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Geological Time. Microevolution is…. Any time you consider… natural selection genetic drift (within species) mutation gene flow between populations, or the randomness of mating within populations Indeed, all things up to and just about including the act of speciation itself
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Microevolution is… • Any time you consider… • natural selection • genetic drift (within species) • mutation • gene flow between populations, or • the randomness of mating within populations Indeed, all things up to and just about including the act of speciation itself • …you are considering microevolutionary processes
Any time you consider… • the likelihood of births of new species (speciation events) • the likelihood of the death of species (extinction) • the adaptive radiation of lineages (birth of many species) • mass extinction (death of many species) • evolutionary relationships between species • the evolutionary history of a lineage • biogeography, or • shared derived characters • …you are considering macroevolutionary processes Macroevolution is…
Note that the adaptation of a species to its natural environment (microevolution) will not necessarily have a positive impact on the ability of that species to give rise to descendant species (macroevolution)… • That is, microevolution and macroevolution are not identical processes • However, microevolutionary processes do impact on macroevolutionary processes • For example, macroevolution is affected by the adaptations displayed by organisms (e.g., dispersal or dormancy ability) and adaptations are a product of selection (a microevolutionary process) Caveats
Paleontology is the study of the biology of the past Paleontology
Monday (today, and perhaps a little of Tuesday) we’ll be finishing up Chapter 25 • Monday (today’s) lab will not be Protists and Fungi but, instead, will be our first Animal Diversity lab (Topic 17) • The reason for starting with animals (apparently) is so that we can view Fungi closer to covering Fungi, Plants closer to covering Plants, and Protists after covering Protists (Oh well…) • Tuesday (tomorrow) will be a recitation • Wednesday will be the exam, with approximately 8, 11, 8, and 8 questions from chapters 22, 23, 24, & 25, respectively • Thursday we will start our Diversity of Life unit with Chapter 26 This Week in Bio 114
Relative vs. Absolute Dating • Relative dating: • Geological time scales • Relative position in strata • Index fossils • Absolute dating: • Actual “clock” • E.g., radioactive decay • Clock must be started Dating Fossils
Relative Dating Illustration of potential complexity of strata
Relative Dating Illustration of Index Fossils and their role in Relative Dating
Classifying Organisms • Fossils allow us to compare extinct organisms with modern organisms • People study fossils to understand past environments plus to discover clues to evolutionary relationships among organisms • Taxa (sing. taxon) are units of classification of organisms • So far we have considered the taxonomic categories species & domain • Ideally, all taxonomic categories group organisms according to evolutionary (blood) relationships
Do (Domain) Keep (Kingdom) Privates (Phylum) Clean (Class) Or (Order) Forget (Family) Getting (Genus) Sex (Species) Taxonomic Categories
Binomial Nomenclature Examples: Escherichia coli, E. coli, Escherichia spp., and “the genus Escherichia” The genus name (Escherichia) is always capitalized The species name (coli) is never capitalized The species name is never used without the genus name (e.g., coli standing alone, by itself, is a mistake!) The genus name may be used without the species name (e.g., Escherichia may stand alone, though when doing so it no longer actually describes a species) When both genus and species names are present, the genus name always comes first (e.g., Escherichia coli, not coli Escherichia)
Binomial Nomenclature Both the genus and species names are always italicized (or underlined)—always underline if writing binomials by hand The first time a binomial is used in a work, it must be spelled out in its entirety (e.g., E. coli standing alone in a manuscript is not acceptable unless you have already written Escherichia coli in the manuscript) The next time a biniomial is used it may be abbreviated (e.g., E. for Escherichia) though this is done typically only when used in combination with the species name (e.g., E. coli) The species name is never abbreviated
Homologies are similarities between organisms that are present due to common descent • Common descent means that the (the organisms) share ancestry / are evolutionarily related • Clades are defined by shared derived characters (a.k.a., Synapomorphies) • Synapomorphies are those homologies that are unique to individual taxa • That is, the common ancestor and all of the descendant species share (in one form or another) a given homology… • And, organisms not found in a given clade do not share the shared derived character • Contrast, shared primitive characters Synapomorphies
These are Analogies For Birds this is Shared Derived For Mammals these are Primitive Primitive & Shared Derived Characters
16S rRNA 16S RNA Trees
