Processes influencing community structure in Anolis lizards (Dactyloidae) from Ecuador

Submission note: A thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Life Sciences, Ecology, Environment and Evolution, College of Science, Health and Engineering, La Trobe University, Bundoora.

Thesis with publications.

Species aggregations within communities can be influenced by a variety of processes, which operate over different spatial and temporal scales. They can physiologically respond to local ambient variation, spacially segregate by selecting suitable ecological conditions, or by using behavioural signals, delimit their territories to successfully cohabit. I tested the capacity of such processes at different scales to affect the cooccurrence of Anolis lizards from Ecuador. Firstly, I investigated the influence of ambient temperature variation in nocturnal perch site selection and local segregation within sympatric communities across species distributions. Secondly, to predict co-occurrence, I examined simultaneously the influence of broad environmental envelopes, narrowing toward regional and local structure to fine-scale site selection. I also considered the role of neutral processes, by including phylogenetic relatedness, and assess the importance of morphology in niche partitioning over different spatial scales. In the second half of my thesis, I focus on differences in communicative signals, a more specific level of segregation. I analysed the colour of dewlaps and surrounding plants to quantify the detectability of the signal in a given habitat, and quantified variation in the dynamic properties of display movements. Two hypotheses were examined to evaluate the role of visual signalling in communities. The species recognition hypothesis was tested using sympatric species, whereby sympatric species were predicted to differ in signal structure (colour or motion), to reinforce species identity. The local adaptation hypothesis was tested in allopatric populations of species occuring [i.e. occurring] in different environments. I predicted high signal detectability in their own habitats, and an influence of habitat structure on signalling variation across species’ ranges. I integrate my results to quantify the contribution of ecological variation and behavioural differences, at intra-specific and inter specific levels, to explain community structure. First, I found variation in Anolis thermal strategies, mainly occurring at high elevations, and in relationship with retreat site utilization. Further, I detected environmental variation as an indicator of species co-occurrence, which is further predicted by local habitat partitions due to variation across forest types and habitat characteristics. In addition, the evolutionary history of the group predicted highest probability of co-occurrence for distantly related species; however, it is not applied ix across all assemblages. No influence of morphology was observed on species cooccurrence. Furthermore, I found evidence for intra-specific signalling variation, however no effect of congeners was supported. I suggest signalling is highly important for species recognition, and it seems to be influenced also by variation of the forest type. These results suggest that local adaptation and species recognition act as drivers of animal communication toward promoting effective detectability across the landscape. However, I am unable to discount several alternative hypotheses that remain to be tested. My study utilized an integrative perspective to predict species co-occurrence to provide a full picture of the ecology of several mainland Anolis. Further, I provided ecological and behavioural information for several species, for which no information has been previously reported. Furthermore, this research represents the first effort to analyse the signal of any mainland Anolis from South America, analysing the motion of the display and also the colour of the dewlap simultaneously.