Is richness of local tropical butterfly faunas underestimated? Perspectives gained from biases in transect observations(In English)

摘要

We use cumulative species records of butterflies from transects collected locally at Calumpang Lejos (Indang, Cavite ) on Luzon , Philippines , to test whether inventories of taxa underestimate local species richness and diversity. No limit emerges in species cumulative curves despite 457 transects carried out over two years, including 340 hours of observation. Jackknife estimates, biased recording, and local variation in richness, relative abundances and diversity associated with contrasts in biotopes, all support the notion of the richness of local butterfly faunas being underestimated. Bias was recorded locally in transect records for abundance and colour pattern. This bias was mirrored for find dates and dates of scientific naming for the same species, as well for all species found on Luzon and throughout the Philippines and extended to butterfly size. Less abundant, smaller and duller species are discovered significantly later. Bias is taxonomically based; Hesperiidae and Lycaenidae have significantly later find dates and scientific naming dates than Papilionidae, Pieridae and Nymphalidae and are also significantly less abundant, smaller and duller. Biased recording may be exacerbated by the reinforcement of physical apparency: species with less apparent wing patterns tend to be smaller. It was found that rarer species were significantly smaller and duller for Luzon and at Calumpang Lejos. As bias for the local transects involves Lycaenidae but not Hesperiidae, it is suggested that bias, in this study, is caused by under-recording of canopy species. The implications for faunal inventories of other organisms and conservation of tropical butterflies are discussed; there is a need for new techniques, which account for bias, to provide suitable estimates of species richness from faunal samples [ A cta Zoologica Sinica 51(2): 237–250, 2005].