Bio 1108 (UConn)

Ecology and Evolutionary Biology

Genetic Variation

Differences in DNA sequences

Species

Group of individuals that can exchange genetic material through interbreeding or share allele through reproduction

Gene pool

All the alleles present in all individuals in a species

Population

Interbreeding group of organisms of the same species living in the same geographic area

Variable

Around the mean value

Locus

Specific physical location of a gene or marker on a chromosome

Loci

Plural of locus

Alleles

An alternative version of a specific gene found in the same place on a chromosome

Genotype

An individual’s unique set of genetic instruction or DNA sequence

Phenotype

The physical traits that are a result of a genotype

pheno-

show, seem, appear

geno-

offspring, gene

-type

a form

homo-

same

hetero-

different

-zygous

a yoke, a pair

allele frequency =

number of copies of an allele / total number of alleles in a population

Scientific Method

Observation, Gather knowledge, Hypothesis, Test hypothesis, Conclusion, Publication

Meniscus

The low curve used when measuring a liquid

Genetic Drift

The statistical problem of small populations (random event)

Migration

Gene flow

Nonrandom mating

mate choosing, domestication, inbreeding, etc.

Molecular clock

Technique used to determine when two or more species diverged from a common ancestor

The great equalizer

energy trade off

Somatic Mutions

Occur in the body tissues, not passed on

Germ-line mutations

Occur in reproductive tissues, are passed on the offspring

Neutral mutations

Have no effect

Deleterious mutations

Have a harmful effect on individual and potentially offspring (natural selection)

Advantageous mutations

Mutations that aid in survival, beneficial

Fixation

When one allele replaces all other alleles

Hardy-Weinberg Equilibrium

no differential survival or repetitive success, no migration, no mutation, no small population, no mate choice

Positive selection

Process that favors advantageous traits

Balancing selection

Maintains two or more alleles

Stabilizing selection

Goes against both extremes

Directional selection

Shift in mean value of a trait over time

Artificial selection

Used in agriculture, efficient because of lack of competition

Intrasexual

Species of the same gender go against each other for a mate

Intersexual

One gender in a species attempts to impress the other gender in order to mate

Inbreeding depression

A reduction in fitness caused by homozygosity

Negative selection

Eliminates non favorable traits, effective in eliminating amino changing histone mutations

Pseudogene

A gene that is no longer functional

Sexual selection

Evolution of traits that increase an individuals access to members of the opposite sex

Molecular evolution

Change in DNA or amino acid sequences over time

Speciation

The process by which one species becomes 2

Biological species concept

Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups

Morphospecies concept

Members of the same species usually look similar

Polymorphisms

When members of the same species don’t look alike (Male vs. Females, Caterpillar vs. Butterfly)

Cryptic species

organisms that used to be considered one species but turned out to be different using DNA

Hybridization

First pair are two species while the second pair is just one

Ecological niche

A complete description of the role a species plays in their environment

Phylogenetic species

Members of a species all share a common ancestor

Prezygotic isolation

Factors that prevent reproduction before fertilization

Postzygotic isolation

Factors that prevent reproduction after fertilization

Geographic isolation

A form of prezygotic isolation, individuals are separated in space

Ecological isolation

Separated based on where they live or what they do in an environment

Temporal isolation

Individuals are reproductively active at different times

Behavioral isolation

Individuals only mate based on specific courtship rituals, songs, behaviors

Mechanical isolation

Individuals are unable to mate due to structural incompatibility

Partially reproductively isolated

Two diverged populations who are genetically different enough for hybrid offspring to have reduced fertility

Allopatric speciation

New species forms because a population has a physical barrier separating them

Dispersal

Some individuals colonize a distant place from their parents

Vicariance

Geographic barrier raises in one population

Peripatric speciation

Few individuals disperse into a new location and evolve separately

Island populations

An isolated population

Sympatric populations

An isolated population that occurs without barriers

Wallace effect

There should be selection against hybridization

Allo-

other, different

-patric

united, one, family

Co-speciation

When organisms speciate in response to each other. One changes a bit and the other one changes in response to the first.

Forks (Nodes)

Represent the most common ancestor of two descendent groups

Taxa

A named taxonomic group at any rank, such as a species, a gems, or a family

Monophyletic

All members share a single common ancestor, also called a clade

Paraphyletic

Contains some but not all of the descendants of a common ancestor

Polyphyletic

Does not include the last common ancestor

Genus

Closely related species

Family

A group of closely related genera

Order

Rank of classification consisting of one or more closely related families

Domains

Three largest groups in the tree of life (Eukarya, Bacteria, Archaea)

Characters

Morphological, physiological, or molecular features that make up an organism

Character states

Observed condition of a character

Homology

Characters found similar in different species because of a shared ancestor

Analogy

Similar characters in different species that are a result of same environmental pressures, not a common ancestor

Synapomorphies

A shared derived character

Cladistics

Phylogenetic reconstruction on the basis of shared evolutionary changes in characters

Outgroup

Group of organisms that has a common ancestor than the common ancestor of interest, used as a reference

Parsimony

Choosing the simplest hypothesis to account for a given set of observations

Trace fossils

Track or trail left by an animal during movement/burrowing

Molecular fossils

Sterol, bacterial lipid, or pigment that is resistant to decomposition left in a fossil

Geologic timescale

A series of time divisions that mark Earth’s long history

Radiometric dating

Using the decay of radioisotopes as a yardstick

Half-life

The time it takes for an amount of substance to reach half of its original value

Mass extinction

Catastrophic drop in recorded diversity

Cambrian explosion

Phase of rapid diversification 541 million years ago

Multiregional Hypothesis

The idea that modern humans derive from the Homo ergaster populations that spread around the world starting 2 million years go

Out-of-Africa Hypothesis

The idea that modern humans arose from homo heidelbergensis descendants in Africa before dispersing beyond Africa around 60,000 years ago

Mitochondrial DNA

A small circle of DNA, about 17,000 base pairs long in humans, found in every mitochondrion

Neotny

The process in which the timing of development is altered so that a sexually mature organism retains the physical characteristics of the juvenile form

Endomembrane system

Network of membranes in eukaryotes

Endocytosis

Eukaryotic cells that engulf molecules or particles

Phagocytosis

A form of endocytosis, where food particles are packaged and bud off from the cell membrane