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Acta Herpetologica 10(2): 135-141, 2015
ISSN 1827-9635 (print) © Firenze University Press
ISSN 1827-9643 (online) www.fupress.com/ah
DOI: 10.13128/Acta_Herpetol-16194
Malformations and body injuries in a hybrid zone of crested newts
(Caudata: Salamandridae: Triturus cristatus superspecies)
Z M1, L J2, A R3, M R1, D J4
1 Department of Ecology and Environmental Sciences, Palacký University in Olomouc, Šlechtitelů 27, 78371, Olomouc, Czech Republic.
Corresponding author. E-mail: zdenek.macat@gmail.com
2 Nature Conservation Agency of the Czech Republic, Kaplanova 1931/1, 14800, Praha 11 - Chodov, Czech Republic
3 South Moravian Museum in Znojmo, Přemyslovců 129/8, 66902, Znojmo, Czech Republic
4 Department of Zoology, Comenius University in Bratislava, Mlynská dolina B-1, 84215, Bratislava, Slovakia
Submitted on 2015, 12th May; revised on 2015, 6th October; accepted on 2015, 9th October
Editor: Sebastiano Salvidio
Abstract. Morphological abnormalities occur frequently in wild amphibian populations. We analysed malformation
and injuries in the hybrid zone of three crested newt species, in the Czech Republic. In total, 274 individuals from 35
localities in South Moravia (Czech Republic) were examined during the period 2010-2014. Malformations were found
in eight newts (2.9%) from seven localities. Injuries were recorded on 59 newts (21.5%). Proportions of tail crest inju-
ries was signicantly higher (P ˂ 0.1) in males than in females and the probability of being injured was signicantly
higher (P ˂ 0.01) for adult individuals. We discuss gene mutation, parasitism and predation as possible explanations
for our observations.
Keywords. Amphibia, Triturus cristatus, morphology, abnormalities, polydactyly, limb damages, contact zone, Czech
Republic
Pre- or post-natal malformations are regularly
reported in dierent amphibian species (Canestrelli et al.,
2006; Piha et al., 2006; Sas and Kovacs, 2006; Machado et
al., 2010; Jarvis, 2011; Henle, et al. 2012; Gatti and San-
nolo, 2014). In general, amphibian abnormalities include
malformation and injuries, and according to Reeves et al.
(2008) and Hassine et al. (2011), the most common mal-
formations in amphibian are: i) eye abnormalities such as
anophtalmia or microphtalmia, ii) skeletal injuries such
as brachydactyly (short digits), ectrodactyly (missing dig-
its) or ectromelia (partial limb formation), iii) skeletal
malformations such as amelia (missing limb), polydactyly
(extra digits), syndactyly (digits fused), brachygnathia
(short jaw), iv) surcial abnormalities such as incom-
plete tail resorption or skin trauma (e.g., scars, edema).
Along with colour abnormalities (e.g., leucism, albinism
or axanthism) these malformations are recorded in the
wild life of amphibians (Jablonski et al., 2014). Malfor-
mations could be a result of genetic mutation caused by
environmental pollutants, parasites, diseases, prenatal
stress, genetic predisposition or UV radiations (Blaustein
and Johnson, 2003).
On the other hand, injuries in wild animals can orig-
inate from diseases, intraspecic aggression, and most of
all by predation (Lima and Dill, 1990). Injuries are usu-
ally studied in animals that have the ability to autotomize
a body part (Cooper et al., 2004; Maginnis, 2006) or to
regenerate a missing part, which is aer this process actu-
ally dierent from the original part (Maginnis, 2006).
Frequency and types of injuries are probably connected
with density and diversity of predators, with geographical
dierences in injury rates among population (Placyk and
Burghardt, 2005) and sexes (sexual dimorphism) in the
breeding season (Kopecký, 2013).
In this article, we present results of our study on
morphological abnormalities found in crested newts from
136 Zdeněk Mačát et alii
their hybrid zones in the Czech Republic. Studied locali-
ties are southern parts of the Czech Republic (Znojmo
region), where the ranges of three crested newt species
meet: Triturus cristatus (Laurenti, 1768), T. dobrogicus
(Kiritzescu, 1903), and T. carnifex (Laurenti, 1768) (Wiel-
stra et al., 2014). eir distribution is parapatric with
mixed contact zone in South Moravia, the only known
among these species in the Czech Republic (Mikulíček
et al., 2012). Despite malformations of amphibians are
relatively well known, the following paper provides a new
point of view on their causes.
During the period 2010-2014 we recorded body
abnormalities and injuries at Triturus cristatus superspe-
cies in Znojmo region (South Moravia, Czech Republic).
During the breeding season, 274 individuals (136 males,
127 females and 11 subadults) in the water phase from 35
localities, were examined. Newts were captured by fun-
nel collapsible nylon baited traps (Bock et al., 2009; Mad-
den and Jehle, 2013), sexed, measured and photographed
from dorsal and lateral side of the body. Each locality
was visited once, in case of sucient number of caught
newts (more than 10 individuals). Otherwise these locali-
ties were repeatedly visited. Individuals from all popula-
tions were recognized by belly pattern from photographs
(according to Hagström, 1973; Jehle et al., 2011). Dier-
ences between males and females and between bigger and
smaller individuals were performed on tail injuries by the
soware STATISTICA 12 (Hill and Lewicki, 2007), using
a nonparametric Mann-Whitney U test.
Malformations were recorded at seven localities
(Table 1, Fig. 1). Each malformation was recorded in
dierent locality, except two cases (locality Podmolí 2).
Articial pond was the most frequent type of habitat
with morphological abnormalities (four cases); two were
situated to the wood ponds and other cases represented
dierent types of ponds. e distance between the two
nearest localities was 0.2 km (Podmolí 1 and Podmolí 2)
separated by road. ere is no evidence about identical
belly pattern between newts in these localities. e long-
est distance between two localities was 18.8 km (Bojanov-
ice and Chvalatice). Eight out of 274 individuals (2.9%)
showed malformations of three dierent types: bidactyly,
polydactyly and syndactyly (Table 1, Fig. 2). Bidactyly
was recorded ve times (1.9% of all individuals) while
polydactyly two times (0.7%) and syndactyly one a time
(0.4%). Overall, three male individuals (average SVL:
71.9 mm) and ve females (86.8 mm) were recorded with
malformations.
Fiy-nine out of 274 newts (21.5%) were injured.
Male individuals were injured in 28 cases (47.5%) and
females in 31 cases (52.5%). Injuries could be divided
into six types. e rst type consisted of damage to the
front limb (including arms and ngers; Fig. 3E, G, H)
and the second type consisted of a damage to the hind
limb (Fig. 3F). Two types of injuries were recorded on
tail: damage (ragged) on the tail crest and missing the tip
of the tail (Fig. 3A-D). ere was some interesting dif-
ferences between males and females: while males were
injured on the crest of tail, females were injured on the
tip of the tail. e last two injuries types were recorded
on the body (trunk) and the head. e most common
injury was damage to the tail (32 cases, 71.2%, Fig. 4).
e second most recorded was damage to the limb (15
cases, 25.4%). Furthermore, two atypical injuries were
found: one female had fresh scars on the trunk and tail
(Fig. 3I) and another female had a hole in the throat (Fig.
3J). e proportion of tail crest injuries was signicant-
ly higher for males (14 cases) compared to females (P <
0.1). e probability of injuries was signicantly higher
for bigger newts (average 76.9 mm) compared to smaller
ones (average 72.1 mm; P < 0.01).
We observed three types of malformation in the T.
cristatus superspecies (bidactyly, polydactyly and syn-
dactyly). Several cases of morphological malformation
among the genus Triturus are known from available lit-
erature: bidactyly in three individuals of T. cristatus from
the United Kingdom (Jarvis, 2011), polydactyly in two T.
carnifex from Italy (Gatti and Sannolo, 2014), polyme-
Table 1. Malformation recorded in Triturus cristatus superspecies during the study (SVL - snout-to-vent length; TL - tail length).
Figure Sex SVL TL Malformation Locality GPS Altitude Pond type Date
1A F 78.4 52.9 bidactyly Čížov 48.88N, 15.88E 400 m articial 28 April 2010
1B F 89.9 69.8 polydactyly Onšov 48.90N, 15.84E 460 m natural forest 22 April 2011
1C F 94 80.9 bidactyly Podmolí 2 48.84N, 15.93E 406 m articial 25 May 2011
1D M 75.4 56.1 bidactyly Podmolí 2 48.84N, 15.93E 406 m articial 25 May 2011
1E F 90 60.8 bidactyly Podmolí 1 48.84N, 15.93E 412 m sh pond 27 April 2012
1F F 82 54 bidactyly Lukov 48.86N, 15.89E 444 m forest wetland 29 April 2013
1G M 66.4 51.6 polydactyly Bojanovice 48.94N, 16.00E 350 m articial 10 May 2013
1H M 73.9 52.8 syndactyly Chvalatice 48.93N, 15.74E 446 m articial 2 April 2014
137
Malformations in Triturus cristatus
ly in T. marmoratus (Recuero-Gil and Campos Asenjo,
2002) and malformation of digits between hybrids of T.
cristatus and T. marmoratus in western France (Arntzen
and Wallis, 1991). Malformation rates in amphibians
do not exceed 5% in healthy populations (Blaustein and
Johnson, 2003). In comparison with other authors study-
ing crested newts (Jarvis, 2011; Gatti and Sannolo, 2014;
Mester et al., 2015), the malformation rate found in this
study is relatively high. On the other hand, malformation
rate shows much higher uctuations among other species
of Caudata: e.g., about 3.9% at Calotriton arnoldi (Mar-
tínez-Silvestre et al., 2014) or about 40-90% at Crypto-
branchus alleganiensis (Hiler et al., 2005).
Amphibians seem particularly prone to malforma-
tion (e.g., polydactyly). e extreme sensibility to envi-
ronmental changes and habitat loss are well known in
amphibians, including crested newts (Beebee and Grif-
ths, 2005). However, we have no data to suppose that
pollution (some localities are situated into national park,
where we can assume low levels of pollution) caused
observed abnormalities. Five main factors could possibly
cause malformations: i) hyper-regeneration aer preda-
tor attempts or accidents (Eaton et al., 2004; Ballengée
and Sessions, 2009), ii) exposition to high UV-B radiation
(Blaustein et al., 1997; Pahkala et al., 2003), iii) chemi-
cal pollution from industry and agriculture (Kiesecker,
2002; Piha et al., 2006), iv) degradation of the environ-
ment (Houlahan et al., 2000) and v) parasite infection
(e.g., Ribeiroia trematodes; Kiesecker, 2002; Johnson and
Chase, 2004). In addition, body malformations could also
be caused by hybridization. Dierent crested newt spe-
cies cross in narrow hybrid zones (Arntzen et al., 2014).
Arntzen and Wallis (1991) discussed the relatively high
proportion of malformation within Triturus hybrid zone
caused by collapsed genetic homeostasis. A much lower
proportion of malformation is reported away from crest-
Fig. 1. Distribution map of Triturus cristatus superspecies (T. cristatus - pink, T. carnifex - purple, T. dobrogicus - orange; e colours in the
overlap indicate putative contact or hybrid zones; sensu Wielstra et al., 2014) in study area and locations of localities with records of malfor-
mations (1 - Chvalatice, 2 - Onšov, 3 - Lukov, 4 - Čížov, 5 - Podmolí 2, 6 - Podmolí 1, 7 - Bojanovice; see Table 1.).
138 Zdeněk Mačát et alii
ed newt hybrid zones (Jarvis, 2011; Gatti and Sannolo,
2014, Mester et al., 2015). erefore, hybridization could
be the likely explanation for our results.
Crested newts are active swimmers, therefore, the
injuries of tail or limbs could negatively aect their t-
ness. Under natural conditions, injured individuals are
easily liable to become a prey for predators (Kopecký,
2013). e relatively high percentage of injured individu-
als in our study (compare with Székely and Nemes, 2003;
Kopecký, 2013) could be probably caused by predators,
such as water birds, small mammals or invertebrates (e.g.,
dragonfly nymph, Bowerman et al., 2010). Moreover,
some injuries could emerge from stocking sh for sh-
ing, such as Carassius gibelio (Bloch, 1782), Pseudorasb-
ora parva (Temminck and Schlegel, 1846) and Ameiurus
nebulosus (Lesueur, 1819) (Lusk et al., 2010).
Taking into account the syntopic occurrence of the
three crested newt species, competition within species is
also possible. Considerable sexual dimorphism during
breeding phase is well known, in which males are more
brightly coloured than females (e.g., Griths, 1996; Jeh-
le et al., 2011). Moreover, males are territorial and ghts
between them are known (Griths, 1996). us, we can
expect that males are probably more frequently injured
than females (cf. Kopecký, 2013). Our results concern-
ing tail injuries partly support this hypothesis. As a sim-
ple explanation, we consider male tails to be more visu-
ally attractive for predators and they have dierent shape
Fig. 2. Malformation recorded during the study of crested newt (for
details see Table 1).
Fig. 3. Examples of injuries recorded during the study of crested
newts (A-D tail damage, E-H missing toes or limb, I-J scars and tis-
sues damage).
139
Malformations in Triturus cristatus
and dimension than female tails. Kopecký (2013) did not
nd any intersexual dierence, although injuries at tail
tip were more frequent (but not signicantly) in females.
Kopecký (2013) offers an explanation for mechanical
damage to tail during underground movement in narrow
spaces at terrestrial phase/hibernation. It is undisputed,
that all types of injuries (loss of limbs, ngers or tail) can
signicantly impair walking, running, swimming, gliding,
diving and could be a risk for disease infection (Cooper
et al., 2004; Maginnis, 2006; Marvin, 2010). Our results
suggest that larger (and presumably older) individuals are
injured more oen probably because body size at crested
newts increases signicantly with age (Rehák, 1983; Hal-
liday and Verrell, 1988). Moreover, older animals will
also accumulate injuries on their body. Nevertheless,
these accumulations do not need to be necessarily lethal
for amphibians as was found by Mott and Steen (2013)
who reported the association between body size and non-
lethal injuries in amphibians.
ACKNOWLEDGEMENTS
We are very grateful to Ben Wielstra (Sheeld) and
two anonymous reviewers for their valuable comments,
which improved previous versions of the manuscript.
Also, we would like to thank Adam Bednařík (Olomouc)
for technical support and people, which were helpful dur-
ing the eld survey: Lenka Reiterová (Čížov), Miroslav
Maštera (Kostelní Myslová), Václav Křivan (Štěměchy)
and Podyjí National Park Administration for providing
important facilities. Field study was supported by IGA
PřF UPOL: No. IGA_PrF_2015_008, Norway Grants: No.
76213/ENV/10, 5458/610/10 and Monitoring program of
Nature Conservation Agency of the Czech Republic: No.
PPKB 10/09/11. All handling of animals was carried out
under permits number 32118/ENV/11-1156/620/11-PP18
and 27586/ENV/14-1544/630/14.
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