Microfungal oasis in an oligotrophic desert: diversity patterns and community structure in three freshwater systems of Cuatro Cienegas, Mexico
Por:
Velez, Patricia, Gasca-Pineda, Jaime, Rosique-Gil, Edmundo, Eguiarte, Luis E., Espinosa-Asuar, Laura, Souza, Valeria
Publicada:
2 jun 2016
Resumen:
The Cuatro Cienegas Basin (CCB) comprises several oligotrophic aquatic
ecosystems limited by phosphorus. These aquatic systems are dominated by
a high prokaryotic diversity, shaped by the stress of low nutrient
supplies and interspecific competition. Although fungi constitute a
diverse and important component of microbial diversity, the microfungal
diversity in the CCB remains to be unveiled. With the aim to explore
microfungal diversity and ecological patterns in this area, we present
the first investigation analyzing cultivable taxa from sediment and
water, as well as lignocellulolytic taxa obtained from incubated
submerged plant debris, and wood panels in three contrasting freshwater
systems in the CCB: Churince, Becerra and Pozas Rojas. We chose a
culture-based approach to analyze sediment and water samples in order to
obtain fungal cultures, providing opportunities for a posteriori
studies, and the possibility of ex situ preservation of the diversity.
We evaluated sequence data from the nuclear ribosomal internal
transcribed spacer including the 5.8 rDNA region for 126 isolates,
revealing 37 OTUs. These OTUs were phylogenetically affiliated to
several genera in the fungal phyla: Zygomycota, Basidiomycota, and
Ascomycota. We recorded two OTUs with saline affinity, agreeing with
previous findings on the prokaryotic communities with ancestral marine
resemblances. All the studied systems showed moderate diversity levels,
however discrepancies among the diversity indexes were observed, due to
the occurrence of abundant taxa in the samples. Our results indicated
that lignocellulolytic microfungal communities are dominated by
transient fungal taxa, as resident species were not recorded perhaps as
a result of the long-term strong competition with the highly adapted
prokaryotic community. Moreover, the obtained microfungal taxa occurred
mostly on the resident plant debris, rather than submerged wood panels,
perhaps as a result of the high adaptation to specific environmental
conditions. In conclusion, the CCB possess a moderate taxonomical
diversity compared to other arid environments, probably as a result of
high selective pressures. Nonetheless, due to high spatial and temporal
heterogeneity, the functional fungal diversity was considerable as
predicted by the intermediate disturbance hypothesis. Decisively, the
assessment of microfungal diversity freshwater systems is relevant,
since this ecological group of microorganisms represents an important
indicator of trophic complexity and biotic interactions among microbial
communities, having important implications for understanding eukaryotic
survival at the oligotrophic limit for life.
Filiaciones:
Velez, Patricia:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
Gasca-Pineda, Jaime:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
Rosique-Gil, Edmundo:
Univ Juarez Autonoma Tabasco, Div Acad Ciencias Biol, Villahermosa, Tabasco, Mexico
Eguiarte, Luis E.:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
Espinosa-Asuar, Laura:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
Souza, Valeria:
Univ Nacl Autonoma Mexico, Inst Ecol, Dept Ecol Evolut, Mexico City 04510, DF, Mexico
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