John Acorn

John Acorn
University of Alberta | UAlberta · Department of Renewable Resources

About

99
Publications
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416
Citations
Citations since 2017
35 Research Items
359 Citations
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20172018201920202021202220230204060
20172018201920202021202220230204060

Publications

Publications (99)
Article
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Conservation biologists have long debated the value of subspecies, which are morphologically and geographically identifiable but not necessarily evolutionarily distinctive. One example of a controversial subspecies is Cicindela formosa gibsoni, a tiger beetle that is nationally listed as threatened in Canada and whose taxonomic status is based prim...
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The island species area relationship (ISAR) is an important tool for measuring variation in species diversity in variety of insular systems, from true‐island archipelagoes to fragmented terrestrial landscapes. However, it suffers from several limitations. For example, due to the sample‐area effect, positive relationships between species and area ca...
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In winter, Gyrfalcon (Falco rusticolus) and Prairie Falcon (Falco mexicanus) frequent a 96-year-old grain terminal, in Edmonton, Alberta, hunting Rock Pigeon (Columba livia). This phenomenon was reviewed shortly after it was first noticed by others in 1998 and, since then, we have observed hunting success and methods of Gyrfalcons and Prairie Falco...
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Histerid beetle (Histeridae) phenology and habitat associations were inferred from specimens collected in pitfall traps on a grassland dune field near Empress, Alberta, Canada, during 3 May to 27 August 1984. Four vegetation associations were identified by cluster analysis (Scurf Pea, Open Sand, Stabilized Dune, and Sand Flat) and 516 histerid beet...
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Previous work in landscape genetics suggests that geographic isolation is of greater importance to genetic divergence than variation in environmental conditions. This is intuitive when configurations of suitable habitat are the dominant factor limiting dispersal and gene flow, but has not been thoroughly examined for habitat specialists with strong...
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The Cretaceous birds of Alberta are poorly known, as skeletal elements are rare and typically consist of fragmentary postcranial remains. A partial avian coracoid from the upper Campanian Dinosaur Park Formation of Alberta, Canada can be referred to the Ornithurae, and is referred to here as Ornithurine G (cf. Cimolopteryx). Its structure is simila...
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The challenge of understanding how composite disturbances affect ecosystems is a central theme of modern ecology. For instance, anthropogenic footprints and wildfire are increasing globally, but how they combine remains poorly understood. Here, we assessed how a disturbance legacy of about 10-m-wide cutlines, cleared for seismic assessments of foss...
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Estimating distribution and abundance of species depends on the probability at which individuals are detected. Butterflies are of conservation interest worldwide, but data collected with Pollard walks - the standard for national monitoring schemes - are often analyzed assuming that changes in detectability are negligible within recommended sampling...
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The pronounced morphological variability exhibited by Speyeria butterflies can hinder the identification of these taxa, and thus presents a challenge to their management and conservation. While several studies have documented declines in American populations of Speyeria due to habitat change, the response of Canadian populations of Speyeria to wide...
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Butterflies are widely invoked as model organisms in studies of metapopulation and dispersal processes. Integral to such investigations are understandings of perceptual range; the maximum distance at which organisms are able to detect patches of suitable habitat. To infer perceptual range, researchers have released butterflies at varying distances...
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Leaping somersaults and their associated behaviors are documented in four distantly related genera of tiger beetles and are therefore likely a primitive ability. When prodded or pinched on their abdomen, simulating the sting of a methochine thynnid wasp, larvae of the tiger beetles Omus dejeani Reiche, Tetracha carolina (Linnaeus), Cicindela duodec...
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The boreal forest in Canada comprises a wide variety of ecosystems, including stabilized (overgrown) sand dunes, often referred to as sand hills. Globally, sandy soils are known for supporting a high diversity of invertebrates, including ants, but little is known for boreal systems. We used pitfall trap sampling in sand hill, aspen parkland and pea...
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Aim Investigate relationships between fragmentation and species diversity in the context of the theory of island biogeography, sample‐area effect, and habitat diversity hypothesis. Location Lake of the Woods, Canada. Taxon Vascular plants Methods Vascular plant species diversity was inventoried on 30 islands, organized into two island sets. Each...
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Monarch butterflies ( Danaus plexippus (Linnaeus) (Lepidoptera: Nymphalidae)) in eastern North America migrate each year from overwintering areas in Mexico to cover a large breeding distribution across the United States of America and southern Canada. In 2012, monarch butterflies migrated well beyond their usual range, resulting in an extended bree...
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Cranberry blues (Agriades optilete) are butterflies of conservation interest worldwide. Less than 20 populations are known in Alberta, Canada, mostly inhabiting boreal forests that are increasingly fragmented by oil sands developments and subject to wildfires. We modeled the abundance of cranberry blues in the boreal forests of Alberta’s Wood Buffa...
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Partial retention harvest (PRH) has received attention as an alternative to clear-cutting, yet most studies of its effects on boreal songbirds have been conducted shortly after harvest. We assessed responses of songbird assemblages to PRH over a 15-year post-harvest period at the EMEND experiment in the mixedwood forest of Alberta, Canada. Four par...
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Species delimitation and identification are integral to virtually all biological disciplines, but are far from straightforward tasks. Taxonomy has recently focused on integrative approaches that consider multiple types of data to resolve species boundaries, yet methodologies to that end are still being developed. Here, we assess species limits in a...
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Ecological and anthropogenic corridors are becoming more common worldwide, but little is known about how corridor size (width) affects species' movements, and thus their effects. Here we investigated whether 4- and 8-m wide anthropogenic corridors (seismic lines) cleared for petroleum (oil sands) exploration in boreal forests in Alberta, Canada, ac...
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Since the publication of the theory of island biogeography, ecologists have postulated that fragmentation of continuous habitat presents a prominent threat to species diversity. However, negative fragmentation effects may be artifacts; the result of species diversity declining with habitat loss, and habitat loss correlating positively with degree o...
Article
Understanding species responses to changes in habitat is a primary focus of biodiversity conservation, especially when assessing widespread anthropogenic disturbance. Extraction of Alberta's subterranean oil sands by wells requires extensive networks of cleared linear disturbances (“in situ” extraction) that result in widespread, but localized incr...
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Citizen science involves voluntary participation in the scientific process, typically by gathering data in order to monitor some aspect of the natural world. Entomological citizen science, as an extension of traditional amateur entomology, is an active field in Canada, with online databases such as eButterfly and BugGuide attracting both contributo...
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Among the largest and most abundant aquatic predators during much of the early evolution of vertebrates, eurypterids have long been an iconic and intensely studied group of Paleozoic arthropods. We report a new specimen of the eurypterid Slimonia acuminata, which includes a fully articulated series of tail (postabdominal and telsonal) segments pres...
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Species richness and evenness, the two principle components of species diversity, are frequently used to describe variation in species assemblages in space and time. Compound indices, including variations of both the Shannon–Wiener index and Simpson’s index, are assumed to intelligibly integrate species richness and evenness into all-encompassing m...
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Based on field surveys, museum specimens, and published literature, we document 73 ant species in three subfamilies and 12 genera for the province of Saskatchewan, Canada. An additional 16 species are known from surrounding regions and are likely to occur in Saskatchewan.
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Over two summers following accidental May wildfires, total ant (Hymenoptera: Formicidae) forager catch and species richness did not change in jack pine woodlands on sand hills in central Alberta, Canada. However, one year after a fire, smaller ants, and those in smaller colonies, were more abundant in pitfall traps, based on analysis of response ra...
Chapter
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A list of 53 species of ants, all known from the grassland regions of Alberta and Saskatchewan, is presented, along with collecting localities and annotations regarding the biology of each species. As the fauna is not well-known, this list is considered preliminary. Résumé. Ce chapitre présente une liste de 54 espèces de fourmis décrites dans les r...
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Fossil mayfly larvae (cf. Heptageniidae) are reported for the first time in the Cretaceous of Canada. The new fossils come from the latest Campanian part of the Wapiti Formation, which crops out in west-central Alberta, near the British Columbia border. These sediments represent mixed lentic and lotic fluvial environments consistent with modern hep...
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Using for comparison with, and as outgroups for, supertribe Cicindelitae, we describe and illustrate the mandibles and labrum-epipharynx of the basal geadephagans Trachypachus gibbsii LeConte, 1861 (family Trachypachidae), and family Carabidae: Pelophila rudis (LeConte, 1863) (supertribe Nebriitae, tribe Pelophilini) and Ceroglossus chilensis (Esch...
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The structure of carabid and other adephagan mandibles can provide information about the mechanics of feeding in these beetles and about the major features of carabid and adephagan evolution. Homologies among mandibular features are proposed, based on a transformation series for adult mandibles from plesiotypic cupedid-like structure to derived con...
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Chapter
This chapter discusses various entomology-teaching resources. Those who teach about insects in the entomological sense, the best resources have always been a good entomological library, a selection of live insects in culture, a well-maintained collection of preserved specimens, and somewhere to take students to see live insects behaving in a natura...
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Alberta is well known for its fossil treasures, and author John Acorn is as keen on the long-dead creatures of Alberta as he is on the living. Here, John features 80 of the most noteworthy fossils, fossil locations, and fossil hunters from this most palaeontological of provinces. There's more to the story of "deep Alberta" than dinosaurs, but dinos...

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Project (1)
Archived project
In my Ph.D. thesis, I assessed anthropogenic changes related to the extraction of oil sands in boreal forests using butterflies as focal organisms.