Lab Exam 1 Study Guide Flashcards

Comprehensive vocabulary terms and definitions translated from the Lab Exam 1 Study Guide covering Natural Selection, Hardy-Weinberg, Darwin's Finches, and Cladistics.

Microevolution

Small-scale changes in allele frequencies within a single population over a short period.

Macroevolution

Large-scale evolutionary patterns above the species level over vast geological timeframes, leading to new taxonomic groups.

Natural Selection

The differential survival and reproduction of individuals due to differences in phenotype, leading to shifts in genetic makeup over time.

Frequency

The proportion or percentage of a specific component (like an allele, genotype, or phenotype) relative to the whole population.

Chromosome

A long, thread-like structure composed of DNA and proteins that carries genomic genetic information.

Ploidy

The number of complete sets of chromosomes present in a cell or organism (e.g., haploid, diploid).

Mendelian Inheritance

Patterns of inheritance obeying Gregor Mendel's laws (segregation and independent assortment), where traits are determined by discrete alleles.

Locus

The specific physical location of a gene on a chromosome.

Allele

A specific variant or version of a gene at a particular locus.

Dominant allele

An allele expressed in the phenotype even if only one copy is present ($Ww$ or $WW$), masking the effects of a recessive allele.

Recessive allele

An allele masked by dominant alleles; only expressed in the phenotype if two copies are present ($ww$).

Homozygous

Describes an individual having two identical alleles at a specific locus (e.g., $GG$ or $gg$).

Heterozygous

Describes an individual having two different alleles at a specific locus (e.g., $Gg$).

Population

A group of individuals of the same species living in the same area at the same time.

Species

A broader group of organisms that can potentially interbreed to produce fertile offspring.

Genotype

The genetic makeup or combination of alleles an organism carries.

Phenotype

The observable physical or behavioral traits resulting from the genotype (e.g., flower color, leaf texture).

Sexual Selection

A type of natural selection driven by mate choices, favoring traits that maximize an individual's chances of securing a mate, even if it hinders survival.

Hardy-Weinberg equilibrium

A state where allele frequencies remain constant and stable generation to generation, assuming no mutation, random mating, no selection, large population size, and no gene flow.

Genetic drift

The random fluctuation of relative allele frequencies at a locus in a small population.

Biological Species Concept (BSC)

Defines a species as a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

Cryptic Species

Two or more distinct species that look virtually identical morphologically but are genetically distinct and reproductively isolated.

Sexual Dimorphism

Clear differences in physical appearance (color, size, structure) between males and females of the same species.

Speciation

The evolutionary process by which a single ancestral lineage splits into two or more distinct descendant species.

Anagenesis

Direct, linear evolution of a single lineage over time without branching.

Cladogenesis

Branching evolution where an ancestral species splits into multiple distinct species.

Prezygotic barriers

Reproductive barriers that prevent a hybrid zygote from forming, such as different behaviors or mating seasons.

Postzygotic barriers

Reproductive barriers that act after fertilization, where the hybrid forms but is sterile or inviable.

Maximum Frequency

The highest pitch reached during a bird song.

Vocal Deviation

How far a bird song falls short of the physical performance limit, resulting from the trade-off between trill speed and bandwidth.

Allopatric speciation

Speciation triggered by physical geographic isolation.

Sympatric speciation

Speciation occurring within the same shared geographic area without physical isolation.

$$R^2$$

An indicator of correlation strength on a graph; values close to $1$ are strong with tightly clustered points, while values close to $0$ are weak with highly scattered points.

Syrinx

A specialized vocal organ located at the base of the trachea used by birds to produce songs.

Branch

The lines on a phylogenetic tree representing evolutionary lineages changing over time.

Node

Splitting points on a phylogenetic tree representing a common ancestor where lineages diverge.

Taxa

The terminal ends or tips of a phylogenetic tree representing the organisms being classified.

Root

The baseline branch representing the earliest common ancestor of all organisms on a phylogenetic tree.

Synapomorphy

A shared, derived (newly evolved) character state present in a common ancestor and all its descendants, used to define clades.

Symplesiomorphy

A shared, ancestral (primitive) character state inherited from a distant, ancient ancestor.

Autapomorphy

A unique derived character state found in only one single terminal taxon.

Homoplasy

A shared trait that evolved independently in separate lineages due to convergent evolution or reversals, rather than shared ancestry.

Monophyletic group

An evolutionary group containing a common ancestor and all of its descendants (a true clade).

Paraphyletic group

A group containing a common ancestor and some, but not all, of its descendants.

Polyphyletic group

A group of distantly related organisms that excludes their most recent common ancestor.

Maximum Parsimony

A principle used to select a tree from a character matrix by choosing the one with the lowest score or fewest evolutionary steps.