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Complex Traits

Author(s): Nancy Moreno, PhD.

Dogs — A Model Organism for Modern Genetics

Activity 1: Slides 2–10. You will need to project slides 2–8 during different stages of Activity 1. Slides 9–10 are for optional use or viewing.


Students explore variation among dog breeds, and compare variation within domesticated dogs to variation within wolves. Students also determine relationships among the dog and its closest relatives using a phylogenetic tree. 

From the tiny, long-haired Pekingese to the tall, short-haired Great Dane, domestic dogs show immense variety in their sizes, shapes, coat colors and textures, and behaviors. Selective breeding by humans for desirable genetic changes or mutations generated this variability. Today, more than 400 distinct breeds of dogs are recognized.

Because of its wide range of characteristics, the domestic dog (Canis familiaris) has become an important model for modern genetic studies. However, most of this diversity is found only between dog breeds. The characteristics of individuals within a particular dog breed are very uniform—genetically and in appearance. In other words, dogs are homogeneous in their appearance (phenotype) and genetic makeup (genotype) within breeds, and are phenotypically and genetically heterogeneous among or between breeds. This pattern of variability, in which particular traits are accentuated within breeds, results from inbreeding (breeding of close relatives).

Funded by the following grant(s)

Science Education Partnership Award, NIH

Gene U: Inquiry-based Genomics Learning Experiences for Teachers and Students
Grant Number: 5R25OD011134

Robert Wood Johnson Foundation

Using Learning Technology to Build Human Capital
Grant Number: 57363