Aging and improving reproductive success in horses: declining residual reproductive value or just older and wiser?

2000 ◽  
Vol 47 (4) ◽  
pp. 243-249 ◽  
Author(s):  
E. Z. Cameron ◽  
W. L. Linklater ◽  
K. J. Stafford ◽  
E. O. Minot
Keyword(s):  
Reproductive Success ◽  
Reproductive Value ◽  
Residual Reproductive Value

scholarly journals Flirting with danger: predation risk interacts with male condition to influence sexual display

2019 ◽  
Vol 30 (5) ◽  
pp. 1265-1272
Author(s):  
Pedro Z de Moraes ◽  
Pedro Diniz ◽  
Esteban Fernandez-Juricic ◽  
Regina H Macedo
Keyword(s):  
High Risk ◽  
Predation Risk ◽  
Video Recording ◽  
Reproductive Value ◽  
Male Response ◽  
Residual Reproductive Value ◽  
Display Behavior ◽  
Sexual Display ◽  
Male Condition ◽  
Risk Of Predation

AbstractSexual signaling coevolves with the sensory systems of intended receivers; however, predators may be unintended receivers of sexual signals. Conspicuous aerial displays in some species may place males at high risk of predation from eavesdropping predators. There are three different hypotheses to explain how signaling males can deal with increased predation risk: (1) males invest in survival by decreasing signal conspicuousness; (2) males invest in reproduction by increasing signal conspicuousness; and (3) male response is condition-dependent according to his residual reproductive value. Here, we used blue-black grassquits (Volatinia jacarina) to test these hypotheses, asking whether males modify leap displays under different levels of predation risk. Grassquit males develop an iridescent nuptial plumage and spend considerable time emitting a multimodal signal: while leaping from a perch, males clap their wings above their heads and emit a high-pitched short song. We exposed males to predator and nonpredator playbacks while video recording their displays. We found interactions between predation risk and 2 male condition variables (ectoparasite infestation and proportion of nuptial plumage coverage) that influenced display behavior. Less parasitized males and those with higher proportion of nuptial plumage showed no change in display behavior, while more parasitized males and those with lower proportion of nuptial plumage increased the vigor of displays under predation risk. In other words, males with low residual reproductive value increased reproductive effort when there was a high risk of extrinsic death. Our study provides some empirical support for the terminal investment hypothesis.

Begging form and growth pattern of nestlings correlate with parental food-allocation patterns in the Horned Lark (Eremophilaalpestris)

2015 ◽  
Vol 93 (4) ◽  
pp. 273-279 ◽  
Author(s):  
Bo Du ◽  
Chang-Jing Liu ◽  
Shi-Jie Bao
Keyword(s):  
Reproductive Success ◽  
Growth Pattern ◽  
Brood Size ◽  
Life History Theory ◽  
Reproductive Value ◽  
Behavioral Strategies ◽  
Tarsus Length ◽  
Food Allocation ◽  
Allocation Patterns ◽  
Horned Lark

Life-history theory assumes that selection favors parents that can maximize their reproductive success via behavioral strategies. As brood size determines the reproductive value of each nestling, parents may adjust their food-allocation patterns according to brood size. We test this assumption in the Horned Lark (Eremophila alpestris (L., 1758)). Our findings revealed that nestling begging forms varied with brood size, by gaping in one-chick broods and postural activity in two- and three-chick broods. Accordingly, parental food-allocation patterns differed in different-sized broods. In one-chick broods, parents increased feeding rates with the gaping duration of nestling. In two-chick broods, parents did not change food-allocation patterns according to nestlings’ begging. In three-chick broods, however, they fed later-hatched nestlings more even when early-hatched nestlings begged more intensely. Horned Larks exhibited obvious sexual differences in parenting style and ability, which resulted in nestlings from two- and three-chick broods changing their begging intensity according to the sex of the provisioning adult. Furthermore, nestling growth pattern diverged with brood sizes, with body mass growing faster in one-chick broods than in two- and three-chick broods. Growth rate of beak gape and tarsus length did not differ significantly among brood sizes, but beak gape was larger and tarsus length was shorter in one-chick broods than in larger broods at fledging. Our results thus support the idea that parents may use food allocation to regulate sibling rivalry, which in turn cause nestlings to beg food in different forms and grow in different patterns so that their reproductive success can be enhanced.

Body mass influences maternal allocation more than parity status for a long-lived cervid mother

2019 ◽  
Vol 100 (5) ◽  
pp. 1459-1465 ◽  
Author(s):  
Eric S Michel ◽  
Stephen Demarais ◽  
Bronson K Strickland ◽  
Jerrold L Belant ◽  
Larry E Castle
Keyword(s):  
Reproductive Success ◽  
Body Mass ◽  
Litter Size ◽  
Reproductive Value ◽  
Lifetime Reproductive Success ◽  
Reproductive Tactics ◽  
High Quality ◽  
Maternal Body ◽  
Individual Offspring ◽  
Maternal Allocation

Abstract Mothers should balance the risk and reward of allocating resources to offspring to optimize the reproductive value of both offspring and mother while maximizing lifetime reproductive success by producing high-quality litters. The reproductive restraint hypothesis suggests maternal allocation should peak for prime-aged mothers and be less for younger mothers such that body condition is not diminished to a level that would jeopardize their survival or future reproductive events. We assessed if reproductive tactics varied by maternal body mass and parity status in captive female white-tailed deer (Odocoileus virginianus) to determine if prime-aged mothers allocate relatively more resources to reproduction than primiparous mothers. Maternal body mass, not parity status, positively affected maternal allocation, with heavier mothers producing both heavy litters and heavy individual offspring. Conversely, maternal body mass alone did not affect litter size, rather the interaction between maternal body mass and parity status positively affected litter size such that maternal body mass displayed a greater effect on litter size for primiparous than multiparous mothers. Our results suggest that heavy white-tailed deer mothers allocate additional resources to current year reproduction, which may be an adaptation allowing mothers to produce high-quality litters and increase their annual reproductive success because survival to the next reproductive attempt is not certain.

scholarly journals Nine-year demography of the black-eared opossum Didelphis aurita (Didelphimorphia: Didelphidae) using life tables

2008 ◽  
Vol 25 (2) ◽  
pp. 206-213 ◽  
Author(s):  
Maja Kajin ◽  
Rui Cerqueira ◽  
Marcus V. Vieira ◽  
Rosana Gentile
Keyword(s):  
Intrinsic Rate ◽  
Life Tables ◽  
Reproductive Value ◽  
Intrinsic Rate Of Increase ◽  
Population Parameters ◽  
Age Classes ◽  
Model Species ◽  
Residual Reproductive Value ◽  
Rate Of Increase ◽  
Didelphis Aurita

A population of the black-eared opossum, Didelphis aurita Wied-Neuwied 1826, was studied during 1997-2006 by capture-mark-recapture in the Atlantic Forest in the state of Rio de Janeiro. Cohorts were established with females marked still in the pouch, classified into five age classes. Population parameters were estimated using life tables. Survival was type III and mortality was greatest in age classes I and II, just after weaning. Fecundity was inversely correlated with survival, reproductive value was inversely correlated with mortality and residual reproductive value was inversely correlated with fecundity. The intrinsic rate of increase was always close to zero and tended to be slightly negative. The black-eared opossum can be considered a good model species for this type of study.

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