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Bio1B Evolution 9Last lecture:Evolution of sacrifice (altruism)Species & speciation• What is a species anyway? (Pp. 487-492)

– Concepts - typological, biological, phylogenetic– Reproductive isolation - mechanisms

TodaySpecies & speciation• What is a species anyway? (Pp. 487-492)

– Interesting one - Ensatina salamanders– Easy one? - Humans & living relatives

• Speciation processes (Pp 492-504)

• Introduction & geographic modes• Adaptive radiations• Hybridization - hybrid zones, reinforcement & hybrid-

speciation

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Species of Hominidae

Pygmychimp

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Ensatina eschscholtzii - One ring species? Or 2biological species? Or >11 Phylogenetic species

k-e overlap;no hybrids

k-e overlap;hybrids

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Geographic modes of speciation

Futuyma 2005

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exiguus

aenigma

bombiens

saxatilis

concinnus

monticola

hosmeri

exiguus v aenigma• 5% mtDNA divergence

• Large body size & lowerfreq. call in aenigma

concinnus v monticola• 5% mtDNA divergence

•concinnus has lower & longercall, distinct morphology

Allopatric sister species among northern, montane Cophixalus (Hoskin 2004)

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Parapatric evolution ofreproductive isolation overa very short distance in the

grass speciesAnthoxanthum odoratum

Futuyma 2005

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Sympatric speciation on remote islands:eg. Lord Howe Island palms (Howea) Savolainen et al. 2006 Nature

441:210-214

Recently (<1Mya) formedsister species - ecologicallydistinct and with divergentflowering time - despite highgene flow across the range ofeach species on the island

Calcareous soilsFlowering time

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Peripatric speciation: paradise-kingfishersin New Guinea (Mayr)

Futuyma 2005

Processes: Founderevent, drift, selection?

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Adaptive radiations (pp. 524-5)

• Rapid speciation withecologically-drivendivergent selection

• Common on remoteislands or other novelenvironmentsfollowing colonization

• Promoted by isolation& ecologicalopportunity

e.g. Hawaiian silverswords(Fig. 25.18)

Other examples: African cichlids,Hawaiian arthropods, Andeanlupines, Carribean anole lizards etcetc

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Speciation onislands:Losos &Rickleffs

2009

Adaptivedivergenceamong or

within islands

Adaptive divergenceof bill dimensions

leng

th

width & depth

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Hybrid zones - alternative outcomesafter re-contact between lineages

Or, new “hybrid species”Fig. 24.14

Or - lineages don’t hybridizeand eventually overlap ifecologically distinct