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After the breeding season, territorial adult Black-crested Titmouse (Baeolophus atricristatus) and residing juveniles form social groups that may persist until the following spring. Under the prolonged brood care hypothesis, one would expect these juveniles to be retained offspring with delayed dispersal of the breeding pair. To test if Black-crested Titmouse juveniles that reside in post-breeding territories are offspring of the territorial adult male, we performed microsatellite-based paternity analyses of 6 juvenile-adult male social dyads on 6 different territories. None of the juveniles were offspring of the adult male with which it shared a territory. We discuss several possible evolutionary explanations for this result. Received 13 August 2021. Accepted 14 December 2021. Key words: delayed dispersal, genotyping. microsatellites, non-kin, parentage, paternity. (Spanish)--Despues de la estacion reproductiva. los adultos territoriales del carbonero Baeolophus atricristatus y juveniles residentes forman grupos sociales que pucden persistir hasta la siguientc primavera. Segiin la hipotesis del cuidado prolongado de la nidada. podria esperarse que esos juveniles fueran descendencia retenida con dispersion retrasada de la pareja reproductiva. Para somcter a prueba si estos carboneros juveniles que residen en territorios posreproductivos son descendientes del macho adulto territorial, llcvamos a cabo un analisis de paternidad basado en microsatelites de 6 diadas de juveniles y machos adultos en 6 difcrentes territorios. Ninguno de los juveniles rue descendiente del macho adulto con el cual compartian territorio. Discutimos varias posiblcs explicaciones evolutivas para este resultado. Palabras clave: dispersion retrasada. genotipos, microsatelites, no-parcntesco, parental, paternidad., In multiple bird species, sexually mature individuals stay in their natal territory and form social family groups (e.g., Brown 1987, Emlen 1995, Koenig and Dickinson 2016). This behavior is widespread [...]

In humans, gut microbiome (GM) differences are often correlated with, and sometimes causally implicated in, ageing. However, it is unclear how these findings translate in wild animal populations. Studies that investigate how GM dynamics change within individuals, and with declines in physiological condition, are needed to fully understand links between chronological age, senescence and the GM, but have rarely been done. Here, we use longitudinal data collected from a closed population of Seychelles warblers (Acrocephalus sechellensis) to investigate how bacterial GM alpha diversity, composition and stability are associated with host senescence. We hypothesised that GM diversity and composition will differ, and become more variable, in older adults, particularly in the terminal year prior to death, as the GM becomes increasingly dysregulated due to senescence. However, GM alpha diversity and composition remained largely invariable with respect to adult age and did not differ in an individual's terminal year. Furthermore, there was no evidence that the GM became more heterogenous in senescent age groups (individuals older than 6 years), or in the terminal year. Instead, environmental variables such as season, territory quality and time of day, were the strongest predictors of GM variation in adult Seychelles warblers. These results contrast with studies on humans, captive animal populations and some (but not all) studies on non‐human primates, suggesting that GM deterioration may not be a universal hallmark of senescence in wild animal species. Further work is needed to disentangle the factors driving variation in GM‐senescence relationships across different host taxa. [ABSTRACT FROM AUTHOR]

Investigating fundamental processes in biology requires the ability to ground broad questions in species‐specific natural history. This is particularly true in the study of behavior because an organism's experience of the environment will influence the expression of behavior and the opportunity for selection. Here, we provide a review of the natural history and behavior of burying beetles of the genus Nicrophorus to provide the groundwork for comparative work that showcases their remarkable behavioral and ecological diversity. Burying beetles have long fascinated scientists because of their well‐developed parenting behavior, exhibiting extended post‐hatching care of offspring that varies extensively within and across taxa. Despite the burgeoning success of burying beetles as a model system for the study of behavioral evolution, there has not been a review of their behavior, ecology, and evolution in over 25 years. To address this gap, we leverage a developing community of researchers who have contributed to a detailed knowledge of burying beetles to highlight the utility of Nicrophorus for investigating the causes and consequences of social and behavioral evolution. [ABSTRACT FROM AUTHOR]

Parents confront multiple aspects of offspring demands and need to coordinate different parental care tasks. Biparental care is considered to evolve under circumstances where one parent is not competent for all tasks and cannot efficiently raise offspring. However, this hypothesis is difficult to test, as uniparental and biparental care rarely coexist. Chinese penduline tits (Remiz consobrinus) provide such a system where both parental care types occur. Here, we experimentally investigated whether parents in biparental nests are less capable of caring than parents in uniparental nests. We monitored parenting efforts at (1) naturally uniparental and biparental nests and (2) biparental nests before and during the temporary removal of a parent. Given the relatively small sample sizes, we have employed various statistical analyses confirming the robustness of our results. We found that total feeding frequency and brooding duration were similar for natural uniparental and biparental nests. Feeding frequency, but not brooding duration, contributed significantly to nestling mass. In line with this, a temporary parental removal revealed that the remaining parents at biparental nests fully compensated for the partner's feeding absence but not for brooding duration. This reflects that the manipulated parents are confronted with a trade‐off between feeding and brooding and were selected to invest in the more influential one. However, such a trade‐off may not occur in parents of natural uniparental care nests. The different capabilities of a parent independently coordinating feeding and brooding tasks suggest that parents from biparental and uniparental nests were exposed to different resource conditions, thereby foraging efficiency may differ between care types. [ABSTRACT FROM AUTHOR]

Cooperative breeding occurs when helpers provide alloparental care to the offspring of a breeding pair. One hypothesis of why helping occurs is that helpers gain valuable skills that may increase their own future reproductive success. However, research typically focuses on the effect of helping on short-term measures of reproductive success. Fewer studies have considered how helping affects long-term fitness measures. Here, we analyze how helping experience affects key breeding and fitness-related parameters in the Seychelles warbler (Acrocephalus sechellensis). Importantly, we control for females that have cobred (reproduced as a subordinate by laying an egg within a territory in which they are not a dominant breeder), as they already have experience with direct reproduction. Helping experience had no significant association with any of the metrics considered, except that helpers had an older age at first dominance. Accounting for helping experience, females that had cobred produced more adult offspring (≥1 year) after acquiring dominance and had a higher lifetime reproductive success (LRS) than females that had never cobred. Our results suggest that, in the Seychelles warbler, helping experience alone does not increase the fitness of helpers in any of the metrics considered, and highlights the importance of separating the effects of helping from cobreeding. Our findings also emphasize the importance of analyzing the effect of helping at various life-history stages, as higher short-term fitness may not translate to an overall increase in LRS. [ABSTRACT FROM AUTHOR]