Rasgos fisiológicos y biológicos que definen el nicho ecológico en corixidae (hemiptera)respuestas al cambio climático e invasiones biológicas

Resumo

Abstract The main goal of this thesis is to address key physiological and biological traits characterizing the ecological niche of related Corixidae species: native Sigara species and the exotic Trichocorixa verticalis verticalis, the only aquatic hemipteran recognized as an invader in Europe. The study of the ecological niche of these species can explain their distributions, co-occurrence patterns, and responses to environmental changes. The obtained results can provide insights on the impact of climate change and biological invasions at population/species and community levels. Chapter 1 compares the saline and ionic composition realized niches of three Sigara species along a salinity gradient with their fundamental niche experimentally obtained. Results showed a strong concordance between both, the realized and the fundamental niches. Young life-stages of the species showed less salinity tolerance than adults. Physiological limitations were not found at laboratory in relation to fresh and less saline waters in the saline species S. selecta, so other factors, probably involving biotic interactions, may play an important role in the distribution of this species. Chapter 2 determines intraspecific variation in physiological and biological responses to environmental change between core and marginal populations of the saline species Sigara selecta within its geographical range. The obtained results are discussed in the frame of climate change. The marginal population showed higher phenotypic plasticity in metabolic and fecundity traits than the core population. The higher plasticity of the marginal population may facilitate northward expansion with future climatic warming. By contrast, the core population, more resistant, may be able to buffer current environmental variability with minor changes in metabolism and fecundity. However, it could be more prone to extinction if temperature and salinity changes exceed physiological tolerance limits in the future. Chapter 3 explores which physiological and biological traits underpin the invasion success of the invader corixid Trichocorixa verticalis verticalis against some competitive Sigara native species at the Iberian Peninsula. The establishment and spread success of T. v. verticalis could be principally due to its high egg production, high resistance to salinity, heat and harsh environmental conditions, and its better flight dispersal ability. Finally, Chapter 4 characterizes the habitat specialization and functional niches, co-occurrence patterns and assembly rules of the invader T. v. verticalis and three native coexisting corixids. The main aim was to evaluate its impacts on native species from the Iberian Peninsula and North Morocco invasion areas. Our results showed that the invader species modifies the distribution and co-occurrence patterns of the native Sigara species along the salinity gradient. Thus, in non-invaded areas habitat filtering drives habitat segregation of the species by its differential salinity tolerance, whereas in the invaded area niche differentiation shapes the community as a mechanism favoring coexistence among the invasive and native saline species through resource partitioning.