Herpetological Conservation and Biology 16(2):386–393. Submitted: 17 January 2021; Accepted: 16 July 2021; Published: 31 August 2021. CANNIBALISM IN THE SPANISH ALGYROIDES (ALGYROIDES HIDALGOI, LACERTIDAE): ECO-EVOLUTIONARY IMPLICATIONS? 1 JOSÉ LUIS RUBIO AND ALEJANDRO ALONSO-ALUMBREROS Departamento de Ecología, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain, and Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, C. Darwin 2, E-28049, Madrid, Spain 1Corresponding author, e-mail: [email protected] Abstract.—Cannibalism is a widespread behavior, although relatively less reported in reptiles than other taxa. Many studies indicate its importance in population regulation and life history of the species concerned, while others regard it as an opportunistic behavior. We present the first report of cannibalism in the Spanish Algyroides (Algyroides hidalgoi), a small and stenotopic lacertid lizard that occupies rocky shaded and humid localities in a reduced distribution area in the southeastern mountains of the Iberian Peninsula. Within an ongoing study of the species trophic ecology, we found tail-scales of this lizard within a fecal pellet. By studying the morphology and microornamentation of the scales, we identified the victim as an adult conspecific, and we discuss the implications of the event within the framework of the particularities of the species. While cannibalism by lizards has been associated mainly with high lizard population densities and unproductive and predator-scarce environments (mainly islands), the Spanish Algyroides shows nearly the opposite characteristics. The scales found represent a very small proportion of the studied ingested prey. Cannibalism seems not to have important demographic implications in this species. The case adds to other cannibalism reports that do not find adaptive value of this behavior in lizards, and contributes to the discussion found in the literature (opportunism vs adaptation) stressing the need of further research. Key Words.—conspecific predation; feeding behavior; lacertids; lizards; scale microornamentation; Spanish Algyroides Resumen.—El canibalismo es un comportamiento muy extendido, aunque relativamente menos descrito en los reptiles que en otros grupos zoológicos. Muchos trabajos señalan su importancia en la regulación de poblaciones y la estrategia vital de las especies implicadas, mientras que otros lo consideran un comportamiento oportunista. Presentamos el primer caso de canibalismo en la Lagartija de Valverde, Algyroides hidalgoi, un lacértido muy pequeño y estenotópico que ocupa localidades umbrías y húmedas en un área de distribución muy reducida en las sierras surorientales de la Península Ibérica. Durante un estudio en curso sobre la ecología trófica de la especie, encontramos escamas caudales de esta lagartija en uno de los excrementos. El estudio de la morfología y la microornamentación de las escamas, nos permitió identificar la víctima como un conspecífico adulto. Discutimos las implicaciones del evento en el contexto de las particularidades de la especie. Mientras que el canibalismo en los lagartos y lagartijas se ha asociado principalmente a densidades de población altas y medios poco productivos y con escasa presión de depredación (principalmente en islas), la Lagartija de Valverde parece mostrar características prácticamente opuestas. Las escamas encontradas representan una proporción muy baja en nuestra muestra de presas consumidas. El canibalismo no parece tener gran importancia en la demografía de esta especie. El caso se suma a otros registros de canibalismo que no encuentran valor adaptativo en este comportamiento en lagartos y lagartijas, y contribuye a la discusión existente en la literatura (oportunismo vs adaptación), enfatizando la necesidad de futuras investigaciones. Palabras Clave.—comportamiento de alimentación; lacértidos; Lagartija de Valverde; lagartos y lagartijas; microornamentación de escamas; predación intraespecífica. INTRODUCTION both vertebrates and invertebrates (Fox 1975; Polis 1981; Polis and Myers 1985; Pfenning 1997) and has Cannibalism is widespread in many zoological received relatively less attention in an eco-evolutionary groups (Fox 1975; Polis 1981; Pfenning 1997), and context (but see for instance Ohlberger et al. 2020 it has been the subject of many field and laboratory and references therein). Many studies on reptilian studies. In reptiles, cannibalism has been reported in cannibalism consider this behavior (as in other animals) many species, albeit with relatively lower frequency and highly significant for the population dynamics and life intensity, particularly in lizards, than in other groups, history of the species concerned (e.g., Cushing 1992; Copyright © 2021. José Luis Rubio 386 All Rights Reserved. Herpetological Conservation and Biology Dong and Polis 1992; Mateo and Pleguezuelos 2015; et al. 1974; Sánchez-Videgaín and Rubio 1996). The Dias et al. 2016; Ohlberger et al. 2020). In this sense, objective of this study was to confidently identify lizard cannibalism is considered to have high adaptive value, scales within a scat and to estimate its size/age class by even in cases with low intra-population cannibalism studying the morphology and microonamentation of the frequency (e.g., Fox 1975; Polis 1981; Cushing 1991). scales. We also discuss this case within the Opportunism Some studies emphasize the implications of cannibalism versus Eco-evolutionary Framework considering the in the energy budget at individual and population level particularities of our predator. (Rootes and Chabreck 1993). Lacertilian cannibalism has been mainly associated with situations of food MATERIALS AND METHODS shortage (Carretero et al. 2010; Cooper et al. 2015; Torres et al. 2019; but see Fox 1975), and frequently studied on Caudal scales of the Spanish lacertid lizards are easily islands with low predator pressure and high population distinguished morphologically from the rest of the body densities of lizards (e.g., Castilla and Van Damme 1996; scales because they are typically elongated, more or less Carretero et al. 2010; Cooper et al. 2015). Other authors keeled, superimposed, and pointed backwards (Salvador have simply seen opportunism in this behavior, related 2014). This was true of the scales we found in a scat and to the generalist trophic-strategy widely attributed to of those of the sympatric lacertid lizards sharing the area most species of lizards, and considering the low relative with A. hidalgoi. We positively determined our sample frequency of cannibalistic events found in lizards (e.g., as lacertid lizard caudal scales. Regarding the other Polis and Myers 1985; Amat et al. 2008; Carretero et candidate species, the gekkonid T. mauritanica can be al. 2010; Sales et al. 2011; Van Kleeck et al. 2018). eliminated as a possible victim due to its large wide, Interspecific lizard saurophagy is also common (Alemán granular, caudal scales, which differ greatly from our and Sunyer 2014; Van Kleeck et al. 2018; Andriopoulos focal scales. The scales of the lacertid Psammodromus and Pafilis 2019; Christopoulos et al. 2020), as well as algirus are also quite different, being wide, strongly keratophagy, the consumption of reptilian shed skin keeled and pointed (Fig. 1). This left three remaining (Groves and Groves 1972; Mitchell et al. 2006; Vacheva candidates. Timon lepidus is a large lizard (SVL: adults 2018). < 260 mm, hatchlings = 40 mm; Arnold and Ovenden Here we report the first evidence of cannibalism in the 2002; Mateo 2017), but we included it in the study Spanish Algyroides (Algyroides hidalgoi; Lacertidae). because it was possible that a piece of tail (perhaps from This lizard was formerly Algyroides marchi (see a juvenile) had been eaten. Podarcis virescens is a more Sánchez-Vialas et al. 2019 for a taxonomical review). In comparable lizard in size and general morphology to A. the course of an ongoing study of the trophic ecology of hidalgoi. A. hidalgoi, we found within a fecal pellet from an adult For an interspecific comparison of the scale male with a snout-vent length (SVL) of 43.8 mm two morphology, we considered the shape, symmetry, width contiguous partial whorls of scales of the tail of a lizard (W, at the scale transversal midline) and length (L, from (sum of 19 scales; Fig. 1). The Spanish Algyroides is tip to the proximal scale base visible under the previous one of the smallest lacertid lizards (SVL < 50 mm), scale) of a scale, and we estimated the scales surface and it inhabits a small geographic distribution (Rubio (L × W in mm2) and elongation (L/W). For each lizard 1997, 2002) occupying an area less than 5,000 km2 in species (three specimens per species), we sampled one the southeastern mountains of the Iberian Peninsula scale, dorsal and ventral, from every 10 caudal-scale (Prebetic ranges, sensu Sánchez 1982). The species is a whorls, from the tip to the proximal tail (where scales stenotopic lizard, concentrating mostly in limited rocky, morphology change to body-scales). We numbered humid, and shady localities (Rubio and Carrascal 1994; the scales from 10 to 60. All lizard specimens were Carretero et al. 2010; Rubio and Martín 2017). In many previously preserved in 70% ethanol. The specimens of these typical locations (but not in others; Fernández- are housed in the Spanish National Museum of Cardenete and García-Cardenete 2015; unpubl. data), Natural Sciences. We examined the scales under a the species tends not to share its