Eric G. Chapman

Evolutionary transitions among dioecy, androdioecy and hermaphroditism in limnadiid clam shrimp (Branchiopoda: Spinicaudata)

Examinations of breeding system transitions have primarily concentrated on the transition from hermaphroditism to dioecy, likely because of the preponderance of this transition within flowering plants. Fewer studies have considered the reverse transition: dioecy to hermaphroditism. A fruitful approach to studying this latter transition can be sought by studying clades in which transitions between dioecy and hermaphroditism have occurred multiple times. Freshwater crustaceans in the family Limnadiidae comprise dioecious, hermaphroditic and androdioecious (males + hermaphrodites) species, and thus this family represents an excellent model system for the assessment of the evolutionary transitions between these related breeding systems. Herein we report a phylogenetic assessment of breeding system transitions within the family using a total evidence comparative approach. We find that dioecy is the ancestral breeding system for the Limnadiidae and that a minimum of two independent transitions from dioecy to hermaphroditism occurred within this family, leading to (1) a Holarctic, all‐hermaphrodite species, Limnadia lenticularis and (2) mixtures of hermaphrodites and males in the genus Eulimnadia. Both hermaphroditic derivatives are essentially females with only a small amount of energy allocated to male function. Within Eulimnadia, we find several all‐hermaphrodite populations/species that have been independently derived at least twice from androdioecious progenitors within this genus. We discuss two adaptive (based on the notion of ‘reproductive assurance’) and one nonadaptive explanations for the derivation of all‐hermaphroditism from androdioecy. We propose that L. lenticularis likely represents an all‐hermaphrodite species that was derived from an androdioecious ancestor, much like the all‐hermaphrodite populations derived from androdioecy currently observed within the Eulimnadia. Finally, we note that the proposed hypotheses for the dioecy to hermaphroditism transition are unable to explain the derivation of a fully functional, outcrossing hermaphroditic species from a dioecious progenitor.

MIDGE LARVAE (DIPTERA: CHIRONOMIDAE) AS INDICATORS OF POSTMORTEM SUBMERSION INTERVAL OF CARCASSES IN A WOODLAND STREAM : A PRELIMINARY REPORT

Data on colonization of rat carcasses by aquatic insects in riffle and pool areas of a small woodland stream were obtained to elucidate patterns potentially useful for determining the postmortem submersion interval of corpses in flowing water habitats. After 39 days, the carcasses had no visual signs of deterioration in the absence of large scavenging animals. Midge larvae (Diptera: Chironomidae) were the dominant insects colonizing the carcasses. No patterns in numbers of larvae over time were evident, but the diversity of genera increased after 29 days in the riffle. Also, Orthocladius larvae did not begin to colonize the carcasses until after 13 days of submersion in the riffle and after 20 days of submersion in the pool. Although separated only by 20 m, the riffle and pool rats had dissimilar faunal assemblages. This suggests that different indices for determining the postmortem submersion interval of corpses based on midge larvae colonization should be developed for these two habitats. This investigation does not provide replicated data, but does shed light on what may happen to mammalian carcasses placed in a stream at a particular time of the year.

Reproductive Function for a C-terminus Extended, Male-Transmitted Cytochrome C Oxidase Subunit II Protein Expressed in both Spermatozoa and Eggs

Our previous study documented expression of a male‐transmitted cytochrome c oxidase subunit II protein (MCOX2), with a C‐terminus extension (MCOX2e), in unionoidean bivalve testes and sperm mitochondria. Here, we present evidence demonstrating that MCOX2 is seasonally expressed in testis, with a peak shortly before fertilization that is independent of sperm density. MCOX2 is localized to the inner and outer sperm mitochondrial membranes and the MCOX2 antibodys epitope is conserved across >65 million years of evolution. We also demonstrate the presence of male‐transmitted mtDNA and season‐specific MCOX2 spatial variation in ovaries. We hypothesize that MCOX2 plays a role in reproduction through gamete maturation, fertilization and/or embryogenesis.

Maximizing collection and minimizing risk: does vacuum suction sampling increase the likelihood for misinterpretation of food web connections?

Molecular tools that characterize the structure of complex food webs and identify trophic connectedness in the field have become widely adopted in recent years. However, characterizing the intensity of predator–prey interactions can be prone to error. Maximizing collection success of small, fast‐moving predators with vacuum suction samplers has the potential to increase the likelihood of prey DNA detection either through surface‐level contamination with damaged prey or direct consumption within the sampling device. In this study, we used PCR to test the hypothesis that vacuum suction sampling will not cause an erroneous increase in the detection of ‘predation’, thereby incorrectly assigning trophic linkages when evaluating food web structure. We utilized general (1) Aphidoidea and (2) Collembola primers to measure the predation rates of Glenognatha foxi (Araneae: Tetragnathidae) on these prey collected by hand versus those sampled with a vacuum suction device. With both primer pairs, there was no significant increase in predators screening positive for prey DNA when sampled by vacuum suction versus those predators collected, in parallel, by hand. These results clearly validate the application of vacuum suction sampling during molecular gut‐content analysis of predator–prey feeding linkages in the field. Furthermore, we found no evidence that predation was occurring inside the suction sampler because specimens collected were never observed to be feeding nor did they screen positive at greater frequencies than hand‐collected individuals. Therefore, it can be concluded that the use of vacuum suction sampling devices (in this case a Modified CDC Backpack Aspirator Model 1412) is suitable for molecular gut‐content analysis.

Molecular diagnosis of a previously unreported predator–prey association in coffee: Karnyothrips flavipes Jones (Thysanoptera: Phlaeothripidae) predation on the coffee berry borer

The coffee berry borer, Hypothenemus hampei, is the most important pest of coffee throughout the world, causing losses estimated at US

Palaeoheterodont Phylogeny, Character Evolution, Diversity and Phylogenetic Classification: A Reflection on Methods of Analysis

500 million/year. The thrips Karnyothrips flavipes was observed for the first time feeding on immature stages of H. hampei in April 2008 from samples collected in the Kisii area of Western Kenya. Since the trophic interactions between H. hampei and K. flavipes are carried out entirely within the coffee berry, and because thrips feed by liquid ingestion, we used molecular gut-content analysis to confirm the potential role of K. flavipes as a predator of H. hampei in an organic coffee production system. Species-specific COI primers designed for H. hampei were shown to have a high degree of specificity for H. hampei DNA and did not produce any PCR product from DNA templates of the other insects associated with the coffee agroecosystems. In total, 3,327 K. flavipes emerged from 17,792 H. hampei-infested berries collected from the field between April and September 2008. Throughout the season, 8.3% of K. flavipes tested positive for H. hampei DNA, although at times this figure approached 50%. Prey availability was significantly correlated with prey consumption, thus indicating the potential impact on H. hampei populations.

Mitochondrial phylogenomics of Hemiptera reveals adaptive innovations driving the diversification of true bugs

ABSTRACT Graf and Cummings (2006), hereafter referred to simply as “G & C”, provided phylogenetic analyses of a three-partition data set in order to (1) examine the higher level evolutionary relationships within the Palaeoheterodonta, (2) estimate the history of character state change, and (3) develop a phylogenetic classification for the group. However, portions of the available COI DNA sequence data, for multiple terminals, were omitted from G & Cs phylogenetic analyses, and no attempt was made to explicitly account for the documented saturation in the COI data partition. In order to evaluate the effects of these omissions, we performed Bayesian inference (BI) as well as maximum parsimony (MP) analyses on G & Cs combined evidence (CE) matrix that included all of the ingroup COI sequences contained in G & C, plus the omitted outgroup COI sequences. We conclude that G & Cs COI DNA sequence omissions, when combined with MP analyses not accounting for COI saturation, negatively affected the topologies of the best trees obtained from phylogenetic analyses of the CE matrix. This conclusion questions the utility of G & Cs inferences regarding palaeoheterodont bivalve character evolution as well as the taxonomic classification drawn from its preferred topology. For example, counter to G & Cs inferences, our BI and “transformed COI” MP analyses determined that unionoid oyster conchology has evolved multiple times, and all of our phylogenetic analyses indicate that the Etheriidae (sensu G & C) is not monophyletic. However, it should be noted that, to date, no phylogenetic analysis of this data set has robustly estimated all basal nodes within the Unionoida. Therefore, any inferences regarding unionoid bivalve character evolution, diversity and classification drawn from these topologies should be considered weakly supported.

Identification of prey of Myotis septentrionalis using DNA-based techniques

Hemiptera, the largest non-holometabolous order of insects, represents approximately 7% of metazoan diversity. With extraordinary life histories and highly specialized morphological adaptations, hemipterans have exploited diverse habitats and food sources through approximately 300 Myr of evolution. To elucidate the phylogeny and evolutionary history of Hemiptera, we carried out the most comprehensive mitogenomics analysis on the richest taxon sampling to date covering all the suborders and infraorders, including 34 newly sequenced and 94 published mitogenomes. With optimized branch length and sequence heterogeneity, Bayesian analyses using a site-heterogeneous mixture model resolved the higher-level hemipteran phylogeny as (Sternorrhyncha, (Auchenorrhyncha, (Coleorrhyncha, Heteroptera))). Ancestral character state reconstruction and divergence time estimation suggest that the success of true bugs (Heteroptera) is probably due to angiosperm coevolution, but key adaptive innovations (e.g. prognathous mouthpart, predatory behaviour, and haemelytron) facilitated multiple independent shifts among diverse feeding habits and multiple independent colonizations of aquatic habitats.

Parallel evolution of larval morphology and habitat in the snail-killing fly genus Tetanocera.

Abstract Identifying and characterizing trophic linkages is fundamental to understanding how prey availability affects predator behavior, distribution, and density, and to elucidating the extent to which predators regulate prey populations. Vertebrate insectivores, such as bats, are a pervasive top-down force on insect populations in forest ecosystems. Bats are predators sensitive to habitat perturbations, whose prey selection behavior warrants further study. We identified trophic connections between a forest bat (Myotis septentrionalis) and its prey by isolating and sequencing cytochrome c oxidase subunit I gene (COI) fragments of insect prey obtained from bat fecal samples. Prey identities were inferred using GenBank and the Barcode of Life Data System (BOLD). We also identified prey remains morphologically from the same fecal samples, allowing comparisons across novel (GenBank and BOLD) and traditional (morphological) techniques. Lepidopterans were the most frequently detected prey in all approaches. Detection of common insect orders varied across procedures (P < 0.001), suggesting methodological bias at coarse taxonomic resolutions. Of the DNA-based approaches, GenBank provided the more diverse assessment of prey. We reveal trophic linkages for northern bats by identifying 20 prey genera and species using BOLD, more than one-half of which were smaller lepidopterans. The disproportionate number of smaller lepidopteran prey (mean [±SE] wingspan 24.2 ± 2.05 mm) exceeded expectations based on field-based assessments. M. septentrionalis is known to use both aerial-hawking and gleaning behaviors. Lepidopteran prey consumed by M. septentrionalis were smaller than reported for conspecfic genera, suggesting this species differentiates itself from sympatric insectivorous bats with the prey it selects.

A molecular phylogeny of the checkered beetles and a description of Epiclininae a new subfamily (Coleoptera: Cleroidea: Cleridae)

In this study, we sequenced one nuclear and three mitochondrial DNA loci to construct a robust estimate of phylogeny for all available species of Tetanocera. Character optimizations suggested that aquatic habitat was the ancestral condition for Tetanocera larvae, and that there were at least three parallel transitions to terrestrial habitat, with one reversal. Maximum likelihood analyses of character state transformations showed significant correlations between habitat transitions and changes in four larval morphological characteristics (cuticular pigmentation and three characters associated with the posterior spiracular disc). We provide evidence that phylogenetic niche conservatism has been responsible for the maintenance of aquatic‐associated larval morphological character states, and that concerted convergence and/or gene linkage was responsible for parallel morphological changes that were derived in conjunction with habitat transitions. These habitat–morphology associations were consistent with the action of natural selection in facilitating the morphological changes that occurred during parallel aquatic to terrestrial habitat transitions in Tetanocera.