The "Hybrid Bridge" hypothesis: host shifting via plant hybrid swarms
Article Abstract:
The hybrid bridge hypothesis, which argues that plant hybrids facilitate shifting of herbivores to new plant hosts, was discussed. Current explanations of the mechanism for host shifting is based on preadaptation hypothesis, which involves preadaptation by an herbivore before it can make the shift to a new plant host, or at least a key mutation has to occur soon after shifting to ensure survival in the new host. The hybrid bridge hypothesis, on the other hand, considers the role of naturally occurring hybrid plants that morphologically, genetically and spatially bridge the gap between parental species and allow herbivores to shift hosts gradually.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1993
User Contributions:
Comment about this article or add new information about this topic:
Interactions between Abert's squirrel and ponderosa pine: the relationship between selective herbivory and host plant fitness
Article Abstract:
The dependence of Abert's squirrels, a highly selective and specialized herbivore, on its host ponderosa pine leads to deteriorating fitness levels and seed quality. Abert's squirrels also show a marked preference for certain specific individual ponderosa trees to use as sources of inner bark, and thus aid in their natural selection. The reductions in host fitness result from energetic constraints caused by the squirrel's feeding activities. Squirrels consume most of the upper crown of target trees, which are rich in photosynthetic tissues, and this retards growth and reproduction.
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1993
User Contributions:
Comment about this article or add new information about this topic:
Assessing functional explanations of host-specificity
Article Abstract:
A modification of some models for the evolution of host range or habitat specificity in parasite species is proposed. Mathematical equations expressing the conditions for specificity in terms of the proportion of dispersing parasites that find hosts were derived. The specificity conditions were simplified by assuming equilibrium state for the parasite population, and are then used to explain host-specificity. The proposed modification eliminates the need for difficult-to-measure parameters such as 'rate of encounter' and 'instantaneous mortality.'
Publication Name: The American Naturalist
Subject: Earth sciences
ISSN: 0003-0147
Year: 1992
User Contributions:
Comment about this article or add new information about this topic:
- Abstracts: Testing hypotheses about evolutionary change on single branches of a phylogeny using evolutionary contrasts. The evolution of dispersal in spatially and temporally varying environments
- Abstracts: Maintenance of genetic polymorphism: spatial selection and self-fertilization. Selection for overcompensatory plant responses to herbivory: a mechanism for the evolution of plant-herbivore mutualism
- Abstracts: Theoretical implications for the evolution of postsegregational killing by bacterial plasmids. On the evolution of masting behavior in trees: predation or weather?
- Abstracts: Can the variation in samara mass and terminal velocity on an individual plant affect the distribution of dispersal distances?
- Abstracts: The phylogenetic component of cooperative breeding in perching birds: a commentary. Comparative analyses of phylogenetic effects in the life-history patterns of iguanid reptiles