Glossary
Adaptation
The process by which species change over time to better fit their environment, involving genetic, behavioral, or physiological modifications that enhance survival and reproduction.
Example:
A chameleon's remarkable ability to change its skin color to match its surroundings is a classic adaptation for camouflage, helping it avoid predators.
Allopatric Speciation
A type of speciation where a physical barrier, such as a mountain range or a river, separates two populations, preventing gene flow and leading to their independent evolution into distinct species.
Example:
The formation of the Grand Canyon led to allopatric speciation in the Abert's squirrel, creating the Kaibab squirrel on the North Rim and the Abert's squirrel on the South Rim.
Behavioral Adaptation
Changes in the actions or habits of a species that improve its survival and reproductive success within a specific environmental context.
Example:
Many bird species undertaking long-distance migrations to find warmer climates and abundant food sources during winter is a prime behavioral adaptation.
Divergence
The process by which two or more populations, often due to differing environmental pressures or isolation, accumulate distinct genetic and phenotypic traits over time.
Example:
Darwin's finches on the Galapagos Islands show clear divergence, with different beak shapes evolving on various islands based on the specific food sources available.
Evolution
The gradual change in the genetic makeup of a population over successive generations, driven by environmental pressures and leading to new species or altered traits.
Example:
The long-term process of whales evolving from land-dwelling mammals to fully aquatic creatures, losing their hind limbs and developing fins, is a profound example of evolution.
Genetic Adaptation
Changes in the DNA of a species that are passed down through generations, resulting in inherited traits that improve an organism's fitness in its environment.
Example:
The rapid development of antibiotic resistance in bacterial populations is a powerful example of genetic adaptation, allowing them to survive and thrive in the presence of antimicrobial drugs.
Genetic Diversity
The variety of genes within a species or population, which increases its resilience and capacity to adapt to environmental changes, diseases, or disasters.
Example:
A population of wild rice with high genetic diversity is more likely to contain individuals resistant to a new fungal blight, preventing a total crop failure.
Physiological Adaptation
Changes in the internal body functions or processes of an organism that enhance its ability to survive and thrive in its particular environment.
Example:
A desert fox having specialized kidneys that produce highly concentrated urine is a crucial physiological adaptation to conserve water in arid conditions.
Reproductive Isolation
A state where two populations can no longer interbreed and produce fertile offspring, effectively preventing gene flow between them and leading to their divergence into separate species.
Example:
If two groups of crickets develop distinct mating calls that only their own group recognizes, they will experience reproductive isolation, even if they live in the same field.
Survival of the Fittest
A principle stating that individuals with traits best suited to their environment are more likely to survive, reproduce, and pass on those advantageous genes.
Example:
In a harsh desert environment, a cactus with genes for storing more water will demonstrate survival of the fittest compared to one that stores less, especially during a prolonged drought.
Sympatric Speciation
A type of speciation where populations in the same geographic area stop reproducing due to non-physical barriers, such as different breeding times, habitat preferences, or mating behaviors.
Example:
Some apple maggot flies have undergone sympatric speciation by adapting to different host plants (apples vs. hawthorns), leading to distinct breeding seasons and reproductive isolation.