Observations of breeding behaviour and possible infanticide in a wild population of Tasmanian echidnas (Tachyglossus aculeatus setosus)

Harris, Rachel L.; Nicol, Stewart C.

doi:10.1071/am13011

Cited by 10 publications

(2 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The highest leptin levels were found in both sexes during hibernation and in females during the mating period. As female echidnas return to hibernation after mating, even when pregnant, unless they are further disturbed by males (Harris and Nicol, 2014 ; Morrow et al, 2015 ), the high leptin in mating females is most probably also related to hibernation. The lowest leptin levels were recorded from males during the post-reproductive period, when they forage maximally and show their greatest increase in mass (Nicol and Morrow, 2012 ).…”

Section: Leptin and Energeticsmentioning

confidence: 99%

Energy Homeostasis in Monotremes

Nicol

2017

Front. Neurosci.

Self Cite

View full text Add to dashboard Cite

In 1803, the French anatomist Étienne Geoffroy Saint-Hilaire decided that the newly described echidna and platypus should be placed in a separate order, the monotremes, intermediate between reptiles and mammals. The first physiological observations showed monotremes had low body temperatures and metabolic rates, and the consensus was that they were at a stage of physiological development intermediate between “higher mammals” and “lower vertebrates.” Subsequent studies demonstrated that platypuses and echidnas are capable of close thermoregulation in the cold although less so under hot conditions. Because the short-beaked echidna Tachyglossus aculeatus, may show very large daily variations in body temperature, as well as seasonal hibernation, it has been suggested that it may provide a useful model of protoendotherm physiology. Such analysis is complicated by the very significant differences in thermal relations between echidnas from different climates. In all areas female echidnas regulate Tb within 1°C during egg incubation. The lactation period is considered to be the most energetically expensive time for most female mammals but lactating echidnas showed no measurable difference in field metabolic rate from non-lactating females, while the lactation period is more than 200 days for Kangaroo Island echidnas but only 150 days in Tasmania. In areas with mild winters echidnas show reduced activity and shallow torpor in autumn and early winter, but in areas with cold winters echidnas enter true hibernation with Tb falling as low as 4.5°C. Monotremes do not possess brown adipose tissue and maximum rates of rewarming from hibernation in echidnas were only half those of marmots of the same mass. Although echidnas show very large seasonal variations in fat stores associated with hibernation there is no relationship between plasma leptin and adiposity. Leptin levels are lowest during post-reproductive fattening, supporting suggestions that in evolutionary terms the anorectic effects of leptin preceded the adiposity signal. BMR of platypuses is twice that of echidnas although maximum metabolism is similar. High levels of thyroid hormones in platypuses may be driving metabolism limited by low body temperature. Monotremes show a mosaic of plesiomorphic and derived features but can still inform our understanding of the evolution of endothermy.

show abstract

Section: Leptin and Energeticsmentioning

confidence: 99%

Energy Homeostasis in Monotremes

Nicol

2017

Front. Neurosci.

Self Cite

View full text Add to dashboard Cite

show abstract

“…While the short (21 day) pregnancy (Morrow et al, ) does not seem to be disrupted by further mating, male harassment of females with an egg or burrow young may lead to loss of the young, and the female re‐entering oestrous (Harris & Nicol, ), and as shown in Figure , late matings involved females that had lost an egg or young. While observations in Tasmania (Harris & Nicol, ) and Queensland (Beard & Grigg, ) show that some females will re‐enter oestrous and mate again after losing their young, this is rarely successful. A mating in mid‐October would mean the young would be weaned in mid‐April, and in Tasmania, neither mother nor young would be likely to gain sufficient condition to survive the winter.…”

Section: Discussionmentioning

confidence: 99%

Energetics meets sexual conflict: The phenology of hibernation in Tasmanian echidnas

2019

Self Cite

View full text Add to dashboard Cite

Echidnas are egg‐laying mammals found across Australia, and in Tasmania they hibernate, resulting in a most unusual mating system: males enter hibernation in late summer–early autumn and arouse in late autumn–early winter to mate, although females are still hibernating. Groups of males compete for matings and both males and females mate with multiple partners. Females that mate early return to hibernation even when pregnant, and males continue to mate with pregnant females. We asked to what extent can the bizarre combination of behavioural and physiological features that characterize reproduction of Tasmanian echidnas be attributed to their phylogeny, and how much is a consequence of their ecology? To understand the interaction between energetics and the echidna mating system in determining the timing of echidna hibernation, we analysed data from an 18‐year study of a wild population of Tasmanian echidnas (Tachyglossus aculeatus setosus) Males in best condition arouse earliest and seek out suitable females, and females that mate early in the mating season re‐enter hibernation while pregnant. Competition between males drives early mating and while mating with males in the best condition could be advantageous for females and their young, egg‐laying in winter is potentially disadvantageous, and post‐mating hibernation by females is a means of delaying hatching of young until environmental conditions are more favourable. This post‐mating hibernation by females is usually disrupted by males which mate with them although they are already pregnant. Comparisons with other echidna populations suggest that a decreased activity period due to hibernation has not increased male–male competition. Similar competition between groups of males for access to females is seen in chlamyphorid armadillos, which occupy a similar ecological niche to echidnas. A free Plain Language Summary can be found within the Supporting Information of this article.

show abstract