Unit 6 Lesson 2: Resources Affect Evolution Flashcards
competition
when organisms living in the same community use the same limited resources, but those resources are not enough to fill the needs of every individual organism
struggle for existence
the competition for vital resources between members of a population
intraspecific competition
competition between two or more individuals of the same species
Example of Intraspecific competition
two males of a species might compete for the same mate, or one grizzly bear might catch a salmon upstream making it harder for the bears downstream to find food.
Exmaple of Interspefic competition
multiple species might compete for scarce water during a drought or for habitat in a deforested location.
interspecific competition
competition between two or more individuals of different species
Direct competition
competition between two or more individuals where the individuals fight one another for the same resource
Example of direct competiton
Typically, the larger and more aggressive individuals or species win the resources they need. For example, the two antelopes above are fighting each other for mates. This direct interaction is the hallmark of this type of competition.
Indirect competition
competition between two or more individuals where the individuals use the same resource but do not interact with each other directly
Example of Indirect competition
Larger plants, for example, overshadow smaller plants, thus gaining more of a necessary resource (light).
In most cases what does competition lead to
In most cases, competition leads to a new stable population in which species have either competed successfully, decreased in number, or become extinct in that area.
fitness
how well an individual survives and produces offspring in its environment
What does an organism’s fitness determine
Over time, an organism’s fitness determines which organisms competing for scarce resources adapt and evolve or become extinct.
An organism’s fitness is linked to its
environment
An organism’s fitness is linked to its environment. Give example
In the ocean, a shark is an apex predator, perfectly fit for its environment. Now imagine that same shark trying to survive in a desert. The shark could not possibly live in that environment. What if the shark remained in the ocean, but had fewer fish to eat? Could it still be successful?
apex predator
a predator that has no predator that preys upon it in an ecosystem
What does the fitness of an individual depend on
The fitness of an individual depends on both the individual’s traits and how well those traits help the individual survive and reproduce in a specific environment.
Most organisms reproduce in large numbers, but only a small number of organisms survive long enough to reproduce. The process by which some organisms adapt and survive is called
natural selection
natural selection
the process that results in an organism having favorable adaptations to its environment, which are passed on through reproduction, thus changing the genetic makeup of future generations
Those that survive have the most favorable adaptations, why is that
Those that survive have the most favorable adaptations to their environments because they have traits—such as physical strength, speed, or intelligence—that help them to successfully compete for resources. In the long run, this kind of competition can impact adaptations, migrations, and extinctions.
impact of a flood
A flood can vastly increase the number of locations where mosquitoes can lay their eggs. This can lead to an increase in the number of mosquitoes available. As mosquitoes are an important food source for many animals, such as birds, bats, and turtles, those species will compete less for food. One possible outcome of a flood, therefore, is an increase in the number of birds, bats, and turtles in the area.
gene flow
When a migrating individual transfers its genetic material from one population to another, that is called gene flow. Gene flow is an important source of genetic diversity.
impact of a hurricane
A hurricane can destroy coastal swamps and other protected coastline habitats where juvenile fish and other aquatic animals can stay safe while they grow to maturity. This can make it much harder for those animals to survive because they become more vulnerable to predators. Meanwhile, predators such as alligators and carnivorous fish have greater access to food and thus compete less for food, and the number of some species of marine animals will shrink.
impact of a drought
A drought in the plains can make it hard for grasses to survive. This will also impact the survival of animals who depend on the grasses. Grazing animals will face more competition. Some may die. Others may migrate to regions with more food availability, effectively removing their genetic material from the original ecosystem, while adding it to their new ecosystem.
