SUBDIVISIONS OF BIOLOGY
Biology can be divided into fields of study in a variety of ways, depending upon the questions being asked. Because ofthe breadth of knowledge in modern biology fields of specialization have developed in which an individual scientist can concentrate on his specialty and keep abreast of pertinent developments. Although most modern biologists are specialists in particular fields, many rely on other scientific disciplines such as physics, chemistry, and geology in attempting to understand certain biological phenomena. For example, detailed studies of bioluminescence—the light produced by organisms such as fireflies—require a knowledge of complex biochemical processes. Studies of the evolution of specific groups of plants or animals that are frequently found as fossils require a background in geology.
Some scientific investigators restrict their research to one or a few groups of organisms. For this reason the specialty of many biologists becomes the group of organisms that they study. Such designations can be general in nature, such as zoology (the study of animals), botany (the study of plants), or bacteriology (the study of bacteria). Or they can be more specific, as the following:
Arachnology: spiders, mites, scorpions
Herpetology: reptiles and amphibians
Nematology: nematode worms
Protozoology: protozoans (single-celled animals)
Anatomy and morphology.
Anatomists and morphologists study the structure of organisms. Some morphological research compares homologous (similar in origin) or analogous (similar in function) structures among different species to establish phylogenetic relationships. Other studies may be carried out to determine the function or mode of operation of an anatomical feature. Histology (study of tissue structure) and cytology (study of cell structure) are specialized areas of morphology. Many morphological studies are useful in human or veterinary medicine.
A physiologist studies the functions of the organs and tissues of plants and animals. A cell physiologist investigates processes at the subcellular level. At the other extreme physiological research focuses on how systems (such as circulatory, digestive, and reproductive) function. Many physiological studies are intimately associated with morphology.
Naming organisms and establishing their relationships to one another have been a fundamental development of biology since people first became aware of the wealth of plant and animal types in the world. The importance of this endeavor continues today and is carried out by scientists who work with museums and many universities. Taxonomicrules can be developed for, and principles of classification can be applied to, all groups of plants or animals. Because of the large number of species, however, most classification specialists limit their efforts to particular groups of organisms.
Using the standard rules established by Linnaeus, today’s taxonomists classify species based on shared attributes and the closeness of their evolutionary relationships. Each species is given a generic name (genus), which is capitalized, and a specific name (species), which is not. Besides genus and species, several higher taxonomic levelsare internationally recognized. The higher levels indicate the phylogenetic relationships, the degree to which different species have diverged from each other during the course of evolution. Thus, closely related groups are placed in the same taxonomic category at all levels, whereas distantly related forms are placed together only at the higher taxonomic levels.
Modern classification has resulted in the discovery of taxonomic techniques that permit new interpretations of phylogenetic relationships among organisms. The biological classification scheme serves the vital function of statingwhat the phylogenetic relationships are believed to be, based on current knowledge. The taxonomic placement of particular species, genera, or groups of higher levels will be continually challenged as scientific progress is made.
Embryology and developmental biology.
Developmental biologists seek to describe and understand the processes that govern the growth and development oforganisms. Included within the field are studies of embryological development of plants or animals and the natural phenomenon of regeneration in which removed cells, tissues, or entire structures of an organism grow back. Research of this nature has direct applicability to the medical profession through the development of principles that give insights into human developmental processes.