Biology 101 (Karoly)

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Dichotomous key

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a key used to determine the identity of things in the natural world

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Homology

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similarity of characteristics of organisms due to shared ancestry

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Homoplasy

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similarity of characteristics of organisms that have developed separately
convergent evolution but independent ancestry

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Phylogeny

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the history of organisms as they change through time
the "tree of life"

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Clade

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a group consisting of an organism and all of its descendants

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Monophyletic

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a taxon that forms a clade
a group consisting of the ancestor and all of its descendants

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Polyphyletic

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a taxon of organisms whose last common ancestor does not share similar characteristics or those that define the taxon

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Paraphyletic

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a taxon that contains the MRCA but only some of the descendants

the taxa Reptilia is an example (birds do not fall into this category but are descended from the same organism as all reptiles)

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Node

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the place on a plant stem where a leaf is attached ???

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Terminal taxa

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???

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Apomorphy

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A trait which characterises an ancestral species and its descendants
An evolutionary novelty for the group under consideration

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Plesiomorphy

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An evolutionary trait that is homologous within a particular group of organisms but is not unique to members of that group
ex: vertebrae are found in zebras, cheetahs, and orangutans, but the common ancestor in which this trait first evolved is so distant that the trait is shared by many other animals. Therefore, possession of vertebrae sheds no light on the phylogenetic relations of these three species.

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Polarity

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???

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Synapomorphy

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a synapomorphy is a derived character state shared by two or more terminal groups and inherited from their most recent common ancestor
ex: Halteres, the uniquely modified hind wings, in all families of winged Diptera. No other group of insects possesses similar structures. However, that all winged Diptera would have the trait and no other group would, is not essential to its being a synapomorphy. It only means that it is easier to determine it is one.

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Autapomorphy

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An apomorphy that is restricted to a single species
It alone cannot provide any information about the phylogenetic relations of that species, although it can indicate the degree of divergence of a species from its nearest relatives.

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Symplesiomorphy

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a trait which is shared between two or more taxa, but which is also shared with other taxa which have an earlier last common ancestor with the taxa under consideration
ex: Five toes on the hind legs in rats and apes. This character-state originated very early in Tetrapoda, occurs in other tetrapod groups, e.g. in lizards, and is thus no indication that the group formed of rats and apes is a clade to the exclusion of these other groups.

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Mosaic evolution

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the concept that major evolutionary changes tend to take place in stages, not all at once

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Outgroup comparison

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looking at a closely related species which is known to be phylogenetically outside the group of species we are studying. The character state in that outgroup is likely to have been ancestral in the group under consideration.
works on the assumption that evolution is parsimonious

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Parsimony

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a rule used to choose among possible cladograms, which states that the cladogram implying the least number of changes in character states is the best

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Cladistics

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a form of biological systematics which classifies living organisms on the basis of shared ancestry. It can be distinguished from other taxonomic systems, such as phenetics, by its focus on evolutionary relationships

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Phenetics

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numerical taxonomy
an attempt to classify organisms based on overall similarity, usually in morphology or other observable traits, regardless of their phylogeny or evolutionary relation (unlike cladistics)

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Morphological (Phenetic) species concept

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Organisms are classified in the same species if they appear identical by morphological (anatomical) criteria ??? direct quote

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Biological species concept

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"species are groups of interbreeding natural populations that are reproductively isolated from other such groups"

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Gene flow

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the transfer of alleles of genes from one population to another (reliant upon migration)

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Genetic drift

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the change in the relative frequency with which a gene variant (allele) occurs in a population due to random sampling and chance
In contrast to natural selection, which makes gene variants more common or less common depending on their reproductive success,[2] the changes due to genetic drift are not driven by environmental or adaptive pressures, and may be beneficial, neutral, or detrimental to reproductive success

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Nonrandom mating

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???

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Gamete pool

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???

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Speciation

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the process of species formation

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Allopatric speciation mode

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the evolution of reproductive isolating mechanisms between two populations that are geographically separated

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Parapatric speciation mode

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speciation between populations with adjacent geographical distributions

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Sympatric speciation mode

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speciation that occurs without the geographic isolation of populations

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Hybridization

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???

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Polyploidy

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the condition of having one or more extra copies of the entire haploid complement of chromosomes

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Autopolyploidy

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the genetic condition of having more than two sets of chromosomes from the same parent species

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Allopolyploidy

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the genetic condition of having two or more complete sets of chromosomes from different parent species

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Reproductive isolating mechanisms

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a biological characteristic that prevents the gene pools or two species from mixing

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Prezygotic isolating mechanism

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a reproductive isolating mechanism that acts prior to the production of a zygote, or fertilized egg
ex:???

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Postzygotic isolating mechanism

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a reproductive isolating mechanism that acts after zygote formation
ex:???

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Meiosis

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the division of diploid cells to haploid progeny, consisting of two sequential rounds of nuclear and cellular division

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Mitosis

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nuclear division that produces daughter nuclei that are exact genetic copies of the parental nucleus

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Haploid

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an organism or cell with only one copy of each type of chromosome in its nuclei
ex:???

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Diploid

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an organism or cell with two copies of each type of chromosome in its nucleus

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Haplobiontic

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???

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Diplobiontic

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???

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Haplontic

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???

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Diplontic

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???

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Zygotic meiosis

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???

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Alternation of generations

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the regular alternation of mode of reproduction in the life cycle of an organism, such as the alternation between diploid (sporophyte) and haploid (gametophyte) phases in plants

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Sporophyte

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an individual of the diploid generation produced through fertilization in organisms that undergo alternation of generations

it produces haploid spores

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Gametophyte

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an individual of the haploid generation produced when a spore germinates and grows directly by mitotic divisions in organisms that undergo alternation of generations

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Spore

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a haploid reproductive structure, usually a single cell, that can develop into a new individual without fusing with another cell

found in plants, fungi, and certain protists

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Megaspore

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a plant spore that develops into a female gametophyte

usually larger than a microspore

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Microspore

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a plant spore from which a male gametophyte develops

usually smaller than a megaspore

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Megagametophyte

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???

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Microgametophyte

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???

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Intragametophytic selfing

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???

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Intergametophytic selfing

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???

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Gamete

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a haploid cell, and egg or sperm. Haploid cells fuse during sexual reproduction to form a diploid zygote

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Zygote

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a fertilized egg

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Embryo

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an organism in its early stage of reproductive development, beginning in the first moments after fertilization

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Sporophyll

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a specialized leaf that bears sporangia

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Sporangia

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(plural) a single-celled or multicellular structure in fungi and plants in which spores are produced

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Archegonia

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(plural) the flask-shaped structure in which bryophyte eggs form

note: bryophyte = a general term for plants that lack internal transport vessels (like mosses)

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Antheridia

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(plural) in plants, a structure in which sperm are produced