Evol Ecol Res 20: 213-230 (2019)     Full PDF if your library subscribes.

Diversity of gill raker number and diets among stickleback populations in novel habitats created by the 2011 Tōhoku earthquake and tsunami

Takuya Hosoki^1,2, Seiichi Mori³, Shotaro Nishida³, Manabu Kume⁴, Tetsuya Sumi⁵ and Jun Kitano^1,2

¹Ecological Genetics Laboratory, National Institute of Genetics, Mishima, Shizuoka, Japan, ²Department of Genetics, SOKENDAI, Mishima, Shizuoka, Japan,  ³Gifu-keizai University, Ogaki, Gifu, Japan,  ⁴Field Science Education and Research Center, Kyoto University, Kyoto, Japan and  ⁵Daido University, Nagoya, Aichi, Japan

Correspondence: J. Kitano, Ecological Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan. email: jkitano@nig.ac.jp

ABSTRACT

Background: Catastrophic disasters often create novel habitats and offer an opportunity to investigate how rapidly phenotypic diversification occurs in nature. On 11 March 2011, a large earthquake and subsequent tsunami struck the downtown area of Otsuchi Town, Iwate Prefecture, Japan. This catastrophic event created new spring water-fed ponds that sticklebacks (genus Gasterosteus) quickly colonized. In 2014, there were 48 newly formed stickleback habitats.

Questions: Does trophic morphology and ecology vary among stickleback populations in newly created ponds? Is the morphological variation associated with any ecological or environmental factors in the newly formed habitats?

Methods: We sampled sticklebacks from four native and 17 novel habitats in 2014. We counted the number of gill rakers (an important trophic trait in fish) and analysed their stomach contents. We measured salinity, water temperature, pH, dissolved oxygen, and the density of benthos in the habitats and conducted principal component analysis on these environmental factors. Then, we tested whether any environmental factors or environmental principal components are associated with variation in gill raker number.

Results: The number of gill rakers varied significantly among the newly formed populations. Fish with fewer gill rakers had a higher proportion of benthos in their stomach, suggesting that gill raker number may contribute to the performance of benthic feeding. Furthermore, we found that sticklebacks in habitats with higher benthos density had fewer gill rakers.

Keywords: contemporary evolution, diet, empty niche, hybridization, rapid diversification, trophic ecology.

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