Body size and the number of vertebrae in the nine-spined stickleback (Pungitius pungitius)

Abstract

Intraspecific variation in the number of vertebrae is common and taxonomically widespread, although the possible adaptive significance of this variability remains poorly understood. If body size is influenced by the number of vertebrae, then an increased number of vertebrae could facilitate reaching a large body size, and provide a proximate explanation for sex and population differences in mean body size. We tested these predictions using data from 12 populations of nine-spined sticklebacks (Pungitius pungitius), which are known to differ genetically in mean body size, as well as to show a high degree of female-biased sexual size dimorphism. After controlling for the confounding effects of habitat, sex, and population of origin, there was weak and habitat-specific positive association between body size and the number of vertebrae. However, viewed across different populations, there was no correlation between mean body size and the number of vertebrae. Similarly, although females (the larger sex) had, on average, more vertebrae than males, the degree of sexual dimorphism in the number of vertebrae and body size were uncorrelated across populations. Furthermore, there was no relationship between latitude and the mean number of vertebrae, revealing that vertebral numbers in the nine-spined stickleback do not follow Jordan's rule (i.e. increase with increasing latitude). Taken together, the results obtained in the present study suggest that vertebral number only has a very limited influence on intraspecific patterns of body size variation in the nine-spined stickleback.

Age at maturation has sex- and temperature-specific effects on telomere length in a fish

“…One possible explanation for this difference is that costs of maturation are sex-specific. As in many other fish species, delayed maturation in female nine-spined sticklebacks is related to a higher reproductive output (Herczeg et al 2010;Shikano and Merilä 2011). Although we did not analyze reproductive investment in this study, increased reproductive investment is shown to be associated with shorter telomeres in other fish (Gao and Munch 2015) and in birds (Bauch et al 2013;Schultner et al 2013).…”

Proximate cause, anatomical correlates, and obstetrical implication of a supernumerary lumbar vertebra in humans

“…Number of vertebrae, both total and within regional segments (i.e., cervical, thoracic, lumbar, sacral, and caudal) differs among primate and other mammalian species (Erikson, ; Russo & Williams, ; Sargis, ; Schultz, ; Williams, ), among populations within species (Aguirre, Walker, & Gideon, ; Shikano & Merilä, ; Slijepčević, Galis, Arntzen, & Ivanović, ; Tibblin, Berggren, Nordahl, Larsson, & Forsman, ), between sexes within species (Aguirre et al, ; Arntzen, Beukema, Galis, & Ivanović, ; Bardeen, ; Bornstein & Peterson, ; de Beer Kaufman, ; Karapetian, ; Merbs, ; Shikano & Merilä, ; Stewart, ), and among individuals within a population (Allbrook, ; Bornstein & Peterson, ; de Beer Kaufman, ; Merbs, ; Nakajima et al, ). Number of vertebrae is heritable and can evolve by natural selection (Alho, Leinonen, & Merilä, ).…”

Intraspecific variation in fossil vertebrate populations: Fossil killifishes (Actinopterygii: Cyprinodontiformes) from the Oligocene of Central Europe

“…Heritability of vertebral numbers is high, but phenotypic plasticity is well documented (Lindsey, 1988;Yamahira and Nishida, 2009). Differences in sample size, multiyear sampling effects, salinity, and other habitat characteristics may influence the absolute amount of variation observed, as has been reported in other teleosts (e.g., McDowall, 2003;Shikano and Merilä, 2011), including killifishes (Maltagliati et al, 2003). Prolebias rhenanus and Paralebias cephalotes inhabited brackish waters with fluctuating salinity content, whereas Pr.…”

“…Sexual dimorphism may also increase observed variation in abdominal vertebral counts preferentially relative to caudal counts due to selection for increased abdominal volume in females (Lindsey, 1975). Intraspecific variation in vertebral counts is correlated with a multitude of factors in teleosts, including life history (McDowall, 2003), sex (Aguirre et al, 2014;Lindsey, 1975), habitat (Shikano and Merilä, 2011), and temperature/latitude/altitude (Barriga et al, 2013;Baumann et al, 2012;Hice et al, 2012;McDowall, 2003;Yamahira et al, 2006;Yamahira and Nishida, 2009). Heritability of vertebral numbers is high, but phenotypic plasticity is well documented (Lindsey, 1988;Yamahira and Nishida, 2009).…”