DC 1407 Spring Final

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Affect of natural selection

Changes in phenotypic allele frequency in a population

Gene flow

movement of alleles from one population to another population that does not migrate

Mutation

change in a DNA sequence that affects genetic information, ultimate source of genetic variation

genetic drift

random change in allele frequencies that occurs in small populations

Fitness

The reproductive success (number of descendants) of an individual organism relative to the average reproductive success of the population.

bottleneck effect

a reduction in the genetic diversity of a population caused by a reduction in its size

founder effect

change in allele frequencies as a result of the migration of a small subgroup of a population

vestigial structures

A structure that is present in an organism but no longer serves its original purpose

homologous structures

similar structures that related species have inherited from a common ancestor

analogous structures

similarities among unrelated species that result from convergent evolution

Hardy-Weinberg equilibrium

condition that occurs when the frequency of alleles in a particular gene pool remain constant over time

Hardy-Weinberg equation

p2 + 2pq + q2 = 1

directional selection

occurs when natural selection favors one of the extreme variations of a trait

stabilizing selection

Natural selection that favors intermediate variants by acting against extreme phenotypes

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

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

artificial selection

Breeding organisms with specific traits in order to produce offspring with identical traits. Changes can occur rapidly

Archaeopteryx

An intermediate fossil that shows both dinosaur and bird characteristics (feathers)

Biogeography

inhabitants of oceanic islands resemble forms from nearest mainland but some differences due to habitat

molecular clock

Model that uses DNA comparisons to estimate the length of time that two species have been evolving independently

Evidence of Evolution

1) Fossil Record

2) Embryology

3) Homologous Structures

4) DNA

5) Vestigial Structures

Gradualism

The theory that evolution occurs slowly but steadily

punctuated equilibrium

Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

sympatric speciation

The formation of new species in populations that live in the same geographic area

prezygotic isolation

a barrier to successful breeding that occurs before fertilization, such as differences in mating time or behavior

ecological isolation

species occur in the same area, but they occupy different habitats and rarely encounter each other

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

temporal isolation

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

mechanical isolation

Morphological (physical) differences can prevent successful mating

prevention of gamete fusion

gametes of one species function poorly with the gametes of another species or within the reproductive tract of another species

postzygotic isolation

reproductive isolation that occurs after members of two different species have mated and produced a hybrid offspring. Such hybrids are usually unable to reproduce

hybrid sterility

postzygotic barrier; the hybrid is infertile or do not survive to adult

Biological Species Concept (BSC)

Defines species as groups of interbreeding populations that are reproductively isolated

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.

Autopolyploidy

chromosome duplication in a single species to form tetraploid, can self-fertilize or mate with other tetraploids

allopolyploidy

polyploidy resulting from contribution of chromosomes from two different species

Systematics

study of the diversity of life and the evolutionary relationships between organisms

Phylogeny

Evolutionary history (tree) of a species or group of species.

derived characters

Characteristic that appears in recent parts of a lineage, but not in its older members, seen in cladograms between branch points

Clade

A group of species that includes an ancestral species and all its descendants.

Synapomorphies

shared derived characters by a clade

Plesiomorphies

ancestral character states

Symplesiomorphies

shared ancestral states

polyphyletic group

A taxonomic grouping consisting of several species that lack a common ancestor (more work is needed to uncover species that tie them together into a monophyletic clade).

monophyletic group

group that consists of a single ancestral species and all its descendants and excludes any organisms that are not descended from that common ancestor

Homoplasy (convergent evolution)

independent evolution of similar features in species of different lineages

Endosymbiosis

A theorized process in which early eukaryotic cells were formed from simpler prokaryotes. Origin of chloroplasts and mitochondria

principle of parsimony

when competing explanations or theories fit the facts, the simplest is preferred. Create tree based on fewest character states

nucleoid region

The region in a prokaryotic cell consisting of a concentrated mass of DNA.

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

Pili

Appendages that allow bacteria to attach to each other and to transfer DNA

Flagella

A long, whip-like filament that helps in cell motility. Many bacteria are flagellated

Ribosomes

site of protein synthesis

cell membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Transformation

process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria

Transduction in bacteria

DNA is transferred from one bacteria to another by a virus

Conjugation

In bacteria, the direct transfer of DNA between two cells that are temporarily joined.

Tuberculosis

Mycobacterium tuberculosis, respiratory illness

peptic ulcer

open sore in the lining of the stomach or duodenum, caused by bacteria

Dental Caries (Tooth Decay)

-Erosion of tooth surface causing infection.

caused by bacteria

penicillium killing bacteria

competitors

Gram-positive bacteria

Bacteria that have a thick peptidoglycan cell wall, and no outer membrane. They stain very darkly (purple) in Gram stain.

Gram-negative bacteria

type of bacteria that stain red with Gram stain and have a thin cell wall with an outer membrane

Photoautotrophs

Organisms that use light as a source of energy to synthesize organic substances.

Photoheterotrophs

An organism that uses light to generate ATP but that must obtain carbon in organic form.

Chemolithoautotrophs

energy from inorganic compounds

Chemoheterotrophs

acquire energy and carbon from organic molecules

Viral entry

needs surface receptors

lysogenic cycle

a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA

lytic cycle

a viral reproductive cycle in which copies of a virus are made within a host cell, which then bursts open, releasing new viruses

Capsid

protein coat surrounding genetic component of virus

envelope

a membrane like layer that covers the capsids of some viruses

Retrovirus

virus that contains RNA as its genetic information, HIV

Protist

Kingdom composed of eukaryotes that are not classified as plants, animals, or fungi

Irish Potato Famine

caused by oomycotes

Giardia

A microorganism that infects the digestive system from unclean water

Trichmonas vaginalis

STD

Leishmaniasis

caused by Trypanosomes

African sleeping sickness is caused by

Trypanosoma

Toxoplasmosis

Toxoplasma, can cross placenta

Phototropic protist

contains chlorophyll

Excavata

the eukaryotic supergroup that contains flagellated single-celled organisms with a feeding groove

Alveolata

A eukaryotic superkingdom, defined by the presence of cortical alveoli, small flattened vesicles that, in some species, store calcium ions.

Diatoms

unicellular algae that have a unique glass-like wall made of silica

Dinoflagellates

Group of protists that form "blooms", can be toxic. make up phytoplankton and can be bioluminescent. They generally have two flagella, half are heterotrophic and the other half are photosynthetic, many species are luminescent

Ciliates

a type of protozoa that moves using hairlike cilia and have 2 different types of nuclei

Oomycetes

water molds and responsible for potato famine

Amoebozoans

A protist in a clade that includes many species with lobe- or tube-shaped pseudopodia used for movement

endosymbiotic theory

theory that eukaryotic cells formed from a symbiosis among several different prokaryotic organisms. Evidence:

1. genes have close relationship to prokaryotes

2. Some enzymes are unique to them

3. outer membrane is similar to plasma membrane

protist mitosis

nuclear membrane fails to breakdown

Phagotrophic

Feeding by engulfing a food cell or particle and ingesting it. Use lysosomes to breakdown

characteristics of fungi

Eukaryotic, heterotrophs, multicellular, cell wall(chitin), filamentous (hypahae)

Chytridiomycota

Form spores with flagella in water, responsible for amphibian die-off. Allomyces

mycorrhizal fungi

fungi that surround plant roots and help plants obtain water and minerals, an extension of root system

Ectomycorrhizae

mycorrhizae in which the fungal hyphae do not penetrate the root cells of the plant

arbuscular mycorrhizae

hyphae enter root and penetrate cell walls but not the plasma membrane.

mutualistic relationships with fungi

mycorrhizae & leaf cutter ants