It is the ambience,not the menu. Prey availability does not drive habitat selection by the endangered Pyrenean desman

1. The Pyrenean desman (Galemys pyrenaicus) is an endangered stream-dwelling insectivore endemic to the Iberian Peninsula and the north of the Pyrenees. It favours riffles over slow habitats such as runs or pools, yet it is still unclear whether habitat preference is based on prey availability or on other factors, such as mechanical constraints on its hunting habits.
2. Desman diet and prey selection were analysed along the pristine Elama Stream and the slightly modified Leitzaran Stream in the Basque Country, Spain.
3. In each stream the prey consumed were identified by metabarcoding 94 desman faeces, and prey availability characterized from 10 Surber samples taken in each habitat type (riffles, runs and pools). Invertebrates were sorted and identified, the biomass of each taxon was calculated, and their DNA was also extracted, amplified using PCR, and sequenced to build a reference database.
4. Prey availability and diet varied between streams. Desmans positively selected shredders and invertebrates that live on the substrate, and selected against taxa that live in fine sediment, taxa with hard shells or those that are highly mobile. The diet of desmans was more selective in the Elama, the stream with better ecological status. Food availability did not differ among habitats, and therefore does not explain the preference of desmans for riffles; rather, mechanical constraints to deal with buoyancy and physical habitat heterogeneity were hypothesized to be the reason behind the habitat preference.
5. The results suggest that promoting the formation of riffles in streams can improve the situation of some desman populations living in degraded habitats.

     

营养与猪肉品质(综述)

1前言除了遗传,多种营养素、饲养水平、屠宰前处理等影响猪肉品质。本文对近年来有关报道进行综述。2饲粮脂肪成分和水平体脂肪来源于猪内源脂肪和饲粮脂肪两方面,饲粮脂肪可直接沉积为体脂,体脂肪成分在一定程度上反映了饲粮脂肪的成分。因此,确保体脂肪成分在可接受范围内前提下,可通过选择饲粮脂肪来调控体脂肪成分。限制能量摄入减少了内源脂肪的合成,使沉积体脂中源于内源的比例减少、源于饲粮的比例增加。从饲粮中吸收的脂肪酸,特别是多元不饱和脂肪酸,能特异性抑制内源脂肪酸的合成,增加饲粮脂肪成分对体脂成分的影响。饲粮脂肪往往…     

Need for speed: Preference for fast‐flowing water by the endangered semi‐aquatic Pyrenean desman (Galemys pyrenaicus) in two contrasting streams

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