Unit 9 honors bio

Adaptive Radiation

• Definition: The rapid diversification of a single ancestral species into a wide variety of forms adapted to different environments or ecological niches.
  
  

• Example: Darwin's finches in the Galápagos Islands, which evolved into different species with specialized beaks suited for various types of food sources.

Allopatric Speciation

• Definition: Speciation that occurs when populations of a species become geographically isolated, leading to genetic divergence.
  
  

• Example: A river that splits a population of squirrels, and over time, the two groups evolve into separate species due to lack of gene flow.

Barriers to Mating

• Behavioral: Differences in mating behaviors or rituals that prevent interbreeding.
  
  

  • Example: Different bird species have distinct songs that attract only their species.
    
    

• Geographic/Habitat: Physical separation between populations, like mountains or rivers, preventing interbreeding.
  
  

  • Example: A mountain range separating two populations of the same species.
    
    

• Temporal: Species mate at different times of the year, preventing cross-breeding.
  
  

  • Example: Two species of frogs in the same area but one breeds in the spring and the other in the fall.
    
    

• Mechanical: Differences in reproductive organs that prevent mating.
  
  

  • Example: Flowers with different shapes that only specific pollinators can access.
    
    

• Gametic: Differences in the compatibility of sperm and egg cells between species.
  
  

  • Example: In some species of sea urchins, the sperm cannot fertilize the egg because of differences in surface proteins.
    
    

Cladogram

• Definition: A diagram used to show relationships among species, based on shared derived characteristics (synapomorphies).
  
  

• Derived Characteristics: Traits that are found in a species and its descendants, but not in its ancestors.
  
  

Coevolution

• Definition: The process where two or more species influence each other's evolution, often in response to reciprocal selective pressures.
  
  

• Example: The evolution of flowers and their pollinators, such as bees evolving to pollinate certain types of flowers.
  
  

Convergent Evolution

• Definition: When unrelated species evolve similar traits due to similar environmental pressures.
  
  

• Analogous Structures: Traits that have similar functions but arise from different evolutionary paths.
  
  

• Example: The wings of bats and birds, both serve the function of flight but evolved independently.
  
  

Divergent Evolution

• Definition: When two species with a common ancestor evolve different traits due to different environmental pressures.
  
  

• Homologous Structures: Structures that are similar due to shared ancestry, even if they serve different functions.
  
  

• Example: The forelimbs of humans, bats, and whales—though they have different functions, they share a common skeletal structure.
  
  

Evolution

• Definition: The process by which populations of organisms change over generations through variations in traits and natural selection.
  
  

Extinction

• Definition: The end of a species or group of species.
  
  

• Micro or Macro?: Extinction is considered a form of macroevolution because it affects entire species or groups.
  
  

Fossil Record

• Definition: The collection of preserved remains or traces of organisms from past geological ages.
  
  

• Importance: Provides evidence of the history of life on Earth and the evolution of species.

Genetic Drift

• Definition: Random changes in allele frequencies in a population, especially in small populations.
  
  

• Example: A random event (like a natural disaster) drastically reducing a population's size, leading to genetic changes.

Genomics/DNA

• Definition: The study of genomes, which are the complete set of DNA within an organism, including all its genes.

Geographic Isolation

• Definition: Physical separation of populations that can lead to speciation.
  
  

• Example: An island separating from a mainland population, leading to two distinct species over time.

Gradual Adaptation

• Definition: Slow and steady changes in a species over time due to natural selection.

Hybridization

• Definition: The process of interbreeding between two different species, often producing hybrid offspring.
  
  

• Example: The mule, a hybrid of a horse and a donkey.

Macroevolution

• Definition: Large-scale evolutionary changes that occur over geologic time, resulting in the formation of new species and higher taxonomic groups.

Mass Extinction

• Definition: A widespread and rapid extinction of many species in a relatively short period of time.
  
  

• Comparison to Background Extinction: Mass extinctions are more sudden and widespread compared to background extinctions, which occur gradually over time.
  
  

• Current Mass Extinction: The sixth mass extinction is primarily caused by human activity (e.g., habitat destruction, climate change).
  
  

Microevolution

• Definition: Small-scale evolutionary changes within a population, typically due to natural selection, genetic drift, or gene flow.
  
  

Migration/Gene Flow

• Definition: The movement of genes between populations due to the migration of individuals, leading to changes in allele frequencies.
  
  

Mutations

• Definition: Changes in the DNA sequence that can lead to new genetic variations.
  
  

• Can Mutations Increase in a Population?: Yes, if they provide a selective advantage or are passed down through reproduction.
  
  

• When Can Mutations Be Passed On?: Only if they occur in the gametes (sperm or eggs).
  
  

• Are Mutations Always Harmful?: No, some mutations are neutral or even beneficial.
  
  

Natural/Artificial Selection

• Natural Selection: The process by which organisms with traits better suited to their environment tend to survive and reproduce.
  
  

• Artificial Selection: The human-driven process of selecting organisms with desired traits for breeding.
  
  

• Example of Artificial Selection: Breeding dogs for specific traits like size or temperament.
  
  

Phenotype

• Definition: The observable characteristics or traits of an organism, influenced by both its genotype and the environment.
  
  

Phylogenetic Tree

• Definition: A diagram that shows the evolutionary relationships between species based on shared common ancestry.
  
  

Phylogeny

• Definition: The evolutionary history and relationship of a species or group of species.
  
  

Population

• Definition: A group of organisms of the same species living in the same area and capable of interbreeding.
  
  

Punctuated Equilibrium

• Definition: A theory that suggests species remain relatively unchanged for long periods, punctuated by brief periods of rapid evolution.
  
  

• Proposed by: Eldredge & Gould.
  
  

Reproductive Isolation

• Definition: Barriers that prevent different species from interbreeding and producing viable offspring.
  
  

Speciation

• Definition: The formation of new and distinct species due to factors like genetic divergence and reproductive isolation.
  
  

• Two Main Drivers of Speciation:
  
  

  • Geographic Isolation (e.g., through geographic barriers)
    
    

  • Reproductive Isolation (e.g., different mating behaviors or times)
    
    

Species

• Definition: A group of organisms that can interbreed and produce fertile offspring.
  
  

Sympatric Species

• Definition: Species that live in the same geographic area but avoid interbreeding due to other forms of reproductive isolation.
  
  

Taxonomy

• Linnaeus: Developed the binomial nomenclature system for naming species.
  
  

• Proper Naming: Species names should be italicized, with the genus capitalized and the species lowercase (e.g., Homo sapiens).
  
  

• The Six Kingdoms:
  
  

  • Animalia, Plantae, Fungi, Protista, Archaea, Bacteria
    
    

• Three Domains:
  
  

  • Eukarya, Archaea, Bacteria
    
    

Temporal Isolation

• Definition: Species that reproduce at different times, preventing interbreeding.
  
  

• Example: Two species of frogs breeding in different seasons.
  
  

Three Major Sources of Changes in Allele Frequency:

1. Mutations: Random genetic changes that introduce new alleles.
   
   

2. Gene Flow: The movement of alleles between populations through migration.
   
   

3. Genetic Drift: Random changes in allele frequency, especially in small populations.