Phylogenetic Relationships Between The Gellatia Lizards Geography Essay

The Canary Islands are an archipelago of seven different islands: Lanzarote, Fuerteventura, Gran Canaria, Tenerife, Gomera, Palma and Hierro ( Thorpe et al. , 1995 ) . These islands are volcanic islands, whose beginnings can be explained by the theory of home base tectonics ( Thorpe et al. , 1995 ) . This theory states that the Earth is made up of many little home bases that are skiding comparative to each other on top of more hot and heavy stuff, the home base on which the Canary Islands sit moved over a “ hot topographic point ” which gave rise to the volcanic islands ( Thorpe et al. , 1995 ) .

Plate tectonics and C dating can besides bespeak the age of the islands and it was found that Lanzarote is the oldest island while Hierro is the youngest ( Thorpe et al. , 1995 ) . A species of lizard, Gallotia galloti, has seven different populations each populating a different island ( Thorpe et al. , 1995 ) . These populations are isolated allopatrically ( Thorpe et al. , 1993 ) . Allopatric populations are 1s that are separated by a geographical barrier, which is the ocean in this instance, and as a consequence diverge from the hereditary population. The Canary Islands wholly formed individually, and are non connected to each other or to the mainland ( Thorpe et al. , 1995 ) . This means that the lizards that managed to scatter onto each of these islands are, in some manner, different to each other and to the hereditary population on the mainland because of Allopatric isolation. The differences in these populations can be showed on phyletic trees. Phylogenetic trees can be drawn utilizing geographical, morphological and molecular informations.

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A phyletic tree based ( Fig 1 ) on the geographics of the islands can demo precisely how these lizards dispersed from the mainland onto each island. From the hereditary population on the mainland a few beings moved to the closest islands. Because Lanzarote is the oldest island it was the first island to be colonized and the new isolate lizards so speciated into G. stehlini. The following species dispersed onto the following closest island, where Allopatric isolation caused the speciation of G. atlantica. Then some of G. atlantica so dispersed onto the island of Tenerife, where they speciated into G. galloti. Then some of G. galloti from the island of Tenerife dispered onto the island of Palma and so later to the island of Gomera. The population of Gallotia lizards of Gomera so dispersed to the outer most island of Hierro.

The Biography of these lizards can give an indicant of the evolutionary mechanisms that lead to their speciation. The chief advantage of utilizing geological phyletic trees is that it is really easy and speedy to utilize. It may non be the most accurate but the weight of it being so easily to utilize makes it a good pick.


Differences in morphological fluctuation can be influenced by different environmental conditions ( Thorpe et al. , 1995 ) . Morphologic differences between the islands every bit good as on the island Tenerife include differences in scalation forms, coloring every bit good as organic structure size ( Thorpe et al. , 1995 ) . Variations in organic structure size can be associated with the environmental conditions on each island, with more favourable environments back uping larger organic structure sizes ( Thorpe et al. , 1995 ) . Variations in coloring material on the island Tenerife is owing to sexual choice and natural choice ( Thorpe et al. , 1995 ) . A phyletic tree ( Fig 2 ) based on morphology shows that from the hereditary population on the mainland, some diverged to G. stehlini and from the population of G. stehlini some beings diverged to go G. atlantica and G. galloti on the island Tenerife. From the G. galloti population on Tenerife some diverged to Palma and some to Gomera. From Gomera the population diverged to the island Hierro.

One of the jobs sing the survey of morphology is that we may be looking at a population of species that are highly morphologically similar such as these lizzards. In contrast, DNA sequences are different though. Using Deoxyribonucleic acid has the ability to happen a immense figure of different characters such as the place of base braces. Therefore, with this facet being taken into history, DNA is superior to morphology.

It is a great trade less expensive to utilize morphology than Deoxyribonucleic acid. This makes morphology superior to DNA, nevertheless DNA engineering becomes less expensive and faster all the clip, so this advantage to morphology is going less of import.


The molecular differences in the different populations of the lizards of the Canary Islands can be used to find their evolutionary relationship every bit good as the evolutionary procedures that lead to speciation ( Thorpe et al. , 1995 ) . It is the most utile and true representation of the existent relationship of beings because it takes into history the familial differences between the species ; all the base brace between the different populations all have an equal opportunity of mutating, therefore the rate of mutant the different populations is reasonably changeless ( Thorpe et al. , 1994 ) . The sum of differences between the populations can be used to build a phyletic tree of these lizards, with big values bespeaking populations that are genetically distant from each other and little values bespeaking populations that are genetically closer to each other. From the phyletic tree ( Fig 3 ) it can be seen that from the hereditary population on the mainland G. stehlini was the first to diverge, followed by G. atlantica. Then the population from north Tenerife branched of the hereditary population which so branched into G. galloti population on Palma.

By uniting the phyletic trees constructed from geological, morphological and molecular informations we can build a phyletic tree that is a really close representative of the existent evolutionary relationship between the lizard populations of the Canary Islands.


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