The " Origin of Species " was published nearly twenty years after Wagner's first account, but more relevant is the evidence of his ethological [ behavioural ] isolating mechanisms " but his inferences about geographical speciation were important insights gained by observation of insects in their natural habitats.
12.
An isolating mechanism between the two species may be the fact that " F . vesiculosus " normally reproduces sexually whereas " F . radicans " shows a much greater tendency to reproduce asexually, with detached fragments having the ability to take root and develop into new plants.
13.
:" It took more than 60 years after 1859 until the leading specialists . . . [ agreed ] that this geographical approach was the way to solve the problem of speciation . . . a new species may evolve when a population acquires isolating mechanisms while isolated from its parent population . ".
14.
:" The person who more than anyone else deserves credit for reviving an interest in the ecological significance of species was David Lack . . . It is now quite clear that the process of speciation is not completed by the acquisition of isolating mechanisms but requires also the acquisition of adaptations that permit co-existence with potential competitors ."
15.
Holley and Greenley ( 2005, p . 96 ) state that social context of certain resource conditions act as an element to create isolating mechanisms and quote Wernerfelt ( 1986 ) that tacitness ( accumulated skill-based resources acquired through learning by doing ) complexity ( large number of inter-related resources being used ) and specificity ( dedication of certain resources to specific activities ) and ultimately, these three characteristics will result in a competitive barrier.
