Biology subjects

Santos, E. S. A.

Publications and source records attributed to Santos, E. S. A..

5 recordsLinked to original sources

bioRxiv2026

Allonursing (Co-BreeD): Its prevalence, functions and hypotheses across mammals and human cultures

Allonursing, where dependent young are nursed by females other than their mothers, has been observed across diverse mammalian species and human cultures. Yet, the proximate functions underlying this seemingly altruistic behaviour, and its benefits for the offspring, the mother, and the nursing allomother, remain poorly understood. To facilitate testing hypotheses concerning these questions, we compiled the to date largest allonursing dataset from wild populations (N = 101 species, including 133 populations and 5 human cultures). Using this dataset, we (i) map the taxonomic distribution of allonursing, thereby expanding the list of mammal species qualified as cooperative breeders by 17 additional species, (ii) differentiate cases of non-voluntary from voluntary allonursing and consequently reject the hypothesis that milk stealing explains regular allonursing in most species, (iii) quantify the within-population extent of allonursing to assess its significance across species and evaluate the energy/time saved for mothers, (iv) use phylogenetically controlled analyses to revisit the association between allonursing and polytocy (i.e., litter size >1), and provide an alternative explanation for this association. We conclude by proposing that allonursing has multiple functions, with the most empirically supported ones being provisioning and insurance against maternal loss. Finally, the presented AlloNursing dataset complements the Cooperative-Breeding Database (Co-BreeD) to further expand this integrative resource for cooperative breeding research.

animal behavior and cognition↗

bioRxiv2024

Defensive symbionts provide high protection against natural enemies at low cost to hosts: a meta-analysis

Defensive endosymbionts (i.e., endosymbionts that protect hosts against natural enemies) are widespread in terrestrial arthropods, especially insects. Protection against natural enemies may contribute to their successful spread in nature. However, the outcome of host-symbiont interactions (mutualism or parasitism) depend on the balance between the costs and benefits of the interaction and on the ecological conditions experienced by the host, such as the presence or absence of natural enemies. Here, we conducted a meta-analysis to quantitatively assess the costs and benefits of symbiont-mediated protection in terrestrial arthropods. We gathered approximately 3,425 effect sizes from 246 studies. Our results show that in the presence of natural enemies (i.e., hosts infected with pathogens or parasites), symbionts provide protection, positively affecting the fitness of hosts. In the absence of natural enemies, symbionts caused little reduction in host fitness. Overall, symbiont-mediated protection was 7.1 times stronger than the cost observed in the absence of natural enemies, indicating strong protection and little evidence of substantial fitness costs to hosts. Natural enemies attacking symbiont-infected hosts had substantial reduction in their fitness. Moreover, the level of protection and cost for both hosts and natural enemies varies between the fitness components, host families, symbiont species, and natural enemy group. Our results reveal a broad symbiont-mediated protection with little evidence of substantial costs associated, which may help explain the successful spread of symbionts in wild arthropod populations.

ecology↗

bioRxiv2018

Habitat structure drives the evolution of aerial displays in birds

Physical properties of the environment may shape signalling traits by determining how effective the signals are in affecting the behaviour of other individuals. Evidence abounds of signalling environment driving the evolution of colours and sounds, but little is known about its influence upon gestural displays. Here, we performed a continent-wide phylogenetic comparative analysis to test the hypothesis that habitat structure drives the evolution of aerial sexual displays in passerine birds. We found that aerial displays are seven times more likely to evolve in open habitats than in forests, likely as a result of physical properties that allow aerial displays to transmit more broadly in open habitats. Our results provide an emblematic example of how environmental factors may help predict the direction of evolution of otherwise unpredictable sexual traits. The broader range of aerial displays in open habitats may also mean that females can sample more males, potentially leading to more intense sexual selection over open-habitat, aerial-displaying males.

evolutionary biology↗

bioRxiv2017

Helpers increase daily survival rate of Southern Lapwing (Vanellus chilensis) nests during the incubation stage

Cooperative breeding is characterized by reproduction in the presence of helpers. What impact these helpers have on the reproductive success of group members is one of the long-standing questions in the cooperative breeding literature. In cooperative species, helpers are known to provide benefits during multiple stages or at a particular stage of the reproductive cycle. The aim of this study was to investigate whether helpers increased the daily survival rate of nests during the incubation stage in the Southern Lapwing (Vanellus chilensis), a crested plover with a cooperative breeding system. Southern Lapwings have a variable mating system, with some breeding groups composed of unassisted pairs, and others that breed in the presence of helpers. Our best supported model indicated a positive effect of the presence of helpers on the daily survival rate of nests, leading to a probability of nest success (i.e., survival until hatching) of 83%, compared to 51% for nests of unassisted pairs. But a null model had a similar model weight as the best supported model and was the second-best model. Our study provides evidence that helpers influence egg survival during the egg-incubation stage, which could influence the fitness of breeders.

animal behavior and cognition↗

bioRxiv2017

Facultative adjustment of paternal care in the face of female infidelity in dunnocks

A much-debated issue is whether or not males should reduce parental care when they lose paternity (i.e. the certainty of paternity hypothesis). While there is general support for this relationship across species, within-population evidence is still contentious. Among the main reasons behind such problem is the confusion discerning between-from within-individual patterns. Here, we tested this hypothesis empirically by investigating the parental care of male dunnocks (Prunella modularis) in relation to paternity. We used a thorough dataset of observations in a wild population, genetic parentage, and a within-subject centring statistical approach to disentangle paternal care adjustment within-male and between males. We found support for the certainty of paternity hypothesis, as there was evidence for within-male adjustment in paternal care when socially monogamous males lost paternity to extra-pair sires. There was little evidence of a between-male effect overall. Our findings show that monogamous males adjust paternal care when paired to the same female partner. We also show that - in monogamous broods - the proportion of provisioning visits made by males yields fitness benefits in terms of fledging success. Our results suggest that socially monogamous females that engage in extra-pair behaviour may suffer fitness costs, as their partners reduction in paternal care can negatively affect fledging success.

animal behavior and cognition↗