Latest Articles
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Section: Ecology ; Topics: Ecology, Evolution, Psychological and cognitive sciences
Bayesian reinforcement learning models reveal how great-tailed grackles improve their behavioral flexibility in serial reversal learning experiments
Lukas, Dieter;
McCune, Kelsey;
Blaisdell, Aaron;
Johnson-Ulrich, Zoe;
MacPherson, Maggie;
Seitz, Benjamin;
Sevchik, August;
Logan, Corina
10.24072/pcjournal.456 - Peer Community Journal, Volume 4 (2024), article no. e88.
Get full text PDFEnvironments can change suddenly and unpredictably and animals might benefit from being able to flexibly adapt their behavior through learning new associations. Serial (repeated) reversal learning experiments have long been used to investigate differences in behavioral flexibility among individuals and species. In these experiments, individuals initially learn that a reward is associated with a specific cue before the reward is reversed back and forth between cues, forcing individuals to reverse their learned associations. Cues are reliably associated with a reward, but the association between the reward and the cue frequently changes. Here, we apply and expand newly developed Bayesian reinforcement learning models to gain additional insights into how individuals might dynamically modulate their behavioral flexibility if they experience serial reversals. We derive mathematical predictions that, during serial reversal learning experiments, individuals will gain the most rewards if they 1) increase their *rate of updating associations* between cues and the reward to quickly change to a new option after a reversal, and 2) decrease their *sensitivity* to their learned association to explore the alternative option after a reversal. We reanalyzed reversal learning data from 19 wild-caught great-tailed grackles (Quiscalus mexicanus), eight of whom participated in serial reversal learning experiment, and found that these predictions were supported. Their estimated association-updating rate was more than twice as high at the end of the serial reversal learning experiment than at the beginning, and their estimated sensitivities to their learned associations declined by about a third. The changes in behavioral flexibility that grackles showed in their experience of the serial reversals also influenced their behavior in a subsequent experiment, where individuals with more extreme rates or sensitivities solved more options on a multi-option puzzle box. Our findings offer new insights into how individuals react to uncertainty and changes in their environment, in particular, showing how they can modulate their behavioral flexibility in response to their past experiences.
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Section: Ecology ; Topics: Ecology
Flexible reproductive seasonality in Africa-dwelling papionins is associated with low environmental productivity and high climatic unpredictability
Dezeure, Jules;
Dagorrette, Julie;
Burtschell, Lugdiwine;
Chowdhury, Shahrina;
Lukas, Dieter;
Swedell, Larissa;
Huchard, Elise
10.24072/pcjournal.464 - Peer Community Journal, Volume 4 (2024), article no. XX.
Get full text PDFAt a time when seasonal cycles are increasingly disrupted, the ecology and evolution of reproductive seasonality in tropical vertebrates remains poorly understood. In order to predict how changes in seasonality might affect these animals, it is important to understand which aspects of their diverse patterns of reproductive phenology are linked to either the equally diverse patterns of rainfall seasonality (within-year variations) or instead the marked climatic unpredictability (year-to-year variations) occurring across the intertropical belt. Here, we gather birth and climatic seasonality data from 21 populations of 11 Africa-dwelling primate species from the papionin tribe, occupying a wide range of environments, including equatorial, tropical, temperate and arid climates. We investigate (1) the environmental variations that influence the intensity of reproductive seasonality, and (2) the reproductive stage that is synchronized with increased resource availability. Our results demonstrate wide variation in the intensity of birth seasonality between and within species. Across multiple measures of climatic variation, we found rainfall unpredictability to be the only clear predictor of the intensity of reproductive seasonality across populations, i.e., greater year-to-year variation in the amount of rainfall was associated with lower to no reproductive seasonality. Finally, we identified diverse patterns of reproductive phenology, with the most seasonal breeders generally aligning lactation with the peak in resource availability while other populations show more diverse patterns, where conception, lactation or weaning can all be synchronized with maximal food availability. This study sheds new light on the extent and ecological drivers of flexible reproductive phenology in long-lived tropical mammals, and may even contribute to our understanding of why humans give birth year-round.
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Section: Mathematical & Computational Biology ; Topics: Ecology, Applied mathematics
Impact of a block structure on the Lotka-Volterra model
10.24072/pcjournal.460 - Peer Community Journal, Volume 4 (2024), article no. e86.
Get full text PDFThe Lotka-Volterra (LV) model is a simple, robust, and versatile model used to describe large interacting systems such as food webs or microbiomes. The model consists of n coupled differential equations linking the abundances of n different species. We consider a large random interaction matrix with independent entries and a block variance profile. The ith diagonal block represents the intra-community interaction in community i, while the off-diagonal blocks represent the inter-community interactions. The variance remains constant within each block, but may vary across blocks. We investigate the important case of two communities of interacting species, study how interactions affect their respective equilibrium. We also describe equilibrium with feasibility (i.e., whether there exists an equilibrium with all species at non-zero abundances) and the existence of an attrition phenomenon (some species may vanish) within each community. Information about the general case of b communities (b > 2) is provided in the appendix
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Section: Animal Science ; Topics: Agricultural sciences
Diversity of performance patterns in dairy goats: multi-scale analysis of the lactation curves of milk yield, body condition score and body weight
10.24072/pcjournal.449 - Peer Community Journal, Volume 4 (2024), article no. e85.
Get full text PDFIn the dairy goat sector, reduced longevity is a key issue leading to higher replacement rates in the herd and a poor dilution of doe-rearing costs. There is a need to better understand the determinants of lifetime performance. Thus, the general objective of this work was to analyze the phenotypic variability of lifetime trajectories (milk yield (MY), body weight (BW) and body condition score (BCS)) through a 3-step approach: (1) characterize individual phenotypic lactation curves, (2) explore the associations between MY, BW and BCS curves at the lactation scale and (3) assess the diversity of phenotypic curves over successive lactations. Routine data from two experimental farms: Le Pradel (Dataset 1, Ardeche department, France) and MoSAR experimental farm (Dataset 2, Yvelines department, France) were used. Dataset 1 included 793 Alpine goats from 1996 to 2020. Dataset 2 included 339 Alpine and 310 Saanen goats from 2006 to 2022. Weekly MY records (Dataset 1) and daily MY records (Dataset 2) were fitted using a lactation model with explicit representation of perturbations. Monthly BW records (Dataset 1) and BCS records (Dataset 1&2) were fitted using the Grossman multiphasic model. Daily BW records (Dataset 2) were fitted using a weight model. Each individual lactation curve modeled for MY, BW and BCS was thus summarized by synthetic indicators of level and dynamics. Principal component analysis was performed on the MY, BW and BCS indicators separately, and clusters of phenotypic curves identified. At the lactation scale, associations between MY, BW and BCS clusters were evaluated by contingency tables with a chi-square test. Lifetime-scale bar plots were used to display cluster changes throughout parities. For MY curves, 4 and 3 clusters were found for primiparous and multiparous goats respectively. For BW, lumbar and sternal BCS curves, 3 clusters were found for all parities. At the lactation scale, no major association was found among phenotypic curves suggesting a diversity of energy partitioning strategies between life functions. At the lifetime scale, change among clusters occurred primarily between first and second lactation, whereas a pattern of stable cluster membership appeared for multiparous goats. Further analyses are needed to include reproductive performance in analyzing lifetime performance clusters, to better identify clusters or combinations of clusters at risk for culling.
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