Speciation and Evolutionary Processes in Biology

Speciation

The process by which new species arise, involving genetic isolation and divergence.

Biological species concept

Different species are reproductively isolated and do not interbreed or fail to produce offspring capable of surviving/reproducing.

Reproductive isolating mechanisms (RIMs)

Mechanisms that prevent species from interbreeding.

Prezygotic isolation

Individuals of different species are prevented from successfully mating.

Postzygotic isolation

Individuals of different species can mate, but their offspring aren't viable or can't reproduce.

Temporal isolation

A type of prezygotic isolation where species breed at different times.

Mechanical isolation

A type of prezygotic isolation where physical differences prevent mating.

Behavioral isolation

A type of prezygotic isolation where differences in mating behaviors prevent mating.

Habitat isolation

A type of prezygotic isolation where species live in different habitats and do not meet.

Gamete incompatibility

A type of prezygotic isolation where sperm and egg meet but do not fuse.

Hybrid inviability

A type of postzygotic isolation where individuals can mate, but the offspring do not survive.

Hybrid sterility

A type of postzygotic isolation where individuals can mate and produce offspring that survive, but the offspring can't reproduce.

Morphological species concept

Species differ in size, shape, or other morphological features.

Polymorphic species

When one species is incorrectly split into two based on different phenotypes.

Cryptic species

Species that can't be identified by their morphology.

Phylogenetic Species Concept

Defines a species as the smallest monophyletic group based on evolutionary history.

Synapomorphies

Homologous traits unique to a monophyletic group.

Allopatric speciation

Speciation that begins with geographic isolation.

Genetic isolation

No gene flow due to geographic isolation.

Dispersal

Occurs when individuals colonize a new habitat.

Vicariance

Occurs when a physical barrier separates a widespread population.

Sympatric speciation

Speciation that occurs without geographic separation.

Polyploidization

A condition in which an organism has more than 2 sets of complete sets of chromosomes.

Autopolyploidy

Self, error in meiosis, e.g., maidenhair ferns.

Allopolyploidy

Mating of two species with different chromosome numbers followed by an error in mitosis that duplicates the offspring chromosomes.

Theory of Chemical Evolution

The idea that simple chemical compounds combine to form complex carbon compounds, leading to the first proto-cell.

Elements of life

Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).

Sources of energy on early earth

Solar radiation, electrical discharges from lightning, heat from volcanic eruptions, and natural radioactivity.

Prebiotic soup model

Organic compounds essential for life forms were synthesized in the primitive Earth under prebiotic conditions.

Prebiotic or primordial soup

The mixture of inorganic and organic compounds with water on the primitive Earth.

Surface metabolism model

Dissolved gases + minerals in deep sea vents, more concentrated (smaller area), Acetic acid may have acted as a catalyst.

Difference between DNA and RNA

DNA carries instructions for cells to grow, function, & replicate; RNA carries out the instructions & makes proteins.

RNA World Hypothesis

RNA can replicate and evolve.

Characteristics of RNA

Single stranded; More reactive than DNA.

Microevolution

Changes in populations over 'short' periods of time.

Macroevolution

Changes in species over long periods of time.

Phylogenetics

The study of the evolutionary history of life, fossil record.

Parsimony

The most likely explanation/pattern is the one that requires the least amount of change.

Homology

Due to common ancestry (shared derived trait).

Homoplasy

Due to convergent evolution.

Convergent evolution

The independent evolution of similar traits in different species due to similar environmental conditions/ways of life.

Monophyletic clade

A grouping of species that includes a single common ancestor and all its descendants.

Shared derived characters

They're based on a single common ancestor and are useful in establishing a phylogeny.

Universal tree of life

Supported by Cell Theory and the Theory of Evolution by natural selection, suggesting all species trace back to a single common ancestor.

Fossilization process

Organism dies, quickly buried (sediment, volcanic ash, tar, amber), soft tissues decay, hard tissues mineralize, sediment is compacted into rock, rock is exposed by erosion or excavation.

Four biases of the fossil record

Habitat, Taxonomic/tissue, Temporal, Abundance.

Adaptive radiation

One species forced to adapt, one lineage rapidly diverges, leading to many descendant species with a wide range of adaptive forms.

Cambrian Explosion

A key feature and evidence of rapid adaptive radiation.

Prokaryotes

Unicellular organisms that reproduce asexually (via binary fission), lack a nucleus and membrane-bound organelles.

Morphology of prokaryotes

Includes spherical (coccus), rod (bacillus), and spiral shapes.

Motility in prokaryotes

Some, but not all bacteria & archaea move by means of flagella or gliding.

Gram-negative bacteria

Includes groups such as cyano and proteo.

Gram-positive bacteria

Includes groups such as actin and firmicutes.

Oxygenic photosynthesis

Performed by cyanobacteria, which were the first organisms to increase O2 levels on Earth.

Genetic diversity in prokaryotes

Contributed by metabolic diversity.