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Speciation

Outline

Species Defined

Speciation Mechanisms

The Challenge of Sympatry

Adaptive Radiations

Genetics of Speciation

Goal: Understand the utility and

limitations of species concepts,

explanations for the ecology and

genetics of speciation.

Species

Why does it matter?

What do we want out of

a species definition?

< 1000 across 14 roosts 30 yr

200,000 now Lesser Long Nosed Bat

Biological Species

Groups of potentially reproducing individuals that are distinct or isolated from other such individuals Emphasis is on genetic isolation from other groups Widely used …

Biological Species

Problems:

Doesn’t work for fossils Doesn’t work for asexuals What degree of isolation is allowed? Rare hybridization okay? What about greatly reduced fitness rather than zero fitness? Often difficult to test Watch extra video

Phenetic Species

trait one trait two More dimensions = Divergence trait three

Problems:

Evolutionary Convergence (may not reflect evolutionary history) How to weigh traits? Which traits to measure? Cutoffs are arbitrary

Ecological Species

Species are defined by their niche; competition is stronger within species than among them (or they could not coexist) Works for asexuals Has adaptive peak appeal

Shared, derived characters define the smallest possible monophyletic group Inherently evolutionary (ancestor/descendent)

Phylogenetic Species

Works for asexuals

Splitter/lumper effects with traits or How finely do you split groups?

Phylogenetic Species

Problems:

Tendency to inflate species number

Good luck applying this in nature

Problems:

Evolutionary Species

‘Fuzzy’ language Ancestor-descendent lineages that maintain their identity from others and that have their own evolutionary tendencies and fate Time A

A’

B A C

C

Species are the result of speciation events

Tautological Species

easy to apply allows you get on with more interesting things Species Speciation

Geographic isolation allows groups to differentiate

1. Allopatric Speciation

• differentiation occurs and reproductive isolation arises between isolated populations vicariance - physical barrier arises the divides population

Geographic isolation allows groups to differentiate

1. Allopatric Speciation

vicariance - physical barrier arises the divides population