Biological Sciences
Plant Timeline Evolution
The plant timeline evolution refers to the gradual development and diversification of plant life over millions of years. It encompasses the emergence of key plant groups, such as bryophytes, ferns, gymnosperms, and angiosperms, and their adaptation to various environmental conditions. This evolutionary process has led to the vast array of plant species that exist today, each with unique characteristics and ecological roles.
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3 Key excerpts on "Plant Timeline Evolution"
No longer available |Learn more- Rene Fester Kratz(Author)
- 2011(Publication Date)
- For Dummies(Publisher)
Part IV The Wide, Wonderful World of Plants: Plant BiodiversityIn this part . . .Plants appeared on Earth long ago and have evolved many complex and wondrous forms, from tiny floating pond weeds to the mighty redwood tree. Just as you can draw a family tree for your family, scientists draw family trees, that show relationships among all the living things on earth. In this part, I introduce the amazing diversity of plant groups found in the family tree of life on Earth.
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Chapter 13 Changing with the Times: Evolution and Adaptation In This ChapterUnderstanding the sources of genetic changeExamining plant evolutionChecking out plant adaptationsLFiguring Out the Fundamentals of Evolutionife on Earth is constantly changing in response to environmental changes. Life, including plants, migrated from the oceans to the land, dinosaurs have come and gone, and modern humans evolved and spread over the face of the Earth. Biological evolution is the process that leads to changes in the species of life on Earth. Biological evolution occurs through a combination of genetic changes and natural selection. This chapter presents the fundamentals of biological evolution, examples of how to measure evolution in populations, and an exploration of some of the amazing adaptations resulting from plant evolution.Evolution is change that occurs over time. Biological evolutionmore specifically refers to changes in living organisms that occur over time. Life on Earth is constantly changing, usually in ways so small you’d hardly even notice. But if you look over huge spans of geological time — millions or billions of years — you can see the big changes that result from biological evolution, from the migration of life from the ocean to the land to the rise and fall of the dinosaurs. During this history of life on Earth, plants have changed from strictly aquatic organisms to simple land plants that reproduced by spores to the more dramatic cone-bearing and flowering plants that grow all around you today.
eBook - PDFEvolutionary Ecology of Plant-Plant Interactions
An Empirical Modelling Approach
- Christian Damgaard(Author)
- 2005(Publication Date)
- Aarhus University Press(Publisher)
7. Evolution of plant life history Trade-offs and evolutionary stable strategies If relevant genetic variation is available in a plant population, the proc- ess of natural selection will cause evolution (Darwin 1859), i.e., the phys- iology, morphology and life history of the plant population will adapt to the present abiotic and biotic environment. Since evolution depends on the process of natural selection, the type of evolutionary changes are limited by the mechanisms of natural selection and often, but certainly not always (Lewontin 1970), this means that the evolutionary changes should be explained at the level of the fitness of the individual plant. A plant with a given amount of resources at a certain point in time may allocate its resources to different purposes determined by the evolved life history of the plant and impulses from the environment. For example, an annual plant will usually allocate all its resources to re- production at the end of the growing season, whereas a perennial plant only can allocate a fraction of its resources to reproduction (e.g. Harper 1977). Some of the resources of the perennial plant need to be stored to survive during harsh periods, e.g. during a drought or a winter period. The perennial plant is said to make a trade-off between reproduction and survival, and since both features are important for the individual fitness of the plant this trade-off will be under selective pressure. The characteristic life history of a specific plant species will to a large extent often be determined by the way natural selection has shaped the morphological and physiological features underlying the various trade- offs. Other trade-offs that are being selected to increase the fitness of the individual plant at its particular environment include the allocation between male and female sexual structures, and the allocation between structures that will increase growth, e.g. stems and leaves, and a general storage of resources (e.g. Harper 1977).
eBook - PDF- David Briggs, S. Max Walters(Authors)
- 2016(Publication Date)
- Cambridge University Press(Publisher)
The first two models represent phyloge- netic cascades. Different shading indi- cates the different clades within each phylogeny. (From Forister & Feldman, 2011.) Reprinted with permission. Flowering plant evolution 358 Timescales and timetrees: the role of fossils and molecular clocks Turning to another key issue, phylogenetic trees require an evolutionary timescale. This is provided by evidence from the fossil record and the use of molecular methods. Historically, Zuckerkandl & Pauling (1965) proposed that ‘for any given protein, the rate of molecular evolution is approximately constant over time in all lineages, or in other words, that there exists a molecular clock’. If this is true it follows that such a clock can be used to ‘reconstruct phylogenetic relationships among organisms’ and estimate the timing of ‘species divergence’ (Graur & Li, 1999). The notion of a molecular clock is also predicted by the neutral theory of DNA evolution (Kimura, 1987). If mutations are neutral, by definition they will not affect fitness, and, over time, they will accumulate in a lineage in clock-like fashion at the rate of neutral mutations. A number of statistical dating techniques have been devised that are called relaxed clock models (for details see Rutschman, 2006; Wheeler, 2012). The molecular clock in itself does not provide concrete dates: it is necessary to have independent evidence from fossils, or other dateable events to calibrate the clock. After calibration, phylogenetic trees become ‘timetrees’ (Kenrick, 2011). Universal or local clocks? Graur & Li (1999) conclude that while there is no evidence for universal clocks, ‘there may be many local clocks that tick regularly for groups of closely related species’. Considering the evidence from plant studies, Stuessy (2009) confirms that ‘no precise clock exists . . . some genes just mutate faster than others’ (see Arbogast et al., 2002; Donoghue & Smith, 2004; Rodriguez Trelles, Tarrio & Ayala, 2004).
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