Eastern North American Research Articles

Occupancy–detection models with museum specimen data: Promise and pitfalls

Abstract Historical museum records provide potentially useful data for identifying drivers of change in species occupancy. However, because museum records are typically obtained via many collection methods, methodological developments are needed to enable robust inferences. Occupancy–detection models, a relatively new and powerful suite of statistical methods, are a potentially promising avenue because they can account for changes in collection effort through space and time. We use simulated datasets to identify how and when patterns in data and/or modelling decisions can bias inference. We focus primarily on the consequences of contrasting methodological approaches for dealing with species' ranges and inferring species' non‐detections in both space and time. We find that not all datasets are suitable for occupancy–detection analysis but, under the right conditions (namely, datasets that are broken into more time periods for occupancy inference and that contain a high fraction of community‐wide collections, or collection events that focus on communities of organisms), models can accurately estimate trends. Finally, we present a case study on eastern North American odonates where we calculate long‐term trends of occupancy using our most robust workflow. These results indicate that occupancy–detection models are a suitable framework for some research cases and expand the suite of available tools for macroecological analysis available to researchers, especially where structured datasets are unavailable.

Last interglacial lake sediments preserved beneath Laurentide and Greenland Ice sheets provide insights into Arctic climate amplification and constrain 130 ka of ice‐sheet history

AbstractSediment cores from 13 lakes in a 1500 km transect along the eastern North American Arctic contain up to four superposed stratified interglacial units. All 13 lakes contain one unit with sediment similar in character and mass to Holocene gyttja, with 14C ages >40 ka, luminescence ages 90 to 120 ka, and pollen assemblages that require nearly complete Laurentide deglaciation, supporting a Last Interglacial (LIG; MIS 5e) age. Two lakes preserve an older interglacial, with luminescence ages suggesting an MIS 7 age. Four adjacent lakes record a thin, stratified organic unit between the LIG and Holocene units with 14C ages >50 ka, that is probably from late in MIS 5. Temperature estimates from biotic proxies suggest LIG summer temperatures 4–6°C above mid‐20th century values; pollen, chironomids and DNA document a poleward expansion of woody plants and invertebrate species during the LIG, supporting arguments that positive feedbacks native to the Arctic amplified insolation‐driven summer temperature increases. The stratigraphic succession implies the Laurentide Ice Sheet remained intact with sea level below ‐40 m from ~115 ka to ~11 ka, and places new constraints on the interpretation of cosmogenic radionuclide inventories in erratic boulders older than the Holocene throughout this region.

Deer browsing and light availability limit post oak (Quercus stellata) sapling growth and post-fire recovery in a xeric woodland

Historically, oaks dominated the canopies of large regions of eastern North American forests, but at many sites current recruitment is insufficient to sustain oak dominance. Intense browsing by white-tailed deer (Odocoileus virginianus) and light limitation due to expansion by fire-intolerant tree species may cause poor oak recruitment. In a xeric woodland in Kansas USA, we used a deer exclusion experiment in natural canopy gaps to quantify effects of browsing and light availability on post oak (Quercus stellata) sapling performance, meaning growth and survival. Two weeks after beginning the experiment, a prescribed fire occurred that, due to natural burn heterogeneity, affected 29 of 31 experimental canopy gaps and top-killed 78.6% of experimental saplings. This allowed us to examine post-fire recovery in a sub-set of saplings. Our hypotheses were 1) ambient deer browsing intensity reduces post oak sapling performance, 2) sapling performance increases with gap size and light availability, 3) deer browsing effects on sapling performance vary with light availability, and 4) re-growth rate of saplings that were top-killed by fire is affected by light, deer browsing and the interaction of light and browsing. After five years, deer exclusion increased sapling growth in height and aboveground biomass. Sapling height growth was positively correlated with light. Deer effects on sapling performance generally were consistent across light environments. However, there was a weak pattern toward more negative effects of browsing in high light than in low light environments for saplings that re-sprouted post-fire. Protection from deer shortened the time required for saplings to re-attain their pre-fire height from five to three years. We conclude that deer browsing reduces post oak recruitment in canopy gaps in these xeric woodlands. Further, under current browsing intensity, fire return intervals less than five years will strongly limit oak recruitment.

Effects of whole-tree and stem-only clearcutting on forest floor and soil carbon and nutrients in a balsam fir (Abies balsamea (L.) Mill.) and red spruce (Picea rubens Sarg.) dominated ecosystem

Intensive harvesting of forest biomass for bioenergy has the potential to degrade forest soils and productivity if ecosystem carbon and other nutrients are depleted faster than replenished naturally or by management inputs. Climate change mitigation potential associated with bioenergy may be threatened if forest management operations reduce soil carbon stocks. Research reported here was initiated in 1979 to determine the effects of whole-tree harvesting on long-term site productivity and ecosystem carbon and nutrient pools and fluxes in a northeastern North American temperate balsam fir-red spruce forest. A sequence of harvesting and silvicultural treatments were applied from 1981 to 1993 using a paired-watershed experimental design. Treatments included whole-tree clearcutting, stem-only harvesting, simulated by return of chipped or lopped delimbing residue, conifer release by applying herbicide, and pre-commercial thinning and fertilizer application. Quantitative samples of the forest floor were excavated in 2016. Quantitative soil pits were sampled in 2017 to a depth of 50 cm below the forest floor, where possible; the basal till subsoil was sampled to a depth of 100 cm with an auger. Forest floor samples were analyzed for total carbon, nitrogen, phosphorus, potassium, calcium, magnesium and aluminum. Organic and mineral soil layer samples from the quantitative pits were analyzed for pH, short and long-lived soil carbon via 13C cross polarization magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR), total carbon and nitrogen and extractable phosphorus, potassium, calcium, magnesium and aluminum. Forest floor carbon and nitrogen on whole-tree harvested plots 35 years after harvest were about 50% of the amount on the unharvested watershed. Stem-only harvesting partially mitigated the reduction, and gross losses were apparently offset by increases in the mineral soil solum to depth 50 cm, suggesting that downward translocation of soil organic matter was a significant ecosystem process during the 35 years since harvest. Accumulated forest floor and mineral soil stock of total carbon and nitrogen and extractable nutrients to depth 100 cm did not differ significantly between the harvested and unharvested watershed. A corresponding similarity in mineral soil pools of extractable phosphorus and non-acid cations in the two watersheds suggests that inputs from atmospheric deposition, primary and secondary mineral weathering, organic matter mineralization and litterfall balanced exports including leaching and plant uptake. Ecosystem stocks of extractable phosphorus, base cations, and total organic carbon and nitrogen were maintained 35 years after whole-tree harvesting of a primary spruce-fir forest.

A new look at the potential role of marine plastic debris as a global vector of toxic benthic algae

Marine plastic debris provides a significant surface area for potential colonization by planktonic and benthic harmful microalgae and for the adsorption of their toxins. Furthermore, floating plastics may substantially expand the substrate area available for benthic algae in the ocean, intensifying the transfer of potent toxins through pelagic food webs. In this study, we quantify the available surface area of micro- and macroplastics in different oceanic regions and assess the potential role of floating plastics as vectors for the transfer of toxins from three widespread benthic dinoflagellates, Gambierdiscus spp., Ostreopsis cf. ovata and Prorocentrum lima. To avoid bias associated to the occurrence of benthic algae in deep waters, we selected only records from 0 to 100 m depths. We estimate that 26.8 × 1010 cm2 of plastic surface area is potentially available in surface waters of the global ocean, mostly in the size range of large microplastics (1.01–4.75 mm). Based on the distribution of floating plastics and the habitat suitability of the selected microalgal species, the plastic relative colonization risks will be greater in the Mediterranean Sea and in the subtropical and temperate western margins of the oceans, such as the North American and Asian eastern coasts and, to a lesser extent, southern Brazil and Australia. In places where the colonization of O. cf. ovata cells on floating plastic debris has been properly quantified, such as the Mediterranean and southern Brazil, we estimate a colonization potential of up to 2 × 106 cells km−2 of ocean surface during the regular occurrence period and up to 1.7 × 108 cells km−2 during massive blooms of this species. As plastic pollution and harmful benthic algal blooms have both increased substantially over the past decades, we suggest that their interactive effects can become a major and novel threat to marine ecosystems and human health.

Phylogenetic community structure and stable isotope analysis of the parasitoid community associated with Eastern spruce budworm,Choristoneura fumiferana(Lepidoptera: Tortricidae)

AbstractEastern spruce budworm,Choristoneura fumiferanaClemens (Lepidoptera: Tortricidae), is a major pest of eastern North American forests. Outbreaks of spruce budworm occur every 30–40 years, causing high tree mortality.Researchers have established that higher proportions of hardwood trees within stands (higher hardwood content) may reduce the defoliation and mortality of balsam fir and spruces during spruce budworm outbreaks. One mechanism posited to explain these patterns is that hardwood trees positively impact the parasitoids of spruce budworm. Indeed, parasitism of spruce budworm by parasitoids has been found to be impacted by hardwood content. However, more research is needed to understand how hardwood content impacts the parasitoid community as a whole.In this study, we trialled the use of two analyses, phylogenetic community structure and stable isotope analysis, to examine how hardwood content influenced the parasitoid community associated with spruce budworm.We found that phylogenetic community structure differed between forest stands with different hardwood content. Furthermore, the trophic relationships between several parasitoids and caterpillars on balsam fir or hardwood trees changed within and between years.Our study highlights the potential of these two analyses for understanding how hardwood content influences the parasitoid community associated with spruce budworm.

Notes on Eastern North American Lepidoptera.

Notes on Eastern North American Lepidoptera.

Climatic niche comparisons of eastern North American and eastern Asian disjunct plant genera

AbstractAimWhile the floras of eastern Asia (EA) and eastern North America (ENA) share numerous genera, they have drastically different species richness. Despite an overall similarity in the quality of their temperate climates, the climate of EA is more spatially heterogeneous than that of ENA. Spatial environmental heterogeneity has been found to play a key role in influencing species richness in some regions. Here, we tested the following hypotheses: (a) EA species will occupy larger climatic niches than their ENA congeners, (b) congeners of EA‐ENA disjunct genera will occupy statistically equivalent climatic niches, and (c) congeners of EA‐ENA disjunct genera will occupy more similar climatic niches than expected by their respective physiographic context.LocationNorth America and Asia.Time periodPresent.Major taxa studiedSeed plants.MethodsPredictions generated by ecological niche models (ENMs) were compared for 88 species across 31 EA‐ENA disjunct genera. ENM predictions were assessed for geographic and ecological breadth. Tests for niche equivalency and similarity were performed for congeneric species pairs to determine if species of disjunct genera have experienced niche conservatism or divergence.ResultsEA species tend to occupy greater amounts of climatic niche space than their close relatives in ENA. Over two‐thirds of the conducted niche comparisons show that EA‐ENA congeners either occupy equivalent climatic niche space within these broader climatic regimes or occupy non‐equivalent niches that are as similar as expected given their physiographic contexts.Main conclusionsEA species tend to occupy larger climatic niches, and congeners of EA‐ENA disjunct genera tend to occupy equivalent/similar niche space within their respective distributions, with differences in occupied niches possibly due to their respective physiographic contexts, highlighting how niche‐neutral processes and niche conservatism may affect the distributions of disjunct species.

Mineral inputs, paleoecological change, and Holocene carbon accumulation at a boreal peatland in the Hudson Bay Lowlands, Canada

The Hudson Bay Lowlands (HBL) is a vast contiguous peatland extending over >370,000 km2 in Canada's boreal-subarctic, and is the traditional land of the Omushkego Cree. It is currently undergoing climatic warming alongside other anthropogenic stressors, and contains a large below-ground carbon pool. Understanding how climate variability and multiple stressors impact peat accumulation in this region is critical to discerning how northern peatlands will respond to future climate and land-use changes. Pollen- and macrofossil-based paleoecological reconstructions, and analyses of aluminum (Al) and titanium (Ti) fluxes in a Holocene-aged peat core (VM375) taken from a bog in the Attawapiskat watershed were conducted to link ecosystem changes with hydroclimate and long-term carbon storage. Peat initiation is dated to 5780 cal yr B.P., coincident with land emergence driven by glacial isostatic adjustment. From 4500 to 4200 cal yr B.P., apparent rate of carbon accumulation increased, and was linked to more rapid rates of peat accretion and increases in minerotrophic indicators in the pollen record. This increase in peat accretion and shift in vegetation composition co-occur with higher rates of mineral influx as shown by Ti and Al concentrations, which may have supplied nutrients. A fen to bog transition takes place ~3300 cal yr B.P., with increases in Sphagnum spores and macrofossils, and a decline in the apparent rate of carbon accumulation relative to the earlier half of the record, where paleoecological proxies indicate treed wetland and fen stages. Since peat inception, the total carbon stock of the 260-cm peat column is 110 kg C m−2. This multi-proxy record shows an association between changing peat types and variability in apparent rates of carbon accumulation, and supports the hypothesis that mineral nutrients either supplied by surface hydrology or by eolian deposition played a role in Holocene peat carbon accumulation in eastern North American boreal peatlands.

First report of halo blight of hop (Humulus lupulus) caused by Diaporthe humulicola in Quebec, Canada.

Halo blight of hop caused by Diaporthe humulicola has recently been reported in Michigan and Connecticut (Higgins et al. 2021, Allan-Perkins et al 2020). In August 2020 growers in Quebec, Canada reported necrotic foliar lesions and desiccation of the hop strobile (cone) on Chinook and Nugget cultivars. The foliar lesions were dry concentric circles with a chlorotic halo surrounding the lesions; no pycnidia were observed on leaves or cones. Up to 100% of the infected bract tissue was dry and easily shattered, the grower estimated that more than 90% of the plants in the hopyard exhibited symptoms. Twenty-six isolates were obtained from surface-sterilized leaf and cone tissue by plating the leading edge of lesions on potato dextrose agar. Fungal isolates were hyphal tipped and were incubated at 22°C with a 12 h photoperiod. After 21-days, all cultures were white to beige with pycnidia. DNA was extracted from cultures using the MagMAX Plant DNA Isolation Kit (Applied Biosystems, Foster City, CA). DNA amplification of a representative isolate (CD6C) was performed with primers ITS1/ITS4 (White et al. 1990) for the internal transcribed spacer (ITS), CYLH3F/H3-1b (Glass and Donaldson 1995) for histone 3 (HIS), and Ef1728f/EF1-986R (Carbone and Kohn 1999) for translation elongation factor 1-α (TEF). Amplification primers were used for bidirectional Sanger sequencing, reads were assembled using Geneious Prime (Biomatters, New Zealand), and identified using NCBI BLAST. BLAST results showed that the sequences for TEF, ITS, and HIS all had 100% pairwise identity to Diaporthe sp. 1-MI (MT909101, MT909099, MT909093, OK001342, MZ934713, OK001341). Futhermore, BLAST results showed that ITS and HIS have 100% pairwise identity D. humulicola (MN152929, MN180214). The TEF sequence also had 99.7% pairwise identity to D. humulicola (MN180209). Koch's postulates were conducted by inoculating six 3-mo-old 'Chinook' plants with conidia harvested from 28-day-old cultures and spraying 50 ml of inoculum (6 x 105 conidia/ml) or water to each plant. Plants were then stored in a greenhouse at 100% relative humidity at 22°C with a 14-h photo period. Lesions appeared on the adaxial side of the leaf after 21 days. D. humulicola was re-isolated from all infected leaf tissue, but not from any water inoculated plants and identified by conidial morphology using descriptions from Higgins et al. (2021). So far, Diaporthe sp. 1-MI appears to be synonymous with Diaporthe humulicola, but currently two names are being utilized (i.e. Diaporthe leaf spot and halo blight). In Higgins et al., (2021) it was proposed that the name halo blight might be more appropriate because disease symptoms are not confined to the leaves and cause significant blighting of cones. Halo blight caused by D. humulicola appears widespread in Michigan and Canada and may become an issue in other eastern North American growing regions with humid conditions.

Pace of passive margin tectonism revealed by U-Pb dating of fracture-filling calcite

A growing body of evidence demonstrates that Atlantic-style passive margins have experienced episodes of uplift and volcanism in response to changes in mantle circulation long after cessation of rifting. Passive margins are thus an attractive archive from which to retrieve records of mantle circulation and lithospheric alteration. However, this archive remains under-utilized due to difficulty in deciphering the surficial records of passive margin tectonism and linking them to seismic velocity structure. Here we present a new approach to unraveling the tectonic history of passive margins using U-Pb dating of calcite in faults and fractures along the eastern North American margin. These ages show a 40 Myr long period of continuous fracturing and faulting from ~115 to 75 Ma followed by another episode in Mio-Pliocene time. We argue that the former event represents a response to Cretaceous lithospheric alteration whereas the latter records development of modern relief in the northern Appalachians.

Integrating historical observations alters projections of eastern North American spruce–fir habitat under climate change

AbstractSpruce–fir (Picea–Abies) forests of the North American Acadian Forest Region are at risk of disappearing from the northeastern United States and Canada due to climate change. Species distribution models (SDMs) have been used to predict changes in this critical transitional ecosystem in the past, but none have addressed how seasonal patterns of temperature and precipitation interact to influence tree species abundance. Inferences have also been limited by contemporary inventory data that could not fully characterize species ranges because they either, (1) only sampled species occurrence after large‐scale human disturbance and settlement, or (2) did not span critical geopolitical boundaries (e.g., the US–Canadian border) that intersect the focal species' range(s). Here, we built new SDM models to better assess the bioclimatic distribution of four spruce–fir species and to test the importance of seasonal climate interactions. We compiled an extensive database of tree occurrence and abundance from recent (~1955–2012) and historical time periods (1623–1869) to model current species distributions and to predict how these might change under future climate. We found that including historical tree data in our SDMs revealed previously unrecognized suitable habitat along the southern edge of species' contemporary ranges. Random forest models predicted occurrence with high accuracy (area under receiver operator curve >0.98), and the seasonal climate variables that emerged as most important for these cold‐adapted species all included interactions that reflected sensitivity to colder temperatures, and preferences for wet weather concentrated in the winter months. Under moderate climate warming (representative concentration pathway 6.0), the northeastern United States retained additional suitable habitat when historical data were included through 2060 for three of the four species: red spruce (Picea rubens), black spruce (Picea mariana), and balsam fir (Abies balsamea), while white spruce (Picea glauca) habitat contracted into Canada. In contrast, future predictions from models that used contemporary data alone forecast extirpation for all four species from the northeastern United States. Overall, these findings highlight that prediction of species ranges in transitional ecosystems that span geopolitical boundaries and gradients of intense land use are improved when historical data and seasonal climate interactions of both temperature and precipitation variables are incorporated.

Woody invaders are more highly colonized by arbuscular mycorrhizal fungi than congeneric native species.

Invasive species tend to possess acquisitive plant traits that support fast growth and strong competitive ability. However, the relevance of symbioses with arbuscular mycorrhizal fungi (AMF) to the fast growing, acquisitive strategy of invasive species is still unclear. We measured AMF colonization in roots of five congeneric pairs of invasive and native eastern North American woody species (10 species total; 4 lianas, 6 shrubs) that were grown in a monoculture common garden experiment in Syracuse, NY. We then examined the relationships of AMF colonization to above and belowground traits of these species. Total AMF colonization and arbuscule colonization were greater in invasive compared to native woody species, a pattern that was more distinct in congeneric shrubs than congeneric lianas. The level of AMF colonization was also positively correlated with traits indicative of rapid plant growth and nutrient uptake. The concordance of a resource-acquisitive strategy with higher AMF colonization suggests that symbioses with AMF may be part of the strategy by which invasive woody plants of eastern North America are able to maintain fast growth rates and outcompete their native counterparts.

Early Maize (Zea mays) in the North American Central Plains: The Microbotanical Evidence

Artifacts, including ceramics, ground stone, and soil samples, as well as dental calculus, recovered from sites in the eastern North American central Plains were submitted to multiple laboratories for analysis of microbotanical remains. Direct accelerator mass spectrometer (AMS) dates of 361–197 cal BC provide evidence for the earliest use of maize (Zea maysssp.mays) in this region. Squash (Cucurbitasp.), wild rice (cf.Zizaniaspp.), and palm (Arecaceae sp.) microremains were also found. This research adds to the growing evidence of the importance of microbotanical analysis in documenting plant use and in the identification of early maize. The combined data on early maize from the eastern Plains adds to our understanding of the timing and dispersal of this crop out of the American Southwest. Alternative explanations for the adoption and early use of maize by eastern central Plains communities include its value as a secondary resource, as an addition to an existing farming strategy, or as a component of Middle Woodland rituals.

Revisiting the comparative phylogeography of unglaciated eastern North America: 15 years of patterns and progress.

In a landmark comparative phylogeographic study, “Comparative phylogeography of unglaciated eastern North America,” Soltis et al. (Molecular Ecology, 2006, 15, 4261) identified geographic discontinuities in genetic variation shared across taxa occupying unglaciated eastern North America and proposed several common biogeographical discontinuities related to past climate fluctuations and geographic barriers. Since 2006, researchers have published many phylogeographical studies and achieved many advances in genotyping and analytical techniques; however, it is unknown how this work has changed our understanding of the factors shaping the phylogeography of eastern North American taxa. We analyzed 184 phylogeographical studies of eastern North American taxa published between 2007 and 2019 to evaluate: (1) the taxonomic focus of studies and whether a previously detected taxonomic bias towards studies focused on vertebrates has changed over time, (2) the extent to which studies have adopted genotyping technologies that improve the resolution of genetic groups (i.e., NGS DNA sequencing) and analytical approaches that facilitate hypothesis‐testing (i.e., divergence time estimation and niche modeling), and (3) whether new studies support the hypothesized biogeographic discontinuities proposed by Soltis et al. (Molecular Ecology, 2006, 15, 4261) or instead support new, previously undetected discontinuities. We observed little change in taxonomic focus over time, with studies still biased toward vertebrates. Although many technological and analytical advances became available during the period, uptake was slow and they were employed in only a small proportion of studies. We found variable support for previously identified discontinuities and identified one new recurrent discontinuity. However, the limited resolution and taxonomic breadth of many studies hindered our ability to clarify the most important climatological or geographical factors affecting taxa in the region. Broadening the taxonomic focus to include more non‐vertebrate taxa, employing technologies that improve genetic resolution, and using analytical approaches that improve hypothesis testing are necessary to strengthen our inference of the forces shaping the phylogeography of eastern North America.

Project ButterBike, or Migrating with Monarchs

Dykman, Sara. 2021. Bicycling with Butterflies: My 10,201-Mile Journey Following the Monarch Migration. Timber Press, Portland, Oregon, USA. The Eastern North American monarch migration, spanning multiple countries and thousands of miles, has long fascinated ecologists, evolutionary biologists, and people of all backgrounds and ages alike. In Bicycling with Butterflies: My 10,201-mile Journey Following the Monarch Migration, Sara Dykman chronicles her expedition across Mexico, the United States, and Canada, cycling along monarch migration routes for nine months. Dykman is a gifted science communicator; she expertly walks readers through phenomena ranging from monarch physiology to coevolution to metapopulation dynamics, using language that is accessible to the general public but still informative to scientists. In this way, it is reminiscent of texts like Anurag Agrawal’s Monarchs and Milkweed (2017) and Sharman Apt Russell’s An Obsession with Butterflies (2004), but it stands out in that each phenomenon is vividly illustrated with Dykman’s personal anecdotes against the backdrop of her epic trip. The book is also an encyclopedia of the people who work with and advocate for monarch butterflies. Dykman details her interactions with guides to the sanctuaries in Mexico, Monarch Watch conservation specialists, “monarch celebrities,” and scientists alike, embodying them with glimpses into their conservation-focused backyards and homes that serve as waypoints throughout her journey. The practical details of her trip are also interesting. The themes of living on the road and cobbling together equipment may seem familiar to field biologists, and the logistics of undertaking such a long bicycle tour alone are fascinating. It is also where a missed opportunity for photographs stands out; as she describes biking along the Mississippi River, the Trans-Canada Highway, and the many other locales, some pictures would have been helpful, especially alongside her vivid descriptions of the ecological and cultural communities associated with each place. The map at the beginning of the book anchors each point of her route to the timing of each chapter effectively, but detailed pictures embedded in the chapters would have added extra clarity. Dykman’s perspective is an interesting one, as a person so captivated by monarch butterflies that she was motivated to bike the entirety of their migration route. In every chapter, her concern for the monarchs and wildlife in general is palpable as she stops to talk to passers-by about the environmental crisis and teach them when best to mow lawns to avoid killing insects, or to pick butterflies and turtles off the road. The gravity with which Dykman approaches these sections can seem a little heavy-handed in the bleakness of her outlook; although she is clearly earnest in trying to communicate the urgency of the situation to her readers, I imagine that most of her audience will already share her sentiments. In places, she also personifies the monarchs, which sometimes seems out of place besides the factually oriented sections on biology. In general, Bicycling with Butterflies is a worthwhile read, with pertinent pieces of information for everyone including cyclists, travelers, and people interested in ecology or the natural world. It serves both as an intriguing ecologist’s travel journal and as a thoughtfully presented compendium of monarch-related information.

Parasite dynamics in North American monarchs predicted by host density and seasonal migratory culling.

Insect-pathogen dynamics can show seasonal and inter-annual variations that covary with fluctuations in insect abundance and climate. Long-term analyses are especially needed to track parasite dynamics in migratory insects, in part because their vast habitat ranges and high mobility might dampen local effects of density and climate on infection prevalence. Monarch butterflies Danaus plexippus are commonly infected with the protozoan Ophryocystis elektroscirrha (OE). Because this parasite lowers monarch survival and flight performance, and because migratory monarchs have experienced declines in recent decades, it is important to understand the patterns and drivers of infection. Here we compiled data on OE infection spanning 50years, from wild monarchs sampled in the United States, Canada and Mexico during summer breeding, fall migrating and overwintering periods. We examined eastern versus western North American monarchs separately, to ask how abundance estimates, resource availability, climate and breeding season length impact infection trends. We further assessed the intensity of migratory culling, which occurs when infected individuals are removed from the population during migration. Average infection prevalence was four times higher in western compared to eastern subpopulations. In eastern North America, the proportion of infected monarchs increased threefold since the mid-2000s. In the western region, the proportion of infected monarchs declined sharply from 2000 to 2015, and increased thereafter. For both eastern and western subpopulations, years with greater summer adult abundance predicted greater infection prevalence, indicating that transmission increases with host breeding density. Environmental variables (temperature and NDVI) were not associated with changes in the proportion of infected adults. We found evidence for migratory culling of infected butterflies, based on declines in parasitism during fall migration. We estimated that tens of millions fewer monarchs reach overwintering sites in Mexico as a result of OE, highlighting the need to consider the parasite as a potential threat to the monarch population. Increases in infection among eastern North American monarchs post-2002 suggest that changes to the host's ecology or environment have intensified parasite transmission. Further work is needed to examine the degree to which human practices, such as mass caterpillar rearing and the widespread planting of exotic milkweed, have contributed to this trend.

The development of the eastern Orpheus rift basin, offshore eastern Canada: A case study of the interplay between rift-related faulting and salt deposition and flow

The salt-rich Orpheus rift basin, part of the eastern North American (ENAM) rift system, formed during the Late Triassic to Early Jurassic prior to opening of the Atlantic Ocean. Using a dense grid of 2D seismic-reflection lines, data from nearby wells, and information from adjacent ENAM rift basins, we have established a tectonostratigraphic framework, identified key structural elements, and reconstructed the deformation history for the eastern part of the basin. Our work shows that a series of E-striking, S-dipping faults with normal separation bound the basin on the north. Deformation within the basin is complex with forced folds above deep-seated intrabasin faults, detachment folds, detached thrust faults, and salt diapirs. The synrift evaporite sequence consists of an older massive salt unit that underlies a younger unit with two distinct interfingering facies. Facies A, consisting of salt and interbedded sedimentary rocks (likely shales), developed near the border-fault system and its relay ramps. Facies B, consisting of massive salt with few interbedded sedimentary rocks, developed toward the basin center. The youngest synrift unit accumulated exclusively within minibasins near the northern border-fault system. Based on location, this youngest synrift unit likely consists of coarse-grained and poorly sorted alluvial-fan or talus-slope deposits shed from the footwall. All synrift units are intruded by igneous sheets likely associated with the Central Atlantic Magmatic Province and, thus, are mostly Late Triassic in age (or possibly older). The border-fault system profoundly affected deposition within the eastern Orpheus rift basin by providing pathways for clastic sediment input into the salt-rich basin. These depositional patterns subsequently influenced deformation associated with lateral salt flow during minibasin formation. In regions with interbedded salt, detachment folds and thrust faults developed, whereas salt walls and stocks developed in regions with more massive salt.

Systematic revision of the Roseinae clade of Russula, with a focus on eastern North American taxa

ABSTRACT The Roseinae clade is a lineage of the genus Russula primarily composed of species of Russula subsect. Roseinae. Species in this morphologically distinct clade possess a white to pale cream spore print, mild taste, positive reaction to sulfovanillin, and primordial hyphae with acid-resistant crystals in the pileipellis. Here, we present a morphological and phylogenetic assessment that distinguishes seven eastern North American species of the core Roseinae lineage and a new subsection, Russula subsection Albidinae, to accommodate members of the Albida clade. We assign the previously described species R. peckii, R. rubellipes, and R. pseudopeckii to three species-level clades, and three other species, R. cardinalis, R. cordata, and R. rheubarbarina, are described as new. Comparative morphological analyses reveal differences in the conformation of terminal elements in the pileipellis, spore size, hymenial cystidia contents, and pigmentation on the stipe surface as key features to recognize species in the group. Based on the analysis of publicly available data, we recognize a potential total of nine temperate North American species within R. subsect. Roseinae, in addition to four from Central America, two from Europe, and 14 from Asia.

Stand and site characteristics affect the probability of stump sprouting in some eastern North American hardwoods

Stump sprouting is a widespread phenomenon in North American hardwood tree species following logging or severe crown damage from natural disturbances such as fire, wind, or insect attack. However, other than the effects of species and tree size, factors that influence the probability of sprouting are not well understood. Data from harvested stands in Pennsylvania and Connecticut, USA, were used to evaluate the effects of several variables on stump sprouting frequencies measured within the first year after cutting for several oak and other hardwood species. After adjusting for species and diameter of the “parent” tree (ortet), clearcut harvests were found to result in a higher frequency of sprouted stumps than shelterwood harvests or crop tree releases. In addition, the probability of sprouting was higher for trees in the Ridge and Valley province of Pennsylvania vs. the Appalachian Plateaus, and in general it was higher on dry vs. moist sites. After accounting for all measured variables, there remained statistically significant stand-to-stand differences in sprouting frequency that arose from unknown causes. Results should temper expectations of stump sprout contributions to regeneration stocking that are based on simple models derived from a small number of stands or a limited geographic area. On the stand-level basis at which most managers work, the actual contribution of sprouts to future stand development may vary widely from modeled expectations.