This research aimed at assessing the properties of guinea pig manure digestate from low-cost tubular digesters for crops fertilization in rural Andean communities. To this end, field trials were carried out to evaluate the effect of the digestate on two common Andean crops: potato (Solanum tuberosum) and forage (Lolium multiflorum and Trifolium pratense L.). The potato yield (20-25 tha(-1)) increased by 27.5% with digestate, by 15.1% with pre-compost and by 10.3% with the mixture, compared to the control. The forage yield (20-21 tha(-1)) increased by 1.4% with digestate - 50% dose, and by 8.8% with digestate - 100% dose and digestate - 150% dose, compared to the control. The results suggest that the digestate is an appropriate substitute of manure pre-compost for potato fertilization. The results with forage indicate that it can be applied in a range of doses, according to the amount produced by the digester. Currently, manure is either used for cooking or as fertilizer. With low-cost tubular digesters implementation, it could be used to feed the digester, using the digestate for crops fertilization and biogas for cooking; improving household living conditions and protecting the environment. Since soil properties in rural Andean communities differ from experimental layouts, the effect of fertilizers should be re-evaluated in-situ in future research studies.
Aim
To investigate the possibility of range expansion and diversification within the subterranean environment in a genus of troglobiont beetles of the family Leiodidae (Troglocharinus), which have a disjunct distribution between the Pyrenees and the Catalonian coast.
Location
North‐eastern Iberian Peninsula.
Methods
We sequenced 4 kb of five mitochondrial and two nuclear genes of 50 specimens of 12 of the 18 species of Troglocharinus, plus several outgroups. We reconstructed a phylogeny using Bayesian inference and maximum likelihood, estimated divergence times using Bayesian probabilities and an a priori evolutionary rate, compared the diversification of the main clades within the genus, and reconstructed their ancestral distribution using maximum likelihood.
Results
We found strong support for the monophyly of Troglocharinus and the clades in each of the geographical areas, which diverged in the early Pliocene. The coastal clade was further divided into geographically well‐defined lineages, separated by Quaternary deposits. The origin of the coastal clade was a single colonization in the early Pliocene from the central Pyrenees. The diversification of the Pyrenean clade followed a constant rate, while the diversification rate of the coastal clade significantly decreased through the Plio‐Pleistocene transition.
Main conclusions
Troglocharinus expanded its range from its ancestral area in the central Pyrenees to the coast of Catalonia and subsequently diversified, probably within the subterranean environment. Our favoured scenario is a stepping‐stone migration, with possibly short‐distance dispersals through the surface, along the eastern margin of the north‐eastern Ebro basin. The range expansion took place in a narrow temporal window with favourable conditions between the early Pliocene and the onset of the Mediterranean climate by the mid‐Pliocene. Surface dispersal was probably severely limited afterwards, as shown by the fragmentation of the coastal lineage.
One of the main challenges in ecology, biogeography and evolution is to understand and predict how species may respond to environmental changes. Here we focus on the deep subterranean environment, a system that minimizes most of the typical uncertainties of studies on epigean (surface) environments. Caves are relatively homogeneous habitats with nearly constant environmental conditions and simplified biological communities, allowing to control for biotic interactions. Thus, this particular system could be considered a natural habitat whose environmental conditions are similar to what can be reproduced in a laboratory, being an ideal model system for ecological, biogeographical and evolutionary studies. Subterranean species may potentially be used to assess the capability to persist in situ in a global change scenario, as they cannot accommodate to drastic changing conditions by behavioural plasticity, microhabitat use or by migrating to distant, more suitable areas, something frequent in epigean environments. In order to provide accurate predictions of the response of the subterranean biodiversity to climate change, we encourage evolutionary biologist, biogeographers and conservation biologist to work in this interesting ecosystem.
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