Altitudinal Effects on Innate Immune Response of a Subterranean Rodent.

Solak HM, Yanchukov A, Colak F, et al. Altitudinal Effects on Innate Immune Response of a Subterranean Rodent. Zoological science. 2020;37(1):31-41.Immune defense is costly to maintain and deploy, and the optimal investment into immune defense depends on risk of infection. Altitude is a natural environmental factor that is predicted to affect parasite abundance, with lower parasite abundance predicted at higher altitudes due to stronger environmental stressors, which reduce parasite transmission. Using high and low altitude populations of the Turkish blind mole-rat (TBMR) Nannospalax xanthodon, we tested for effects of altitude on constitutive innate immune defense. Field studies were performed with 32 wild animals in 2017 and 2018 from two low- and one high-altitude localities in the Central Taurus Mountains, at respective altitudes of 1010 m, 1115 m, and 2900 m above sea level. We first compared innate standing immune defense as measured by the bacteria-killing ability of blood serum. We then measured corticosterone stress hormone levels, as stressful conditions may affect immune response. Finally, we compared prevalence and intensity of gastrointestinal parasites of field-captured TBMR. We found that the bacteria-killing ability of serum is greater in the mole-rat samples from high altitude. There was no significant difference in stress (corticosterone) levels between altitude categories. Coccidian prevalence and abundance were significantly higher in 2017 than 2018 samples, but there was no significant difference in prevalence, abundance, or intensity between altitudes, or between sexes. Small sample sizes may have reduced power to detect true differences; nevertheless, this study provides support that greater standing innate immunity in high altitude animals may reflect greater investment into constitutive defense

Do Seismic Signals Diverge at the Level of Cytotypes in Turkish Blind Mole Rats?

Subterranean animals are limited in mobility and have reduced sensory ability due to living underground, and therefore are presented with a challenge to communicate. One solution is to use seismic signalling, by head drumming, to convey species-specific information. The lesser blind mole rats (Nannospalax sp.) are obligate subterranean rodents known for their remarkable chromosomal variation. In the present study, we investigated whether the structure of seismic signalling is different between the two species found in Turkey, Nannospalax leucodon and the N. xanthodon and whether it is associated with ecological, sex, temporal and chromosomal peculiarities. A cytotype of N. leucodon (2n=56) and three cytotypes of N. xanthodon, (2n=38, 52 and 60) were used in the study. We observed no seismic signalling in N. leucodon. In N. xanthodon, the cytotype 2n=60 had faster rate of signalling in comparison to two other cytotypes (2n=38 and 2n=52), and the cytotypes also differed significantly in the structural components of their signals. There was no difference in signal pattern between different fundamental number variations within cytotypes. We observed temporal variation in seismic signals, but did not found any difference in signalling between the sexes, suggesting the signals are not used for mate recognition. In addition, the signalling structure was not associated with the climate and the soil types of the habitat of origin. We suggest that seismic communication by drumming may be used to recognize conspecifics within the same cytotype or species