Whispering to the Deaf: Communication by a Frog without External Vocal Sac or Tympanum in Noisy Environments

Atelopus franciscus is a diurnal bufonid frog that lives in South-American tropical rain forests. As in many other frogs, males produce calls to defend their territories and attract females. However, this species is a so-called “earless” frog lacking an external tympanum and is thus anatomically deaf. Moreover, A. franciscus has no external vocal sac and lives in a sound constraining environment along river banks where it competes with other calling frogs. Despite these constraints, male A. franciscus reply acoustically to the calls of conspecifics in the field. To resolve this apparent paradox, we studied the vocal apparatus and middle-ear, analysed signal content of the calls, examined sound and signal content propagation in its natural habitat, and performed playback experiments. We show that A. franciscus males can produce only low intensity calls that propagate a short distance (<8 m) as a result of the lack of an external vocal sac. The species-specific coding of the signal is based on the pulse duration, providing a simple coding that is efficient as it allows discrimination from calls of sympatric frogs. Moreover, the signal is redundant and consequently adapted to noisy environments. As such a coding system can be efficient only at short-range, territory holders established themselves at short distances from each other. Finally, we show that the middle-ear of A. franciscus does not present any particular adaptations to compensate for the lack of an external tympanum, suggesting the existence of extra-tympanic pathways for sound propagation

Multi-unit franchising strategies: a real options logic

Theories of the firm so far applied to explain franchising struggle to enlighten its operational extensions, such as multi-unit franchise strategies. The corporate decision to grow via multiple franchising has not been yet analyzed with a view to accounting for how the flexibility to franchise or not (vis-a`-vis the rigidity of investing into new own outlets), as uncertain market circumstances warrant, can drive performance. In this study, we seek to fill the gap by proposing a theoretical framework and empirically investigating about the real options that underlie multiunit franchise strategies. Three are the key contributions to the franchising literature. First, an options-based classification of multi-unit franchise strategies is advanced in an effort to better explicate franchising and its performance consequences. Second, evidence drawn from the U.S. franchising industry is provided so as to both support classical findings on franchising and highlight the key source of extra value brought in by optionality associated with multi-unit arrangements and their impact on network performance. Third, ‘‘theoretical diversity’’ on franchising (Combs et al. In: J Manage 30:907–931, 2004) is enlarged by responding to the recent call for researchers to deliver complementary insights into what makes franchising work applying for the first time the real options theory to franchising. Implications of our findings for researchers, managers and policy-makers are discussed