AERIAL ANCESTORS?
Page 1: Blood Brothers

CASE STUDY IN MOLECULAR EVOLUTION NO. 2
Written by Harold B. White, Sept 1995, revised July 2000
C-667 BIOCHEMICAL EVOLUTION, FALL 2013

Welcom to Kourosh's Home Page
Microchiroptera
Megachiroptera 
(Grey-headed flying fox)
As with other questions relating to human evolution, there is controversy about the relationship of primates to other mammalian orders (1,2,3). It is generally agreed that Chiroptera (bats) and primates are sister groups; however, things aren't so simple. There are two major subdivisions of bats: the large diurnal vegetarian Megachiroptera (fruit bats and flying foxes of the Old World) and the smaller, nocturnal, often insectivorous Microchiroptera (typical bats found in Delaware). Based on a number of characteristics, some evolutionists have suggested that the Megachiroptera are actually more closely related to primates (including us) than they are to the Microchiroptera. For example, fruit bats and primates are unable to synthesize ascorbic acid (4,5). In addition, the anatomy of the nerve connections between the eye and the midbrain are very similar while that of the Microchiroptera is typical of other mammals (6, but see 7). If these are primitive traits for the groups, it suggests either that humans had a flying ancestor or that flight evolved twice, once in each bat lineage. The aerial ancestor controversy was debated in Systematic Zoology (8-11).

Sometimes a comparison of amino acid sequences of orthologous proteins from the groups involved can resolve phylogenetic relationships. The amino acid sequences of the alpha- and beta-globin subunits of hemoglobin from representative micro- and megachiropterans have been determined and compared to those from human (12, 12a, 12b).

Focus Question: If you had the amino acid sequences of the both subunits of hemoglobin from the two types of bats and from humans, how would you go about comparing them?  How would you use that information to deduce the phylogenetic relationships among the three organisms? How would you represent the three (or four) possible phylogenies for humans and the two types of bats?

References:

1. Martin, R. D. (1990) Some relatives take a dive. Nature 345, 291-292.
2. Goodman, B. (1991) Holy phylogeny! Did bats evolve twice? Science 253, 36.
3. Novacek, M. J. (1992) Mammalian phylogeny: shaking the tree. Nature 356, 121-125.
4. Burns, J. J. and Evans, C. (1956) The synthesis of L-ascorbic acid in the rat from D-glucuronolactone and L-gluconolactone. J. Biol. Chem. 223 897-905.
5. Chatterjee, I. B. (1973) Evolution and the biosynthesis of ascorbic acid. Science 182, 1271-1272.
6. Pettigrew, J. D. (1986) Flying primates? megabats have the advanced pathway from eye to midbrain. Science 231, 1304-1305.
7. Thewissen, J. G. M. and Babcock, S. K. (1991) Distinctive cranial and cervical innervation of wing muscles: new evidence for bat monophyly. Science 251, 934-936.
8. Pettigrew, J. D. (1991) Wings or brains? Convergent evolution in the origin of bats. Syst. Zool. 40(2), 199-216.
9. Baker, R. T., Novacek, M. J., and Simons, N. B. (1991) On the monophyly of bats. Syst. Zool. 40(2), 216-231.
10. Pettigrew, J. D. (1991) A fruitful, wrong hypothesis? Response to Baker, Novacek, and Simmons. Syst. Zool. 40(2), 231-239.
11. Baker, R. T., Novacek, M. J., and Simons, N. B. (1991) Approaches, methods, and the future of the Chiropteran monophyly controversy: A reply to J. D. Pettigrew. Syst. Zool. 40(2), 239-243.
12. Kleinschmidt, T., Koop, B. and Braunitzer, G. (1986) The primary structure of a mouse-eared bat (Myotis velifer, Chiroptera) hemoglobin. Biol. Chem. Hoppe-Seyler 367, 1243-1249.
12a. Singer, G. A., Kleinschmidt, T., Pettigrew, J. D., Braunitzer, G. (1991) The primary structure of the hemoglobin from the Australian ghost bat (Macroderma gigas, Microchiroptera). Biol Chem Hoppe Seyler 372(12):1089-95.
12b.  Kleinschmidt, T., Sgouros, J. G., Pettigrew, J. D., and Braunitzer, G. (1988)  The primary structure of the hemoglobin from the grey-headed flying fox (Pteropus poliocephalus) and the black flying fox (P. alecto, Megachiroptera). Biol Chem Hoppe Seyler 369(9):975-84.

Go to:    Page 2: Using Hemoglobin to Track Blood Lines
           Page 3: Reliability of Molecular Phylogenies

Return to Department's Home Page, CHEM-667 Home Page, or Hal White's Home Page,
Created 7/17/00. Last updated 21 January 2013 by Hal White
Copyright 2013, Harold B. White, Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716