Species concepts, reproductive isolation, speciation modes, macroevolutionary tempo.
Speciation And Macroevolution
Species concept
Operational definition of species. Biological species concept (Mayr): reproductively isolated populations. Phylogenetic: smallest…
Reproductive isolation
Barriers preventing interbreeding. Prezygotic: temporal, behavioural, mechanical, gametic isolation. Postzygotic: hybrid…
Allopatric speciation
Divergence in geographically separated populations accumulating genetic incompatibilities. Dominant mode in animals (Mayr). Classical:…
Sympatric speciation
Divergence within a single geographic area via ecological differentiation, sexual selection, or polyploidy. Documented in cichlid fish,…
Adaptive radiation
Rapid diversification of a lineage into multiple ecological niches. Canonical: Darwin's finches, Hawaiian honeycreepers, African rift-lake…
Mass extinction
Short interval of elevated extinction rate across many taxa. Big Five: Ordovician-Silurian, Late Devonian, Permian-Triassic (~96% marine…
Cambrian explosion
~540 Mya rapid diversification of most animal phyla. Causes debated: O2 rise, Hox-gene innovation, predation. Burgess Shale + Chengjiang…
Cope's rule & Dollo's law
Cope: lineages tend toward larger body size over time. Dollo: complex lost traits rarely re-evolve (irreversibility). Both are tendencies…
Background vs mass extinction
Raup & Sepkoski 1982: baseline extinction rate punctuated by ~5 mass-extinction peaks (end-Permian wiped ~95% of marine species).…
Hybrid zone
Geographic region where two diverged populations meet + interbreed. Tension zones maintained by selection against hybrids; can lead to…
Biological species concept (BSC) framework
Mayr 1942: a species is a group of actually or potentially interbreeding natural populations reproductively isolated from other such…
Haldane's rule framework
Haldane 1922: when in F₁ hybrids one sex is absent, rare, or sterile, that sex is the heterogametic one (XY in mammals, ZW in birds). …
BSC (Mayr 1942)
E Mayr 1942 biological-species-concept; modern Coyne-Orr 2004 'Speciation'; reproductive-isolation core.
Punctuated equilibrium (1972)
Eldredge-Gould 1972 punctuated-equilibrium; modern macroevolution Stanley 1979 species-selection.
Ring species
Mayr 1942 + Wake 1997 Ensatina; modern Irwin 2001 greenish warbler; rare but textbook case-studies.
Sympatric (Via 1999)
S Via 1999 sympatric-speciation review; modern Bolnick-Fitzpatrick 2007 conditions; cichlid-fish models.
Hybrid speciation (Mallet 2007)
J Mallet 2007 hybrid-speciation review; Heliconius butterflies homoploid + allopolyploid plants; modern 25% plant-hybrid.
Mass extinctions (Raup-Sepkoski 1982)
Raup-Sepkoski 1982 'big-five' extinctions; modern 6th anthropogenic + Permian-Triassic largest 96% marine.
BSC (Mayr 1942)
E Mayr 1942 'Systematics and the Origin of Species' biological-species-concept; modern modern foundational text + 2024 genomic-species…
Dobzhansky (1937)
T Dobzhansky 1937 'Genetics and the Origin of Species'; modern modern foundational text + DM-incompatibility + 2024 hybrid-fitness…
Tempo (Simpson 1944)
G G Simpson 1944 'Tempo and Mode in Evolution'; modern modern foundational + adaptive-radiation + 2024 phylogenetic-comparative methods…
Punc-eq (Eldredge-Gould 1972)
N Eldredge-S J Gould 1972 punctuated-equilibrium; modern modern foundational text + 2024 quantitative-test of saltational-vs-gradual…
Hybrid zone (Barton-Hewitt 1985)
N Barton-G Hewitt 1985 hybrid-zone analysis; modern modern foundational text + 2024 genomic-cline + Heliconius wing-pattern…
Ecological speciation (Rundle-Nosil 2005)
H Rundle-P Nosil 2005 ecological-speciation review; modern modern foundational + 2024 sticklebacks + Heliconius + Rhagoletis fly host-race.