Williams features a bottle system for studying the fundamentals of evolution. What distinguishes living things from dead and nonliving things? No single characteristic is enough to define what is meant by "life. How can we make sense of the living world?
During this session, a systematic approach to biological classification is introduced as a starting point for understanding the nature of the remarkable diversity of life on Earth. One characteristic of all life forms is a life cycle — from reproduction in one generation to reproduction in the next.
This session introduces life cycles by focusing on continuity of life in the Animal Kingdom. In addition to considering what aspects of life cycles can be observed directly, the underlying role of DNA as the hereditary material is explored. What is a plant? One distinguishing feature of members of the Plant Kingdom is their life cycle. In this session, flowering plants serve as examples for studying the plant life cycle by considering the roles of seeds, flowers, and fruits. A comparison to animal life cycles reveals some surprising similarities and intriguing differences.
What causes variation among a population of living things? How can variation in one generation influence the next generation? In this session, variation in a population will be examined as the "raw material" upon which natural selection acts.
Why are there so many different kinds of living things? Comparing species that exist today reveals a lot about their relationships to one another and provides evidence of common origins. This session explores the theory of evolution: change in species over time. Alfred Russel Wallace noted the similarities and differences between nearby species and those separated by natural boundaries in the Amazon and Indonesia. Independently they came to the same conclusion: over generations, natural selection of inherited traits could give rise to new species.
Use the resources below to teach the theory of evolution in your classroom. Genes are units of hereditary information. A gene is a section of a long molecule called deoxyribonucleic acid DNA.
Genetics is the study of genes and how traits are inherited—or passed down—from one generation to the next. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image genetic variation In many species, special genetic variations give animals a camouflaged appearance to blend in with their environment, like this Catalpa Sphinx moth Ceratomia catalpae which uses its textured wings to blend in with a tree's bark.
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Related Resources. View Collection. We describe some of the repercussions of differences in body size among vertebrates and ways in which these can be allowed for.
In addition, a variety of evolutionary processes can produce non-adaptive differences between organisms. One way of distinguishing between these and adaptations is to investigate adaptive trends in phylogenetically different groups of species.
Abstract It has sometimes been suggested that the term adaptation should be reserved for differences with a known genetic basis.
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