It is widely thought that many apomictic angiosperms exhibit variation in sexual versus apomictic seed production, yet there has been little investigation of the extent to which apomixis varies among or within natural populations. In dioecious Antennaria parlinii, previous...
We examined whether experimental parasitism by a mite Limnochares americana (Lundblad) affected survivorship and maturation of adult damselflies Enallagma ebrium (Hagen). We then tested whether differences in grooming activity between control and exposed individuals (within different age or sex categories...
In self-compatible plants, small populations may experience reduced outcrossing owing to decreased pollinator visitation and mate availability. We examined the relation between outcrossing and population size in eastern Ontario populations of Aquilegiacanadensis. Experimental pollinations showed that the...
Tree swallows (Tachycineta bicolor) show one of the highest levels of extrapair paternity in birds, and there is evidence that females have control over who fathers their offspring. However, it is unclear which benefits female tree swallows obtain...
The proportion of extrapair paternity is known to vary greatly among species, but differences between populations of the same species have rarely been considered. We used microsatellite DNA markers to assess parentage of offspring in a subarctic population of the...
The theoretical construct of an optimal offspring size remains widely cited in life history literature, despite the regular failure of the central prediction of that theory, that offspring size should not vary within populations. Here we used data from 77...
Mating systems and sexual selection are assumed to be affected by the distribution of critical resources. We use observations of 312 mating aggregations to compare mate-searching success of male northern water snakes (Nerodia sipedon) in two marshes in...
Floaters are sexually mature yet nonbreeding, nonterritorial individuals (Smith 1978). They are common in many passerine species and avian social systems (see Zack and Stutchbury 1992) but relatively little is known about them. Floating behavior ultimately arises through an excess...
We used data from a nine-year study to assess how these factors contribute to female-biased sexual size dimorphism in males, although both sexes approached their asymptotic size at the same rate.
We investigated the distribution of variation at six microsatellite loci in the black rat snake (Elaphe obsoleta obsoleta). Sampling occurred at three hierarchical scales ranging from communal hibernacula to regional populations, with most locales situated within the Frontenac...
The loss of traits that no longer increase fitness is a pervasive feature of evolution, although detailed studies of the genetic, developmental, and evolutionary factors involved are few. Most perennial plants practice both sexual and clonal reproduction, and it has...
We describe the isolation and genetic characterization of eight microsatellite DNA loci from the northern water snake, Nerodia sipedon sipedon and use these loci to analyse levels of genetic differentiation between local (<2km apart) populations of these snakes in Ontario...
We describe 10 microsatellite loci from bluegill (Lepomis macrochirus) and discuss their evolution within the Centrarchidae. All of the loci exhibit Mendelian inheritance and are unlinked. While six loci are conserved within the Centrarchidae (found also in pumpkinseed...
Female Black-capped Chickadees (Poecile atricapillus) solicit extrapair copulations (EPCs) from neighboring high-ranked males, and these EPCs result in extrapair young. Females might choose to locate their nests near the territory boundaries of attractive males to facilitate access to...
Using field surveys and histological methods, we show that a dragonfly species (Sympetrum internum) has an effective resistance, not seen previously in other odonates, to a mite parasite (Arrenurus planus). This mite is a generalist parasite...
The size and shape of the black bib in Black-capped Chickadees varies among individuals and may signal information about age and sex, as found in other species with similar plumage badges. By photographing and measuring bibs of wintering adults in...
Studies aimed at determining why female birds often produce offspring sired by males other than their social mates generally compare traits of social and genetic mates. Here I examine paternity patterns in nests of the same female red–winged blackbirds (...
Data from five pumpkinseed sunfish (Lepomis gibbosus) populations were used to generate age‐specific survival rates and to test the prediction of life history theory that early maturity and high annual reproductive effort are favored by low adult survival...
In this study, we examined the constraints of nestbox size on nestling growth and survival while controlling for variation in clutch size and parental quality.
Ears exist in moths primarily for the purpose of detecting hunting bats at night to avoid predation. The ears of four species of day-flying Nearctic moths are as sensitive as those of a common, night-flying genus to the frequencies emitted...
here has been much recent interest in subtle departures from perfect symmetry in bilaterally paired morphological characters, and the extent to which such departures reflect aspects of individual quality. We used data from aviary contests involving pairs of wild-caught male...
Recent evidence suggests that in many animal taxa, males characterized by low levels of bilateral asymmetry realize a mating advantage. The mechanisms responsible are poorly understood, but there is much interest in the possibility that symmetry reflect, aspects of underlying...
Extra-pair paternity is common in many socially monogamous passerine birds with biparental care. Thus, males often invest in offspring to which they are not related. Models of optimal parental investment predict that, under certain assumptions, males should lower their investment...
Male birds are often faced with low confidence of paternity in their mates' offspring, raising the question of how paternal care covaries with confidence of paternity. We tested the hypothesis that male eastern bluebirds (Sialia sialis) reduce care...
Previous studies have shown that some female black-capped chickadees (Poecile atricapillus) solicit copulations from males that rank higher in winter flocks than their social mates, and extra-pair paternity in nests occurs commonly enough to be considered a potential...
The ability to produce seeds when pollinators or potential mates are scarce is thought to be one of the main advantages of self-fertilization in flowering plants. However, whether autonomous selfing increases seed set in natural populations has seldom been tested...
The effects of shoot apex removal may be used to evaluate the cost of apical dominance and the cost of reproduction in plants. Plants that have shoot apices removed may have lateral meristems released from apical dominance and thus, may...
Before the onset of female fertility, we removed 12 early–settling male tree swallows (Tachycineta bicolor) from their nest–boxes and mates, and allowed replacement males which had been floaters to settle with the original female residents. We predicted that...
Our aim was to determine the rate of extrapair paternity in Eastern Phoebes using DNA fingerprinting. We also wanted to see if the frequency of EPY changed between the first and second broods of the season.
We inadvertently examined homing ability in Tree Swallows when we removed twelve males from their nestboxes in 1993 as part of another study. These males were removed just prior to their mate's fertile period and released either 125 or 250...
It has been proposed that the most sensitive auditory receptor cell (A1) in the two-celled ears of certain noctuoid moths is inhibited by its partner, the A2 cell, at high stimulus intensities. We used the single-celled ears of notodontid moths...
We used morphological and breeding data from a 2-year field study of red-winged blackbirds (Agelaius phoeniceus) to test the hypothesis that males characterized by low levels of bilateral asymmetry (i.e., high developmental competence) realize a reproductive advantage. Specifically...
We used data from 88 litters of northern water snakes (Nerodia sipedon) to test predictions about how mothers would adaptively vary the sex ratios of their offspring. Larger mothers produced significantly more daughters (r2 = 0.04, P = 0.05), and...
In an experimental study in Denmark, it was previously found that male barn swallows (Hirundo rustica) with elongated tail streamers obtained an apparent fitness advantage through earlier pairing, an increased frequency of second clutches, and higher total reproductive...
Using data from a 6-year paternity study of red-winged blackbirds, I tested the hypotheses that increased nesting synchrony should either promote extra-pair mating by increasing the advantage of extra-pair mating to females, or decrease extra-pair mating by constraining males from...
The influence of frequent water-column mixing on phytoplankton succession and species composition was studied by comparing plankton dynamics in two lakes (Lake Opinicon and Upper Rock Lake) which have similar water chemistry, but differ widely in their basin morphometries: Opinicon...
Larval damselflies resist infestation by parasitic larval mites by exhibiting behaviours such as grooming, crawling, swimming, and striking at host-seeking mites. Larval damselflies are known to increase time spent in these behaviours in the presence of mites but reduce time...
There is growing evidence that many self‐compatible plants control the level of self‐fertilization with postpollination processes that give a siring advantage to cross pollen over self pollen through “cryptic self‐incompatibility” (CSI). Previous marker‐gene experiments with self‐compatible, tristylous Decodon verticillatus (Lythraceae)...
Although a goal of fisheries management is to understand factors affecting the growth rate and size structure of exploited populations, the relation between growth rates and variation in reproductive behaviors in Lepomis species has received little attention. Allocation of energy...
The cornerstone of life-history theory is the expectation that current reproduction will have a detrimental effect on survival and (or) future reproduction. When fecundity increases with body size, the cost to future reproduction arises through decreased growth of reproductive individuals...
Hypotheses about the role of selection on body-shape evolution assume a heritable component to this phenotypic character. To examine the influence of environmental induction on body shape, offspring form two morphologically differentiated populations of northern redbelly dace (Phoxinus eos...
Extra–pair mating has been proposed as a source of sexual selection responsible for secondary sexual traits that are common among socially monogamous birds, although supporting evidence is scant. In the socially monogamous yellow warbler, males are larger than females, and...
Fluctuating asymmetry (FA) refers to random deviations from symmetry of otherwise bilaterally symmetric traits. Researchers have hypothesized that FA should be inversely related to individual quality or fitness. In this study, we tested for FA-quality and FA-fitness relations in the...
DNA‐based methods of determining parentage in birds have revealed that apparent reproductive success can be very different from true reproductive success. Our main goal in this study was to provide estimates of true annual and lifetime reproductive success of male...
We examined the geographic distribution of biochemical genetic and life history characteristics of 16 populations of pumpkinseed Lepomis gibbosus within four east-central Ontario watersheds to determine (1) if populations within watersheds were more alike for either of these traits than...
Costly signals can evolve under sexual selection, as only those signals that are difficult to produce and reflect the relative quality of individuals should be important in mate choice. One such signal may be dawn singing behavior in birds. We...
An understanding of diet selection in animals requires knowledge of not only what animals eat in relation to what is available, but also how they perceive the foods available to them. Birds use auditory, visual, olfactory and possibly vibrotactile cues...
We characterized the morphology of mature cuckolder and mature parental male bluegills Lepomis macrochirus from Lake Opinicon, Ontario. By rearing bluegill larvae to maturity in experimental ponds in Illinois we also examined whether morphological differences between males of the two...
We tested the hypothesis that larger individuals in a temperate fish population emerge from winter in better energetic condition than do smaller individuals. We sampled adult male bluegills Lepomis macrochirus in Lake Opinicon, Ontario, after spring ice break and just...
Assessments of population genetic structure and diversity can be of value in formulating management plans for threatened species. Using randomly amplified polymorphic DNA markers, we found evidence of significant genetic structure among black rat snakes ( Elaphe obsoleta) sampled at three...
We found high population densities of Hydra canadensis (up to 30,000 m ‘) on macrophytes in Lake Opinicon (Ontario, Canada) and tested whether they influenced the survival of larval bluegill, Lepomis macrochirus. Hydra were observed to capture and ingest bluegill...
We investigated the relative effects of low pH and high iron on a water mite, Arrenurus manubriator and an aquatic insect, Chironomus riparius. Eggs and active stages were exposed in static renewal toxicity tests to pH 6, 5, 4...
Depending on the circumstances under which extra-pair mating occurs, theory makes opposing predictions about how reproductive synchrony should influence extra-pair paternity. This study investigated which sex initiated extra-pair mating in the yellow warbler, whether extra-pair behaviour and extra-pair paternity were...
Current management strategies for black bass Micropterus spp.—specifically, largemouth bass M. salmoidesand smallmouth bass M. dolomieu—sometimes incorporate regulations with closed fishing seasons during reproductive activities. Our field study investigated how well anglers were complying with Ontario's closed black...
Current management strategies for black bass Micropterus spp.—specifically, largemouth bass M. salmoides and smallmouth bass M. dolomieu—sometimes incorporate regulations with closed fishing seasons during reproductive activities. Our field study investigated how well anglers were complying with Ontario's closed black...
