The Endangered Gray Wolf
Gray wolves used to be found all across North America from northern Mexico to Greenland. Their population is now endangered due to hunting and extermination. In 1960, the only wolves remaining in the lower 48 states were small populations in Minnesota.

The Relocation of the Gray Wolf
​The gray wolf was added to the  Endangered Species List in 1974. In 1995, the U.S. Fish and Wildlife Service (FWS) relocated a small number of gray wolves from Canada to Yellowstone National Park in Wyoming. The population thrived and has increased to several hundred individuals in the Yellowstone area. Biologists continue to research the effects of the wolf reintroduction on the Yellowstone ecosystem. One of the reasons ecologists thought that Yellowstone would be a good place for the gray wolf, is because Yellowstone was being overrun by Elk!
 
Consequences to the Ecosystem
Once the wolves were relocated to Yellowstone, the wolves had plenty of elk to eat. The wolf packs helped to reduce elk population. This was beneficial to the ecosystem, because when elk numbers get too high, the ecosystem cannot provide enough plants for the elk to eat and thousands starve during hard winters.

• More wolves led to less elk. -->   Less elk led to more plants.  -->    More plant led to more herbivores (plant-eaters).   --> More herbivores led to more small predators.

ALSO...

• More wolves led to less elk --> Less elk led to more plants. --> More plants (like the willow and cottonwood) helped to protect stream water quality and stream bank integrity. --> Better water led to an increase in trout population.

 
 Conservation Efforts Saved the Gray Wolf from Possible Extinction Today there are more than 5,500 wolves in the continental United States. The gray wolf has been taken off of the Endangered Species List. The wolf population is carefully monitored and guarded in some states to ensure the wolf population continues to thrive.
 
What is a Predator?
Predators kill and feed on other organisms.
 
Predation includes

• animals eating other animals (carnivore-herbivore interactions or carnivore-carnivore interactions)
• animals eating plants (herbivore-producer interactions).

 
 Predation has resulted in the co-evolution of predator strategies—more efficient ways to catch prey—and prey strategies—better ways to escape the predator. We see evidence of these strategies when analyzing the "Survivorship Curve" for a given species.  

​Survivorship Curve

• Survivorship is the proportion of individuals of a species within a population that survive to a particular age (stage of their life-cycle)
• In type I survivorship, as exemplified by large mammals, The young survive well and die when they get old.
• In type III survivorship, the probability of death is greatest early in life DUE TO PREDATION, and those individuals that avoid early death subsequently have a high probability of survival.
• Limiting Factors (such as competition and predation) effect the number of individuals in a population.

 

NATURAL SELECTION

• An efficient predator exerts a strong selective force on its prey, and over time, the prey species may evolve some sort of countermeasure that reduces the probability of being captured. The countermeasure that the prey acquires, in turn, may act as a strong selective force on the predator.
• An efficient predator exerts a strong selective force on its prey, and over time, the prey species may evolve some sort of countermeasure that reduces the probability of being captured. The countermeasure that the prey acquires, in turn, may act as a strong selective force on the predator.
• Adaptations related to predator–prey interactions include predator strategies (pursuit and ambush) and prey strategies (plant defenses and animal defenses).
• New traits arise randomly in a population as a result of mutation, and the traits may persist under natural selection.
•  The countermeasure that the prey acquires, in turn, may act as a strong selective force on the predator. 

Predator Strategies

• Pursuit Remember that any trait that increases hunting efficiency  for a predator is likely to persist in the population over many generations. These predators usually have large brains ( in comparison to body size) so that they can process information quickly during the pursuit of prey. Predators must be FASTER,  STRONGER and  SMARTER than their prey.
• Ambush is another effective way to catch prey.  Predators use camouflage to remain unnoticed by the prey until it is close enough to attach!. Predators lure the unsuspecting prey and then ambush.

Defensive Adaptations of Plants

• Plants cannot escape predators by fleeing, but they possess adaptations that protect them from being eaten.
  • They must defend them selves by other means like possessing ...
    • spines
    • thorns
    • tough leathery leaves
    • thick wax on leaves
    • chemicals  

Defensive Adaptations of Animals

• Running away / hiding
• Mechanical defenses (claws, quills, shells…)
• Safety in numbers - Some animals live in groups—a herd of antelope, colony of honeybees, school of anchovies, or flock of pigeons. This social behavior decreases the likelihood of a predator catching one of them unaware; the group has many eyes, ears, and noses watching, listening, and smelling for predators
• Chemical defenses are common among animal prey. The South American poison arrow frog has poison glands in its skin.
  • Some insects developed the an ability to tolerate milkweed toxins. As a result, they can eat milkweeds without being poisoned, and they accumulate the toxins in their tissues, making themselves toxic to predators
• Camouflage - Some animals blend into their surroundings to hide from predators.
  • The animal’s behavior often enhances such cryptic coloration.