MORPHOLOGICAL TRAITS OF COMMON TOAD Bufo bufo ...

NATURA MONTENEGRINA, PODGORICA, 6:101-109
MORPHOLOGICAL TRAITS OF COMMON TOAD Bufo bufo (Bufonidae) FROM
BIOGRADSKO LAKE
Natalija Č A Đ ENOVIĆ ¹, Tanja V U K O V ²
¹ Natural History Museum of Montenegro, Podgorica, Crna Gora, E-mail: lazo@cg.yu
² Institute for Biological Research “Siniša Stanković”, Beograd, Srbija
Key words:
Bufo bufo,
morphometric,
qualitative characters,
differences between
the sexes.
SYNOPSIS
In this paper we have presented the results of the
analysis of morphological traits of Common Toad Bufo bufo
population, from Biogradsko Lake. On the samples taken
from this locality univariant and multivariant statistical
analyses have been performed. A large number of
morphometric and qualitative characters have been done for
the first time. For morphometric characters basic parameters
of descriptive statistics have been calculated, and for
qualitative characters three qualitative traits with three
conditions at four body regions of Common Toad separately
by sexes, have been treated. As for the morphometric
characters it has been established that there is a significant
statistical difference between the sexes.
Ključne riječi:
Bufo bufo,
morfometrijski,
kvalitativni karakteri,
razlike među
polovima.
SINOPSIS
MORFOLOŠKE KARAKTERISTIKE OBIČNE KRASTAVE ŽABE
BUFO BUFO (BUFONIDAE) SA BIOGRADSKOG JEZERA
U ovom radu su prikazani rezultati analize morfoloških
odlika populacije krastave žabe Bufo bufo, sa Biogradskog
jezera. Na uzorcima uzetim sa ovog lokaliteta urađene su
univarijantne i multivarijantne statističke analize. Po prvi put
je obrađen veliki broj morfometrijskih i kvalitativnih karaktera.
Za morfometrijske karaktere izračunati su osnovni parametri
deskriptivne statistike, a za kvalitativne karaktere obrađene
su tri kvalitativne karakteristike sa tri stanja na četiri tjelesna
regiona obične krastave žabe odvojeno po polovima. Što se
tiče morfometrijskih karaktera utvrđena je statistički značajna
razlika između polova.

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INTRODUCTION
Common Toad has a large distribution and popultes mainly the entire palearctic
area. It populates almost the entire Europe, with the exception of far north, Ireland,
Corsika, Sardinia, Balear's Islands, Malta, Crete, as well as some smaller
islands (B o r k i n and V e i t h , 1997). It also populates the northwestern Africa
(P a s t e u r and B o n s , 1959). Although common at lower altitudes, it may also be
found also on altitudes exceedeing 2500 m and on Iberian Peninsula (A n g e l , 1946;
B o r k i n and V e i t h , 1997). In Montenegro it is mainly widely distributed. Owing to
wide distribution, climatic conditions in various parts of areal of distribution are very
different. Thus, in northern part of the areal the winters are long, cold and humid, so
that the period favorable for growth is rather short (J o h a n n e s s e n , 1970). On
higher altitudes the conditions are even more extreme. On the other hand, southern
populations of this species are exposed to much more favorable conditions of outer
environment; therefore the period favorable for growth is much longer.
Species Bufo bufo is a polytypic one. From the scope of this species a taxon
from the Far East has been separated on the level of species Bufo gargarizans
(A n a n j e v a et al. 1998, K u z m i n 1999a, 1999b), and the character of polytype is
determined to it in addition to nominotype subspecies three other ones B. b.
grediscola, B. b. verrucosissimus, B. b. spinosus. If we recognize the fact that
Caucasus Toad (Bufo verrucosissimus) is a separate species (e.g. O r l o v a &
T u n i y e v 1989, A n a n j e v a et al. 1998), than the taxonomic differentiation in scope
of Common Toad is even more limited. Nominotype subspecies is the most widely
distributed (Northern and Southern Europe). The two first subspecies have a limited
geographical area (mountains Gredos and Caucasus), nominotype subspecies is the
most widely distributed (Northern and Central Europe), whereas the areal of
subspecies B. b. spinosus is limited to the region of Mediterranean (northwestern
parts of Africa, southeast Europe, southern Switzerland, Italy as well as the southern
parts of France and Spain).
MATERIAL AND METHODS
A total of 41 specimens has been analyzed, 26 males and 15 females. The
largest part of the material has been collected in mating period. The material has
mainly been manually collected and meredov (a net with a handle) has also been
used.
The samples belong to herpetological collection of the Natural History Museum
of Montenegro; they are kept in 70 % alcohole.
Morphometric analysis has been done on 21 traits which determine size and
form of body and head of tailless amphibians. Measured traits are: L – longthe of body

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from the top of head to the opening of the cloaca; Lpa – length of front exstremity; F –
length of femur measured fromxthe opening of cloaca to knee joint; T – lengthj of
tibiofibula from knee joint to tibiotarsal joint; P – distance from tibiotarsal joint to the
tip of the longest finger (IV); n – length of metatarsus from the internal metatarsal
ridgelet to the tip of the longest finger (IV); DpPa – length of the first finger off front
exstremity; DpPp – length of the first finger of back extremity; Cint – the biggest
length of the internal metatarsal ridgelet; Lc – length of head from the top of head to
jaw joint; Ltc – width of head measured between the jaw joints; Spp – betweeneyes
space between the internal edges of eye lids; Lc – lengh of head from the top of head
to jaw joint; Ltc – width of head measured between jaw joints; Spp – betweeneyes
space between the internal edges of eye lids; Spi – distance betwnn the outer nasal
openings; Spcr – distance between front angles of eye openings; Lo – the largest
length of eyeball; Ltp – the largest width of upper eye lid; Dro – distance from the top
of head to the eye edge; Dno- distance of nasal opening from eye; Lh - length of
cutaneous folds on heels; Lg - length of partoid salivary glands; Wg - width of
salivary glands and weight.
Three qualitative traits (Table 1) with three conditions on four body regions of
toad: head part - dorsal side, dorsal part-dorsal side, head part -ventral side,
abdominal part-ventral side.
The conditions of qualitative traits have been coded in the following manner:
Dorsal side – head part:
1a - round warts, 1b - oval warts, 1c – kidneylike warts; 2a – very protuberant
warts, 2b – protuberant warts, 2c – drawn in warts; 3a – very marked thornlike ends of
warts; 3b – medium marked thornlike ends of warts; 3c – weakly marked thornlike
ends of warts;
Dorsal side - dorsal part:
4a - round warts, 4b - oval warts, 4c - kidneylike warts; 5a – very protuberant
warts, 5b – protuberant warts, 5c – drawn in warts; 6a – very marked thornlike ends of
warts; 6b – medium marked thornlike ends of warts; 6c – weakly marked thornlike
ends of warts;
Ventral side – head part:
7a - round warts, 7b - oval warts, 7c - kidneylike warts; 8a – very protuberant
warts, 8b – protuberant warts, 8c – drawn in warts; 9a – very marked thornlike ends of
warts; 9b – medium marked thornlike ends of warts; 9c – weakly marked thornlike
ends of warts;

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Ventral side – abdominal part:
10a - round warts, 10b - oval warts, 10c - kidneylike warts; 11a – very
protuberant warts, 11b – protuberant warts, 11c – drawn in warts; 12a – very marked
thornlike ends of warts; 12b – medium marked thornlike ends of warts; 12c – weakly
marked thornlike ends of warts;
Trait
Warts shape
Condition
a) round
b) oval
c) reniform
a)very convex
Warts convexity
b) convex
c) inverted
Prominence of thornlike
warts endings
a)very prominent
b)averagely prominent
c)weakly prominent
Table 1. Analysed qualitatie traits in Bufo bufo
Statistical Analysis
Programme package STATISTICA (version 5.0) has been used for statistical
analysis of data. For morphometric characters basic parameters of descriptive
statistics have been separately calculated by genders: medium value ( x ), error of
medium value (SE), standard deviation (SD), minimal (min) and maximal (max) values
traits as well as coeficient of variation (CV). Analysis of sexual dimorphism has been
performed on basic data (untransformed measures for every property), as well as on
standardized residuals on eight traits (L, Lpa, F, T, P, n, Lc, Ltc). Regression of every
property on body length (L) and use of standardized residuals from such a regression
provides for the elimination of the impact of body size. Comparison of differences
between the genders on basic data and on standardised residuals has been performed
by the use of Tukey Test for the samples of uneven size.
For the establishment of the significance of differences in respect of
morphometric characters between the genders analysis of variance (ANOVA) has
been used.
Absolute and relative frequences (%) of the conditions of qualitative traits have
been established. Qualitative traits have been analysed also through the
corresponding analyses.

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RESULTS AND DISCUSSION
Morphometric Characters
Former data on values of morphometric characters of the species Bufo bufo are
rather insufficient, or, some of them have been given only descriptively. That is why
we have presented here the average values for a large number of characters that
have not been previously analyzed and data about that do not exist in the literature.
Basic parameters of morphometric characters descriptive statistics have been
presented separately by sexes in the table 2. The smallest male of the sample of the
population from Biogradsko Lake is 64.28, and the largest one 82.54 mm. The
smallest female is 90.94 mm, and the largest 109.94 mm. Obtained values of body
size of common toad from Biogradsko Lake are within the limits of the so far recorded
values from other parts of areal of the species. (R a d o v a n o v i ć , 1951; A r n o l d and
B u r t o n , 1978; Đ urović et al, 1979 etc).
Sexual dimorphism has been analyzed in scope of population (localities) by
application of Tukey test for samples of unequal size (“Unequal N HSD Tukey” test).
This test has shown an expressed sexual dimorphism, where the females have higher
average values of analyzed traits (Table 2). On basis of calculated parameters of
descriptive statistics, separately by sexes and on basis of compared differences
between the sexes, it has been established that the females have statistically higher
values of all the characters, especially when the word is about L – body length, Lpa –
length of front extremity, Lc – head length, Ltc – head width, Lg – length of salivary
glands, weigth.
With the population of Biogradsko Lake a great number of traits that have been
demonstrating sexual dimorphism by the analysis of basic data where the size has
been included, indicate the absence of sexual dimorphism for the largest number of
characters when body size is excluded. The charactereistics which demonstrate the
presence of sexual dimorphism also after the eliminating body size are T- length of
tibiofibula and F – length of femur.
Females are bigger than males in a large number of amphibian species
(S h i n e , 1979; M i a u d et al., 1999; K h o n s u e et al.., 2001a, 2002b; M o n n e t and
C h e r r y , 2002). That has been especially expressed with tailless amphibians in
which females are bigger than males with 90% of species (S h i n e , 1979). This has
also been established in this paper for studied population from Biogradsko Lake, as
well as for the populations of the remaining part of the areal of distribution of this
species (G i t t i n s et al., 1980; H e m e l a a r , 1988). The most common explanation of
sexual dimorphism in body size is the advantge the females have in respect of eggs
production (H a l l i d a y and V e r r e l l , 1986; C v e t k o v i ć et al., 2003). Namely,
there is a positive correlation in many groups between body length and fecundity
(C u m m i n s , 1986; B e r v e n , 1988; S i n s c h , 1998; G i b b o n s and M c C a r t h y ,
1986). Assumption is that the selection, owing to a pointed correlation of body length

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Males Females sexual dimorphism
Unequal N HSD (Tukey)
Trait N Means SD SE Min Max N Means SD SE Min Max basic data/standard results
L 26 73.71 4.1447 0.8128 64.28 82.54 15 100.64 5.0865 1.3133 90.94 109.94 ***
Lpa 26 54.62 3.6473 0.7153 46.68 63.17 15 71.64 3.7562 0.9699 62.23 77.60 ***/ns
F 26 32.53 3.1809 0.6238 25.32 38.86 15 40.67 4.9746 1.2844 31.98 46.95 ***/***
T 26 24.10 2.0556 0.4031 20.52 27.25 15 28.82 2.4023 0.6203 25.55 34.46 ***/**
P 26 36.65 4.2990 0.8431 27.03 42.91 15 42.98 2.8349 0.7320 37.06 47.03 **/ns
n 26 51.90 4.6742 0.9167 43.30 60.54 15 62.52 4.8611 1.2551 56.26 72.83 ***/ns
n-P 26 15.25 4.0443 0.7931 7.26 22.45 15 19.54 4.4970 1.1611 12.24 27.70 **
DpPa 26 6.58 0.7584 0.1487 5.10 7.99 15 10.44 1.5234 0.3933 7.48 13.45 ***
DpPp 26 6.74 0.8867 0.1739 5.29 8.63 15 8.46 1.2908 0.3333 5.85 10.79 ***
Cint 26 4.53 0.5892 0.1155 3.37 5.56 15 6.34 0.9030 0.2331 4.51 7.74 ***
Lc 26 17.50 1.1857 0.2325 14.28 19.46 15 24.69 1.6894 0.4362 22.04 27.83 ***/ns
Ltc 26 22.41 1.5435 0.3027 19.67 24.73 15 31.19 2.0888 0.5393 28.09 36.37 ***/ns
Spp 26 8.75 0.9524 0.1868 6.72 10.92 15 12.55 1.6316 0.4213 9.75 15.07 ***
Spi 26 4.03 0.5097 0.1000 2.85 4.92 15 5.32 0.6099 0.1575 4.39 6.47 ***
Spcr 26 7.49 0.5751 0.1128 6.28 8.62 15 11.82 0.9789 0.2528 10.28 14.21 ***
Lo 26 6.25 0.6112 0.1199 4.95 7.43 15 9.28 0.7010 0.1810 7.61 10.27 ***
Ltp 26 5.88 0.6321 0.1240 4.32 6.71 15 7.80 0.8845 0.2284 5.72 9.61 ***
Dro 26 7.54 0.5957 0.1168 6.27 8.75 15 10.72 0.8648 0.2233 9.42 12.33 ***
Dno 26 3.22 0.3864 0.0758 2.59 4.08 15 4.49 0.5739 0.1482 3.54 5.41 ***
Lh 26 3.56 0.5723 0.1122 2.65 4.77 15 5.09 0.3795 0.0980 4.49 5.81 ***
Lg 26 14.86 1.7528 0.3438 11.78 18.10 15 20.77 2.2236 0.5741 17.04 24.34 ***
Wg 26 5.80 0.7387 0.1449 4.53 7.50 15 8.20 1.0614 0.2741 6.48 10.06 ***
Weight 26 44.50 6.4576 1.2664 33.00 56.00 15 141.07 31.1367 8.0395 97.00 230.00 ***
Table 2. Basic parameters of descriptive statistics of males and females of Biogradsko Lake and Tukey (HSD) test with gender factor

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and fecundiy, favorises several values for body length of females. Greater eggs
production on the other hand is explained by larger internal space for their storage,
which larger females have (A n d e r s o n , 1994).
The direction and magnitude of dimorphism in body length depend of various
selective pressures the specimens of male and female sex are exposed to. D a r w i n
(1871) assumed that sexual selection (though the competition among the specimens
of the same sex or through an active selection of partner), may lead to sexual
dimorphism. For instance, in species with pointed struggles among the males, males
are frequently bigger than females.
However, it is important to underline that common toad is one of rare secies in
which males are a smaller sex, although there are struggles for females among them
(H a l l i d a y and V e r r e l l , 1986; A r a k , 1988).
Qualitative Analysis
By a comparison of rerlative frequency of condition of monitored qualitative traits
it has been noted that the same conditions, as a rule, have the greatest frequency
both in the sample of males and in the sample of females (Tabele 3). The exception is
the convexity of of warts in head region (in males the largest relative frequency have
the warts which are indented, and with females warts are very protuberant) and the
appearance of thornlike endings of ventral side of head region (most frequently weakly
expressed in males and averagely expressed in females). The table of relative
frequency of the conditions indicates that with females the variability of condition is
higher than with males.
By a correspondant analysis we have monitored the impact of qualitative traits
on ordination of specimens of both sexes. The first corresponding axis has separated
24.69% of variability, and the other one 17.03%. There is no clear sex separation
(Figure 1). The sample of males indicates an uniformity in respect of monitored traits.
Only one male has been separated during the second coresponding axis from the
„main cloud” of male specimens on basis of two traits (11b and 12b) (Figure 2). One
may observe a higher variability in scope of the sample of females. Traits 1c, 4b and
5a separate two females along the first correspoding axis from other females, where it
should be mentioned that these two traits as well as the traits 2a, 3b and 6b influence
separating of females from males (Figures 1 and 2).
The significance of this paper is in presenting for the first time the analysis of a
larger number of morphometric and qualitative characters of population of the species
Bufo bufo from Biogradsko Lake. These data make the grounds for further
investigations of the populations of the species Bufo bufo both from Biogradsko Lake
and the populations of this species from the territory of entire ontenegro.

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Received: 20.10.2007.

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