A quick review Taxon: generally refers to any named group of organisms, such as species, genus, family, order, etc.. Node: represents the hypothetical ancestor Branches: lines diverging from a node Root: oldest divergence of a phylogenetic tree Terminal branch: most recently evolved taxa Polytomy: unresolved node, multiple descendents A quick review C 5 C 6 1
Species Concepts Morphological Species - A population or group of populations that differs morphologically from other populations. Evolutionary Species A single lineage of populations or organisms that maintains its identity from other such entities and has its own evolutionary tendencies and historical fate. Phylogenetic Species - an irreducible cluster of organisms, within which there is a parental pattern of ancestry and descent, and which is diagnosably distinct from other such clusters Biological Species - Group of natural populations that is reproductively isolated from other such groups, but in which the component populations are not reproductively isolated Species Concepts Morphological Species - A population or group of populations that differs morphologically from other populations. Evolutionary Species A single lineage of populations or organisms that maintains its identity from other such entities and has its own evolutionary tendencies and historical fate. Phylogenetic Species - an irreducible cluster of organisms, within which there is a parental pattern of ancestry and descent, and which is diagnosably distinct from other such clusters Biological Species - Group of natural populations that is reproductively isolated from other such groups, but in which the component populations are not reproductively isolated 2
Species Concepts Morphological Species - A population or group of populations that differs morphologically from other populations. Evolutionary Species A single lineage of populations or organisms that maintains its identity from other such entities and has its own evolutionary tendencies and historical fate. Phylogenetic Species - an irreducible cluster of organisms, within which there is a parental pattern of ancestry and descent, and which is diagnosably distinct from other such clusters Biological Species - Group of natural populations that is reproductively isolated from other such groups, but in which the component populations are not reproductively isolated Species Concepts Morphological Species - A population or group of populations that differs morphologically from other populations. Evolutionary Species A single lineage of populations or organisms that maintains its identity from other such entities and has its own evolutionary tendencies and historical fate. Phylogenetic Species - an irreducible cluster of organisms, within which there is a parental pattern of ancestry and descent, and which is diagnosably distinct from other such clusters Biological Species - Group of natural populations that is reproductively isolated from other such groups, but in which the component populations are not reproductively isolated 3
Species Concepts Morphological Species - A population or group of populations that differs morphologically from other populations. Evolutionary Species A single lineage of populations or organisms that maintains its identity from other such entities and has its own evolutionary tendencies and historical fate. Phylogenetic Species - an irreducible cluster of organisms, within which there is a parental pattern of ancestry and descent, and which is diagnosably distinct from other such clusters Biological Species - Group of natural populations that is reproductively isolated from other such groups, but in which the component populations are not reproductively isolated Biological Species Concept Emphasis is on isolation of gene flow Isolation in fishes 4
Example from last weekend Mobile basin Ecologically similar Morphologically similar Similar Range Similar habitat use Numerous contact zones Duvernell, D.D., Meier, S., Schaefer, J.F., and Kreiser, B.R. 2013. Contrasting Phylogeographic Histories Between Broadly Sympatric Topminnows in the Fundulus notatus species complex. Molecular Phylogenetics and Evolution doi: 10.1016/j.ympev.2013.07.013. 5
Black Creek Pascagoula River F. notatus F. olivaceus Hybrid (F1/introgressed) Are the hybrids viable? Probability of Spawn (% +/- 1SE) 0.5 0.4 0.3 0.2 0.1 0.0 F=39.6, P<0.001 a b a a Hatching Success (%, +/- 1SE) 0.8 0.6 0.4 0.2 0.0 a a b F=12.9, P<0.001 b -0.1 Pure F 1 Hybrid Backcross Type of Cross F 2 Hybrid -0.2 Pure F1 Hybrid Backcross Type of Cross F 2 Hybrid Sort of. Are these species? 6
Speciation Allopatric: Sympatric: A A A Parapatric: A A+A A A Three Spined Stickleback Marine and freshwater forms distinct Marine form - planktivore Freshwater: Inhabit post-glacial lakes - <15,000 yrs Three freshwater forms Benthic form Planktivore form Intermediate form 7
Hypothesized Evolutionary History Glaciers recede, lakes formed, marine form invades Selection pressure different in lakes, generalist form uses all lake habitats second marine invasion Benthic and zooplanktivore specialists replace intermediate form and marine form. Morphological Adaptations in Stickleback 8
Hypothesized Evolutionary History Experimental Evidence Marine forms survival greater when mixed with benthic forms Marine forms eat more zooplankton when mixed with benthic forms = more competition with intermediate forms 9
Stickleback Summary Marine Form Invades Freshwater Freshwater Intermediate Invades Freshwater Freshwater Intermediate + Marine Benthic Planktivore Biogeography Study of the distribution of organisms: Isolating mechanisms variable by taxa. 10