Chapter 10: Darwin's First Question - The Origin of Species

Vocabulary flashcards covering key concepts, mechanisms, and examples of speciation from Chapter 10 of Carl Zimmer's textbook.

Biological Species Concept (BSC)

A concept coined by Ernst Mayr in 1942 defining a species as a group of actually or potentially interbreeding populations that are reproductively isolated from other such groups.

Allopatry

A mode of speciation where geographical barriers, such as mountains or rivers, physically separate populations and prevent interbreeding.

Sympatry

A mode of speciation occurring when populations inhabit the same geographic area, but interbreeding is prevented by biological or behavioral barriers.

Reinforcement

The process where natural selection acts to strengthen reproductive isolation between diverging populations, such as through mate discrimination to avoid producing sterile hybrids.

Ring Species

A connected series of neighboring populations around a geographic barrier where adjacent populations interbreed, but populations at the extreme ends of the range overlap and behave as separate species.

Alloploidy

A form of polyploidy where a hybrid organism contains two or more sets of chromosomes derived from two different parent species.

Horizontal Gene Transfer (HGT)

The movement of genetic material between non-parent-offspring organisms, commonly incorporating foreign DNA stretches directly into a recipient microbe's genome.

Pan-genome

The total set of all genes found across all analyzed strains or lineages within a microbial species.

Core-genome

The conserved set of genes that is present in every strain of a particular microbial species.

16S rRNA Criterion

A phylogenetic threshold in microbiology where a microbe is classified as a new species if its 16S rRNA gene sequence is less than $97\%$ identical to any known species.

Cryptic Species

Species that appear morphologically similar or identical as adults, but are proven by molecular DNA analysis and larval or ecological differences to be distinct species.

Tragopogon

A genus of flowering plants (salsify flowers) that exhibits rapid speciation through allopolyploidy.

Rhagoletis

A genus of fruit flies in the northeastern United States that underwent sympatric speciation by specializing on introduced apple trees versus native hawthorn trees.