Testing Williams’ prediction: reproductive effort versus residual reproductive value (RRV)

2010 ◽  
Vol 88 (9) ◽  
pp. 900-904
Author(s):  
F. Stephen Dobson ◽  
Pierre Jouventin
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Positive Association ◽  
Positive Influence ◽  
Life Cycles ◽  
Reproductive Value ◽  
Residual Reproductive Value ◽  
Trade Offs ◽  
Survival And Reproduction

Williams (1966; Am. Nat. 100(916): 687–690) furthered R.A. Fisher’s concept of reproductive value by breaking it into two components: (1) current reproduction and (2) residual reproductive value (RRV, the summed product of survival and reproduction over the rest of the lifespan). He predicted a negative correlation of measures of these two components among species, and this prediction led in part to the idea of trade-offs in life-history theory. We tested Williams’ prediction with 24 species of albatrosses and petrels (order Procellariiformes), species with a great range of body sizes and all laying only one egg at a time (like humans, highly iteroparous). Two measures of reproductive investment were not negatively correlated with RRV. Adjusting data for body mass and phylogeny resulted in significant positive associations. In addition, any measure of annual parental allocation to reproduction (once adjusted for body size) should give a positive association with RRV as shown by a simple simulation model that assumes a highly iteroparous life cycle. Under such life cycles, Williams’ prediction confounds the positive influence of reproduction on both current investment and RRV. Principles of life-history theory, however, do not require re-evaluation, as this particular prediction can in at least some cases be internally inconsistent.

Effect of body size, age and timing of breeding on clutch and egg size of female Eastern Gray Treefrogs, Hyla versicolor

2021 ◽  
pp. 1-11
Author(s):  
Gerlinde Höbel ◽  
Robb Kolodziej ◽  
Dustin Nelson ◽  
Christopher White
Keyword(s):  
Life History ◽  
Egg Size ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Ecological Factors ◽  
Hyla Versicolor ◽  
Growth And Survival ◽  
Factors Affecting ◽  
Trade Offs ◽  
Gray Treefrogs

Abstract Information on how organisms allocate resources to reproduction is critical for understanding population dynamics. We collected clutch size (fecundity) and egg size data of female Eastern Gray Treefrogs, Hyla versicolor, and examined whether observed patterns of resource allocation are best explained by expectations arising from life history theory or by expected survival and growth benefits of breeding earlier. Female Hyla versicolor showed high between-individual variation in clutch and egg size. We did not observe maternal allocation trade-offs (size vs number; growth vs reproduction) predicted from life history theory, which we attribute to the large between-female variation in resource availability, and the low survival and post-maturity growth rate observed in the study population. Rather, clutches are larger at the beginning of the breeding season, and this variation in reproductive investment aligns with seasonal variation in ecological factors affecting offspring growth and survival.

Life History Adaptation in Prey

2018 ◽  
pp. 323-346
Author(s):  
Gary A. Wellborn
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Value ◽  
Offspring Size ◽  
Selective Predation ◽  
Antipredator Defense ◽  
Trade Offs ◽  
History Evolution

Predation is a powerful agent of life history evolution in prey species, as demonstrated in diverse examples in crustaceans. Ubiquitous size- and age-selective predation mediates trade-offs among reproductive effort, survival, and growth, which cause evolution of constitutive and phenotypically plastic shifts in age and size at maturity. In accord with predictions of life history theory, comparative studies demonstrate that contrasting forms of selective predation generate divergent evolutionary changes in age- and size-specific allocation of reproductive effort within populations and species. Predation risk also influences egg and offspring size, and some crustaceans exhibit phenotypic plasticity in offspring size in response to chemical cues of predators. Because age-selective predation impacts the relative benefits of earlier versus later reproductive investment, predation may also shape senescence and life span of crustaceans. Additionally, individual differences in risk-taking behavior, sometimes termed “personalities,” have been examined in several crustaceans, and these may arise through among-individual variation in reproductive value. Finally, in some crustacean groups limb autotomy is a common, but costly, antipredator defense, and life history perspectives on autotomy suggest individuals may balance costs and benefits during predator encounters. Much of our understanding of predation’s role in life history evolution of prey derives from studies of crustaceans, and these organisms continue to be promising avenues to elucidate mechanisms of life history evolution.

scholarly journals Cyclical environments drive variation in life history strategies: a general theory of cyclical phenology

2018 ◽  
Author(s):  
John S. Park
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Life History Strategies ◽  
Life History Variation ◽  
Trade Offs ◽  
Overwhelming Evidence ◽  
Phenological Shifts

ABSTRACTCycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons— are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life history evolution in cyclical environments are still not well understood. Here I build a demographic framework and ask how life history strategies optimize fitness when the environment perturbs a structured population cyclically, and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life history trade-offs in a marine intertidal copepod T. californicus successfully predicted the shape of life history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life history diversity explained by theory and providing a basis for adaptive phenology.

scholarly journals Effects of immune challenge on expression of life-history and immune trait expression in sexually reproducing metazoans—a meta-analysis

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
M. Nystrand ◽  
D. K. Dowling
Keyword(s):  
Life History ◽  
Host Response ◽  
Life History Theory ◽  
Meta Analysis ◽  
Reproductive Traits ◽  
Phenotypic Trait ◽  
Immune Challenge ◽  
Negative Effects ◽  
Trade Offs ◽  
Survival And Reproduction

Abstract Background Life-history theory predicts a trade-off between investment into immune defence and other fitness-related traits. Accordingly, individuals are expected to upregulate their immune response when subjected to immune challenge. However, this is predicted to come at the expense of investment into a range of other traits that are costly to maintain, such as growth, reproduction and survival. Currently, it remains unclear whether the magnitude of such costs, and trade-offs involving immune investment and other traits, manifests consistently across species and sexes. To address this, we conducted a meta-analysis to investigate how changes in sex, ontogenetic stage and environmental factors shape phenotypic trait expression following an immune challenge. Results We explored the effects of immune challenge on three types of traits across sexually reproducing metazoans: life-history, morphological and proximate immune traits (235 effect sizes, 53 studies, 37 species [21 invertebrates vs. 16 vertebrates]). We report a general negative effect of immune challenge on survival and reproduction, a positive effect on immune trait expression, but no effect on morphology or development time. The negative effects of immune challenge on reproductive traits and survival were larger in females than males. We also report a pronounced effect of the immune treatment agent used (e.g. whether the treatment involved a live pathogen or not) on the host response to immune challenge, and find an effect of mating status on the host response in invertebrates. Conclusion These results suggest that costs associated with immune deployment following an immune challenge are context-dependent and differ consistently in their magnitude across the sexes of diverse taxonomic lineages. We synthesise and discuss the outcomes in the context of evolutionary theory on sex differences in life-history and highlight the need for future studies to carefully consider the design of experiments aimed at disentangling the costs of immune deployment.

scholarly journals Cyclical environments drive variation in life-history strategies: a general theory of cyclical phenology

2019 ◽  
Vol 286 (1898) ◽  
pp. 20190214 ◽  
Author(s):  
John S. Park
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Natural Populations ◽  
Life History Evolution ◽  
Life Cycles ◽  
Life History Strategies ◽  
Life History Variation ◽  
Trade Offs ◽  
Overwhelming Evidence ◽  
Phenological Shifts

Cycles, such as seasons or tides, characterize many systems in nature. Overwhelming evidence shows that climate change-driven alterations to environmental cycles—such as longer seasons—are associated with phenological shifts around the world, suggesting a deep link between environmental cycles and life cycles. However, general mechanisms of life-history evolution in cyclical environments are still not well understood. Here, I build a demographic framework and ask how life-history strategies optimize fitness when the environment perturbs a structured population cyclically and how strategies should change as cyclicality changes. I show that cycle periodicity alters optimality predictions of classic life-history theory because repeated cycles have rippling selective consequences over time and generations. Notably, fitness landscapes that relate environmental cyclicality and life-history optimality vary dramatically depending on which trade-offs govern a given species. The model tuned with known life-history trade-offs in a marine intertidal copepod Tigriopus californicus successfully predicted the shape of life-history variation across natural populations spanning a gradient of tidal periodicities. This framework shows how environmental cycles can drive life-history variation—without complex assumptions of individual responses to cues such as temperature—thus expanding the range of life-history diversity explained by theory and providing a basis for adaptive phenology.

scholarly journals Greater reproductive investment, but shorter lifespan, in agrosystem than in natural-habitat toads

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3791 ◽  
Author(s):  
Francisco Javier Zamora-Camacho ◽  
Mar Comas
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Prey Availability ◽  
Natural Habitat ◽  
Reproductive Investment ◽  
Emerging Diseases ◽  
Life Cycles ◽  
Habitat Alterations ◽  
Individual Fitness ◽  
Energy Trade

Global amphibian decline is due to several factors: habitat loss, anthropization, pollution, emerging diseases, and global warming. Amphibians, with complex life cycles, are particularly susceptible to habitat alterations, and their survival may be impaired in anthropized habitats. Increased mortality is a well-known consequence of anthropization. Life-history theory predicts higher reproductive investment when mortality is increased. In this work, we compared age, body size, and different indicators of reproductive investment, as well as prey availability, in natterjack toads (Epidalea calamita) from agrosystems and adjacent natural pine groves in Southwestern Spain. Mean age was lower in agrosystems than in pine groves, possibly as a consequence of increased mortality due to agrosystem environmental stressors. Remarkably, agrosystem toads were larger despite being younger, suggesting accelerated growth rate. Although we detected no differences in prey availability between habitats, artificial irrigation could shorten aestivation in agrosystems, thus increasing energy trade. Moreover, agrosystem toads exhibited increased indicators of reproductive investment. In the light of life-history theory, agrosystem toads might compensate for lesser reproductive events—due to shorter lives—with a higher reproductive investment in each attempt. Our results show that agrosystems may alter demography, which may have complex consequences on both individual fitness and population stability.

The costs of reproduction in tree swallows (Tachycineta bicolor)

1991 ◽  
Vol 69 (10) ◽  
pp. 2540-2547 ◽  
Author(s):  
Nathaniel T. Wheelwright ◽  
Joanna Leary ◽  
Caragh Fitzgerald
Keyword(s):  
Life History ◽  
Clutch Size ◽  
Brood Size ◽  
Life History Theory ◽  
Tachycineta Bicolor ◽  
Laying Date ◽  
Tree Swallows ◽  
Costs Of Reproduction ◽  
Return Rates ◽  
Trade Offs

We investigated the effect of brood size on nestling growth and survival, parental survival, and future fecundity in tree swallows (Tachycineta bicolor) over a 4-year period (1987–1990) in an effort to understand whether reproductive trade-offs limit clutch size in birds. In addition to examining naturally varying brood sizes in a population on Kent Island, New Brunswick, Canada, we experimentally modified brood sizes, increasing or decreasing the reproductive burdens of females by two offspring. Unlike previous studies, broods of the same females were enlarged or reduced in up to 3 successive years in a search for evidence of cumulative costs of reproduction that might go undetected by a single brood manipulation. Neither observation nor experiment supported the existence of a trade-off between offspring quality and quantity, in contrast with the predictions of life-history theory. Nestling wing length, mass, and tarsus length were unrelated to brood size. Although differences between means were in the direction predicted, few differences were statistically significant, despite large sample sizes. Nestlings from small broods were no more likely to return as breeding adults than nestlings from large broods, but return rates of both groups were very low. Parental return rates were also independent of brood size, and there was no evidence of a negative effect of brood size on future fecundity (laying date, clutch size). Reproductive success, nestling size, and survival did not differ between treatments for females whose broods were manipulated in successive years. Within the range of brood sizes observed in this study, the life-history costs of feeding one or two additional nestlings in tree swallows appear to be slight and cannot explain observed clutch sizes. Costs not measured in this study, such as the production of eggs or postfledging parental care, may be more important in limiting clutch size in birds.

scholarly journals Enzymatic antioxidants but not baseline glucocorticoids mediate the reproduction–survival trade-off in a wild bird

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182141 ◽  
Author(s):  
Stefania Casagrande ◽  
Michaela Hau
Keyword(s):  
Life History ◽  
Body Condition ◽  
Redox State ◽  
Reproductive Investment ◽  
Redox System ◽  
Reactive Oxygen Metabolites ◽  
Enzymatic Antioxidants ◽  
Trade Off ◽  
Trade Offs ◽  
Nest Provisioning

The trade-off between reproductive investment and survival is central to life-history theory, but the relative importance and the complex interactions among the physiological mechanisms mediating it are still debated. Here we experimentally tested whether baseline glucocorticoid hormones, the redox system or their interaction mediate reproductive investment–survival trade-offs in wild great tits ( Parus major ). We increased the workload of parental males by clipping three feathers on each wing, and 5 days later determined effects on baseline corticosterone concentrations (Cort), redox state (reactive oxygen metabolites, protein carbonyls, glutathione peroxidase [GPx], total non-enzymatic antioxidants), body mass, body condition, reproductive success and survival. Feather-clipping did not affect fledgling numbers, chick body condition, nest provisioning rates or survival compared with controls. However, feather-clipped males lost mass and increased both Cort and GPx concentrations. Within feather-clipped individuals, GPx increases were positively associated with reproductive investment (i.e. male nest provisioning). Furthermore, within all individuals, males that increased GPx suffered reduced survival rates. Baseline Cort increases were related to mass loss but not to redox state, nest provisioning or male survival. Our findings provide experimental evidence that changes in the redox system are associated with the trade-off between reproductive investment and survival, while baseline Cort may support this trade-off indirectly through a link with body condition. These results also emphasize that plastic changes in individuals, rather than static levels of physiological signals, may mediate life-history trade-offs.

Life histories of North American game birds: a reanalysis

1988 ◽  
Vol 66 (8) ◽  
pp. 1906-1912 ◽  
Author(s):  
Todd W. Arnold
Keyword(s):  
Life History ◽  
North American ◽  
Life Histories ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Cost Of Reproduction ◽  
Reproductive Value ◽  
Trade Offs ◽  
Game Birds ◽  
The Cost

Recently, Zammuto (R. M. Zammuto. 1986. Can. J. Zool. 64: 2739–2749) suggested that North American game birds exhibited survival–fecundity trade-offs consistent with the "cost of reproduction" hypothesis. However, there were four serious problems with the data and the analyses that Zammuto used: (i) the species chosen for analysis ("game birds") showed little taxonomic or ecological uniformity, (ii) the measures of future reproductive value (maximum longevity) were severely biased by unequal sample sizes of band recoveries, (iii) the measures of current reproductive effort (clutch sizes) were inappropriate given that most of the birds analyzed produce self-feeding precocial offspring, and (iv) the statistical units used in the majority of analyses (species) were not statistically independent with respect to higher level taxonomy. After correcting these problems, I found little evidence of survival–fecundity trade-offs among precocial game birds, and I attribute most of the explainable variation in life-history traits of these birds to allometry, phylogeny, and geography.

scholarly journals Cuckoos, cowbirds and hosts: adaptations, trade-offs and constraints

2006 ◽  
Vol 362 (1486) ◽  
pp. 1873-1886 ◽  
Author(s):  
Oliver Krüger
Keyword(s):  
Life History ◽  
Brood Parasitism ◽  
Reproductive Strategies ◽  
Life History Theory ◽  
Model Systems ◽  
Life History Strategies ◽  
Host System ◽  
Brood Parasites ◽  
Trade Offs ◽  
Evolution Of Life

The interactions between brood parasitic birds and their host species provide one of the best model systems for coevolution. Despite being intensively studied, the parasite–host system provides ample opportunities to test new predictions from both coevolutionary theory as well as life-history theory in general. I identify four main areas that might be especially fruitful: cuckoo female gentes as alternative reproductive strategies, non-random and nonlinear risks of brood parasitism for host individuals, host parental quality and targeted brood parasitism, and differences and similarities between predation risk and parasitism risk. Rather than being a rare and intriguing system to study coevolutionary processes, I believe that avian brood parasites and their hosts are much more important as extreme cases in the evolution of life-history strategies. They provide unique examples of trade-offs and situations where constraints are either completely removed or particularly severe.

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