Abstract
ABSTRACT Microlophus is a lizard genus of South-America which has many species with sexual size dimorphism. An ecologicalstudy was performed on M. atacamensis, a species inhabiting the intertidal zone of the coast of northern Chile. Thefollowing questions were addressed: (1) does M. atacamensis exhibit sexual dimorphism? (2) do individuals of differentage and sex segregate spatially? (3) do individuals of different age and sex use different type of microhabitat? and (4)do individuals of different sexes exhibit differences in thermoregulatory characteristics? The study was conducted indifferent localities from northern Chile, which include two types of rocky systems used by this species, a high and alow type. At the moment of lizard capture, type of microhabitat, height of perch, body, air and substrate temperatures,were recorded. Individuals were then measured and weighted, and separated by age class and sex. Results indicate thatthis species exhibits sexual dimorphism, males being larger. There were no intersexual differences in microhabitat usedand height of perch in the high type system, although adults and subadults were spatially segregated from juveniles. Inthe low type system adult females shared microhabitat with juveniles, a probable consequence of behaviors related tothe burying of eggs. There were no differences between sexes in thermal characteristics, and body temperature of lizardsshowed independence from external thermal conditions.Key words: Tropiduridae, Microlophus atacamensis , sexual dimorphism, thermoregulation, spatial segregation,Chile.
Highlights
In most animal groups, sexual differences in morphological characters, in body size, is a common phenomenon
Previous studies suggest that M. atacamensis shows sexual size dimorphism and that individuals might spatially segregate by age class and sex (DonosoBarros 1966, Flores et al 1977, Ortiz 1980a, Heisig 1993); males use microhabitats with higher availability of sunny perches and closer to food resources, than do females (Heisig 1993)
To clarify if previous suggestions on some ecological characteristics of M. atacamensis (Donoso-Barros 1966, Flores et al 1977, Ortiz 1980a, Heisig 1993) have support, we addressed the following questions: (1) does M. atacamensis have sexual dimorphism? (2) do individuals of different age and sex segregate spatially? (3) do individuals of different age and sex use different types of microhabitats? and (4) do individuals of different sex exhibit differences in thermoregulatory characteristics?
Summary
Sexual differences in morphological characters (sexual dimorphism), in body size, is a common phenomenon. Previous studies suggest that M. atacamensis shows sexual size dimorphism and that individuals might spatially segregate by age class and sex (DonosoBarros 1966, Flores et al 1977, Ortiz 1980a, Heisig 1993); males use microhabitats with higher availability of sunny perches and closer to food resources, than do females (Heisig 1993). Given that in the intertidal zone where M. atacamensis is found (Donoso-Barros 1948, 1966, Heisig 1993), is a low temperature microhabitat (Báez & Cortés 1990), the sexual spatial segregation may be reflected in differences in thermoregulatory strategy. To clarify if previous suggestions on some ecological characteristics of M. atacamensis (Donoso-Barros 1966, Flores et al 1977, Ortiz 1980a, Heisig 1993) have support, we addressed the following questions: (1) does M. atacamensis have sexual dimorphism? (2) do individuals of different age and sex segregate spatially? (3) do individuals of different age and sex use different types of microhabitats? and (4) do individuals of different sex exhibit differences in thermoregulatory characteristics?
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