8 results
Search Results
2. Quantifying partial migration with sex-ratio balancing
- Author
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Chris E. Jordan, David A. Lytle, Haley A. Ohms, and Alix I. Gitelman
- Subjects
0106 biological sciences ,010604 marine biology & hydrobiology ,Animal migration ,behavior and behavior mechanisms ,Zoology ,Animal Science and Zoology ,Biology ,010603 evolutionary biology ,01 natural sciences ,Ecology, Evolution, Behavior and Systematics ,Sex ratio - Abstract
Partial migration, the phenomenon in which animal populations are composed of both migratory and nonmigratory individuals, is widespread among migrating animals. The proportion of migrants in these populations has direct influences on population genetics and dynamics, ecosystem dynamics, mating systems, evolution, and responses to environmental change, yet there are very few studies that measure the proportion of migrants. This is because existing methods to estimate the proportion of migrants are time-consuming and expensive. In this paper, we demonstrate a new method for estimating the proportion of migrants in a population based on sex ratio measurements. Many partially migratory taxa exhibit sex-biased migration or residency, and in these cases, the sex ratios of migrants and nonmigrants are fundamentally related to the proportion of migrants in the population. We define this relationship quantitatively and show how it can be used to infer the proportion of migrants in a population through a process we term “sex-ratio balancing”. We obtain Bayesian estimates of proportion of migrants and quantify the uncertainty in these estimates with highest posterior density intervals. Lastly, we validate the sex-ratio balancing approach with a Chinook salmon (Oncorhynchus tshawytscha Walbaum in Artedi, 1792) data set. Sex-ratio balancing holds promise as a tool for quantifying partial migration and filling a key data gap about partially migratory taxa.
- Published
- 2019
3. Richness and zoogeography of ascidians (Tunicata: Ascidiacea) in eastern Canada
- Author
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Kevin C. K. Ma, Maria Lourdes D. Palomares, Don Deibel, Cynthia H. McKenzie, Mai Aoki, and Kenneth K. M. Law
- Subjects
0106 biological sciences ,Ecology ,010604 marine biology & hydrobiology ,Zoology ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Indigenous ,Zoogeography ,Animal Science and Zoology ,Species richness ,Ecology, Evolution, Behavior and Systematics ,Ascidiacea - Abstract
Managers and policymakers in eastern Canada embrace science-based management of nonindigenous species and may benefit from having comprehensive regional species checklists at subnational jurisdictional levels. In this paper, regional checklists provide an account of the richness of ascidians in eastern Canada. Records of 58 ascidians resulted from reviewing 108 published sources, accessing data from two online databases, and collecting some common indigenous ascidian specimens. Analysis comparing the similarity of species among nine regions indicates that there is greater similarity in species composition between contiguous regions than between noncontiguous regions and suggests that there are four zoogeographic clusters in eastern Canada. Our checklists can inform managers and policymakers of the diversity of the ascidian taxa and can minimize taxonomic uncertainties of established nonindigenous and prospective invading species, for example, by identifying indigenous species that are congeners of nonindigenous species. The maintenance of checklists can be a valuable tool for the management of nonindigenous species as baselines to estimate changes in richness and to document the invasion status of nonindigenous species over time. For example, more importance can be placed on the spread of nonindigenous ascidians from one zoogeographic cluster to another than spread within the same cluster.
- Published
- 2017
4. A systematic review on the behavioural responses of wild marine mammals to noise: the disparity between science and policy
- Author
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Andrew J. Wright, Véronique Lesage, Alejandro D. Buren, Jack Lawson, Dominic J. Tollit, and Catalina Gomez
- Subjects
0106 biological sciences ,Noise ,Ecology ,010604 marine biology & hydrobiology ,Animal Science and Zoology ,Biology ,Interrupt ,010603 evolutionary biology ,01 natural sciences ,Ecology, Evolution, Behavior and Systematics - Abstract
Noise can cause marine mammals to interrupt their feeding, alter their vocalizations, or leave important habitat, among other behavioural responses. The current North American paradigm for regulating activities that may result in behavioural responses identifies received levels (RL) of sound at which individuals are predicted to display significant behavioural responses (often termed harassment). The recurrent conclusion about the need for considering context of exposure, in addition to RL, when assessing probability and severity of behavioural responses led us to conduct a systematic literature review (370 papers) and analysis (79 studies, 195 data cases). The review summarized the critical and complex role of context of exposure. The analysis emphasized that behavioural responses in cetaceans (measured via a linear severity scale) were best explained by the interaction between sound source type (continuous, sonar, or seismic/explosion) and functional hearing group (a proxy for hearing capabilities). Importantly, more severe behavioural responses were not consistently associated with higher RL and vice versa. This indicates that monitoring and regulation of acoustic effects from activities on cetacean behaviour should not exclusively rely upon generic multispecies RL thresholds. We recommend replacing the behavioural response severity score with a response/no response dichotomous approach that can represent a measure of impact in terms of habitat loss and degradation.
- Published
- 2016
5. An experimental study of how variation in deer density affects vegetation and songbird assemblages of recently harvested boreal forests
- Author
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Etienne Cardinal, Jean-Pierre Tremblay, Steeve D. Côté, and Jean-Louis Martin
- Subjects
Herbivore ,biology ,Ecology ,Taiga ,Animal Science and Zoology ,Ecosystem ,Vegetation ,Ecological succession ,Odocoileus ,biology.organism_classification ,Trophic cascade ,Ecology, Evolution, Behavior and Systematics ,Abies balsamea - Abstract
Intense browsing by abundant large herbivores can threaten the ecological integrity of ecosystems by inducing modifications in the structure and composition of vegetation that trigger trophic cascades affecting plant and animal communities. We investigated the relationships between density of white-tailed deer ( Odocoileus virginianus (Zimmermann, 1780)), forest succession after clear-cut, and songbird communities on Anticosti Island, Quebec, Canada. We hypothesized that lower deer densities would alter the trajectory of forest succession after clear-cutting and lead to a rapid recovery of habitat attributes favorable to songbirds associated with a dense complex shrub layer. Six years after establishing a controlled browsing experiment (0, 7.5, 15, and >27 deer·km–2) in recent clearcuts, reducing deer densities ≤7.5 deer·km–2initiated the restoration of balsam fir ( Abies balsamea (L.) Mill.) forests and increased the regeneration of paper birch ( Betula papyrifera Marshall). Increasing birch ground cover from 10% to 20% increased songbird total abundance, species richness, and diversity by 17%, 39%, and 31%, respectively. Alder Flycatcher (Empidonax alnorum Brewster, 1895) was only present at ≤7.5 deer·km–2and strongly associated with birch regeneration. The regeneration of browse-resistant plants such as white spruce ( Picea glauca (Moench) Voss) in some areas at high deer density favored the maintenance of many shrub-dependent songbirds but also species usually associated with forest canopy. Active management of deer populations in Canadian harvested boreal forests will mitigate losses in vegetation and songbirds caused by over-browsing.
- Published
- 2012
6. Feeding by Philoponella vicina (Araneae, Uloboridae) and how uloborid spiders lost their venom glands
- Author
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G. BarrantesG. Barrantes, W.G. EberhardW.G. Eberhard, and J.-L. WengJ.-L. Weng
- Subjects
biology ,Uloboridae ,technology, industry, and agriculture ,Zoology ,Venom ,macromolecular substances ,Anatomy ,equipment and supplies ,biology.organism_classification ,Predation ,behavior and behavior mechanisms ,Philoponella vicina ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics - Abstract
Feeding by uloborid spiders is unusual in several respects: cheliceral venom glands are absent; prey wrapping is extensive (up to several hundred metres of silk line) and severely compresses the prey; the spider’s mouthparts usually never touch the prey; and the entire surface of the prey is covered with digestive fluid. This paper presents observations on Philoponella vicina O. Pickard-Cambridge, 1899, which provide possible causal links between these traits. The spider begins ingesting soon after it wets the prey, gaining access to the prey’s interior through a broken cuticle that was broken during wrapping and by digestion of the prey’s membranes. The more abundant of the two types of wrapping lines is also digested, but the remaining shroud of wrapping silk is dense and filters digested prey particles. Robust setae on the palpal tarsus and the spread position of the anterior legs during feeding probably protect the spider from contact with the digestive fluid. Spiders extracted about 65% of the wet contents of the prey, but feeding was slow and involved substantial water evaporation. We propose that selection in uloborid ancestors to recover wrapping silk led to increased wetting of the prey’s surface and that compressive wrapping facilitated this wetting. These traits could have led to loss of the now superfluous cheliceral poison glands. Instituto Smithsoniano de Investigaciones Tropicales (STRI) Universidad de Costa Rica Smithsonian Tropical Research Institute, Panama, USA UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de Biología
- Published
- 2006
7. Bumblebee foraging and floral scent dimorphism: Bombus kirbyellus Curtis (Hymenoptera: Apidae) and Polemonium viscosum Nutt. (Polemoniaceae)
- Author
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Candace Galen, Peter G. Kevan, and National Research Council Canada
- Subjects
Polemonium viscosum ,biology ,Apidae ,Foraging ,Life Sciences ,biology.organism_classification ,Inflorescence ,Polemoniaceae ,Pollinator ,Botany ,Nectar ,Animal Science and Zoology ,Entomology ,Ecology, Evolution, Behavior and Systematics ,Bumblebee - Abstract
Plants of Polemonium viscosum have either sweet- or skunky-scented flowers. In this paper we examine the relationship between floral scent and visitation by the principal pollinator, Bombus kirbyellus. Field observations of nectar collecting bumblebee queens showed that bees visited plants with sweet-scented flowers significantly more often than those with skunky scent and tended to visit more flowers per inflorescence of sweet than of skunky scent. These observations agree with results from preference tests with captive bees foraging under controlled conditions on enclosed arrays of the two scent morphs. In experimental trials, bee orientation on the initial visit to the array and on visits between plants within the array favored sweet-scented inflorescences. Bees moved on the grid in such a way that skunky-scented nearest neighbors were undervisited, while sweet-scented flowers were visited more often than expected. In one set of trials, sucrose solution was added to flowers in order to compensate for natural standing crop variation. This treatment did not reduce bumblebee preference for the sweet scent morph nor alter the movement patterns of bees on the grid. Hence, in this system, floral visitation pattern appears to be influenced more strongly by scent than by nectar level.
- Published
- 1983
8. Hip glands in a field population of Microtus pennsylvanicus
- Author
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Rudy Boonstra and John H. Youson
- Subjects
stomatognathic system ,biology ,Zoology ,Animal Science and Zoology ,Field population ,Anatomy ,Microtus ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics ,Histological examination - Abstract
Hip glands are reported to be absent in Microtus pennsylvanicus. This paper presents histological evidence that they are present in field populations of this species in southern Ontario. Well-developed hip glands were found in 11 breeding males. No consistent relationship was found between the degree of development of the glands and breeding status in five females. We suggest that histological examination will reveal the presence of hip glands in other populations of this species as well.
- Published
- 1982
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