2.1.1 Study Sites
Dung beetles examined in this study were sampled in Singapore and Peninsular Malaysia. Figure 1 depicts a map of all sampling sites, and a full list coordinates are appended in a supplement to the main manuscript (Appendix 1: Table S1). Sampling in Singapore spanned over fifteen months from August 2018 to February 2018 and May 2019 to December 2019. Specimens from Malaysia were sampled across four sites, Perak, Gombak, Kenyir and Langkawi, from August to November 2016, and July 2019. Beetles from sites A, B, C and D were pooled because these sites were part of a continuous stretch of forest in the central region of Singapore. Sites G, H and I are mainland Malaysia sites that are closer to one another than they are from the others and they were pooled due to sample limitations. Furthermore, based on mitochondrial haplotypes (Appendix 2), genetic variation of Onthophagusbabirussa was panmictic and samples from sites G, H and I were genetically similar to each other, further justifying our grouping of the three sites as a representation of mainland Peninsular Malaysia. Site E (Pulau Ubin) and F (Langkawi) were both island populations, separated from mainland Singapore and Peninsular Malaysia respectively. Potential limitations from pooling the population were also taken into account during statistical analyses in section 2.4.