bio140 exam 1

Vocabulary flashcards covering key terms and definitions from the Population Genetics, Origin of Species, Evidence for Evolution, Origins of Life, and Systematics lecture notes.

Autotrophs

Organisms that produce their own fuel molecules using energy from inorganic sources.

Heterotrophs

Organisms that absorb or ingest nutrients from the environment.

Photoautotrophs

Organisms that use sunlight as their energy source to produce food.

Chemoautotrophs

Organisms that derive energy from chemical reactions to synthesize fuel molecules.

Photosynthesis

A metabolic process that uses light energy to produce food.

Carbon Fixation

The process of incorporating inorganic carbon molecules into organic molecules.

Nitrogen Fixation

The process of incorporating nitrogen into a biologically available form.

LUCA

Last Universal Common Ancestor; the ancestral organism from which all life on Earth arose.

Desiccation

Extreme drying or the complete loss of water from an organism.

Binary Fission

A method of asexual division in prokaryotes and eukaryotic organelles like mitochondria and chloroplasts.

Protists

A diverse group of eukaryotic organisms present in all eukaryotic supergroups, united only by not being plants, animals, or fungi.

Pseudopodia

Cytoplasmic extensions ('false feet') serving as the chief means of locomotion for amoebas.

Phagotrophs

Heterotrophic protists that ingest particulate food matter.

Mixotrophs

Organisms that combine phototrophic and heterotrophic modes of nutrition.

Schizogony

A form of asexual reproduction in which the nucleus divides repeatedly before the cell divides into multiple daughter cells.

Cyst

A dormant cell protected by a resistant outer coating.

Genetic Variation

Differences in versions of genes (alleles) found in individuals of a population.

Evolution

Genetic change in a population over generations, resulting as the outcome of genetic change through time.

Allele

Different forms of a gene.

Homozygous

Having two identical copies of the same allele (e.g., BB).

Heterozygous

Having two different alleles for a given gene (e.g., Bb).

Dominant Allele

An allele that is expressed in the phenotype even when only one copy is present (e.g., B).

Recessive Allele

An allele that is expressed in the phenotype only when two copies are present (e.g., b).

Phenotype

The physical appearance or observable expression of a trait.

Genotype

The underlying genetic makeup of a trait (e.g., PP, pp, Pp).

Blending Inheritance

An incorrect historical concept suggesting that offspring inherit traits as a perfect, intermediate average of their parents' phenotypes.

Gene Flow

The movement of alleles from one population to another through immigration or emigration, increasing genetic diversity.

Nonrandom Mating

A condition where individuals choose mates based on specific traits rather than at random.

Assortative Mating

A form of nonrandom mating where individuals choose partners with similar phenotypes, increasing the proportion of homozygous individuals.

Disassortative Mating

A form of nonrandom mating where individuals choose partners with different phenotypes, increasing the proportion of heterozygous individuals.

Genetic Drift

Random fluctuations in allele frequencies that occur by chance in small populations, which can lead to the loss of alleles.

Founder Effect

A form of genetic drift occurring when one or a few individuals establish a new, isolated population, altering allele frequencies.

Bottleneck Effect

A form of genetic drift resulting from a drastic reduction in population size due to environmental events or human activities, causing a loss of genetic variability.

Natural Selection

A process where environmental conditions determine which individuals produce the most offspring, leading to evolutionary adaptation.

Artificial Selection

A process in which humans selectively breed organisms for desired characteristics.

Fitness

An organism's ability to survive and reproduce, successfully passing its genes to the next generation.

Parental Investment

The energy and time each sex invests in producing and raising offspring.

Sexual Selection

A form of natural selection operating through competition for mates.

Intrasexual Selection

Direct competition among members of one sex for mating access to the opposite sex (e.g., male-male fighting).

Intersexual Selection

Mate choice where individuals of one sex (typically females) actively choose mates based on specific traits (e.g., selecting flashier males).

Negative Frequency-Dependent Selection

Selection favoring rare phenotypes over common ones, making rare alleles more common and maintaining genetic variation.

Positive Frequency-Dependent Selection

Selection favoring common phenotypes over rare ones, which tends to eliminate genetic variation.

Oscillating Selection

Selection that favors one phenotype at one time and a different phenotype at another time in response to changing environmental conditions.

Heterozygote Advantage

A situation where heterozygous individuals have higher fitness than homozygous individuals, maintaining both alleles in a population.

Disruptive Selection

Selection acting on quantitative traits that favors individuals at both extremes while eliminating intermediate phenotypes.

Directional Selection

Selection acting on quantitative traits that favors individuals at one extreme while eliminating individuals at the other extreme.

Stabilizing Selection

Selection acting on quantitative traits that favors intermediate phenotypes while eliminating both extreme phenotypes.

Isotope

An alternate form of an element containing the same number of protons but a different number of neutrons.

Half-Life

The time required for half of a sample of a parent radioactive isotope to decay into daughter products.

Homologous Structures

Anatomical structures derived from a common ancestor that share structural similarities, though they may vary in appearance or function.

Vestigial Structures

Structures with no apparent current function that resemble functional structures possessed by ancestors.

Pseudogenes

Traces of previously functioning genes remaining in the genome after the corresponding trait has been lost.

Convergent Evolution

The independent evolution of similar features in distantly related lineages adapting to similar environments and selective pressures.

Biogeography

The study of the geographic distribution of species across the planet.

Industrial Melanism

The evolutionary adaptation where organisms in heavily polluted industrial regions develop darker pigmentation to avoid predation.

Relative Dating

Determining the relative age of rock layers and fossils based on their vertical position (deeper layers are older, higher layers are younger).

Isotopic Dating

Determining the absolute age of rocks and fossils based on the known, constant decay rate of radioactive isotopes.

Sympatric

Organisms or species occupying the same geographic area that remain distinct phenotypically and behaviorally.

Allopatric

Populations or species that are geographically separated by physical barriers.

Zygote

A single diploid cell resulting from the fusion of male and female gametes (fertilized egg).

Reproductive Isolation

A state in which two populations cannot interbreed or do not produce fertile, viable offspring.

Gamete

A haploid reproductive cell, such as a sperm or an egg.

Reinforcement

The process by which natural selection strengthens incomplete reproductive isolating mechanisms until populations are fully isolated.

Polyploidy

A condition in which an organism possesses more than two complete sets of chromosomes.

Polymorphism

The presence of two or more distinct phenotypic forms within a single species population.

Biological Species Concept

Defines a species as groups of interbreeding natural populations that are reproductively isolated and produce fertile offspring.

Prezygotic Isolating Mechanisms

Reproductive barriers that prevent the formation of a zygote between species.

Postzygotic Isolating Mechanisms

Reproductive barriers that prevent proper functioning or fertility of hybrid zygotes after fertilization.

Ecological Isolation

A prezygotic barrier where species inhabit different microhabitats within the same geographic area and rarely encounter one another.

Behavioral Isolation

A prezygotic barrier where species differ in mating courtship rituals, visual, auditory, or chemical signals.

Temporal Isolation

A prezygotic barrier where species reproduce at different times of day, different seasons, or different years.

Mechanical Isolation

A prezygotic barrier where physical or anatomical differences prevent successful mating or pollen transfer.

Ecological Species Concept

Proposes that species are maintained by stabilizing selection as they adapt to distinct ecological niches.

Autopolyploidy

Polyploidy where all duplicated chromosomes originate from a single species, leading to tetraploids.

Allopolyploidy

Polyploidy resulting from hybridization between two different species followed by spontaneous chromosome doubling.

Adaptive Radiation

The rapid evolution of a single ancestral species into a group of diverse, closely related species adapted to different environmental niches.

Character Displacement

An evolutionary process where competing species divergence in physical or behavioral traits to minimize resource competition.

Gradualism

An evolutionary model describing slow, continuous accumulation of small genetic changes over extended geological time.

Punctuated Equilibrium

An evolutionary model characterized by long periods of evolutionary stasis interrupted by brief periods of rapid change.

Systematics

The scientific study of evolutionary relationships among organisms.

Phylogeny

A hypothesized evolutionary history and set of relationships among a group of species.

Node

A point on a phylogenetic tree representing a divergence event where a single lineage split into two distinct lineages.

Cladistics

A systematic method of constructing evolutionary trees based on shared derived character states.

Ancestral Characteristic

A trait present in an entire analyzed group that was inherited from a common ancestor of that group.

Derived Characteristic

An evolutionary trait that arose recently and is shared only by a subset of a larger group.

Outgroup

A species closely related to, but outside, the group of interest, used as a baseline to determine ancestral character states.

Cladogram

A branching diagram generated by cladistic analysis that visually depicts a hypothesis of evolutionary relationships.

Clade

A monophyletic group consisting of a common ancestor and all of its descendants sharing derived characteristics.

Principle of Parsimony

A rule stating that the preferred phylogenetic tree hypothesis is the one requiring the fewest evolutionary changes or assumptions.

Molecular Clock

A molecule that accumulates genetic changes at a relatively constant rate, used to estimate divergence times between lineages.

Classification

The practice of placing species and higher taxonomic groups into an organized hierarchy.

Taxonomy

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

Taxon

A named group at any level of the biological classification hierarchy (e.g., species, family, domain).

Monophyletic Group

A taxonomic group consisting of a most recent common ancestor and all of its descendants.

Paraphyletic Group

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

Polyphyletic Group

A taxonomic group containing species with similar traits that does not include the most recent common ancestor of all members.

Homoplastic Structures

Anatomically similar features that evolved independently in separate lineages and were not inherited from a common ancestor.