Ecology: Biology of Interaction. 5.24. Life Forms of Organisms
Life form is a stable complex of adaptations to a particular mode of life. Their study began with Theophrastus, who divided plants into trees, shrubs, and herbs; later this approach was developed in greater detail.
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5.23. Adaptations of Organisms
D. Shabanov, M. Kravchenko. Ecology: Biology of Interactions Chapter 5. Autecology and Fundamentals of Environmental Science
5.25. Autecology: Summary
5.24. Life forms of organisms A life form is a stable complex of adaptations to a certain way of life. Within different large taxa, similar adaptive types, or life forms, are found, reflecting adaptations to specific environmental conditions or lifestyles. For example, marine mammals (whales, dolphins, seals) and fish have similar adaptations to an aquatic lifestyle, despite their distant relationship. Such similarity, which arose independently in different evolutionary lines, is called convergence. The study of plant life forms was initiated by Theophrastus, who divided plants into trees, shrubs, and herbs. A. Humboldt described them in more detail. The most famous classification of plant life forms was developed by C. Raunkiær (1905), based on the location of renewal buds during the unfavorable season (winter or drought): — Phanerophytes (Ph) — renewal buds are located higher than 25 cm above the soil surface. These include trees, shrubs, vines, and epiphytes. — Chamaephytes (Ch) — renewal buds are located below 25 cm above the soil surface, but above the snow cover level. These include subshrubs and some herbaceous plants. — Hemicryptophytes (H) — renewal buds are located at the soil surface level or slightly below. These include most temperate climate herbaceous plants. — Cryptophytes (K or Cr) — renewal buds are located below the soil surface or underwater. These include bulbous, rhizomatous, and aquatic plants. — Therophytes (T) — survive the unfavorable season in the form of seeds. These include annual plants. [IMG_1] Fig. 5.24.1. Classification of plant life forms according to Raunkiær. Arrows indicate the location of renewal buds: Ph — phanerophytes, Ch — chamaephytes, H — hemicryptophytes, G — geophytes (a subclass of cryptophytes), HH — helophytes and hydrophytes (a subclass of cryptophytes), Th — therophytes
Classifications of life forms have also been developed for animals, but they are less unified than for plants. For example, the following life forms are distinguished for terrestrial vertebrates: arboreal, terrestrial (runners, jumpers, burrowers), subterranean, aquatic, semi-aquatic, aerial, and others. Vicariants are species belonging to the same life form that occupy similar ecological niches in different parts of their range. For example, in the steppes of Eurasia, the prairies of North America, and the pampas of South America, the ecological niche of large herbivorous ungulates is occupied by different but similar species in terms of lifestyle (European bison and American bison, horses and kulans, llamas). Life forms are the result of convergent evolution – the independent emergence of similar adaptations in different evolutionary lineages under the influence of similar environmental conditions. The study of life forms allows for a better understanding of the relationship between an organism's structure and its lifestyle, as well as the identification of general patterns of adaptation to different environmental conditions.
Self-check questions: 1. What is a life form? 2. What is Raunkiaer's classification based on? 3. What are the five main groups identified by Raunkiaer? 4. Who are vicars? 5. What is convergent evolution?
5.25. (Addendum) Metabolism, Energy, and Information Exchange