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Host-Parasite Cospeciation. Key Questions Is the parasite an heirloom or a souvenier? Is the association ancient or recent? What processes are involved?

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Presentation on theme: "Host-Parasite Cospeciation. Key Questions Is the parasite an heirloom or a souvenier? Is the association ancient or recent? What processes are involved?"— Presentation transcript:

1 Host-Parasite Cospeciation

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5 Key Questions Is the parasite an heirloom or a souvenier? Is the association ancient or recent? What processes are involved? Is there coevolution? Is there correlated evolution?

6 Coevolution: coadaptation and cospeciation Coadaptation = reciprocal adaptation Cospeciation = joint speciation of host and parasite

7 Farenholzs Rule Farenholzs rule - parasite phylogeny mirrors host phylogeny Implies we can use parasite phylogeny to infer host phylogeny

8 Modern Cospeciation Studies Construct host and parasite phylogenies independently. Test for cospeciation (dont assume it). Use molecular phylogenies so we can compare rates of evolution.

9 Incongruence signals processes other than cospeciation

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11 Testing hypotheses of cospeciation Would we get host and parasite phylogenies that are this similar due to chance alone? Can test using random trees: generate many (>100) random parasite trees and see how similar they are to the host tree.

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13 Lice as a model system Methods for comparing host and parasite phylogenies Comparative molecular evolution Factors involved in cospeciation Factors involved in host specificity

14 Genus Family Suborder Anoplura 532 Ischnocera 3,060 1,344 Amblycera bird mammal Kim, 1988 Paterson et al, 2000 Smith, 2000 Barker, 1991 Clayton et al, 1996 Page et al, 1995 Hafner et al, 1994 Lyal, 1985a Rhyncophthirina 2 Clay, 1969 Host:

15 Why lice are nice... Obligatory, permanent parasites Single host during life cycle Ectoparasites (easy to manipulate) High degree of cospeciation

16 Why lice are lousy... Single origin of parasitism No endoparasitic lice Single host during life cycle Not (very) virulent c.f. mites

17 Gophers and Lice O. hispidus T. bottae T. talpoides G. personatus G. breviceps G. bursarius (a) G. bursarius (b) C. merriami P. bulleri O. cavator O. cherriei O. underwoodi C. castanops O. heterodus Z. trichopus G. chapini G. setzeri G. thomomyus G. perotensis T. minor T. barbarae G. trichopi G. nadleri G. expansus G. geomydis G. oklahomensis G. ewingi G. texanus G. actuosi G. panamensis G. cherriei G. costaricensis

18 Swiftlets and Dennyus lice Chaetura pelagica Chaetura vauxi C. esculenta nitens C. esculenta bagobo C. esculenta marginata C. esculenta cyanoptila 1 C. esculenta cyanoptila 2 C. linchi A. elaphrus A. francicus A. spodiopygius assimilis 1 A. mearnsi A. vanikorensis palawanensis A. fuciphagus vestitus A. salanganus natunae A. spodiopygius assimilis 2 A. s. spodiopygius A. maximus lowi A. brevirostris vulcanorum A. terraereginae Cypsiurus balasiensis Cypsiurus parvus D. dubius D. vauxi Dennyus sp. 1 D. distinctus ssp. D.distinctus timjonesi D. d.distinctus D. somadikartai 1 D. somadikartai 2 D. carljonesi fosteri D. carljonesi forresteri D. hahnae D. c. carljonesi D. singhi D. kristinae D. wraggi D. simberloffi Dennyus sp. 2 D. wellsi D. thompsoni D.collinsi D. adamsae D. cypsiurus 1 D. cypsiurus 2

19 Song birds and Brueelia lice

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21 Correlated evolution Relative rates of molecular evolution Host and louse body size Host and parasite speciation rates

22 Relative rates of molecular evolution Molecular data is comparable between hosts and parasites (unlike morphological data) Can use homologous genes to compare rate of evolution (e.g., cytochrome oxidase I in birds and lice) Louse mitochondrial genes evolve 2-3 times more rapidly than bird and mammal genes

23 Louse metathoracic width (µm) ln (Host body mass in grams) Big birds have big lice

24 Head groove width correlates with hair width Groove Diameter of Chewing Louse (µm) Hair Diameter of Pocket Gopher (µm)

25 Replicate lineages Multiple parasites on the same host Can test hypotheses concerning patterns and processes

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28 Distribution of two louse genera

29 How do multispecies assemblages arise? Host species AHost species B head lice wing lice

30 Genus Family Suborder Anoplura 532 Ischnocera 3,060 1,344 Amblycera bird mammal Kim, 1988 Paterson et al, 2000 Smith, 2000 Barker, 1991 Clayton et al, 1996 Page et al, 1995 Hafner et al, 1994 Lyal, 1985a Rhyncophthirina 2 Clay, 1969 Host:

31 How old are lice w.r.t. their hosts?

32 Microraptor gui, an early Cretaceous feathered dinosaur

33 Fossil bird louse from Eocene (44 Mya)

34 Summary Host-parasite cospeciation is an instance of a more general problem (historical associations). We can use phylogenies for host and parasite to test hypotheses of cospeciation. Lice are an excellent group for cospeciation studies.


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