Territoriality and Male-Biased Sexual Size Dimorphism in Argia Reclusa (Odonata: Zygoptera)

Territoriality and male-biased sexual size dimorphism in Argia reclusa (Odonata: Zygoptera) Rhainer Guillermo-Ferreira & Kleber Del-Claro acta ethologica ISSN 0873-9749 Volume 15 Number 1 acta ethol (2012) 15:101-105 DOI 10.1007/s10211-011-0114-9 1 23 Your article is protected by copyright and all rights are held exclusively by Springer- Verlag and ISPA. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self- archive your work, please use the accepted author’s version for posting to your own website or your institution’s repository. You may further deposit the accepted author’s version on a funder’s repository at a funder’s request, provided it is not made publicly available until 12 months after publication. 1 23 Author's personal copy acta ethol (2012) 15:101–105 DOI 10.1007/s10211-011-0114-9 Territoriality and male-biased sexual size dimorphism in Argia reclusa (Odonata: Zygoptera) Rhainer Guillermo-Ferreira & Kleber Del-Claro Received: 18 March 2011 /Revised: 27 September 2011 /Accepted: 3 October 2011 /Published online: 13 October 2011 # Springer-Verlag and ISPA 2011 Abstract In Odonata, many species present sexual size Keywords Argia . Dimorphism . Territoriality. Body size . dimorphism (SSD), which can be associated with male Mating success territoriality in Zygoptera. We hypothesized that in the territorial damselfly Argia reclusa, male–male competition can favor large males, and consequently, drive selection Introduction pressures to generate male-biased SSD. The study was performed at a small stream in southeastern Brazil. Males In territorial species, males with higher resource holding were marked, and we measured body size and assessed the potential (RHP; i.e., ability in acquiring and defending quality of territories. We tested if larger territorial males (a) territories) usually occupy the best reproductive sites (e.g., defended the best territories (those with more male Bart and Earnst 1999; Candolin and Voigt 2001). This ability intrusions and visiting females), (b) won more fights, and is often associated to phenotypic traits that best represent (c) mated more. Couples were collected and measured to RHP, such as body size (Parker 1974). In many insect show the occurrence of sexual size dimorphism. Results species, male body size is correlated with mating success indicated that males are larger than females, and that since larger males usually win more territorial fights and gain territorial males were larger than non-territorial males. access to females (Severinghaus et al. 1981; Borgia 1982; Larger territorial males won more fights and defended the Alcock 2000; Candolin and Voigt 2001; but see also Pie and best territories. There was no difference between the mating Del-Claro 2002). In territorial Odonata, generally larger success of large territorial and small non-territorial males. males have an advantage in fights for territories and/or Although our findings suggest that male territoriality may females (Tsubaki and Ono 1987;Sokolovskaetal.2000; play a significant role on the evolution of sexual size Switzer 2002; Serrano-Meneses et al. 2007). However, there dimorphism in A. reclusa, we suggest that other factors are cases where territorial and larger males have no should also be considered to explain the evolution of SSD advantage over non-territorial ones (Corbet 1999). in damselflies, since non-territorial males are also capable It has been suggested that territorial species present of acquiring mates. sexual size dimorphism (SSD), with males larger than females, while in non-territorial species, such pattern does not occur (Serrano-Meneses et al. 2008a). This hypothesis R. Guillermo-Ferreira is supported by evidences of selection acting through male– Departamento de Biologia, Faculdade de Filosofia, male competition in damselflies (e.g., Serrano-Meneses et Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, al. 2007). However, there are few studies on territorial Ribeirão Preto, SP, Brazil e-mail: [email protected] damselflies of the large family Coenagrionidae (e.g., Argia sedula, Corbet 1999; Argia apicalis, Bick and Bick 1965; K. Del-Claro (*) Pyrrhosoma nymphula, Gribbin and Thompson 1991; and Instituto de Biologia-Campus Umuarama, L.E.C.I., Ennallagma civile, Corbet 1999). Additionally, there are Universidade Federal de Uberlândia, Mail Box 593, CEP 38400-902, Uberlândia, MG, Brazil few empirical data on the relationship between male–male e-mail: [email protected] competition and SSD in territorial damselflies. Author's personal copy 102 acta ethol (2012) 15:101–105 In the present study with the territorial damselfly Argia out of the area. These contest usually lasted around 10 s. reclusa Selys 1865 (Coenagrionidae), we tested whether The male that perched several meters away from the male body size influences on male–male competition, contested territory was considered the loser and the male resulting in male-biased SSD. We hypothesized that larger that returned and perched on the contested territory, the males would win more fights, mate more, and defend winner. This method is often used to determine winners and higher-quality territories. Territory quality is usually mea- losers of territorial fights in damselflies (e.g., Contreras- sured as the attractiveness to females and to rival males in Garduno et al. 2008). odonates (Tsubaki and Ono 1987; Koenig 1990; Switzer To address if non-territorial males are smaller than 2002) and by the presence of more and/or better oviposition territorial males, before observations, we captured, mea- resources (e.g., aquatic plants, submerged substrate, and sured their body size, and marked both territorial and non- aerial stems, see Guillermo-Ferreira and Del-Claro 2011). territorial males. Territorial males were considered to be We also hypothesized that territorial males would be larger those males that remained on the stream borders defending than non-territorial males, since smaller males usually adopt and fighting for territories. Non-territorial males were those alternative mating tactics, assuming a non-territorial behavior males captured on the surrounding vegetation that were and pursuing females before they arrive at the reproductive never seen defending a territory. Non-territorial males were sites instead of defending a territory (e.g., Alcock and Houston never seen fighting and only approached the stream when 1996, Watanabe and Taguchi 1990; Raihani et al. 2008). The they were in tandem with a female. The body size of confirmation of these hypotheses could suggest that selection territorial and non-territorial males was then compared. To favors male body size and that territoriality may be an evidence sexual size dimorphism, we compared the body influencing factor of SSD. size of marked males and ten females collected at the site. From June to October 2008, we made additional 100 h of behavioral observations (all occurrence sample was done in Materials and methods 25 days between 10:00 and 14:00 hours), capturing and marking males to determine their body size and mating The study was conducted in the Laureano stream located in tactic. To answer if male body size and mating tactic (i.e., the municipality of Ribeirão Preto (21°9′58″ S, 47°51′51″ territorial or non-territorial) is correlated with mating W). We used an area of 8 m along the stream borders where success, we identified the male in every mating or preliminary observations showed that A. reclusa males ovipositing couple during the whole study period (from defended territories. Surveys along the stream showed that May to October 2008, 130 h of observation). This was males clustered in this specific area. In even days between 5 possible because mating and ovipositions lasted more than and 14 May 2008, between 10:00 and 14:00 hours (when 1 h and occurred in a limited space. sexual activities take place), each male was caught, marked Statistical analyses showed the data were normal on the right forewing, and had his body length measured distributed (Kolmogorov–Smirnov test; d=0.16; p>0.2). dorsally excluding appendages (in centimeters) with a Thus, we used Student’s t tests to compare the body size of digital caliper (0.01 mm). males and females. To compare the body size of territorial Assuming that there would be more intense competition and non-territorial males, we used analysis of variance for high-quality territories than low-quality territories and (ANOVA) with the territorial status and period of study as that females would oviposit on the territories with best independent factors. The period of study was divided in resources, we conducted 30 h of “all occurrence sample” two categories: (1) May and (2) June to October. This behavioral observations (sensu Altmman 1974) and quan- test was needed because males collected in (1) were tified the following variables to determinate the quality of larger (x=3.54±0.04 cm; N=20) than males collected in territories: (a) the number of ovipositions in each territory (2) (x=3.42±0.04 cm; N=10) (ANOVA, F=4.86; df=1; and (b) the number of male intrusions in each territory. p=0.03), showing seasonal variations on male body size, Every 15 min, an “instantaneous shot sampling” (sensu which is common in damselflies (e.g., Córdoba Aguilar Altmman 1974) was done to take note of which male was 2009). The Fisher’s exact test was used to test if territorial defending each territory. Territory quality was then corre- males mated more frequently than non-territorial males. To lated with the resident male body size, considered to be the compare the body size of winners and losers of territorial male that spent most time defending the territory during the fights, we used the paired t test. We did not consider the 30 h of observations. study period in this test because these data were collected in To answer if larger males win more fights, we identified the same period.

Load more