Valentina Franco-Trecu

Universidad de la República de Uruguay | UdelaR · Departamento de Ecología y Evolución

There are not "universal methods" to determine diet composition of predators. Most traditional methods are biased because of their reliance on differential digestibility and the recovery of hard items. By relying on assimilated food, stable isotope and Bayesian mixing models (SIMMs) resolve many biases of traditional methods. SIMMs can incorporate...

Males of polygynous mammalian species may adopt different reproductive tactics to accomplish female fertilization, with dominant males often attaining a higher reproductive success than those adopting alternative breeding tactics. We worked on the largest breeding colony of the South American fur seal to determine its mating system and quantify the...

• Individual specialisation could affect several ecological and evolutionary processes. Assessing isotopic data from different tissues of a single individual (multi‐tissue approach) represents a common method to estimate individual trophic specialisation (ITS). However, a neglected problem with this approach is that isotopic values of two tissues f...

Trophic niche width and individual specialization among marine predators are often subjected to seasonal constraints. Differences are expected to arise for sexually dimorphic species exposed to distinct ecological opportunities, as well as intrinsic differences in physiological abilities or energetic requirements. We assess seasonal and sexual diff...

1. The niche variation hypothesis (NVH) proposes that populations composed by trophic specialized individuals will show a wider population niche than populations composed by more “homogeneous” individuals. To the present, the NVH has little empirical support probably because most studies analyzing individual specialization were based on morphologic...

We report the first known occurrence of South American sea lion (Otaria flavescens) twins on the South American coast. In January 2021 a female pregnant with dizygotic male and female fetuses was found dead in southern Brazil. The timing of the stranding event suggests that the pregnancy was near-term. However, the total body length and weight of f...

Determining trophic habits of predator communities is essential to measure interspecific interactions and response to environmental fluctuations. South American fur seals, Arctocephalus australis (SAFS) and sea lions Otaria byronia (SASL), coexist along the coasts of Peru. Recently, ocean warming events (2014–2017) that can decrease and impoverish...

Marine mammals, regarded as sentinels of aquatic ecosystem health, are exposed to different pathogens and parasites under natural conditions. We surveyed live South American fur seals Arctocephalus australis and South American sea lions Otaria flavescens in Uruguay for Leoptospira spp., canine distemper virus (CDV), Mycobacterium spp., Toxoplasma g...

In the spider Paratrechalea ornata, males have two gift-giving mating tactics, offering either a nutritive (prey) or a worthless (prey leftovers) silk wrapped gift to females. Both gift types confer similar mating success and duration and afford males a higher success rate than when they offer no gift. If this lack of difference in the reproductive...

The aim of this study was to assess lipid disorders in children from five ethnic groups, both urban and indigenous, from northern and central Mexico. We measured the lipid profile to determine the ability of the body mass index (BMI) to discriminate an abnormally high lipid level using receiving operating characteristics (ROC). We analyzed the asso...

The Atlantic spotted dolphin (Stenella frontalis) is endemic to tropical, subtropical, and warm temperate waters of the Atlantic Ocean. Throughout its distribution, both geographic distance and environmental variation may contribute to population structure of the species. In this study we follow a seascape genetics approach to investigate populatio...

The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely...

We describe the foraging ecology of South American fur seals (Arctocephalus australis) at Isla de Lobos, Uruguay, the northernmost colony of the species in the Atlantic. We use multiple approaches to investigate diet and behavior at sea. South American fur seal females are epi- or meso-pelagic divers that feed on vertically migrating prey of high-e...

Hybridization that results from breeding with non-conspecifics occurs when both isolating mechanism, pre-breeding recognition and post-breeding gene incompatibilities, fail. Behavior often works to prevent hybridization. Despite these mechanisms, hybridization has been documented in the fur seals, among species within the genus Arctocephalus. We re...

Changes in the duration and frequency of foraging trips by female otariids may result in changes in the duration and frequency of lactation bouts and hence influence pup growth rate, unless females modify milk energy density and/or the total amount of milk delivered depending on the trip duration. To test this hypothesis on South American sea lions...

Marine mammals can play important ecological roles in aquatic ecosystems, and their presence can be key to community structure and function. Consequently, marine mammals are often considered indicators of ecosystem health and flagship species. Yet, historical population declines caused by exploitation, and additional current threats, such as climat...

Objective: We aimed to develop a program to treat and prevent obesity in schoolchildren, focused on improvements in physical fitness – both cardiorespiratory and musculoskeletal fitness. Methods: We assessed the effects of a school-based program on cardiorespiratory (VO2MAX) and musculoskeletal (Vertical Jump-VJ; Standing Long Jump-SLJ, and Sit-up...

In Mexico, the genetic mechanisms underlying childhood obesity are poorly known. We evaluated the effect of loci, known to be associated with childhood body mass index (BMI) in Europeans, in Mexican children from different ethnic groups. We performed linear and logistic analyses of BMI and obesity, respectively, in Mestizos and Amerindians (Seris,...

Realizar investigaciones científicas sobre la biología y ecología de animales silvestres mediante estudios a largo plazo, es una estrategia fundamental para una correcta conservación, gestión y uso sustentable de los recursos naturales. A diferencia de los modelos tradicionales usados en laboratorio, donde se buscan reactivos y condiciones biológic...

Background: Mexico occupies one of the first places worldwide in childhood obesity. Its Mestizo and Indigenous communities present different levels of westernization which have triggered different epidemiological diseases. We assessed the effects of a multi-component school-based intervention program on obesity, cardiovascular and diabetes risk fa...

Habitat fragmentation could alter ecological traits including species trophic habits. Here, we used carbon and nitrogen stable isotope ratios to establish differences in isotopic niche width and food resource use between forest fragments and the continuous forest for the phyllostomid frugivorous bat Artibeus lituratus. Using mist nests, we captured...

Alternative mating tactics are expected to occur predominantly when mate competition is intense, resources are in short supply, or as a result of asymmetric power relationships between individuals. Males of the nuptial gift-giving spider Pisaura mirabilis use a prevailing tactic of offering a nutritive gift (insect prey) and a deceptive tactic of o...

Fisheries interactions with non-target marine vertebrates are a worldwide problem. The impact of coastal bottom trawl fisheries on marine mammals has never been evaluated before in the Río de la Plata estuary and adjacent Atlantic Ocean. Our aim was estimate the bycatch per unit effort (BcPUE) and incidental mortality rates of marine mammals caused...

In Mexico, the increase in childhood obesity is alarming. Thus, improving the precision of its diagnosis is expected to impact on disease prevention. We estimated obesity prevalence by bioimpedance–based percent body fat (%BF) and body mass index (BMI) in 1061 girls and 1121 boys, from 3 to 17 years old. Multiple regressions and area under receiver...

Percentage body fat and body mass index, number (N), median (M), standard deviation (SD), coefficient of variation (CV) and box cox transformation parameter (L) for girls and boys and age. (DOCX)

Individual variation in habitat and resource use has been reported for many top predators. This variation becomes important when comparing individuals taking into account sex, size, or age classes, since it can influence population dynamics and stability. We evaluated the individual variation and sexual/geographical isotopic niche overlap of the So...

The systematics and phylogeny of Otariidae have been extensively studied for over two centuries. Yet, several relationships, in particular, the monophyly within Arctocephalus, remain unclear. Recent molecular phylogenies only used few concatenated mitochondrial or nuclear genes. Here we reconstructed the Otariidae phylogeny based on whole-genome se...

Here, we analyse changes throughout time in the isotopic niche of the Franciscana dolphin (Pontoporia blainvillei), the South American fur seal (Arctocephalus australis) and the South American sea lion (Otaria flavescens) from the Río de la Plata estuary and adjacent Atlantic Ocean to test the hypothesis that fishing may modify the diet of small-ga...

Pre diabetes mellitus (pre-DM) is considered an early-reversible condition that can progress to Type 2 diabetes mellitus (T2DM) which is the main cause of death for adult Mexican population. Gene variants influencing fasting glucose levels may constitute helpful tool for prevention purposes in pre-DM condition. Physically active Mexican-Mestizo adu...

1. Stable isotope analyses have become an important tool in reconstructing diets, analyzing resource use patterns, elucidating trophic relations among predators and understanding the structure of food webs. 2. Here, we use stable carbon and nitrogen isotope ratios in bone collagen to reconstruct and compare the isotopic niches of adult South Americ...

We analyzed commonly reported European and Asian obesity-related gene variants in a Mexican-mestizo population through each single nucleotide polymorphism (SNP) and a genetic risk score (GRS) based on 23 selected SNPs. Study subjects were physically active Mexican-mestizo adults (n=608) with body mass index (BMI) values from 18 to 55 kg/m2. For eac...

The South American fur seal (SAFS) is distributed from Peru (Pacific Ocean) to Uruguay (Atlantic Ocean). However, there is a section of coastline of about 2,300 km along the Chilean coast where no SAFS are recorded. Based on morphological comparisons 3 geographic forms have been reported (Peruvian, South Chilean, Atlantic), whereas preliminary gene...

Our understanding of how air-breathing marine predators cope with environmental variability is limited by our inadequate knowledge of their ecological and physiological parameters. Due to their wide distribution along both coasts of the sub-continent, South American sea lions (Otaria byronia) provide a valuable opportunity to study the behavioral a...

A species, according to the biological concept, is a natural group of potentially interbreeding individuals isolated by diverse mechanisms. Hybridization is considered the production of offspring resulting from the interbreeding of two genetically distinct taxa. It has been documented in over 10% of wild animals, and at least in 34 cases for Artic...

In mammals, the transition from a terrestrial to an aquatic environment has implied a great number of adaptations. While in terrestrial mammals the presentation of the foetus at birth is typically cephalic, in strictly aquatic mammals as cetaceans and sirenians the presentation of the foetus is mainly breech. The order Pinnipedia is the most recent...

Most otariids have colony-specific foraging areas during the breeding season, when they behave as central place foragers. However, they may disperse over broad areas after the breeding season and individuals from different colonies may share foraging grounds at that time. Here, stable isotope ratios in the skull bone of adult Galapagos sea lions (Z...

The spatio-temporal distribution of breeding males can help understand the existence of alternative reproductive tactics and their breeding success in colonially breeding species. We quantified the breeding success of South American sea lion (SASL) males in Uruguay according to their breeding location (tide line vs internal pool) in a rookery and a...

Many pinniped populations precipitously declined during the 19th and 20th centuries due to overharvesting. In Uruguay, the South American sea lion (SASL) was harvested until 1986. Birth rates in two nearby breeding colonies have had opposite trends for at least 20 years. We assessed different mechanisms that could explain opposite trends in birth r...

The South American Fur Seal, Arctocephalus australis, was severely depleted during the 18th century. This work updates information on distribution, abundance, seasonal movements, and genetic structure along the southwestern South Atlantic. Its distribution in Argentine waters includes nineteen rookeries on the Patagonian coast, Isla de los Estados...

RATIONALE: The use of accurate, species-specific diet-tissue discrimination factors is a critical requirement when applying stable isotope mixing models to predict the consumer diet composition. Thus, diet-to-female and female-to-pup isotopic discrimination factors in several tissues for both captive and wild South American sea lions were estimated...

Stable carbon and nitrogen isotopes in skin and bone of South American sea lions from Brazil and Uruguay were analysed to test the hypothesis that trophic overlap between sexes is lower during the pre-breeding season than during the rest of the year. The isotopic values of skin and bone were used to infer the trophic relationships between sexes dur...

Teeth and otoliths are metabolically inert structures that preserve a chronology of chemical variations that may be related to the environmental histories experienced by each organism. Because of the natural decrease of barium and increase of strontium bioavailability in water with increasing salinity, these elements may be especially useful to tra...

We found a segmented pattern, increasing for small sizes and decreasing for larger sizes, in the relationship between trophic position and body size. This pattern provides support to a theoretical model whose derivation was based on metabolic requirements and on basic assumptions about feeding relationships. We combined original and published infor...

Artisanal fisheries in Uruguay involve directly or indirectly more than 5,000 people and constitute the main source of income in several coastal communities. However, and despite its economic and environmental importance, this activity is poorly documented. As such, this scarcity of information constrains the understanding and effective management...

Individual specialisation is increasingly recognised to be an ecological and evolutionary process having important consequences for population dynamics of vertebrates. The South American fur seal (SAFS) and the South American sea lion (SASL) are two otariid species with similar ecology that coexist in sympatry in the Uruguayan coast. These two spec...

This communication reports a case of kidnapping and adoption of a pup by a South American fur seal female (Arctocephalus australis) while she was in labor, rejecting her own pup when it was born. The kidnapped pup was taken from its mother, who tried unsuccessfully to retrieve it. In the following month, the pup was observed nursing both from its m...

In Uruguay, the South American fur seal population (Arctocephalus australis) is increasing, whereas the South American sea lion (Otaria flavescens) population is declining. Previous research using fecal analysis suggested a high degree of trophic overlap between these species. In this study we used stable isotope analysis to assess whether trophic...

In some social mammals females feed alien offspring (allo-sucking, AS), a phenomenon rarely observed in otariids, possibly due to the existence of strict mother–pup recognition mechanisms. We studied the frequency of AS during the reproductive season in the largest South American fur seal rockery (in Uruguay). We recorded 57 AS attempts in 342 hr o...

ABSTRACT: The franciscana dolphin (Pontoporia blainvillei) is the most threatened small cetacean in the southwestern Atlantic Ocean. Its incidental capture in the Uruguayan fisheries of the Atlantic oceanic coast (AOC) has been recorded since 1940 and was systematically studied from 1974 to 1994, providing the most recent by-catch per unit of effor...