Macroevolution: Speciation and Evolutionary History

microevolution

Change in allele frequencies in a population over generations.

macroevolut

major evolutionary change. The term applies mainly to the evolution of whole taxonomic groups over long periods of time.

Speciation

Formation of new species

biological species

Species is a group of populations whose members have the potential to produce fertile offspring. (main concept)

Morphology species

Classification based on observable and measurable phenotypic traits

(Used with asexual organisms and fossils)

phylogenetic species concept

A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.

reproductive isolation

Separation of species or populations so that they cannot interbreed and produce fertile offspring, final stage of speciation

prezygotic barriers

Barriers that impede mating or hinder fertilization.

postzygotic barriers

Barriers that prevent the hybrid zygote from becoming a fertile adult.

Habitat (geographic) isolation

A type of reproductive isolation due to separation by an impassable geographic barrier such as a mountain range, body of water, etc.

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

mechanical isolation

Morphological differences prevent fertilization.

reduced hybrid fertility

hybrids fail to produce functional gametes

reduced hybrid viability

When the genes of different species interact and impair hybrid development.

hybrid breakdown

Some first-generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile

Gradualism (Gradual Evolution)

The theory that evolution occurs slowly but steadily

puncuated equilibrium

evolution happens in spurts rather than being steady

Francesco Redi

This scientist disproved spontaneous generation by showing that maggots do not spontaneously arise from decaying meat.

Louis Pasteur

A French chemist, this man discovered that heat could kill bacteria that otherwise spoiled liquids including milk, wine, and beer.

Stanley Miller's experiments

Simulated conditions of primitive Earth, producing amino acids, sugars, and nucleotide bases

origin of life steps

Generation of organic monomers ('building blocks')

Production of polymers (macromolecules)

Packaging of polymers into protocells

Self-replicating polymers form and persist in protocells

geologic record

a standard time scale that divides Earth's history into four eons and further subdivisions

relative dating

Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock

radiometric dating

4 eons of geologic time

Hadean, Archean, Proterozoic, Phanerozoic

4 eras of geologic time

Precambrian, Paleozoic, Mesozoic, Cenozoic

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

divergent evolution

when two or more species sharing a common ancestor become more different over time

Coevolution

Process by which two species evolve in response to changes in each other

plate tectonics

A theory stating that the earth's surface is broken into plates that move.

Pangaea

The name of the single landmass that broke apart 200 million years ago and gave rise to today's continents (geographic isolation)

Extinction

A term that typically describes a species that no longer has any known living individuals.

background extinction

extinction caused by slow and steady process of natural selection (rates become higher due to humans)

mass extinction

event in which many types of living things become extinct at the same time (5 mass extinctions but currently in 6th)

Taxonomy

The scientific study of how living things are classified

common names

nicknames of sorts learned by familiarity (confusing)

binomial nomenclature

Classification system in which each species is assigned a two-part scientific name (genus and species)

Carolus Linnaeus (1707-1778)

specialized in taxonomy, developed a binomial system of naming organisms according to genus and species that is still used today. Also adopted a system for grouping similar species into a hierarchy of increasingly general categories. (classified only plants and animals by physical characteristics)

Genus

A classification grouping that consists of a number of similar, closely related species

Species

A group of similar organisms that can breed and produce fertile offspring.

3 domains of life

Bacteria, Archaea, Eukarya

Bacteria

single-celled organisms that lack a nucleus; prokaryotes

Archaea

Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan (extremophiles)

Eukarya

Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals

7 taxas

Kingdom, Phylum, Class, Order, Family, Genus, Species

Phylogeny

Evolutionary history of a species

Cladistics

An approach to systematics in which organisms are placed into groups called clades based primarily on common descent.

shared ancestral characteristics

A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.

shared derived traits

the unique features shared by all members of a group that originated in the group's most recent common ancestor