The Fossil Record Flashcards
Evolution can only occur if variation exists. List 3 causes of evolutionary change
- natural selection
- gene flow
- genetic drift
define gene flow
movement of genes between populations.
-introduces genes into a population, increasing genetic variation
define Genetic drift
- random changes in the gene frequency in a population
- new population can become genetically distinct from original population
Taxonomy of Human
Kingdom- Animalia Phylum- Chordata Class- Mammalia Order- Primates Family- Hominidae Genus- Homo Species- sapiens
what is the Founder Effect
New populations that became isolated from the parent population carry only the genetic variation of the founders
define Homology
Similarity of trait resulting from shared ancestry
define Analogy
Similarity of traits resulting from similar use, not due to shared ancestry
define Homoplasy
process that leads to the development of analogies
define Ancestral traits
traits inherited from ancestors
dfine derived traits
traits that are evolved from the ancestral condition
define phylogeny
family tree
Biological species concept
- a group of organisms that have the ability to interbreed and produce viable offspring
- are reproductively isolated from all other such groups
define clade
cluster of species linked by a set of unique traits
define Speciation
the process by which a new species evolves from an earlier species
define Anagenesis
- one species evolves into another over time.
- first species no longer exists
define cladogenesis
- a species branches into two or more new species
- first species may or may not still exist
Punctuated Equilibrium
involves long periods of stasis punctuated by bursts of change
define Gradulaism (gradual evolution)
involves small, steady changes over vast amounts of time
The fossil record
the remains of once-living things, wholly or partially transformed into rock through chemical replacement
The more fossils we have, the better our understanding. List 3 reasons why the record is incomplete;
- palaeontologists have searched in some places but not all
- fossils have been preserved in some places but not others
- rock sequences containing fossils are not complete in all places
Mammals are vertebrates. Define vertebrate
- have spine with sheath of nerves leading to brain and skull
- have four limbs with pentadactyl ends (e.g. fingers and toes)
Early mammals evolved from?
cynodonts
define Adaptive radiation
massive increase in species from a single stem group
