title: Exposure to light enhances pre-adult fitness in two dark-dwelling sympatric species of ants.
abstract: BACKGROUND
  In insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/dark (LD) cycles to fine-tune a wide range of behavioral and physiological processes. To study the effect of environmental LD conditions on pre-adult fitness components, we used two dark-dwelling sympatric species of ants (the night active Camponotus compressus and the day active Camponotus paria), which normally develop underground and have fairly long pre-adult developmental time.
  
  
  RESULTS
  Our results suggest that ants develop fastest as pre-adults when maintained under constant light (LL), followed closely by 12:12 hr light/dark (LD), and then constant darkness (DD). While light exposure alters developmental rates of almost all stages of development, the overall pre-adult development in LL is speeded-up (relative to DD) by approximately 37% (34 days) in C. compressus and by approximately 35% (31 days) in C. paria. In LD too, development is faster (relative to DD) by approximately 29% (26 days) in C. compressus and by approximately 28% (25 days) in C. paria. Pre-adult viability of both species is also higher under LL and LD compared to DD. While pre-adult development time and viability is enhanced in LL and LD, clutch-size undergoes reduction, at least in C. compressus.
  
  
  CONCLUSIONS
  Exposure to light enhances pre-adult fitness in two dark-dwelling species of Camponotus by speeding-up development and by enhancing viability. This suggests that social ants use environmental light/dark cycles to modulate key life history traits such as pre-adult development time and viability.
authors.affiliation: Chronobiology Laboratory, Evolutionary and Organismal Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, PO, Box 6436, Jakkur, Bangalore 560 064, Karnataka, India. lone@jncasr.ac.in
authors.forename: Shahnaz Rahman
authors.initials: SR
authors.lastname: Lone
authors.forename: Vijay Kumar
authors.initials: VK
authors.lastname: Sharma
mesh_terms: D000818:Animals; D001000:Ants / Q000254:growth & development* / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects; D002940:Circadian Rhythm / Q000528:radiation effects; D052284:Clutch Size / Q000528:radiation effects; D003624:Darkness; D007814:Larva / Q000254:growth & development / Q000528:radiation effects; D008027:Light; D010063:Ovum / Q000166:cytology / Q000528:radiation effects; D011679:Pupa / Q000254:growth & development / Q000528:radiation effects; D013045:Species Specificity; D013997:Time Factors