International Society for Behavioral Ecology Congress at Melbourne, Australia

Relationships between female-female competition and female mate choice in the freshwater goby Rhinogobius flumineus

 

TAKAHASHI Daisuke and SAKOI Rio (Kobe College)

 

Materials and Methods

 

Subject fish

              The genus Rhinogobius (Gobiidae) is widely distributed in freshwaters from East to Southeast Asia, and consists of more than 85 species. The Rhinogobius fishes inhabit almost all freshwater regions within Japan, and have been resolved into at least 18 species (Yamazaki et al. 2015). The species of this genus include three ecological forms with amphidromous, fluvial, and lacustrine lifestyles. Rhinogobius flumineus which is an endemic species in Japan is only fluvial and never descends sea. Dissimilar to other Rhinogobius species, R. flumineus has no planktonic larval stage, adopting a benthic life immediately after hatching (Mizuno 1960). This goby spawns smaller numbers of, but larger eggs than all other species of Rhinogobius species in Japan (Mizuno 1961; Nishijima 1968). During the breeding period (early May to early July), males of R. flumineus make a nest beneath a partially buried stone, following with sequential courtship behaviors directed to a nuptial female (see also Takahashi 2000 & 2006 for general courtship behaviors of this genus). After arriving at the nest, the female deposits a clutch of eggs in a single layer on the nest ceiling. Thereafter, the male attends the egg mass with fanning behavior until hatching (ca. 30 days). The Rhinogobius fishes including R. flumineus have sexual dimorphism; males are larger than females and have longer dorsal fins (ex., Takahashi and Yanagisawa 1999; Takahashi 2000).

 

Collection of fish

              Adult Rhinogobius flumineus were collected using a hand net (1×1mm mesh) along the upper course of the Nigawa River (34°47′N 135°17′E) in Hyogo Prefecture, Japan, from May to July 2021 and 2022. Captured fish were separated by sex and placed into stock tanks (90x45x45cm) supplied with filtered water. The fish were acclimated to laboratory conditions for at least a week before the experiment. The stock tanks and the experimental tanks (see below) were maintained under a 14L:10D photoperiod under fluorescent lights, with a controlled water temperature of approximately 20°C. The conditions in the tanks were similar to those during the breeding period of this species in its natural habitat (D. Takahashi, personal obs.).

 

Female choice and intrasexual mate competition

              A dichotomous mate choice experiment was conducted in the laboratory from May to July 2021 and 2022. The experimental tank (45x30x25cm) was constructed with a 3-cm-thick gravel bottom. In the tank, two male compartments, an experiment female compartment and a rival female compartment were separated with an opaque and two transparent boards (Fig. 3 in the present poster). In this tank, the experiment female could see both males and rival females through the transparent board. The two males could also see the females but could not see each other because of the opaque board between them. To judge which male was chosen by the female, an area at the front of each male compartment was established (i.e., female preference zone). In trials with rival females, two males and three females were placed in each of the male compartments and rival female compartment in the experiment tank. The 3 rival females always contained at least 1 female was ready to spawn as indicated by roundness. The next day, a female that was ready to spawn was introduced into the experiment female compartment. After one hour of acclimatizing the experiment female in the experiment tank, the time spent by the female within the female preference zone in front of each male compartment was measured over a 10-min observation period. In addition, the duration that males courted to females (i.e., male courtship activity) was measured. After measuring these times, the females and males were removed from the tank, male total length (TL), standard length (SL), the first dorsal fin length and body weight (BW). As an indirect index of physiological condition of males, the condition factor (K=BWx10^4/SL^3) was calculated. On the other hand, in trials without rival females, the procedure was adopted by excluding the rival females from trials with rival females.

 

Statistical analysis

              To clarify the female preference for male traits, a generalized linear model (GLM) using a normal error distribution and identity link function were used. In the GLM, to determine which of the candidate models best fit the data, model selection was based on Akaike’s information criterion (AIC), which identifies the model that best explains the dependent variable as that with the lowest AIC value. Corresponding to the method of Takahashi and Kohda (2004), one of the males in each trial was randomly chosen as the focal male. The time that the female stayed within the female preference zone in front of the non-focal male compartment was subtracted from in the time in front of the focal male, and the difference was used as a dependent variable. The positive and negative differences indicated preferred and less preferred males, respectively. In addition, the degree of the differences showed the intensity of female preference. The following 4 independent variables were considered: TL, the proportion of the first dorsal fin length to TL (FDFL), K and male courtship activity (CA). The relative values of these male traits were used in the GLM. The relative values were calculated by first estimating the mean value within a trial pair of males, then subtracting the mean values from the focal male’s values for traits, and finally dividing this deviance by the mean values. All analyses were carried out in EZR ver. 1.55 on R commander (Kanda 2013).

 

References in this Materials and methods

Burnham KP, Anderson DR (2002) Model selection and multimodel inference: a practical information-theoretic approach, 2nd edn. Springer, New York

 

Kanda Y (2013) Investigation of the freely available easy-to-use software 'EZR' for medical statistics. Bone Marr Trans 48: 452–458

 

Mizuno N (1960) Study on a freshwater goby, Rhinogobius similis Gill, with a proposition on the relationships between land-locking and speciation of some freshwater gobies in Japan. Mem Col Sci Univ Kyoto Ser B 27: 97–115

 

Mizuno N (1961) Study on the gobioid fish, "Yoshinobori" Rhinogobius similis Gill–I. Comparison of life histories of three ecological types. Bull Jap Soc Sci Fish 27: 6–11

 

Nishijima S (1968) Two forms of the gobioid fish Rhinogobius brunneus from Okinawa-Jima, Ryukyu Islands. Zool Mag 77: 397–398

 

Takahashi D (2000) Conventional sex role in an amphidromous Rhinogobius goby in which females exhibit nuptial coloration. Ichthyol Res 47:303–306

 

Takahashi D (2006) Courtship behaviour of the freshwater goby Rhinogobius sp. YB. Movie Archives of Animal Behavior. Data No.: momo061012rs01a URL: http://www.momo-p.com/showdetail-e.php?movieid=momo061012rs01a&embed=on Accessed 28 June 2023

 

Takahashi D (2013) Nest site use by two freshwater Rhinogobius gobies inhabiting Lake Biwa in Japan. Ichthyol Res 60: 263-267

 

Takahashi D, Kohda M (2004) Courtship in fast water currents by a male stream goby (Rhinogobius brunneus) communicates the parental quality honestly. Behav Ecol Sociobiol 55: 431-438

 

Takahashi S, Okazaki T (2002) A new lentic form of the ‘‘yoshinobori’’ species complex, Rhinogobius spp. from Lake Biwa, Japan, compared with lake-river migrating Rhinogobius sp. OR. Ichthyol Res 49:333–339

 

Takahashi D, Yanagisawa Y (1999) Breeding ecology of an amphidromous goby of the genus Rhinogobius. Ichthyol Res 46:185–191

 

Yamazaki YY, Nishida M, Suzuki T, Mukai T, Watanabe K (2015) Phylogeny, hybridization, and life history evolution of Rhinogobius gobies in Japan, inferred from multiple nuclear gene sequences. Mol Phylo Evol 90: 20-33

 

References in the present poster presentation

1) Chaine AS, Lyon BE (2008) Adaptive plasticity in female mate choice dampens sexual selection on male ornaments in the lark bunting. Science 319: 459-462

 

2) Jennions MD, Petrie M (1997) Variation in mate choice and mating preferences: a review of causes and consequences. Biol Rev 72: 283-327

 

3) Takahashi D (2019) Female preference for males varies with resource availability for reproduction in the freshwater goby Tridentiger brevispinis. Zool Sci 39: 507-513

 

4) Heubel K (2018) Female mating competition alters female mating preferences in common gobies. Curr Zool 64: 351-361

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5) Takahashi D (2023) Does female mate competition affect female preferences for males in the freshwater goby Rhinogobius biwaensis? The 10th East Asian Federation of Ecological Societies International Congress at Jeju, Korea

 

6) Takahashi D, Kohda M (2004) Courtship in fast water currents by a male stream goby (Rhinogobius brunneus) communicates the parental quality honestly. Behav Ecol Sociobiol 55: 431-438

 

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