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opencc-by-4.0Jun 2023View details →

Supplementary material for "Food availability affects parental anti-predator behaviour in red kites"

Abstract Parental investment theory proposes two non-mutually exclusive hypotheses to explain variation in anti-predator behaviour in relation to the age of offspring: the “reproductive value of offspring” hypothesis and the “harm to offspring” hypothesis. The relative importance of the two factors underlying the hypotheses, reproductive value and harm, may change depending on environmental conditions such as food availability. To test the relative importance of the two hypotheses under different food conditions, we conducted a supplementary feeding experiment in red kite (Milvus milvus) breeding pairs and used a live eagle owl (Bubo bubo) as decoy nest predator to trigger anti-predator behaviour. We used time-to-capture in mist nets mounted next to the decoy predator as proxy for mobbing intensity. Under natural food conditions we found a nearly constant mobbing intensity throughout the entire nestling period. However, under food-enhanced conditions mobbing intensity was reduced in parents with young nestlings and increased in parents with old nestlings. These results suggest greater importance of the “reproductive value of offspring” hypothesis in situations of favourable food availability. Moreover, mobbing intensity depended on brood size and weather conditions. The results suggest that parental anti-predator investment increases with the reproductive value of the brood under favourable breeding conditions, but that this pattern is adjusted to the current context, including the vulnerability of the brood and environmental conditions.

opencc-by-4.0Jun 2021View details →

Availability and trends in sports foods available for sale at New Zealand supermarketsy of sports foods globally and in New Zealand supermarkets

Sports foods are specially formulated to help people achieve specific nutritional or sporting performance goals. Anecdotal evidence suggests increasing availability and marketing of such products to consumers, however, very few studies have looked at in-store product availability.  Data for 2013 to 2018 were collected from the Nutritrack database, an online searchable database of all unique packaged foods and beverages sold at four main supermarket chains in New Zealand. Availability of sports foods and on-pack marketing techniques were assessed in 2018 using descriptive analysis, and changes in proportions over time were assessed using Chi-Square analyses. In 2018, the proportion of packaged foods available in major New Zealand supermarkets which were classified as sports foods was 2.1% (n=325), which had increased from 1.8% (n=247) in 2013. Sports foods also appeared in more food groups and subcategories in 2018 compared with 2013 (11 vs. 6 food groups, and 25 vs. 19 subcategories, respectively). The use of on-pack marketing techniques also increased over time, with Nutrient Claims present on 87% of sports foods in 2013 and 98% in 2018. The implications of the increase in product availability and on-pack marketing of sports foods in New Zealand supermarkets warrants consideration from public health, sporting, and consumer sectors. Sports foods are specially formulated to help people achieve specific nutritional or sporting performance goals. Anecdotal evidence suggests increasing availability and marketing of such products to consumers, however, very few studies have looked at in-store product availability.  Data for 2013 to 2018 were collected from the Nutritrack database, an online searchable database of all unique packaged foods and beverages sold at four main supermarket chains in New Zealand. Availability of sports foods and on-pack marketing techniques were assessed in 2018 using descriptive analysis, and changes in proportions over time were assessed using Chi-Square analyses. In 2018, the proportion of packaged foods available in major New Zealand supermarkets which were classified as sports foods was 2.1% (n=325), which had increased from 1.8% (n=247) in 2013. Sports foods also appeared in more food groups and subcategories in 2018 compared with 2013 (11 vs. 6 food groups, and 25 vs. 19 subcategories, respectively). Use of on-pack marketing techniques also increased over time, with Nutrient Claims present on 87% of sports foods in 2013 and 98% in 2018. The implications of the increase in product availability and on-pack marketing of sports foods in New Zealand supermarkets warrants consideration from public health, sporting, and consumer sectors.

Fig. 2 in Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

Fig. 2. Ordination by principal coordinate analysis (PCoA) of the food resource availability for six floodplain lakes along the Upper Paraná River, Paraná-Mato Grosso do Sul. AQI = aquatic insects; OAI = other aquatic invertebrates; OTI = other terrestrial invertebrates; PLA = plants; TRI = terrestrial insects.

Fig.5 in Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

Fig.5. Relationship between the mean of the proportional overlap Index (IS) and the scores of the first PCoA axis of resource availability in isolated floodplain lakes along the upper Paraná River.Values of IS closer to 1 indicates greater diet overlap. The mean IS was calculated based on individuals of 3 (ZÉ = ZÉ Marinho), 7 (Carioca = Car), 4 (TiÃo = Tia), 5 (Genipapo = Gen), 2 (CidÃo = Cid) and 5 species (Canal = Can).AQI = aquatic insects; PLA = plants.

Fig. 1 in Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

Fig. 1. Locations of the lakes on the upper Paraná River floodplain, Brazil: 1, Canal do Meio; 2, Carioca; 3, ZÉ Marinho; 4, CidÃo; 5, Genipapo; 6, TiÃo.

Fig. 4 in Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

Fig. 4. Relationship of the mean the Schoener's Index (O) between pairs of species and the scores of the first PCoA axis of resource availability in isolated floodplain lakes along the upper Paraná River. The mean O was calculated based on 10 (ZÉ = ZÉ Marinho), 28 (Carioca = Car), 6 (TiÃo = Tia), 21 (Genipapo = Gen), 3 (CidÃo = Cid) and 10 (Canal = Can) pairs of species. AQI = aquatic insects; PLA = plants.

Fig. 3 in Trophic relationships in fish assemblages of Neotropical floodplain lakes: selectivity and feeding overlap mediated by food availability

Fig. 3. Relationships between feeding selectivity by fish and the availability of food resources for six floodplain lakes along the Upper Paraná River, ParanáMato Grosso do Sul. Shape of data distribution (envelope effect) was significant.

opencc-zeroJun 2023View details →

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Can regime shifts in reproduction be explained by changing climate and food availability?

Marine populations often show considerable variation in their productivity, including regime shifts. Of special interest are prolonged shifts to low recruitment and low abundance which occur in many fish populations despite reductions in fishing pressure. One of the possible causes for the lack of recovery has been suggested to be the Allee effect (depensation). Nonetheless, both regime shifts and the Allee effect are empirically emerging patterns but provide no explanation about the underlying mechanisms. Environmental forcing, on the other hand, is known to induce population fluctuations and has also been suggested as one of the primary challenges for recovery. Yet, traditional stock-recruitment models used in fisheries management have been time-invariant and considered only density-dependence. In the present study, we build upon recently developed Bayesian change-point models to explore the contribution of food and climate as external drivers in recruitment regime shifts, while accounting for density-dependent mechanisms (compensation and depensation). Food availability is approximated by the copepod community. Temperature is included as a climatic driver. Three demersal fish populations in the Irish Sea are studied: Atlantic cod (Gadus morhua), whiting (Merlangius merlangus), and common sole (Solea solea). We demonstrate that while spawning stock biomass undoubtedly impacts recruitment, abiotic and biotic drivers can have substantial additional impacts, which can explain regime shifts in recruitment dynamics or low recruitment at low population abundances. Our results stress the fact that traditional abundance-based stock-recruitment models are not sufficient to capture variability in fish recruitment.

opencc-by-4.0Jun 2023View details →

Data and code for "Turning tables: food availability shapes dynamic aggressive behaviour among asynchronously hatching siblings in red kites Milvus milvus"

Abstract Aggression represents the backbone of dominance acquisition in several animal societies, where the decision to interact is dictated by its relative cost. Among siblings, such costs are weighted in the light of inclusive fitness, but how this translates to aggression patterns in response to changing external and internal conditions remains unclear. Using a null-model-based approach, we investigate how day-to-day changes in food provisioning affect aggression networks and food allocation in growing red kite (Milvus milvus) nestlings, whose dominance rank is largely dictated by age. We show that older siblings, irrespective of age, change from targeting only close-aged peers (close-competitor pattern) when food provisioning is low, to uniformly attacking all other peers (downward heuristic pattern) as food conditions improve. While food allocation was generally skewed towards the older siblings, the youngest sibling in the nest increased its probability of accessing food as more was provisioned and as downward heuristic patterns became more prominent, suggesting that different aggression patterns allow for catch-up growth after periods of low food. Our results indicate that dynamic aggression patterns within the nest modulate environmental effects on juvenile development by influencing the process of dominance acquisition and potentially impacting the fledging body condition, with far-reaching fitness consequences.

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Can regime shifts in reproduction be explained by changing climate and food availability?

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publicJun 2023View details →

opencc-zeroSep 2020View details →

Data from: Geographic location and food availability offer differing levels of influence on the bacterial communities associated with larval sea urchins

Determining the factors underlying the assembly, structure, and diversity of symbiont communities remains a focal point of animal-microbiome research. Much of these efforts focus on taxonomic variation of microbiota within or between animal populations, but rarely test the proportional impacts of ecological components that may affect animal-associated microbiota. Using larvae from the sea urchin Strongylocentrotus droebachiensis from the Atlantic and Pacific Oceans, we test the hypothesis that, under natural conditions, inter-population differences in the composition of larval-associated bacterial communities are larger than intra-population variation due to a heterogeneous feeding environment. Despite significant differences in bacterial community structure within each S. droebachiensis larval population based on food availability, development, phenotype, and time, variation in OTU membership and community composition correlated more strongly with geographic location. Moreover, 20-30% of OTUs associated with larvae were specific to a single location while less than 10% were shared. Taken together, these results suggest that inter-populational variation in symbiont communities may be more pronounced than intra-populational variation, and that this difference may suggest that broad scale ecological variables (e.g., across ocean basins) may mask smaller scale ecological variables (e.g., food availability).

opencc-zeroJan 2021View details →

Rwenzori colobus core unit SNA data - association scans between units, simple association index per dyad, male dispersal events, rainfall and food availability

1. 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. 2. The goal of our study was to determine the degree of temporal variability in inter-unit 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. 3. 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 inter-unit dispersals were correlated with these associations over the short-term (month to month) and long-term (year to year). 4. 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 post-dispersal. 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. 5. By examining temporal shifts in social network structure among core units, this study shows the inter-connected 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.

opencc-zeroDec 2017View details →

Data from: Feeding strategies of brown howler monkeys in response to variations in food availability

Primates display varying degrees of behavioral flexibility that allow them to adjust their diet to temporal changes in food availability. This trait might be critical for the survival of folivorous-frugivorous species inhabiting small forest fragments, where the availability of food resources tends to be lower than in large fragments and continuous forests. However, the scarcity of studies addressing this issue hampers our understanding of the adaptive behaviors that favor the survival of these primates in low-quality habitats. We conducted a 36-mo study testing the hypothesis that brown howler monkeys (Alouatta guariba clamitans) are able to adjust their diet in response to local and seasonal changes in resource availability. We compared the diet of six free-ranging groups inhabiting three small (<10 ha) and three large (>90 ha) Atlantic forest fragments in southern Brazil and estimated the temporal availability of their top food species (i.e., those species that together contribute ≥80% of total feeding records). We found that brown howlers exploited similarly rich diets in small (45, 54, and 57 plant species) and large (48, 51, and 56 species) fragments. However, intermonth diet similarity was higher for groups in small fragments, where howlers also fed on plant items from nine alien species. Fruits and leaves were the most consumed plant items in both small (42% and 49% of feeding records, respectively) and large (51% and 41%, respectively) fragments. The consumption of young leaves was higher in small than in large fragments, whereas the consumption of other plant items did not show a pattern related to fragment size. Regarding the contribution of growth forms as food sources, only the exploitation of palms showed a pattern related to fragment size. Palms contributed more to the diet of groups inhabiting large fragments. The availability of seasonal food items–ripe fruits and young leaves–influenced their consumption in both habitat types. Therefore, brown howlers cope with local and seasonal fluctuations in food availability by opportunistically exploiting resources. We believe that this feeding flexibility is a key component of the phenotypic plasticity that enables howlers to thrive in disturbed habitat patches, where periods of scarcity of preferred foods shall be more common.

opencc-zeroMay 2022View details →

Fruit-feeding butterfly populations respond to variation in adult food availability: evidence from longitudinal body mass and abundance data

The degree to which variation in adult food availability affects the population dynamics of a species depends on its position on the capital-income breeding continuum. The long-lived butterflies that feed on fruits as adults constitute an example of Lepidoptera with a high degree of income breeding. For three species of fruit-feeding butterflies in Uganda, we assessed the contribution of the income to breeding in the wild, and the consequences of variation in fruit availability for body mass and population dynamics. We interpreted body mass loss within individuals as well as younger individuals having higher body mass than older ones as evidence for the depletion of capital reserves. Despite large sample sizes, we were able to show only modest body mass loss in one species, indicating that large-bodied fruit-feeding butterflies are functionally income breeders in the wild. Butterfly body mass was sensitive to environmental factors, although the responses to fruit availability and weather parameters were dominated by interactive effects. In all three species, periods of higher availability of fruit were followed by periods of higher adult abundance three to five months later, fitting the egg-to-adult time. Our results suggest that adult food is rapidly used for reproduction so that body mass remains stable and population size responds to adult food availability. For these income breeding species, the frequent periods of low adult food availability may select for extended adult longevity for the purpose of postponing reproduction to the onset of more favorable conditions.

opencc-zeroOct 2022View details →

Data from: Effects of manipulated food availability and seasonality on innate immune function in a passerine

1. The innate immune system is essential for survival, yet many immune traits are highly variable between and within individuals. In recent years, attention has shifted to the role of environmental factors in modulating this variation. A key environmental factor is food availability, which plays a major role in shaping life-histories, and may affect resource allocation to immune function through its effect on nutritional state. 2. We developed a technique to permanently increase foraging costs in seed-eating birds, and leveraged this technique to study the effects of food availability on the innate immune system over a three-year period in 230 zebra finches housed in outdoor aviaries. The immune components we studied were haptoglobin, ovotransferrin, nitric oxide, natural antibodies through agglutination, complement-mediated lysis, and killing capacity of Escherichia coli and Candida albicans, covering a broad spectrum of the innate immune system. We explored effects of food availability in conjunction with other potentially important variables: season, age, sex, and manipulated natal brood size. 3. Increased foraging costs affected multiple components of the immune system, albeit in a variable way. Nitric oxide and agglutination levels were lower under harsh foraging conditions, while Escherichia coli killing capacity was increased. Agglutination levels also varied seasonally, but only at low foraging costs. C. albicans' killing capacity was lower in winter, and even more so for animals in harsh foraging conditions that were raised in large broods. Effects of food availability on ovotransferrin were also seasonal, and only apparent in males. Haptoglobin levels were independent of foraging costs and season. 4. Males had higher levels of immune function than females for 3 of the measured immune traits. Innate immune function was independent of age and manipulated natal brood size. 5. Our finding that food availability affects innate immune function suggests that fitness effects of food availability may at least partially be mediated by effects on the immune system. However, food availability effects on innate immunity varied in direction between traits, illustrating the complexity of the immune system and precluding conclusions on the level of disease resistance.