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Climatic warming and the future of bison as grazers.

Craine JM, Towne EG, Miller M, Fierer N - Sci Rep (2015)

Bottom Line: Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality.Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots.Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass.

View Article: PubMed Central - PubMed

Affiliation: Jonah Ventures, Manhattan KS 66502, USA.

ABSTRACT
Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality. Yet accurate predictions of the effects of climatic warming on herbivores are limited by a poor understanding of how herbivore diet varies along climate gradients. We utilized DNA metabarcoding to reconstruct seasonal variation in the diet of North American bison (Bison bison) in two grasslands that differ in mean annual temperature by 6 °C. Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots. Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass. Instead, bison diet in the warmer grassland had a greater proportion of N2-fixing eudicots, regularly comprising >60% of their protein intake in spring and fall. Although bison have been considered strict grazers, as climatic warming reduces grass protein concentrations, bison may have to attempt to compensate by grazing less and browsing more. Promotion of high-protein, palatable eudicots or increasing the protein concentrations of grasses will be critical to minimizing warming-imposed nutritional stress for bison and perhaps other large mammalian herbivores.

No MeSH data available.


Related in: MedlinePlus

Seasonal pattern of relative read abundances (RRAs) in bison fecals within each of four functional groups.(a,e) C3 graminoids, (b,f) C4 grasses, (c,g) non-N2-fixing eudicots, (d,h) N2-fixing eudicots for Kansas (a–d) and South Dakota (e–h) bison. All OTUs were aggregated to shared common genera. RRAs are only shown for the top 50 most abundant OTUs, which comprised an average of 90% of all reads. Data shown for 2011, 2013, 2014 for Kansas and 2014 for South Dakota.
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f2: Seasonal pattern of relative read abundances (RRAs) in bison fecals within each of four functional groups.(a,e) C3 graminoids, (b,f) C4 grasses, (c,g) non-N2-fixing eudicots, (d,h) N2-fixing eudicots for Kansas (a–d) and South Dakota (e–h) bison. All OTUs were aggregated to shared common genera. RRAs are only shown for the top 50 most abundant OTUs, which comprised an average of 90% of all reads. Data shown for 2011, 2013, 2014 for Kansas and 2014 for South Dakota.

Mentions: DNA metabarcoding revealed that Kansas bison consumed a diverse diet of graminoids and eudicots. Eudicots represented a majority of the trnL reads recovered. For the Kansas bison across the entire three years, 39% of the sequences were from graminoids: 8 ± 1% (s.e.) were graminoids with the C3 photosynthetic pathway, 31 ± 2% were grasses with the C4 photosynthetic pathway. In contrast, 61% of the sequences were from eudicots: 18 ± 2% were from non-N2-fixing forbs and 43 ± 3% were from N2-fixing species. The temporal patterns of the plant functional groups in Kansas bison revealed that C3 graminoid consumption was highest during the winter (~20% from Nov 1 – Apr 1 vs. 3% for the rest of the year; Fig. 1). Consumption of C3 graminoids in the winter was mostly Carex (sedge) species, which often remains green throughout the winter (Fig. 2). C4 grass relative read abundance (RRA) averaged 30–40% for most of the year except in early April when it declined to ~10%.


Climatic warming and the future of bison as grazers.

Craine JM, Towne EG, Miller M, Fierer N - Sci Rep (2015)

Seasonal pattern of relative read abundances (RRAs) in bison fecals within each of four functional groups.(a,e) C3 graminoids, (b,f) C4 grasses, (c,g) non-N2-fixing eudicots, (d,h) N2-fixing eudicots for Kansas (a–d) and South Dakota (e–h) bison. All OTUs were aggregated to shared common genera. RRAs are only shown for the top 50 most abundant OTUs, which comprised an average of 90% of all reads. Data shown for 2011, 2013, 2014 for Kansas and 2014 for South Dakota.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645125&req=5

f2: Seasonal pattern of relative read abundances (RRAs) in bison fecals within each of four functional groups.(a,e) C3 graminoids, (b,f) C4 grasses, (c,g) non-N2-fixing eudicots, (d,h) N2-fixing eudicots for Kansas (a–d) and South Dakota (e–h) bison. All OTUs were aggregated to shared common genera. RRAs are only shown for the top 50 most abundant OTUs, which comprised an average of 90% of all reads. Data shown for 2011, 2013, 2014 for Kansas and 2014 for South Dakota.
Mentions: DNA metabarcoding revealed that Kansas bison consumed a diverse diet of graminoids and eudicots. Eudicots represented a majority of the trnL reads recovered. For the Kansas bison across the entire three years, 39% of the sequences were from graminoids: 8 ± 1% (s.e.) were graminoids with the C3 photosynthetic pathway, 31 ± 2% were grasses with the C4 photosynthetic pathway. In contrast, 61% of the sequences were from eudicots: 18 ± 2% were from non-N2-fixing forbs and 43 ± 3% were from N2-fixing species. The temporal patterns of the plant functional groups in Kansas bison revealed that C3 graminoid consumption was highest during the winter (~20% from Nov 1 – Apr 1 vs. 3% for the rest of the year; Fig. 1). Consumption of C3 graminoids in the winter was mostly Carex (sedge) species, which often remains green throughout the winter (Fig. 2). C4 grass relative read abundance (RRA) averaged 30–40% for most of the year except in early April when it declined to ~10%.

Bottom Line: Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality.Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots.Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass.

View Article: PubMed Central - PubMed

Affiliation: Jonah Ventures, Manhattan KS 66502, USA.

ABSTRACT
Climatic warming is likely to exacerbate nutritional stress and reduce weight gain in large mammalian herbivores by reducing plant nutritional quality. Yet accurate predictions of the effects of climatic warming on herbivores are limited by a poor understanding of how herbivore diet varies along climate gradients. We utilized DNA metabarcoding to reconstruct seasonal variation in the diet of North American bison (Bison bison) in two grasslands that differ in mean annual temperature by 6 °C. Here, we show that associated with greater nutritional stress in warmer climates, bison consistently consumed fewer graminoids and more shrubs and forbs, i.e. eudicots. Bison in the warmer grassland consumed a lower proportion of C3 grass, but not a greater proportion of C4 grass. Instead, bison diet in the warmer grassland had a greater proportion of N2-fixing eudicots, regularly comprising >60% of their protein intake in spring and fall. Although bison have been considered strict grazers, as climatic warming reduces grass protein concentrations, bison may have to attempt to compensate by grazing less and browsing more. Promotion of high-protein, palatable eudicots or increasing the protein concentrations of grasses will be critical to minimizing warming-imposed nutritional stress for bison and perhaps other large mammalian herbivores.

No MeSH data available.


Related in: MedlinePlus