Andrea Lucky

A jungle in there: bacteria in belly buttons are highly diverse, but predictable.

The belly button is one of the habitats closest to us, and yet it remains relatively unexplored. We analyzed bacteria and arachaea from the belly buttons of humans from two different populations sampled within a nation-wide citizen science project. We examined bacterial and archaeal phylotypes present and their diversity using multiplex pyrosequencing of 16S rDNA libraries. We then tested the oligarchy hypothesis borrowed from tropical macroecology, namely that the frequency of phylotypes in one sample of humans predicts its frequency in another independent sample. We also tested the predictions that frequent phylotypes (the oligarchs) tend to be common when present, and tend to be more phylogenetically clustered than rare phylotypes. Once rarefied to four hundred reads per sample, bacterial communities from belly buttons proved to be at least as diverse as communities known from other skin studies (on average 67 bacterial phylotypes per belly button). However, the belly button communities were strongly dominated by a few taxa: only 6 phylotypes occurred on >80% humans. While these frequent bacterial phylotypes (the archaea were all rare) are a tiny part of the total diversity of bacteria in human navels (<0.3% of phylotypes), they constitute a major portion of individual reads (∼1/3), and are predictable among independent samples of humans, in terms of both the occurrence and evolutionary relatedness (more closely related than randomly drawn equal sets of phylotypes). Thus, the hypothesis that “oligarchs” dominate diverse assemblages appears to be supported by human-associated bacteria. Although it remains difficult to predict which species of bacteria might be found on a particular human, predicting which species are most frequent (or rare) seems more straightforward, at least for those species living in belly buttons.

Breaking out of biogeographical modules: range expansion and taxon cycles in the hyperdiverse ant genus Pheidole

Abstract Aim We sought to reconstruct the biogeographical structure and dynamics of a hyperdiverse ant genus, Pheidole, and to test several predictions of the taxon cycle hypothesis. Using large datasets on Pheidole geographical distributions and phylogeny, we (1) inferred patterns of biogeographical modularity (clusters of areas with similar faunal composition), (2) tested whether species in open habitats are more likely to be expanding their range beyond module boundaries, and (3) tested whether there is a bias of lineage flow from high‐ to low‐diversity areas. Location The Old World. Methods We compiled and jointly analysed a comprehensive database of Pheidole geographical distributions, the ecological affinities of different species, and a multilocus phylogeny of the Old World radiation. We used network modularity methods to infer biogeographical structure in the genus and comparative methods to evaluate the hypotheses. Results The network analysis identified eight biogeographical modules, and a suite of species with anomalous ranges that are statistically more likely to occur in open habitat, supporting the hypothesis that open habitats promote range expansion. Phylogenetic analysis shows evidence for a cascade pattern of colonization from Asia to New Guinea to the Pacific, but no ‘upstream’ colonization in the reverse direction. Main conclusions The distributions of Pheidole lineages in the Old World are highly modular, with modules generally corresponding to biogeographical regions inferred in other groups of organisms. However, some lineages have expanded their ranges across module boundaries, and these species are more likely to be adapted to open habitats rather than interior forest. In addition, there is a cascade pattern of dispersal from higher to lower diversity areas during these range expansions. Our findings are consistent with the taxon cycle hypothesis, although they do not rule out alternative interpretations.

Climate mediates the effects of disturbance on ant assemblage structure

Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 9°C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk.

Tracing the Rise of Ants - Out of the Ground

The evolution of ants (Hymenoptera: Formicidae) is increasingly well-understood due to recent phylogenetic analyses, along with estimates of divergence times and diversification rates. Yet, leading hypotheses regarding the ancestral habitat of ants conflict with new findings that early ant lineages are cryptic and subterranean. Where the ants evolved, in respect to habitat, and how habitat shifts took place over time have not been formally tested. Here, we reconstruct the habitat transitions of crown-group ants through time, focusing on where they nest and forage (in the canopy, litter, or soil). Based on ancestral character reconstructions, we show that in contrast to the current consensus based on verbal arguments that ants evolved in tropical leaf litter, the soil is supported as the ancestral stratum of all ants. We also find subsequent movements up into the litter and, in some cases, into the canopy. Given the global importance of ants, because of their diversity, ecological influence and status as the most successful eusocial lineage on Earth, understanding the early evolution of this lineage provides insight into the factors that made this group so successful today.

Ecologists, educators, and writers collaborate with the public to assess backyard diversity in The School of Ants Project

Citizen science can generate data that would not exist otherwise while increasing public scientific literacy. However, the quality and use of citizen science data have been criticized in the recent ecological literature. We need an approach that advances eco-evolutionary understanding, achieves education goals and incorporates public participation into as many aspects of the scientific process as possible. We collaborated with public participants to make new discoveries about the distribution and ecology of ants while informing the next studies that participants and scientists might perform together. We implemented the School of Ants (SoA) program in which participants sample ants that are identified by taxonomic experts. Using a comprehensive framework that meets the needs of multiple agents, we also developed outreach materials about ant biology, collaborated with educators to incorporate SoA into classroom science, and launched an international SoA module in Italy. In the first 17 months, SoA volunteers collected ants at 500 unique sites across the USA-including all 50 states and Washington, D.C. To address concerns about the validity of citizen scientist-derived data, we conducted a ground truthing trial that confirmed that trained and untrained volunteers were equally effective at collecting ants. Data from SoA samples indicate that ant diversity varies across wide geographic scales and that there can be high levels of native ant diversity where people live. SoA volunteers collected 7 exotic and 107 native ant species. Although exotic ants were common, ants native to North America occurred in ∼70% of all sites. Many of the ants common in backyards were species that tend to be very poorly studied. For example, citizen scientists documented a range extension of more than 2000 miles for the Asian Needle Ant, Pachycondyla chinensis. Using SoA data as a starting point, we collaborated with a science writer to produce a free, interactive iBook about the common ants in North America; the book included distribution maps such as that for P. chinensis informed by participant collections. Moving forward, we plan to leverage this existing framework to address more complex ecological and evolutionary questions in partnership with our public participants.

A global database of ant species abundances

What forces structure ecological assemblages? A key limitation to general insights about assemblage structure is the availability of data that are collected at a small spatial grain (local assemblages) and a large spatial extent (global coverage). Here, we present published and unpublished data from 51 ,388 ant abundance and occurrence records of more than 2,693 species and 7,953 morphospecies from local assemblages collected at 4,212 locations around the world. Ants were selected because they are diverse and abundant globally, comprise a large fraction of animal biomass in most terrestrial communities, and are key contributors to a range of ecosystem functions. Data were collected between 1949 and 2014, and include, for each geo-referenced sampling site, both the identity of the ants collected and details of sampling design, habitat type, and degree of disturbance. The aim of compiling this data set was to provide comprehensive species abundance data in order to test relationships between assemblage structure and environmental and biogeographic factors. Data were collected using a variety of standardized methods, such as pitfall and Winkler traps, and will be valuable for studies investigating large-scale forces structuring local assemblages. Understanding such relationships is particularly critical under current rates of global change. We encourage authors holding additional data on systematically collected ant assemblages, especially those in dry and cold, and remote areas, to contact us and contribute their data to this growing data set.

School of Ants goes to college: integrating citizen science into the general education classroom increases engagement with science

Citizen science has proven useful in advancing scientific research, but participant learning outcomes are not often assessed. This case study describes the implementation and tailoring of an in-depth assessment of the educational impact of two citizen science projects in an undergraduate, general education course. Mixed-methods assessment of citizen science within a college classroom demonstrates that public participation in scientific research can positively alter attitudes towards science. The timing and type of assessments yielded significantly different results and qualitative assessment provided depth and context. However, disentangling the impact of the course from participation in the projects is the biggest challenge. Abstract

Dominance-diversity relationships in ant communities differ with invasion

The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance-impoverishment rule states that high levels of dominance only occur in species-poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which dominant species limit local richness through competitive exclusion remains unclear, but such exclusion appears more apparent for non-native rather than native dominant species. Here we perform the first global analysis of the relationship between behavioral dominance and species richness. We used data from 1,293 local assemblages of ground-dwelling ants distributed across five continents to document the generality of the dominance-impoverishment rule, and to identify the biotic and abiotic conditions under which it does and does not apply. We found that the behavioral dominance-diversity relationship varies greatly, and depends on whether dominant species are native or non-native, whether dominance is considered as occurrence or relative abundance, and on variation in mean annual temperature. There were declines in diversity with increasing dominance in invaded communities, but diversity increased with increasing dominance in native communities. These patterns occur along the global temperature gradient. However, positive and negative relationships are strongest in the hottest sites. We also found that climate regulates the degree of behavioral dominance, but differently from how it shapes species richness. Our findings imply that, despite strong competitive interactions among ants, competitive exclusion is not a major driver of local richness in native ant communities. Although the dominance-impoverishment rule applies to invaded communities, we propose an alternative dominance-diversification rule for native communities.

Alternative preservatives of insect DNA for citizen science and other low-cost applications

Abstract. Prevention of DNA degradation is essential to conducting molecular analyses of field-captured specimens. This is especially important for projects that incorporate participation of non-specialists in research, such as agency monitoring of pests, or citizen science, where standard methods of preservation may be inaccessible. We examined efficacy of three common alternative products as a substitute for 95% ethanol or pure propylene glycol in preserving DNA: alcohol-based hand sanitiser and propylene and ethylene glycol-based automobile antifreeze. We subjected Xylosandrus compactus ambrosia beetles (Coleoptera : Curculionidae : Scolytinae) to each preservative for two or seven days under direct outdoor exposure and assessed relative quantity of intact DNA by performing real-time polymerase chain reaction amplification of a single-copy nuclear marker. Amplification was observed in all treatments and electrophoresis of the amplified product showed clear bands of the appropriate weight. Successful amplification of the target gene was verified by sequencing the amplified control. No statistically significant differences were found between the cycle threshold values of any treatment. Our results suggest that alcohol-based hand sanitiser and automobile antifreeze can successfully preserve DNA for short-term storage and serve as effective substitutes for laboratory-grade preservatives in citizen science projects, large-scale trapping projects or by professionals.

Managed Fire Frequency Significantly Influences the Litter Arthropod Community in Longleaf Pine Flatwoods

Abstract Frequent prescribed burns are essential to pine forest restoration and management. Research studies have assessed effects of prescribed fire and burn frequency on plants and vertebrates, but impacts of fire on terrestrial invertebrate communities are still poorly understood. This case study investigated effects of burning frequency on species richness and community composition of social insects (ants, Hymenoptera: Formicidae and termites, Blattodea: Isoptera) in fire-managed Southern longleaf pine flatwoods in central Florida. Community response to different fire frequencies was assessed: burned annually, every 2 yr, or every 3 yr, 30 yr unburned and 75 yr unburned. Richness was similar across all treatments, but ant community composition and species density significantly differed between frequently burned (1, 2, and 3 yr) and long-unburned (30 and 75 yr) treatments. Long-unburned treatments had higher ant abundance, but the species present were less characteristic of open canopy longleaf pine habitat than ants in frequently burned treatments. The annual burn treatment differed from 2-yr burn in species density, but to a lesser degree. Exotic species abundance was highest in frequently burned sites; only native species were detected in the 75-yr unburned plot. The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), was detected in all regularly burned plots but not in long-unburned sites. Frequent burning at this site increased habitat suitability for ant species adapted to the sunny, open canopy, and diverse niches characteristic of longleaf pine forest; however, regular fire disturbance also increased the likelihood of exotic ant species establishment.