Date Thesis Awarded

5-2024

Access Type

Honors Thesis -- Open Access

Degree Name

Bachelors of Science (BS)

Department

Biology

Advisor

James Tumulty

Committee Members

John Swaddle

Helen Murphy

Rowan Lockwood

Abstract

How do species form and remain distinct from one another? These questions are central to the concept of speciation: the evolution and subsequent maintenance of new species through the divergence of populations. Research on speciation usually concentrates on how female mate choice prevents interspecies matings. Male-male competition also plays an important role in reproduction but is relatively understudied as a mechanism of speciation. The present study investigates how sexual selection via male-male competition contributes to speciation in two local “sibling” species of frogs: northern and southern cricket frogs. I conducted a field playback experiment to discern to what extent male northern cricket frogs (Acris crepitans) can recognize male calls of their own species versus those of the southern cricket frog (Acris gryllus) and modulate their aggressive responses accordingly. Analysis of the behavioral data shows that A. crepitans males respond aggressively to calls ranging from average calls of their own species to average calls of A. gryllus, notably excluding extreme A. gryllus calls. Ergo, recognition space does not equal signal space in A. crepitans males. Overall, anecdotal observations and analyses of results point towards the misinterpretation of some A. gryllus advertisement calls as conspecific aggressive signals, or possible character convergence. This research provides insight into the interplay between speciation and competition in two closely related species and evinces how signal recognition might evolve with respect to the evolution of the signals themselves.

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Available for download on Friday, May 09, 2025

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