RESUMO
Home range is defined as the area within which an individual moves to acquire resources necessary to increase their fitness and may vary inter and intra-specifically with biotic and abiotic factors. This study details the home range of the parthenogenic lizard, Aspidoscelis cozumela, an active forager microendemic to Cozumel Island, México, with high preference for open sand beaches. The home range of A. cozumela was compared with other species of Aspidoscelis (gonochoric and parthenogenetic) and other lizards that occupy coastal habitats. Furthermore, the biotic and abiotic factors that may influence home range were analyzed. This study was conducted in the beach located on the East side of the island (area of 4,000 M2) that is composed primarily of halophyte vegetation with high levels of sunlight. From 1999 to 2001, nine samples were taken which included the dry, rainy, "nortes", and breeding seasons. During each sampling, capture-mark-recapture techniques were conducted and the date, time of day, and snout-vent length (SVL) were recorded to the nearest millimeter. Individuals were located in the study area using a bi-coordinate reference using 10 x 10 m subdivisions of the habitat. Home range and home range overlap were calculated using the convex polygon method in McPaal and home range/SVL correlation was tested using Pearson's correlation. To calculate females home range, three or more recaptures were considered. A total of 20 home ranges that averaged 45.1 ± 14.0 m2 were obtained and no correlation between SVL and home range size was detected (p = 0.9229, n = 20). However, removing individuals with outlier home ranges (females with home ranges > 100 m2, n = 2) resulted in a positive correlation with SVL (r = 0.61, p = 0.0072, n = 18). A 22.9 ± 5.7% overlap in home range was also detected. The small home range of A. cozumela represents the smallest home range within the Aspidoscelis genus recorded to date (including both parthenogenetic and gonochoric species) and contrasts the theoretical predictions of broad home ranges for widely foraging species. Thermoregulatory benefits and a high population density may explain the small home range of A. cozumela. Although this species is highly adapted to the environmental conditions present on the open sand beaches, anthropogenic effects on these habitats by the development of tourism infrastructure may jeopardize their existence on Cozumel Island.
Assuntos
Ecossistema , Comportamento de Retorno ao Território Vital/fisiologia , Lagartos/fisiologia , Animais , Feminino , Lagartos/classificação , Masculino , México , Partenogênese , Densidade Demográfica , Estações do AnoRESUMO
Home range is defined as the area within which an individual moves to acquire resources necessary to increase their fitness and may vary inter and intra-specifically with biotic and abiotic factors. This study details the home range of the parthenogenic lizard, Aspidoscelis cozumela,an active forager microendemic to Cozumel Island, México, with high preference for open sand beaches. The home range of A. cozumelawas compared with other species of Aspidoscelis(gonochoric and parthenogenetic) and other lizards that occupy coastal habitats. Furthermore, the biotic and abiotic factors that may influence home range were analyzed. This study was conducted in the beach located on the East side of the island (area of 4 000 m2) that is composed primarily of halophyte vegetation with high levels of sunlight. From 1999 to 2001, nine samples were taken which included the dry, rainy, "nortes", and breeding seasons. During each sampling, capture-mark-recapture techniques were conducted and the date, time of day, and snout-vent length (SVL) were recorded to the nearest millimeter. Individuals were located in the study area using a bi-coordinate reference using 10 x 10 m subdivisions of the habitat. Home range and home range overlap were calculated using the convex polygon method in McPaal and home range/SVL correlation was tested using Pearson's correlation. To calculate females home range, three or more recaptures were considered. A total of 20 home ranges that averaged 45.1 ± 14.0 m2 were obtained and no correlation between SVL and home range size was detected (p = 0.9229, n = 20). However, removing individuals with outlier home ranges (females with home ranges > 100 m2, n = 2) resulted in a positive correlation with SVL (r = 0.61, p = 0.0072, n = 18). A 22.9 ± 5.7% overlap in home range was also detected. The small home range of A. cozumelarepresents the smallest home range within the Aspidoscelisgenus recorded to date (including both parthenogenetic and gonochoric species) and contrasts the theoretical predictions of broad home ranges for widely foraging species. Thermoregulatory benefits and a high population density may explain the small home range of A. cozumela.Although this species is highly adapted to the environmental conditions present on the open sand beaches, anthropogenic effects on these habitats by the development of tourism infrastructure may jeopardize their existence on Cozumel Island.
El ámbito hogareño es el área dentro de la cual un individuo se mueve para adquirir recursos que incrementen su supervivencia. El ámbito hogareño puede variar, intra e interespecíficamente, por factores bióticos y abióticos. En este trabajo se estudió el ámbito hogareño de la lagartija partenogenética Aspidoscelis cozumela,una especie de forrajeo amplio, con alta preferencia por las playas y microendémica de Isla Cozumel, México. El ámbito hogareño de A. cozumelase comparó con otras especies de Aspidoscelis(gonocóricas y partenogenéticas) y con otras lagartijas que ocupan hábitats costeros. Además, se discuten los factores bióticos y abióticos que lo moldean. La zona de estudio fue una playa (con un área de 4 000 m2), que se encuentra al Este de la isla y que presenta vegetación halófita (expuesta a altos niveles de insolación). De 1999 al 2001 se realizaron nueve censos que cubrieron la época de sequía, de lluvias y la época de "nortes" de la zona y la temporada de reproducción de A. cozumela.Durante cada censo, se realizó captura-marcaje-recaptura y se registró: fecha, hora del día, longitud hocico-cloaca (LHC) al milímetro más cercano. Los individuos fueron ubicados en el área de estudio por bi-coordenadas usando estacas como referencia. El ámbito hogareño se calculó con el método del polígono convexo con el programa McPaal, adicional-mente se calculó el solapamiento del ámbito hogareño. Se relacionó la LHC con el ámbito hogareño. Para el cálculo del ámbito hogareño se consideraron las hembras con tres o más recapturas. Se obtuvieron 20 ámbitos hogareños, que promediaron 45.1 ± 14.0 m2. No se encontró relación de la LHC con el ámbito hogareño (p = 0.9229, n = 20). Sin embargo, un análisis que excluyó los individuos con los ámbitos hogareños extremos, mostró que el ámbito hogareño de A. cozumelase relacionó de manera positiva con la LHC (p = 0.0072, n = 18), las hembras más grandes tuvieron ámbitos hogareños más amplios. El solapamiento del ámbito hogareño fue de 22.9 ± 5.7%. El ámbito hogareño de A. cozumelaes el más pequeño que se ha documentado en el género Aspidoscelis(incluyendo especies partenoge-néticas y gonocóricas) y se contrapone con las predicciones teóricas que establecen ámbitos hogareños amplios para especies de forrajeo amplio. Beneficios térmicos y una elevada densidad poblacional pueden explicar la marcada residencia en las playas y ámbito hogareño reducido de A. cozumela.La lagartija partenogenética A. cozumelaestá bien adaptada a las condiciones ambientales en las playas, sin embargo las afectaciones severas en las playas por el desarrollo de la infraestructura turística pueden poner en riesgo su existencia en Isla Cozumel.