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Rabbits and hares
Learn all about rabbits and hares and the differences and similarities between the two.
Book
sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares
1. Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2. In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52% from the first to the second litter. From the first to the second litter, litter size increased 122%, offspring body mass increased 130%, and offspring RHF length increased 112%. Dam FCM concentrations were inversely related to litter size (r² = 0·19), to offspring birth mass (r² = 0·32), and to offspring RHF length (r² = 0·64). 3. In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1-2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessful-stressed dams (those that failed to give birth to live young) and stressed dams had 837% and 214%, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37% lighter and 16% smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r² = 0·57) and RHF (r² = 0·52). 4. This is the first study in a free-ranging population of mammals to show that elevated, predator-induced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output.
Journal Article
From process to pattern: how fluctuating predation risk impacts the stress axis of snowshoe hares during the 10-year cycle
Predation is a central organizing process affecting populations and communities. Traditionally, ecologists have focused on the direct effects of predation—the killing of prey. However, predators also have significant sublethal effects on prey populations. We investigated how fluctuating predation risk affected the stress physiology of a cyclic population of snowshoe hares (Lepus americanus) in the Yukon, finding that they are extremely sensitive to the fluctuating risk of predation. In years of high predator numbers, hares had greater plasma cortisol levels at capture, greater fecal cortisol metabolite levels, a greater plasma cortisol response to a hormone challenge, a greater ability to mobilize energy and poorer body condition. These indices of stress had the same pattern within years, during the winter and over the breeding season when the hare: lynx ratio was lowest and the food availability the worst. Previously we have shown that predator-induced maternal stress lowers reproduction and compromises offspring's stress axis. We propose that predator-induced changes in hare stress physiology affect their demography through negative impacts on reproduction and that the low phase of cyclic populations may be the result of predator-induced maternal stress reducing the fitness of progeny. The hare population cycle has far reaching ramifications on predators, alternate prey, and vegetation. Thus, predation is the predominant organizing process for much of the North American boreal forest community, with its indirect signature—stress in hares—producing a pattern of hormonal changes that provides a sensitive reflection of fluctuating predator pressure that may have long-term demographic consequences.
Journal Article
Hare
\"In times past reckoned to be the 'most lascivious and most melancholy' of mammals, the hare was also believed to never close its eyes, occasionally to grow horns, and to be able to change its gender. It was credited in early medicine with the most curative properties of any animal. But the hare is in fact as remarkable for its actual characteristics and behaviour as for the intriguing myths that have developed around it. In this book, Simon Carnell examines how the hare has been described, symbolized and depicted, as well as valued for its fur, flesh and exceptional speed.\"--BOOK JACKET.
Book
Recombinant Myxoma Virus in European Brown Hares, 2023–2024
Recombinant myxoma virus has emerged in European brown hares (Lepus europaeus), causing increased deaths associated with swollen eyelids, head edema, and dermatitis at face, legs, and perineum. Introduction may date back as far as September 2020. As of August 2024, the disease is spreading radially from the Germany-Netherlands border area.
Journal Article
Of lemmings and snowshoe hares: the ecology of northern Canada
Two population oscillations dominate terrestrial community dynamics in northern Canada. In the boreal forest, the snowshoe hare (Lepus americanus) fluctuates in cycles with an 8–10 year periodicity and in tundra regions lemmings typically fluctuate in cycles with a 3–4 year periodicity. I review 60 years of research that has uncovered many of the causes of these population cycles, outline areas of controversy that remain and suggest key questions to address. Lemmings are keystone herbivores in tundra ecosystems because they are a key food resource for many avian and mammalian predators and are a major consumer of plant production. There remains much controversy over the role of predation, food shortage and social interactions in causing lemming cycles. Predation is well documented as a significant mortality factor limiting numbers. Food shortage is less likely to be a major limiting factor on population growth in lemmings. Social interactions might play a critical role in reducing the rate of population growth as lemming density rises. Snowshoe hares across the boreal forest are a key food for many predators and their cycles have been the subject of large-scale field experiments that have pinpointed predation as the key limiting factor causing these fluctuations. Predators kill hares directly and indirectly stress them by unsuccessful pursuits. Stress reduces the reproductive rate of female hares and is transmitted to their offspring who also suffer reduced reproductive rates. The maternal effects produced by predation risk induce a time lag in the response of hare reproductive rate to density, aiding the cyclic dynamics.
Journal Article
Complete Mitogenomes of Xinjiang Hares and Their Selective Pressure Considerations
Comparative analysis based on the mitogenomes of hares in Xinjiang, China, is limited. In this study, the complete mitochondrial genomes of seven hare samples including four hare species and their hybrids from different environments were sequenced, assembled, and annotated. Subsequently, we performed base content and bias analysis, tRNA analysis, phylogenetic analysis, and amino acid sequence analysis of the annotated genes to understand their characteristics and phylogenetic relationship. Their mitogenomes are circular molecules (from 16,691 to 17,598 bp) containing 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and a control region, which are similar with other Lepus spp. worldwide. The relative synonymous codon usage analysis revealed that the adaptation of Lepus yarkandensis to its unique arid and hot environment might be associated with synthesizing amino acids like alanine, leucine, serine, arginine, and isoleucine and the terminator caused by the different usage of codons. Further, we utilized the MEME model and identified two positive selection genes (ND4, ND5) in Lepus tibetanus pamirensis and one (ND5) in L. yarkandensis that might be important to their adaptation to the plateau and dry and hot basin environments, respectively. Meanwhile, Lepus tolai lehmanni and Lepus timidus may have evolved different adaptive mechanisms for the same cold environment. This study explored the evolutionary dynamics of Xinjiang hares’ mitochondrial genomes, providing significant support for future research into their adaptation mechanisms in extreme environments.
Journal Article