Most horse (equine) breeds have been selectively bred for specific features, such as speed, or strength. Like all other species on the planet, the horse has undergone changes because of natural selection over time. A modern example is the breed of horses living on Sable Island, about 150 km east of Nova Scotia. About 250 years ago, records show that several horses that look like the ones in the photograph below were released onto the island. Today horses on Sable Island look very different. Over the last 250 years various horse breeds have been introduced to Sable Island, however, none of them resemble the pony sized animals living there today. Their appearance is a result of environmental stresses and natural selection in their new surroundings.
Big Question: How might one breed of modern horse evolve if the breed were to exist in the wild, without interaction with humans?
1. Complete a timeline showing the evolution of horses over the past 54 million years from Hyracotherium to Equus. Include how traits like size, hooves, teeth shape and composition have changed over time. Link the changes to changes in the environment and niche (for example, what conditions resulted in longer limbs or shorter muzzles).
2. Select one breed of modern horse, such as the Arabian, Morgan, Shire or Quarter horse. Outline three of the traits that that breed has been selectively bred for by humans and how these traits have been influenced by how the breed is used by humans.
3. Next, a smallish herd of horses of your selected breed is "lost" and left to reproduce and fend for themselves for the next 250 years.
o Describe the area in which your breed is lost and the factors that will influence the evolution of your breed such as climate, other species present, types of vegetation, availability of resources etc.
o Indicate how your think your breed would evolve if it was "lost" in an area without humans (like the Sable Island Ponies were lost) by specifically describing how the traits you indicated would change in the descendants and why.
o Use evidence from other breeds or the ancestral horses to support your ideas!
o Make clear connections to at least one mechanism (other than "natural selection") that will drive this change o use unit specific vocabulary to indicate and support the types of selection (such as competition, genetic drift or stabilizing selection) occurring and your understanding of the concepts of evolution.
4. Provide a "before" and "after" picture of your breed. You will have to draw the "after" picture yourself.