scholarly journals Experimental manipulation of fertility reveals potential lactation costs in a free-ranging marsupial

2011 ◽  
Vol 7 (6) ◽  
pp. 859-862 ◽  
Author(s):  
Jemma K. Cripps ◽  
Michelle E. Wilson ◽  
Mark A. Elgar ◽  
Graeme Coulson
Keyword(s):  
Experimental Tests ◽  
Fertility Control ◽  
Cost Of Reproduction ◽  
Experimental Manipulation ◽  
Control Agent ◽  
Gastrointestinal Parasites ◽  
Costs Of Reproduction ◽  
Potential Cost ◽  
Forage Intake ◽  
Free Ranging

Lactation is the most energetically expensive component of reproduction in mammals. Theory predicts that reproducing females will adjust their behaviour to compensate for increased nutritional demands. However, experimental tests are required, since comparisons of the behaviour of naturally reproducing and non-reproducing females cannot distinguish between true costs of reproduction, individual differences or seasonal variation. We experimentally manipulated reproduction in free-ranging, eastern grey kangaroos ( Macropus giganteus ), using a fertility control agent. Our novel field experiment revealed that females altered their behaviour in direct response to the energetic demands of reproduction: reproducing females increased bite rates, and thus food intake, when the energetic demands of lactation were highest. Reproducing females did not reduce the time spent on vigilance for predators, but increased their forage intake on faecal-contaminated pasture, thereby increasing the risk of infection by gastrointestinal parasites—a largely unrecognized potential cost of reproduction.

scholarly journals Costs of reproduction and carry-over effects in breeding albatrosses

2016 ◽  
Vol 29 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Glenn T. Crossin ◽  
richard A. Phillips ◽  
Christine R. Lattin ◽  
L. Michael Romero ◽  
Xavier Bordeleau ◽  
...  
Keyword(s):  
Cost Of Reproduction ◽  
Breeding Strategy ◽  
Costs Of Reproduction ◽  
Potential Cost ◽  
Future Studies ◽  
Thalassarche Melanophris ◽  
Carry Over ◽  
Apparent Susceptibility ◽  
Feather Corticosterone ◽  
Carry Over Effect

AbstractWe investigated the physiology of two closely related albatross species relative to their breeding strategy: black-browed albatrosses (Thalassarche melanophris) breed annually, while grey-headed albatrosses (T. chrysostoma) breed biennially. From observations of breeding fate and blood samples collected at the end of breeding in one season and feather corticosterone levels (fCort) sampled at the beginning of the next breeding season, we found that in both species some post-breeding physiological parameters differed according to breeding outcome (successful, failed, deferred). Correlations between post-breeding physiology and fCort, and links to future breeding decisions, were examined. In black-browed albatrosses, post-breeding physiology and fCort were not significantly correlated, but fCort independently predicted breeding decision the next year, which we interpret as a possible migratory carry-over effect. In grey-headed albatrosses, post-breeding triglyceride levels were negatively correlated with fCort, but only in females, which we interpret as a potential cost of reproduction. However, this potential cost did not carry-over to future breeding in the grey-headed albatrosses. None of the variables predicted future breeding decisions. We suggest that biennial breeding in the grey-headed albatrosses may have evolved as a strategy to buffer against the apparent susceptibility of females to negative physiological costs of reproduction. Future studies are needed to confirm this.

Tales of lizard tails: effects of tail autotomy on subsequent survival and growth of free-ranging hatchling Uta stansburiana

1997 ◽  
Vol 75 (4) ◽  
pp. 542-548 ◽  
Author(s):  
P. H. Niewiarowski ◽  
J. D. Congdon ◽  
A. E. Dunham ◽  
L. J. Vitt ◽  
D. W. Tinkle
Keyword(s):  
Natural Populations ◽  
Reproductive Investment ◽  
Experimental Manipulation ◽  
Costs And Benefits ◽  
Growth And Survival ◽  
Large Sample ◽  
Uta Stansburiana ◽  
Tail Autotomy ◽  
Trade Offs ◽  
Free Ranging

Potential costs and benefits of tail autotomy in lizards have been inferred almost exclusively from experimental study in semi-natural enclosures and from indirect comparative evidence from natural populations. We present complementary evidence of the costs of tail autotomy to the lizard Uta stansburiana from detailed demographic study of a natural population. On initial capture, we broke the tails of a large sample of free-ranging hatchlings (560) and left the tails of another large sample (455) intact, and then followed subsequent hatchling growth and survival over a 3-year period. Surprisingly, in 1 out of the 3 years of study, survival of female hatchlings with broken tails exceeded that of female hatchlings with intact tails. Furthermore, no effects of tail loss on survivorship were detected for male hatchlings. However, in 2 years when recaptures were very frequent (1961, 1962), growth rates of hatchlings with broken tails were significantly slower than those of their counterparts with intact tails. We discuss our results in the broader context of estimating the relative costs and benefits of tail autotomy in natural populations, and suggest that long-term demographic studies will provide the best opportunity to assess realized fitness costs and benefits with minimum bias. We also describe how experimentally induced tail autotomy can be used as a technique to complement experimental manipulation of reproductive investment in the study of life-history trade-offs.

Stability of cabergoline in fox baits in laboratory and field conditions

2007 ◽  
Vol 34 (3) ◽  
pp. 239 ◽  
Author(s):  
Stuart McLean ◽  
Susan Brandon ◽  
Roger Kirkwood
Keyword(s):  
High Performance ◽  
Acetic Acid Solution ◽  
Hydrolysis Product ◽  
Fertility Control ◽  
Field Trials ◽  
Control Agent ◽  
Field Conditions ◽  
Dry Conditions ◽  
The Stability ◽  
Fox Control

Cabergoline is a potent inhibitor of prolactin release and a potential fertility control agent for foxes. To understand how cabergoline could behave in baits deployed for fox control, we conducted laboratory and field trials to investigate the stability of cabergoline when (1) in solution, (2) injected into a bait (deep-fried liver and Foxoff®) and (3) exposed to a range of environmental conditions, including burial. Cabergoline, dissolved in a 1% acetic acid solution, and its carboxylic acid hydrolysis product can be assayed using high-performance liquid chromatography. When stored at 4°C and at room temperature, cabergoline in solution was stable for up to 36 days. When stored under cool (≤15°C), dry conditions, cabergoline (800 µg) in commercial Foxoff® and deep-fried ox-liver baits was stable for 28 and 7 days, respectively; stability was reduced by increases in temperature (tested up to 40°C) and humidity. Recovery of cabergoline from buried baits exposed to a range of field conditions decreased rapidly in the first week, but after 56 days remained detectable at levels of 6–22% of the injected amounts. This study has important implications for baiting campaigns that use cabergoline for fox control.

scholarly journals A pilot study of common health problems in smallholder pigs in Angónia and Boane districts, Mozambique

2011 ◽  
Vol 82 (3) ◽  
Author(s):  
C. Matos ◽  
C. Sitoe ◽  
S. Afonso ◽  
J. Banze ◽  
J. Baptista ◽  
...  
Keyword(s):  
Health Risks ◽  
Taenia Solium ◽  
African Swine Fever ◽  
Health Problems ◽  
Gastrointestinal Parasites ◽  
Pilot Survey ◽  
Porcine Cysticercosis ◽  
Important Health ◽  
Serious Disease ◽  
Free Ranging

Apilot survey was conducted in 2 districts in Mozambique to determine the most important health problems facing smallholder pig producers. While African swine fever is the most serious disease that affects pigs at all levels of production in Mozambique, it is likely that productivity is reduced by the presence of mange and gastrointestinal parasites, while in traditional systems the conditions are favourable for the development of porcine cysticercosis caused by the pork tapeworm Taenia solium, which poses a health risk to communities. Results of the pilot survey confirmed that, with the exception of African swine fever, ecto- and endoparasites are probably the most important health risks for producers. Porcine cysticercosis is more prevalent among pigs in traditional, free-ranging systems, while mange becomes a serious factor when pigs are permanently confined.

Gastrointestinal parasites of free-ranging colobus monkeys (Colobus angolensis palliatus) in Kwale District, Kenya coast

2006 ◽  
Vol 44 (3) ◽  
pp. 410-412 ◽  
Author(s):  
Sharon Okanga ◽  
Gerald Muchemi ◽  
Nicholas Maingi ◽  
Eddy Mogoa ◽  
Elphas Munene
Keyword(s):  
Gastrointestinal Parasites ◽  
Colobus Monkeys ◽  
Colobus Angolensis ◽  
Free Ranging

The transmission rate of MCMV in house mice in pens: implications for virally vectored immunocontraception

2009 ◽  
Vol 36 (5) ◽  
pp. 386 ◽  
Author(s):  
A. D. Arthur ◽  
C. J. Krebs ◽  
R. P. Pech ◽  
L. N. Farroway ◽  
G. R. Singleton
Keyword(s):  
Transmission Rate ◽  
Wild Mouse ◽  
Fertility Control ◽  
Murine Cytomegalovirus ◽  
House Mice ◽  
Recombinant Viruses ◽  
Economic Thresholds ◽  
Rapid Transmission ◽  
Future Work ◽  
Free Ranging

Pest mammals have severe economic, environmental and social impacts throughout the world. Fertility control could reduce these impacts. Murine cytomegalovirus (MCMV) is being considered as an immunocontraceptive vector to control outbreaks of house mice (Mus domesticus) in Australian grain-growing regions. For successful control, a modified MCMV must transmit at a sufficient rate to keep populations of house mice below acceptable economic thresholds. We used disease models developed previously by using observations of free-ranging wild-mouse populations to assess the transmission rate of two laboratory strains of MCMV (N1 and G4) collected in a previous experiment. Mice contained in pens were deliberately infected with the N1 strain only, or with the N1 strain followed by the G4 strain. If we assume density-dependent transmission, which is the more likely mode of transmission, we found the N1 strain of MCMV transmitted at a rate ~1/300 of the rate of field strains, and hence too slowly for successful virally vectored immunocontraception (VVIC). If transmission was frequency-dependent, the rate of transmission was ~1/3 of the rate of field strains, and hence may allow successful VVIC. The G4 strain transmitted at least as slowly as the N1 strain, and possibly much more slowly; however, we could not determine whether this was an inherent property of the G4 strain or whether it was caused by competition with the N1 strain. Given the reliance of successful VVIC on rapid transmission, we recommend that future work in any VVIC system explicitly quantifies the transmission rate of recombinant viruses relative to field strains, both in the presence and absence of competing strains.

scholarly journals Age-related shapes of the cost of reproduction in vertebrates

2007 ◽  
Vol 3 (6) ◽  
pp. 674-677 ◽  
Author(s):  
G Proaktor ◽  
E.J Milner-Gulland ◽  
T Coulson
Keyword(s):  
Life History ◽  
Exponential Decay ◽  
Theoretical Method ◽  
Cost Of Reproduction ◽  
Frequent Pattern ◽  
Costs Of Reproduction ◽  
Age Related ◽  
Cost Curves ◽  
The Cost ◽  
Related Survival

The shape of the association between age and the cost of reproduction varies across species. However, it is unclear whether there are any general patterns in the way the cost of reproduction varies with life history, taxon or ecological function. Using a simple theoretical method, we identified three characteristic patterns to describe the age-related survival cost of reproduction. The most frequent pattern is an approximately exponential decay (ED) with increasing age. Two additional u-shaped patterns were identified, where the cost of reproduction was higher for young and old individuals compared with intermediate-aged individuals. The majority of these u-shaped curves suggested higher costs of reproduction at older ages (RQ), with the rest suggesting a higher cost at young ages (LQ). While predators were most likely to exhibit ED-shaped cost curves, herbivores were equally likely to exhibit ED and RQ curves; birds were likely to exhibit ED-shaped curves and mammals were split equally between ED and RQ curves. These findings suggest that there may be predictable differences in the age-related shape of the cost of reproduction between species, but further research is required to identify the mechanisms generating such differences.

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