Integrative taxonomy

Integrative taxonomy

Gustav Paulay

Florida Museum of Natural History

University of Florida

Integrative taxonomy

• Use of multiple lines of evidence

• Field - museum - lab

• Ecology - behavior - morphology - genetics - geography

• Distinguishing between morphs and species

• Two or more independent characters showing distinction between species

Integrative taxonomy:

Actinopyga mauritiana - guamensis

Integrative taxonomy:

Actinopyga mauritiana - guamensis

Not seeing species where there are

• cukes vs. primates – different foci for sensory perception

• unequal rates of evolution– phenotype: morphology, behavior, color pattern...– genotype: sequence divergence– reproductive isolation

Supposed distribution of Scutellastra flexuosa and exusta

Powell, 1968

but what is really going on...

NJ K2P COI

Seeing species where there aren’t

• ecophenotypic variation

• ontogenetic variation

• geographic variation

• ecological variation - depth, habitat, etc

• polymorphism

• paralogous loci

• former divergence now united

Paralogous loci:mitochondrial

genes gone nuclear in Alpheus

Williams & Knowlton 2001 Mol Biol Evol

Cypraea tigris a species differentiated, then

united

ESU - reciprocal monophyly

• DNA - gene flow - BSC

• reciprocal monophyly implies lack of recent genetic connections

• need several samples of each form to test

• reliability of conclusion depends on depth of intra- vs. inter-specific variation

• in sympatry - separate biological species

• in allopatry - separate ESUs, species status subjective

Basinal/subbasinal speciation common

• perceived as other dominant mode of speciation by past studies

• predominant mode in Cypraeidae, Aspidochirotida, Diogenidae, Parribacus

Cypraea punctata complex

Where are the species limits?

Lack of reciprocal monophyly

• morphs rather than species

• distinct species, but:– introgression– insufficient time for sorting

• deep coalescent

• rapid speciation

Introgression in Astralium

Introgression in Bohadschia argus?• Unusual form only in W Pacific; never seen in Polynesia, etc.

• Need compare independent markers to test

Insufficient time for sorting

Gene trees vs. species trees:

coalescence theory

Avise 1999 Phylogeography

Evolution of reproductive isolation

• Slow– most gastropod– deep divergence among allopatric ESUs– clear reciprocal monophyly– slow to secondary sympatry / biological species

• Rapid– echinoids, holothuroids– shallow divergence among sympatric species– potential paraphyletic species– rapid to secondary sympatry / biological species

1. Two deeply divergent clades: A & B

sympatric on 8 island groups

2. 30 ESUs so far

3. Pigmentation separates major and minor

clades.

Astralium rhodostomum complex

Geographic signal

no signal0

5

10

15

20

25

30

35

40

0 4 8 12

16

20

24

28

32

36

40

44

48

52

56

60

64

68

72

76

80

84

88

Ma

# E

SE

s

structure no structure

94% divergences < 10 Maretain signal (115 of 122)

Persistence of allopatry - Cypraeidae

94% divergences < 10 Maretain allopatry (115 of 122)

Echinometra mathaei complex Rapid secondary sympatry

Facilitated by rapid evolution of fertilization proteins?

~1 MaCOIBindin

Landry et al. 2003 Proc Roy SocCOI

Bindin

Cukes like urchins:Actinopyga obesa complex

Stichopus variegatus complex

Advantages of sequence data

• Directly test genetic connections

• Very large number of characters

• Independent markers - independent sources

• “Independent” of morphology - so can trace evolution of form, etc on gene tree without circularity

Potential problems with sequence data

• depth of coalescent vs. interspecific divergence

• paralogous sequences

• introgression– selective sweeps– homogenization through drift