Let-7 miRNAs down-regulate the translation of Ras. Thus in the absence of the miRNAs, Ras is constitutively overproduced, contributing to tumorigenesis.

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#Id: 5738

#Unit 10. Ecological Principles

Elton’s hypothesis suggests there is a linear correlation between species richness and community services

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#Id: 5739

#Unit 10. Ecological Principles

Paul and Ann Ehrlich (1981) proposed an alternative called the rivet hypothesis Some species play a small but critical role in keeping the plane, the community, airborne, while other species do not

TLS Online TPP Program

#Id: 5740

#Unit 10. Ecological Principles

 Brian Walker (1992) proposed the Redundancy hypothesis Species that play the same roles in a community can compensate for each other if some are lost under particular conditions

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#Id: 5741

#Unit 10. Ecological Principles

Keystone hypothesis

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#Id: 5742

#Unit 10. Ecological Principles

Idiosyncratic hypothesis Community services change as the number of species increases or decreases, but that the direction of change is not predictable

TLS Online TPP Program

#Id: 5743

#Unit 10. Ecological Principles

Ecotones - An ecotone is a zone of junction or a transition area between two biomes (diverse ecosystems).