Evolution Exam

Stratigraphy

The study of rock layers and how they’re arranged

Lamarck’s theory of evolution

Organisms can change during their lifetime and pass those changes onto their offspring

Two parts of Lamarck’s theory

Use and Disuse: used body parts get larger and stronger, unused body parts get smaller or disappear

Inheritance of Characteristics: traits gained during an offspring’s lifetime are passed onto offspring

Darwin’s theory of evolution

Organisms with helpful characteristics survive and reproduce more, causing those traits to become more common over time

Adaptation

An inherited trait that increases survival or reproduction

Artificial selection

Humans choose which organisms reproduce

Homologous structures

Structures with similar anatomy but different functions that indicate common ancestry

Vestigial structures

Structures that have little to no current function but demonstrate evidence of evolution from when it was useful

Branch points

Points where lines split on the tree; represents a common ancestor

Derived characteristics

A newly evolved trait that appears in a lineage but was not present in their common ancestors

Convergent Evolution

Unrelated species have similar traits due to similar environments

Analogies

Structures that have the same function but did not evolve from a common ancestor

Biogeography

The study of where plants and animals live on earth and why they live there

Pangea

Ancient supercontinent

Endemic Species

Species only found in one specific geographic area (ex: kangaroos)

Microevolution

Small changes in a population’s genetic makeup over time

Gene pool

All the genes/alleles in a population

Allele frequency

How common an allele is in the gene pool

Allele frequency equation

p + q = 1

Genotype frequency equation

p² + 2pq + q² = 1

Conditions for Hardy-Weinberg Equilibrium

• No mutations

• Random mating

• No natural selection

• Large population size

• No gene flow

Sexual selection

Traits evolve based on mating success

Sexual dimorphism

Males and females of the same species have different behaviors and/or appearances beyond reproductive organs

Intrasexual selection

Members of the same sex compete for attention from a potential mate

Intersexual selection

One sex chooses a specific mate from the opposite sex based on desired traits

Types of natural selection

Directional, disruptive, and stabilizing

Directional selection

One extreme trait is favored

Disruptive

Both extremes are favored

Stabilizing

Average trait is favored

Genetic drift

Random changes in allele frequencies

Two types of genetic drift

Founder effect and bottleneck effect

Founder effect

Small group starts a new population; new group is so small and carries a fraction of the original genetic diversity

Bottleneck effect

A sudden event changes the genetic makeup of the population at random

Gene flow

Movement of alleles between populations

Speciation

The process where one species evolved into 2 or more species

Reproductive isolation

Mechanisms that prevent species from breeding

Two types of reproductive isolation

Prezygotic barriers and postzygotic barriers

Prezygotic barriers (before fertilization)

• Habitat isolation

• Temporal isolation

• Behavioral isolation

• Mechanical isolation

• Gametic isolation

Postzygotic barriers (after fertilization)

• Reduced hybrid viability

• Reduced hybrid fertility

Three species concepts

Biological species, morphological species, and ecological species

Biological species concept

A species is a group of organisms who can breed and produce fertile offspring

Morphological species concept

Species are defined by their physical appearance

Ecological species concept

Species are defined by their niche (role in environment)

Hybrid breakdown

First generation of hybrids is healthy and fertile but future generations are weak and/or sterile

Allopatric speciation

Speciation caused by geographic isolation

Sympatric speciation

Speciation occurring in the same geographic area

Sympatric speciation causes

• Polyploidy

• Sexual selection

• Habitat differentiation

Polyploidy

Organisms gain extra sets of chromosomes

Habitat differentiation

Populations in the same area start using different habitats or resources

Hybrid zones

Areas where 2 different species meet and mate

Outcomes of hybrid zones

• Reinforcement: hybrids have low fitness and species separate

• Fusion: gene flow is so high that species merge into one

• Stability: hybrid zone continues and species neither merge nor separate

Punctuated Equilibrium

Theory that species have long periods of little to no evolutionary change, interrupted by bursts of rapid evolution

Gradualism

Theory that species diverge slowly and steadily over long periods of time

Macroevolution

Large-scale evolutionary change over long periods of time

Protocells

Simple cell-like structures surrounded by vesicles/membranes that were precursors to cells

Self-replicating RNA

Likely the first genetic material that could store info, copy itself, and act as an enzyme

Radiometric dating

A technique used to date rocks/fossils using radioactive isotopes

Plate tectonics

Earth’s crust is divided into moving plates that change the Earth’s surface over time

Adaptive radiation

Rapid evolution of many new species from one ancestor due to open ecological niches; often occurs after mass extinctions

Heterochrony

Evolutionary change in the rate or timing of development

Exaptation

Trait evolves for one function but later gets used for another

Monophyletic

Includes an ancestor and all of its descendants

Paraphyletic

Includes a common ancestor and SOME but not all of its descendants

Polyphyletic

Includes descendants but no common ancestor