Vibroscape analysis reveals acoustic niche overlap and plastic alteration of vibratory courtship signals in ground-dwelling wolf spiders

Soundscape ecology has enabled researchers to investigate natural
interactions among biotic and abiotic sounds as well as their influence on
local animals. To expand the scope of soundscape ecology to encompass
substrate-borne vibrations (i.e. vibroscapes), we developed methods for
recording and analyzing sounds produced by ground-dwelling arthropods to
characterize the vibroscape of a deciduous forest floor using inexpensive
contact microphone arrays followed by automated sound filtering and
detection in large audio datasets. Through the collected data, we tested
the hypothesis that closely related species of Schizocosa wolf spider
partition their acoustic niche. In contrast to previous studies on
acoustic niche partitioning, two closely related species - S. stridulans
and S. uetzi - showed high acoustic niche overlap across space, time,
and/or signal structure. Finally, we examined whether substrate-borne
noise, including anthropogenic noise (e.g., airplanes) and heterospecific
signals, promotes behavioral plasticity in signaling behavior to reduce
the risk of signal interference. We found that all three focal Schizocosa
species increased the dominant frequency of their vibratory courtship
signals in noisier signaling environments. Also, S. stridulans males
displayed increased vibratory signal complexity with an increased
abundance of S. uetzi, their sister species with which they are highly
overlapped in the acoustic niche.