Natural Selection and Adaptive Evolution

An individual's contribution to the next generation's gene pool.

Favors individuals with one extreme of a trait, shifting the population's average trait in that direction.

Favors individuals at both extremes of a phenotypic range, disadvantaging those with intermediate traits.

Favors intermediate phenotypes and reduces variation, maintaining the status quo.

The process where traits that increase reproductive success become more common in a population.

The change in a population's traits over time, due to natural selection enhancing favorable traits.

Observable characteristics of an organism, directly influenced by the genotype.

An organism's genetic makeup, indirectly influencing its observable traits.

A type of selection where multiple alleles are maintained in a population because they are advantageous in different situations or combinations.

When heterozygous individuals have a higher fitness than both homozygous individuals for a specific trait, leading to the maintenance of multiple alleles.

The fitness of a phenotype depends on its prevalence in the population, leading to oscillating allele frequencies.

A process where individuals with specific traits are more likely to secure mates, often leading to differences between males and females.

Competition within the same sex for access to mates, often involving physical conflict or dominance displays.

One sex, usually females, choosing mates based on specific traits such as appearance or behavior.

The idea that female preference for male traits may evolve because these traits signal a male's genetic quality.

Organisms are not perfectly adapted due to constraints like limited variations, historical constraints, compromises, and random events.

Natural selection can only act on traits already present in a population, not creating new ones.

Evolution modifies existing structures, adapting them for new purposes.

Adaptations often involve trade-offs, where a beneficial trait for one function might be detrimental for another.

Defines a species as a group of populations that can interbreed in nature and produce viable, fertile offspring but cannot do so with other groups.

Transfer of alleles between populations, maintaining the gene pool of a species.

A group of populations whose members can interbreed in nature and produce viable, fertile offspring, but cannot do so with members of other such groups.

When biological barriers prevent interbreeding between different species, stopping them from producing viable, fertile offspring.

Factors that prevent fertilization by interfering with mating attempts, successful mating, or blocking fertilization.

Factors that affect hybrid offspring after fertilization, resulting in issues like developmental errors, infertility, or reduced survival.

It cannot be applied to fossils, asexual organisms, or species that occasionally interbreed.

Classifies species based on their body shape and structure, applicable to both sexual and asexual organisms.

Aristotle's concept of a ladder of nature, where species were arranged in a fixed hierarchy with humans at the top.

Linnaeus's system for naming species using a two-part name, with the first part being the genus and the second being the species.

Preserved remains or traces of past organisms, often found in sedimentary rock layers.

Layers of sedimentary rock that reveal the order in which organisms lived.

The study of fossils, providing insights into the history of life on Earth.

Cuvier's theory that sudden catastrophic events caused extinctions and shaped Earth's features.

Hutton and Lyell's idea that Earth's features are formed by slow, continuous processes.

Lamarck's idea that body parts used frequently become stronger, while those not used weaken and disappear.

Lamarck's theory that traits gained during an organism's lifetime are passed on to offspring.

The ability of bacteria to survive and reproduce in the presence of antibiotics that would normally kill them.

Overusing antibiotics creates an environment where only resistant bacteria survive and reproduce, making them the dominant strain.

Natural selection doesn't create new traits, but selects for traits that already exist in a population.

Bacteria reproduce quickly, allowing natural selection to shape their evolution at a faster pace.

Similarities between organisms due to common ancestry, hinting at evolutionary relationships.

Shared bone structures between different species despite different functions, suggesting common ancestry.

Similarities in embryonic development despite adult differences, indicating shared ancestry.

Remnants of features present in ancestors but reduced or non-functional in modern species.

Similarities at the genetic level, revealing shared ancestry even between distantly related organisms.

Evolution of similar features in distantly related species due to similar environments.

Features with similar function but different evolutionary origins, not due to shared ancestry.

Features with shared ancestry but different functions, indicating evolutionary relationships.

Homologous features have shared ancestry but possibly different functions (like forelimbs), while analogous features have similar function but different evolutionary origins (like wings).

Evolution modifies existing structures and functions over time, leading to diversity and adaptation.

The idea that all life on Earth is interconnected through a series of common ancestors.

Darwin's five-year expedition aboard the HMS Beagle, where he observed and collected specimens from various regions, leading to his groundbreaking theory of evolution.

Darwin's shift from classifying species to investigating the processes that led to their adaptations, particularly how traits help organisms survive and reproduce in specific environments.

Inherited characteristics that enhance an organism's ability to survive and reproduce in its environment, shaping how species evolve over time.

A group of finches with diverse beak shapes and feeding behaviors, observed by Darwin on the Galápagos Islands, providing evidence for adaptation and natural selection.

Darwin's term to describe how all organisms are related through a common ancestor and have diverged over time, accumulating changes as they adapted to different environments.

A single species from which all living organisms are descended, highlighting the shared commonality of life on Earth.

The process where humans selectively breed organisms to accentuate desired traits, often resulting in domesticated species with distinct characteristics.

Organisms produce more offspring than their environment can support, leading to competition for resources and a selective pressure for survival and reproduction.

Evidence for evolution from observed shifts in populations, such as how soapberry bugs adapted their beak length to feed on different fruit types.

The change in beak length of soapberry bugs to efficiently feed on different fruit types, demonstrating natural selection favoring traits that improve feeding efficiency.

Darwin's work established the concept of natural selection as the mechanism behind evolution, providing evidence and explanations for the diversity of life.

Darwin's work revolutionized our understanding of life, shifting the perspective from a fixed hierarchy to a dynamic system of change and adaptation.

Evolutionary theory is supported by an overwhelming amount of evidence from various fields, including fossil record, anatomical similarities, molecular data, and direct observations.

The preserved remains or traces of past organisms, providing evidence for evolution by showing how species have changed over time.

Fossils that exhibit traits of both ancestral and descendant groups, bridging the gap between them.

The study of species' geographic distributions, influenced by continental drift and other factors.

The gradual movement of Earth's continents over millions of years, impacting species distributions.

The study of species on islands, often showing unique adaptations and relationships to mainland counterparts.

A well-supported explanation for a wide range of observations and phenomena, continually tested and refined.

A trait that enhances an organism's ability to survive and reproduce in a specific environment.

The process of forming new species from existing ones, often due to reproductive isolation.

Formation of new species due to geographic isolation of populations.

Formation of new species within the same geographic location, often due to ecological or behavioral differences.

Change in the genetic makeup of a population over time, leading to diversity and adaptation.