Figure - available from: Communications Biology
This content is subject to copyright. Terms and conditions apply.
![Matrix population models
a Population growth rates (λ, [95% CI]) are plotted for season- and density-specific matrix population models that were parameterised with the estimates from the MSCMR-models in grey. In blue and green, λ estimates from matrix models with the same survival and breeding values are shown, but the probability to breed communally is fixed to 1 (blue) or 0 (green), simulating populations with females using only one of the two tactics. b Sensitivities [95% CI] for the probability to breed solitarily during the breeding season at two different population densities. The Matrix population models were again parameterised with the estimates from the MSCMR-model (see Table S3, SI).](publication/359895471/figure/fig3/AS:1144233901735946@1649818029890/Matrix-population-models-a-Population-growth-rates-l-95-CI-are-plotted-for-season.png)
Matrix population models a Population growth rates (λ, [95% CI]) are plotted for season- and density-specific matrix population models that were parameterised with the estimates from the MSCMR-models in grey. In blue and green, λ estimates from matrix models with the same survival and breeding values are shown, but the probability to breed communally is fixed to 1 (blue) or 0 (green), simulating populations with females using only one of the two tactics. b Sensitivities [95% CI] for the probability to breed solitarily during the breeding season at two different population densities. The Matrix population models were again parameterised with the estimates from the MSCMR-model (see Table S3, SI).
Source publication
![Matrix population models
a Population growth rates (λ, [95% CI]) are...](publication/359895471/figure/fig3/AS:1144233901735946@1649818029890/Matrix-population-models-a-Population-growth-rates-l-95-CI-are-plotted-for-season_Q320.jpg)
Optimal reproductive strategies evolve from the interplay between an individual’s intrinsic state and extrinsic environment, both factors that are rarely fixed over its lifetime. Conditional breeding tactics might be one evolutionary trajectory allowing individuals to maximize fitness. We apply multi-state capture-mark-recapture analysis to a detai...
Citations
... In this system, younger, lighter females are more likely to rear pups communally with other females, while older females often shift to a more successful solitary rearing tactic [61]. The balance of these tactics is also density dependent, with communal breeding being more common under high-density (lower-quality) environmental conditions [62]. ...
In many species, establishing and maintaining a territory is critical to survival and reproduction, and an animal's ability to do so is strongly influenced by the presence and density of competitors. Here we manipulate social conditions to study the alternative reproductive tactics displayed by genetically identical, age-matched laboratory mice competing for territories under ecologically realistic social environmental conditions. We introduced adult males and females of the laboratory mouse strain C57BL/6J into a large, outdoor field enclosure containing defendable resource zones under one of two social conditions. We first created a low-density social environment, such that the number of available territories exceeded the number of males. After males established stable territories, we introduced a pulse of intruder males and observed the resulting defensive and invasive tactics employed. In response to this change in social environment, males with large territories invested more in patrolling but were less effective at excluding intruder males as compared with males with small territories. Intruding males failed to establish territories and displayed an alternative tactic featuring greater exploration as compared with genetically identical territorial males. Alternative tactics did not lead to equal reproductive success—males that acquired territories experienced greater survival and had greater access to females.
... Female house mice live in family-based territorial social groups and facultatively raise offspring either in solitary nests or communally with familiar partners (most usually in pairs) that share the same nest sites 30,39 . When both opportunities are available, choice appears to be condition-and density-dependent, with younger females choosing communal rearing most frequently while communal rearing increases at high density 40,41 . Improved survival of litters appears to be the main benefit of communal compared to solitary rearing, due to the vulnerability of newborn pups to infanticide from other conspecifics, particularly when mothers are absent from the nest 32,36,[42][43][44][45] . ...
... Improved survival of litters appears to be the main benefit of communal compared to solitary rearing, due to the vulnerability of newborn pups to infanticide from other conspecifics, particularly when mothers are absent from the nest 32,36,[42][43][44][45] . Older and more experienced females can rear more pups per surviving litter when rearing solitarily compared to females breeding communally, but most females in a high-density free-living house mouse population were only able to rear any surviving offspring by cooperative communal rearing 40,41 . Relatives are strongly preferred as nest partners, discriminated through similarity of odours 46,47 . ...
... Only a small proportion of females were able to rear offspring successfully on their own. Although these females reared more pups per surviving litter than those rearing pups communally, these mothers were older, larger and more experienced 40,41 . If other females did attempt to raise offspring alone, all pups were lost before researchers could detect them in fortnightly nest box checks. ...
Breeding females can cooperate by rearing their offspring communally, sharing synergistic benefits of offspring care but risking exploitation by partners. In lactating mammals, communal rearing occurs mostly among close relatives. Inclusive fitness theory predicts enhanced cooperation between related partners and greater willingness to compensate for any partner under-investment, while females are less likely to bias investment towards own offspring. We use a dual isotopic tracer approach to track individual milk allocation when familiar pairs of sisters or unrelated house mice reared offspring communally. Closely related pairs show lower energy demand and pups experience better access to non-maternal milk. Lactational investment is more skewed between sister partners but females pay greater energetic costs per own offspring reared with an unrelated partner. The choice of close kin as cooperative partners is strongly favoured by these direct as well as indirect benefits, providing a driver to maintain female kin groups for communal breeding.
... This long-term study has revealed fundamental knowledge about the reproductive and social lives of mice, especially females (König and Lindholm, 2012). For example, female mice often choose to nest (and nurse) cooperatively when populations are at high densities, allowing for females to reproduce even under suboptimal conditions (Auclair et al., 2014;Ferrari et al., 2022;Harrison et al., 2018). Similarly, Raulo and colleagues (2021) studied the social structure of wild wood mice (Apodemus sylvaticus) using radio frequency identification (RFID) technology to investigate the composition of the gut microbiome across social networks. ...
Social experiences are strongly associated with individuals' health, aging, and survival in many mammalian taxa, including humans. Despite their role as models of many other physiological and developmental bases of health and aging, biomedical model organisms (particularly lab mice) remain an underutilized tool in resolving outstanding questions regarding social determinants of health and aging, including causality, context-dependence, reversibility, and effective interventions. This status is largely due to the constraints of standard laboratory conditions on animals' social lives. Even when kept in social housing, lab animals rarely experience social and physical environments that approach the richness, variability, and complexity they have evolved to navigate and benefit from. Here we argue that studying biomedical model organisms outside under complex, semi-natural social environments ("re-wilding") allows researchers to capture the methodological benefits of both field studies of wild animals and laboratory studies of model organisms. We review recent efforts to re-wild mice and highlight discoveries that have only been made possible by researchers studying mice under complex, manipulable social environments.
... Because female mice can alternate between solitary and communal breeding during their lifetime, breeding tactics in female mice are believed to be phenotypically plastic rather than solely genetically controlled. 23,26 However, even between congeneric mouse species, there is significant variation in breeding strategies. 27 For example, Mus musculus is considered polygynous or promiscuous while Mus spicilegus is monogamous, suggesting that there may be some level of genetic control of breeding phenotypes and social group behavior. ...
Reproductive tactics can profoundly influence population reproductive success, but paradoxically, breeding strategy and female reproductive care often vary across a population. The causes and fitness impacts of this variation are not well understood. Using breeding records from the Collaborative Cross mouse population, we evaluate the effects of breeding configuration on reproductive output. Overall, we find that communal breeding in trios leads to higher output and that both trio-breeding and overlapping litters are associated with increased neonatal survival. However, we find significant strain-level variation in optimal breeding strategy and show that the tradeoff between strategies is weakly heritable. We further find that strain reproductive condition influences the ability to support multiple litters and alters the related evolutionary tradeoffs of communal breeding. Together, these findings underscore the role of genetics in regulating alternative reproductive tactics in house mice and emphasize the need to adopt animal husbandry practices tailored to strain backgrounds.
The evolution of sexual reproduction has perplexed biologists for decades. The earliest organisms on Earth could replicate by themselves, so why do almost all multicellular species combine their genetic material with other individuals to reproduce? After all, asexual reproduction was very successful for well over a billion years. It remains the only mode of reproduction in all of today’s bacteria and is used by many multicellular organisms at certain times in their lifecycle. Sex is costly. It is characterized by increased time and energy at the cellular and organismal levels, may result in injury or even death, and exposes individuals to predators and parasites. Conversely, it can repair damaged stretches of DNA and create the variability necessary for natural selection. Furthermore, assuming that there is some benefit to reproducing sexually, why are sex partners so different? Given that the objective of both individuals is to optimize the production of high-quality progeny, one would expect all members of a species to be similar. Instead, the two types of individuals we denote as biological males and females often exhibit an array of anatomical and behavioural differences that may influence their approach to sexual encounters. Interactions between the two can be co-operative, but their unique strategies often reveal an underlying conflict. This book explores the possible reasons why sex evolved, examines how the differences between males and females arose, and discusses how those differences affect their reproductive strategies.
The regulation of populations through density dependence (DD) has long been a central tenet of studies of ecological systems. As an important factor in regulating populations, DD is also crucial for understanding risks to populations from stressors, including its incorporation in population models applied for this purpose. However, studying density‐dependent regulation is challenging because it can occur through various mechanisms, and their identification in the field, as well as the quantification of the consequences on individuals and populations, can be difficult. We conducted a targeted literature review specifically focusing on empirical laboratory or field studies addressing negative DD in freshwater fish and small rodent populations, two vertebrate groups considered in pesticide ecological risk assessment (ERA). We found that the most commonly recognized causes of negative DD were food (63% of 19 reviewed fish studies, 40% of 25 mammal studies) or space limitations (32% of mammal studies). In addition, trophic interactions were reported as causes of population regulation, with predation shaping mostly small mammal populations (36% of the mammal studies) and cannibalism impacting freshwater fish (26%). In the case of freshwater fish, 63% of the studies were experimental (i.e., with a length of weeks or months). They generally focused on the individual‐level causes and effects of DD, and had a short duration. Moreover, DD affected mostly juvenile growth and survival of fish (68%). On the other hand, studies on small mammals were mainly based on time series analyzing field population properties over longer timespans (68%). DD primarily affected survival in sub‐adult and adult mammal stages and, to a lesser extent, reproduction (60% vs. 36%). Furthermore, delayed DD was often observed (56%). We conclude by making suggestions on future research paths, providing recommendations for including DD in population models developed for ERA, and making the best use of the available data.
Chemical communication by females remains poorly understood, with most attention focused on female advertisement of sexual receptivity to males or mother-offspring communication. However, in social species, scents are likely to be important for mediating competition and cooperation between females determining individual reproductive success. Here, we explore chemical signaling by female laboratory rats (Rattus norvegicus) to test i) whether females target their deployment of scent information differentially according to their sexual receptivity and the genetic identity of both female and male conspecifics signaling in the local environment and ii) whether females are attracted to gain the same or different information from female scents compared to males. Consistent with targeting of scent information to colony members of similar genetic background, female rats increased scent marking in response to scents from females of the same strain. Females also suppressed scent marking in response to male scent from a genetically foreign strain while sexually receptive. Proteomic analysis of female scent deposits revealed a complex protein profile, contributed from several sources but dominated by clitoral gland secretion. In particular, female scent marks contained a series of clitoral-derived hydrolases and proteolytically truncated major urinary proteins (MUPs). Manipulated blends of clitoral secretion and urine from estrus females were strongly attractive to both sexes, while voided urine alone stimulated no interest. Our study reveals that information about female receptive status is shared between females as well as with males, while clitoral secretions containing a complex set of truncated MUPs and other proteins play a key role in female communication.
Genealogical relationships are fundamental components of genetic studies. However, it is often challenging to infer correct and complete pedigrees even when genome‐wide information is available. For example, inbreeding can obscure genetic differences between individuals, making it difficult to even distinguish first‐degree relatives such as parent‐offspring from full siblings. Similarly, genotyping errors can interfere with the detection of genetic similarity between parents and their offspring. Inbreeding is common in natural, domesticated, and experimental populations and genotyping of these populations often has more errors than in human datasets, so efficient methods for building pedigrees under these conditions are necessary. Here, we present a new method for parent‐offspring inference in inbred pedigrees called SPORE (Specific Parent‐Offspring Relationship Estimation). SPORE is vastly superior to existing pedigree‐inference methods at detecting parent‐offspring relationships, in particular when inbreeding is high or in the presence of genotyping errors, or both. SPORE therefore fills an important void in the arsenal of pedigree inference tools.
