A case of melanism in a population of the insular lizard Podarcis hispanica atrata

5 Pages·1994·0.57 MB·

by  Castilla, A M

A case of melanism in a population
of the insular lizard
Podareis hispaniea atrata
Aurora M. CASTI LLA
Castilla, A.M, 1994. A case of melanism in a population of the insular lizard
Podareis hispanica atrata. BoII. Soco Hist. Nat. Balears, 37: 175-180 ISSN, 0212-
SHNB
260-X. Palma de Mallorca.
@ In the essay the finding and some morphological characteristics of a melanic
example of Podarcis hispanica atrata found on the Columbretes archipelago
(Castellón, Spain) is described.
Key words: Mediterranean islands, lizard, melanism, endangered, endemism, age.
UN CASO DE MELANISMO EN UNA POBLACiÓN INSULAR DE LA LAGARTIJA.
En este estudio se describe el hallazgo y algunas características morfológicas de
un ejemplar melánico de Podareis hispanica atrata encontrado en el arhipiélago
SOCIETAT D'HISTORIA de las islas Columbretes (Castellón, España).
NATURAL DE LES BALEARS Palabras clave: Islas mediterráneas, lagartija, melanismo, en peligro, endemismo,
edad.
Aurora M. CASTILLA. Instituto de Estudios Avanzados de las Islas Baleares
(CSIC), Ctra. Valldemossa, Km. 7,500, E-07071 Palma de Mallorca, Spain, and
Department of Biology, University of Antwerp (UIA) , B-2610 Wilrijk, Belgium.
Recepeió del manuscrit, 30-juny-94. Revisió acceptada, 11-oct-94
In this paper I describe the' finding nean ca. 57 km off the coast of Cas
and some morphological and behaviou tellón (province of Castellón, Spain).
ral characteristics of a melanistic indivi Both males and females show a great
dual of the lizard Podareis hispaniea individual variability in the ventral colour
atrata. This is an endangered lizard and dorsal colour pattern. The latter
whose world range is restricted to the ranges from pale uniform green to
Columbretes islands (39° 54' N, 0° 41' brownish-green with black reticulate
E) (see detailsin Castilla & Bauwens, spots(Castilla, L. Bauwens, ,in press).
1991 b). These constitute an archipela This subspecies' of lizard was
go of small uninhabited islets of vol described by Boscá (1916) on the base
canic origin situated in the Mediterra- of a single individual that was brought
176 BoII. Soco Hist. Nat. Balears, 37 (1994)
to him by a fisherman as a curiosity. The body size (snout-vent length =
The subspecific name alrala (Latin = 68.9 mm) and weight (8.86 g) of the
dressed in black) refers to the black melanistic individual was aboye the
colour of that individual (Boscá, 1916). average recorded for adult male lizards
Since that date, however, no other in that population and year (Castilla L
melanistic individual has been seen or Bauwens, in press). In other species of
collected on the archipelago by reptiles, melanistic males attain a larger
herpetologists who made short-term body size than normally coloured
visits to the islands in different periods individuals (Lovich et al., 1990). Upon
(Eisentraut, 1930; Klem mer, 1961). its first capture, I estimated that the
During the years 1984-1994 I have melanistic individual was at least two
performed detailed studies of the lizards years old. The lizard was maintained
on Columbretes (see Castilla et al, temporarily in captivity during 1991.
1987; Castilla & Bauwens, 1991 a, Afterwards, it was obseNed in the study
1991 b; Castilla & Swallow, in press), area until October 1994, thus attaining
during which I handled several hundreds an age of at least five years. No pre
of individuals, and closely observed cise information is available on the age
many others. Despite my intensive of other individuals from Columbretes.
sampling efforts, only a single melanistic Nevertheless, data from a Portuguese
individual was caught in May 1991 on population of P. h. hispanica indicate
the northern and highest (ca. 70 m) that the maximal age did not exceed
part of the island Columbrete Grande three years (Caetano et al., 1986). I
(Figure 1). Thus, the occurence of suggest that the large body size of the
melanism seems to be an extremely melanistic lizard, and the reduced
rare event in P. hispanica alrala. predation pressure on Columbretes (see
The melanistic individual was an in Castilla and Bauwens, 1991 a,b) may
adult male that had a coal bright have contributed to the advanced age
uniform black cOlour, only the belly (at least 5 years) attained by this indi
presented a black reddish coloration. vidual.
This black coloration was darker than The rare occurence of melanistic
the black-greyish colour described for a individuals has been observed in conti
melanistic individual of Podarcis h. his nental populations of other lacertid
panicá found in the Iberian Peninsula lizards. Some examples are P. hispani
(Pérez-Mellado, 1984). The single me ca (Pérez-Mellado, 1984) and P. muralis
lanistic individual was observed throu (Zuffi, 1986; Barbadillo and Sánchez
ghout 1991-1994 and did not change Herráinz, 1992). It has been suggested
his uniform bright black coloration. that melanism is relatively common at
Hence, this must not be considered as northern latitudes (Kuranova, 1989), as
a case of temporary melanism as for example in the lacertids P. muralis
described for turtles (Lovich et al., (Bruno and Maugeri, 1971), Lacerta
1990) and other vertebrates (see refs. vivipara (Malkmus, 1976), and L. agilis.
in Sage, 1962), but instead, as a type On the other hand, some insular
of permanent melanism as defined in populations of mediterranean lizards
Lovich et al. (1990). (e.g. P. dugesii, P. li/fordi, P. pityusen-
Fig. 1. Melanistie male 01 Podareis hispaniea atrata in the Mediterranean island Columbrete
Grande (a) (A M. Castilla) and detail 01 the head (b) (L.J. Barbadillo)
Fig. 1. Macho mel¿mico de Podareis hispaniea atrata en la isla Mediterránea de Columbre te
Grande (a) (A M. Castilla) y detalle de la cabeza (b) (L. J Barbadillo).
178 Bo/l. Soe. Hist. Nat. Balears, 37 (1994)
sis) consist entirely of melanistic Bruno, S. & Maugeri, S. 1977. Rettili
individuals (Bischoff et al., 1989; Pérez d'ltalia. Tartarughe- Sauri-Serpenti.
Mellado, 1989; Cirer and Martínez Rica, Giunti Martello, Firenze.
1990). In general, it has been sugges Caetano, M. H.,Castanet, J. & Crespo,
ted that conditions associated with insu E. G. 1986. Estimation a I'aide de
larity, either on oceanic islands or on la squelettochronologie de I'age de
restricted alpine habitats, could favour Podareis hispaniea (Steindachner,
the apparition of melanistic forms. 1870), Sauria, Lacertidae, provenant
d'une population portugaise. Revue
suisse Zool .. 93:117-127.
Acknowledgements
Castilla, A. M. & Bauwens, D. 1991a.
Thermal biology, microhabitat selec
Permission to work in the island tion, and conservation of the insular
and transport to it was made possible
lizard Podareis hispaniea a trata.
by the Conselleria D'Medi Ambient
Oeeologia. 85: 366-374.
(Generalitat Valenciana), the Dirección
Castilla, A. M. & Bauwens, D. 1991 b.
General de Puertos of Castellón, and
Observations on the natural history,
the Jefatura Provincial de Aduanas of
present status, and conservation of
Castellón. Valentín Tena, Javier Martí
the insular lizard Podareis hispaniea
nez, Antonio Sanchez and Santiago
atrata on the Columbretes archipe
Sales provided help during observations.
lago, Spain. Biologia, Conservación
My studies on Columbretes were funded
de la lagartija Podareis hispaniea
by a grant of the Spanish M.E.C., the
atrata en las islas Columbreles. Ed.
Project DGICYT (PB91-0055), and the
Generalitat Valenciana Consellería
Exmo. Ayuntamiento de Castellón.
de Medio Ambiente, Valencia 58: 69-
84.
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