Taxonomy, Evolution, Genetics, and Speciation Flashcards

Comprehensive vocabulary flashcards covering key terms and concepts from the biology lecture notes on taxonomy, evolutionary mechanisms, population genetics, and speciation.

Taxonomy

The science of identifying, classifying, and naming living organisms.

Binomial nomenclature

A system of two-part scientific names for organisms consisting of a capitalized genus name and a lower-case species name, both italicized or underlined (e.g., Alliaria petiolata).

Archaea

One of the three domains of life, comprising single-celled organisms in a single kingdom.

Bacteria

A domain of single-celled prokaryotic organisms lacking membrane-bound organelles.

Eukarya

A domain containing organisms whose DNA is enclosed in a nucleus and possess membrane-bound organelles, including plants, animals, fungi, and protists.

Taxon

A single level or group within the hierarchical taxonomic classification system (Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species).

Phylogenetic tree

A diagram that illustrates the hypothesized evolutionary relationships and history among organisms or groups of organisms.

Node

A branch point on a phylogenetic tree representing the splitting of a taxon or a single lineage into distinct new ones.

Sister groups

Two lineages or groups that are most closely related because they diverged from the same node or branch point.

Outgroup

A taxon on a phylogenetic tree that is distantly related to the focus taxa being studied.

Monophyletic group

Also known as a clade; a group consisting of a single common ancestor and all of its descendants without excluding any.

Paraphyletic group

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

Polyphyletic group

A group of organisms derived from two or more distinct ancestors that does not include the true common ancestor of all its members.

Polytomy

A node on a phylogenetic tree with more than two branches, representing uncertainty or lack of data in evolutionary relationships.

Homologous structures

Parallel physical features across diverse organisms that share a similar form because they were inherited from a common ancestor (e.g., human, dog, bird, and whale forelimbs).

Analogous structures

Characteristics that are functionally or visually similar across species due to convergent evolution under similar selective pressures, rather than shared ancestry.

Vestigial organs

Physical structures present in an organism that have lost their original function over evolution, such as nonfunctional eyes in cave bats.

Natural selection

The differential survival and reproduction of individuals based on inherited adaptations in their present environment, leading to increases in favorable traits over generations.

Absolute fitness

The total number of offspring produced by a specific genotype, calculated as $\text{proportion of survival} \times \text{fecundity}$.

Relative fitness

An individual's or genotype's reproductive success relative to the reference genotype with the highest fitness in a population, calculated as $R_i = \frac{F_i}{F_r}$.

Pax6

A homologous control/regulatory gene in vertebrates that encodes proteins responsible for directing eye form and development.

Hardy-Weinberg Model

A null baseline model describing population allele frequencies assuming no natural selection, assortative mating, mutation, migration, and an infinite population size.

Genetic drift

The random effect of chance on a population's gene pool, causing allele frequencies to fluctuate over generations independently of natural selection.

Bottleneck effect

A magnification of genetic drift that occurs when a natural disaster or extreme event dramatically reduces the size of a population.

Founder effect

An event initiating an allele frequency change when a small group branches off or becomes isolated from the main population.

Inbreeding depression

An increase in abnormalities, rare recessive traits, and reduced reproductive performance caused by mating among closely related individuals.

Allopatric speciation

Speciation that occurs when populations are geographically separated by a physical barrier such as a mountain range or the Isthmus of Panama.

Sympatric speciation

Speciation that occurs within the same geographic area without physical isolation, driven by factors like temporal differences, resource use, or competition.

Parapatric speciation

Speciation occurring when neighboring populations split into distinct groups along an environmental gradient or cline, often forming a hybrid zone.

Cline

A gradual geographical variation across an ecological gradient, such as temperature, elevation, precipitation, or nutrients.

Adaptive radiation

A process where a single species rapidly diversifies into several distinct species to fill empty ecological niches.

Prezygotic barrier

A reproductive isolation mechanism that prevents mating or fertilization from occurring prior to zygote formation.

Postzygotic barrier

A reproductive isolation mechanism that acts after fertilization, leading to unviable offspring, low fitness, or sterile hybrids.

Stabilizing selection

A pattern of natural selection that favors average phenotypes and narrows overall phenotypic variation in a population.

Directional selection

A pattern of natural selection where environmental changes favor phenotypes at one end of the spectrum of variation, shifting the distribution.

Diversifying selection

Also known as disruptive selection; selection that favors two or more distinct phenotypes, increasing overall genetic variability.

Coevolution

Reciprocal evolutionary changes between two or more interacting species (antagonistic or mutualistic) driven by natural selection.

Handicap principle

A theory of sexual selection proposing that only the fittest individuals can afford costly physical ornaments or behaviors.

Good genes hypothesis

A theory of sexual selection stating that individuals develop impressive ornaments to demonstrate an efficient metabolism or disease resistance.

Cladistics

A method of organizing homologous traits to reconstruct phylogenetic trees and determine evolutionary timelines.

Maximum parsimony

The concept that the most likely order of evolutionary events is the simplest path requiring the fewest evolutionary steps or divergences.

Horizontal gene transfer (HGT)

The transfer of genetic material between unrelated species rather than vertical inheritance from parent to offspring.