Vocabulary & Definitions
When one species splits into two different species
What is speciation?
A structure that is similar between animals due to their shared ancestry.
What is a homologous structure?
When new organisms come into or out of a population.
What is gene flow?
Domesticated dogs have a dewclaw that no longer serves them any purpose
What is a vestigial structure?
This is the approximate age of Earth
What is 4.6 billion years?
Organisms better adapted to their environment survive and reproduce.
What is natural selection?
Structures that are reduced forms of functional structures in other organisms
What are vestigial structures?
The change in a gene pool due to a shrinking population and less allele variation
What is genetic drift?
Bears in colder climates have thicker fur for survival compared to those in warmer climates
What is an adaptation?
A method that compares fossils based on their position in rock layers
What is relative dating?
Changes in an organism's DNA
What are mutations?
Two structures that look similar but do not come from a common ancestor
What is an analogous structure?
A white horse joins a mostly brown horse population, adding new genes
What is gene flow?
Species that are closer together on a phylogenetic tree share a more recent version of this than species that are farther apart on the tree.
What is a common ancestor?
Scientists use the half-life of carbon to determine the specific age of once-living material
What is absolute dating?
A trait caused by genes that cannot change over an organism’s lifetime.
What is an adaptation?
The wings of bats, flippers of whales, and arms of humans all share the same bone structure.
What are homologous structures?
A group of birds is blown away to a new island and establishes a new population
What is genetic drift?
Scientists will use this sequence to figure out which organisms are closely related to each other
What is a DNA or nucleotide sequence?
This type of non-living material can be dated using both relative dating and absolute dating
What are fossils or rock layers?
A diagram showing evolutionary relationships between organisms.
What is a phylogenetic tree or cladogram?
Animals that face the same environmental pressures evolve to result in this type of structure
What is an analogous structure?
White mice are easier for predators to see against the dark desert ground, so they are eaten more often than tan mice.
What is natural selection?
What scientists look for when comparing DNA sequences and finding differences
What are mutations or differences in nucleotides?
This explains how eukaryotic cells developed by engulfing mitochondria and chloroplasts, forming a symbiotic relationship.
What is the endosymbiotic theory?