Andrew Sweet

Arkansas State University - Jonesboro | ASU · Department of Biological Sciences

Fruit flies (Tephritidae: Dacini) are a frugivorous insect group that exhibit high endemic diversity in the rainforests of Australia and the western Pacific. In this region, biogeography has been influenced by tectonic plate movements and cycles of isolation and re-connection of landmasses and rainforest habitats during glacial periods. However, ho...

Researchers often examine symbiont host specificity as a species-level pattern, but it can also be key to understanding processes occurring at the population level, which are not as well understood. The specialist-generalist variation hypothesis (SGVH) attempts to explain how host specificity influences population-level processes, stating that sing...

Many groups of parasites lack basic information on biodiversity and host associations, which poses challenges for conservation and understanding the ecological relationships between hosts and their parasites. This gap in knowledge is particularly relevant for parasitic species with obscure lifestyles. Ectoparasitc bird lice (Insecta: Psocodea: Phth...

Animal mitochondrial genomes (mitogenomes) typically exhibit a highly conserved gene content and organisation, with genes encoded on a single circular chromosome. However, many species of parasitic lice (Insecta: Phthiraptera) are notable exceptions, having mitogenomes fragmented into multiple circular chromosomes. To further understand the process...

A fundamental aspect of symbiotic relationships is host specificity, ranging from extreme specialists associated with only a single host species to generalists associated with many different species. Although symbionts with limited dispersal capabilities are expected to be host specialists, some are able to associate with multiple hosts. Understand...

Sequencing high molecular weight (HMW) DNA with long-read and linked-read technologies has promoted a major increase in more complete genome sequences for non-model organisms. Sequencing approaches that rely on HMW DNA have been limited to larger organisms or pools of multiple individuals, but recent advances have allowed for sequencing from indivi...

A fundamental aspect of symbiotic relationships is host specificity, ranging from extreme specialists associated with only a single host species to generalists associated with many different species. Although symbionts with limited dispersal abilities are typically host specialists, some are known to associate with multiple hosts, but our understan...

Host specificity is a key element to our understanding of symbiont diversification and is driven by multiple macro- and microevolutionary processes. Broad scale (e.g., species-level) studies can uncover relevant processes such as cospeciation and host-switching that shape host-symbiont evolutionary histories.

Dispersal is an important factor in shaping ecosystems and patterns of biodiversity. However, animals use several different modes of dispersal, each of which can have varying impacts on the ecology and evolutionary history of a group. One of these modes is phoresy, when an animal (the phorant) will temporarily attach itself to another animal (the h...

The mitochondrial genomes (mitogenomes) of bilaterian animals are highly conserved structures that usually consist of a single circular chromosome. However, several species of parasitic lice (Insecta: Phthiraptera) possess fragmented mitogenomes, where the mitochondrial genes are present on separate, circular chromosomes. Nevertheless, the extent,...

Host‐specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low host population densities and reduced among‐host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of dire...

The tribe Dacini (Diptera: Tephritidae) contains over 930 recognised species and has been widely studied due to the economic importance of some taxa, such as the Oriental fruit fly Bactrocera dorsalis. Despite the attention this group has received, very few phylogenetic reconstructions have comprehensively sampled taxa from a single biogeographic r...

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-...

Adaptive radiation is an important mechanism of organismal diversification and can be triggered by new ecological opportunities. Although poorly studied in this regard, parasites are an ideal group in which to study adaptive radiations because of their close associations with host species. Both experimental and comparative studies suggest that the...

Adaptive radiation is an important mechanism of organismal diversification, and can be triggered by new ecological opportunities. Although poorly studied in this regard, parasites present an ideal system to study adaptive radiations because of their close associations with host species. Both experimental and comparative studies suggest that the ect...

The study of ancient DNA is revolutionizing our understanding of paleo-ecology and the evolutionary history of species. Insects are essential components in many ecosystems and constitute the most diverse group of animals. Yet they are largely neglected in ancient DNA studies. We report the results of the first targeted investigation of insect ancie...

Parasitic lice have unique mitochondrial (mt) genomes characterized by rearranged gene orders, variable genome structures, and less AT content compared to most other insects. However, relatively little is known about the mt genomes of Amblycera, the suborder sister to all other parasitic lice. Comparing among nine different genera (including repres...

Organisms vary in their dispersal abilities, and these differences can have important biological consequences, such as impacting the likelihood of hybridization events. However, there is still much to learn about the factors influencing hybridization, and specifically how dispersal ability affects the opportunities for hybridization. Here, using th...

The insect order Psocodea is a diverse lineage comprising both parasitic (Phthiraptera) and non-parasitic members (Psocoptera). The extreme age and ecological diversity of the group may be associated with major genomic changes, such as base compositional biases expected to affect phylogenetic inference. Divergent morphology between parasitic and no...

The Philopterus Complex includes several lineages of lice that occur on birds. The complex includes the genera Philopterus (Nitzsch, 1818; Psocodea: Philopteridae), Philopteroides (Mey, 2004; Psocodea: Philopteridae), and many other lineages that have sometimes been regarded as separate genera. Only a few studies have investigated the phylogeny of...

Organisms vary in their dispersal abilities, and these differences can have important biological consequences, such as impacting the likelihood of hybridization events. However, there is still much to learn about the factors influencing hybridization, and specifically how dispersal ability affects the opportunities for hybridization. Here, using th...

Understanding both sides of host–parasite relationships can provide more complete insights into host and parasite biology in natural systems. For example, phylogenetic and population genetic comparisons between a group of hosts and their closely associated parasites can reveal patterns of host dispersal, interspecies interactions, and population st...

Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes (“minicircles”) are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species k...

Tinamous host the highest generic diversity of lice of any group of birds, as well as hosting representatives of all four avian feather louse ecomorphs. Although the generic diversity of tinamou feather lice is well documented, few attempts have been made to reconstruct the phylogenetic relationships among these lice. To test whether tinamou feathe...

Prior to this study, complete mitochondrial genomes from Order Thysanoptera were restricted to a single family, the Thripidae, resulting in a biased view of their evolution. Here we present the sequences for the mitochondrial genomes of four additional thrips species, adding three extra families and an additional subfamily, thus greatly improving t...

Nearly all lineages of birds host parasitic feather lice. Based on recent phylogenomic studies, the three major lineages of modern birds diverged from each other before the Cretaceous-Paleogene (K-Pg) mass extinction event. In contrast, studies of the phylogeny of feather lice on birds, indicate that these parasites diversified largely after this e...

Heteroptera is a diverse suborder of insects that includes many plant pests, human disease vectors, and nuisance pests, but also beneficial insects. Previous analyses have supported recognition of seven monophyletic infraorders. A clade comprising Leptopodomorpha, Pentatomomorpha, and Cimicomorpha is also well-accepted, but relationships among the...

The Bemisia tabaci complex of whiteflies contains globally important pests thought to contain cryptic species corresponding to geographically structured phylogenetic clades. Although mostly morphologically indistinguishable, differences have been shown to exist among populations in behavior, plant virus vector capacity, ability to hybridize, and DN...

Fruit doves and their allies are a diverse group within the pigeon and dove family (Aves: Columbidae). Progress towards subfamilial classification of Columbidae relies on identifying major groups and the phylogenetic relationships within these groups. One such recently proposed group is the Raphinae based on previous evidence that the extinct dodo...

The hemipteran suborder Auchenorrhyncha is a highly diverse, ecologically and agriculturally important group of primarily phytophagous insects which has been a source of phylogenetic contention for many years. Here, we have used transcriptome sequencing to assemble 2139 orthologues from 84 auchenorrhynchan species representing 27 families; this is...

Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes ("minicircles") are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species k...

Lice are considered a model system for studying the process of cospeciation because they are obligate and permanent parasites and are often highly host‐specific. Among lice, species in the family Echinophthiriidae Enderlein (Anoplura) are unique in that they infest mammalian hosts with an amphibious lifestyle, i.e. pinnipeds and the river otter. Th...

Aligning sequences for phylogenetic analysis (multiple sequence alignment; MSA) is an important, but increasingly computationally expensive step with the recent surge in DNA sequence data. Much of this sequence data is publicly available, but can be extremely fragmentary (i.e., a combination of full genomes and genomic fragments), which can compoun...

Parasite dispersal can shape host‐parasite interactions at both deep and shallow timescales. One approach to understanding the effects of dispersal is to study parasite lineages that differ in dispersal capability but are from the same group of hosts. We compared phylogenetic and population genetic patterns of wing and body lice from ground‐doves....

The diversity of permanent ectoparasites is likely underestimated due to the difficulty of collecting samples. Lice (Insecta: Phthiraptera) are permanent ectoparasites of birds and mammals; there are approximately 5,000 species described and many more undescribed, particularly in the Neotropics. We document the louse genera collected from birds sam...

Lice from Colombian and Peruvian birds

Previous molecular phylogenetic analyses and new analyses reported here demonstrate that the genus Claravis is not monophyletic and comprises two lineages, one with the species pretiosa Ferrari-Pérez, 1886 (Blue Ground-dove), and the other with two species: geoffroyi Temminck, 1811 (Purple-winged Ground-dove) and mondetoura Bonaparte, 1856 (Maroon-...

The diversification of parasite groups often occurs at the same time as the diversification of their hosts. However, most studies demonstrating this concordance only examine single host–parasite groups. Multiple diverse lineages of ectoparasitic lice occur across both birds and mammals. Here, we describe the evolutionary history of lice based on an...

Comparisons of host and parasite phylogenies often show varying degrees of phylogenetic congruence. However, few studies have rigorously explored the factors driving this variation. Multiple factors such as host or parasite morphology may govern the degree of phylogenetic congruence. An ideal analysis for understanding the factors correlated with c...

Parasite diversity accounts for most of the biodiversity on earth, and is shaped by many processes (e.g. cospeciation, host-switching). To identify the effects of the processes that shape parasite diversity, it is ideal to incorporate both deep (phylogenetic) and shallow (population) perspectives. To this end, we developed a novel workflow to obtai...

The mitochondrial genome arrangement in the insect order Psocodea (booklice, barklice, and parasitic lice) is extremely variable. Genome organization ranges from the rearrangement of a few tRNAs and protein coding genes, through extensive tRNA and protein coding gene rearrangements, to subdivision into multiple mini-chromosomes. Evolution of the ex...

Host-parasite coevolutionary histories can differ among multiple groups of parasites associated with the same group of hosts. For example, parasitic wing and body lice (Insecta: Phthiraptera) of New World pigeons and doves (Aves: Columbidae) differ in their cophylogenetic patterns, with body lice exhibiting higher phylogenetic congruence with their...

Parasitic "wing lice" (Phthiraptera: Columbicola) and their dove and pigeon hosts are a well-recognized model system for coevolutionary studies at the intersection of micro- and macroevolution. Selection on lice in microevolutionary time occurs as pigeons and doves defend themselves against lice by preening. In turn, behavioral and morphological ad...

The three species in the genus Claravis (Aves: Peristerinae) are unique among members of the small New World ground-dove clade. All three species inhabit forested areas rather than open scrubby habitat, and exhibit obvious sexual dichromatism. However, the phylogenetic relationships within Claravis remain unknown. The only molecular phylogenetic st...

Hosts-parasite interactions are plentiful and diverse, and understanding the patterns of these interactions can provide great insight into the evolutionary history of the organisms involved. Estimating the phylogenetic relationships of a group of parasites and comparing them to that of their hosts can indicate how factors such as host or parasite l...

Importance: Many insects are host to heritable symbiotic bacteria. These heritable bacteria have been identified from numerous species of parasitic lice. It appears that novel symbioses have formed between lice and bacteria many times, with new bacterial symbionts potentially replacing existing ones. However little was known about the symboints of...

Free-living organisms are often host to multiple lineages of closely related parasites. Different lineages of obligate parasites living on the same hosts might potentially be expected to display similar cophylogenetic patterns. However, there are also reasons why these lineages might have different evolutionary histories (e.g. host switching, host...

Documenting patterns of host specificity in parasites relies on the adequate definition of parasite species. In many cases, parasites have simplified morphology, making species delimitation based on traditional morphological characters difficult. Molecular data can help in assessing whether widespread parasites harbour cryptic species and, alternat...

South America has undergone many dramatic changes during the past 60 million years, which has had a major impact on the patterns of biological speciation and diversity in the region. Birds have been particularly affected, and major geologic events have been an important factor in generating avian diversity in the New World. Here we investigate the...

While parasitic lice (Insecta: Phthiraptera) have historically been an important model taxon for understanding host-parasite coevolution, very few molecular markers have been developed for phylogenetic analysis. The current markers are insufficient to resolve many of the deeper nodes in this group; therefore, sequences from additional genetic loci...