Lecture 4

Lecture 4 - 2/14/11 What is a species? 2/14/11 What are...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 2/14/11 What is a species? 2/14/11 What are species? 1) Species and speciation: terminology 2) Different species concepts 3) Biological species concept in more detail 4) Speciation as a process and the relationships amongst species concepts 5) Diagnosing species 2/14/11 Terminology Reproductive isolation : when populations are unable to produce viable fertile offspring (i.e. a barrier to gene flow) Geographic isolation : populations are physically isolated from other populations by distance or barrier. Subspecies (also races, ecotypes): differentiated forms / populations which have not yet been designated full species status 2/14/11 Terminology (continued) Hybridization: interbreeding between differentiated populations or species, can lead to introgression (movement and incorporation of genes from one population into to other) Monophyletic group : A group that includes ALL of the descendants of a common ancestor. A B A B Not monophyletic A A B B Monophyl etic 2/14/11 Species concepts Endless source of debate Numerous, numerous concepts exist (at least 40) Species can be defined in a way that: 1) Enables classification (taxonomy) 2) Corresponds to discrete groups of organisms 3) Helps us understand how discrete groups arise (process) 4) Represent products of evolutionary history (history) 5) Applies to the widest array or organisms These goals do not always coincide, and one species concept is unlikely to serve all (or even most) of these purposes 2/14/11 Morphological species concept Species are groups of organisms that look really different from one another Darwins original species concept, heavily criticized yet still works ok today 2/14/11 Genotypic cluster species concept (GCSC) Species are distinct genetic clusters, separated by few or no intermediates Genetic extension of Darwins morphological species concept Problem: what is few or no? How many loci need to show this pattern? gene 1 gene 2 2/14/11 Phylogenetic species concept (PSC) A species is the smallest monophyletic group of common ancestry Species are exclusive groups of organisms, where an exclusive group is one whose members are all more closely related to one another than to any organism outside the...
View Full Document

Page1 / 40

Lecture 4 - 2/14/11 What is a species? 2/14/11 What are...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online