Behaviour and ecology of mating in the jumping spider Servaea incana (Araneae: Salticidae) Vivian Méndez Álvarez, BSc, MSc Macquarie University Department of Biological Sciences March 2015 This thesis is presented for the degree of Doctor of Philosophy Table of Contents Abstract…………………………………………………………………………..……..vi Statement of Candidate………………………………………………………………viii Acknowledgements………………………………………………………………..........ix Chapter One: General Introduction………………………………………...……........1 Research objectives…………………………………………………….……….6 Thesis organisation………………………………………...……….….………..7 References………………………………………………………………….……9 Chapter Two: Natural history and display behaviour of Servaea incana, a common and widespread Australian jumping spider (Araneae, Salticidae)………………....17 Abstract………………………………………..……………………………….17 Introduction……………………………………………………..…………..…19 Methods…………………………………………………..………………….....22 Observations…………………………………………………………..……….27 Discussion………………………………………………………………………77 Acknowledgements………………………………………………….…...…….83 References……………………………………………….……………..…........83 Chapter Three: Seasonal variation in sexual opportunities of Servaea incana jumping spiders………………………………………………………………………..92 iii Abstract………………………………………………………..……………….92 Introduction……………………………………………..…..………………....94 Materials and Methods…………………………………..……………..……..97 Results………………………………………………………………….............99 Discussion……………………………………………………..........................105 Acknowledgements…………………………………………………………...113 References………………………………………………….……………........114 Chapter Four: Mating-induced sexual inhibition in a jumping spider: a fast acting and long lasting effect……………………………..…………………………………120 Abstract…………………………………………………..…………………...120 Introduction………………………………………………..…………………122 Materials and Methods………………………………....…………………....126 Results………………………………………..………….……………………132 Discussion………………………………………………..…………………....137 Acknowledgements…………………………………….…..…………………143 References……………………………….……………………………………144 Chapter Five: Sexual receptivity in female spiders: a review ......................……...155 Abstract……………………………………….……………………………....155 Introduction………………………………………………..…………………157 Diverse mating patterns in spiders………………….……………………....159 iv The mechanisms of mating-induced sexual inhibition …….……………....180 Acknowledgements…………………………….…………..………………....183 References……………………………………….……………………..……..183 Chapter Six: General Discussion……………………………………........................197 References………………………………………………...………………..…208 v Abstract Female sexual receptivity has been studied in great detail in insects, but very little is known about female sexual receptivity in spiders. I studied female sexual receptivity and associated life history traits in Servaea incana (Salticidae), a common jumping spider of temperate Australia. S. incana inhabit the trunks of eucalypt trees, where they build retreats and nests under loose pieces of bark. The display repertoire of S. incana is typical of salticids, although relatively simple compared to the displays of some of Servaea’s closest relatives. Context-dependent courtship versatility was evident in S. incana although not as pronounced as in many other jumping spiders. Adult males cohabit with subadult females at retreats, copulating shortly after females mature. Cohabiting pairs tended to assort by size and this may reflect size-dependent outcome of contests between males for access to larger females. In a population where virgin females were most abundant at the beginning of the mating season, males of S. incana were found to mature earlier than females (protandry). I report for the first time in a jumping spider the number of copulations a female had over her entire life, and the occurrence and latency of sexual inhibition in this species. Mating status was found to have a potent effect on receptivity. Virgin females were highly receptive, but after only a single mating became aggressive towards males. Context was also important; virgin females in the open encountered more males before mating than was the case if they were in a retreat. However, after an initial mating, females in the open required a fewer number of exposures to males prior to remating, compared to females in retreats. Mating-induced sexual inhibition of females appears to vi have consequences for life history; protandry and cohabitation likely increases a male's access to receptive virgin females. The findings of empirical studies of S. incana are placed in the broader literature through a detailed review of mating patterns of female spiders in an ecological context, and likely mechanisms underpinning mating-induced sexual inhibition. Although little explicit research exists on receptivity and the mechanism that induces sexual inhibition in spiders, a range of studies was found that included species that, like S. incana, tend to copulate only once in their life (e.g., many Lycosidae) and species that mate readily even after many copulations (e.g., many Nephiliidae). Variation is also very common within species as in S. incana, with some females mating only once and others mating repeatedly. Here we present the first study on mating-induced sexual inhibition during the entire life of a female spider. We used the observations on female remating to understand better the phenology, natural history and mating decisions of males and females in a population. vii Statement of Candidate I certify that this thesis entitled “Behaviour and ecology of mating in the jumping spider Servaea incana (Araneae: Salticidae)” has not previously been submitted for a degree nor has it been submitted as part of requirement for a degree to any other university or institution other than Macquarie University. I also certify that the thesis is an original piece of research and it has been written by me. Any help and assistance that I have received in my research work and the preparation of the thesis itself have been appropriately acknowledged. In addition, I certify that all information sources and literature used are indicated in the thesis. This thesis was not subject to approval by the Macquarie University Ethics review Committee since the organism studied is an invertebrate, the jumping spider Servaea incana. Vivian Mendez (Student ID 40488020) March 2015 viii Acknowledgements Over the past three and a half years I have been supported by many people and I feel in debt to all of them. First, I want to thank my supervisor, Phil Taylor. Phil has not only been an excellent supervisor, but also a good friend that was always quick to help me and my family and for which we are very grateful. All the people (past and present) participating in Phil Taylor’s lab have also contributed in their own special way to the completion of my PhD, and I thank them. Special recognition goes to Rowan McGinley, I thank you for all your help, cheerful attitude during a long year of field work and for providing the front page photo of this thesis. I also thank Rowan’s parents, Roger and Marcia, for the invitations to their house; they made us feel right at home. I consider myself fortunate for the special friends I have made in Sydney. Thank you Cata, Randol, Maria, Alex, Dona Olga, Bibiana, Miguel and Michaela for making us feel a part of your families, and feeding us with your amazing cuisine. You are a wonderful family and always made us feel loved and in good company. Many thanks to my friends: Rocio, Alejandra, Martha, Vivian, Natalia, Caty, Ruth, Lis, Karla, Alvaro, Laura, Anita, Luis and Jeani. To my family in Costa Rica, thank you for being so supportive. Special thanks to my mum, Ana Maria, and my mother-in-law, Flor Alicia, for making the long trip to ix Australia to help take care of my son, Santi, precisely when I needed them most. Also, I wish to thank my sister, my father, my brother in law, my nephew and nieces for taking care of Santi , which allowed me time to focus on my research. And finally, I am very grateful for the loving support of my partner, Carlos Porras, and my son, Santiago, who have been integral members of this Ph.D. adventure. Carlos, I am grateful for your love, kindness and understanding throughout this process. You and Santi have given me a very beautiful life. x Chapter One: General Introduction For many years after Darwin (1871) first coined the term, the study of 'sexual selection' has focused almost entirely on precopulatory events, specifically (1) the elaborate ornamentation and courtship routines of male animals that may be used by females to assess their quality as mates and (2) weapons and displays used by males to resolve contests over access to females as a mating resource (Andersson 1994). Mating is of course a crucial step toward reproduction in most sexually reproducing species, but it is important to also bear in mind that other steps remain before the act of mating can yield a functional offspring. In recent decades we have gained greatly increased appreciation that males and females both commonly possess post copulatory mechanisms that are important in determining which male's sperm fertilizes a female's eggs (Parker 1984 and Eberhard 1996). Both female choice and male-male competition persist beyond copulation. Females may mate with more than one male and then choose which male's sperm to use for fertilizations ('cryptic female choice', sensu Eberhard 1996). Also, males often have adaptations that function in biasing fertilizations in their favour in females that accept more than one male as a mate ('sperm competition', see Parker 1998, Simmons 2001). There are several benefits