Speciation, Cladograms, and Comparative Genomics

Vocabulary flashcards covering speciation mechanisms, species concepts, phylogenetic trees, cladograms, and comparative genomics based on lecture notes.

Macroevolution

The process, also known as speciation, where microevolution accumulated over hundreds of thousands of generations results in a new species.

Biological species concept (BSC)

A concept defining a species as a group of organisms that can mate naturally and produce fertile offspring.

Mule

The viable but usually infertile offspring resulting from a cross between a horse (gamete with $32$ chromosomes) and a donkey (gamete with $31$ chromosomes), giving the mule $63$ chromosomes that cause complications during meiosis.

Phylogenetic species concept (PSC)

A concept defining species using DNA sequencing and comparison, where organisms belonging to the same species possess highly similar DNA sequences.

Allopatric speciation

Speciation resulting from geographical isolation, where a population is separated by a physical barrier (such as water, mountains, or desert) and evolves independently.

Sympatric speciation

The formation of a new species within the same geographical area as a result of physical, behavioural, or genetic reproductive isolation.

Polyploidy

A condition resulting from failed meiosis where diploid gametes form tetraploid offspring, serving as a primary mechanism of sympatric speciation in plants.

Taxonomy

The naming and classification of living organisms based on evolutionary relationships.

Cladograms

Qualitative family trees constructed using derived characteristics and shared traits, in which branch length has no meaning.

Phylogenetic trees

Evolutionary trees constructed using genetic or protein sequence alignment to quantify relatedness, where branch length is proportional to relatedness.

Ultrametric trees

Phylogenetic trees calibrated based on mutation rates to estimate the time since species shared a common ancestor, where branch length is proportional to time.

Node

A branch point on a cladogram or phylogenetic tree representing a common ancestor for all downstream organisms sharing a specific feature.

Taxon

The named organism or group located at the end of a branch on a cladogram or phylogenetic tree (plural: taxa).

Comparative genomics

The study involving the sequencing, alignment, and comparison of orthologous chromosome regions, genes, or proteins to infer evolutionary relationships.

Orthologous sequences

Similar or homologous DNA or protein sequences occurring between different species that are aligned and compared to identify historical mutations.