Chapter 10 - How we are related Flashcards
Fossil record
The information derived from fossils. The fossil record is arranged in chronological order and helps us map the history of life on Earth, placing species in the appropriate geologic time frame.
Cambrian explosion
a period (–535 mya) of rapid diversification of multicellular life, characterised by evolution of hardened body parts such as shells or bones.
Fossil
The preserved body, impressions, or traces of a dead organism
Fossilisation
The Process by which an organism becomes a fossil
Sediment
Naturally occurring solid material, such as earth and rock, that is broken down into very fine pieces and typically settles at the bottom of liquid.
Sedimentary rock
Rock that has formed through the accumulation of sediment that hardens under pressure
Permineralised fossil
Fossil formed when mineral-rich groundwater deposits minerals like silica and calcite into organic material, creating a mineral relic.
Mould Fossil
Fossil formed when a living thing decomposes underneath sediment, crating a cavity in the shape of the dead organism.
Cast Fossil
Fossil formed when a mould fossil is filled with sediment.
Trace fossil
Fossil or structure indicating the presence of organisms, rather than the organisms themselves (e.g. nests, footprints, and burrows)
Relative dating
a dating technique used to determine the relative age of a fossil by comparing its position to other fossils or rock in surrounding rock strata (layers).
Absolute dating
a dating technique used to determine the absolute age of a fossil by measuring the relative amounts of radioisotopes to their products. Also known as radiometric dating
Fossil Succession
The principle that fossils of the same age will be in the same layer of sedimentary rock, and fossils found in a higher or lower sedimentary layer will be younger or older, respectively. Also known as faunal succession.
Relative age
The age of a fossil as determined by relative dating techniques. Describes the age of a fossil compared to other fossils, instead of a fossils’s exact age in years.
Stratum (pl. strata)
a layer of sedimentary rock
index fossil
a group of widespread fossils which existed for a short period and have a known age. Can be used as a reference to easily determine the age of unknown fossils.
Transitional fossil
a fossil that shows traits that are common to both its ancestral group and its descendant group. They are particularly important when the descendant species is physically very distinct from the ancestral species, such that the transitional fossil can help demonstrate evolutionary changes between the two.
absolute age
an estimate of the age (in years) of a fossil or rock
radioactive isotope
a radioactive atom of a specific element. This atom breaks down into a predictable and stable product. Also known as a radioisotope.
half-life
the time taken for half the mass of a radioisotope sample to break down into its products.
dating period
the range of time since fossilisation in which a particular radioisotope series can be used. Beyond this period, most of the radioisotope will have broken down into its products, meaning that it is too difficult to estimate the fossil’s age.
radiocarbon dating
a form of absolute dating used to determine the age of a fossil by measuring the properties of radiocarbon, a radioactive isotope of carbon. Also known as carbon dating and radioactive carbon dating.
structural morphology
the study of physical structures to establish relatedness
homologous structures
features present in two or more species that may look and function very differently in each species, but are derived from a common ancestor
divergent evolution
the process in which a common ancestor evolves into two or more descendant species
analogous structures
features present in two or more species that fulfil the same function but do not originate from a common ancestor
convergent evolution
the process in which distantly related species evolve similar traits over time due to the action of similar selection pressures.
vestigial structures
features that have lost all or most of their usefulness as a result of evolution by natural selection.
molecular homology
the study of the similarities in the nucleotide sequences of DNA or amino acid sequences in proteins between organisms to establish relatedness
Conserved genes
genes that have remained largely unchanged throughout evolution, and are found across the genome’s of many different species
haemoglobin (Hb)
a protein found in red blood cells that is responsible for the transport of oxygen in the body.
cytochrome c
an enzyme found in mitochondria that carries electrons in aerobic and anaerobic respiration reactions
mitochondrial DNA (mtDNA)
circular DNA found in mitochondria
DNA (deoxyribonucleic acid)
a double-stranded nucleic acid change made up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism survival
Nucleotide
the monomer subunit of nucleic acids. Made up of a nitrogen-containing base, a five-carbon sugar molecule (ribose in RNA and deoxyribose in DNA), and a phosphate group.
genome
the complete set of DNA housed within an organism
Nuclear DNA
DNA that is located in the nucleus of a cell
Phylogenetics
the study of relatedness between organisms
phylogenetic tree
a diagram used to show the relatedness between organisms
evolutionary relationship
the relatedness of organisms based on shared ancestry
lineage
a direct sequence of species that evolved from a common ancestor
taxon (pl. taxa)
a unit of biological classification into which related organisms are classified. Taxa are arranged in a hierarchical rank from kingdom down to species, where members of a specific taxon typically share certain morphological characteristics.
root
represents the most recent common ancestor for all members of a phylogenetic tree
branch
a line on a phylogenetic tree that represents an evolutionary path
node
the splitting point between two branches on a phylogenetic tree, representing a speciation event
leaf
the end of a branch that shows the current (or final) form of a species
adaptive radiation
the rapid divergent evolution of a species, thereby producing a wide array of species/forms
Punctuated equilibrium
A theory in evolutionary biology that proposes that after a period of rapid evolution following a speciation event, a species becomes stable for a long period of time.
Polyhyly
A grouping of similiar organisms that do not share a common ancestor (with those similarities)
Homoplasy
An analogous structure; a feature found in two unrelated species, having evolved independently in each due to similiar selection pressures.
