Herbivory increases diversification across insect clades.

Insects contain more than half of all living species, but the causes of their remarkable diversity remain poorly understood. Many authors have suggested that herbivory has accelerated diversification in many insect clades. However, others have questioned the role of herbivory in insect diversification. Here, we test the relationships between herbivory and insect diversification across multiple scales. We find a strong, positive relationship between herbivory and diversification among insect orders. However, herbivory explains less variation in diversification within some orders (Diptera, Hemiptera) or shows no significant relationship with diversification in others (Coleoptera, Hymenoptera, Orthoptera). Thus, we support the overall importance of herbivory for insect diversification, but also show that its impacts can vary across scales and clades. In summary, our results illuminate the causes of species richness patterns in a group containing most living species, and show the importance of ecological impacts on diversification in explaining the diversity of life

How a bird is an island

Replicate adaptive radiations occur when lineages repeatedly radiate and fill new but similar niches and converge phenotypically. While this is commonly seen in traditional island systems, it may also be present in host-parasite relationships, where hosts serve as islands. In a recent article in BMC Biology, Johnson and colleagues have produced the most extensive phylogeny of the avian lice (Ischnocera) to date, and find evidence for this pattern. This study opens the door to exploring adaptive radiations from a novel host-parasite perspective

Genes Involved in the Evolution of Herbivory by a Leaf-Mining, Drosophilid Fly

Herbivorous insects are among the most successful radiations of life. However, we know little about the processes underpinning the evolution of herbivory. We examined the evolution of herbivory in the fly, Scaptomyza flava, whose larvae are leaf miners on species of Brassicaceae, including the widely studied reference plant, Arabidopsis thaliana (Arabidopsis). Scaptomyza flava is phylogenetically nested within the paraphyletic genus Drosophila, and the whole genome sequences available for 12 species of Drosophila facilitated phylogenetic analysis and assembly of a transcriptome for S. flava. A time-calibrated phylogeny indicated that leaf mining in Scaptomyza evolved between 6 and 16 million years ago. Feeding assays showed that biosynthesis of glucosinolates, the major class of antiherbivore chemical defense compounds in mustard leaves, was upregulated by S. flava larval feeding. The presence of glucosinolates in wild-type (WT) Arabidopsis plants reduced S. flava larval weight gain and increased egg–adult development time relative to flies reared in glucosinolate knockout (GKO) plants. An analysis of gene expression differences in 5-day-old larvae reared on WT versus GKO plants showed a total of 341 transcripts that were differentially regulated by glucosinolate uptake in larval S. flava. Of these, approximately a third corresponded to homologs of Drosophila melanogaster genes associated with starvation, dietary toxin-, heat-, oxidation-, and aging-related stress. The upregulated transcripts exhibited elevated rates of protein evolution compared with unregulated transcripts. The remaining differentially regulated transcripts also contained a higher proportion of novel genes than the unregulated transcripts. Thus, the transition to herbivory in Scaptomyza appears to be coupled with the evolution of novel genes and the co-option of conserved stress-related genes.Organismic and Evolutionary Biolog

SNAPSHOT USA 2019 : a coordinated national camera trap survey of the United States

This article is protected by copyright. All rights reserved.With the accelerating pace of global change, it is imperative that we obtain rapid inventories of the status and distribution of wildlife for ecological inferences and conservation planning. To address this challenge, we launched the SNAPSHOT USA project, a collaborative survey of terrestrial wildlife populations using camera traps across the United States. For our first annual survey, we compiled data across all 50 states during a 14-week period (17 August - 24 November of 2019). We sampled wildlife at 1509 camera trap sites from 110 camera trap arrays covering 12 different ecoregions across four development zones. This effort resulted in 166,036 unique detections of 83 species of mammals and 17 species of birds. All images were processed through the Smithsonian's eMammal camera trap data repository and included an expert review phase to ensure taxonomic accuracy of data, resulting in each picture being reviewed at least twice. The results represent a timely and standardized camera trap survey of the USA. All of the 2019 survey data are made available herein. We are currently repeating surveys in fall 2020, opening up the opportunity to other institutions and cooperators to expand coverage of all the urban-wild gradients and ecophysiographic regions of the country. Future data will be available as the database is updated at eMammal.si.edu/snapshot-usa, as well as future data paper submissions. These data will be useful for local and macroecological research including the examination of community assembly, effects of environmental and anthropogenic landscape variables, effects of fragmentation and extinction debt dynamics, as well as species-specific population dynamics and conservation action plans. There are no copyright restrictions; please cite this paper when using the data for publication.Publisher PDFPeer reviewe

Inter-individual variability of stone marten behavioral responses to a highway

Efforts to reduce the negative impacts of roads on wildlife may be hindered if individuals within the population vary widely in their responses to roads and mitigation strategies ignore this variability. This knowledge is particularly important for medium-sized carnivores as they are vulnerable to road mortality, while also known to use available road passages (e.g., drainage culverts) for safely crossing highways. Our goal in this study was to assess whether this apparently contradictory pattern of high road-kill numbers associated with a regular use of road passages is attributable to the variation in behavioral responses toward the highway between individuals. We investigated the responses of seven radio-tracked stone martens (Martes foina) to a highway by measuring their utilization distribution, response turning angles and highway crossing patterns. We compared the observed responses to simulated movement parameterized by the observed space use and movement characteristics of each individual, but naı¨ve to the presence of the highway. Our results suggested that martens demonstrate a diversity of responses to the highway, including attraction, indifference, or avoidance. Martens also varied in their highway crossing patterns, with some crossing repeatedly at the same location (often coincident with highway passages). We suspect that the response variability derives from the individual’s familiarity of the landscape, including their awareness of highway passage locations. Because of these variable yet potentially attributable responses, we support the use of exclusionary fencing to guide transient (e.g., dispersers) individuals to existing passages to reduce the road-kill risk

Diversification and dispersal of the Hawaiian Drosophilidae: The evolution of Scaptomyza

The genus Scaptomyza is emerging as a model lineage in which to study biogeography and ecological adaptation. To place future research on these species into an evolutionary framework we present the most comprehensive phylogeny of Scaptomyza to date, based on 5042 bp of DNA sequence data and representatives from 13 of 21 subgenera. We find evidence that the lineage originated in the Hawaiian Islands and subsequently dispersed to the mainland and other remote oceanic islands. We also identify that many of the unique ecological niches exploited by this lineage (e.g., herbivory, spider predation) arose singly and independently. We find strong support for the monophyly of almost all subgenera with exceptions corroborating hypotheses of conflict inferred from previous taxonomic studies

Diversification in the Hawaiian Drosophila

The Hawaiian Islands have been recognized as an ideal place to study evolutionary processes due to their remote location, multitude of ecological niches and diverse biota. As the oldest and largest radiation in the Hawaiian Islands the Hawaiian Drosophilidae have been the focus of decades of evolutionary research and subsequently the basis for understanding how much of the diversity within these islands and other island systems have been generated. This dissertation revolves around the diversification of a large clade of Hawaiian Drosophila, and examines the molecular evolution of this group at several different temporal scales. The antopocerus, modified tarsus, ciliated tarsus (AMC) clade is a group of 90 described Drosophila species that utilize decaying leafs as a host substrate and are characterized by a set of diagnostic secondary sexual characters: modifications in either antennal or tarsal morphologies. This research uses both phylogenetic and population genetic methods to study how this clade has evolved at increasingly finer evolutionary scales, from lineage to population level. The first chapter resolves the relationships within the AMC lineage, delimiting species group and subgroup relationships for the first time. This work complements recent phylogenetic studies focused on other lineages of Hawaiian Drosophila, most notably of the picture wing clade. This dissertation presents the most comprehensively sampled data set for the AMC in terms of both species and phylogenetic characters. The AMC clade is strongly supported as monophyletic and relationships among of the five major lineages in this radiation are proposed. Molecular dating analyses indicate a rapid radiation occurred about four million years ago, giving rise to all the extent lineages of AMC species. Interestingly, the AMC does not strictly follow the progression rule common to many other Hawaiian taxa. By comparing this lineage to other Hawaiian Drosophila lineages it is hypothesized that an initial burst of speciation occurred following colonization of the main Hawaiian Islands ands its magnitude was correlated with sexual selection within each group. Focusing more specifically on the spoon tarsus subgroup within the AMC, I redescribe this subgroup in chapter two. The species boundaries in this group are discussed in light of diagnostic secondary sexual characters of males. Drosophila septuosa Hardy is regarded as a junior synonym of Drosophila percnosoma Hardy. A new species, Drosophila kikalaeleele, is described. Drosophila fastigata Hardy, a species endemic to O`ahu, is added to the species subgroup, bringing the total number of known species to 12. An updated key to species is provided to the spoon tarsus subgroup. I employ several methods to delimit relationships at the species/population interface to get a more refined view of the evolution of this subgroup in chapter three. Eight of the twelve species in this subgroup are found only on the Island of Hawaii, suggesting that they have diverged within the past 500,000 years. This rapid diversification has made determining the relationships within this group difficult. We find widespread agreement between phylogenetic estimates derived from different methods. Notably, our analyses suggest that the spoon tarsus subgroup, as currently defined, is not monophyletic. The last chapter in this dissertation explores how biogeography influences microevolution within the spoon tarsus species, Drosophila waddingtoni, to understand the forces that drive macroevolution within the AMC clade. Previous chapters show that D. waddingtoni originated on the youngest island, Hawaii, and subsequently colonized the older islands of the Maui Nui complex, the opposite direction predicted by the progression rule. The recent origin of Hawaii suggests that this species will provide unique insight into the dynamics of recent island colonization events. Three nuclear and three mitochondrial genes are used to study gene flow and divergence following founder events. Biogeographic patterns, coupled with divergence time estimates suggest that the back colonization to Maui Nui occurred within the past 250,000 years and has since not led to significant population differentiation. These data also demonstrate that while migration between islands is possible and present in this species, it is not frequent enough to homogenize populations. Biogeography is identified as being a major driver in the diversification of this species. The AMC clade is a useful tool in understanding diversification in the Hawaiian Islands and rapid radiations in general. By examining this lineage from several different evolutionary timescales this dissertation research elucidates the processes involved in generating and maintaining diversity at all taxonomic levels. This research is also useful in extrapolating how evolution drives diversity in other Hawaiian Drosophilidae clades and other native Hawaiian lineages as well