BIOL 191 Lecture: Evolution and Speciation

Vocabulary-style flashcards based on lecture notes for BIOL 191, covering fundamental principles of evolution, species concepts, reproductive barriers, modes of speciation, and evolutionary developmental biology.

Common descent with modification

The first key principle of Evolution stating that all life on Earth arose from a universal common ancestor through genetic inheritance and modification in successive generations.

Universal common ancestor

The organism from which all species evolved, estimated to have lived between $3.5$ and $3.8$ billion years ago.

Microevolution

Evolution on a small scale, referring to changes in allele frequencies within a population over a short time frame.

Macroevolution

Evolutionary changes that produce new species and groups of species over long periods of time.

Species

A group of related organisms that share a distinctive set of attributes in nature and an evolutionary history distinct from other species.

Natural selection

The process by which individuals with certain heritable traits are more likely to survive and reproduce, causing beneficial traits to become more common over many generations.

Genetic drift

A change in genetic variation from generation to generation due to random chance, which has a greater influence in a small population.

Migration

The movement of individuals and their alleles between populations which can change the allele frequencies of the recipient population.

Nonrandom mating

A phenomenon where individuals select mates based on phenotypes or genetic lineage; it alters genotype proportions but does not change allele frequencies.

Morphological species concept

A definition of species based on members sharing homologous physical characteristics, such as skull, teeth, skeleton, or leaf shape.

Cryptic species

Organisms that look physically alike but do not interbreed, such as the Gray and Cope's tree frogs which have different chromosome numbers.

Biological species concept

A definition proposed by Ernst Mayr stating that species are groups of interbreeding natural populations that are reproductively isolated from other such groups.

Evolutionary lineage species concept

A concept based on shared, derived characters (synapomorphies) where species are defined by their line of descent from an immediate ancestral species.

Ecological species concept

A definition by L. van Valen that identifies species based on their ecological niche, including the unique set of resources required and their influence on the environment.

General lineage species concept

A concept by K. de Queiroz that incorporates multiple criteria, including evolutionary relationships, reproductive isolation, and habitat requirements.

Reproductive isolating mechanisms

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

Prezygotic isolating mechanisms

Barriers that prevent the formation of a zygote, including temporal, behavioral, mechanical, and gametic isolation.

Temporal isolation

A prezygotic barrier where species are prevented from interbreeding because they breed at different times of the year or day.

Behavioral isolation

A prezygotic barrier where individuals fail to recognize or reject the mating behaviors, such as calls or rituals, of other species.

Mechanical isolation

A prezygotic barrier caused by differences in the sizes and shapes of reproductive organs that prevents successful mating.

Gametic isolation

A prezygotic barrier occurring when the sperm and eggs of different species are unable to fuse.

Postzygotic isolating mechanisms

Barriers that block the development of viable, fertile offspring after fertilization, including hybrid inviability, hybrid sterility, and hybrid breakdown.

Hybrid sterility

A postzygotic mechanism where an interspecies hybrid is viable but cannot reproduce, such as a mule ($2n = 63$) resulting from a donkey and a horse.

Allopatric speciation

A speciation process driven by geographic separation, leading to the accumulation of different mutations and eventually reproductive isolation.

Adaptive radiation

The rapid emergence of many species from a single common ancestor, often occurring when a population is introduced to a new environment with little competition.

Hybrid zones

Areas where separated populations can interbreed; outcomes include reinforcement (increased barriers), fusion (merging populations), or stability (maintained hybrid zone).

Sympatric speciation

Speciation that occurs without a geographical barrier, typically through local adaptations, polyploidy, or hybridization.

Polyploidy

The duplication of sets of chromosomes within individuals, occurring in $40-70 \%$ of plant species, which can produce a new species in a single generation.

Autopolyploidy

The duplication of chromosome sets within a single species.

Allopolyploidy

The combination of chromosome sets from two different species, which is the process that formed crops like wheat, cotton, and canola.

Evo-Devo

Evolutionary-developmental biology, which compares the development of different organisms to understand ancestral relationships and developmental mechanisms that drive evolutionary change.

Pattern formation

The process by which cell division, migration, differentiation, and death produce an organism with a specific body pattern.

BMP4

A cell-signaling protein that causes cells to undergo programmed cell death (apoptosis) during development, such as in the formation of chicken feet.

Gremlin

A protein that inhibits the function of BMP4, allowing cells to survive and resulting in features like the webbed feet of ducks.

Hox genes

Transcription factors that act as master controls for directing the formation of particular body regions along the anteroposterior axis.

Heterochrony

Evolutionary changes in the rate or timing of developmental events, leading to morphological differences such as the skull shapes of adult humans versus chimpanzees.