7th Grade Science Guide

7.5: Changes in Species 3 Dimensions & Progressions

Unit 6

Cross Cutting Concepts ● CCC 1: Patterns ● CCC 2: Cause & Effect

to changes in environmental conditions. Traits that support successful survival and reproduction in the new environment become more common; those that do not become less common. Thus, the distribution of traits in a population changes. ● The collection of fossils and their placement in chronological order (e.g., through the location of the sedimentary layers in which they are found or through radioactive dating) is known as the fossil record. It documents the existence, diversity, extinction, and change of many life forms throughout the history of life on Earth. ● Anatomical similarities and differences between various organisms living today and between them and organisms in the fossil record, enable the reconstruction of evolutionary history and the inference of lines of evolutionary descent. ● Comparison of the embryological development of different species also reveals similarities that show relationships not evident in the fully-formed anatomy.

K-2

3-5

9-12

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Some living organisms resemble organisms that once lived on Earth. Fossils provide evidence about the types of organisms and environments that existed long ago. Differences in characteristics between individuals of the same species provide advantages in surviving and reproducing. Particular organisms can only survive in particular environments.

Natural selection occurs only if there is variation in the genes and traits between

organisms in a population. Traits that positively affect survival can become more common in a population. ● Evolution results primarily from genetic variation of individuals in a species, competition for resources, and proliferation of organisms better able to survive and reproduce. Adaptation means that the distribution of traits in a population, as well as species expansion, emergence or extinction, can change when conditions change.

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