Physiological ecology of frillneck lizards in a seasonal tropical environment

Christian, Keith A.; Griffiths, Anthony D.; Bedford, Gavin S.

doi:10.1007/bf00334406

Cited by 46 publications

(50 citation statements)

References 28 publications

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“…Snakes, especially larger species, may only feed at long intervals of several months, and may undergo long periods of dormancy. However, other large reptile species are also inactive for several months during the year (Pianka 1970(Pianka , 1971(Pianka , 1994Christian et al 1995), and this diminution or lack of food intake for a prolonged period is likely to have an impact on the feeding regime, and hence potential for competition, among infecting nematodes. At such times the metabolism of their nematodes may adapt to conserve energy, as is known to occur in some free-living nematodes (Lant and Storey 2010).…”

Section: Effects Of Host Activitymentioning

confidence: 99%

Physalopterine nematodes in Australian reptiles: interactions and patterns of infection

Jones¹

2014

Aust. J. Zool.

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Abstract. Spirurid nematodes (family Physalopteridae) are widespread as adults or as encysted larvae in many species of Australian reptiles. Fifteen species of physalopterine nematodes (subfamily Physalopterinae) in the genera Kreisiella, Abbreviata and Skrjabinoptera infect more than 40 species of reptile in the five families Agamidae, Varanidae, Gekkonidae, Scincidae and Elapidae. Four species of nematode are host-species specific, six are host-family specific to varanid lizards, and three to agamid lizards. Larger species of reptile support a higher prevalence and abundance of nematodes, and often support multiple infections with more than one species, with the potential for interspecific competition. Geographic distribution of nematodes is partially limited by host distribution, and by climatic factors, mainly precipitation and temperature. There are strong positive and negative associations between several pairs of nematodes. Two species of nematode with the most pronounced muscular development at the anterior end, Abbreviata tumidocapitis and Abbreviata glebopalmae, only occur concurrently, and in low numbers, with species of nematode without these morphological features, suggesting differences in feeding in the hosts' stomachs. A combination of host specificity, geographic distribution and habitat, climatic factors and feeding organ morphology are factors that probably reduce the potential for interspecific competition. There is no evidence that concurrent infections affect either prevalence or abundance of nematodes, or cause discernible pathological changes to their hosts.

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Section: Effects Of Host Activitymentioning

confidence: 99%

Physalopterine nematodes in Australian reptiles: interactions and patterns of infection

Jones¹

2014

Aust. J. Zool.

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“…The dry season is thus a season of limiting resources for many animals (Christian et al , 1999aGriffiths and Christian 1996). Most species of reptiles are much less conspicuous in the dry season, and some enter a period of aestivation (Christian et al 1996a(Christian et al , 1996b(Christian et al , 1996c(Christian et al , 1996dKennett and Christian 1994). Others are active to some extent, but nevertheless expend less energy in the dry season compared to the wet.…”

Section: Introductionmentioning

confidence: 98%

“…Others are active to some extent, but nevertheless expend less energy in the dry season compared to the wet. This reduction in field metabolic rate (FMR) can be accomplished by physiological mechanisms such as metabolic depression (Christian et al 1996b(Christian et al , 1996c(Christian et al , 1999a(Christian et al , 1999b, and behavioural strategies such as thermoregulation at lower body temperatures (T b ) (Christian and Bedford 1995, Christian et al 1996c, 1999b and reduced activity (Christian et al 1996b(Christian et al , 1996c(Christian et al , 1999b. Determining which strategies are employed by a species is critical to our understanding of the annual or life-time energy budgets of the animals.…”

Section: Introductionmentioning

confidence: 99%

Energetics of bluetongue lizards ( Tiliqua scincoides ) in a seasonal tropical environment

2003

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We studied the physiological ecology of bluetongue lizards (Tiliqua scincoides) on the Adelaide River floodplain in tropical Australia to determine the seasonal patterns of energy expenditure and to determine the mechanisms by which seasonal differences were achieved. Field metabolic rates (FMR) were significantly lower in the dry season (37.6 kJ kg(-1) day(-1); n=9) than in the wet (127.3 kJ kg(-1) day(-1); n=7). Water flux was also lower in the dry season (6.8 ml kg(-1) day(-1); n=9) than in the wet (39.4 ml kg(-1) day(-1); n=7). Measurements of body temperatures (T(b)) and movements of free-ranging animals, and standard metabolic rate (SMR) of recently caught animals, allowed a detailed analysis of energy budgets for wet and dry seasons. In the dry, bluetongue lizards expended 90 kJ kg(-1) day(-1) less energy than in the wet season. Unlike some other lizards of the wet-dry tropics, SMR did not differ between seasons. About 5% of the seasonal difference in FMR was due to lower night time T(b) during the dry season, and about 7% was due to lower diurnal T(b). The remaining 88% of the decrease in energy expended in the dry season was due to a substantial decrease in other costs that may include reproduction, growth, digestion and activity. If we assume the animals fed daily and the costs of digestion are taken into account, the estimates are: 14% of the savings result from lower T(b) at night, 20% from lower T(b) in the day, and 66% result from decreased activity. It is therefore apparent that, unlike some agamid and varanid lizards that use a combination of behavioural and physiological mechanisms to conserve energy when food and water are limited, bluetongue lizards primarily use behavioural mechanisms to achieve a dramatic reduction in energy expenditure in the dry season.

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“…The lizard studies that have subdivided the total daily energy expenditure into its components have demonstrated that widely foraging species have higher %ARs than sit-and-wait foragers (Anderson & Karasov 1981;Nagy, Huey & Bennett 1984) and that the proportion of energy used in activity (as well as the daily total) can change seasonally (Alexander & Whitford 1968;Merker & Nagy 1984;Christian & Tracy 1985;Mautz & Nagy 1987;Christian & Weavers 1994;Christian et al 1995;Christian, Griffiths & Bedford 1996a;Christian et al 1996b,c).…”

Section: Introductionmentioning

confidence: 99%

Energetic costs of activity by lizards in the field

Christian¹,

Baudinette

Pamula

1997

Functional Ecology

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Summary 1.The available data related to the activity energetics of lizards in the field were collated with respect to three indices of activity energetics: the ecological cost of transport (ECT) expressed as a percentage of the total energy, the proportion of total energy used in all forms of activity (%AR), and the sustained metabolic scope (SusMS), defined as the ratio of the total energy expenditure to the total resting metabolism. 2. The ECT values of lizards ranged from 3 to 36% with five of 11 species having values >20%. The percentage AR ranged from 23 to 80% for lizards during active seasons, with most species having values > 50%. The SusMS ranged from 1·1 to 5·1. 3. Values of ECT are higher for lizards than for mammals, in part because the costs of maintenance metabolism are higher in mammals. 4. The percentage AR and SusMS values of mammals are higher than those of lizards. 5. It follows from the previous two points that the proportion of the total daily energy that is expended in non-locomotory activities is disproportionately higher in mammals compared with lizards. 6. The energy expended in locomotion is a significant portion of the energy budget of lizards. This is generally true for all seasons in which there is activity.

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Physiological ecology of frillneck lizards in a seasonal tropical environment

Cited by 46 publications

References 28 publications

Physalopterine nematodes in Australian reptiles: interactions and patterns of infection

Physalopterine nematodes in Australian reptiles: interactions and patterns of infection

Energetics of bluetongue lizards ( Tiliqua scincoides ) in a seasonal tropical environment

Energetic costs of activity by lizards in the field

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