Biology subjects

Moorad, J.

Publications and source records attributed to Moorad, J..

5 recordsLinked to original sources

bioRxiv2025

Mutation accumulation underpins evolution of lifespan extension by dietary restriction

Dietary restriction (DR) extends lifespan in animals and plants, but its evolutionary causes are elusive. Adaptive hypotheses posit that DR extends lifespan because organisms reallocate resources from reproduction to survival ( disposable soma) or recycle cellular waste to maximize either their immediate reproduction ( nutrient recycling) or survival ( clean cupboards). We developed an experimental paradigm that tricks Caenorhabditis elegans nematodes into increasing their reproductive effort under DR via food odour, thus allowing us to test these hypotheses. We found that experimentally increased reproduction under DR does not affect immediate or long-term survival benefits compared to DR animals that did not reproduce, thus refuting all three adaptive hypotheses. Our data suggest that a large part of suppressed fertility under DR is a result of organisms refraining from producing offspring in a poor environment. We developed a model based on Hamiltonian forces of selection to show that lifespan extension under DR evolves because DR suppresses fertility, directly increasing selection against mortality in DR environment. Our analytical approach suggests that DR-driven lifespan extension can evolve under a broader range of conditions not previously anticipated, such as a relaxed need for physiological or genetic trade-offs. Instead, we show how reduced survival on plentiful food can evolve via mutation accumulation.

evolutionary biology↗

bioRxiv2022

Genetic variance and indirect genetic effects for affiliative social behavior in a wild primate

Affiliative social behaviors are linked to fitness components in multiple species. However, the role of genetic variance in shaping affiliative social behaviors remains largely unknown, limiting our understanding of how these behaviors can respond to natural selection. Here, we employed the animal model to estimate both environmental and genetic sources of variance and covariance in grooming behavior in the well-studied Amboseli baboon population in Kenya. We found that grooming given, grooming received, and total grooming all are similarly heritable (h2=0.22, h2=0.16, and h2=0.26 respectively), and that rank and the presence of kin contribute to environmental variance. We detected small but measurable indirect genetic effects of partner identity on the amount of grooming given within dyadic grooming partnerships. The genetic correlation between grooming given and grooming received was exceptionally strong and positive (R=0.94 {+/-} 0.12), and the indirect and direct genetic effects for grooming given were also strongly positively correlated (R=0.86 {+/-} 0.06). Our results provide insight into the evolvability of affiliative behavior in wild animals, including the possibility for correlations between direct and indirect genetic effects to accelerate the response to selection. As such they provide novel information about the genetic architecture of social behavior in nature, with important implications for the evolution of cooperation and reciprocity.

evolutionary biology↗

bioRxiv2022

The distribution of the Lansing Effect across animal species

Maternal senescence is a reduction in individual performance associated with an increase in its mothers age at conception. When manifested on adult lifespan, this is known as the Lansing Effect. Single-species studies report both maternal age-related increases and decreases in adult lifespan, but no comprehensive review of the literature has yet determined if the Lansing Effect is a widespread phenomenon. To address this knowledge gap, we performed a meta-analysis of maternal aging rates taken from all available published studies. We recovered 74 estimates from 20 studies representing 14 species. All studies taken together suggest a propensity for a Lansing Effect with an estimated average effect of maternal age on adult lifespan of between -22% to -17% (the lifespan response to an increase in maternal age expressed in the same time units), depending upon our specific choice of model. We failed to find a significant effect of animal class or insect order, but given the oversampling of insect species in the published literature and the paucity of vertebrate studies, we infer that only rotifers and insects demonstrate a tendency for expressing the phenomenon.

evolutionary biology↗

bioRxiv2021

Biparental age effects in the burying beetle Nicrophorus vespilloides

Parental age at reproduction influences offspring size and survival by affecting prenatal and postnatal conditions in a wide variety of species, including humans. However, most investigations into this manifestation of ageing focus upon maternal age effects; the effects of paternal age and interactions between maternal and paternal age are often neglected. Furthermore, even when maternal age effects are studied, pre- and postnatal effects are confounded. Using a cross-fostered experimental design, we investigated the joint effects of paternal and pre- and postnatal maternal ages on numerous offspring outcomes in a laboratory population of a species of burying beetle, Nicrophorus vespilloides. When we correct our tests for significance for multiple comparisons, we found no clear evidence for any parental effect senescence acting on egg size, larval weight, or larval survival. Nor did we find a statistical effect of paternal or egg producer age on the outcomes of foster mothers as measured by weight change experienced during caregiving. These findings are consistent with recent negative results reported in a similar study of N. vespilloides maternal age effects while also expanding these to other offspring traits and to paternal age effects. We discuss how the peculiar life history of this species may promote selection to resist the evolution of parental age effects, and how this might have influenced our ability to detect senescence.

evolutionary biology↗

bioRxiv2018

Evaluating the diversity of maternal age effects upon neonatal survival across animal species

Maternal effect senescence is the detrimental effect of increased maternal age on offspring performance. Despite much recent interest given to describing this phenomenon, its origins and distribution across the tree-of-life are poorly understood. We find that age affects neonatal survival in 83 of 90 studies across 51 species, but we observed a puzzling difference between groups of animal species. Amongst wild bird populations, the average effect of age was only -0.7% per standardized unit of increasing age, but maternal effects clearly senesced in laboratory invertebrates (-67.1%) and wild mammals (-57.8%). Comparisons amongst demographic predictions derived from evolutionary theory and conventional demographic models suggest that natural selection has shaped maternal effect senescence in the natural world. These results emphasize both the general importance of maternal age effects and the potential for evolutionary genetics to provide a valuable framework for understanding the diversity of this manifestation of ageing in animal species.

evolutionary biology↗