Part 2 Flashcards
Phylogeny
History of evolutionary relationships among organisms or their genes
Parallel evolution
Existence of highly conserved developmental genes makes it likely that similar traits will evolve repeatedly, especially among closely related species
Phylogenetic tree
Diagram that portrays a reconstruction of history of evolutionary relationships among organisms or their genes
Node
Branching point in a phylogenetic tree; ie when species lineages divide into 3 by speciation
Root
Common ancestor of all the organisms in the tree
Taxon (plural taxa)
Any species or group of species that we designate or name; ie humans
Clade
Any taxon that consists of an ancestor and all of its evolutionary descendants
Sister species
2 species that are each other’s closest relatives
Sister clades
Any 2 clades that are each other’s closest relatives
Systematics
Study and classification of biodiversity
Tree of life
Complete evolutionary history of life
Homologous
Any features shared by 2 or more species that have been inherited from a common ancestor
Ancestral trait
Trait that was present in the ancestor of a group is known
Derived trait
Trait found in a descendant that differs from its ancestral form
Synapomorphies
Derived traits that are shared among a group of organisms and are viewed as evidence of the common ancestry of that group
Convergent evolution
Phenomenon where independently evolved traits subjected to similar selection pressures may become superficially similar
Evolutionary reversal
Character may revert from a derived state back to an ancestral state
Ingroup
Group of organisms of primary interest in phylogenetic analysis
Outgroup
Compared with the ingroup; species or group that is closely related to the ingroup but is known to be phylogenetically outside it; root of the tree is located between the ingroup and the outgroup
Parsimony
Preferred explanation of our observations is the simplest explanation
Morphology
Presence, size, shape, and other attributes of body parts; important source of phylogenetic information
Maximum likelihood
Methods that identify the tree that is most likely to have produced the observed data, given the assumptions of the model
Molecular clock
Average rate at which a given gene or protein accumulates changes, and this rate of change can be used to gauge the time of a particular split in phylogeny
Genus (plural genera)
Group of closely related species; ie Homo in Homo sapiens
Family
Taxon above the genus in the Linnaean system; suffix “-idae”
Monophyletic
Expectation that taxon contains an ancestor and all descendants of that ancestor, and no other organisms
Geological time scale
Evolutionary changes, such as the appearance of new species and evolutionary lineages
Strata (singular stratum)
Oldest layers of rock lying at the bottom
Stratigraphy
Steno observations of fossils in sedimentary rocks; 3 principles
Radioisotopes
Radioactive isotopes of elements that decay in a predictable pattern over long periods
Half-life
Specific time it takes for half of the atoms in a radioisotope decay to become a different, stable (nonradioactive) isotope
Radiometric dating
Using half-life and radioisotopes to date fossils and rocks
Igneous rocks
Formed when molten material cools
Eons
4 in broad history of life; Hadean, Archean, Proterozoic (Precambrian) + Phanerozoic
Continental drift
Alfred Wegener theory that Earth’s land masses changed their positions over the millennia
Plate tectonics
Geophysics of the movement of land masses
Lithosphere
Stone Sphere; Earth’s crust of several solid continental and thinner oceanic plates
Asthenosphere
Weak Sphere; malleable layer of Earth’s mantle
Subduction
Where oceanic plates and continental plates converge, the thinner oceanic plates is forced underneath the thicker continental plate
Biota
Assemblage of all organisms of all kinds living at a particular time or place
Flora
All of the plants living at a particular time or place
Fauna
All of the animals living at a particular time or another place
Plankton
Small floating oraganisms
Cambrian explosion
Rapid diversification of life that continued for 60 million years
Laurasia
Large continent of Pangea that drifted northward during the Jurassic period
Gondwana
Large continent of Pangea that drifted southward during the Jurassic period
Epochs
Subdivisions of the Cenozoic era periods (Tertiary and Quaternary)
Species
Group of organisms that can mate with one another and produce fertile offspring
Speciation
Divergence of biological lineages and the emergence of reproductive isolation between those lineages
Species concepts
Different ways of approaching the question “what are species?”
Morphological species concept
Species comprises individuals that “look alike”; by Carolus Linnaeus
Reproductive isolation
State in which two groups of organisms can no longer exchange genes
Biological species concept
By Ernst Mayr; “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other groups”
Lineage species concept
One species splits into two descendant species, which thereafter evolve as distinct lineages; by evolutionary biologists
Lineage
Ancestor-descendant series of populations followed over time
Allopatric speciation
Speciation that results when a population is divided by a physical barrier
Sister species
Species that are each other’s closest relatives may exist on either side of the geographic barrier
Sympatric speciation
Speciation without a physical barrier or isolation
Polyploidy
Most common means of sympatric speciation; results from the duplication of sets of chromosomes within individuals
Autopolyploidy
Polyploidy that arises from chromosome duplication in a single species
Allopolyploidy
Polyploidy from the combining of the chromosomes of two different species
Reinforcement
Strengthening of mechanisms that prevent hybridization
Prezygotic isolating mechanisms
Mechanisms that prevent hybridization from occurring
Postzygotic isolating mechanisms
Mechanisms that reduce that fitness of hybrid offspring
Evolutionary radiation
Rapid proliferation of a large number of descendant species from a single ancestor species
Adaptive radiation
Rapid proliferation of species results in an array of species that live in a variety of environments and differ in characteristics they use to exploit those environments
Polygynous
Mating system in which a male has more than 1 mate
Polyandrous
Mating system in which a female has more than 1 mate
Altruistic (?)
Behavior is favored because increases fitness of performer but benefits another individual at a cost to the performer (?)
Direct fitness
Fitness gained by producing offspring
Inclusive fitness
Individuals direct fitness plus its indirect fitness
Indirect fitness
Reproductive success of the individual’s relatives, to the extent that those relatives share the individual’s alleles
Kin selection
Selection for behaviors that increase the reproductive success of relatives even when they come at a cost to the game performer; driven by maximization of inclusive fitness
Hamilton’s rule
W.D. Hamilton’s formalized concept of kin selection; argues that for an apparent altruistic behavior to be adaptive, the fitness benefit of that act to the recipient times the degree of relatedness between the performer and the recipient has to be greater than the cost to the performer
Eusociality
Hamilton’s rule applied here; social groups that include nonreproductive individual members; ie- sterile females in bee colonies (Hymenoptera insect group)
Haplo-diploidy
Sex determination mechanism of hymenopterans in which diploid individuals are female and haploid individuals are male
