Mean daily mobility estimates for smallmouth bass Micropterus dolomieu from mark‐recapture (47·5±12·5 m) were less than from conventional telemetry (77·1±10·6 m). The relationship developed in a respirometer between the activity transmitter and swimming speed (r2=0·99, P < 0·001, ...
Lake eutrophication is a problem in many areas of Ontario, although the history of nutrient enrichment is poorly documented. The aim of this study was to construct a diatom-based transfer function to infer past phosphorus levels in Ontario lakes using...
We measured the 24-h flight activity patterns of 84 species of Nearctic Lepidoptera representing 12 ultrasound-earless and seven ultrasound-eared families to examine the evolution of the diel flight periodicities (DFPs) and auditory defences of these insects. Most species tested showed...
Theories of parental care evolution predict that genetic relatedness will be an important variable in the amount of care a parent provides. However, current inferences of relatedness–based parental investment from studies in humans and birds remain challenged. No study has...
It is generally expected that small, isolated populations will suffer reduced fitness due to inbreeding, yet few studies have investigated the relation between population characteristics, inbreeding and fitness. Among Ontario populations of the short‐lived, perennial plant Aquilegia canadensis, large...
Gender in flowering plants is governed by a complex interplay of genetic and environmental factors. The perennial aquatic herb Sagittaria latifolia displays remarkable variation within and among populations in gender expression, from monoecious populations composed of plants with differing numbers...
Fish have some of the most complex mating systems known in the animal kingdom. With the advent of powerful genetic markers and an emerging mathematical framework to calculate parentage, it is now possible to analyze genetic relatedness and gene flow...
Declining nest success of forest birds in fragmented habitat has been attributed to increased nest predation. Better understanding of this problem and potential solutions to it require information on why nest predators are attracted to habitat edges. Toward this end...
Molecular genetic studies have suggested that apparently nonbreeding males (‘floaters’) may account for a significant proportion of extra‐pair paternity (EPP) in avian populations. Attempts to determine the influence of breeding density on EPP are therefore confounded by the presence of...
Sociality is associated with increased risks of parasitism, predation, and social competition, which may interact because social stress can reduce immunity, and parasitized individuals are more likely to fall prey to a predator. A mechanism allowing evolution of sociality in...
Life history theory predicts that ectotherms living in warm thermal environments should mature early because of fast juvenile growth, but it is unclear whether such early maturity will occur in the absence of conditions that promote fast juvenile growth. To...
In January 1998, the worst ice storm of the last century hit regions of southeastern Ontario, Quebec, New Brunswick, and the northeastern United States. Using multiple standard regression and classification trees, we examined the ice damage in a mature, deciduous forest...
Long-term data collected from an old-field community suggest that physical and environmental patterns alone may be insufficient to account for different patterns of succession. Using a simple Lotka–Volterra model to represent competition between early and late succession guilds, we add...
Increased mortality in the presence of stress may result from stress-reduced availability of energy for immune function, coupled with the presence of pathogens or parasites. We tested the hypothesis that stress reduces antiparasite responses of damselflies Ischnuraverticalis (Hagen) to...
Immune ability and immune expression have been viewed as life-history traits that are influenced by such factors as the likelihood of being parasitized, intensity and costs of parasitism, and trade-offs associated with immune expression. In this paper we show that...
The spawning behavior of male and female largemouth bass Micropterus salmoides (Lacépède) was studied in central Illinois during the spring of 1998 to examine patterns of muscular activity associated with different spawning related behaviors and to evaluate whether electromyogram (EMG...
Least flycatchers (Empidonax minimus) are socially monogamous birds that form tight territorial aggregations on the breeding grounds. We designed five polymorphic microsatellite loci for assigning parentage to offspring within least flycatcher clusters. The number of alleles per locus...
Population ecology requires reliable population samples. We assessed sampling reliability for black rat snakes (Elaphe obsoleta) using 1724 captures obtained by two different methods: trapping at communal hibernacula and opportunistic capture of snakes at large. Recapture intervals indicated that opportunistic...
Milkweed leaf beetles (MLBs; Labidomera clivicollis Chrysomelidae) are parasitized by a subelytral mite, Chrysomelobia labidomerae (Tarsonemina: Podapolipidae). We show that C. labidomerae is transmitted between MLBs when they copulate, and can reduce the survival of nutritionally stressed beetles. We investigated...
Sperm competition is a major force in sexual selection, but its implications for mating–system and life–history evolution are only beginning to be understood. The well–known sneak–guard model predicts that sneaks will win in sperm competition. We now provide empirical confirmation...
We examined habitat selection by breeding Cerulean Warblers (Dendroica cerulea) at three spatial scales in eastern Ontario over three years (1997–1999). Territories were characterized by well-spaced large trees, with high canopies and dense foliage cover at heights between...
We studied the effects of catch‐and‐release angling on rock bass Ambloplites rupestris a small but common centrarchid species in North America. A field study of hooking injury and mortality was conducted in Lake Erie at a water temperature of 16°C...
A general model in thermal ecology predicts that ectotherms should stop thermoregulating when the costs outweigh the benefits. Support for this model comes from studies of warm‐temperate species, but the extent to which the model can be extrapolated to species...
Mites belonging to several unrelated groups are commonly found in freshwater habitats. The true water mites comprise a taxon of actinedid acariform mites, which is referred to as Hydrachnidiae. Hydrachnidiae have flourished to become by far the most numerous...
Syrinx is a newly developed PC-based software package designed for interactive playback of animal vocalizations and for digital sound recording and analysis in the lab or in the field. Syrinx permits flexible modeling of complex vocal interactions in an interactive...
While studying the nesting ecology of black rat snakes (Elaphe obsoleta [Say]; Serpentes: Colubridae) in eastern Ontario, we discovered that their eggs regularly contained larvae of the burying beetle Nicrophorus pustulatus (Herschel) (Coleoptera: Silphidae). The beetle appears to be...
If the primary function of ultrasound-sensitive ears in Lepidoptera is to detect the echolocation calls of insectivorous bats, diurnal species should exhibit signs of ultrasonic deafness. To test this hypothesis we recorded the 24-h (diel) flight activity of a sample...
Chironomid (Diptera: Chironomidae) head capsules were studied from a core of recent sediments from shallow, macrophyte-dominated Lake Opinicon, Ontario, Canada, to determine if assemblages have changed in response to lake-level changes and other watershed disturbances, including deforestation and agriculture. Our...
The fitness consequences of self‐fertilization are largely determined by how self‐pollination occurs. Within‐flower self‐pollination (autogamy) may be advantageous, since it can provide reproductive assurance without much seed or pollen discounting. In contrast, between‐flower self‐pollination (geitonogamy) provides no reproductive assurance and...
While studying the nesting ecology of black snake rats ( Elaphe obsoleta [Say]; snakes : Colubridae) in eastern Ontario, we discovered that their eggs were very well protected by the Nicrophorus pustulatus (Herschel) (Coleoptera: Silphidae). The beetle appears to be parasitoid of the...
This study investigated the accuracy of 50-m fixed-radius, 100-m fixed-radius, and variable circular-plot point counts to estimate the actual density of breeding Cerulean Warblers (Dendroica cerulea) during the 1997 and 1998 breeding seasons, in Ontario, Canada. Density estimates were compared...
We stored blood samples of Eastern Phoebes (Sayornis phoebe) in a lysis buffer (“QLB”) that has been used successfully to preserve blood samples of many other species. We found that although samples from adults were not affected greatly...
Directional asymmetry (DA) has received considerably less attention than fluctuating asymmetry (FA) in the literature. Evidence for DA, however, is building among insect taxa. We examined asymmetries in two wing traits within both sexes of the damselfly Calopteryx maculata (Beauvois)...
Patterns of divorce and extrapair mating can provide insights into the targets of female choice in free-living birds. In resident, site-faithful species with continuous partnerships, the better options and the incompatibility hypotheses provide the most likely explanations for divorce. Extrapair...
Dichogamy is very common in flowering plants and is widely thought to reduce pollen‐pistil interference, especially self‐pollination. Yet, the functional significance of dichogamy has rarely been studied. We investigated the nature and functioning of dichogamy in eastern Ontario populations of ...
In many avian species, a part of the population is present at the breeding grounds but does not breed. Current theories generally assume that floaters are younger or lower-quality individuals, and empirical data confirm this. However, floating could also arise...
T.--We used data from an 11-year study of Red-winged Blackbirds (Agelaius phoeniceus) totest the hypothesis that fledging success is a reliable index of recruitment at the population and the individual level. Natal philopatry was only 2.37% overall (3.51% for males...
It has been suggested that fluctuating asymmetry (FA) is an indicator of perturbed development. Our study tests the validity of a fundamental assumption of asymmetry theory: that environmental stress imposed during development increases FA. We deprived tree swallow (Tachycineta...
Traditional population genetics theory assumed that at some level in the hierarchy of genetic diversity there existed 'demes' in which males and females mate at random. Polygynous mating systems or individual variance in reproductive success were considered complications which altered...
Catch‐and‐release angling of black bass Micropterus spp. during the parental care period may lead to brood predation and premature nest abandonment. Furthermore, physiological disturbance incurred while landing angled males may impair their ability to provide parental care long after release...
Least Flycatcher Empidonax minimus pairs form dense clusters of territories on the breeding grounds. We describe pair formation and copulation behavior (both within- and extra-pair) in Least Flycatcher clusters. Pair formation involved a complex behavioral sequence of trill vocalizations and...
Paleolimnological techniques were used to infer long-term changes in trophic status of Lake Opinicon (Ontario), a mesotrophic, shallow, macrophyte-dominated lake, and to assess whether these patterns support the hypothesis of 'alternative equilibria' proposed for shallow lake systems. Analysis of the...
Many breeding systems include ‘multiple mating’ in which males or females mate with multiple partners. We identify two forms of multiple mating: ‘single‐sex’, where the next‐generation individuals (NGIs) are the product of multiple mating by one sex; and ‘two‐sex’, where...
Substantial individual variation in timing of emergence from hibernation has been reported among reptiles. Here we report patterns of spring emergence by black snake rat (Elaphe obsoleta obsoleta) observed at 13 communal hibernacula in eastern Ontario from 1992-1997. Because our study is...
We investigated whether the thermal history of Black Rat Snakes (Elaphe obsoleta) and Northern Water Snakes (Nerodia sipedon) during development affected their preferred body temperatures (PBT) after hatching or birth. Eggs of black rat snakes were...
Interspecific comparisons suggest that a trade-off exists between development and somatic growth rate. We provide evidence for a trade-off between cranial ossification and growth rate within a single species, the pumpkinseed sunfish (Lepomis gibbosus). We compare fish derived...
Avian populations often consist of breeding residents and nonbreeding floaters. It is usually assumed that floaters are lower-quality individuals that do not reproduce, but floater tactics and potential reproductive success have rarely been examined carefully. To assess the potential reproductive...
We tested the responses of two bird species which nest on unmovable substrates (e.g., cavities and walls) to simulated and actual egg damage in their nest. Tree Swallows (Tachycineta bicolor) and Barn Swallows (Hirundo rustica) removed...
Sexual dimorphism is a widespread phenomenon among animals (Darwin, 1871; Andersson, 1994). Differences between the sexes come in many forms, in- cluding both morphology (e.g., size, shape, coloration) and behavior (e.g., risk-taking or defensive behavior). Sexual differences in physiology also...
Genomic introgression among divergent taxa following human-mediated secondary contact is a growing concern for the management and conservation of aquatic biodiversity. We simulated the composition of taxa following admixture and hybridization by independently altering three variables: (1) initial proportion of...
We examined the availability and motility of sperm from parental and sneaker male bluegills (Lepomis macrochirus), a colonially nesting sunfish (Family Centrarchidae) with male parental care and a high incidence of cuckoldry by both sneaker and satellite males...
We used more than 326 000 observations of temperature collected by radio telemetry from 38 individuals over three years to investigate thermoregulation and thermal relations of northern water snakes (Nerodia sipedon) near the northern limit of their distribution in...
Different snake species respond differently to various anesthetic agents. Hence, an anesthetic procedure developed for one species cannot necessarily be safely transferred to another species. The goal of this paper is to summarize our experience using inhalant anesthetics on three...
Butomus umbellatus L. is an invasive emergent aquatic plant that exhibits wide variation in seed production. Native European populations are fertile and diploid or sterile and triploid. However, adventive North American populations are widely reported to be sexually sterile. We...
Brown recently proposed that the “good genes” that females pursue when choosing mates may be individual heterozygosity because more heterozygous mates sire offspring with higher fitness. Further, because heterozygosity might enhance developmental stability, males with more heterozygosity are recognized by...
We used data from a 9-year mark–recapture study to determine whether demographic factors could explain female-biased sexual size dimorphism in northern water snakes (Nerodia sipedon). Most males reached sexual maturity at 3 years of age, while most females delayed maturity...
