Physiological Responses of the Mexican Woodrat (Neotoma mexicana) to Condensed Tannins

Voltura, Mary Beth; Wunder, Bruce A.

doi:10.2307/2426598

Cited by 6 publications

(6 citation statements)

References 18 publications

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“…Digestive enzymes and bacteria are adapted to a consumer's normal diet. Consumption of even small quantities of novel secondary compounds can have a variety of negative consequences that influence growth, time to reproductive maturity, and survival (Freeland and Janzen 1974, Lindroth and Batzli 1984, Voltura and Wunder 1994, Mangione et al 2000). However, some herbivores may be capable of overcoming the threat of novel toxins by sampling small amounts until the appropriate detoxification mechanisms have been induced (Freeland and Janzen 1974).…”

Section: Discussionmentioning

confidence: 99%

Evidence for local specialization in a generalist mammalian herbivore, Neotoma fuscipes

McEachern

Eagles‐Smith

Efferson

et al. 2006

Oikos

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Herbivores with very plastic dietary requirements, or so‐called generalist species, can include individuals that develop specialized feeding habits through their experience with local chemically‐defended plants. Local specialization has important implications for understanding a variety of ecological and evolutionary dynamics. However, the extent to which individuals within a generalist species specialize on local plants and the consequences of such specialization remain poorly understood, especially in non‐insect herbivores. To better understand this phenomenon, we determined the diet and food preferences of a generalist mammalian herbivore, the dusky‐footed woodrat (Neotoma fuscipes), in two adjacent but distinct plant communities. Based on a combination of cafeteria trials and stable isotope analyses (δ13C and δ15N), our results indicate that woodrats display preferences for local plants and tend to avoid novel chemically‐defended plants. Moreover, both methodologies support the conclusion that individual woodrats are dietary specialists restricting their diets to only a few (2‐3) of the available plant species. In juniper woodland, woodrats prefer western juniper (Juniperus occidentalis), while less than one km away in mixed‐coniferous forest, woodrats prefer incense cedar (Calocedrus decurrens). Both plants contain high levels of plant secondary compounds that require detoxification mechanisms within consumers. Therefore, preferences are likely indicative of underlying physiological adaptations that could promote further behavioral, physiological and ultimately genetic differences between woodrats in different habitats. This study provides additional evidence for local specialization and urges caution when using the term generalist to characterize feeding behaviors at the individual level.

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Section: Discussionmentioning

confidence: 99%

Evidence for local specialization in a generalist mammalian herbivore, Neotoma fuscipes

McEachern

Eagles‐Smith

Efferson

et al. 2006

Oikos

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“…Experimental diets containing high concentrations of CT depressed dry matter intake and weight gain in herbivorous mammals (Dietz et al 1994;Voltura and Wunder 1994;Lee et al 1995). A reduction in the utilization of dietary protein For personal use only.…”

Section: Function and Location Of Condensed Tannins In Plantsmentioning

confidence: 99%

A review of the effects of forage condensed tannins on ruminal fermentation and bloat in grazing cattle

McMahon¹,

McAllister²,

Berg³

et al. 2000

Can. J. Plant Sci.

239

178

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[469][470][471][472][473][474][475][476][477][478][479][480][481][482][483][484][485]. Condensed tannins (CT) are polyphenolic secondary plant products that are widespread in the plant kingdom. By definition, CT bind to protein and are regarded as "antinutritional" compounds which reduce protein digestibility. Variations in CT chemistry alter protein binding capacities among polymers from different plant species and developmental stages. Condensed tannins interact with proteins in feed, saliva and microbial cells, with microbial exoenzymes, and with endogenous proteins or other feed components, which alters digestive processes as compared with diets free of CT. Tannin levels exceeding 40 to 50 g kg -1 DM in forages may reduce protein and DM digestibility of the forages by ruminants. At low to moderate levels, CT increase the quantity of dietary protein, especially essential amino acids, flowing to the small intestine. Unlike alfalfa, legumes that contain CT do not cause bloat. Dietary CT may provide a means to beneficially manipulate protein digestion and/or prevent pasture bloat in ruminants. Research efforts are also currently being directed to genetically modify alfalfa to de-repress its CT biosynthetic pathway, or to move genes encoding steps of this pathway into alfalfa from other legumes. The effects of CT in forage legumes on digestion in ruminants and the potential use of tannin-rich forages for preventing bloat in grazing systems are discussed. Les tanins condensés (TC) sont des substances secondaires polyphénoliques répandues dans le règne végétal. Par essence fixés aux protéines, ils sont considérés comme substances antinutritionnelles qui réduisent la digestibilité des protéines. Leur constitution chimique, et par conséquent leur aptitude à se fixer aux protéines, fluctue selon la nature et le stade de croissance des espèces végétales. Les tanins condensés interagissent avec les protéines dans les aliments du bétail, dans la salive et dans les cellules microbiennes; avec les exoenzymes microbiens et avec les protéines endogènes ou avec d'autres composants des aliments du bétail, modifiant ainsi le processus de la digestion par rapport aux aliments sans TC. Des teneurs en tanins de plus de 40 à 50 g kg -1 m.s. dans les fourrages peuvent abaisser la digestibilité des protéines et de la matière sèche chez les ruminants. À des niveaux faibles à moyens, les TC accroissent le flux de protéines alimentaires, en particulier celui des acides aminés essentiels, vers l'intestin grêle. À la différence de la luzerne, les légumineuses qui contiennent des TC ne provoquent pas le météorisme. L'apport de TC dans l'alimentation des animaux peut être un moyen de manipuler positivement la digestion des protéines ou de prévenir le météorisme chez les ruminants au pâturage. Les recherches s'orientent également ves la modification génétique de la luzerne pour contrer l'inhibition de la biosynthèse des TC ou pour introduire dans l'espèce, à partir d'autres légumineuses, des gènes codant pour certaines étapes de cette voie....

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“…There were no insects that attack herbaceous plants, no gall-forming insects, no leafminers, no bark beetles, no sawflies, no hemimetabolous insects, no mammals, etc. Coleogyne tannin lacked biological activity against any of the insect herbivores assayed here, but it is highly active against goats, hares, and wood rats (Provenza et al 1990, Clausen et al 1990, Voltura and Wunder 1994.…”

Section: Differences Among Herbivores In Their Sensitivity To Tanninmentioning

confidence: 99%

“…Some research supports the hypothesis that tannins act as an antiherbivore defense by binding with dietary protein and digestive enzymes to limit assimilation in herbivores (e.g., Mitaru et al 1984, Robbins et al 1987a, b, 1991, Cooper et al 1988. Other studies suggest that toxicity, rather than digestive inhibition, is the Manuscript received 28 March 1996;revised 17 October 1996;accepted 1 November 1996;final version received 5 December 1996. mode of action (Lindroth and Batzli 1984, Steinly and Berenbaum 1985, Blytt et al 1988, Thomas et al 1988, Karowe 1989, Mole et al 1990, Voltura and Wunder 1994. Finally, there are frequent reports that tannins have no detectable effect on herbivores (Bernays et al 1980, Klock and Chan 1982, Manuwoto and Scriber 1986, Martin et al 1987, Smith et al 1992, McArthur and Sanson 1993a, or that they even function as nutritive substrates supporting growth (Bernays and Woodhead 1982).…”

Section: Introductionmentioning

confidence: 99%

Diversity of Structure and Antiherbivore Activity in Condensed Tannins

Ayres¹,

Clausen²,

MacLean³

et al. 1997

Ecology

101

143

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We characterized the structure of condensed tannins from 16 woody plant species (seven genera, six families) and determined their effects on six herbivorous insect species (four genera, two families). There were major differences in tannin structure, even between congeneric plant species. Condensed tannins differed markedly in their antiherbivore activity, averaged over these herbivores, and the herbivores differed in their sensitivity, averaged over these tannins. Furthermore, the same tannin can have different effects on different herbivores, presumably because of interactions between tannin structure and gut physiology. Results challenge the view that tannins provide an evolutionarily stable plant defense because of their uniform chemical properties. Condensed tannin can sometimes impact herbivore fitness through effects on survival and growth, but the largest effects in 45 insect-tannin combinations were less than that of many other plant metabolites at lower doses. Even at high doses, condensed tannins frequently had no strong antiherbivore activity, even against insects with no evolutionary history of encountering the tannin (Ͻ10% reduction in growth rate in 24 of 45 experiments). Most condensed tannins apparently do not have broad-spectrum antiherbivore activity. We doubt that selective pressures from folivorous insects can be the main explanation for the diversion of so much carbon, in so many plant species, into the synthesis of condensed tannins.

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Physiological Responses of the Mexican Woodrat (Neotoma mexicana) to Condensed Tannins

Cited by 6 publications

References 18 publications

Evidence for local specialization in a generalist mammalian herbivore, Neotoma fuscipes

Evidence for local specialization in a generalist mammalian herbivore, Neotoma fuscipes

A review of the effects of forage condensed tannins on ruminal fermentation and bloat in grazing cattle

Diversity of Structure and Antiherbivore Activity in Condensed Tannins

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