How grasshoppers respond to road noise: developmental plasticity and population differentiation in acoustic signalling

Abstract

Summary1. Increasing levels of anthropogenic noise have the potential to mask signals of acoustically communicating species in their natural habitats. Animals in noise-polluted habitats typically adjust their signals away from high background noise levels to ensure successful signal transmission under challenging environmental conditions. Earlier we demonstrated that male Chorthippus biguttulus grasshoppers from roadside habitats produce courtship signals with elevated frequency components compared to conspecifics from non-roadside habitats.2. Here, we use a common garden approach to study the mechanisms underlying this response. We transferred grasshopper nymphs from seven roadside as well as five non-roadside habitats to the laboratory to rear half of them under noisy and the other half under quiet conditions in a full factorial two-by-two design. Courtship songs of adult males were later recorded under standardized quiet conditions. 3. Males exposed to road noise as nymphs produced signals with higher frequency components compared to males reared under quiet conditions, indicating developmental plasticity as a mechanism underlying the signal adjustment to anthropogenic noise in grasshoppers. 4. In addition, males originating from roadside habitats produced signals with higher frequency components and an increased syllable to pause ratio -a sexually selected signal trait -compared to males from non-roadside habitats. 5. Our results demonstrate for the first time that developmental plasticity may play an important role in song trait modifications in response to anthropogenic noise. Furthermore, they suggest that multiple roadside populations may have diverged in parallel, possibly in response to selection for minimizing signal masking by road noise.

Sexy voices – no choices: male song in noise fails to attract females

“…Anthropogenic noise has the potential to reduce population sizes and species diversity of birds (Barber et al, 2010). Although, to our knowledge, no study has investigated how noise affects insect diversity, our study, together with previous work on signalling male crickets (Lampe, Reinhold, & Schmoll, 2014;Lampe, Schmoll, Franzke, & Reinhold, 2012) and cicadas (Shieh, Liang, Chen, Loa, & Liao, 2012), suggests similar effects on insects. Invertebrates are a crucial component of food webs and fulfil many ecosystem services, such as decomposition, nutrient release and pollination (Morley, Jones, & Radford, 2013).…”

Decision making and preferences for acoustic signals in choice situations by female crickets

“…Therefore, the quality of a given signal is not necessarily positively correlated with intensity. In addition, further sound sources such as abiotic (Brumm and Slabbekoorn, 2005;Reichert and Ronacher, 2015) or even anthropogenic noise (Lampe et al, 2012(Lampe et al, , 2014Schmidt et al, 2014) may impede signal representation and recognition. Crickets, bushcrickets and grasshoppers are known to employ several processing tools to reduce the detrimental effects of masking and noise (Einhäupl et al, 2011;Schmidt and Römer, 2011;Neuhofer and Ronacher, 2012;Hildebrandt et al, 2015), most prominently by forward masking, selective attention, formation of acoustic hemispheres and stream segregation (Pollack, 1986;Schul and Sheridan, 2006;Triblehorn and Schul, 2009;Schmidt and Römer, 2011).…”

Biomechanical control of vocal plasticity in an echolocating bat

“…insects, Lampe et al, 2014;frogs, Parris et al, 2009;birds, Nemeth et al, 2013;mammals, Bates et al, 2008). For instance, in urban areas where noise is dominated by low-frequency components, birds sing at a higher pitch, which reduces masking by shifting their songs to a frequency range where background noise contains less energy (Slabbekoorn, 2013).…”