Midterm 1 Flashcards
Laggerstatten
A site with abundant supply of unusually well-preserved fossils from the same period of time, often including soft tissues
Burgess Shale
A laggerstatten in Canada that preserved fossils from the Cambrian period like that weird spiky animal
Biomarker
Molecular evidence of life in the fossil evidence. This can include chemicals like Okenone that can only be created by living organisms
Stromatolites
Layered structures formed by the mineralization of bacteria (Large rock like mounds)
Ediacaran fauna
A group of animal species that existed between 575 and 535 mya (before the Cambrian period)
Chordates
Members of a diverse phylum that includes vertebrates, lancelets, and tunicates. They all have a notochord which is a hollow nerve chord, gill slits, and a post anal tail as embryos
Trilobites
Now extinct marine arthropods that diversified during the Cambrian period and gradually died out during the Devonian
Prokaryotes
Organisms lacking a nucleus, or any other membrane bound organelles. They include Archaea as well
Tetrapods
Vertebrates with four limbs. Living tetrapods include mammals, birds, reptiles and amphibians
Teleosts
A lineage of bony fish that comprise most living species of vertebrates. They include goldfish, salmon, and tuna. They can be distinguished from other fishes by unique traits like the mobility of an upper jawbone
Synapsids
A lineage of tetrapods that emerged 300 million years ago and gave rise to mammals
Hominin
Humans and all species more closely related to humans than to Chimpanzees
Phylogeny
A visual representation of the evolutionary history of populations, genes, or species
Tips of a phylogeny/tree
The terminal ends of an evolutionary tree representing species, molecules, or populations being compared
Branches
Lineages evolving through time between successive speciation events
Node
A point in a phylogeny where a lineage splits (speciation!)
Internal nodes
Nodes within a phylogeny representing ancestral populations or species
Clade
An organism and all of its descendants
Monophyletic
A term used to describe a group of organisms that form a clade
Characters
Heritable aspects of organisms that can be compared across taxa
Taxon (Taxa)
A group of organisms that a taxonomist judges to be a taxonomic unit like a species or an order. (Depends on what the tree is depicting
Synapomorphy
A shared derived character that comes from a common ancestor and was inherited by all its descendants
Cladistics
Phylogenetic methods that construct trees by grouping taxa into clades according to their shared derived characters
Homplasy
Character state similarity not due to shared descent but maybe by convergent evolution or evolutionary reversal
Convergent evolution
The independent origin of similar traits in separate lineages
Evolutionary reversal
The reversion of a derived character state to its ancestral state
Exaptation
A trait that originates performing one function, and which is later co-opted for a new function. Ex) How the synapsid jaw eventually became todays ear bones
Background extinction
The normal rate of extinction for a taxon or biota
Mass extinction
A statistically significant departure from background extinction rates that results in substantial loss of taxonomic diversity
What were the big five mass extinctions?
The Ordovician event, the Devonian event, the Permian event, the Triassic event, and the Cretaceous event
Coevolution
Reciprocal evolutionary change between interacting species, driven by natural selection
Reciprocal selection
Selection that occurs in two species, due to their interactions with one another. Reciprocal selection is the critical prerequisite of coevolution.
Geographic mosaic theory of coevolution
A theory that proposes that the geographic structure of populations is central to the dynamics of coevolution. The direction and intensity of coevolution varies from population to population, and coevolved genes from these populations mix together as a result of gene flow
Coevolutionary escalation
Species interact antagonistically in a way that results in each species exerting reciprocal directional selection on the other. As one species evolves to overcome the other, it in turn selects for new weaponry in its opponent.
Mullerian mimicry
Occurs when several harmful or distasteful species resemble each other in appearance, facilitating the learned avoidance of predators
Batesian Mimicry
Occurs when harmless species resemble harmful or distasteful species, deriving protection from predators in the process
Endosymbionts
Mutualistic organisms that live within the body or cells of another organism
Retrovirus
An RNA virus that used an enzyme called reverse transcriptase to become part of the host cells’ DNA. HIV is an example
