Feeding biology of two functionally different foregut‐fermenting mammals, the marsupial red kangaroo and the ruminant sheep: how physiological ecology can inform land management

Munn, Adam J.; Dawson, Terence J.; McLeod, Steven R.

doi:10.1111/j.1469-7998.2010.00740.x

Cited by 15 publications

(20 citation statements)

References 48 publications

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“…In contrast to macropods, artiodactyl mammals (even-toed ungulates in the eutherian lineage; deer, sheep, camels and kin) have limited manual dexterity, and quadrupedal gaits in which the loads are spread more evenly among fore- and hindlimbs during both slow and fast gaits, reflected in similarity of forelimb and hindlimb bones' cross-sectional properties [ 11 ]. Artiodactyls and macropods spend a large proportion of their time grazing or resting as they are foregut fermenter herbivores [ 12 ] and may be considered ecological equivalents [ 13 ]. Extinct giant macropods probably could not hop due to tissue strength being exceeded by scaling of muscle and tendon stress [ 9 ], yet even the largest artiodactyls retain high-speed gaits.…”

Section: Introductionmentioning

confidence: 99%

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

et al. 2018

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Bone adaptation is modulated by the timing, direction, rate and magnitude of mechanical loads. To investigate whether frequent slow, or infrequent fast, gaits could dominate bone adaptation to load, we compared scaling of the limb bones from two mammalian herbivore clades that use radically different high-speed gaits, bipedal hopping (suborder Macropodiformes; kangaroos and kin) and quadrupedal galloping (order Artiodactyla; goats, deer and kin). Forelimb and hindlimb bones were collected from 20 artiodactyl and 15 macropod species (body mass M 1.05–1536 kg) and scanned in computed tomography or X-ray microtomography. Second moment of area (Imax) and bone length (l) were measured. Scaling relations (y = axb) were calculated for l versus M for each bone and for Imax versus M and Imax versus l for every 5% of length. Imax versus M scaling relationships were broadly similar between clades despite the macropod forelimb being nearly unloaded, and the hindlimb highly loaded, during bipedal hopping. Imax versus l and l versus M scaling were related to locomotor and behavioural specializations. Low-intensity loads may be sufficient to maintain bone mass across a wide range of species. Occasional high-intensity gaits might not break through the load sensitivity saturation engendered by frequent low-intensity gaits.

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Section: Introductionmentioning

confidence: 99%

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

et al. 2018

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“…Hopping is likely not possible at body mass over ~160 kg, at which the distal tendons' safety factor (ratio of actual to ultimate stress) drops below 1, meaning that extinct 'giant kangaroos' would have used slower gaits [7][8][9][10].In contrast to macropods, artiodactyl mammals (even-toed ungulates in the eutherian lineage; deer, sheep, camels and kin) have limited manual dexterity, and quadrupedal gaits in which the loads are spread evenly among fore-and hindlimbs during both slow and fast gaits, reflected in similarity of forelimb and hindlimb bones' cross-sectional properties [11]. Artiodactyls and macropods spend a large proportion of their time grazing or resting as they are foregut fermenter herbivores [12] and may be considered ecological equivalents [13]. Extinct giant macropods could not hop due to tissue strength being exceeded by scaling of muscle and tendon stress [9], yet even the largest artiodactyls retain high-speed gaits.…”

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confidence: 99%

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

Doube

Felder

Chua

et al. 2018

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Bone adaptation is modulated by the timing, direction, rate, and magnitude of mechanical loads. To investigate whether frequent slow, or infrequent fast, gaits could dominate bone adaptation to load, we compared scaling of the limb bones from two mammalian herbivore clades that use radically different high-speed gaits, bipedal hopping and quadrupedal galloping. Forelimb and hindlimb bones were collected from 20 artiodactyl and 15 diprotodont species (body mass M 1.05 -1536 kg) and scanned in clinical computed tomography or X-ray microtomography. Second moment of area (I max ) and bone length (l) were measured. Scaling relations (y = ax b ) were calculated for l vs M for each bone and for I max vs M and I max vs l for every 5% of length. I max vs M scaling relationships were broadly similar between clades despite the diprotodont forelimb being nearly unloaded, and the hindlimb highly loaded, during bipedal hopping. I max vs l and l vs M scaling were related to locomotor and behavioural specialisations. Low-intensity loads may be sufficient to maintain bone mass across a wide range of species. Occasional high-intensity gaits might not break through the load sensitivity saturation engendered by frequent low-intensity gaits. IntroductionDuring daily rest and activity, bones experience a range of mechanical loading conditions that relate to each behaviour's physical intensity. Bones respond anabolically, that is, by increasing bone tissue formation and decreasing bone resorption, when they experience a small number of novel high strain and high strain rate events with a rest period between bouts of loading [1,2]. Repetitive loading has a saturation or habituation effect, in which tissue is no longer responsive to mechanical loads after a few tens of cycles [2]. Large numbers of loading cycles without sufficient rest are associated with fatigue or 'stress' fractures, typically seen in new military recruits [3] and racing animals such as greyhounds [4] and horses [5,6]. The distributions of occasional maximal loads and habitual moderate loads vary within the skeleton and depend on locomotor activity, which should appear as a morphological signal in clades that adopt very different characteristic gaits [7].

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“…Indeed, more recent studies have revealed that M. fuliginosus forage mostly on grasses (with monocot grasses comprising at least 44% and up to 81% of forestomach contents) 14,40 while M. rufus can subsist on fewer grasses but more chenopods (c. Fifteen% and c. 63% respectively). 16 While differences in grazing behavior between species may vary with pasture abundance, 26 increased foraging time by M. fuliginosus may compound issues associated with being restricted to the shade, although they rested for an equivalent amount of time.…”

Section: Discussionmentioning

confidence: 99%

“… 42 Second, restriction to the shade for consecutive hours throughout the day could impact gut refill time and thus digestion 43 ; gut filling allows kangaroos to focus their feeding at thermally-favorable times. 16 Third, by foraging during the day, the kangaroos would be able to seek shelter at night to avoid heat losses under clear night sky. 2,44 Furthermore, both kangaroo species might forage during the day to reduce risks associated with night-time predation, though vigilance behavior of M. giganteus actually decreases after dark.…”

Section: Discussionmentioning

confidence: 99%

A continent-wide analysis of the shade requirements of red and western grey kangaroos

et al. 2016

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Foraging time may be constrained by a suite of phenomena including weather, which can restrict a species' activity and energy intake. This is recognized as pivotal for many species whose distributions are known to correlate with climate, including kangaroos, although such impacts are rarely quantified. We explore how differences in shade seeking, a thermoregulatory behavior, of 2 closely-related kangaroo species, Macropus rufus (red kangaroos) and M. fuliginosus (western grey kangaroos), might reflect differences in their distributions across Australia. We observed foraging and shade-seeking behavior in the field and, together with local weather observations, calculated threshold radiant temperatures (based on solar and infrared radiant heat loads) over which the kangaroos retreated to shade. We apply these calculated tolerance thresholds to hourly microclimatic estimates derived from daily-gridded weather data to predict activity constraints across the Australian continent over a 10-year period. M. fuliginosus spent more time than M. rufus in the shade (7.6 ± 0.7 h versus 6.4 ± 0.9 h) and more time foraging (11.8 ± 0.5 h vs. 10.0 ± 0.6 h), although total time resting was equivalent (∼8.2 h). M. rufus tolerated 19°C higher radiant temperatures than M. fuliginosus (89°C versus 70°C radiant temperature). Across Australia, we predicted M. fuliginosus to be more restricted to shade than M. rufus, with higher absolute shade requirements farther north. These results corroborate previous findings that M. rufus is more adept at dealing with heat than M. fuliginosus and indicate that M. rufus is less dependent on shade on a continental scale.

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Feeding biology of two functionally different foregut‐fermenting mammals, the marsupial red kangaroo and the ruminant sheep: how physiological ecology can inform land management

Cited by 15 publications

References 48 publications

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

Limb bone scaling in hopping macropods and quadrupedal artiodactyls

A continent-wide analysis of the shade requirements of red and western grey kangaroos

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