Megabat

Megabats (fruit bats)
Temporal range: Oligocene–Recent
Large flying fox, Pteropus vampyrus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Suborder: Megachiroptera or Yinpterochiroptera
Dobson, 1875
Family: Pteropodidae
Gray, 1821
Subfamilies

Nyctimeninae
Cynopterinae
Harpiyonycterinae
Macroglossinae
Pteropodinae
Rousettinae
Epomophorinae

Megabats constitute the suborder Megachiroptera, and its only family Pteropodidae of the order Chiroptera (bats). They are also called fruit bats, Old World fruit bats,[1] or, especially the genera Acerodon and Pteropus, flying foxes. Old World fruit bats are not found in the Americas, Western Europe,[2] northwest Africa and southwest Australia.[3][4] Compared to insectivorous bats, fruit bats are relatively large and, with some exceptions, do not navigate by echolocation. They are herbivores and rely on their keen senses of sight and smell to locate food.[5]

Description

Spectacled flying fox (Pteropus conspicillatus)

Most fruit bats are larger than insectivorous bats or Microchiroptera, however there are a number of small fruit bats also. The smallest species is 6 cm (2.4 in) long and thus smaller than some microbats, for example, the Mauritian tomb bat.[6] The largest attain a wingspan of 1.7 m (5.6 ft), and weigh as much as 1.6 kg (3.5 lb).[7] Most fruit bats have large eyes, allowing them to orient themselves visually in twilight and inside caves and forests.

Their sense of smell is excellent. In contrast to the microbats, the fruit bats do not use echolocation (with one exception, the Egyptian fruit bat Rousettus egyptiacus, which uses high-pitched tongue clicks to navigate in caves).[8]

Loss of echolocation

Megabats make up the only family (Pteropodidae) in order Chiroptera that is not capable of laryngeal echolocation. Echolocation and flight evolved early in the lineage of chiropterans. Although echolocation was later lost in family Pteropodidae,[9] bats in the genus Rousettus are capable of primitive echolocation through clicking their tongue,[10] and some species have been shown to create clicks similar to those of echolocating bats using their wings.[11][12]

Both echolocation and flight are energetically expensive processes for bats.[13] The nature of the flight and echolocation mechanism of bats allows for creation of echolocation pulses with minimal energy use.[14] Energetic coupling of these two processes is thought to have allowed for both energetically expensive processes to evolve in bats. The loss of echolocation may be due to the uncoupling of flight and echolocation in megabats.[15] The larger average body size of megabats compared to echolocating bats[16] suggests that a larger body size disrupts the flight-echolocation coupling and made echolocation too energetically expensive to be conserved in megabats.[15]

Behavior and ecology

Megabats mostly roost in trees and shrubs. Only those that possess echolocation venture into the dark recesses of caves. Because they eat fruit, some megabat species are unpopular with orchard owners. Megabats are frugivorous or nectarivorous, i.e., they eat fruits or lick nectar from flowers. Often, the fruits are crushed and only the juices are consumed. The teeth are adapted to bite through hard fruit skins.

Frugivorous bats aid the distribution of plants (and therefore forests) by carrying the fruits with them and spitting the seeds or eliminating them elsewhere. Nectarivores actually pollinate visited plants. They bear long tongues that are inserted deep into the flower; pollen passed to the bat is then transported to the next blossom visited, thereby pollinating it. This relationship between plants and bats is a form of mutualism known as "chiropterophily". Examples of plants that benefit from this arrangement include the baobabs of the genus Adansonia and the sausage tree (Kigelia).

As disease reservoirs

Fruit bats have been found to act as reservoirs for ebola virus,[17] though the bats themselves sometimes have no signs of infection. Three species of bats have tested positive for ebola, but had no symptoms of the virus.[17] This indicates that the bats may be acting as a reservoir for the virus. Of the infected animals identified during these field collections, immunoglobulin G (IgG) specific for ebola virus was detected in hammer-headed bats, Franquet's epauletted fruit bats, and little collared fruit bats.

The epidemical Marburg virus was found in 2007 in specimens of the Egyptian fruit bat, confirming the suspicion that this species may be a reservoir for this virus.[18]

Other viral diseases which can be carried by fruit bats include Australian bat lyssavirus and henipavirus (notably Hendra virus and Nipah virus), both of which can prove fatal to humans. These bats have been shown to infect other species (specifically horses) with Hendra virus in Australian regions. Later, humans became infected with Hendra virus after being exposed to horse bodily fluids and excretions.[19]

Fruit bats are considered a delicacy by South Pacific Islanders, as well as in Micronesia. Consumption has been suggested as a cause of Lytico-Bodig disease on the Micronesian island of Guam, through bioaccumulation of a plant toxin to which the bats are immune.[20]

Classification

Head of a masked flying fox or fruit bat (Pteropus personatus)
Livingstone's fruit bat Pteropus livingstonii
Fox Island, Australia, is believed to be home to the largest colony of flying foxes on the continent.

Bats have been traditionally thought to belong to one of two monophyletic groups, a view that is reflected in their classification into two suborders (Megachiroptera and Microchiroptera). According to this hypothesis, all living megabats and microbats are descendants of a common ancestor species that was already capable of flight.

However, other views have been shared, and a vigorous debate persists to this date. For example, in the 1980s and 1990s, some researchers proposed (based primarily on the similarity of the visual pathways) that the Megachiroptera were in fact more closely affiliated with the primates than the Microchiroptera, with the two groups of bats having therefore evolved flight via convergence (see Flying primates theory).[21] However, a recent flurry of genetic studies confirms the more longstanding notion that all bats are indeed members of the same clade, the Chiroptera.[22][23] Other studies have recently suggested that certain families of microbats (possibly the horseshoe bats, mouse-tailed bats, and the false vampires) are evolutionarily closer to the fruit bats than to other microbats.[22][24]

List of species

The family Pteropodidae is divided into seven subfamilies with 186 total extant species, represented by 44–46 genera:

Family Pteropodidae

References

  1. ↑ Mickleburgh, Hutson and Racey. "Old World Fruit Bats: Introduction". International Union for Conservation of Nature. Retrieved July 19, 2013.
  2. ↑ BatLife Europe http://www.batlife-europe.info/about-batlife-europe/european-bats/. Retrieved 24 April 2017. Missing or empty |title= (help)
  3. ↑ Luzynski, Kenneth Cody; Sluzas, Emily Margaret; Wallen, Megan Marie. "Pteropodidae: Old World fruit bats". Animal Diversity Web/University of Michigan.
  4. ↑ Smith, Charles H. "PTEROPODIDAE (Fruit Bats/Flying Foxes)". MAMMFAUN. Western Kentucky University. (includes range map)
  5. ↑ Neuweiler, Gerhard (2000). The Biology of Bats. Oxford University Press. ISBN 978-0-19-509950-8. Retrieved 28 March 2015.
  6. ↑ Garbutt, Nick (2007). "Mauritian Tomb Bat". Mammals of Madagascar: A Complete Guide. Yale University Press. p. 67. ISBN 978-0-300-12550-4.
  7. ↑ Nowak, R.M. (1999). "Walker's Mammals of the World" (6 ed.). pp. 264–271. ISBN 0-8018-5789-9.
  8. ↑ Airas, Matti. "Echolocation in bats" (PDF). Laboratory of Acoustics and Audio Signal Processing, São Paulo State University. p. 4. Retrieved July 19, 2013.
  9. ↑ Springer, M.S.; Teeling, E.C.; Madsen, O.; Stanhope, M.J.; de Jong, W.W. (2001). "Integrated fossil and molecular data reconstruct bat echolocation". Proceedings of the National Academy of Sciences. 98 (11): 6241–6246. Bibcode:2001PNAS...98.6241S. PMC 33452 Freely accessible. PMID 11353869. doi:10.1073/pnas.111551998.
  10. ↑ Holland*, Richard A.; Waters, Dean A.; Rayner, Jeremy M. V. "Echolocation signal structure in the Megachiropteran bat Rousettus aegyptiacus Geoffroy 1810". J Exp Biol. 207: 4361–69. PMID 15557022. doi:10.1242/jeb.01288.
  11. ↑ Boonman, A; Bumrungsri, S; Yovel, Y (2014). "Nonecholocating fruit bats produce biosonar clicks with their wings". Current Biology. 24 (24): 2962–2967. PMID 25484290. doi:10.1016/j.cub.2014.10.077.
  12. ↑ Ravindran, Sandeep (4 December 2014). "When It Comes to Echolocation, Some Bats Just Wing It". National Geographic.
  13. ↑ Speakman, J.R.; Racey, P.A. (1991). "No cost of echolocation for bats in flight". Nature. 350 (6317): 421–423. Bibcode:1991Natur.350..421S. PMID 2011191. doi:10.1038/350421a0.
  14. ↑ Lancaster, W.C.; Henson, O.W.; Keating, A.W. (1995). "Respiratory muscle activity in relation to vocalization in flying bats". Journal of Experimental Biology. 198 (Pt 1): 175–191. PMID 7891034.
  15. 1 2 Altringham, J.D. (2011). Echolocation and other senses. New York: Oxford University Press.
  16. ↑ Hutcheon, J.M.; Garland, T.J. (1995). "Are megabats big?". Journal of Mammalian Evolution. 11 (3/4): 257–277. doi:10.1023/B:JOMM.0000047340.25620.89.
  17. 1 2 National Geographic, October 2007. "Deadly Contact," David Quammen, pp. 78–105.
  18. ↑ "Deadly Marburg virus discovered in fruit bats". msnbc. August 21, 2007. Retrieved 2008-03-11.
  19. ↑ "Hendra Virus Disease & Nipah Virus Encephalitis Fact Sheet" (PDF). CDC. Retrieved 2014-02-20.
  20. ↑ Monson, C. S.; Banack, S. A.; Cox, P. A. (2003). "Conservation implications of Chamorro consumption of flying foxes as a possible cause of amyotrophic lateral sclerosis-parkinsonism dementia complex in Guam". Conservation Biology. 17 (3): 678–686. doi:10.1046/j.1523-1739.2003.02049.x.
  21. ↑ Pettigrew JD, Jamieson BG, Robson SK, Hall LS, McAnally KI, Cooper HM (1989). "Phylogenetic relations between microbats, megabats and primates (Mammalia: Chiroptera and Primates)". Philosophical Transactions of the Royal Society B. 325 (1229): 489–559. Bibcode:1989RSPTB.325..489P. doi:10.1098/rstb.1989.0102.
  22. 1 2 Eick, GN; Jacobs, DS; Matthee, CA (September 2005). "A nuclear DNA phylogenetic perspective on the evolution of echolocation and historical biogeography of extant bats (chiroptera)". Molecular Biology and Evolution. 22 (9): 1869–86. PMID 15930153. doi:10.1093/molbev/msi180. Archived from the original (Free full text) on 2009-02-13.
  23. ↑ Simmons, NB; Seymour, KL; Habersetzer, J; Gunnell, GF (2008-02-14). "Primitive Early Eocene bat from Wyoming and the evolution of flight and echolocation". Nature. 451 (7180): 818–21. Bibcode:2008Natur.451..818S. PMID 18270539. doi:10.1038/nature06549. recent studies unambiguously support bat monophyly
  24. ↑ Adkins RM, Honeycutt RL (1991). "Molecular phylogeny of the superorder Archonta" (PDF). Proceedings of the National Academy of Sciences. 88 (22): 10317–10321. Bibcode:1991PNAS...8810317A. PMC 52919 Freely accessible. PMID 1658802. doi:10.1073/pnas.88.22.10317.

Further reading

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