Body Size Preferences Research Articles

Male mate choice in mosquitofish: personality outweighs body size

BackgroundDespite its important implications in behavioural and evolutionary ecology, male mate choice has been poorly studied, and the relative contribution of personality and morphological traits remains largely unknown. We used standard two-choice mating trials to explore whether two personality traits (i.e., shyness and activity) and/or body size of both sexes affect mate choice in male mosquitofish Gambusia affinis. In the first set of trials involving 40 males, we tested whether males would prefer larger females and whether the preference would be affected by males’ body length and personality traits, and females’ activity level. In the second set of trials (using another 40 males), we tested whether males would prefer more active females and whether the preference would be affected by males’ body length and personality traits.ResultsBoth shyness and activity in males were significantly repeatable and constituted a behavioural syndrome. No overall directional preference for large (or small) females with the same activity levels was detected because larger males preferred larger females and smaller males chose smaller females. Males’ strength of preference for larger females was also positively correlated with the activity level of larger females but negatively with the activity level of smaller females. Males spent more time associating with active females regardless of their body lengths, indicating males’ selection was more influenced by female activity level than body size. Males’ preference for inactive females was enhanced when females became active. There was no convincing evidence for the effect of males’ personality traits or body length on their preferences for females’ activity level.ConclusionsOur study supports the importance of body size in male mate choice but highlights that personality traits may outweigh body size preferences when males choose mating partners.

A primer with purpose: Research implications of the objectification of weight in the workplace

We offer a primer for researchers who seek to carry out studies that evaluate the lived experience of larger‐bodied workers. We use objectification theory to describe the process by which intraculturally‐determined body size preferences impact how observers think about and react to larger‐bodied colleagues, and how these larger‐bodied colleagues internalize and cope with these judgements. Arguing that exploration of the objectification of larger‐bodied professionals is incomplete without the use of multidisciplinary lenses, we describe mechanisms that reinforce weight stigma, including the role of healthism‐based value systems, intersectionality, and body image. We conclude the primer by outlining areas for new research that highlights burgeoning applied demand for more nuanced, evidence‐based discussions of weight at work.Practitioner points In professional spaces, many workers feel comfortable “objectifying” their colleagues who occupy larger (i.e., “overweight”/”obese”) bodies. This means that workers (a) constantly compare their colleagues’ bodies to a “thin” standard, (b) feel a certain comfort in remarking on their larger‐bodied colleagues’ size, and (c) this judgment feeds into a cycle of self‐consciousness and self‐dislike that many larger‐bodied workers feel about themselves. This objectification process can be doubly harmful to the well‐being of larger‐bodied workers when they, too, occupy a secondary marginalized identity/ies, such as being female or of a minority ethnicity. The motivation for objectification comes from broader Western culture, which views the pursuit of health as a value that all people should pursue. Workers often assume their larger‐bodied colleagues are not pursuing health simply because of their size and can feel punitive toward them as a result. Organizational remedies for this objectification process include educational programming and training to talk about the myriad ways “health” may be realized; more precise information about the complex origin’s of one’s body size; education around how marginalization of larger‐bodied colleagues does not stimulate effective action, but instead harms these colleague’s mental health (and beyond).

Male secondary sexual traits do not predict female preference in Caribbean livebearing fishes (Limia)

AbstractFemale preference is widely described in various taxa, and the underlying mechanisms shaping preferences remain a major focus of sexual selection studies, particularly in species where males contribute minimally to offspring. Female preference is associated with maintaining male secondary sexual traits (SST). However, how male SST impact female preference is less‐understood. We hypothesized the strength of female preference should scale with the expression of male SST. To test this prediction, we compared female preference for male body size (an easily quantifiable trait that scales with other SST) in three species of Limia (Poeciliidae) varying in secondary sexual traits: L. perugiae, L. dominicensis and L. zonata. The degree of SST was assessed based on the amount of ornamentation and the presence of courtship in the species. Limia perugiae, L. dominicensis and L. zonata were designated as possessing high, intermediate and low male SST, respectively. Female preference was quantified as the relative amount of time females associated with males of various size classes: small, intermediate and large. Therefore, we predicted that because L. perugiae males have the most SST, females would associate more strongly with large males. Limia perugiae females were the only species to display female preference in relation to male body size, but they preferred small males. Although preference was observed, the direction of preference was unexpected. Moreover, the lack of preference for large male size and thereby other SST in the species suggests pre‐copulatory female preference is unimpacted by male SST in these species. We suggest cryptic female choice (i.e. preference enacted during or after copulation) may maintain costly male traits. However, future work remains necessary. The present study provides foundational behavioural work on Limia and examines the ubiquity of the evolution of female preference in poeciliids.

Age differences in preferences for body physique

Studies have demonstrated the importance of body weight in physical attractiveness, where thinness in women and leanness and muscularity in men are judged to be attractive. However, most research has focused on young adults, while less has investigated whether attractiveness judgments of body weight change with age. Here, we compared young and older adults' preferences for body physique in a Chinese population using 3D human body models. We found that the attractiveness judgments of body physique vary with age, where older adults have weaker preference for thinness in both male and female bodies than did young adults. These results present novel evidence that preferences for body size alters with age. We propose that the variation in preference for thinness is likely due to the difference in resource availability between generations.

Functional traits driving pollinator and predator responses to newly established grassland strips in agricultural landscapes

Abstract Agricultural biodiversity and associated ecosystem functions are declining at alarming rates due to widespread land use intensification. They can only be maintained through targeted landscape management that supports species with different habitat preferences, dispersal capacities and other functional traits that determine their survival. However, we need better understanding whether short‐term measures can already improve functional diversity in European agroecosystems. We investigated spatio‐temporal responses of bees (solitary bees, bumblebees and honey bees), hoverflies, carabid beetles and spiders to newly established grassland strips in Lower Austria over 3 years, and along a distance gradient to old grasslands. Specifically, we asked if new grasslands, compared to old grasslands and cereal fields, serve as temporal dispersal habitat or corridor, and how species‐specific traits affect dispersal patterns. Using a trait‐based functional diversity approach, we investigated year and distance effects for nine selected key traits per taxon (e.g. body size, feeding guild and habitat preferences). Our results show that the functional diversity of predators and pollinators (i.e. functional richness and evenness), as well as community‐weighted means of selected key traits in new grasslands significantly differed from adjacent cereal fields, but only slowly adjusted to adjacent old grasslands. These effects significantly decreased with increasing distance to old grasslands for carabids and spiders, but not for mobile bees and hoverflies. Synthesis and applications. Over 3 years, newly established grassland strips supported larger sized and actively foraging/hunting species in the agricultural landscape. Adjacent crops likely benefit from such measures through enhanced functional diversity and related ecosystem services. However, our results also suggest that 3‐year period is too short to enhance the occurrence of pollinators and epigeic predators in new grasslands. Agri‐environment measures need to be complemented by the conservation of permanent habitats to effectively maintain species and functional diversity. Our findings should be acknowledged by European policy and agricultural decision makers for the design of more effective agri‐environment schemes, taking into account trait‐dependent species responses to land use change.

Body size preferences for women and adolescent girls living in Africa: a mixed-methods systematic review.

To synthesise evidence on body size preferences for females living in Africa and the factors influencing these. Mixed-methods systematic review including searches on Medline, CINHAL, ASSIA, Web of Science and PsycINFO (PROSPERO CRD42015020509). A sequential-explanatory approach was used to integrate quantitative and qualitative findings. Urban and rural Africa. Studies of both sexes providing data on body size preferences for adolescent girls and women aged ≥10 years. Seventy-three articles from twenty-one countries were included: fifty quantitative, fifteen qualitative and eight mixed methods. Most studies reported a preference for normal or overweight body sizes. Some studies of adolescent girls/young women indicated a preference for underweight. Factors influencing preferences for large(r) body sizes included: socio-demographic (e.g. education, rural residency), health-related (e.g. current BMI, pubertal status), psycho-social (e.g. avoiding HIV stigma) and socio-cultural factors (e.g. spouse's preference, social standing, cultural norms). Factors influencing preferences for slim(mer) body sizes included: socio-demographic (e.g. higher socioeconomic status, urban residency, younger age), health-related (e.g. health knowledge, being nulliparous), psycho-social (e.g. appearance, body size perception as overweight/obese) and socio-cultural factors (e.g. peer pressure, media). Preference for overweight (not obese) body sizes among some African females means that interventions need to account for the array of factors that maintain these preferences. The widespread preference for normal weight is positive in public health terms, but the valorisation of underweight in adolescent girls/young women may lead to an increase in body dissatisfaction. Emphasis needs to be placed on education to prevent all forms of malnutrition.

Drivers of food consumption among overweight mother-child dyads in Malawi.

To address the increase in overweight and obesity among mothers and children in sub-Saharan Africa, an understanding of the factors that drive their food consumption is needed. We hypothesized food consumption in Malawi is driven by a combination of factors, including season, food accessibility (area of residence, convenience of purchasing food, female autonomy), food affordability (household resources, food expenditures, household food insecurity), food desirability (taste preferences, body size preferences), demographics, and morbidity. Participants in Lilongwe and Kasungu Districts were enrolled across three types of mother-child dyads: either the mother (n = 120), child (n = 80), or both (n = 74) were overweight. Seven-day dietary intake was assessed using a quantitative food frequency questionnaire during the dry and rainy seasons. Drivers associated with intake of calories, macronutrients, and 11 food groups at p<0.1 in univariate models were entered into separate multivariate linear regression models for each dietary intake outcome. Mother-child dyads with an overweight child had a higher percent of calories from carbohydrates and lower percent of calories from fat compared to dyads with a normal weight child (both p<0.01). These mothers also had the highest intake of grains (p<0.01) and their children had the lowest intake of oil/fat (p = 0.01). Household food insecurity, maternal taste preferences, and maternal body size preferences were the most consistent predictors of food group consumption. Household food insecurity was associated with lower intake of grains, fruits, meat and eggs, oil/fat, and snacks. Maternal taste preferences predicted increased consumption of grains, legumes/nuts, vegetables, fish, and oil/fat. Maternal body size preferences for herself and her child were associated with consumption of grains, legumes/nuts, dairy, and sweets. Predictors of food consumption varied by season, across food groups, and for mothers and children. In conclusion, indicators of food affordability and desirability were the most common predictors of food consumption among overweight mother-child dyads in Malawi.

The relationship between molar morphology and ecology withinNeotoma

AbstractThe extensive diversity in dental form across mammals and its strong relationship with function provides insights into the diet, habitat, and behavior, of both extant and extinct taxa. Understanding the extent of variation in dental morphology across species allows for more accurate identification of fossils and a better ability to infer relationships between form and function and ecology. We examined variation in the size and shape of the first upper molar among the genus Neotoma. We employed elliptical Fourier analysis to quantify differences in the shape of 2D outlines for 23 populations and six species of Neotoma, varying in body size and habitat preference. As expected, molar length is a strong predictor of body size and is significantly and negatively correlated with temperature, particularly in species whose ranges span large latitudinal gradients. We found that differences in molar shape separate species into three general morpho-groups, with no evidence of a phylogenetic signal. While outline analysis could not robustly classify all molars to the species level, it did perform well for Neotoma cinerea, probably because of the greater degree of folding and more acute angling of molar lophs. In contrast, wider lophs with shallower enamel infolding was characteristic of species specializing on softer, more succulent resources (i.e., Neotoma albigula and Neotoma micropus). Neotoma floridana were inaccurately classified to species in the majority of cases, but were the only molars correctly identified to locality 100% of the time, suggesting that dietary specializations at a local level may drive morphological changes within the species as well as across the genus.

A Physiologically Based Oiling Model (PBOM) to Predict Thermoregulatory Response in Birds

When birds are exposed to oil, their ability to thermoregulate is impaired as a result of damage to the insulative properties of their feathers. If an oiled bird is unable to maintain thermal homeostasis, hypothermia and death can follow rapidly. Physiological responses to oiling depend on several variables including environmental conditions (e.g., ambient air and water temperatures), life history of bird species (e.g., body size and habitat selection), and foraging strategies (e.g., divers, surface feeders, shorebirds). The most widely used approach to assess the effect of spilled oil on birds is the US Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Type A Natural Resource Damage Assessment (NRDA) Model for Coastal and Marine Environments. This approach addresses body size and time spent in a hypothetical slick but lacks the flexibility to assess other variables related to physiological response. We developed a dynamic physiologically based oiling model (PBOM) for birds to address this need. The PBOM has been validated against empirical data from a dose-response study in which common eiders were exposed to Statfjord A crude oil. The PBOM can be used to predict time to hypothermia for birds of differing body size and habitat preferences, in environments ranging from Arctic to subtropical. The model presently includes 5 representative bird species: common eider, spotted sandpiper, great blue heron, dovekie, and American white pelican, but could be adapted to represent almost any bird. Environ Toxicol Chem 2021;40:251-260. © 2020 SETAC.

Body size preferences and food choice among mothers and children in Malawi.

Overweight in mothers and children in sub‐Saharan Africa is rapidly increasing and may be related to body size perceptions and preferences. We enrolled 268 mother–child (6–59 months) pairs in central Malawi; 71% of mothers and 56% of children were overweight/obese, and the remainder were normal weight. Interviewers used seven body silhouette drawings and a questionnaire with open‐ and closed‐ended questions to measure mothers' perceptions of current, preferred and healthy maternal and child body sizes and their relation to food choices. Overweight/obese and normal weight mothers' correct identification of their current weight status (72% vs. 64%), preference for overweight/obese body size (68% both) and selection of an overweight/obese silhouette as healthy (94% vs. 96%) did not differ by weight status. Fewer overweight/obese than normal weight mothers' preferred body silhouette was larger than their current silhouette (74% vs. 29%, p < .001). More mothers of overweight than normal weight children correctly identified the child's current weight status (55% vs. 42%, p < .05) and preferred an overweight/obese body size for the child (70% vs. 58%, p < .01), and both groups selected overweight/obese silhouettes as healthy for children. More than half of mothers in both groups wanted their child to be larger than the current size. Mothers said that increasing consumption of fruits, vegetables, meat, milk, grains, fizzy drinks and fatty foods could facilitate weight gain, but many cannot afford to purchase some of these foods. Their desired strategies for increasing weight indicate that body size preferences may drive food choice but could be limited by affordability.

Does individual personality predict male mating preference for female body size in the Trinidadian guppy?

AbstractWithin populations, individual animals vary considerably in their behaviour, including mate choice and personality. There is mounting interest in the potential covariation between these two behaviours within individuals, such that personality would influence mate choice. We experimentally tested this proposition under controlled laboratory conditions using male Trinidadian guppies (Poecilia reticulata) as a model study system. We assayed repeatedly the mating preference of individual males for females based on their body size. Additionally, we assayed repeatedly two ecologically relevant personality traits in males, namely exploration of a novel environment and boldness under a simulated predation threat. Finally, we analysed whether male mating preference and personality traits were repeatable, and tested whether the personality of individual males was correlated (covaried) with their mating preference scores. Although all but one of the measures of exploration and boldness behaviour were repeatable over time, male mating preference scores were not repeatable. Measures of male exploration and boldness were not inter‐correlated among individuals, suggesting the absence of a behavioural syndrome between exploration and boldness. Unexpectedly, males did not exhibit on average a significant mating preference for larger females over smaller ones; they chose randomly between the paired stimulus females. Overall, we found no compelling evidence for a relationship between individual personality traits and mating preference in male guppies, suggesting that personality does not predict mate choice, at least in our study population and under our experimental conditions. We discuss potential factors, other than male personality and body length, that might maintain inter‐individual variation in male mating preferences in the guppy in the wild.

Diabetes Prevention for Pacific People in the United States: A Mixed-Methods Feasibility Study to Adapt the Diabetes Prevention Program With Samoan/Tongan Church Communities.

To determine baseline characteristics of a group of Samoans/Tongans in Southern California at risk for type 2 diabetes mellitus and identify barriers, cultural factors, and readiness and capacity to implement a culturally tailored Diabetes Prevention Program (DPP) in a faith-based setting. A mixed-methods pilot that included piloting modified DPP sessions, conducting a survey, and focus groups (N = 4). Samoan/Tongan faith-based organizations. Samoan/Tongan church members in Southern California who were interested in lifestyle behavior change. Surveys assessing sociodemographic, acculturation, health status, food insecurity, and psychosocial factors. Focus groups focusing on attitudes toward the curriculum, opportunities for tailoring, and specific barriers/facilitators for healthy weight, nutrition, and physical activity. Participants (N = 47) were on average 42 years old, female (57%), and identified as Pacific Islander (35% Samoan, 30% American Samoan, and 35% Tongan). Ninety-eight percent of respondents were overweight/obese, and 45% of households were food insecure. Less than half of respondents were born in the United States, and 28% reported "poor" or "fair" English proficiency. Those with higher body mass indexes were more likely to score lower on internal locus of control and self-efficacy for healthy eating and were motivated to lose weight to feel in control of their health. Focus group results revealed that members of the Samoan/Tongan communities are "underserved" and experience a lack of culturally relevant programs to address obesity and chronic disease. Several barriers to healthier lifestyles were identified including adaptation of traditional recipes made in the United States (ie, to be less healthy), role of stress, cultural values (eg, preference for larger body size), and lack of awareness about healthy lifestyles. The church was identified as a resource that could be leveraged further to positively impact health outcomes. Results demonstrate possible ways to tailor the DPP for US-based Samoan/Tongan populations by harnessing cultural traditions and addressing existing barriers and psychosocial constructs.

Functional diversity of chironomid communities in subarctic lakes across gradients in temperature and catchment characteristics

Northern ecosystems are experiencing rapid and large-scale changes driven by accelerated warming, which have profound effects on the terrestrial and freshwater biodiversity. A comprehensive understanding of the distribution of aquatic biodiversity of subarctic ecosystems is therefore needed to better predict future trajectories of their unique biodiversity. In this study, we examined the functional diversity of chironomid communities in subarctic lakes across a 1000 m-elevation gradient, reflecting gradual changes in temperature and landscape characteristics. Using fuzzy correspondence analyses, we investigated spatial variability in trait composition of chironomid communities from 100 lakes in northern Sweden, and tested the hypotheses that (1) climate directly and indirectly shapes chironomid trait composition across the studied gradient, and (2) that generalist taxa with smaller body size and broader food preferences are more able to persist in cold environments. Our results showed that complex interplays between direct (e.g. temperature) and indirect climate processes (e.g. elevation-driven changes in vegetation/habitats) affect the functional diversity of chironomid communities. Specifically, traits such as larval size, food preference and feeding habits were well separated along the gradient, and this pattern revealed that low elevation lakes with forested catchments tended to have more sediment-feeding taxa and larger larvae than those above the tree line. As expected, food resource availability in lakes is strongly linked to vegetation composition/cover, and traits related to resource exploitation in chironomid communities are therefore well constrained by landscape characteristics. Furthermore, our findings suggested that short life cycles could facilitate the development of viable population in northern and high-elevation lakes where the short ice-free period is a limiting factor, thus contradicting patterns showing smaller organisms in warmer environments reported for other invertebrates. As a consequence of climate warming, the highest elevation lakes in subarctic landscapes will likely lose their typical cold-adapted chironomid taxa along with their functional attributes leading to potential impacts on the food web structure and the overall functioning of northern lake ecosystems.

"The thing is, kids don't grow the same": Parent perspectives on preschoolers' weight and size in Soweto, South Africa.

The prevalence of overweight and obesity is high among preschool age (3–5 years) children in South Africa, and children in urban low-income settings are particularly at risk. A better understanding of how parents or caregivers of young children perceive children’s weight and size, as well as contextual factors influencing perceptions, is needed to inform interventions. The aim of this study was to examine how parents of preschool children in Soweto, South Africa, view childhood obesity, and to situate these perspectives in the context of the home environment in which preschool age children in Soweto live. Semi-structured in-depth interviews were conducted with 16 parents in four neighbourhoods of Soweto. Interviews were audio-recorded, transcribed verbatim, and analysed using reflexive thematic analysis following a contextualist approach. Three themes were developed: growing differently, the ‘right’ way to be, and weight is not health. These themes capture parents’ views on complex and reportedly inevitable causes of obesity, ideas about acceptable and preferred body sizes, and the low priority of weight per se compared to health. The findings suggest that childhood obesity prevention in South Africa needs to be done in a non-stigmatising way that recognises environmental and contextual factors, such as parents’ limited sense of agency in relation to their children’s health and weight, and concrete resource constraints. Environmental barriers to healthy behaviours need to be addressed in order to overcome the coexisting challenges of childhood undernutrition and obesity in urban low-income South African settings.

Body Weight, Obesity Perception, and Actions to Achieve Desired Weight among Rural and Urban Ghanaian Adults.

Background Accurate body weight perception is important to maintaining an ideal body weight. In Africa, a preference for a larger body size and its association with health and wellbeing has been well documented. It remains speculative if these perceptions have changed or improved and if differences exist among rural and urban dwellers. The main aim of this study was to assess the body weight and obesity perceptions among rural and urban Ghanaians. Methods This cross-sectional study involved 565 participants. The Stunkard figure rating scale was used to assess the body weight perception of participants. Participants were to choose from the scale figures they perceived to represent their current body weight, desired body weight, ideal body weight, ideal look for a wealthy person, ideal look for a woman with children, and ideal look for a woman without children. Additionally, participants were asked to describe obesity and its threat to health in their terms. Responses of participants to the above questions are presented as frequencies. Differences between rural and urban participants as well as males and females with respect to the median figure chosen for each question were determined by Mann–Whitney U test. Results The median age of participants was 40 (IQR 26). The prevalence of overweight and obesity observed among participants was 52.8%. The most frequently selected figure as current body image was figure 5 (23.5%). Figure 4 was most frequently chosen by both males (37.2%) and females (24.6%) as their desired body image (27.4%). Male participants (41.8%) chose figure 5 as ideal for their gender while females (27.4%) maintained figure 4 as ideal for their gender. Study participants associated overweight with wealth and childbirth, and attributed their current weights to hereditary (27%) and childbirth (27%). Most participants were not taking steps to achieve their desired body image, and only a few engaged in both dieting and exercise to lose weight. Majority of participants described obesity as the accumulation of fat (91.0%) and viewed it as a threat to health (91.0%). Differences were observed among rural and urban participants with regard to the figure chosen as ideal for a wealthy person. Conclusion Results from this study show an improvement in obesity perception and the acknowledgment of obesity as a threat to health. There was a desire for a normal-weight figure among study participants. Attribution of current body weight to hereditary and childbirth seems to be a hindrance to the implementation of actions to achieve this normal figure weight. Public health education, screening for overweight and obesity, creation of supportive food environments, and culture-sensitive interventions are promising to curbing the obesity menace.

Spiders (Arachnida: Araneae) in the semideciduous Atlantic Forest: An ecological and morphological trait dataset for functional studies.

BackgroundThe semideciduous Atlantic Forest is one of the most diverse ecosystems in the world with a great diversity of spiders. Most spider-related studies in this ecosystem focused on species richness and composition; however, little is known about their trait diversity (including morphological, ecological and/or physiological traits). Two main datasets were compiled to generate a complete record of spider traits for this ecosystem.New informationHere, we present two datasets about 259 species of spiders from the semideciduous Atlantic Forest of Argentina. The trait data set compiled information of morphological and ecological traits such as body size, femur length, ocular distance, foraging strategy, prey range, circadian activity and stratum preference; traits were assessed by species considering sexual dimorphism. The second dataset included information about phenology (season when spiders were collected), number of individuals assessed by species and presence/absence of spiders in the different sample sites. This dataset has high potential to help researchers in recording the state of a component of biodiversity (functional) and contributes with the study of ecosystem services and species conservation.

Changing body norms in the context of increasing body size: Samoa in 1995 and 2018.

To understand how body size preferences changed in Samoa between 1995 and 2017 to 2019. Data were from adults aged from 31 to 59 years, who participated in two separate cross-sectional studies of obesity and cardiometabolic risk conducted in Samoa in 1995 and 2017 to 2019. Participants nominated line drawings representing their current size, ideal size, the most attractive and healthiest size, and the lower/upper limits of "normal" size. In both sexes, body size preferences and perceived current average body size have increased, yet preference for bodies smaller than one's perceived current size has persisted. Furthermore, the range of body sizes that people considered "normal" has narrowed, suggesting decreased tolerance for extremes of body size. These findings may have implications for mental and physical health outcomes, inform development of future health initiatives, and contribute to a deeper understanding of how body norms and weight-related public health efforts interface.

Potential distribution and predator-prey interactions with terrestrial vertebrates of four pet commercialized exotic snakes in Mexico

The anthropogenic introduction of alien species is one of the main causes of biota homogenization worldwide. Part of these introductions provokes biological invasions, which cause serious ecological and economic impacts from local to global scales. In order to prevent this and give proper management to exotic species, it is necessary to use predictive tools to prioritize sites with a higher probability of their establishment, thus preventing impacts in local ecosystems and communities. Here, we used ecological niche and interaction models to estimate the invasive potential of four species of exotic snakes identified as high risk and currently sold as pets in Mexico (Python brongersmai, P. molurus, P. regius, and Malayopython reticulatus), and simulate their impact as top predators (according to the average length of the prey that each snake species consumes) of species of native terrestrial vertebrates to this country. Results indicate that all four exotic snake species could generate severe impact on the community of native vertebrates within the country, while P. molurus could get to cause the largest impact given that it would get to interact and potentially consume a greater number of species. The organisms that would be mostly preyed by these snakes would be birds, followed by mammals, reptiles and finally amphibians. This pattern results from a combination of factors including prey body size preferences for predation in the exotic snakes’ native ranges, and the amplitude of the potential distribution areas and the number of species from each vertebrate group in Mexico. This paper shows the utility of combining methodological approaches for risk prevention and risk analysis for invasive alien species.

Disentangling the coexistence strategies of mud-daubing wasp species through trophic analysis in oases of Baja California peninsula.

Species within the same trophic level show different strategies to avoid competition. Among these mechanisms, differences in body size, spatio-temporal segregation, and diet preference often leads to a niche partitioning. Nonetheless, little attention on coexisting predatory insects and their network interactions has been paid. In this study, we analyzed the strategies to avoid competition among three sympatric mud-daubing wasps of the genus Trypoxylon (Hymenoptera: Crabronidae) in oases and their surrounding xeric area from the Baja California peninsula, Mexico. We compared the prey richness, composition and proportion of spider guilds that were captured by the wasps. We tested whether the differences in wasp body size explained the niche breadth, niche overlap and the size of spider prey. We assessed the spider-wasp interactions through a network analysis. With the use of trap-nests, we collected 52 spider species captured by the wasps. Both the guild and species composition of preyed spiders was different between the three wasp species. Differential proportions in the capture of spider guilds and a little diet overlap were found among the wasp species. We found that the wasp body size was positively correlated with prey size, but it was not a proxy of niche breadth. Moreover, the largest wasp species was able to nest in both mesic and xeric habitats, while the two smaller species were restricted to the oases. This study reveals that the diversity of spiders in oases of Baja California peninsula is crucial to maintain highly specialized oasis-dependent wasp species. The niche partitioning between mud-daubing wasps can be shaped by their inherent body size limitations and hunting strategies through foraging specialization for specific spider guilds. Food selection and slight differences in body size reduce competition and allow the coexistence of sympatric wasps. Our study is the first approach exploring the interaction networks between mud-daubing wasps and their spider preys, highlighting new insights into the morphological and ecological factors that shape antagonistic interactions, and allow the coexistence of predators in deserts.

Limiting similarity in subterranean ecosystems: a case of niche differentiation in Elmidae (Coleoptera) from epigean and hypogean environments

Environmental pressures in caves can act on species, selecting functional attributes that allow their best performance in such habitats. Caves are simplified habitats, which makes them ideal for testing ecological models more accurately. From this perspective, we examined whether competition limits the morphological similarity among individuals of the species Heterelmis sp. and Hexacylloepus sp. (Coleoptera—Elmidae), along a surface-subterranean gradient. We used a Mann–Whitney test to assess morphological differences among individuals. Furthermore, we used the outlying mean index to explore the extent of niche overlap between the two species in surface and subterranean environments. The results indicate that in a cave environment, organisms avoid niche overlap by differing their body size and environmental preferences, and such avoidance is likely related to the increase of competitive interactions. Hence, it is plausible to assume that morphological modifications, such as increased body size, may occur in response to evolution within cave environments, partly due to the reduction of similarity between co-occurring species.