Seasonal patterns of daily light exposure in subterranean rodents

JANNETTI MG; FLÔRES DEFL; SILVA JTS; VALENTINUZZI VS; ODA GA

Bragança Paulista, Sao Paulo

Simposio; XIII Latin American Symposium on Chronobiology-LASC; 2015

Studies from our group with a subterranean rodent species Ctenomys aff. knighti (tuco-tucos) showed, through direct observation of animals in semi-natural enclosures, that they are synchronized by light/dark cycles in nature, despite presenting an irregular light exposure pattern. The aim of this work was to obtain automated data of tuco-tucos? daily light exposure patterns, using data-logger light sensors (Migrate Technology, UK) placed in collars. During summer (January) and winter (July) seasons, adult animals (n=13; 7 males and 6 females; 168g ± 42g) with light sensors were maintained individually in semi-natural enclosures (10×5×1m or 12×6×1,5m, both 1m deep) for seven days on average and, then, recaptured. Environmental conditions were also measured in a weather station (Onset, USA), along the days of experiment, to analyse acute modulations of environmental variables (temperature, humidity and wind conditions) on tuco tucos? surface activity. Automated data showed more accuracy than those from direct observations and detected more diverse light exposure patterns. In summer data, particularly, we obtained two-peak patterns that resembled skeleton photoperiod patterns. Comparison of summer and winter registers strongly indicates there are seasonal changes in these light exposure patterns. The diversity of patterns, within each season, is partially due to individual variability and also to the modulation by environmental variations.