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Lemur
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Lemurs make up the infraorder Lemuriformes and are members of a group of primates known as prosimians. 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 four lemuriform families, but it is also the genus of one of the lemuriform species, the Ring-tailed Lemur (Lemur catta).
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Lemurs make up the infraorder Lemuriformes and are members of a group of primates known as prosimians. 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 four 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, that are also called colugos, are not lemurs or even primates.
Classification
As shown here, the four families of lemurs are split into two superfamilies, containing 99 species and subspecies. The Cheirogaleidae have a pedal structure similar to the other strepsirrhine families and the haplorrhines, suggesting they split off from the other lemurs first. As such, the Cheirogaleoidea are a sister clade to the Lemuroidea.
Physical characteristics
Lemurs are primates found naturally only on the island of Madagascar and some smaller surrounding islands, including the Comoros (where they were likely introduced by humans). Fossil evidence indicates that they reached Madagascar after it broke away from mainland Africa, possibly by "rafting" across the ocean on large clumps of vegetation. While their ancestors were displaced in the rest of the world by monkeys, apes, and other primates, 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. The larger species, some of which weighed up to 240 kg, have all become extinct since humans settled on Madagascar, and since the early 20th century the largest lemurs reach about 10 kilograms (22 lbs). 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 causes their eyes to shine at night. Lemurs are thought to have limited color vision. Lemurs depend heavily on the sense of smell and have large nasal cavities and moist noses.
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 spends most of its time on the ground.
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."
Female dominance
Female dominance is a very rare social structure in mammals, and it is only observed consistently in hyenas and lemurs. It occurs when all adult males exhibit submissive behavior to adult females in social settings. These social settings are usually related to feeding, grooming, and sleeping site priority. Interestingly, most lemurs do not exhibit sexual dimorphism, but it remains unclear what role size and strength play in male deference.
Female social dominance was first observed in the Ring-tailed Lemur (Lemur catta). 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).
Hypotheses for the evolution of female dominance
There are three basic proposals for the evolution of female dominance:
- The Energy Conservation Hypothesis: males subordinate to females to conserve energy for the intense male-male competition experienced during lemur's very short breeding season
- Male behavioral strategy: males defer as a parental investment because it ensures more resources in the harsh unpredictable climate of Madagascar for the female, and thus, the male's future offspring.
- Female behavioral strategy: dominance helps females deal with the unusually high reproductive demands; they prevail in more social conflicts because they have more at stake in terms of fitness.
Since these original proposals, scientists like Peter Kappeler have modified and integrated other ideas, but there is no single hypothesis that can fully explain female social dominance in lemurs at this time and all three are likely to play a role.
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. There are 85 living lemur species accounted for in current publications,, with more documentation currently awaiting publication.
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. For example, the natives of Madagascar use a technique known as "slash and burn" to eliminate their previous year's crops. This, however, destroys the habitat of the lemurs and other animals in Madagascar. Idea Wild helps natives find other ways to restore their crops without using such volatile methods.
In popular culture
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 called Zoboomafoo.
- 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.
External links
- Lots of photographs, information, and research programs.
- , about 10 different lemur species living in complete freedom!
- , Site created by the Wildlife Conservation Society that provides lemur videos, photos and educational tools for teachers and parents.
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