Renn6 and U.G.
Castro
(ICB -Universidade
Federal de Minas
Gerais) provided the field facilities which
are greatly acknowledged.
A Sigma Xi
grants-in-Aid
and a scholarship
of the
Conselho Nacional de Pesquisas (CNPq)
(process N 200.747 /84-3-Z0)
to GWF is
also acknowledged.
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