BIO120: Evolution

Evolution

The theory that living things change over time, and adapts through natural selection, changes are natural and not instantaneous, lineages split by speciation, results in generational biodiversity, all species share a common ancestor

Biodiversity

Diversity of all life on Earth; kind of organisms in a given area

Adaption

Any trait that makes an organism survive or reproduce in a given environment

Adaption Process

Any evolutionary processes that lead to adaptation; focus on evolutionary history (patterns) and mechanisms (processes) which are oftentimes interconnected

Microevolution

Evolutionary patterns and processes observed within species

Macroevolution

Evolutionary patterns and processes observed among species

Evolutionary History

Determine the evolutionary relationships of organisms in terms of common ancestry; identify and understand long-term patterns in evolution

Evolutionary Mechanisms

"Determine the particular processes responsible for evolutionary change; identify the major forces of evolution

Paley's Theory

Stemmed from theology; compared the tree to a watch rather than a rock since "both have function," and thus evolution came from function

Lamarck's Theory

Provided a hypothesis for the causal mechanism: the inheritance of acquired characteristics; thinks that as time passes, species get more and more complex linearly

Darwin's Theory

First to propose that evolution came from natural selection through mechanisms such as variation, heritability, and differential fitness, and that those changes are gradual and dynamic

Variation

Individual variation in a population

Heritability

Progeny resemble their parents more than unrelated individuals

Differential Fitness

Some forms are more successful at surviving and reproducing than others in a given environment (fitness refers to the ability to survive and adapt and pass genes onto the next generation, not your physical fitness)

Homology

Similarity of traits in two or more species that is due to inheritance from a common ancestor

Vestigial Structures

Features inherited from an ancestor, but reduced in morphology and function; can only be explained by the presence of functional traits in ancestors, followed by evolutionary degradation

Homologous Structures

Organismal features that are consistent with modifications of pre-existing structures; fundamental structural similarity reflects common ancestry but evolved to serve different functions

Analogous Structures

Biological structures having similar or corresponding functions but not from the same evolutionary origin

Domestication

An evolutionary process by which animals are artificially selected and undergo huge phenotypic behavioral and physiological alterations

Antibiotic Resistance

When microbes evolve mechanisms that protect them from antimicrobials, which are drugs used to treat infections

Genotype

Genetic constitution of an organism; defined in relation to a particular gene or gene combinations

Phenotype

Feature of the organism as observed; used when discussing a trait of an organism that varies

Genome

The entirety of an organism's DNA (which includes genes and non-coding regions)

Mutation

An inevitable phenomenon that is nondirectional; a stable change in the DNA sequence, occurs at a low rate, but rate varies in ways that are partially predictable (can be neutral, beneficial, or deleterious)

Point Mutations

A type of mutation where one coding base is changed, changing only the specific amino acid that is encoded for

Insertions/Deletions

A mutation in which a codon is inserted or deleted, changing the code of the amino acids after it

Repetitions

A mutation where the number of repetitions are changed

Chromosomal Rearrangements

A mutation in which the coding sequence is inverted

Silent Mutations

A mutation in which even though a base changes, the same amino acid is still encoded for

Nonsense Mutations

A mutation in which a change in the base encodes for a stop codon

Missense Mutations

A mutation in which a change in the base changes one or more amino acids in the sequence

Independent Assortment

In which different genes independently separate from one another during the formation of reproductive cells

Recombination

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

Preformationism

Spermists/ovists believed only one parent contributed to inheritance

Theory of Blending Inheritance

Theory where the offspring is an intermediary between mother and father

Mendelian Inheritance

A discrete form of inheritance with two locuses and dominant/recessive traits; 3:1 ratio

Continuous Variation

A non-Medelian form of inheritance in which more than two locuses are involved, hence encoding for more than two phenotypes

Malthus

Came up with the theory of population that theorized that population increased exponentially and food/resources increased arithmetically; and when the population threshold surpasses the resource one, some sort of extinction event will reset the population

Genetic Drift

Term we use when we randomly subsample alleles in a population; it is a change in the frequency of an existing gene variant (allele) due to random chance

Negative/Purifying Selection

Mutations that reduce fitness are removed by natural selection; decreases genetic variation in populations, decreases diversity

Positive/Directional Selection

Mutations that increase fitness will eventually become fixed in a population, decreases genetic variation in populations, thus decreasing diversity; eventually, you will get to a point where every or almost every single member of that population will have a copy of that allele

Fixation

Occurs when a polymorphic locus becomes a monomorphic due to the boss of all but one allele (can occur due to natural selection or genetic drift)

Selection Favouring Diversity

Natural selection can act to maintain diversity over the long term; increases (or retains) genetic variation in populations

Migration

Occurs when an individual from one population is sharing alleles with an individual from another population, influences the structuring of diversity over a large spatial scale, decreases differences between populations, but increases genetic diversity in populations (due to new genes)

Gene Flow

Movement of genetic information from one individual to another

Heterozygosity

In which an individual has two (or more if non-Mendelian inheritance) alleles encoding for a specific trait

Polymorphism

When there are two or more possibilities of a trait on a gene

Mutation-Selection Balance

Less fit types reintroduced by mutation, followed by selection acting to remove them

Selection Maintaining Variation

Heterozygote advantage, frequency‐dependent selection, fitness varies in space or time, umbrella term "balancing selection"

Classical School of Population Variation

Characterized by: Low heterozygosity, low polymorphism, wild type is "normal" genotype

Balance School of Population Variation

Characterized by: High heterozygosity, high polymorphism, heterozygote advantage

Gel Electrophoresis

A method for separation and analysis of biomacromolecules and their fragments, based on their size and charge; evidence for allozymes

Allozymes

Different allelic forms of the same protein

Selection Neutrality

Different types do not differ in their fitness relative to one another, new mutations neither eliminated nor retained by selection

Neutral Theory

Negative selection rapidly eliminates detrimental mutations, positive selection rapidly fixes beneficial mutations, the only mutations left to create genetic variation are selectively neutral

Asexual Reproduction

One parent contributes genetic material, no meiotic reductive, offspring clones of the parents

Sexual Reproduction

Two parents contribute genetic material to offspring, meiotic, reductive division to form gametes, fusion of gametes

Costs of Meiosis

The asexual female would contribute her genetics twice as much as the sexual female; asexual reproduction maintains favorable combinations of alleles while sexual reproduction can continually re-create unfavorable combinations of alleles

Costs of Sex

Time and energy to find and attract mates, increased energetic costs of mating, risk of predation and infection, cost of producing males, 50% less genetic transmission, break up of adaptive gene combinations such as segregation and recombinations

Benefits of Sex

Favorable combinations of mutations brought together more rapidly by sex, it can bring together favorable mutations and eliminate harmful mutations since sexual reproduction allows for independent assortment and recombination, benefits of genetic variation in variable/unpredictable environments

Tangled Bank Hypothesis

A model which predicts that sexual reproduction will be favored over asexual reproduction under conditions of scarce resources

Red Queen Hypothesis

The theory in which in order for a species to maintain a particular niche in an ecosystem and its fitness relative to other species, that species must be constantly undergoing adaptive evolution

Parthenogenesis

A natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization

Clonal Propogation

A method of asexual reproduction that creates genetically identical copies of a plant from a single individual

Outbreeding

Breeding with those one is not closely related to; mates are less closely related than random

Inbreeding

Breeding with those one is more closely related to; mates are more closely related than random

Outcrossing

Mating with someone else either by outbreeding or inbreeding; a fusion of gametes from two parents; games derive from meiotic reductive division

Selfing (Self-Fertilization)

Mating with yourself (which is only possible in hermaphrodites which are common in plants); most extreme form of inbreeding

Inbreeding Avoidance

In plants timing offset between male and female mechanisms as well morphological and physiological mechanisms, and dispersal and delayed maturity in animals

Effects of Inbreeding

Increases homozygosity, decreases heterozygosity, more prone to disease because of intermixing

Inbreeding Depression

The reduction in fitness of inbred offspring compared to outcrossed offspring; they have lower viability (survival) and lower fertility (reproductive output)

Fitness

Genetic contribution of individuals to the next generation, relative to other individuals, as a result of differences in viability and fertility

Selective Advantage

The amount by which some individuals of a given genotype are better adapted to a given environment

Artificial Selection

Selection by humans towards a goal

Natural Selection

Selection by abiotic and biotic environment, no "goal," effects all organisms

Stabilizing Selection

Favored traits are in the middle of the bell curve, changes the distribution of the traits by making the bell curve narrower (greater proportion of population will have a phenotype close to the mean)

Directional Selection

Favored traits will be on one end of the bell curve, changes the distribution of the traits by making the bell curve shift in one direction

Disruptive Selection

Opposite of stabilizing selection, favoured traits are the ones in the extremes (both ends of the bell curve and not the middle)

Population

A community of animals, plants, or humans among whose members interbreed

Stochastic

Unpredictable or random evolutionary forces, examples include mutation, recombination, genetic drift

Deterministic

Evolutionary forces which can be predicted somewhat, an example is natural selection

Population Bottleneck

A single sharp reduction in abundance, usually followed by rebound, causes a loss of diversity

Founder Event

Colonization by a few individuals that start a new population, colonizing group contains only limited diversity compared to the source population

Isolation by Distance

Accumulation of local genetic variation due to geographically limited dispersal

Phenotypic Plasticity

The ability of a genotype to modify its phenotype in response to a particular environment

Taxonomic Concept

Based primarily on distinct measurable differences

Biological Concept

Based on inter‐fertility among individuals

Geographic Isolation

The physical separation of populations of a species due to geographical barriers, such as rivers, mountains, or oceans

Reproductive Isolation

The inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

Intrinsic Post‐zygotic Barriers

Inviability, sterility, or abnormal development of hybrids

Extrinsic Post‐zygotic Barriers

Ecological mismatch of hybrid phenotype to environment

Adaptive Radiation

The evolution of ecological and phenotypic diversity within a rapidly multiplying lineage

Ecological Opportunity

The absence (or reduction) of competition for resources, colonization of competition‐free regions, extinction, key innovation

Hybridization

The exchange of genes between species as a result of occasional inter‐species mating

Polyploidy

Describes an organism, tissue, or cell with more than two complete sets of homologous chromosomes

Allopolyploidy

Arises from duplicated karyotype following hybridization between species

Autopolyploidy

Arises from duplicated karyotype within a species

Taxonomy

The theory and practice of classification & naming

Systematics

The study of biodiversity and the evolutionary relationships among organisms

Taxon

A single named taxonomic unit at any level, classified from kingdom, phylum, class, order, family, genus, species