Anogenital distance as a measure of male competitive ability in Rwenzori Angolan colobus

The use of anogenital distance as a non-invasive predictor of seminal quality in captive squirrel monkey (Saimiri collinsi Osgood 1961)

BACKGROUND

Anogenital distance is considered a non-invasive measure to assess the development and functionality of sexual organs in different animal species. Hence, this measurement could potentially be used during the selection of non-human primates for reproductive biotechnology programs. The aim of this study was to assess the correlation between anogenital distance and reproductive parameters in captive Saimiri collinsi.

METHODS

Eight mature S. collinsi males were evaluated. Body weight, reproductive hormone levels, testicular volume, and seminal parameters were determined, and their relationship with anogenital distance measurements was assessed.

RESULTS

Anogenital distance was correlated with seminal volume, sperm motility, vigor, and plasma membrane integrity, but not with body weight, reproductive hormones, and testicular volume.

CONCLUSION

The determination of anogenital distance is a non-invasive method to predict seminal quality. This procedure has the advantage of providing andrologic information without a negative impact on animal welfare.

Maternal effects in mammals: Broadening our understanding of offspring programming

The perinatal period is a sensitive time in mammalian development that can have long-lasting consequences on offspring phenotype via maternal effects. Maternal effects have been most intensively studied with respect to two major conditions: maternal diet and maternal stress. In this review, we shift the focus by discussing five major additional maternal cues and their influence on offspring phenotype: maternal androgen levels, photoperiod (melatonin), microbiome, immune regulation, and milk composition. We present the key findings for each of these topics in mammals, their mechanisms of action, and how they interact with each other and with the maternal influences of diet and stress. We explore their impacts in the contexts of both predictive adaptive responses and the developmental origins of disease, identify knowledge gaps and research opportunities in the field, and place a particular emphasis on the application and consideration of these effects in non-model species and natural ecological systems.

Temporal patterns in the social network of core units in Rwenzori Angolan colobus monkeys: Effects of food availability and interunit dispersal

Multi-level societies are complex, nested social systems where basic social groups (i.e., core units) associate in a hierarchical manner, allowing animals to adjust their group sizes in response to variables such as food availability, predation, or conspecific threat. These pressures fluctuate over time and examining the extent to which this variation affects the clustering of core units into different tiers may be instrumental in understanding the evolution of multi-level societies.The goal of our study was to determine the degree of temporal variability in interunit associations in a multi-level society of Rwenzori Angolan colobus monkey (Colobus angolensis ruwenzorii), and to determine the social and ecological factors that underlie association patterns. The C. a. ruwenzorii multi-level society consists of at least three tiers, with core units clustering into clans that share a home range in a band tier.We performed social network analyses on 21 months of association data from 13 core units (totaling 139 identifiable individuals) at Lake Nabugabo, Uganda. We described the patterns of variation in core-unit associations over time and investigated how changes in rainfall, food availability, and interunit dispersals were correlated with these associations over the short-term (month to month) and long-term (year to year).Although clans were relatively stable, larger-scale changes in association patterns included the formation of an all-male unit and the transfer of one core unit between clans (within the band tier). Seasonally, core units associated significantly more when fruit, their preferred food source, was abundant (i.e., social networks were denser and more clustered) and there was no direct effect of rainfall seasonality or young leaf availability. Male dispersals also occurred more during periods of high fruit availability, suggesting that greater band cohesion allowed males to prospect and transfer between core units. Once males transferred, their previous and new units associated significantly more with one another than with other core units for 1-2 months postdispersal. The dispersal of five males from one core unit to another in a different clan co-occurred with this core unit switching its clan affiliation.By examining temporal shifts in social network structure among core units, this study shows the interconnected roles that food availability and dispersal have in shaping the C. a. ruwenzorii multi-level social system. Our findings highlight how ecological conditions can drive association patterns, impact interunit relationships, and influence social organization.