Reproductive Effort and Terminal Investment in Iteroparous Animals

1984 ◽  
Vol 123 (2) ◽  
pp. 212-229 ◽  
Author(s):  
T. H. Clutton-Brock
Keyword(s):  
Reproductive Effort ◽  
Terminal Investment

scholarly journals Amphibians with infectious disease increase their reproductive effort: evidence for the terminal investment hypothesis

Open Biology ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 150251 ◽  
Author(s):  
Laura A. Brannelly ◽  
Rebecca Webb ◽  
Lee F. Skerratt ◽  
Lee Berger
Keyword(s):  
Disease Resistance ◽  
Reproductive Effort ◽  
Batrachochytrium Dendrobatidis ◽  
Population Level ◽  
Life History Trait ◽  
Terminal Investment ◽  
Frog Species ◽  
Selection For ◽  
Declining Species ◽  
Investment Hypothesis

Mounting an immune response to fight disease is costly for an organism and can reduce investment in another life-history trait, such as reproduction. The terminal investment hypothesis predicts that an organism will increase reproductive effort when threatened by disease. The reproductive fitness of amphibians infected with the deadly fungal pathogen Batrachochytrium dendrobatidis ( Bd ) is largely unknown. In this study, we explored gametogenesis in two endangered and susceptible frog species, Pseudophryne corroboree and Litoria verreauxii alpina. Gametogenesis, both oogenesis and spermatogenesis, increased when animals were experimentally infected with Bd . In P. corroboree , infected males have thicker germinal epithelium, and a larger proportion of spermatocytes. In L. v. alpina , infected males had more spermatic cell bundles in total, and a larger proportion of spermatozoa bundles. In female L. v. alpina , ovaries and oviducts were larger in infected animals, and there were more cells present within the ovaries. Terminal investment has consequences for the evolution of disease resistance in declining species. If infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population-level selection for disease resistance will be minimized.

Older conservatives: reproduction in female Alpine chamois (Rupicapra rupicapra) is increasingly risk-averse with age

2016 ◽  
Vol 94 (5) ◽  
pp. 311-321 ◽  
Author(s):  
A. Morin ◽  
M. Rughetti ◽  
S. Rioux-Paquette ◽  
M. Festa-Bianchet
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Risk Averse ◽  
Costs Of Reproduction ◽  
Rupicapra Rupicapra ◽  
Terminal Investment ◽  
Age Dependent ◽  
Alpine Chamois ◽  
Old Females ◽  
Investment Hypothesis

In long-lived mammals, costs of reproduction may vary with age. The terminal investment hypothesis predicts greater reproductive effort as females approach the end of their life expectancy. We monitored 97 individually marked female Alpine chamois (Rupicapra rupicapra (L., 1758)) between 2007 and 2013 to determine how age-specific reproduction affected body mass and subsequent reproductive success. We captured and weighed females between April and August and monitored reproductive success from April to October through mother–kid associations. Reproductive success was strongly age-dependent and peaked at 70% for prime-aged females (4–7 years). Reproductive senescence began at 8 years, earlier than reported by other studies of ungulates. There was no clear evidence of reproductive costs in any age class. Reproductive success was very heterogeneous for old females, suggesting variability in the onset of senescence. Old females were less likely to reproduce in poor years despite being heavier than prime-aged females, suggesting reproductive restraint in late life rather than terminal investment. Female mass remained stable from May to August with no effect of lactation. Our results suggest that chamois reproductive strategy becomes increasingly conservative with age, resulting in no detectable costs of reproduction.

Age-Specific Changes in Reproductive Effort and Terminal Investment in Female Nile Lechwe

2009 ◽  
Vol 90 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Fred B. Bercovitch ◽  
Caroline Pitt Loomis ◽  
Randy G. Rieches
Keyword(s):  
Reproductive Effort ◽  
Terminal Investment

scholarly journals Senescent birds redouble reproductive effort when ill: confirmation of the terminal investment hypothesis

2006 ◽  
Vol 273 (1593) ◽  
pp. 1443-1448 ◽  
Author(s):  
Alberto Velando ◽  
Hugh Drummond ◽  
Roxana Torres
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Initial Increase ◽  
Male Reproductive Success ◽  
Age Classes ◽  
Theoretical Idea ◽  
Sula Nebouxii ◽  
Terminal Investment ◽  
Survival And Reproduction ◽  
Investment Hypothesis

This study reports an experimental confirmation of the terminal investment hypothesis, a longstanding theoretical idea that animals should increase their reproductive effort as they age and their prospects for survival and reproduction decline. Previous correlational and experimental attempts to test this hypothesis have yielded contradictory results. In the blue-footed booby, Sula nebouxii , a long-lived bird, after initial increase, male reproductive success declines progressively with age. Before laying, males of two age classes were challenged with lipopolysaccharide to elicit an immune response, which induced symptoms of declining survival prospects. Reproductive success of immune-challenged mature males fell, while that of immune-challenged old males showed a 98% increase. These results demonstrate that senescent males with poor reproductive prospects increase their effort when those prospects are threatened, whereas younger males with good reproductive prospects do not.

scholarly journals The influence of male age and simulated pathogenic infection on producing a dishonest sexual signal

2012 ◽  
Vol 279 (1748) ◽  
pp. 4740-4746 ◽  
Author(s):  
Emily K. Copeland ◽  
Kenneth M. Fedorka
Keyword(s):  
Reproductive Effort ◽  
Reproductive Value ◽  
Female Fitness ◽  
Sexual Signal ◽  
Terminal Investment ◽  
Male Age ◽  
Residual Reproductive Value ◽  
Male Reproductive Effort ◽  
Allonemobius Socius ◽  
Pathogenic Infection

In recent years, studies have shown that reproductive effort decelerates in response to pathogenic infection. If infection substantially reduces a host's residual reproductive value (RRV), however, then an acceleration of effort may instead occur (e.g. terminal investment). Reproductive acceleration would theoretically allow hosts to maintain or exaggerate their sexual signal upon infection. This would create a deceptive message from the perspective of the chooser, who may unwittingly copulate with an infected mate to their detriment. Using the cricket Allonemobius socius , we assessed the potential for reduced RRV to accelerate male reproductive effort and create a dishonest signal. RRV was manipulated through male age and simulated pathogenic insult. Reproductive effort was measured as calling song energetics, mating success, latency to mate and nuptial gift size. We show that males adopted either an accelerated or decelerated reproductive strategy upon infection, and that this decision was probably mediated by RRV. Moreover, males who accelerated their effort produced a dishonest signal by increasing their song energetics while providing fewer paternal resources (i.e. smaller gifts). Our study is one of the few to document the existence of dishonest signals and relate dishonesty to a potential reduction in female fitness, underscoring the conflict inherent in sexual reproduction.

scholarly journals Ant queens increase their reproductive efforts after pathogen infection

2017 ◽  
Vol 4 (7) ◽  
pp. 170547 ◽  
Author(s):  
Julia Giehr ◽  
Anna V. Grasse ◽  
Sylvia Cremer ◽  
Jürgen Heinze ◽  
Alexandra Schrempf
Keyword(s):  
Social Insect ◽  
Reproductive Effort ◽  
Reproductive Rate ◽  
Egg Laying ◽  
Reproductive Value ◽  
Reproductive Senescence ◽  
Terminal Investment ◽  
Investment In Reproduction ◽  
First Time ◽  
Investment Hypothesis

Infections with potentially lethal pathogens may negatively affect an individual's lifespan and decrease its reproductive value. The terminal investment hypothesis predicts that individuals faced with a reduced survival should invest more into reproduction instead of maintenance and growth. Several studies suggest that individuals are indeed able to estimate their body condition and to increase their reproductive effort with approaching death, while other studies gave ambiguous results. We investigate whether queens of a perennial social insect (ant) are able to boost their reproduction following infection with an obligate killing pathogen. Social insect queens are special with regard to reproduction and aging, as they outlive conspecific non-reproductive workers. Moreover, in the ant Cardiocondyla obscurior , fecundity increases with queen age. However, it remained unclear whether this reflects negative reproductive senescence or terminal investment in response to approaching death. Here, we test whether queens of C. obscurior react to infection with the entomopathogenic fungus Metarhizium brunneum by an increased egg-laying rate. We show that a fungal infection triggers a reinforced investment in reproduction in queens. This adjustment of the reproductive rate by ant queens is consistent with predictions of the terminal investment hypothesis and is reported for the first time in a social insect.

High Reproductive Effort and Low Recruitment Rates of European Beech: Is There a Limit for the Superior Competitor?

2015 ◽  
Vol 63 (2) ◽  
pp. 198-212 ◽  
Author(s):  
Jerzy Szwagrzyk ◽  
Georg Gratzer ◽  
Hanna Stępniewska ◽  
Janusz Szewczyk ◽  
Bojana Veselinovic
Keyword(s):  
Reproductive Effort ◽  
European Beech ◽  
High Reproductive Effort
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