THE SPECIES HISTORY, POPULATION GENETICS, AND BEHAVIORAL REPRODUCTIVE ISOLATING MECHANISMS OF TWO CHIHUAHUAN DESERT KATYDIDS (ORTHOPTERA: TETTIGONIIDAE) By BART J. KENSINGER Bachelor of Science in Biology University of Missouri Saint Louis, Missouri 2005 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY May, 2015 THE SPECIES HISTORY, POPULATION GENETICS, AND BEHAVIORAL REPRODUCTIVE ISOLATING MECHANISMS OF TWO CHIHUAHUAN DESERT KATYDIDS (ORTHOPTERA: TETTIGONIIDAE) Dissertation Approved: Dr. Barney Luttbeg Dissertation Advisor Dr. Johannes Schul Dr. Alex Ophir Dr. Michael Reiskind Outside Committee Member ii ACKNOWLEDGEMENTS I would like to thank all the people who have contributed to the completion of this dissertation both academically and personally. It has never been a solo venture. I first need to thank Barney Luttbeg for all his patience, guidance, and support over the last six years. He continually shows me new ways to approach data analysis and interpretation. Second, Johannes Schul has been an invaluable mentor in everything katydids and bioacoustics. The behavior work in this dissertation would not have been possible without him and the help of the terrific students in his lab. Alex Ophir and Michael Reiskind made significant contributions from the project design through the final edits. Ronald Van Den Bussche and Tony Echelle have both been keystones to the success of the molecular work included here, and I would especially like to thank Michael Schwemm and Justin Lack for the time they have put in with their technical expertise and lab protocols. I have had the good fortune to work with Ben DeWeese, Tyler Cullum, William Couch, and Arantxa Lasa over the years, all of whom have been outstanding undergraduate students. I wish them great success in their future endeavors. I would like to thank the U.S. National Park Service for protecting so many of the most pristine places on earth, and our nations most valuable natural resources. Our national parks are a constant source of inspiration to me as a biologist, and a person. Big Bend National Park has been a great help in granting collection permits, and allowing me to stay and work for many months over the years. On a personal level, I want to thank my greatest supporters: my mother Wendy and father Robert who have supported me in every way possible over the last six years. They continue to be the most caring parents a person could ask for. I also thank my sisters Sara and Chelsea, who are tremendous sources of encouragement. iii Acknowledgements reflect the views of the author and are not endorsed by committee members or Oklahoma State University. Name: BART JAMES KENSINGER Date of Degree: MAY, 2015 Title of Study: THE SPECIES HISTORY, POPULATION GENETICS, AND BEHAVIORAL REPRODUCTIVE ISOLATING MECHANISMS OF TWO CHIHUAHUAN DESERT KATYDIDS (ORTHOPTERA: TETTIGONIIDAE) Major Field: ZOOLOGY Abstract: Understanding the mechanisms and evolutionary processes that lead to reproductive isolation between populations is the major goal of speciation research. Here, I integrated approaches from phylogenetics, population genetics, and behavioral ecology to gain perspective on a behavioral isolating mechanism between two species of Chihuahuan desert katydids. Previously little was known about the genus Obolopteryx described over 100 years ago. In the first chapter I built the first molecular phylogeny from two mitochondrial DNA genes and compared my hypothesis to previous morphology-based hypotheses. In the second chapter I used Amplified Fragment Length Polymorphisms (AFLP) to compare total genetic similarity of allopatric and sympatric populations of the two focal species: O. oreoeca and O. brevihastata . I found substantial evidence that O. oreoeca was experiencing a gene-flow restriction between the allopatric population in the Chisos Mountains of the Big Bend National Park and the population in the Davis Mountains sympatric with O. brevihastata . I did not find equivalent support for differentiation between the two O. brevihastata populations. In the third chapter I explored the calling behavior of the males in both species, and the phonotactic responses of O. oreoeca females between allopatry and sympatry . I quantitatively described the calls of both species. I then tested whether various aspects of calls differed in allopatry and sympatry within each species. I tested for character displacement in call syllable durations of both species. I found that O. oreoeca populations showed no differences in most call features, but they did show character displacement in the syllable duration. Interestingly, while I failed to find character displacement in O. brevihastata's syllable duration, I found that other unexpected call features differ between their populations. Controlled experiments show that a high amplitude component of the male call is important for female O. oreoeca phonotaxis. Sympatric O. oreoeca females showed significantly decreased phonotactic responses to heterospecific calls compared to allopatric O. oreoeca females. This combined molecular and behavior data suggest a unique example of reinforcement in which females in a peripheral sky island population, sympatric with a non-sister species, have evolved strong heterospecific mating discrimination due to heterospecific competition for mates. iv TABLE OF CONTENTS Chapter Page I. INTRODUCTION .................................................................................................................. 1 Speciation background ......................................................................................................... 1 Species histories ................................................................................................................... 5 Population genetics .............................................................................................................. 6 Behavioral reproductive isolating barriers ........................................................................... 7 Katydids as a study system .................................................................................................. 8 Summary .............................................................................................................................. 9 References .......................................................................................................................... 11 II. A MOLECULAR PHYLOGENY FOR A NORTH AMERICAN PHANEROPTERINE KATYDID GENUS OBOLOPTERYX .............................................................................. 18 Abstract .............................................................................................................................. 18 Introduction ........................................................................................................................ 19 Methods ............................................................................................................................. 20 Sampling and DNA isolation ....................................................................................... 20 Sequencing and molecular analyses ............................................................................. 21 Results ............................................................................................................................... 22 Discussion ......................................................................................................................... 23 References ......................................................................................................................... 27 Figure Captions ................................................................................................................. 31 III. POPULATION STRUCTURE BETWEEN SKY ISLANDS IN A NARROWLY DISTRIBUTED CHIHUAHUAN DESERT KATYDID .......................... 33 Abstract ............................................................................................................................. 33 Introduction ....................................................................................................................... 34 Methods ............................................................................................................................. 35 Sampling ...................................................................................................................... 35 Molecular techniques ................................................................................................... 36 Analyses ....................................................................................................................... 37 Results ............................................................................................................................... 38 Discussion ......................................................................................................................... 39 References ......................................................................................................................... 44 Figure Captions ................................................................................................................... 4 v Chapter Page IV. INCREASED FEMALE MATING DISCRIMINATION AND CHARACTER DISPLACEMENT IN MALE CALLS IN SYMPATRIC CHIHUAHUAN DESERT KATYDIDS .....................................................................................................................