The Origin of Species Review Flashcards

Flashcards covering vocabulary and key concepts of speciation, reproductive barriers, and evolutionary models according to the Chapter 13 lecture notes.

Taxonomy

The science of naming and classifying species.

Taxa

A general term, plural of taxon, referring to a group of organisms belonging to any taxonomic rank.

Species (Phylogenetic concept)

Recognizable geographic forms with unique evolutionary histories; particularly useful for systematists.

Species (Biological concept)

Defined by Ernst Mayr in 1942 as actually or potentially interbreeding populations which are reproductively isolated from other such groups.

Species (General lineage concept)

Metapopulations of organisms that evolve independently from other metapopulations.

Metapopulation

A group of spatially separated populations of the same species with some level of gene flow between them.

Isolating barriers

Mechanisms that prevent gene flow between species, maintaining species distinctions.

Allopatry

A condition where populations are geographically separated from one another.

Sympatry

A condition where populations or species occur in the same geographic area.

Interspecific

Occurring between different species.

Intraspecific

Occurring within the same species.

Pre-zygotic barriers

Reproductive barriers that occur before mating (e.g., timing, pollinators, courtship rituals) or after mating but before fertilization.

Gametic incompatibility

A post-mating, pre-zygotic barrier where sperm or pollen from one species fails to penetrate and fertilize the egg of another species.

Post-zygotic barriers

Reproductive barriers that occur after fertilization, such as hybrid embryos failing to develop, hybrid sterility, or lower fitness.

Reinforcement

The evolution of additional reproductive barriers that can complete the process of speciation when groups with weak barriers come back into contact.

Sympatric speciation

The divergence of a population into two or more populations divided by reproductive barriers while living in the same geographic area, often involving non-random mating.

Ecological speciation

The evolution of reproductive barriers as a result of adaptations to different environments or niches.

Extirpated

The state of being locally extinct.

Aneuploidy

A chromosomal change where one chromosome breaks or fuses with another, changing the number of chromosomes by one.

Polyploidy

A chromosomal change resulting in an additional set of chromosomes; common in plants (70-80% of extant flowering species).

Autopolyploidy

A duplicated set of chromosomes derived from the same species.

Allopolyploidy

A duplicated set of chromosomes created by adding those of a different species.

Cryptic species

Species that look alike but are genetically distinct, often discovered through DNA sequencing.

16S rRNA

A slowly evolving gene used for a ribosomal RNA molecule that is helpful in identifying microbial species and lineages.

Core genome

A small fraction of genes found in every strain of a prokaryote species, inherited from a common ancestor.

Pan-genome

The collection of all genes found in all strains of a species.

Horizontal gene transfer

The transfer of genetic material between individuals within the same generation, common in bacteria and archaea via plasmids.

Stable ecotype model

A concept where microbes undergo ecological speciation and can be sorted into genetic and ecological clusters based on narrow niches (e.g., specific temperature or light levels).