Can antioxidant responses be induced by habitat fragmentation process?

Abstract

Animal populations are increasingly forced to live in small residual natural or seminatural areas due to habitat loss and fragmentation. Here, the viability of populations is often compromised by intrinsic threat factors typical of small and isolated populations, such as inbreeding depression, genetic drift and environmental and demographic stochasticity. Under these circumstances, organisms may have low fitness due to inadequate physiological responses needed to face environmental challenges. However, few studies have investigated the relationship between habitat fragmentation and stress defences. In this study, we aimed to test whether an increase in the level of individual inbreeding produced an increase in the antioxidant system response. To this purpose, we genotyped 151 individuals of fire salamander Salamandra salamandra (Amphibia: Urodela) within five sampling populations, located in forest landscapes with different degree of fragmentation in northern Italy. For 113 individuals we also measured the glutathione-S-transferase (GST) and catalase (CAT) enzyme activity. Results showed a significant increase in individual GST activity for increasing levels of inbreeding, whereas no relationship was found for CAT. We also measured acetylcholinesterase to test the possible confounding effects of pesticides that might have occurred in fragmented landscapes with forests interspersed with agricultural areas. However, no difference in this enzyme activity was found among sampling populations. We argue that high levels of GST activity may be symptomatic of oxidative stress derived from inbreeding. An increased frequency of homozygous deleterious alleles due to inbreeding may cause homeostatic alterations and trigger the expression of GST for protection against hydrogen peroxide reactive oxygen species. We suggest using GST as a biomarker for environmental stressors with great caution and not to underestimate that the sources of stress deriving from habitat fragmentation could lead to an unbalance in the oxidative status, possibly increasing population susceptibility to infectious diseases and, potentially, spillover events and zoonoses.

Biomonitoring of Alterations in Fish That Inhabit Anthropic Aquatic Environments in a Basin from Semi-Arid Regions

“…It is important to note that TBARS showed a high correlation with metals, indicating that it could be a useful biomarker for metal exposition. In this sense, aquatic invertebrates exhibit induction of CAT and TBARS as a defense against heavy metals and pesticides, to mediate biotransformation of xenobiotics and detoxification from hydrogen peroxide [ 47 ]. Added to this, the alterations of the cholinergic system (estimated in this study by the ChE activity) are signs of risk due to contamination [ 47 ].…”

“…In this sense, aquatic invertebrates exhibit induction of CAT and TBARS as a defense against heavy metals and pesticides, to mediate biotransformation of xenobiotics and detoxification from hydrogen peroxide [ 47 ]. Added to this, the alterations of the cholinergic system (estimated in this study by the ChE activity) are signs of risk due to contamination [ 47 ]. In total accordance with these reports, we consider the possibility that the negative effects of environmental contamination may be mediated by a disruption of the oxidative balance, decreasing adaptability and contributing to reduced fitness of aquatic organisms [ 11 , 47 ].…”

“…Added to this, the alterations of the cholinergic system (estimated in this study by the ChE activity) are signs of risk due to contamination [ 47 ]. In total accordance with these reports, we consider the possibility that the negative effects of environmental contamination may be mediated by a disruption of the oxidative balance, decreasing adaptability and contributing to reduced fitness of aquatic organisms [ 11 , 47 ]. Furthermore, these findings provide a more complete picture of the oxidative status of individuals threatened by habitat fragmentation [ 47 ].…”

“…In total accordance with these reports, we consider the possibility that the negative effects of environmental contamination may be mediated by a disruption of the oxidative balance, decreasing adaptability and contributing to reduced fitness of aquatic organisms [ 11 , 47 ]. Furthermore, these findings provide a more complete picture of the oxidative status of individuals threatened by habitat fragmentation [ 47 ]. However, as some authors mention, further studies should include the measurement of more antioxidant parameters as well as other aspects of oxidative stress (e.g., oxidative DNA damage).…”

Seasonal variation in spider abundance in Muthupet mangroves, South East coast of Tamilnadu, India

“…Spiders are a critical factor in ecological biodiversity since they function as predators and food for other organisms in the ecosystem. Because of their small body structure, short reproduction period and acute sensitivity to temperature and moisture changes, they are considered signi cant biological monitors of ecosystem changes and habitat adaptation (Jose et al, 2018;Strungaru et al, 2021;Multisanti et al, 2022;Bani et al, 2022). The mangrove forest's large leaf canopy provides a constant and shady habitat, resulting in higher humidity in favouring the formation of faunal colonization.…”