Daily and Seasonal Rhythms in Selected Body Temperatures in the Australian Lizard<i>Tiliqua rugosa</i>(Scincidae): Field and Laboratory Observations

Firth, Bruce T.; Belan, Ingrid

doi:10.1086/515919

Cited by 69 publications

(50 citation statements)

References 4 publications

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“…Although it was possible for the tegus to achieve higher maximum T b through behavioural thermoregulation, that they did not suggest an endogenous seasonal rhythm, similar to that seen in the sleepy lizard, T. rugosa (Firth and Belan 1998;Ellis et al 2008). From April into May, there was a further significant nighttime drop in f H and f R indicating a further suppression in metabolism, but this was associated with a significant fall in T b .…”

Section: The Pattern Of Metabolic Rate Reduction Leading Into Dormancymentioning

confidence: 89%

Daily and annual cycles in thermoregulatory behaviour and cardio-respiratory physiology of black and white tegu lizards

et al. 2015

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This study was designed to determine the manner in which metabolism is suppressed during dormancy in black and white tegu lizards (Tupinambis merianae). To this end, heart rate (fH), respiration rate (fR), and deep body temperature (Tb) were continuously monitored in outdoor enclosures by radio-telemetry for nine months. There was a continuous decline in nighttime breathing and heart rate, at constant Tb, throughout the late summer and fall suggestive of an active metabolic suppression that developed progressively at night preceding the entrance into dormancy. During the day, however, the tegus still emerged to bask. In May, when the tegus made a behavioural commitment to dormancy, Tb (day and night) fell to match burrow temperature, accompanied by a further reduction in fH and fR. Tegus, under the conditions of this study, did arouse periodically during dormancy. There was a complex interplay between changes in fH and Tb associated with the direct effects of temperature and the indirect effects of thermoregulation, activity, and changes in metabolism. This interplay gave rise to a daily hysteresis in the fH/Tb relationship reflective of the physiological changes associated with warming and cooling as preferred Tb alternated between daytime and nighttime levels. The shape of the hysteresis curve varied with season along with changes in metabolic state and daytime and nighttime body temperature preferences.

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Section: The Pattern Of Metabolic Rate Reduction Leading Into Dormancymentioning

confidence: 89%

Daily and annual cycles in thermoregulatory behaviour and cardio-respiratory physiology of black and white tegu lizards

et al. 2015

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“…Adult sleepy lizards are long-lived (Ͼ20 years) (23) and mainly herbivorous (24,25). They are predominantly active from spring to early summer (late August to December) (26,27). They form monogamous partnerships for 6 to 8 weeks before mating in early November, and these partnerships re-form over successive years (28)(29)(30).…”

Section: Methodsmentioning

confidence: 99%

Spatial Variation and Survival of Salmonella enterica Subspecies in a Population of Australian Sleepy Lizards (Tiliqua rugosa)

Parsons

Bull

Gordon

2015

Appl Environ Microbiol

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bThe life cycles of many enteric bacterial species require a transition between two very distinct environments. Their primary habitat is the gastrointestinal tract of the host, while their secondary habitat, during transmission from one host to another, consists of environments external to the host, such as soil, water, and sediments. Consequently, both host and environmental factors shape the genetic structure of enteric bacterial populations. This study examined the distribution of four Salmonella enterica subspecies in a population of sleepy lizards, Tiliqua rugosa, in a semiarid region of South Australia. The lizards living within the 1,920-m by 720-m study site were radio tracked, and their enteric bacteria were sampled at regular intervals throughout their active seasons in the years 2001, 2002, and 2006. Four of the six subspecies of S. enterica were present in this population and were nonrandomly distributed among the lizards. In particular, S. enterica subsp. diarizonae was restricted to lizards living in the most shaded parts of the study site with an overstorey of Casuarina trees. Experiments undertaken to investigate the survival of S. enterica cells under seminatural conditions revealed that cell survival decreased with increased exposure to elevated temperatures and UV light. Among the three S. enterica subspecies tested, S. enterica subsp. diarizonae consistently had an average expected life span that was shorter than that observed for the other two subspecies. There was no indication in the data that there was any competitive dominance hierarchy among the S. enterica subspecies within individual hosts. Thus, the nonrandom distribution of S. enterica subspecies in this population of lizards appears to be driven by their different survival characteristics in the external environment.

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“…The study area experiences rapid changes in vegetation structure as the abundance and distribution of annual plants respond to periods of rainfall or drought. The sleepy lizard is most active during the austral spring and early summer of each year (mid-September to mid-December; Bull, 1987;Firth & Belan, 1998), the time when we conducted our study. In early spring 2012, we established four 500 Â 500 m sites within the study area, separated by 0.5e1.0 km.…”

Section: Study Site and Experimental Designmentioning

confidence: 99%

Environment modulates population social structure: experimental evidence from replicated social networks of wild lizards

et al. 2016

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Social structure is a fundamental component of a population that drives ecological and evolutionary processes ranging from parasite transmission to sexual selection. Nevertheless, we have much to learn about factors that explain variation in social structure. We used advances in biologging and social network analysis to experimentally test how the local habitat, and specifically habitat complexity, modulates social structure at different levels in wild populations. Sleepy lizards, Tiliqua rugosa, establish nonrandom social networks that are characterized by avoidance of some neighbours and frequent interactions with one opposite-sex individual. Using synchronous GPS locations of all adult lizards, we constructed social networks based on spatial proximity of individuals. We increased habitat structural complexity in two study populations by adding 100 short fences across the landscape. We then compared the resulting movement behaviour and social structure between these populations and two unmanipulated populations. Social connectivity (network density) and social stability, measured at weekly intervals, were greater in populations with increased habitat structural complexity. The level of agonistic interaction (quantified as scale damage) was also higher, indicating a fitness cost of greater social connectivity. However, some network parameters were unaffected by increased complexity, including disassortative mixing by sex, and at the individual level, social differentiation among associates (coefficient of variation of edge weights) and maximal interaction frequencies (maximal edge weight). This suggests divergent effects of changed ecological conditions on individual association behaviour compared to the resulting social structure of the population. Our results contrast with those from studies of more gregarious species, in which higher structural complexity in the environment relaxed the social connectivity. This shows that the response to altered ecological conditions can differ fundamentally between species or between populations, and we suggest that it depends on their tendency for gregarious behaviour.

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Daily and Seasonal Rhythms in Selected Body Temperatures in the Australian LizardTiliqua rugosa(Scincidae): Field and Laboratory Observations

Cited by 69 publications

References 4 publications

Daily and annual cycles in thermoregulatory behaviour and cardio-respiratory physiology of black and white tegu lizards

Daily and annual cycles in thermoregulatory behaviour and cardio-respiratory physiology of black and white tegu lizards

Spatial Variation and Survival of Salmonella enterica Subspecies in a Population of Australian Sleepy Lizards (Tiliqua rugosa)

Environment modulates population social structure: experimental evidence from replicated social networks of wild lizards

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