Biology subjects

Mwanguhya, F.

Publications and source records attributed to Mwanguhya, F..

8 recordsLinked to original sources

bioRxiv2025

Collective Self-Assessment in Banded Mongoose Intergroup Contests

Contests over resources are widespread in nature. To optimize outcomes, animals assess fighting abilities, deciding to escalate conflicts based on their own strength (self-assessment) or comparing their own strength with that of their rival (mutual assessment). While most research focuses on one-on-one (dyadic) contests, the assessment strategies employed by groups remain poorly understood. Mutual assessment is frequently assumed, as more information is thought to improve decision-making; however, this assumption has rarely been tested. Here we used a dataset spanning 23 years and 641 intergroup contests in a banded mongoose (Mungos mungo) population in Queen Elizabeth National Park, Uganda. Our results support a model of self-assessment: groups with many males tend to escalate conflicts regardless of the rival groups strength, thus contrasting the commonly held assumption that decisions during intergroup contests are made by mutual assessment. We suggest that assessing rival group strength during conflict could be disproportionately costly, compared with assessing own group strength, which can be done over longer time periods and is easier to obtain. Greater understanding of these dynamics can shed light on the drivers and escalation patterns of intergroup conflict across social species, including humans. Lay SummaryWhen two rival groups come together, what determines whether or not they fight? We found support for the hypothesis that banded mongoose groups escalate into physical fights based upon an estimation of their own groups strength, which we term collective self-assessment. We did not find evidence for a commonly held notion that groups compare their own groups strength with their rivals. Distinguishing between assessment strategies is intensively researched in contests between individuals but has rarely been applied to intergroup conflict. Here we applied the successful "assessment strategy framework" to group conflict, analyzing over 20 years of data from over 600 intergroup interactions. We suggest that collective self-assessment is employed because it is faster than mutual assessment, which offers an advantage in conflicts where time is of the essence.

animal behavior and cognition↗

bioRxiv2025

A landscape of intergroup conflict shapes den site choice in banded mongooses

BackgroundFor many social animals, intergroup conflict has major impacts on fitness and should therefore influence how groups navigate their environment. Yet most studies of group movement focus on the behaviour of single groups, usually foraging groups studied in isolation of all others. In many systems rival groups present both threats and opportunities, contributing to a landscape of intergroup conflict. This landscape could have a profound impact on group movement. MethodsHere we test how the potential for intergroup conflict influences movement decisions of wild cooperatively breeding banded mongooses, using 14 years of behavioural and GPS data. In this species, encounters between groups can present both risks (e.g. injury/mortality) and opportunities (e.g., extragroup mating). We expected that, to minimise risks and maximise rewards, the motivation to engage in conflict would depend on the groups state. Such that vulnerable groups (those that were babysitting young offspring) would select den sites closer to the core of their territory than groups without young offspring. ResultsWe found support for this pattern; non-babysitting groups were unusually risk prone choosing den locations in areas of frequent use by outgroups. During times of heightened recent conflict even choosing to den closer to the core of their rivals territory than their own. ConclusionsThese results suggest that groups of banded mongooses choose den sites that reflect not only the risks but also the potential rewards of defensive or competitive claims on space. Rival groups thus form an integral part of the social landscape shaping patterns of collective movement.

animal behavior and cognition↗

bioRxiv2024

Banded mongooses discriminate relatedness and MHC diversity in unfamiliar conspecifics

Olfactory cues are critical in mammalian social communication, conveying fitness-relevant information such as relatedness, genetic quality, and compatibility. Recognizing kin through scent can help avoid inbreeding depression and guide nepotistic behaviors, enhancing both direct and indirect fitness. While many species use familiarity to identify relatives, others rely on phenotype matching, where animals assess genetic similarity by comparing their own genetically determined odor with that of others. In banded mongooses, synchronized breeding disrupts familiarity cues, increasing reliance on alternative mechanisms for kin discrimination and mate selection. We tested whether banded mongooses use odors to assess genetic diversity and relatedness based on (1) major histocompatibility complex (MHC) genotypes and (2) neutral microsatellite loci that reflect genetic diversity and relatedness. We found that individuals respond differently to odors from unfamiliar individuals based on MHC diversity and genetic relatedness. Specifically, individuals show more interest in less MHC diverse and less related unfamiliar conspecifics, suggesting odor cues are used to evaluate threat level of intruders or competitors. Genetic diversity had no impact on responses to odors and was not significantly associated with MHC diversity, implying that responses to MHC diversity did not result from an underlying correlation with over-all genetic diversity. We also found no effect of MHC similarity, which might be caused by the limited sample size for this analysis. Our findings show that MHC diversity might signal the genetic quality of individuals, but regions of the genome other than MHC may be used to assess relatedness. These findings provide the basis for future research on the involvement of the MHC and other genes in social communication in species where phenotype matching is likely to be advantageous.

animal behavior and cognition↗

bioRxiv2024

Sex-dependent influence of major histocompatibility complex diversity on fitness in a social mammal

Parasite infections affect males and females differently across a wide range of species, often due to differences in immune responses. Generally, females tend to have stronger immune defenses and lower parasite loads than males. The major histocompatibility complex (MHC) plays a crucial role in the adaptive immune response, and extensive research has explored how variation in this region influences infection and fitness outcomes. However, studies of sex-specific relationships between MHC variation and infection are scarce, perhaps because MHC genes are located on the autosomes, which are shared by both sexes. Here, we provide evidence of sexually antagonistic selection in a wild, group-living mammal--the banded mongoose. Using genetic and life history data collected from over 300 individuals across 25 years, we found that particularly MHC class I (MHC-I) but also MHC class II (MHC-II) diversity influence lifetime reproductive success differently in males and females. Specifically, higher MHC diversity is linked to increased fitness in males but decreased fitness in females. Furthermore, MHC diversity did not differ between the sexes, indicating an unresolved genetic sexual conflict. Our findings demonstrate that sexually antagonistic selection acts on the MHC and may operate across both MHC classes but differently. This study contributes to the growing body of evidence that sex is a significant factor in shaping host immunity and fitness.

evolutionary biology↗

bioRxiv2024

Characterization of both major histocompatibility complex classes in a wild social mammal: the banded mongoose

The major histocompatibility complexs (MHC) role in the vertebrate adaptive immune response and its exceptional polymorphism make it a key target for studying adaptive gene evolution. However, previous studies on carnivore MHC have mostly focused on populations which experienced a severe bottleneck or are of general conservation concern. Hence, sample sizes are often small and generalizations about MHC diversity are unreliable. Furthermore, studies often focus on one MHC class and do not cover the whole peptide binding groove of the MHC molecule. Here, we characterize MHC class I (MHC-I) exon 2 and 3, encoding both the 1- and 2-domain of the MHC-I molecule, as well as MHC-II DRB exon 2 for a large sample (N = 282-485) of a wild mammal of least conservation concern, the banded mongoose. We found that MHC-I generally showed higher allelic diversity and polymorphism compared to MHC-II, which is in line with findings in humans that show higher diversifying selection acting on MHC-I. However, MHC-I exon 3 showed the lowest diversity, possibly due to its different role in generating the peptide binding groove of the class I molecule compared to exon 2. Moreover, we found selection to act more strongly on MHC-I exon 2 (domain 1) than exon 3 (domain 2). Despite frequent inbreeding, phylogenetic comparative analysis showed banded mongooses to have MHC diversity levels comparable with other carnivores of least concern. Phylogenetic analysis indicated a longer evolutionary trajectory for MHC-II compared to MHC-I as well as species-specific gene duplication of nonclassical sequences of MHC-I clustering with classical sequences. Trans-species polymorphism was detected for nonclassical MHC-I sequences suggesting homology or convergent evolution for these genes. Our study is the first to characterize both MHC classes of a social, wild carnivore using a high throughput sequencing approach with a large sample size and thereby provides the basis for further investigation of MHC structure and function within the banded mongoose and other carnivores.

genetics↗

bioRxiv2024

Fitness incentives to male fighters undermine fighting performance in intergroup contests

In humans and other animal societies, groups engage in intergroup conflicts over resources. The success of groups in these conflicts depends on individual contributions to collective fighting, yet individuals may have personal fitness incentives to defect rather than fight, which could undermine group performance. Here we test the hypothesis that personal fitness incentives affect intergroup conflict success in wild banded mongooses (Mungos mungo). In this species, intergroup fights are sometimes initiated by estrous females, who gain outgroup matings while their male group-mates contribute most of the fighting effort. We found that group fighting success was highest when a groups females were in estrus, suggesting that, although females may initiate fights, their male group-mates seem motivated to chase away rival groups to defend their paternity. Surprisingly, we found that groups that won fights conceded more paternity to their rivals than groups that lost. In other words, behavioral "wins" did not always result in fitness "wins". Younger males were more successful at attaining paternity between groups compared to within their own groups, suggesting that they may forego intergroup fighting to focus on intergroup mating. Overall, our results suggest that personal fitness incentives--here, in the form of paternity--vary widely among group members and can undermine rather than promote collective fighting performance. Such conflicts of interest are likely inherent in group combat and can contribute to variation in the frequency and costliness of intergroup violence.

animal behavior and cognition↗

bioRxiv2024

Strategic use of male alternative reproductive tactics in cooperatively breeding banded mongoose groups

Alternative reproductive tactics (ARTs) allow smaller or less competitive individuals to reproduce by avoiding direct fights through sneaky strategies. Within cooperatively breeding groups ARTs are rarely reported, potentially due to difficulties observing male reproductive behaviour in the wild, or reproductive suppression by fellow group members. In societies where all mating opportunities cannot be monopolised by one male, young males could use sneaky tactics as a stepping-stone to gain limited reproductive success while they grow in resource holding potential (RHP). Using 20 years of pedigree, weight, group demography, and behavioural data, we investigated the use of sneaky pesterer ARTs in wild banded mongooses. Instead of a stepping stone, pestering tactics were typically a rare back-up used by males displaced from mate guarding tactics by higher RHP rivals. Additionally, pesterers have lower siring success compared to mate guards, despite similar weight loss costs, which may explain why most males settle for reproductive inactivity rather than use pestering tactics. However, pestering allows younger males to gain access to older, higher fecundity females in the group and may even facilitate inbreeding avoidance. Overall, ARTs provide a viable option for reproductive fitness for some males that lose out on reproductive positions in highly male-skewed groups.

animal behavior and cognition↗

bioRxiv2024

Reproductive restraint to avoid the costs of reproductive conflict in a cooperatively breeding mammal

The costs of reproductive conflict can be an important factor shaping the evolution of life histories in animal societies. These costs may change as individuals age and grow, and with within-group competition. Social costs of reproductive conflict have been invoked to explain why females might gain from delaying maturity or ceasing reproduction midway through life, but not in males. Here we analyze more than 20 years of data to understand how individual male banded mongooses adjust their reproductive activity in response to the costs of reproductive conflict. In banded mongooses groups multiple female breeders enter oestrus synchronously and males compete to mate guard the females. The oldest and heaviest males in the group gained the greatest share of paternity, while younger and lighter males obtained little or no paternity. Those lighter males that are reproductively active paid disproportionate survival costs. Our results suggest that by delaying or suppressing reproduction early in life, males may reduce their mortality. Males may also avoid inflicting costs on their male kin by queuing. These results from an egalitarian cooperative breeding mammal may provide a rare example of voluntary reproductive restraint, although we cannot discount reproductive suppression by rival males.

animal behavior and cognition↗