Your text reviews basic genetics and patterns of evolutionary change. However, genetics and evolution interact in complex ways. Much of this interaction occurs in the course of gene regulation, development, and growth. The interactions between genetic elements and the developing body result in phenotypes. These phenotypes, or organisms, then participate in various evolutionary processes. This Virtual Exploration goes beyond the basics to look at the role of regulation and development in the creation of organisms.

In the pages that follow, you can explore gene regulation, gene expression, induction, and how these processes lead to the development of different body patterns. Finally, we will put all these concepts together to understand Developmental Systems Theory.

Gene Regulation
http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/ge/m5/s4/index.htm

Think about: Recall the process of protein synthesis (covered in chapter 2). Where do different enzymes and proteins act to move the process along?

Epigenetics and Gene Expression
http://genome.wellcome.ac.uk/doc%5Fwtd020756.html

Think about: How can gene expression or gene silencing affect an organism?

Induction: How Tissues Communicate during Development
http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/an/m13/s2/index.htm

Think about: How do tissues affect one another during development?

Pattern Formation in Animal Development
http://www.mhhe.com/biosci/esp/2001_gbio/folder_structure/an/m13/s3/index.htm

Think about: How do changes in the expression of certain genes alter the structure of an organism's body?

Developmental Systems Theory
The concepts you have just reviewed come together in Developmental Systems Theory (Oyamam et al. 2001) The three main points of this theory are:

1. Joint determination by multiple causes: Every trait is produced by the interaction of many developmental resources. The interaction of the gene and the environment dichotomy is only one way to think about the evolutionary processes.
2. Development as construction: Neither traits nor representations of traits are transmitted to offspring. Instead, traits are made- constructed- during the development of the organism.
3. Evolution as construction: Evolution is not a matter of organisms or populations being molded by their environments. Instead, evolution occurs as organism-environment systems change over time.

Given our reviews of the processes of evolution combined with what we have covered here, answer these three questions:

1			Why does it matter that every trait is produced by the interaction of many developmental resources?
2			If development is construction, then does the DNA really have "instructions" for this construction?
3			Finally, what does it mean that evolution is organism-environment systems changing over time?