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Lemur

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Lemurs[1]
Black-and-white Ruffed Lemur (Varecia variegata)
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Mammalia
Order:
Primates
Suborder:
Strepsirrhini
Infraorder:
Lemuriformes

Gray, 1821
Superfamilies and Families

Lemurs make up the infraorder Lemuriformes and are members of a group of primates known as strepsirrhines. The term "lemur" is derived from the Latin word lemures, meaning "spirits of the night" or "ghosts". This likely refers to their large, reflective eyes and the wailing cries of some species (the Indri in particular). The term is generically used for the members of the five lemuriform families, but it is also the genus of one of the lemuriform species, the Ring-tailed Lemur (Lemur catta). The two so-called flying lemur species, known formally as colugos, are not lemurs or even primates.

Classification

Main article: List of lemur species

The 4 families of lemurs are split into two superfamilies, containing 99 species and subspecies.[2] The Cheirogaleidae have a pedal structure similar to the other strepsirrhine families and the haplorrhines, suggesting they split off from the other lemurs first.[citation needed] As such, the Cheirogaleoidea are a sister clade to the Lemuroidea.

Physical characteristics

Lemurs are primates endemic to the island of Madagascar and smaller surrounding islands, such as the Comoros, where they were likely introduced by humans. Molecular genetics indicates that they reached Madagascar after it broke away from mainland Africa, possibly by "rafting" across the ocean on large clumps of vegetation.[3] While their ancestors were displaced in the rest of the world by monkeys and apes, the lemurs were safe from competition on Madagascar and differentiated into a number of species. These range in size from the tiny 30 gram (1 oz) Pygmy Mouse Lemur to the 10 kilogram (22 lb) Indri. Larger species, some of which weighed up to 240 kg[4], have all become extinct since humans settled on Madagascar. Typically, the smaller lemurs are nocturnal, while the larger ones are diurnal.

The small cheirogaleoids are generally omnivores, eating a variety of fruits, flowers and leaves (and sometimes nectar) as well as insects, spiders and small vertebrates. The remainder of the lemurs - the lemuroids - are primarily herbivores, although some species supplement their diet with insects.

Except for the Indri, all lemurs have long tails that they use for communication with each other and balance when leaping between trees. They have opposable thumbs and long toes adapted for gripping tree branches. Lemurs have nails rather than claws on all digits except the second toe of each hind foot, which has a toilet-claw for grooming. All lemur species have a tapetum, the reflective layer over the retina that enhances night vision.[4] Lemurs are thought to have limited color vision.[4] Lemurs depend heavily on the sense of smell and have large nasal cavities and moist noses.[4]

Unlike most other primates, lemur species that live in groups have a matriarchal society (i.e., females are dominant over males). Most lemur species are arboreal and traverse the canopy by vertical clinging and leaping or quadrupedalism, with the exception of the Ring-Tailed Lemur, which spend more time on the ground than other species.

Hybrids may occur between different species of lemur. In The variation of animals and plants under domestication Charles Darwin noted: "Several members of the family of Lemurs have produced hybrids in the Zoological Gardens."[5]

Female Dominance

Female (top) and male (bottom) black lemurs in their natural habitat in Madagascar. This species exhibits sexually dimorphic coat color.

Many, but not all, lemur species exhibit female dominance, which is a very rare social structure in mammals, and it is only observed consistently in hyenas and lemurs.[6] In species where this occurs, adult males exhibit submissive behavior to adult females in social settings, such as feeding, grooming, and sleeping site priority. Interestingly, most lemurs do not exhibit sexual dimorphism,[7] but it remains unclear what role size and strength play in male deference. Although several hypotheses have been proposed to explain the evolution of female dominance in the last 20 years,[8] the hypotheses have been unsatisfactory among researchers and there is currently no generally accepted hypothesis. A compelling and simple explanation, however, was recently introduced by Dunham [9] who suggested that female dominance in lemurs arises from a combination of having similar sized sexes and higher resource needs of females for reproduction. Simple game theory states that in a contest between two individuals with similar fighting capacity, the contestant with higher resource need is likely to devote more energy into fighting for that resource [10]. Species 1 will be expected to win a contest when the simple inequality: V1/K1 > V2/K2, is met, where V is the value of the resource to the contestant in terms of fitness and K is the fighting capacity measured as a rate of fitness loss. Because male and female lemurs are of the same size, the fighting capacity should not differ. Therefore a contest between a male and a female lemur will most likely be decided by who has the higher resource need. With very short reproductive seasons and lack of male care, male lemurs are assumed to expend much less energy in reproduction relative to females (i.e. pregnancy, lactation, maternal care, etc.). As such, a female has more to lose in terms of fitness by not attaining the resource and is therefore more likely to win a contest with a male. Because fighting can be costly it may be beneficial for males if they can asses their chance of winning based on sex, thus submitting to females. Evidence supporting this hypothesis is also found in birds and other mammals [11].

Female social dominance was first observed in the Ring-tailed Lemur (Lemur catta).[12] Since then, many, but not all, species of lemurs have been found to demonstrate female social dominance including the Crowned Lemur (Eulemur coronatus) and the Gray Mouse Lemur (Microcebus murinus).[citation needed]

Conservation

Most lemurs are listed as endangered or threatened species. Many species have gone extinct in the last centuries, mainly due to habitat destruction (deforestation) and hunting. Conservation of lemurs in Madagascar is a high priority, but the country's poor economic situation and the lemurs' limited range make it an uphill battle. In 2008, a total of 99 living lemur species were formally recognized,[13] with more species likely to be discovered or differentiated in the future.

One of the foremost lemur research facilities is the Duke Lemur Center. Also, Idea Wild (ideawild.org) has contributed to some projects on the conservation of different areas in Madagascar to prevent further deforestation. Idea Wild helps Malagasy farmers find more sustainable alternatives to slash and burn agriculture which destroys the habitat of the lemurs and other animals in Madagascar.

Lemurs are not as commonly seen in popular culture settings as other primates, but their popularity has grown recently due to greater exposure.

  • Lemur Street is a twenty-episode series focused on two groups of Ring-tailed Lemurs in Madagascar. Released in the United States as Animal Planet™ series Lemur Kingdom, it features rival groups fighting for land and food to survive.
  • Zoboomafoo, a show on the American television broadcasting service PBS, features a lemur of the same name.
  • Some viewed lemur fossils found in the Indian subcontinent as evidence for a lost continent called Lemuria. (Living lemurs are found only on Madagascar and nearby islands.) These claims became obsolete after the arrival of modern theories like Plate Tectonics. The concept is also associated with ancient Dravida (Tamil) country or Kumari Kandam.
  • DreamWorks Animation's Madagascar movies depict many singing, dancing lemurs, including King Julian, the "king of the lemurs."
  • JayJay the Silky Sifaka lemur from Eoin Colfer's book: Artemis Fowl: The Time Paradox. JayJay is the last surviving Silky Sifaka lemur and can cure the fairy disease of Spelltropy in this fictional adventure.
  • Ben Savage has a pet lemur named Mukman or "Mucky" for short.

References

  1. ^ a b Groves, C. P. (2005). Wilson, D. E.; Reeder, D. M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 111–121. ISBN 0-801-88221-4. OCLC 62265494.
  2. ^ Mittermeier, R. A.; et al. (2008). "Lemur Diversity in Madagascar". International Journal of Primatology. 29: 1607–1656. doi:10.1007/s10764-008-9317-y. {{cite journal}}: Explicit use of et al. in: |author= (help)
  3. ^ Mittermeier, R.A. (2006). Lemurs of Madagascar (2nd ed.). Conservation International. p. 104–107. ISBN 1-881173-88-7. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. ^ a b c d Strier, Karen B. (2000). Primate Behavioral Ecology. Boston: Allyn and Bacon. p. 49.
  5. ^ Darwin, C. (1868). The variation of animals and plants under domestication. Vol. 2 (1st ed.). London: John Murray. p. 153. ISBN 1421270730.
  6. ^ Digby, LI and Kahlenberg, SM (2002). "Female dominance in blue-eyed black lemurs". Primates. 43: 191–199. doi:10.1007/BF02629647.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Engelhardt, NV, Kappeler, PM, and Heistermann, M (2000). "Androgen levels and female social dominance in Lemur catta". Proc. R. Soc. Lond. B. 267: 1539–1553.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  8. ^ Young, AL, Richard, AF, and Aiello, LC (1990). "Female Dominance and Maternal Invesment in Strepsirhine Primates". The American Naturalist. 135: 473–488. doi:10.1086/285057.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ Dunham, AE (2008). "Battle of the sexes: Cost asymmetry explains female dominance in lemurs". Animal Behavior. 76: 1435–1439. doi:10.1016/j.anbehav.2008.06.018.
  10. ^ Parker, GA, and Rubenstein, DI (1981). "Role assessment reserve strategy, and acquisition of information in asymmetric animal contests". Animal Behaviour. 26: 221–240.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Dunham, AE (2008). "Battle of the sexes: Cost asymmetry explains female dominance in lemurs". Animal Behavior. 76: 1435–1439. doi:10.1016/j.anbehav.2008.06.018.
  12. ^ Jolly, A (1966). Lemur Behavior. Chicago: University of Chicago Press.
  13. ^ Mittermeier, R., Ganzhorn, J., Konstant, W., Glander, K., Tattersall, I., Groves, C., Rylands, A., Hapke, A., Ratsimbazafy, J., Mayor, M., Louis, E., Rumpler, Y., Schwitzer, C. & Rasoloarison, R. (December 2008). "Lemur Diversity in Madagascar". International Journal of Primatology. 29 (6): 1607–1656. doi:10.1007/s10764-008-9317-y.{{cite journal}}: CS1 maint: date and year (link) CS1 maint: multiple names: authors list (link)

See also

Ida (fossil)

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