Influence of Habitat Structure and Prey Abundance on Occupancy and Abundance of Two Anole Ecomorphs, Anolis cristatellus and Anolis krugi, in Secondary Karst Forests in Northern Puerto Rico
Ecological studies strive to identify factors that explain patterns of species distribution and abundance. In lizards, competition and predation are major forces influencing distribution and abundance, but there is also increasing evidence pointing at the influence of habitat structure and prey abundance. Our work explored the latter further by quantifying the effects of vegetation and prey abundance on occupancy and abundance (i.e., estimated probability of detecting more than two individuals) of two sympatrically occurring species in the northern karst belt of Puerto Rico. We hypothesized that Anolis cristatellus would occur in trunk–ground substrates and Anolis krugi on grass–bush substrates according to their ecomorphological classification. We also hypothesized that prey abundance, a component of habitat quality, would have a positive and strong effect on occupancy and abundance. Anolis cristatellus exhibited high occupancy rates (>0.80), influenced by mid-story tree size. A. cristatellus abundance fluctuated over time, with highest probability of detecting two or more individuals in January–March and July–September when prey abundance transitioned from low to high levels. Occupancy of A. krugi was positively influenced by sapling density and prey abundance. Prey abundance exerted a stronger influence on occupancy, but its influence on abundance was negative and strong. Biological interactions and the type of understory substrates may explain the negative relationship. Our study supported predicted relationships between ecomorphology and habitat, but also showed that higher prey abundance may not always translate to higher local abundance. We shed light on these interactions, knowledge needed to advance anole conservation in the advent of land use and climate change.Abstract
Location of reserves, Mata de Platano (MPPR) and El Tallonal Private Reserves (ETPR), in the municipality of Arecibo in the northern karst belt of northern Puerto Rico (inset). Each reserve had two plots (0.25 ha each) and 15 quadrats per plot (0.004/ha each). White rectangles represent plots within the reserves delimited by yellow lines. The top two plots were within MPPR (M1, M2); the bottom two within ETPR (T1, T2).
Monthly estimates of the total number of arthropods captured per plot at the Mata de Platano (M1, M2) and El Tallonal (T1, T2) Private Reserves in the north-central karst region, Puerto Rico, 2012.
Occupancy probability (± SE) of A. cristatellus per quadrat as function of mid-story trees (diameter at breast height) in four-plots located at Mata de Platano and El Tallonal Private Reserves in the north-central karst region, 2012.
Probability (± SE) of encountering two or more individuals (R) per quadrat of A cristatellus as a function of sampling periods in four plots (M1, M2, T1, T2) located at Mata de Platano and El Tallonal Private Reserves in the north-central karst region, 2012.
Predicted occupancy probability of A. krugi per quadrat as a function of the average total prey abundance after controlling for the effect of sapling density in four plots (M1, M2, T1, T2) located at Mata de Platano and El Tallonal Private Reserves in the north-central karst region, 2012.
Probability (± SE) of encountering two or more individuals (abundance) of A. krugi per quadrat as a function of average total prey abundance in four plots (M1, M2, T1, T2) located at Mata de Platano and El Tallonal Private Reserves in the north-central karst region, 2012.
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