Molecular phylogeny of Harpactorinae and Bactrodinae uncovers complex evolution of sticky trap predation in assassin bugs (Heteroptera: Reduviidae)

Sticky trap predation, the use of adhesive substances to trap and capture prey, is an intriguing yet poorly studied predatory strategy. Unique among known sticky trap predators, assassin bugs (Reduviidae) have evolved both exogenous and endogenous sticky trap predatory mechanisms: some trap their prey with sticky plant resins, some scavenge insects entrapped by sticky plant trichomes and others self‐produce sticky secretions. The evolution of these different strategies in assassin bugs is poorly understood due to the lack of comprehensive phylogenies. We reconstruct a phylogeny of Reduviidae (141 taxa; > 5000 bp) focusing on the Harpactorinae and Bactrodinae that engage in sticky trap predation. Ancestral state reconstruction, and temporal and geographical divergence analyses show that sticky trap predation techniques in assassin bugs evolved at least seven times independently since the late Cretaceous: use of sticky plant trichomes evolved as many as four times, resin‐use twice independently and once as a transition from trichome use, and ‘self‐stickiness’ once. Exogenous and endogenous sticky traps first appeared in the Neotropics, with the two exogenous mechanisms (resin and trichome use) subsequently evolving independently in the Old World. This study illustrates, for the first time, the complex evolutionary pattern of sticky trap predation within assassin bugs.     

Redistribution of sediments in three Swedish lakes

Sedimentation and redistribution of fine sediments in three Swedish lakes of different character have been investigated using settling sediment traps. The bottom shear stress from wind generated waves are calculated and the extension of erodable bottom area is related to wind conditions. Wave induced erosion and deposition during and after cessation of storms in different parts of a lake are discussed theoretically. It is shown that a single one year storm may redistribute more bottom material than the accumulated resuspension caused by frequent but smaller wind events. The settling sediment trap deposition and the concentration of suspended solids are related to the extension of erodable bottom area of particular storms. It is found that in lakes where there are relatively large areas of erosion bottoms, resuspended material from the part of the lake most susceptible to strong winds of large fetch constitutes a major part of the settled material on deep bottoms.     

Methods to Reduce Avian Bycatch in Small Mammal Studies Using Snap Traps

ABSTRACT Avian bycatch, a common and undesired occurrence in small mammal studies, should be minimized by researchers. We examined effects of trap covering, treadle color (copper or yellow plastic), trap size (mouse or rat), and trap weathering (traps <1 yr or ≥ 1 yr old) on avian bycatch during 3 years. We found that covered traps caught 81% fewer birds and 70% fewer small mammals than did uncovered traps, that mouse traps caught 30% more birds and 38% more small mammals than did rat traps, and no capture differences for treadle color or trap weathering. Covered traps effectively reduced avian bycatch and should be used when reduced small-mammal capture rates are acceptable.     

The potential of flower odours for use in population monitoring of Western flower thrips Frankliniella occidentalis Perg. (Thysanoptera: Thripidae)

Sticky blue traps are a suitable and important tool for Western Flower Thrips population monitoring in greenhouses. They can be used in vegetables and in ornamentals, and provide important information on the current status of the pest population. However, such traps cannot be used in some susceptible plant species when they are flowering because at that stage the plants are more attractive to Western Flower Thrips than the traps. We therefore tried to increase trap attractiveness by combining the colour cue with an attractive odour cue. In laboratory experiments, we found a significant additive effect on attractiveness for two odours in traps provided with both the visual and the olfactory cues as compared to traps with either cue alone. However, these results could not easily be reproduced in greenhouses. The main factors responsible for this failure seem to be (1) the only moderate, additive increase of trap attractiveness when using combined visual and olfactory cues, and (2) the problems associated with odour diffusion. Unless a more attractive odour is found and a suitable odour dispenser is available, the use of odours to enhance sticky blue trap attractiveness for Western Flower Thrips cannot be recommended and, given the added cost for the trap, may not be affordable for growers.     

Protein-based phylogenies support a chimeric origin for the eukaryotic genome

The phylogenetic position of the archaebacteria and the place of eukaryotes in the history of life remain a question of debate. Recent studies based on some protein-sequence data have obtained unusual phylogenies for these organisms. We therefore collected the protein sequences that were available with representatives from each of the major forms of life: the gram-negative bacteria, gram-positive bacteria, archaebacteria, and eukaryotes. Monophyletic, unrooted phylogenies based on these sequence data show that seven of 24 proteins yield a significant gram-positive-archaebacteria clade/gram-negative- eukaryotic clade. The phylogenies for these seven proteins cannot be explained by the traditional three-way split of the eukaryotes, archaebacteria, and eubacteria. Nine of the 24 proteins yield the traditional gram-positive-gram-negative clade/archaebacteria-eukaryotic clade. The remaining eight proteins give phylogenies that cannot be statistically distinguished. These results support the hypothesis of a chimeric origin for the eukaryotic cell nucleus formed from the fusion of an archaebacteria and a gram-negative bacteria.      

An effective strategy for trapping Douglas-fir beetle, Dendroctonus pseudotsugae (Col., Scolytidae) using combinations of unbaited and pheromone baited funnel traps

Experiments were conducted to confirm and quantify earlier observations that unbaited funnel traps in conjunction with pheromone baited funnel traps may substantially increase trap catches of Douglas-fir beetles, Dendroctonus pseudotsugae . In 12 replicates of one of these experiments during 1998 and 1999, the catches of a single baited control trap were compared to those of a set of four traps where the central trap was baited and a ring of three traps, 1 m from the central trap arranged in a star configuration, were unbaited. In the second experiment conducted during 1999, a ring of three unbaited traps was placed at 2 m and a second at 5 m from the central baited trap. Statistically robust results demonstrated clearly that the configuration of one central baited trap plus three unbaited satellite traps collected twice as many beetles on average over the season compared to the baited control trap. Addition of a second ring of unbaited traps increased collections by only about 20%, but this experiment indicated that trap catches dropped off exponentially with distance from the centre. The number of beetles caught in the baited traps was essentially the same in all 3 arrangements, suggesting that the additional unbaited traps captured beetles that otherwise may not have been captured.     

Minimum conflict: a divide-and-conquer approach to phylogeny estimation.

MOTIVATION: Fast and reliable phylogeny estimation is rapidly gaining importance as more and more genomic sequence information is becoming available, and the study of the evolution of genes and genomes accelerates our understanding in biology and medicine alike. Branch attraction phenomena due to unequal amounts of evolutionary change in different parts of the phylogeny are one major problem for current methods, placing the species that evolved fast in one part of the phylogenetic tree, and the species that evolved slowly in the other. RESULTS: We describe a way to avoid the artifactual attraction of species that evolved slowly, by detecting shared old character states using a calibrated comparison with an outgroup. The corresponding focus on shared novel character states yields a fast and transparent phylogeny estimation algorithm, by application of the divide-and-conquer principle, and heuristic search: shared novelties give evidence of the exclusive common heritage (monophyly) of a subset of the species. They indicate conflict in a split of all species considered, if the split tears them apart. Only the split at the root of the phylogenetic tree cannot have such conflict. Therefore, we can work top-down, from the root to the leaves, by heuristically searching for a minimum-conflict split, and tackling the resulting two subsets in the same way. The algorithm, called "minimum conflict phylogeny estimation" (MCOPE), has been validated successfully using both natural and artificial data. In particular, we reanalyze published trees, yielding more plausible phylogenies, and we analyze small "undisputed" trees on the basis of alignments considering structural homology. AVAILABILITY: MCOPEis available via http://bibiserv.techfak.uni-bielefeld.de/mcope/. CONTACT: fuellen@alum.mit.edu     

CLADISTIC INFERENCE AND EVOLUTIONARY SCENARIOS: LOCOMOTORY STRUCTURE, FUNCTION, AND PERFORMANCE IN WATER STRIDERS

Abstract — A research methodology that aims to reveal how historical changes in environmental conditions (or selective regimes) have shaped the adaptive evolution of clades is applied to the adaptive evolution of water striders and their allies (Hemiptera-Heteroptera, Gerromorpha), a group of semiaquatic insects which includes species that are conspicuously adapted to life on the surface film of water. Based upon reconstructed phylogenies for the higher gerromorphan taxa, the hypothesis that the hygropetric zone is the ancestral one is confirmed for the Mesoveliidae, Hebridae and the clade comprising the Paraphrynoveliidae, Macroveliidae and Hydrometridae, but not for the Hermatobatidae and Veliidae. There is no support for the hypothesis that the intersection zone was a sort of transitional zone during the ecological evolution of pleustonic bugs. It is shown that the unique morphological and behavioural traits of the most derived members of this group evolved after inferred historical changes in environmental conditions and therefore qualify as adaptations in the sense of Gould and Vrba (1982) , Coddington (1988) and Baum and Larson (1991) . Other predictions about the adaptive evolution of gerromorphan bugs do not pass the cladistic test. The study illustrates that cladistic inference is a valuable tool in clarifying and sharpening retrospective explanations of complex evolutionary scenarios.     

Enhanced gene trapping in mouse embryonic stem cells

Gene trapping is used to introduce insertional mutations into genes of mouse embryonic stem cells (ESCs). It is performed with gene trap vectors that simultaneously mutate and report the expression of the endogenous gene at the site of insertion and provide a DNA tag for rapid identification of the disrupted gene. Gene traps have been employed worldwide to assemble libraries of mouse ESC lines harboring mutations in single genes, which can be used to make mutant mice. However, most of the employed gene trap vectors require gene expression for reporting a gene trap event and therefore genes that are poorly expressed may be under-represented in the existing libraries. To address this problem, we have developed a novel class of gene trap vectors that can induce gene expression at insertion sites, thereby bypassing the problem of intrinsic poor expression. We show here that the insertion of the osteopontin enhancer into several conventional gene trap vectors significantly increases the gene trapping efficiency in high-throughput screens and facilitates the recovery of poorly expressed genes.     

A poor international standard for trap selectivity threatens carnivore conservation

Unintentional mortality of endangered carnivores due to non-selective trapping is important for conservation and warrants urgent attention. Currently, non-selective traps are being approved and used based on trap selectivity tests conducted according to International Organization for Standardization (ISO) guidelines. We review these guidelines and find them inadequate, because: (1) the ISO definition of selectivity does not account for relative abundance of target and non-target species and does not therefore meaningfully reflect selectivity; (2) the guidelines methodology at best quantifies relative selectivity of one trap against another, which is of limited use unless the control trap is known to have an acceptable level of absolute selectivity for the target species; (3) information on relative trap selectivity cannot simply be extrapolated elsewhere, unless species assemblage and relative species abundances are consistent. We demonstrate that the ISO definition of trap selectivity is only a simple capture proportion and therefore does not represent trap selectivity. ISO guidelines on trap selectivity should be reviewed to reflect particular ecological scenarios and we suggest how this might be done. Policy-makers, practitioners and researchers should interpret scientific results more cautiously. Trap approval decisions should be based on scientific evidence to avoid undermining the conservation of biodiversity.     

Why Are Some Evolutionary Trees in Natural History Museums Prone to Being Misinterpreted?

Today, the picture of an evolutionary tree is a very well-known visual image. It is almost impossible to think of the ancestry and relationships of living beings without it. As natural history museums play a major role in the public understanding of evolution, they often present a wide variety of evolutionary trees. However, many studies have shown (Baum and Offner 2008; Baum et al. 2005; Catley and Novick 2008; Evans 2009; Gregory 2008; Matuk 2007; Meir et al. 2007b; Padian 2008) that even though evolutionary trees have the potential to engage visitors of natural history museums with the phenomena of evolution, many of them unwittingly might lead to misunderstandings about the process. As valuable research and educational institutions, one of the museum’s important missions should be the careful design of their exhibits on evolution considering, for example, common preconceptions visitors often bring, such as the notion that evolution is oriented from simple toward complex organisms (incarnating the idea of a single ladder of life amidst the extraordinary diversity of organisms) and that humans are at the pinnacle of the evolutionary story, as well as na?ve interpretations of phylogenies. Our aim in this article is to show from history where many of these misunderstandings come from and to determine whether five important Western natural history museums inadvertently present “problematic” evolutionary trees (which might lead to non-scientific notions).     

Optimum spacing of pheromone traps for monitoring the coffee leaf miner Leucoptera coffeella

Pest monitoring with pheromone traps is affected mainly by factors such as trap placement and pest biology. The intertrap distance can affect the capture due to competition among traps that are placed at short distances. We studied the interference among pheromone traps used to monitor males of the coffee leaf miner, Leucoptera coffeella (Guérin‐Méneville) (Lepidoptera: Lyonetiidae), with traps placed at various distances. Using geostatistical analysis, we determined at what distance captures were independent from other traps. Traps were placed in groups of 12 with distances among traps per group either 2, 5, 10, 15, or 30 m. Traps were checked for males every 4 days during 16 days. We found interference between traps when intertrap distances were shorter than 10 m. The range and magnitude of spatial dependence varied considerably among each sampling date and wind direction. For directions of 45° and 135°, the traps should be placed 110 and 177 m apart, respectively, to obtain spatially independent counts and therefore representative samplings for assessing the insect population in the area. These results have implications for developing sampling plans for managing L. coffeella with pheromone traps; the spatial analysis indicated that a trap density of one pheromone trap for every 3.5–4 ha would be adequate for the monitoring of the coffee leaf miner.     

Best Management Practices for Trapping Furbearers in the United States

Humans have used wild furbearers for various purposes for thousands of years. Today, furbearers are sustainably used by the public for their pelts, leather, bones, glands, meat, or other purposes. In North America, contemporary harvest of furbearers has evolved along with trap technologies and societal concerns, and is now highly regulated and more closely coupled with harvest analysis and population monitoring. Traps and regulated trapping programs provide personal or cultural rewards that can also support conservation, and can assist with advancing ecological knowledge through research, protecting endangered species, restoring populations or habitats, protecting personal property, and enhancing public health and safety. However, animal welfare and trap selectivity remain important topics for furbearer management in North America, as they have for more than a century. A related international challenge to modern furbearer management came with the Wild Fur Regulation by the European Union, which passed in 1991. This regulation prohibited use of foothold traps in many European countries and the importation of furs and manufactured fur products to Europe from countries that allowed use of foothold traps or trapping methods that did not meet internationally agreed-upon humane trapping standards. To address existing national concerns and requirements of the Wild Fur Regulation, the United States and European Union signed a non-binding bilateral understanding that included a commitment by the United States to evaluate trap performance and advance the use of improved traps through development of best management practices (BMPs) for trapping. Our testing followed internationally accepted restraining-trap standards for quantifying injuries and capture efficiency, and we established BMP pass-fail thresholds for these metrics. We also quantified furbearer selectivity, and qualitatively assessed practicality and user safety for each trap, yielding overall species-specific performance profiles for individual trap models. We present performance data for 84 models of restraining traps (6 cage traps, 68 foothold traps, 9 foot-encapsulating traps, and 1 power-activated footsnare) on 19 furbearing species, or 231 trap-species combinations. We conducted post-mortem examinations on 8,566 furbearers captured by trappers. Of the 231 trap model-species combinations tested, we had sufficient data to evaluate 173 combinations, of which about 59% met all BMP criteria. Pooling species, cage traps produced the lowest average injury score (common injuries included tooth breakage), with minimal differences across other trap types; species-specific patterns were generally similar, with the exception of raccoons (Procyon lotor) for which foot-encapsulating traps performed better than other foot-restraining trap types. Padded-jaw foothold traps performed better than standard-jaw models for many species, though often similar to and occasionally worse than offset- or laminated-jaw models. Most traps we tested had high capture efficiency; only 5 (3%) failed BMP standards strictly because of poor efficiency. Average furbearer selectivity was high across all trap types we evaluated and was lowest for footsnares (88%) and highest for foot-encapsulating traps (99%). Mortality from trap-related injury in restraining traps we tested was very rare for furbearers (0.5% of animals). In over 230,000 trap-nights across a 21-year period, no individuals of a threatened or endangered species were captured. Of 9,589 total captures, 11% were non-furbearers, of which 83% were alive upon trap inspection; nearly all non-furbearer mortalities were birds, rabbits, or squirrels. Approximately 2% of total captures were feral or free-ranging dogs (Canis familiaris), of which none died or were deemed in need of veterinary care by either our technicians or the owners (if located). Similarly, 3% of total captures were feral or free-ranging cats (Felis catus); 2 were dead, and although locating potential owners was often impossible, none of the remaining cats were deemed in need of veterinary care by technicians or owners. Our results show that furbearer selectivity was high for all trap types evaluated, mortality or significant injury was very rare for domestic (or feral) animals, and the most potential for mortality or injury of non-furbearers was with smaller animals, a majority of which were squirrels and rabbits. Our results suggest that injury scores for a given trap-species combination are unlikely to vary significantly across states or regions of the United States, provided similar methods are employed. Our data also suggest that taxonomic affiliation and body-size groupings are correlated with injury scores, presumably through morphological, physiological, or behavioral adaptations or responses that influence injury potential during restraint; higher injury scores in foot-restraining trap types were more likely in smaller or more dexterous species, whereas injury scores were typically lowest for the felids we evaluated. For some species (e.g., American badger [Taxidea taxus], bobcat [Lynx rufus]), most restraining traps we tested met BMP standards, whereas few restraining traps we tested met standards for other species (e.g., muskrat [Ondatra zibethicus], striped skunk [Mephitis mephitis]). Comparison of our results with survey information collected during 2015 on trap use in the United States indicates that approximately 75% of all target furbearers harvested were taken in BMP-compliant traps, with another 10% taken in traps yet to be tested on that species. Future trap testing and development should focus on commonly used traps not yet tested on a species, species for which few passing traps currently pass BMP criteria, and trap models and modifications most likely to minimize trap injuries given a species morphology, physiology, and behavior. Outreach efforts should focus on general BMP awareness, discouraging use of traps that fail BMP standards for a given species, and public outreach on trapping. Restraining (and other) traps have evolved substantially in recent decades and offer numerous benefits to individuals, conservation, and society. However, continuing to address societal concerns remains a critical component of modern regulated trapping and furbearer management. Published trapping BMPs are regularly updated online and may include additional approved restraining and killing traps that were evaluated as part of testing by Canada. We will periodically update the trap performance tables and figures we presented and make them available online at the Association of Fish and Wildlife Agencies website. Published 2020. This article is a U.S. Government work and is in the public domain in the USA. Wildlife Monographs published by Wiley Periodicals LLC on behalf of The Wildlife Society.     

STATISTICAL TESTS OF HOST-PARASITE COSPECIATION

A history of cospeciation (synchronous speciation) among ecologically associated, but otherwise distantly related, species is often revealed by a strong correspondence of their phylogenies. In this paper, we present several tests of cospeciation that use maximum-likelihood and Bayesian methods of phylogenetic estimation. The hypotheses tested include: (1) topological agreement of phylogenies for coevolving groups; (2) identical speciation times of associated species; and (3) identical evolutionary rates in genes of associated species. These tests are applied to examine a possible instance of host-parasite coevolution among pocket gophers and lice using mitochondrial COI DNA sequences. The observed differences between gopher and louse trees cannot be explained by sampling error and are consistent with a rate of host switching about one-third the host speciation rate. A subset of the gopher-louse data is consistent with a common history of evolution (i.e., the topologies and speciation times are identical). However, the relative rate of nucleotide substitution is two to four times higher in the lice than in the gophers.     

An optimized hair trap for non-invasive genetic studies of small cryptic mammals

As sample quality and quantity is a crucial factor in non-invasive genetics, we focused on the improvement of sampling efficiency of glue hair traps. We invented an optimized hair trap with moveable parts which enhanced sampling of high-quality genetic material. With the aid of the optimized hair trap, we were able to remotely pluck a sufficient amount of hair bulbs from our study animal the common hamster (Cricetus cricetus) with a trapping success of 49.3% after one survey night. The number of collected hairs with bulbs ranged between 1 and 50, with an average of 20.7 ± 14.8. Subsequently, the use of the hair trap in combination with a simplified laboratory routine allowed us to amplify species-specific microsatellites with an amplification success of 96.2% and ADO of 4.6%. This optimized trap may find usage for species identification or could be used as an instrument for long-term genetic monitoring of mammal populations.     

THE COMPARISON OF YELLOW CYLINDRICAL, FLAT AND WATER TRAPS, AND OF JOHNSON SUCTION TRAPS, FOR SAMPLING APHIDS

Different traps were compared to find the type most suitable for studying aphid vectors of plant viruses quantitatively.
A Moericke water trap caught more aphids than a flat sticky trap of equal area. A flat sticky trap (930 sq. cm.) caught half as many aphids as a cylindrical trap (945 sq. cm.), which caught about one-third as many as a water trap (1200 sq. cm.) or a Johnson suction trap (9 in. fan) when operated at between 2 and 3 ft. over bare soil.
Yellow traps caught proportionally more Tuberculoides annulatus , and in summer more Capitophorus species than a suction trap, but significantly fewer Anoecia corni, Sitobium spp. and Pemphigus bursarius. Traps with a level surface caught proportionally more Brevicoryne brassicae, Aphis fabae and Myzus persicae , but fewer Anoecia corni and Drepanosiphum plantanoides than vertical cylindical traps. Attraction by colour influences the catch on horizontal traps more than on cylindrical traps because there is less impaction by the wind.
Only suction traps indicate the number of aphids per unit volume of air and are non-selective, but they are expensive and require an electric power supply. Water traps effectively catch those aphids that are attracted to yellow, but they require frequent attention. Sticky traps catch fewer aphids than either suction or water traps, but they can be left unattended for about 2 weeks. Flat sticky traps catch aphids likely to land on a crop, and cylindrical traps show when aphids are in the air, but not if those aphids are able or wanting to land. For routine work cylindrical sticky traps have other advantages; they are cheap and do not require skilled handling, and their catches of alate Myzus persicae have been correlated with the spread of some plant viruses.     

Comparison of several traps for catching German cockroaches (Dictyoptera: Blattellidae) under laboratory conditions

German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae), catch by five types of traps and modifications of each, were tested under controlled laboratory conditions. Cockroach catch differed significantly among traps. Lo-line trap caught the greatest number of cockroaches in the test arena for each size class (23% small nymphs, 39% of gravid females, and 60% of other size classes in the experimental arena). Jar traps caught the least number of cockroaches in the test arena for each size class (range, 7-23% of each size class trapped). Modifications of traps also altered catch of cockroaches. Food bait tablets increased catch significantly; however, increases were small (<10%). Size of traps did not affect catch; whole traps or half traps caught the same number of cockroaches. Jar traps were much less effective than sticky traps, catching only half the number of cockroaches as sticky traps. A thin layer of petrolatum was a more effective barrier in jar traps to cockroach escape than powdered Olancha clay. Traps with petrolatum caught about twice as many cockroaches as traps with clay. Trapping of any of six life stages was not significantly affected by catch of any of the other stages. Rather, trap catch of each life stage was dependent on the number of that life stage available in the experimental arenas. In conclusion, of the traps tested, the Lo-line trap was the most sensitive for measuring cockroach catch, whereas the Detector trap (one third of trap) was the most economical trap (greatest sensitivity for lowest cost).     

Mechanical performance of rat, mouse and mole spring traps, and possible implications for welfare performance

Lethal spring traps are widely used for killing small mammals in the UK. Many require government approval, based primarily on humaneness. However, mole traps and break-back traps for rats and mice are exempt; those available vary widely in price and apparent quality. The EU is considering implementing a Trapping Directive that would alter UK legislation, and a recent report advised the EU that trapping legislation should cover all trapped species and encourage improvement of traps. Mechanical trap performance is often used as an indicator of welfare impact. We examined the mechanical evidence for scope to improve the welfare standards of rat, mouse and mole spring traps. We measured mechanical performance among a range of rat, mouse and mole traps. Impact momentum values varied 6-8 fold, and clamping force values 4-5.5 fold, among traps for killing each species. There was considerable overlap in the performance of rat and mouse traps. Trap-opening angle and spring type were related to impact momentum and clamping force in traps for both species. There was no relationship between price and mechanical performance in traps for any species, except talpa mole traps. We are unable to judge the direct welfare impact of the traps tested, but rather the potential welfare threat associated with their exemption from approval. The wide variation in mechanical performance in traps for each species, overlap in performance between rat and mouse traps and increasing availability of weaker plastic rodent traps indicate considerable scope for improving the humaneness of spring traps for rats, mice and moles. We conclude that all such traps should be subject to the UK approval process. New welfare categories might improve trap standards further. Our results could also help improve rodent trap design and assist consumers in selecting more powerful traps. Many thousands of rats, mice and moles might benefit.     

The likelihood node density effect and consequences for evolutionary studies of molecular rates

Many molecular phylogenies show longer root-to-tip path lengths in species-rich groups, encouraging hypotheses linking cladogenesis with accelerated molecular evolution. However, the pattern can also be caused by an artifact called the node density effect (NDE): this effect occurs when the method used to reconstruct a tree underestimates multiple hits that would have been revealed by extra nodes, leading to longer root-to-tip path lengths in clades with more terminal taxa. Here we use a twofold approach to demonstrate that maximum likelihood and Bayesian methods also suffer from the NDE known to affect parsimony. First, simulations deliberately mismatching the simulation and reconstruction models show that the greater the model disparity, the greater the gap between actual and reconstructed tree lengths, and the greater the NDE. Second, taxon sampling manipulation with empirical data shows that NDE can still be present when using optimized models: across 12 datasets, 70 out of 109 sister path comparisons showed significant evidence of NDE. Unless the model fairly accurately reconstructs the real tree length-and given the complexity of real sequence evolution this may be uncommon -- it will consistently produce a node density artifact. At commonly encountered divergence levels, a 10% underestimation of tree length results in > or = 80% of simulated phylogenies showing a positive NDE. Bayesian trees have a slight but consistently stronger effect. This pervasive methodological artifact increases apparent rate heterogeneity, and can compromise investigations of factors influencing molecular evolutionary rate that use path lengths in topologically asymmetric trees.