Yüksekliğin Anadolu Kör Faresi Nannospalax xanthodon'un doğal bağışıklık sistemine etkisi ve lokal popülasyonların genetik yapılarının tespiti

Immune defense is costly to maintain and deploy, and the optimal investment into immune defense should depend on the risk of infection. Altitude is a natural environmental factor predicted to affect parasite abundance, with lower parasite abundance expected at higher altitudes because of stronger environmental stressors that reduce parasite transmission. Therefore, investment in immune response predicted to depend on the strength of selection imposed by parasites and the availability of resources. The possible differences in immune response may also be caused by neutral divergence between the populations, or they can be affected by gene flow between geographically close populations. Using high, middle and low altitude populations of the Anatolian blind mole rat (ABMR), Nannospalax xanthodon, we tested for effects of altitude on constitutive innate immune defense, and the amount of neutral genetic divergence between these populations. Field studies were performed with 48 wild animals in 2017, 2018 and 2019 from two high, one middle and three low altitude populations in the Central Taurus Mountains, at respective altitudes of 1010 m, 1115 m, 1350 m, 1700 m, 2580 m and 2900 m above sea level. We first compared standing innate immune defense among these populations as measured by bacteria killing ability of blood plasma. We then measured corticosterone stress hormone levels because stressful conditions may affect immune response. Furthermore, we compared prevalence and intensity of gastrointestinal parasites of field-captured ABMR. Finally, we tested the neutral genetic divergence between altitude populations by eight microsatellite markers. We found that bacteria killing ability of plasma is greater in the mole-rat samples from high altitude populations. There was no significant difference in stress (corticosterone) levels between altitude categories. Parasite prevalence was significantly higher in 2017 samples but there was no significant difference in abundance or intensity between altitudes nor between sexes. The amount of neutral genetic differences between altitudes were likely too small to be detected with the given markers. Small sample sizes may have reduced our power to detect true differences, nevertheless, this study provides preliminary support that greater standing innate immunity in high altitude animals may reflect greater investment into constitutive defense. These functional differences could be caused by strong natural selection for adaptation to the mountain environment.