An example of such an introduction was the release of the highly toxic South American cane toad ( Bufo marinus) to the toad-free Australian continent in 1935. Although the impacts of introduced species often vary among ecosystems, the introduction of toxic prey into naГЇve predator faunas may become particularly destructive ( Phillips et al. Following similar anthropogenic introductions of invasive species, Australia, like smaller islands, has also suffered from the extinctions of numerous native species ( Flannery 19). For example, the accidental introduction of a novel predator, the brown tree snake ( Bioga irregularis), to the island of Guam has caused the extirpation of majority of the island's 25 resident bird species ( Wiles et al.

Moreover, such novel adaptations may make island biotas highly susceptible to anthropogenic introduction of invasive species ( Pimm et al. 2006 Whittaker and FernГЎndez-Palacios 2007 Calsbeek et al. Thus, island living may result in migrants acquiring significant novel physiological, behavioral, as well as morphological adaptations ( Blumstein and Daniel 2005 Aubret et al. Animals migrating to islands, however, often experience only a subset, or even a total lack of the selective regimes to which they have been subjected to on the mainland. Such coevolutionary interactions are, hence, one of the major processes responsible for global biodiversity ( Thompson 1999). Our study hence presents a clear link between genotype and phenotype, a critical step in understanding the evolution of phenotypic diversity.ДЄmong-species interactions form the foundation of adaptive evolution and the diversification of species. The transfections resulted in an approximate 3000-fold reduction in resistance to Bufalin in the Australian HEK293 cells compared to the AsianвЂ“African HEK293 cells, demonstrating the critical role of this minor mutation in providing Bufalin resistance. The phenotypic effect of the substitutions was investigated in human embryonic kidney (HEK) 293 cells stably transfected with the Australian and the AsianвЂ“African H1-H2 domains.

However, compared to the AsianвЂ“African varanids, the Australian varanids showed four-base-pair substitutions, resulting in the alteration in three of the 12 amino acids representing the H1-H2 domain. Sequencing of this domain revealed identical nucleotide sequences in four Asian as well as in three African varanids, and identical sequences in all 11 Australian varanids. Toad toxins, such as Bufalin target the H1-H2 domain of the О± 1 subunit of the sodium-potassium-ATPase enzyme. In contrast AsianвЂ“African varanids, which have coevolved with toads, are resistant to toad toxin. Since their introduction to the toad-free Australian continent cane toads ( Bufo marinus) have caused a dramatic increase in naГЇve varanid mortality when these large lizards attempt to feed on this toxic amphibian.

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