Natural Selection Vocbab APBIO

Unit 7? All about Speciation, Evolution, and stuff along the lines.

Homologous Structures

• Similarities in characteristics resulting from common ancestry

• They do not serve the same purpose in different animals

Analogous Structures

Different internal structures but similars functions due to adaptation to similar environments

Anatomical Structures

• Pelvis - Connects trunk to legs and supports upper body

• Ischium - Supports upper body, maintaining balance and erect posture

• Femur (thighbone) - Ability to stand and move

Vestigial Structures

• Remnants of structures that used to be functional in an ancestral species but have little to no function in the modern species

Geographic Seperation

• A population separated geographically accumulates differences, eventually resulting in a new species

• Once enough time is passed, the new species lost the ability to interbreed

Speciation

• The cessation of gene flow AKA lineage splitting

• Allows descendant lineages to evolve independently and acquire different traits

Clade

• An ancestor of ALL of its descendants

Fitness

• The ability of an organism to successfully survive TO reproduction and pass on traits

Zygote

• A cell that forms after the fusion of genetics

Post-zygotic Barriers

• Reduced Hybrid Viability-

  • The genes of different parent species may interact in ways that impair the hybrids development or survival

• Reduced Hybrid Fertility-

  • A hybrid can develop into a healthy adult, but it is sterile

• Hybrid Breakdown-

  • The hybrid of the 1st generation may be fertile, but when they mate with a parent species or one another, their offspring will be sterile

Microevolution

• A change in allele (traits) frequencies within a single species of population 

  • Natural selection, sexual selection, genetic drift, and gene flow

Macroevolution

• Large evolutionary patterns

Punctuated Equilibrium 

• Evolution occurs rapidly after a long stasis

Gradualism

• Evolution occurs slowly over hundreds, thousands, or millions of years

Divergent Evolution

• Groups with the same common ancestor evolve and accumulate differences, resulting in new species

Adaptive Radiation

• When a new habitat/niche becomes available, a new species CAN diversify rapidly

Convergent Evolution

• 2 different species develop similar traits despite having different ancestors (analogous traits)