The 10th EAFES International Congress at Jeju, Korea

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Does female mate competition affect female preferences for males in the freshwater goby Rhinogobius biwaensis?

 

TAKAHASHI Daisuke (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 biwaensis which is an endemic species in Lake Biwa, Japan is only lacustrine and never ascends affluent streams (Takahashi and Okazaki 2002). During the breeding period (early May to late August), males of R. biwaensis make a nest beneath a partially buried stone (Takahashi 2013), 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. 4 days). The Rhinogobius fishes including R. biwaensis 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 biwaensis were collected using a hand net (1x1mm mesh) along the Minamihama shoreline (35°23′N 136°13′E) of Lake Biwa, Japan from May to August 2019. The water depth of the collection ranged from 30 to 200 cm. The area of shoreline sampled consisted of sand with many cobbles that are potential available nest sites for R. biwaensis. 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 24°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 August 2019. 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 PA2-001). 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. After measuring the time that the female remained within the female preference zone in front of each male compartment, the females and males were removed from the tank, male total length (TL), standard length (SL), the first dorsal fin length, the second 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.

 

Relationship between male traits and physiological condition

              In order to clear relationships between male traits and physiological condition, males used in the above mate choice experiment were randomly selected and measured TL, the first and second dorsal fin length and body weight (BW). Thereafter, males were dissected out and recorded gonad weight (GW) and liver weight (LW). As more direct indices of physiological condition than the condition factor, the gonadosomatic index (GWx100/BW) and the hepatosomatic index (LWx100/BW) were calculated.



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 with correction for a small sample size (AICc; Burnham and Anderson, 2002), which identifies the model that best explains the dependent variable as that with the lowest AICc value. Significance of independent variables in the model was assessed by log-likelihood χ^2. Corresponding to the method of Takahashi and Kohda (2004), one of the males in each trial was randomly chosen as the focal male. The proportion of the time that the female stayed within the female preference zone in front of the focal male compartment to the observation period (that is, 600s) was regarded as female preference and used as a dependent variable. The proportion was arc-sine transformed for the GLM. The following four independent variables were considered: TL, the first dorsal fin length adjusted by TL (FDFL), the second dorsal fin length adjusted by TL (SDFL) and K. The relative values of these four 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. In order to clear relationship between male traits and physiological condition, I performed simple regression analysis. I regarded GSI or HSI as dependent variable and TL, FDFL and SDFL as independent variables. All analyses were carried out in JMP 10.0.2 (SAS Institute Inc., 2012).

 

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

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

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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

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

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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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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

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

 

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

 

6) Suk HY, Choe JC (2008) Dynamic female preference for multiple signals in Rhinogobius brunneus. Behav Ecol Sociobiol 62: 945-951