BSC 2011C Terminology Review

DNA

Deoxyribonucleic acid; the genetic material containing instructions for the development and function of all known living organisms.

Convergent evolution

The independent evolution of similar features in different lineages. macroevolution

Extinct

No longer in existence; having died out.

Allele

A variant form of a gene.

Biogeography

The study of the geographic distribution of species.

Extant

Still in existence; surviving.

Paleontology

The study of prehistoric life, including fossils.

Trait

A distinct variant of a phenotypic character of an organism.

Evolutionary Tree

A branching diagram showing the evolutionary relationships among various biological species.

Genotype

The genetic makeup of an organism.

Phenotype

The observable characteristics of an organism resulting from the interaction of its genotype with the environment.

Genome

The complete set of genes or genetic material present in a cell or organism.

Natural selection

The process by which organisms better adapted to their environment tend to survive and reproduce more successfully.

Adaptation

An inherited trait that enhances survival and reproduction of an organism in a particular environment.

Endemic species

A species that is unique to a defined geographic location.

Fossil

The preserved remains or traces of an organism from a past geological age.

Artificial selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

Geologic strata

Layers of rock that provide a chronological record of Earth's history.

Homologous structure

Structures in DIFFERENT species that are similar BECAUSE of common ancestry.

Analogous structure

Structures in DIFFERENT species that are similar in function but NOT due to common ancestry; they evolved independently.

Population

A group of individuals of the same species living in the same area and interbreeding.

Differential reproduction success

The variation in the reproductive output among individuals in a population.

Descent with modification

The concept that species change over time, giving rise to new species, and share a common ancestor.

Homozygous

Having two identical alleles for a given gene.

Heterozygous

Having two different alleles for a given gene.

Gene

A unit of heredity that is transferred from a parent to offspring and determines some characteristic of the offspring.

Emigration (genes)

The movement of genes out of a population.

Gene flow

The transfer of genetic material from one population to another.

Immigration (genes)

The movement of genes into a population.

Mutation

A change in the nucleotide sequence of an organism's DNA.

Gene pool

The aggregate of all copies of every type of allele at all loci in every individual in a population.

DNA nucleotides

The building blocks of DNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Recombination

The rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA.

Independent assortment

The random orientation of homologous chromosomes during meiosis.

Macroevolution

Evolutionary change ABOVE the species level.

Microevolution

Evolutionary change WITHIN a species or small group of organisms, especially over a SHORT period.

Genetic Drift

A change in the allele frequency of a population as a result of chance events rather than natural selection.

Genetic Variation

Differences in genes or DNA segments among individuals within a population.

Sexual selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

IntrAsexual selection

A form of natural selection in which there is direct competition among individuals of one sex for mates of the opposite sex.

IntErsexual selection

A form of natural selection in which individuals of one sex are choosy in selecting their mates from the other sex; also called mate choice.

Intron

A noncoding, intervening sequence within a eukaryotic gene.

Exon

A sequence within a primary transcript that remains in the RNA after RNA processing.

Nucleotide variability

Genetic variation at the level of DNA nucleotides.

Gene variability

Genetic variation at the level of a gene.

Variant

A form or version of something that differs in some respect from other forms of the same thing or from a standard.

Disruptive selection

Natural selection in which extreme values for a trait are favored over intermediate values.

Directional selection

Natural selection in which one extreme phenotype is favored over the other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

Mass extinctions

The extinction of a large number of species within a relatively short period of geological time. macroevolution

Frequency dependent selection

Selection in which the fitness of a phenotype depends on how common it is in the population.

Balancing selection

Natural selection that maintains two or more phenotypic forms in a population.

Founder effect

Genetic drift that occurs when a FEW individuals become isolated from a larger population and form a new population whose gene pool is not reflective of the original population.

Bottleneck effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

Gene duplication

The multiplication of a particular gene in the genome.

Point mutation

A mutation affecting only one or very few nucleotides in a gene sequence.

Coevolution

The joint evolution of two interacting species, each in response to selection imposed by the other. macroevolution

Hardy-Weinberg equilibrium

The state of a population in which frequencies of alleles and genotypes remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work.

Adaptative radiation

The evolution of many diversely adapted species from a common ancestor. macroevolution

Punctuated equilibrium

In the fossil record, long periods of apparent stasis, in which a species undergoes little or no morphological change, interrupted by relatively brief periods of sudden change. macroevolution

Developmental gene changes

Changes in the genes that regulate development and thus contribute to major evolutionary changes. macroevolution

Biological species concept

Definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.

Reproductive isolation

The existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring.

Morphological species concept

Definition of a species by body shape and other structural features.

Ecological species concept

Definition of a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.

Niche (ecology)

The sum of a species' use of the biotic and abiotic resources in its environment.

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.

Geographic isolation

The separation of two populations of the same species or breeding group by a physical barrier, such as a mountain or body of water.

Polyploidy

the presence of extra sets of chromosomes, more common in plants than in animals. 

Autopolyploid

An individual that has more than two chromosome sets that are all derived from a single species.

Allopolyploid

A fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combining their chromosomes.

Habitat Differentiation

Sympatric speciation can also result from the appearance of new ecological niches. For example, the apple maggot fly can undergo sympatric speciation.

Zygote

The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg.

Hybrid

Offspring that result from the mating of individuals from two different species or from two true-breeding varieties of the same species.

Prezygotic reproductive isolation

A reproductive barrier that impedes mating between species or hinders fertilization if interspecific mating is attempted.

Post-zygotic reproductive isolation

A reproductive barrier that occurs after members of two different species have mated and produced a hybrid zygote.

Habitat isolation

PREzygotic barrier; Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers.

Temporal isolation

PREzygotic barrier; Species that breed during different times of day, different seasons, or different years cannot interbreed.

Behavioral isolation

PREzygotic barrier; Courtship rituals and other behaviors unique to a species are effective barriers to mating.

Mechanical isolation

PREzygotic barrier; Morphological differences prevent successful mating.

Reduced hybrid viability

POSTzygotic barrier; The genes of different parent species may interact and impair the hybrid's development or survival in its environment.

Hybrid breakdown

POSTzygotic barrier; First-generation hybrids are fertile, but subsequent generations lose fertility.

Reduced hybrid fertility

POSTzygotic barrier; Even if hybrids are vigorous, they may be infertile.

Hybrid zone

A geographic region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.

Hybrid reinforcement

Natural selection strengthens prezygotic barriers to reproduction, thus decreasing the chances of hybrid formation.

Hybrid stability

Hybrids continue to be produced.

Hybrid fusion

The reproductive barriers weaken and the two species fuse into a single species.

Punctuated equilibrium speciation model

Speciation occurs rapidly and is followed by long periods of stasis.

Gradual equilibrium speciation model

Speciation occurs gradually over long periods of time.

Orthologous genes (orthologs)

omologous genes that come from the same ancestral species, and are found in a variety of the descendants.    Ex.: primates share gene sequences 

Paralogous genes (paralogs)

homologous genes that result from gene duplication.  

Studies have found that one of the duplicated genes may retain the original function, and the other may adopt new functions, leading to evolutionary change

Phylogenies

trace patterns of shared ancestry between species or groups of organisms

Pleisomorphy

a primitive trait or character state shared by a group of organisms, inherited from a common ancestor. ex/ vertabrate in chordates. shared with other taxa.

Apomorphy

a derived trait or character state that is newly evolved and not present in a common ancestor. ex/ hair in mammals. not shared, unique to taxa

Synapomorhpy

a shared derived trait that is present in some, but not all, members of a group, indicating a closer evolutionary relationship among those members. ex/ no tail in homids. shared by 2 taxa

Parasite

helminthes. → tapeworm

Protozoa

plasmodia → malaria

Fungi

Tinea → athlete’s foot

Prokaryote

bacteria → leprosy

Virus (NON-LIVING)

HIV → AIDS