Research papers by Loreto A. Correa
1. Alternative morphotypes have been reported less frequently in females than in males. An except... more 1. Alternative morphotypes have been reported less frequently in females than in males. An exception to this rule is the gradient of phenotypical masculinization reported in some female mammals, in which feminized and masculinized females represent two opposite ends along this gradient. These phenotypical differences originate during prenatal development as the consequence of maternal effects. Feminized and masculinized females differ in several traits, including morphological, physiological, behavioural and reproductive traits. 2. Differences previously reported in reproductive traits between feminized and masculinized females come mostly from mechanistic studies performed in the laboratory, and not necessarily on social species. As a result, it is unclear to what extent these reported differences between female alternative morphotypes materialize in wild, natural populations. 3. We quantified the effect of female alternative morphotype on female reproductive traits in a natural population of Octodon degus, a highly social rodent. We assessed female alternative morphotype through a continuous gradient of anogenital distance. Thus, feminized females were close to the short end of anogenital distance, while masculinized females were close to the long end of this gradient. We also tested the hypothesis that the social environment interacts with female morphotype to influence female reproductive traits. 4. In female degus, only body weight affected litter size, where heavier females weaned more offspring. Masculinized females delivered male-biased litters and weaned heavier offspring. Lastly, masculinized females gave birth later in the breeding season compared to feminized females. 5. Contrary to previous claims, our findings do not support that masculinized females are less fertile than feminized females. Moreover, masculinized females produced heavier, potentially higher quality offspring compared with feminized females.
Papers by Loreto A. Correa
Austral journal of veterinary sciences, Aug 31, 2023
Abstract: Alternative morphotypes have been reported in males of different taxa. In some mammals ... more Abstract: Alternative morphotypes have been reported in males of different taxa. In some mammals highly masculinized and slightly masculinized males represent two opposite ends along a gradient of phenotypic variation in males. This phenotypical gradient originates during prenatal development. Laboratory studies have documented how highly and slightly masculinized males differ in several traits, including their reproductive success. However, the extent to which these reported differences materialize in natural populations remains unknown. We quantified the impact of male morphotype on male reproductive success in a natural population of Octodon degus, a highly social rodent. We assessed male morphotype through a continuous gradient of anogenital distance. We also tested the hypothesis that the social environment interacts with male morphotype to influence male reproductive success. We found that individual attributes, including masculinization level and age, impacted male reproductive success. Highly masculinized and younger males had greater reproductive success. Additionally, male body weight had a small magnitude but positive effect on male reproductive success. Male reproductive success was not affected by social attributes such as group composition. Thus, the number of males and females within a group did not affect male reproductive success, nor did the average male anogenital distance within a group. Our results support the hypothesis that the prenatal environment can result in long-term effects on individual life history and cause intrasexual phenotypical variation in natural populations. Our findings suggest that male phenotypical masculinization could be an adaptive trait, regardless of the social environment
Physiology & Behavior, 2013
Female phenotypic masculinization is a phenomenon widely described among mammals. In species that... more Female phenotypic masculinization is a phenomenon widely described among mammals. In species that produce litters, female masculinization occurs in utero during late trimester of pregnancy as consequence of the intrauterine position phenomenon (IUP), affecting morphological, physiological and behavioral traits during adulthood. One morphological trait that is affected by IUP is anogenital distance (AGD) that is utilized as proxy of the female phenotypic masculinization. In rodents, IUP have ecological and behavioral effects including aggressiveness, territory marking, activity level, parental care and sociality. In this work, we evaluated how female masculinization (or feminization) affects aggressive behavior and determines social dominance, which in turn could lead to the structuring of social groups through dominance hierarchy formation in degus. We carried out a laboratory study where we established artificial social groups composed of females with the similar and different AGDs, and recorded all social interactions identifying initiator/recipient in dyad relationships and the nature of each interaction. Female aggression varied depending on the degree of females' masculinization, but only in mixed groups (those composed of females with different AGDs) was a hierarchical relationship observed. Furthermore, dominance hierarchies were constructed mostly on the basis of submissive, rather than aggressive interactions. Finally, female behavioral and morphological masculinization was not due to higher plasma testosterone levels, which would indicate that the masculinization of the female phenotype is the consequence of the organizational effects of steroid hormones during ontogeny.
Homophily by morphological and behavioral traits has been described in several species of vertebr... more Homophily by morphological and behavioral traits has been described in several species of vertebrates, but its functional consequences remain poorly studied. Homophily by plurally breeding females may improve direct fitness by enhancing reproductive success. Female mammals may exhibit phenotypical masculinization due to exposure to androgens during early development, a condition that is associated with maternal performance during subsequent breeding. Our goal was to assess whether female composition (in terms of masculinization) of plurally breeding groups influences female fitness in a natural population of degus (Octodon degus). We assessed if plurally breeding female degus assort themselves by anogenital distance (AGD), an accurate measure of masculinization level. We also quantified if homophily by AGD phenotype affects female reproductive success and the reproductive output of the group. Plurally breeding groups typically included similarly masculinized (i.e., long AGD) females...
Permanent changes in group membership may result in detrimental fitness effects on both group res... more Permanent changes in group membership may result in detrimental fitness effects on both group residents and immigrants. Factors associated with this form of social instability are rarely documented. We used a 15-year dataset on degus, a social and short-lived species, to test the hypothesis that physical condition and socioecological factors experienced during breeding are associated with social instability in terms of group individual membership (hypothesis 1). We also tested the hypothesis that these factors represent potential cues for individuals to predict social instability conditions during subsequent breeding (i.e., exhibiting autocorrelation) (hypothesis 2). Social instability in degu group membership was ubiquitous. Social instability increased with increasing ectoparasite load but decreased with increasing food abundance, increasing degu density, increasing mean minimum temperature, and increasing number of female group members. Of these conditions, degu density during wi...
Behaviour
We report the results of a 6-year study of social (number of adult males/females, relatedness of ... more We report the results of a 6-year study of social (number of adult males/females, relatedness of females, communal litter size) and ecological (mean/CV of food abundance, soil hardness, burrow openings) factors influencing the direct fitness of plurally breeding degu (Octodon degus) females. The best fit models for per capita offspring weaned and standardized variance in direct fitness (within-group variation) included the number of adult males per group. Per capita number of offspring weaned decreased and standardized variance in direct fitness increased with increasing number of adult males per group. Thus, females experience a cost associated with males that is not shared equally. Standardize variance in direct fitness decreased with increasing communal litter size. All other factors were not significant predictors of direct fitness variation. Our study suggests that plural breeding may not be as egalitarian as previously thought. Consequences of plural breeding may be influenced...
General and comparative endocrinology, Jan 12, 2018
The Common Degu (Octodon degus) is a small rodent endemic to central Chile. It has become an impo... more The Common Degu (Octodon degus) is a small rodent endemic to central Chile. It has become an important model for comparative vertebrate endocrinology because of several uncommon life-history features - it is diurnal, shows a high degree of sociality, practices plural breeding with multiple females sharing natal burrows, practices communal parental care, and can easily be studied in the laboratory and the field. Many studies have exploited these features to make contributions to comparative endocrinology. This review summarizes contributions in four major areas. First are studies on degu stress responses, focusing on seasonal changes in glucocorticoid (GC) release, impacts of parental care on offspring GC responses, and fitness consequences of individual variations of GC responses. These studies have helped confirm the ecological relevance of stress responses. Second are studies exploring diurnal circadian rhythms of melatonin and sex steroids. These studies have formed important wor...
Journal of Animal Ecology, 2016
Alternative morphotypes have been reported less frequently in females than in males. An exception... more Alternative morphotypes have been reported less frequently in females than in males. An exception to this rule is the gradient of phenotypical masculinization reported in some female mammals, in which feminized and masculinized females represent two opposite ends along this gradient. These phenotypical differences originate during prenatal development as the consequence of maternal effects. Feminized and masculinized females differ in several traits, including morphological, physiological, behavioural and reproductive traits. Differences previously reported in reproductive traits between feminized and masculinized females come mostly from mechanistic studies performed in the laboratory, and not necessarily on social species. As a result, it is unclear to what extent these reported differences between female alternative morphotypes materialize in wild, natural populations. We quantified the effect of female alternative morphotype on female reproductive traits in a natural population of Octodon degus, a highly social rodent. We assessed female alternative morphotype through a continuous gradient of anogenital distance. Thus, feminized females were close to the short end of anogenital distance, while masculinized females were close to the long end of this gradient. We also tested the hypothesis that the social environment interacts with female morphotype to influence female reproductive traits. In female degus, only body weight affected litter size, where heavier females weaned more offspring. Masculinized females delivered male-biased litters and weaned heavier offspring. Lastly, masculinized females gave birth later in the breeding season compared to feminized females. Contrary to previous claims, our findings do not support that masculinized females are less fertile than feminized females. Moreover, masculinized females produced heavier, potentially higher quality offspring compared with feminized females.
Journal of Animal Ecology, 2016
Group size may influence fitness benefits and costs that emerge from cooperative and competitive ... more Group size may influence fitness benefits and costs that emerge from cooperative and competitive interactions in social species. However, evidence from plural breeding mammals indicates that group size is insufficient to explain variation in direct fitness, implying other attributes of social groups were overlooked. We studied the natural population of a social rodent during 5 years to test the hypothesis that social stability - in terms of group composition - modulates the effects of increasing number of breeding females (a proxy of communal rearing) and males on the number of offspring weaned (sired) and on the number of offspring weaned (sired) surviving to breeding age (two proxies of direct fitness). We quantified the effects of social stability (measured as changes in female or male group members between mating and the onset of lactation) on these fitness measures. We used live trapping, telemetry and DNA markers to determine social and fitness measures. Social stability in degus was variable in terms of the number of changes in group composition across groups. Low stability was mostly due to mortality and emigration of group members. Results supported a modulating role of social stability on the relationship between group size and the number of offspring weaned (sired). Stability in female and male group composition were both modulators of fitness to females and males. The modulatory role of stability was sex specific, where high social stability was often fitness beneficial to the females. Instead, low social stability was fitness enhancing to the males.
Tropical Animal Health and Production, 2012
Naturwissenschaften, 2013
Journal of Ethology, 2009
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2011
Behavioural Processes, 2013
Applied Animal Behaviour Science, 2010
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Research papers by Loreto A. Correa
Papers by Loreto A. Correa