Unit 7 Lesson 5: Competitive Advantage Flashcards
adapted
a term used to describe a species that has evolved characteristics and/or behaviors that can be inherited from generation to generation that allow the species to better survive and reproduce in a given environment
Natural selection
Natural selection occurs when organisms that are better adapted to their environment survive and produce more offspring. The process of natural selection is what leads to evolution
evolution
a change in the characteristics and/or behavior of a species or population over time
niche
a term that describes the habitat and resources used by a species or population along with its interactions with other species within an ecosystem
By looking at the birds’ DNA, which is almost identical, scientists discovered that the finches came from one common ancestor from the mainland and then adapted to the different islands. Differmce in their beaks
The beak of each finch is specialized for the type of food that is available in its specific niche, or habitat.
Based on DNA evidence, it has been shown that all of the Galápagos Island finches evolved from a finch species common on the mainland of South America. The evolution of such a wide variety of related species from a single ancestral species is known as
adaptive radiation
adaptive radiation
an evolutionary phenomenon in which populations of a single ancestral species become isolated and adapt to different ecosystems, evolving adaptations specific for that environment, which results in the evolution of several different but related species from a single ancestral one over a relatively short amount of time from a geological perspective
. According to Darwin, individuals within a population have variation. In other words, every individual is somewhat unique. You have different characteristics and behaviors compared to others. Darwin reasoned that some individuals have a competitive advantage due to their specific characteristics and behaviors. What happens next
This competitive advantage allows these individuals to survive better in the environment and reproduce more often. This increases the number of offspring in the next generation that inherit these adaptations. Over time and with the accumulation of different adaptations, these populations can evolve into new species.
One observation they made was that the birds ignored other species when they were near. Since each species of bird is adapted to its particular niche, the birds do not have to compete with each other for resources. This phenomenon is known as
resource partitioning, and it is very common in nature.
resource partitioning
a phenomenon in evolutionary biology in which species living in the same ecosystem will use different food, water, and shelter resources in order to avoid competition between each species
resource partitioning example
To make this principle clearer, imagine a scenario in which two species live in the same ecosystem and initially compete for the same food resources. Because of that competition, neither species tends to survive and reproduce as well as they would on their own. Now, imagine if some individuals in this ecosystem begin to use other food resources. Because of the lack of competition, these individuals survive better and reproduce more. Over time, this process continues until the two species no longer use the same resources.
Natural slection in the GRants
In 1977, Daphne Major experienced a major drought, and the small, soft seeds of the birds’ diet were eaten quickly, leaving the birds with only large, tough seeds. The Grants reported many deaths of birds with small beaks since they were not able to eat the large seeds. The next year, the Grants reported that the offspring from the birds that survived were larger in size and had larger beaks. The birds with bigger beaks that survived had a competitive advantage over the other birds. The Grants also discovered that females mated with males with beaks that were similar in size.
The Grants continued their research and monitoring of the medium ground finches, including one year when there was above average rainfall. The vegetation took over the land, and the vines took over the plants that produced the large seeds. This left an abundance of small soft seeds. The birds that had adapted to the larger seeds were not able to pick up the small seeds to eat and many died. The birds with smaller beaks were more successful and survived. The Grants discovered that natural selection had once again affected the offspring of the birds in the next generation.
Over time a species, a group of organisms that can interbreed and produce fertile offspring, can evolve separately from other species. This is called
speciation
Before this research, the prevailing idea in evolution was that evolution by natural selection took many generations to produce significant differences in populations. How did this idea change
The Grants were able to show that even in one generation, strong environmental pressures can produce changes in a population that can alter the species’ evolutionary path.
speciation occurs both artificially and naturally. What artifcal speciation like
Artificial speciation by human intervention has resulted in new animal and plant species, selected for specific traits. New pathogenic species of infectious agents have developed in response to antibacterial or antiviral agents.
Natural speciation, on the other hand, predates human interaction. Speciation has occurred in the process of evolution by a number of different causations:
natural selection, mutation, genetic drift, and gene flow.
Often speciation takes a very long time, but sometimes the process is much faster.
One example is adaptive radiation, a form of natural selection.
Darwin’s finches provide a classic example of the evolution of species from a single common source into a variety of different, related species, in a process called
adaptive radiation
Adaptive radiation can occur after mass extinctions. Elaborate
Adaptive radiation can occur after mass extinctions. Mammals flourished after the extinction of the dinosaurs, freeing many new resources. Mammals also evolved new traits, such as new molar shapes, which enabled them to consume additional food resources. Others colonized new habitats, such as the Darwin’s Finches of the Galapagos, specializing different food sources.
Adaptive radiation can be distinguished by several features:
- It is a rapid process. Speciation occurs quickly.
- The descendent populations have a common ancestor.
- Environmental conditions change, such as new resources or niches open or new challenges or stresses arise.
Describe how the process of natural selection occurs.
Natural selection occurs when organisms that are better suited to their environment are able to survive and reproduce more often compared to individuals that do not have the more successful adaptations.
How did the different species of finches arrive at the Galapagos Islands?
One species of bird arrived and adapted to different niches on the islands.
The birds are all the same species of birds.
The genes of the birds had a mutation, creating different species of birds.
Several different birds arrived from the mainland at about the same time.
- One species of bird arrived and adapted to different niches on the islands.
- The genes of the birds had a mutation, creating different species of birds.
DNA shows that the birds are almost identical, suggesting a common ancestor had adapted to the different areas of the islands.
The birds were thought to come from the mainland and then adapted to the different islands over time.
Imagine that the population of finches have experienced drought conditions for several years, which has dramatically increased the proportion of larger-beaked birds in the population. Now, the weather shifts from drought to rainy conditions, and the food resources on the island shifts from large seeds to small seeds, which are harder for larger-beaked birds to eat. Describe what would happen to this population of finches over time in these conditions using the term competitive advantage.
The larger beaks of the bird are no longer a competitive advantage when the island receives more rain. With an abundance of small seeds, smaller-beaked birds now have a competitive advantage, allowing them to survive better and reproduce more. This generates more offspring with smaller beaks. Over time, this flips the population to having more smaller-beaked birds compared to larger-beaked birds.
Describe what happened after the drought occurred on Daphne Major in 1977.
The drought left hard and larger seeds that were difficult for the birds with smaller beaks to pick up. These birds did not survive, and the birds with the larger beaks did. The next season, the new birds that were born had larger bodies and larger beaks.
