A Comparative Review of the Vascular System in Seed Plants and Humans

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A comparative review of the vascular system in seed plants and humans

In the evolutionary tree of life, all biotic organisms are believed to have derived from a common ancestor. The organisms falling under the eukaryotic kingdom of Plantae are known to have arisen in the same time period as those in the eukaryotic kingdom of Animalia—the Paleozoic era, about 500 million years ago (MYA) (Raven et al., 2008). Despite their chronological resemblance, their evolutionary diversity is especially great in their most advanced organisms—humans and seed plants. One key system that illustrates this diversity is the vascular system (or the cardiovascular system in humans). The vascular system of the respective lines of organisms show similarities in origin, food and water circulation, while at the same time showing differences in disease prevention and environmental dependency.

Genetic mapping has confirmed the origin of plants to be from an ancestral alga. Modern phylogenetics categorizes green algae and higher order plants into a new kingdom called Viridiplantae. As Viridiplantae organisms evolved, they eventually sprawled from freshwater and came to evade land. Horizontal gene transfer (HGT) and selective pressures caused a large diversification and thus gave rise to three types of land plants (Figure 1): bryophytes, tracheophytes, and seed plants (*Puigbò et al., 2009; Raven et al., 2008). Bryophytes, which include liverworts, hornworts, and mosses arose 450 MYA, and thus began the terrestrial colonization of plants. Tracheophytes first appeared about 420 MYA are plants specialized in vascularization—they were among the first plants to tissue that allowed for the distribution of material throughout their bo...

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...Life’ in the thicket of the phylogenetic forest. BMC Journal of Biology 8:59.

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Figures1-3 are courtesy of the McGraw-Hill Companies (Raven, 2008)

Figure 4 is courtesy of Journal of Obesity (Iacobellis, 2006)

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