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Mutualism Parasitism Continuum
The hypothesis or paradigm of Mutualism Parasitism Continuum postulates that compatible host-symbiont associations can occupy a broad continuum of interactions with different fitness outcomes for each member. At one end of the continuum lies obligate mutualism where both host and symbiont benefit from the interaction and are dependent on it for survival. At the other end of the continuum highly parasitic interactions can occur, where one member gains a fitness benefit at the expense of the others survival. Between these extremes many different types of interaction are possible. The degree of change between mutualism or parasitism varies depending on the availability of resources, where there is environmental stress generated by few resources, symbiotic relationships are formed while in environments where there is an excess of resources, biological interactions turn to competition and parasitism. Classically the transmission mode of the symbiont can also be important in predicting w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red King Hypothesis
The Red King hypothesis contrasts with the Red Queen hypothesis, where mutualistic and cooperative interactions favor the fitness of a set of individuals through slow evolution, as opposed to having competitive interactions or having an " arms race". The hypothesis posits that individuals from different communities can establish positive interactions for long periods of time when there is a great benefit for both parties, also through mutual help, individuals from different species (communities) can share different tasks to build a niche ( Black Queen hypothesis), which avoid spending energy in competing and increasing their resilience over environmental stress. The types of interaction between species determine how fast they coevolve: parasites and their hosts are thought to co-evolve more rapidly, while partners in a mutualistic relationship are thought to evolve more slowly. The Red King effect drives slower-evolving species to obtain a higher proportion of long-term benefits ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Queen Hypothesis
The Red Queen hypothesis is a hypothesis in evolutionary biology proposed in 1973, that species must constantly adapt, evolve, and proliferate in order to survive while pitted against ever-evolving opposing species. The hypothesis was intended to explain the constant (age-independent) extinction probability as observed in the paleontological record caused by co-evolution between competing species; however, it has also been suggested that the Red Queen hypothesis explains the advantage of sexual reproduction (as opposed to asexual reproduction) at the level of individuals,Bell, G. (1982). The Masterpiece Of Nature: The Evolution and Genetics of Sexuality. University of California Press, Berkeley, 378 pp. and the positive correlation between speciation and extinction rates in most higher taxa. Origin In 1973, Leigh Van Valen proposed the hypothesis as an "explanatory tangent" to explain the "law of extinction" known as "Van Valen's law", which states that the probability of e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Queen Hypothesis
The Black Queen hypothesis (BQH) is reductive evolution theory which seeks to explain how natural selection (as opposed to genetic drift) can drive gene loss. In a microbial community, different members may have genes which produce certain chemicals or resources in a "leaky fashion" making them accessible to other members of that community. If this resource is available to certain members of a community in a way that allows them to sufficiently access that resource without generating it themselves, these other members in the community may lose the biological function (or the gene) involved in producing that chemical. Put another way, the black queen hypothesis is concerned with the conditions under which it is advantageous to lose certain biological functions. By accessing resources without the need to generate it themselves, these microbes conserve energy and streamline their genomes to enable faster replication. Jeffrey Morris proposed the Black Queen hypothesis in his 2011 PhD ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Interaction
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species ( interspecific interactions). These effects may be short-term, like pollination and predation, or long-term; both often strongly influence the evolution of the species involved. A long-term interaction is called a symbiosis. Symbioses range from mutualism, beneficial to both partners, to competition, harmful to both partners. Interactions can be indirect, through intermediaries such as shared resources or common enemies. This type of relationship can be shown by net effect based on individual effects on both organisms arising out of relationship. Several recent studies have suggested non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structures. However, it remains unclear whether these findin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
