Leticia Avilés

University of British Columbia | UBC · Department of Zoology

Organisms capture energy to support growth, survival and reproduction in diverse ways. Larger metazoans require less energy per unit time and mass than smaller ones. Thus, structures animals build to capture energy need not scale isometrically with body size. Web-building spiders use silk structures of diverse geometries to capture energy, includin...

Animals exhibit a variety of strategies to avoid predation; spiders are no exception. We explored whether web-building spiders that differ in the architecture of their webs exhibit morphologies or behaviors suggestive of antipredator strategies that trade-off with the degree of protection offered by their webs. Spiders build webs of 3 types: the mo...

A defining feature of parasitism is the harm parasites cause to their host via a reduction in lifetime reproductive success. Harm, also referred to as “virulence,” may involve host mortality or sublethal effects, such as a decreased body condition or protracted development of immature individuals. We considered a system where colonies of the social...

The transition from solitary to social life is a major phenotypic innovation, but its genetic underpinnings are largely unknown. To identify genomic changes associated with this transition, we compare the genomes of 22 spider species representing eight recent and independent origins of sociality. Hundreds of genes tend to experience shifts in selec...

Abstract Organisms with lower dispersal abilities tend to have more genetically dissimilar populations. The same is true for parasites, whose transmission frequency may depend on the population structure of the host. This should be especially true when hosts and parasites face similar barriers to dispersal. Here, we considered the similarities betw...

Aim Along elevational or latitudinal gradients, the dynamics of mutualistic interactions may be driven by shifts in partner abundance, themselves driven by changes in environmental factors. We test the hypothesis that partner abundance mediates the frequency of associations and investment incurred by partners while associating. Location Western an...

The emergence of animal societies offers unsolved problems for both evolutionary and ecological studies. Social spiders are especially well suited to address this problem given their multiple independent origins and distinct geographic distribution. On the basis of long-term research on the spider genus Anelosimus, we developed a spatial model that...

Metabolic scaling, whereby larger individuals use less energy per unit mass than smaller ones, may apply to the combined metabolic rate of group‐living organisms as group size increases. Spiders that form groups in high disturbance environments can serve to test the hypothesis that economies of scale benefit social groups. Using solitary and group‐...

The evolution of social systems can place novel selective forces on investment in expensive neural tissue by changing cognitive demands. Previous hypotheses about the impact of sociality on neural investment have received equivocal support when tested across diverse taxonomic groups and social structures. We suggest previous models for social behav...

In response to the COVID-19 crisis, numerous academic conferences and seminars were moved online. Some remote (online) seminars have the aim to be maintained permanently after the pandemic, offering weekly opportunities for scientists, postdocs, and students to learn about research and to improve global networking. Remote seminars are a good option...

Animals may develop mutualistic associations with other species, whereby prey offer resources or services in exchange for protection from predators. Alternatively, prey may offer resources or services directly to their would-be predators in exchange for their lives. The latter may be the case of hemipterans that engage in mutualistic interactions w...

The transition from solitary to social life is a major phenotypic innovation, but its genetic underpinnings are largely unknown. To identify genomic changes associated with this transition, we compare the genomes of 22 spider species representing eight recent and independent origins of sociality. Hundreds of genes tend to experience shifts in selec...

An entry on social, colonial and subsocial spiders for the Encyclopedia of Social Insects, Living Edition, C. Starr, editor, Springer. Includes a review of special topics on the biology of social spiders—Why are they social? Inbreeding and Sociality in Spiders. Local and Global Dynamics in Social Spider Metapopulations. Female Biased Sex Ratios and...

Although the effects of abiotic factors on species distributions and habitat selection have been widely investigated, studies have rarely succeeded at identifying the factors behind selection at the microhabitat level. Spider webs are extended phenotypes expected to be subject to fitness trade‐offs. We tested the hypothesis that spiders with three‐...

Predation, which is a fundamental force in ecosystems, has been found to decrease in intensity with elevation and latitude. The mechanisms behind this pattern, however, remain unaddressed. Using visual sampling of potential predators and live flies as baits, we assessed predation patterns along 4,000-m elevation transects on either side of the equa...

1. Web building spider communities represent a vehicle for addressing how abiotic and biotic factors interact to structure natural communities. 2. The present study investigates how intense rainfall and potential predation by ants affect the proportion of three‐dimensional (3D) versus two‐dimensional (2D) spider webs along precipitation gradients....

1. Manipulation of host behaviour by parasitoids has long captured the imagination of ecologists. Parasitoid wasps in the Polysphincta group of genera develop as external parasitoids of spiders. 2. In the present study, the previously undescribed interaction between a Zatypota sp. wasp (Ichneumonidae) and a social spider Anelosimus eximius (Theridi...

Group living animals are likely to attract more parasites than solitary ones. Parasite loads, however, should also depend on environmental conditions and on host characteristics and behaviours. Previous work has found that social spider colonies harbour communities of kleptoparasitic spiders that forego building their own web and, instead, steal pr...

Negative frequency-dependent selection acting on the sexes is hypothesized to drive populations toward a balanced sex ratio. However, numerous examples of female-biased sex ratios pepper the arthropods. Theoretical examinations have proposed that female-biased populations or groups can have higher chances of surviving and propagating that may be ad...

Ineffective hunters in cooperative foraging groups may be shielded from natural selection by their more effective group mates, whereas those living solitarily would starve and thus be removed from the population. The problem may be exacerbated in large groups where it may be easier for individuals to withhold participation. Group foragers may thus...

Quantitative approaches to predator–prey interactions are central to understanding the structure of food webs and their dynamics. Different predatory strategies may influence the occurrence and strength of trophic interactions likely affecting the rates and magnitudes of energy and nutrient transfer between trophic levels and stoichiometry of preda...

Significance Ecological theory predicts that communities should contain species that exhibit little overlap in their use of resources, typically assuming differences in body size or morphology. Here we show that level of sociality—whether individuals live solitarily or in groups—can be a powerful dimension separating species in niche space. In 50+...

Metacommunity theory has advanced the understanding of the patterns and processes shaping community structure at multiple scales. Various models have been put forward to explain the relative effects of environmental filtering, dispersal, and species traits on community composition. Here, we focus on complex, three-dimensional webs of two social and...

1. Current models used to estimate insect prey biomass for diet studies use whole weight. However, a large proportion of an arthropod's body is taken up by an indigestible exoskeleton, leading to erroneous estimation of the food intake of insectivorous animals. 2. Linear mixed effect models were used to obtain equations to predict consumable biomas...

In some ways, social spiders are a biological novelty item. They are not extraordinarily successful either evolutionarily or ecologically, and their societies suffer a variety of disadvantages that render them more brittle than other social systems. Yet, from an empiricist's perspective, these attributes make them uniquely poised for addressing a v...

Group-living organisms offer a unique perspective on how environmental gradients influence geographic distributions, as not only the properties of individuals, but also those of their groups interact with the environment to determine a species range. In turn, the ranges of group-living organisms should provide insights on the conditions that favor...

Darwin famously described special difficulties in explaining social evolution in insects. More than a century later, the evolution of sociality - defined broadly as cooperative group living - remains one of the most intriguing problems in biology. Providing a unique perspective on the study of social evolution, this volume synthesizes the features...

There are many benefits of group living, but also substantial costs, one of which is competition for resources. How scarce food resources are distributed among different members of a population or social group – whether via scramble or contest competition – can influence not only the variance in individual fitness, but also the stability and theref...

Aim To evaluate the relative importance of environmental factors relevant to specific hypotheses that have been proposed to explain the distribution of social and subsocial A nelosimus spiders in the American continent and E cuador. For social species, we test the seasonality and prey size hypotheses, which posit that species forming long‐lived mul...

Reconstructing the dynamics of populations is complicated by the different types of stochasticity experienced by populations, in particular if some forms of stochasticity introduce bias in parameter estimation in addition to error. Identification of systematic biases is critical when determining whether the intrinsic dynamics of populations are sta...

We have previously shown that the range of prey sizes captured by co-occurring species of group-hunting social spiders correlates positively with their level of sociality. Here, we show that this pattern is probably caused by differences among species in colony size and the extent to which individuals participate in group hunting. We assess levels...

Alloparental care—the care of other’s offspring—is a key aspect of sociality in many groups of animals. Understanding how this complex behavior arises requires identifying both the selective forces that may favor it, as well as characteristics of particular lineages that facilitate or hinder its evolution. One potential hindrance is the existence o...

Examining community-wide patterns for the most diverse animal group, insects, is fundamental to our understanding of the ecological and evolutionary factors that maintain tropical diversity. Using several sampling techniques (malaise traps, pitfall traps, visual searches, and social spider nest captures), we investigated the day-night community com...

The question of why some social systems have evolved close inbreeding is particularly intriguing given expected short- and long-term negative effects of this breeding system. Using social spiders as a case study, we quantitatively show that the potential costs of avoiding inbreeding through dispersal and solitary living could have outweighed the co...

Species are often classified in discrete categories, such as solitary, subsocial, social and eusocial based on broad qualitative features of their social systems. Often, however, species fall between categories or species within a category may differ from one another in ways that beg for a quantitative measure of their sociality level. Here, we pro...

The consequences of population subdivision and inbreeding have been studied in many organisms, particularly in plants. However, most studies focus on the short-term consequences, such as inbreeding depression. To investigate the consequences of both population fragmentation and inbreeding for genetic variability in the longer term, we here make use...

Abstract The evolution of group living is regarded as a major evolutionary transition and is commonly met with correlated shifts in ancillary characters. We tested for associations between social tendency and a myriad of abiotic variables (e.g., temperature and precipitation) and behavioral traits (e.g., boldness, activity level, and aggression) in...

1. The evolution of sociality alters the genetic structure of populations, often leading to an increase in the level of inbreeding and a concomitant decrease in the ratio between the benefits and costs of dispersal. 2. The association between an absence of dispersal and sociality in spiders has so far been established indirectly from the age distri...

Explaining the evolution of sociality is challenging because social individuals face disadvantages that must be balanced by intrinsic benefits of living in a group. One potential route towards the evolution of sociality may emerge from the avoidance of dispersal, which can be risky in some environments. Although early studies found that local compe...

Species that differ in their social system, and thus in traits such as group size and dispersal timing, may differ in their use of resources along spatial, temporal, or dietary dimensions. The role of sociality in creating differences in habitat use is best explored by studying closely related species or socially polymorphic species that differ in...

Principal components analyses summaries and comparisons of species at each individual variable. (DOC)

Animals living in cooperative groups experience fundamentally different environments than their nonsocial relatives, potentially changing the strength of natural selection on some aspects of their behavior. Using a comparative approach, we examined a potential example of this phenomenon: an association between reduced levels of maternal care behavi...

Although discrete morphological castes are a rarity in animal societies, trait differences among group constituents are pervasive and can have similar effects on group function. Spider societies lack discrete morphological castes, but colony constituents can differ along any number of trait axes (e.g. body size). Here we tested for consistent indiv...

We examine the social characteristics and sex ratio of the recently described Anelosimus oritoyacu Agnarsson 2006. We find that this spider, whose nests occur on tree crowns and bushes in open fields near Baeza, Ecuador, lives in colonies that may contain from one to several thousand adult females and their progeny. It differs from most other socia...

We explored the role of group living and cooperation in resource use in a spider community where 4 congeneric species of similar body size, but with behaviors ranging from near-solitary to fully social, co-occur. We found that the range of insect sizes captured by each species reflected their nest and colony size so that species with larger colonie...

1. Body size and other morphological traits play key roles in an animal’s performance and thus their ability to locate, capture and handle different resources. For species that live and forage in groups, group-level characteristics, such as foraging group size and level of cooperation, may also influence performance and further shape resource use....

The transition to permanent-sociality in spiders is thought to have involved the suppression of the dispersal phase characteristic of hypothetical subsocial or periodic-social ancestral species. Extant periodic-social species may provide insights into this transition. The periodic-social Anelosimus jucundus in southern Arizona was found to form mot...

A first step toward understanding why sociality has evolved in a particular taxonomic group is to establish comparison points by studying the organization of different social systems. We examined the social organization and spatial distribution of individuals in colonies of the undescribed colonial spider Leucauge sp. (Araneae: Tetragnathidae). The...

The distribution and quantity of genetic diversity may be profoundly influenced by the emergence and dynamics of social groups. Permanent social living in spiders has resulted in the subdivision of their populations in more or less isolated colony lineages that grow, proliferate and become extinct without mixing with one another. A newly discovered...

Cooperation and grouping are regularly studied as separate traits. The evolution of sociality however requires both that individuals get together in groups and that they cooperate within them. Because the level of cooperation can influence selection for group size, and vice versa, it is worth studying how these traits coevolve. Using a generally ap...

Correlations in behavioural traits across time, situation and ecological context (i.e. 'behavioural syndromes' or 'personality') have been documented for a variety of behaviours, and in diverse taxa. Perhaps the most controversial inference from the behavioural syndromes literature is that correlated behaviour may act as an evolutionary constraint...

We explored the extent to which differences between elevations in arthropod composition – insects and arachnids – are reflected by different sampling methods and in the diet of local social and subsocial spiders. We surveyed two low‐elevation tropical rainforest and two upper montane cloud forest sites in eastern Ecuador using blacklighting, sweepi...

A decrease in the surface area per unit volume is a well known constraint setting limits to the size of organisms at both the cellular and whole-organismal levels. Similar constraints may apply to social groups as they grow in size. The communal three-dimensional webs that social spiders build function ecologically as single units that intercept pr...

Species range boundaries often form along environmental gradients that dictate the success of the phenotypes present in each habitat. Sociality may allow colonization of environments where related species with a solitary lifestyle cannot persist. Social spiders in the genus Anelosimus appear restricted to low- and mid-elevation moist environments i...

The evolution of cooperation requires benefits of group living to exceed costs. Hence, some components of fitness are expected to increase with increasing group size, whereas others may decrease because of competition among group members. The social spiders provide an excellent system to investigate the costs and benefits of group living: they occu...

To the extent that geography correlates with particular environmental parameters, the geographical distribution of phylogenetically related social and nonsocial organisms should shed light on the conditions that lead to sociality versus nonsociality. Social spiders are notorious for being concentrated in tropical regions of the world, occupying a s...

To the extent that geography correlates with particular environmental parameters, the geographical distribution of phylogenetically related social and nonsocial organisms should shed light on the conditions that lead to sociality versus nonsociality. Social spiders are notorious for being concentrated in tropical regions of the world, occupying a s...

1. Social species in the spider genus Anelosimus predominate in lowland tropical rainforests, while congeneric subsocial species occur at higher elevations or higher latitudes. 2. We conducted a comparative study to determine whether differences in total biomass, insect size or both have been responsible for this pattern. 3. We found that larger av...

Social and subsocial spiders of the genus Anelosimus exhibit an altitudinal pattern in their geographic distribution at tropical latitudes in the Americas. Social species, which capture prey cooperatively, occur primarily in the lowland rain forest and are absent from higher elevations, whereas subsocial species are common at higher elevations but...

We use fragments of three nuclear genes (Histone 3, 18SrDNA, and 28SrDNA) and three mitochondrial genes (16SrDNA, ND1, and COI) totalling approximately 4.5kb, in addition to morphological data, to estimate the phylogenetic relationships among Anelosimus spiders, well known for their sociality. The analysis includes 67 individuals representing 23 of...

1. There appears to be a pattern of decreasing sociality with increasing elevation across social spider species in the genus Anelosimus at tropical latitudes. Our data suggest that this pattern holds within a single species, Anelosimus eximius, on a smaller altitudinal gradient. 2. In comparing colony size at six different altitudes in north-easter...

Evolutionary "dead ends" result from traits that are selectively advantageous in the short term but ultimately result in lowered diversification rates of lineages. In spiders, 23 species scattered across eight families share a social system in which individuals live in colonies and cooperate in nest maintenance, prey capture, and brood care. Most o...

Permanent cooperative sociality is rare in spiders. Here we describe sociality in a cobweb (Theridiidae) genus with no other known social species. In five areas of eastern Ecuador, we found nests of Theridion nigroannulatum containing from a single to several thousand adults living together in a communal web. Spiders cooperated in prey capture and...

Social spiders are unusual among social organisms in being highly inbred-males and females mature within their natal nest and mate with each other to produce successive generations. Several lines of evidence suggest that in spiders inbred social species originated from outbred subsocial ancestors, a transition expected to have been hindered by inbr...

Male mating strategies are often deployed with regard to female maturity and receptivity, possibly in response to sperm utilization patterns on the part of the female. We examined the pattern of male residency with females during the mating period of the subsocial spider Anelosimus cf. jucundus (Araneae, Theridiidae). We first examined patterns of...

Why some social systems form groups composed of kin, while others do not, has gone largely untreated in the literature. Using an individual-based simulation model, we explore the demographic consequences of making kinship a criterion in group formation. We find that systems where social groups consist of one-generation breeding associations may fac...

Why some social systems form groups composed of kin, while others do not, has gone largely untreated in the literature. Using an individual‐based simulation model, we explore the demographic consequences of making kinship a criterion in group formation. We find that systems where social groups consist of one‐generation breeding associations may fac...

Species that alternate periods of solitary and social living may provide clues to the conditions that favor sociality. Social spiders probably originated from subsocial-like ancestors, species in which siblings remain together for part of their life cycle but disperse prior to mating. Exploring the factors that lead to dispersal in subsocial specie...

The soil nematode Caenorhabditis elegans is an example of a species in which self-fertilizing hermaphrodites predominate, but functional males continue to persist--allowing outcrossing to persevere at low levels. Hermaphrodites can produce male progeny as a consequence of sex chromosome non-disjunction or via outcrossing with males. Consequently, t...

One of the enduring problems in the study of social evolution has been to understand how cooperation can be maintained in the presence of freeloaders, individuals that take advantage of the more cooperative members of groups they are eager to join. The freeloader problem has been particularly troublesome when groups consist of nonrelatives, and no...

Using an individual-based and genetically explicit simulation model, we explore the evolution of sociality within a population-ecology and nonlinear-dynamics framework. Assuming that individual fitness is a unimodal function of group size and that cooperation may carry a relative fitness cost, we consider the evolution of one-generation breeding as...

We studied the temporal patterns of maturation and sexual receptivity of a subsocial spider, Anelosimus cf. jucundus, in southern Arizona. In subsocial spiders, sibling males and females share a common nest for a large portion of their life cycle, often only dispersing short distances close to the mating season. We found that, on average, male A. c...

Using an individual‐based and genetically explicit simulation model, we explore the evolution of sociality within a population‐ecology and nonlinear‐dynamics framework. Assuming that individual fitness is a unimodal function of group size and that cooperation may carry a relative fitness cost, we consider the evolution of one‐generation breeding as...

The Ecuadorian Amazon region is exceptionally rich in terms of the number and variety of social spiders it contains. In this area there are representatives of three of the four forms of social behavior described for spiders, comprising species in 10 genera and seven families. Here we review the natural history of the fourteen species from this area...