Oxygen (δ18O) and carbon (δ13C) isotopic distinction in sequentially sampled tooth enamel of co-localized wild and domesticated caprines: Complications to establishing seasonality and mobility in herbivores

Oxygen isotopes in bioarchaeology: Principles and applications, challenges and opportunities

“…In herbivores, this is largely due to the impact of leaf water consumption, although it should be noted that a similar 'decoupling' of tissue δ 18 O and δ 18 Oew is also common for non-obligate drinking predators, as has been observed in North American felids (Pietsch et al, 2011;Pietsch and Tütken, 2015 counterparts (Kohn et al, 1996;Robinson et al, 2016;Sponheimer and Lee-Thorp, 1999;Stowe and Sealy, 2016). However, in some cases, where both grazing and browsing taxa meet almost all water requirements through leaf water, a reverse scenario with higher δ 18 O values in grazers (relative to browsers) can occur (Bocherens et al, 1996;Makarewicz and Pederzani, 2017). This is brought about by the higher degree of leaf water enrichment in grasses, particularly C4 grasses, compared to dicotyledonous plants (see section 2.3) (Makarewicz and Pederzani, 2017).…”

“…Taxa that are less dependent on water and that mostly meet their water needs through the water in plants, such as caprines or cervids, particularly in arid environments, are often unsuitable for exploration of temperatures and rainfall amount. This is because leaf water isotope signatures can superimpose and therefore obscure relationships with precipitation δ 18 O (Ayliffe and Chivas, 1990;Cormie et al, 1994;Levin et al, 2006;Luz et al, 1990;Makarewicz and Pederzani, 2017). However, this can also be turned to an advantage in studies wishing to investigate aridity.…”

“…However, in some cases, where both grazing and browsing taxa meet almost all water requirements through leaf water, a reverse scenario with higher δ 18 O values in grazers (relative to browsers) can occur (Bocherens et al, 1996;Makarewicz and Pederzani, 2017). This is brought about by the higher degree of leaf water enrichment in grasses, particularly C4 grasses, compared to dicotyledonous plants (see section 2.3) (Makarewicz and Pederzani, 2017). At the same time, dietary changes in herbivorous taxa through time can alter how dependent animals of a certain species are on drinking water and therefore how susceptible they are to leaf water enrichment signals (Faith, 2017).…”

“…Indeed, a multitude of other factors can impact the seasonal amplitude of δ 18 O in herbivore tooth enamel and intra-group variability in addition to movement. Confounding factors that may produce similar isotopic patterns in non-mobile animals and mobile animals are, for instance: the ingestion of water sources with buffering effects, such as lakes, rivers or groundwater (as suggested by Dufour et al, 2014;Henton et al, 2014); intra-group variability in drinking water source (Knockaert et al, 2017); or differences in feeding behaviour in animals ingesting large proportions of leaf water in arid or semi-arid environments (Blumenthal et al, 2017;Levin et al, 2006;Makarewicz and Pederzani, 2017). At the same time, considerable challenges are associated with defining the range of 'local' variation to be expected in a stationary animal, a problem also encountered in provenancing studies and research investigating human residential mobility (see sections 4.4.2 and 4.4.3).…”

“…This approach is particularly relevant for targeting vertical movement patterns and has been used to identify vertical movements of mouflon during the Late Glacial Maximum in the Caucasus region (Tornero et al, 2016) and for caprine herds from the Chalcolithic period in central Anatolia . It should be noted that over-winter foddering may obscure this relationship through the creation of a negative association between δ 13 C and δ 18 O (Chase et al, 2014;Dufour et al, 2014;Makarewicz and Pederzani, 2017), although the co-analysis of wild fauna may go some way to discerning foddering and vertical transhumance in domesticates in certain regions (Makarewicz, 2017 (Britton, 2017). As with other areas of isotope bioarchaeology, however, modern data sets from individuals of known behaviours have proven (and will remain) paramount in the reconstruction of seasonal mobility patterns.…”