Seasonal Changes in Spermatogenesis (Including Germ Cell Degeneration) and Plasma Testosterone Concentration in the Grey-headed Fruit Bat, Pteropus poliocephalus

McGuckin, MichaeI A; Blackshaw, A. W.

doi:10.1071/bi9870211

Cited by 19 publications

(22 citation statements)

References 25 publications

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“…4). This pattern corresponds to that found earlier in captivity (Hamilton and Barclay 1998;McGuckin and Blackshaw 1991b;O'Brien 1993) and in the wild (McGuckin and Blackshaw 1987;Nelson 1965b). In several mammal species, testis size is dependent on body condition (Schulte-Hostedde et al 2005a), because spermatogenesis can be energetically expensive (e.g.…”

Section: Discussionsupporting

confidence: 65%

Fit females and fat polygynous males: seasonal body mass changes in the grey-headed flying fox

Welbergen

2010

Oecologia

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When females and males differ in their timing of maximum reproductive effort, this can result in sex-specific seasonal cycles in body mass. Such cycles are undoubtedly under strong selection, particularly in bats, where they affect flying ability. Flying foxes (Old World fruit bats, Pteropus spp.) are the largest mammals that can sustain powered flight and therefore face critical trade-offs in managing body reserves for reproduction, yet little is known about body mass dynamics in this group. I investigated body mass changes in relation to reproductive behaviour in a large colony of grey-headed flying foxes (Pteropus poliocephalus). In this polygynous mammal, females were predicted to maximise reproductive effort during lactation and males during the breeding season. As predicted, female body condition declined during the nursing period, but did not vary in relation to sexual activity. By contrast, males accumulated body reserves prior to the breeding season, but subsequently lost over 20% of their body mass on territory defence and courtship, and lost foraging opportunities as they also defended their day roost territories at night. Males in better condition had larger testes, particularly during territory establishment, prior to maximum sexual activity. Thus, the seasonality of female mass reflected the high metabolic load that lactation imposes on mothers. However, male mass followed a pattern akin to the "fatted male phenomenon", which is commonly observed in large polygynous mammals with seasonal reproduction, but not in bats. This shows the importance of body reserves for reproduction in flying foxes, despite their severe constraints on body mass.

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Section: Discussionsupporting

confidence: 65%

Fit females and fat polygynous males: seasonal body mass changes in the grey-headed flying fox

Welbergen

2010

Oecologia

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“…The seasonal pattern of plasma testosterone concentrations was also similar to that seen in wild animals (McGuckin & Blackshaw, 1987), although the current data provide a complete seasonal record. When testicular size was increasing, plasma concentrations were slightly higher than during the time of testicular regression, but were significantly lower than during the mating period (just after the greatest testicular size was attained).…”

Section: P Poliocephalusmentioning

confidence: 69%

“…Leydig cells first appear active, histologically, well before the peak in testosterone. Although ultrastructural analysis of Leydig cells was not under¬ taken, regressive morphological changes (reduced nuclear diameter and cytoplasmic volume) have been demonstrated in Leydig cells of wild bats during testicular regression (McGuckin & Blackshaw, 1987). Peak testosterone concentrations during mid-April, although high, were less than the highest found during March in the wild.…”

Section: P Poliocephalusmentioning

confidence: 99%

“…During the mating period, males copulate frequently with the females in their harem within the camps during the day; some mating also occurs at feeding sites during the nightly forage. Testicular size alters seasonally in this species, being greatest during February and March and least from June to September (McGuckin & Blackshaw, 1987;Nelson, 1963). The breeding seasons of P. alecto and P. conspicillatus appear, on limited evidence, to have a similar timing to that of P. poliocephalus.…”

Section: Introductionmentioning

confidence: 99%

“…The greatest body weight attained increased over each year of the study although the greatest testicular size was similar from year to year. AODFAJAODFAJAODFAJ SNJMMJSNJMMJ SNJMM 1987198419851986 Fig (McGuckin & Blackshaw, 1987;Nelson, 1963) because of incomplete monthly collections in both these studies. Testicular recrudescence in grey-headed flying foxes clearly began several months before the summer solstice (21 December), although growth was greatest after the solstice.…”

Section: P Poliocephalusmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal changes in testicular size, plasma testosterone concentration and body weight in captive flying foxes (Pteropus poliocephalus and P. scapulatus)

McGuckin

Blackshaw²

1991

Reproduction

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Comparative morphology of the pituitary gland in Australian flying foxes (megachiroptera: GenusPteropus)

O'Brien

1996

Anat. Rec.

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Background Investigations of reproductive endocrinology of flying foxes (genus Pteropus) have been hampered by inadequate information on the normal morphology of the megachiropteran pituitary. Methods The novel technique of graphical three‐dimensional (3‐D) reconstruction, supported by more traditional anatomical techniques, have now been used to examine the shapes of, the interrelations between, the lobes of the pituitary of the little red flying fox, Pteropus scapulatus. Statistical analysis of data from three species tested whether there were changes in pituitary size with annual cycles in function, particularly with key stages of reproduction. Results In the three species of Australian flying foxes examined, the hypophyseal cleft is closed; the pars intermedia extends over the rostral, ventral, and lateral surfaces of the neural lobe. The pars distalis is broad rostrally and extends over two‐thirds of the lateral and ventral pars intermedia. The hypophyseal recess is broad at the median eminence, then narrows and extends through the infundibulum to, but not into, the neural lobe. In adult animals the pituitary weight was 10.0 ± 0.3 mg (mean ± s.e.) in P. scapulatus, 14.7 ± 0.5 mg in Pteropus poliocephalus (greyheaded flying foxes), and 18.7 ± 1.5 mg in Pteropus alecto (black flying foxes). Pituitary weight was not significantly affected by reproductive stage. Conclusions Thus histologically, the adenohypophysis and neurohypophysis are similar to those of other mammals. Comparative differences in pituitary size reflected differences in species body size rather than cyclical reproduction. © 1996 Wiley‐Liss, Inc.

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Seasonal Changes in Spermatogenesis (Including Germ Cell Degeneration) and Plasma Testosterone Concentration in the Grey-headed Fruit Bat, Pteropus poliocephalus

Cited by 19 publications

References 25 publications

Fit females and fat polygynous males: seasonal body mass changes in the grey-headed flying fox

Fit females and fat polygynous males: seasonal body mass changes in the grey-headed flying fox

Seasonal changes in testicular size, plasma testosterone concentration and body weight in captive flying foxes (Pteropus poliocephalus and P. scapulatus)

Comparative morphology of the pituitary gland in Australian flying foxes (megachiroptera: GenusPteropus)

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