Bi 1e Final Exam Study (for my pookie Ezra)

origin of life

The process by which living organisms rose from non living matter, transitioning independent entities into integrated biological systems.

LUCA Last Universal Common Ancestor

The most recent common ancestor from which all organisms now living on Earth share a common genetic plot.

early metabolism

The primordial biochemical pathways that sustained early life before the evolution of complex enzymatic systems.

endosymbiosis

A mutually beneficial relationship where one organism lives inside the body or cell of another, leading to organelles like mitochondria and chloroplasts.

eukaryotic origins

The evolutionary transition involving endosymbiosis and increased cellular complexity that led to the domain Eukarya.

multicellularity

The evolutionary transition from single celled organisms to integrated, multicellular systems with specialized cells.

major evolutionary transitions METs

Key events in evolutionary history where independent entities integrate into a higher level biological system.

mitochondria

An organelle derived via endosymbiosis that functions as the powerhouse of eukaryotic cells.

chloroplasts

An organelle derived via endosymbiosis responsible for photosynthesis in plants and algae.

multicellular organisms

Complex life forms composed of multiple cells that cooperate to function as a single integrated system.

eusocial insect colonies

Superorganisms like ants or bees where individual behaviors emerge into a higher level social system.

mutation

A random change in the genomic sequence of an organism, serving as the raw material for evolution.

genetic drift

Random fluctuations in allele frequencies over time, which can drive evolution non adaptively.

natural selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

effective population size Ne

The size of an ideal population that experiences the same rate of genetic drift as the actual population.

neutral evolution

Evolutionary changes in alleles that are neutral with respect to fitness, often driven by genetic drift rather than selection.

constructive neutral evolution CNE

A process where complex structures or dependencies evolve through neutral mutations and genetic drift rather than adaptive selection.

transposable elements

DNA sequences that can change their position within a genome, contributing to genome complexity and mutation rates.

genome complexity

The structure, organization, and size of an organism's genetic material, which is not always driven by adaptation.

symbiotic entrenchment

A process where a host becomes evolutionarily dependent on a symbiotic partner over time.

Bauplan

The generalized structural body plan or architectural blueprint common to a group of animals.

segmentation

The division of an animal body plan into repetitive linear segments, allowing for modular evolution.

selector genes

Genes whose expression determines the developmental fate of specific groups of cells or body segments.

Hox genes

A conserved group of homeotic selector genes that control the anterior posterior body axis patterning in animals.

homeosis

The transformation of one body part into another due to developmental rewiring.

homeotic mutations

Genetic mutations that cause one developmental structure or appendage to be replaced by another.

morphogens

Signaling molecules that diffuse through tissues to form a concentration gradient, guiding spatial cell differentiation.

compartment boundaries

Lineages of cells within developing tissues that do not mix, establishing distinct spatial domains.

imaginal discs

Sac like structures in insect larvae that undergo rapid growth and transformation into adult appendages during metamorphosis.

scaling

The relationship between the size of an organism or body part and its functional or physical properties.

organ growth

The developmental process regulating the size and cell proliferation of specific body structures.

Hippo pathway

A highly conserved signaling pathway that restricts organ size and controls cell proliferation.

InR TOR signaling

An intracellular pathway that senses nutrient availability to regulate metabolism, organ growth, and body scaling.

sensorimotor pathways

Neural circuits that link sensory inputs, such as smell or taste, directly to motor outputs and behaviors.

olfaction

The sense of smell, driven by highly modular neural systems that can expand and evolve.

neural circuits

Interconnected networks of neurons that process information and generate specific behavioral outputs.

odorant receptors ORs

A large family of chemoreceptors responsible for detecting airborne volatile molecules.

ionotropic receptors IRs

A class of chemical receptors that function as ligand gated ion channels involved in sensory processing.

gustatory receptors GRs

Chemoreceptors responsible for taste and detecting chemical cues in the environment.

nervous system evolution

The historical modification and elaboration of neural architectures from simple networks to complex brains.

social evolution

The evolutionary study of behaviors that have fitness consequences for both the actor and recipients, leading to group complexity.

modularity of behavior

The organization of behavior into independent, evolvable motifs that can be rewired or co opted.

collective behavior

Complex group actions that emerge from simple rules followed by individual organisms without central coordination.

eusociality

A highly structured social system characterized by cooperative brood care, overlapping generations, and a division of labor into reproductive and non reproductive castes.

emergent systems

Complex higher level structures or behaviors that arise from local interactions among simpler modular units.

QTL mapping of behavioral traits

Quantitative Trait Loci analysis used to identify specific genomic regions linked to complex behaviors.

independently evolvable behavioral motifs

Distinct, modular units of behavior that can change across generations without disrupting other behavioral traits.

biological species concept

A definition of species based on groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

phylogenetic species concept

A definition of species as the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent.

reproductive isolation

Biological barriers that prevent different species from producing viable, fertile offspring.

premating isolation

Barriers that prevent mating or fertilization from occurring between different species, such as behavioral or ecological differences.

postzygotic isolation

Barriers that occur after fertilization, resulting in hybrid inviability, sterility, or breakdown.

hybrid incompatibility

Genetic mismatches in hybrid offspring that lead to reduced fitness, sterility, or death.

hybrid sterility

A postzygotic barrier where hybrid offspring are viable but cannot produce functional gametes.

hybrid lethality

A postzygotic barrier where hybrid embryos fail to develop or survive to reproductive age.

introgression

The movement of genetic material from one species into the gene pool of another through repeated backcrossing.

hybrid speciation

The formation of a new, distinct species through the hybridization of two parental species.

reinforcement

The process where natural selection increases premating isolation between two populations in response to costly hybrid incompatibility.

key innovations

Novel adaptive traits that allow a lineage to exploit new ecological niches, often driving rapid adaptive radiations.

contingency

The principle that macroevolutionary outcomes depend heavily on unique, historical events and chance occurrences.

convergence

The independent evolution of similar phenotypic features in distinct lineages facing similar ecological pressures.

parallel evolution

The independent evolution of similar traits starting from a similar ancestral condition or genetic background.

sign epistasis

A genetic interaction where the fitness effect of a mutation changes from positive to negative depending on the presence of other mutations.

potentiation

An evolutionary step where prior neutral or weakly beneficial mutations set the stage for a major subsequent innovation.

historical constraint

Limitations on future evolutionary trajectories imposed by an organism's unique phylogenetic history and inherited genetic architecture.

evolutionary constraints

Restrictions on the range of possible phenotypic variations that can evolve due to developmental, physical, or genetic limitations.

modularity

The organization of biological systems into discrete, semi independent units that can evolve and vary without disrupting the whole.

co option

The evolutionary process by which an existing gene, pathway, or structure is repurposed for a novel function.

hierarchical organization

The nested structure of life where genes, cells, tissues, organisms, and societies form interconnected levels of complexity.

constraints

The physical, developmental, and historical limits that prevent evolution from being infinitely flexible.

emergence

The manifestation of complex properties at a system level arising from simple, localized interactions.

selective sweep

The rapid increase in frequency and eventual fixation of a beneficial mutation, reducing genetic variation in nearby genomic regions.

purifying selection

Selection that eliminates deleterious mutations from a population to preserve genomic integrity.

balancing selection

A type of selection that maintains multiple alleles or genetic variants in a population over long periods.

positive selection

Selection that favors and accelerates the spread of beneficial alleles through a population.

relaxed selection

The reduction or elimination of selective pressures on a trait, often leading to decay or constructive neutral evolution.

stabilizing selection

Selection that favors intermediate phenotypes by acting against extreme phenotypic variations.

transposable elements

Self replicating DNA sequences that jump across the genome, driving structural mutations and complexity.

ortholog vs paralog

Genes in different species that evolved from a common ancestral gene via speciation versus genes related by duplication within a genome.

gene duplication

An evolutionary event that produces an extra copy of a gene, providing raw genetic material for divergence.

subfunctionalization

The split of a duplicated gene's ancestral functions between the two new daughter copies.

neofunctionalization

The evolutionary process where one copy of a duplicated gene acquires an entirely new function.

dN dS

The ratio of nonsynonymous to synonymous substitution rates, used to estimate selective pressures on protein coding sequences.

homeotic mutation

A mutation that causes the transformation of one developmental segment or body structure into another.

allometry

The differential growth of body parts in relation to the total size of the organism.

cis regulatory evolution

Evolutionary changes occurring in non coding DNA sequences like enhancers that alter gene expression timing or location.

enhancer evolution

Modifications to cis regulatory elements that drive novel spatial or temporal expression of conserved genes.

glomerulus

A spherical structure in the olfactory bulb where synapses form between olfactory receptor neurons and downstream circuits.

QTL mapping

A statistical method that links phenotypic traits with genetic markers to locate chromosomal regions influencing quantitative traits.

Hamiltons rule

An inequality defining when altruistic behaviors are favored by selection based on genetic relatedness and fitness costs and benefits.

kin selection

An evolutionary strategy that favors the reproductive success of an organism's relatives, even at a cost to the organism's own survival.

Burgess Shale fauna

A famous fossil assemblage that captures the explosive diversification of complex and unusual animal body forms during the Cambrian.

Opabinia

An extinct stem group arthropod from the Cambrian known for its five eyes and long proboscis, exemplifying high morphological disparity.

Wiwaxia

A soft bodied Cambrian organism covered in scales and spines, key to discussions about contingency and early animal evolution.

Stephen Jay Gould

The evolutionary biologist who championed the concept of historical contingency and popularized the metaphor of replaying the tape of life.

replaying the tape of life

A thought experiment exploring whether re running the history of life would lead to similar or vastly different biological outcomes.

Antennapedia

A Drosophila Hox gene mutant where legs develop in place of antennae due to homeotic misexpression.

Ultrabithorax

A Hox gene that specifies the identity of the third thoracic segment in Drosophila, causing a four winged mutant when disrupted.

Drosophila Hox mutants

Classic genetic models demonstrating how altering single selector genes can radically modify body plans.

Drosophila courtship song QTLs

Specific genetic regions identified as drivers of variation in behavioral song motifs among fruit flies.