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Microlophus albemarlensisGalapagos Lava Lizard

By Tze Keong Chow

Geographic Range

Microlophus albemarlensis (lava lizards), along with six other related species, are found on Ecuador's Galapagos Islands. These different species are believed to have descended from a common South American ancestor. Lava lizards can be found on all major islands of the Galapagos but some species only occupy certain islands. Microlophus albemarlensis can be found on all central and western islands of the Galapagos. (Jackson, 1985)

Habitat

Microlophus albemarlensis lives in the lowland dry zones of the Galapagos Islands. Here the soil is loose and contains dry leaf litter so that the lizards are able to bury themselves in the soil at night. Rocks must also be abundant so that the lizards can hide underneath them or in crevices for protection from the sun. The habitat is also covered with flora such as cacti and vineplants, which provide shelter from the sun as well as food by attracting insects. Populations of Microlophus albemarlensis also decrease as the low, dry land gives way to forest. (Stebbins, et al., 1967)

Physical Description

Microlophus albemarlensis has primary features similar to most other species of lizards. The males have dark bodies with yellow-green markings. Females are reddish brown in color without markings. Females also have red cheek patches when they reach maturity during breeding seasons. Like most other lizards, both sexes exhibit changes in color depending on mood. Coloration also depends on where the lizards live. Those that live on dark lava are usually darker than those that live on light sandy land. Males are generally 2 to 3 times larger than females. Adult males can range from 22 - 25 cm while females range from 17 - 20 cm in length. Male dorsal scales are more heavily keeled and have longer spines. Despite the obvious sexual dimorphism, it is hard to tell the sex of young Microlophus albemarlensis because juveniles resemble females. (Jackson, 1985; Stebbins, et al., 1967)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • male more colorful
  • Range length
    17 to 25 cm
    6.69 to 9.84 in

Development

Incubation of eggs takes about 3 months after which babies hatch out of their shells 3 - 4 cm long. Males get their yellow-green markings when they reach sexual maturity. Before that, males are hard to distinguish from females. Females mature much faster than males. Upon reaching sexual maturity, females may mate successfully during the breeding season and have a clutch of their own. (Jackson, 1985)

Reproduction

During mating season, males will engage in "push up" displays to attract females. This "push up" display is also used to challenge and intimidate other males who might be wandering into its territory looking for females. When challenged, the lizard will flatten out its side, lower its throat skin and assume the "push up" display. Males will also fight using their tails and sides to slap at other competing males. Females' cheek patches will turn very red during breeding seasons as a sign to males that she is ready to mate. Male M. albemarlensis are not the most gentle of mates. They commonly seize the females by the skin, usually at the neck, and drag them over a distance before copulating. Successful males usually have a harem as their territory overlaps with 2-4 other females. However, if the female is not ready for mating, she will either escape or may even chase the male away with a charge of her own. Females also use odor to signal that they are not in the mood to be bothered. (Stebbins, et al., 1967)

Breeding season lasts from November to March. Here successful females will lay a clutch of eggs, usually 1-4, in a nest deep in the soil. Females may breed every 3 to 4 weeks during the season. The incubation peroiod of the eggs is about 3 months where young emerge about 3-4 cm in length. Males take about 3 years to reach sexual maturity while females only take 9 months. (Jackson, 1985; Prieto, et al., 1976; Stebbins, et al., 1967)

  • Breeding interval
    Every 3 -4 weeks during breeding season
  • Breeding season
    November to March
  • Range number of offspring
    1 to 4
  • Average number of offspring
    2
  • Average gestation period
    3 months
  • Average age at sexual or reproductive maturity (female)
    9 months
  • Average age at sexual or reproductive maturity (male)
    3 years

No available information was found on parental care in this species.

Lifespan/Longevity

Microlophus albemarlensis can live up to 10 years. (Jackson, 1985)

  • Range lifespan
    Status: wild
    10 (high) years

Behavior

In general, lizards appear when the sun rises (as early as 6am). Some lizards may start to forage immediately. The activity of the lizards increases by mid-morning when the ground starts to heat up rapidly. However, by mid-day, when the temperature rises beyond tolerable limits, they retreat from exposed positions to seek shelter under rocks, leaf litter or plants. (Stebbins, et al., 1967)

  • Range territory size
    129 to 378 m^2

Home Range

The average home range for male Microlophus albemarlensis is around 378 square meters. While for females its around 129 square meters. The home ranges of males usually overlaps with several females which he may court on a regular basis. Males wandering into other male or even female home ranges may be chased away. (Stebbins, et al., 1967)

Communication and Perception

These lizards do not communicate using any form of vocal communication. Most of their communication is through visual display because vision is their best-developed sense. "Push up" displays are used to ward off intruders as well as courtship communication. Change of skin color can communicate the mood of the lizard from fear to aggression. Other actions are used indicate the intentions of individuals. For example, females are known to turn their back to males, raise their tail and shake it from side to side as a sign of rejection to approaching males. It is also believed that females use odors to dissuade male lizards during breeding season. (Stebbins, et al., 1967)

Food Habits

Microlophus albemarlensis in the wild are mainly insectivores. They eat insects such as moths, flies, beetles, grasshoppers and ants. They also feed on other arthropods like spiders and centipedes. Geckos are sometimes found in the stomachs of these lizards. They eat plant material like cactus flowers if the weather is very dry and food is scarce. With man living in close proximity to these lizards, things such as bread crumbs, meat scraps and even macaroni are eaten. This makes them fairly well-rounded omnivores. (Jackson, 1985; Stebbins, et al., 1967)

  • Animal Foods
  • reptiles
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • leaves
  • seeds, grains, and nuts

Predation

Markings on lava lizards' bodies differ depending on the environment they live in, giving them a form of cryptic protection against predators. If the surroundings are dark, their markings will be darker. The same goes for light surroundings. They can also drop their tails to distract predators long enough for them to escape. They can regenerate their tails but it rarely grows back to its original length. Known predators are hawks, snakes, mocking birds, herons, rats and feral cats. (Jackson, 1985; Stebbins, et al., 1967)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Since Microlophus albemarlensis feeds mainly on a selection of insects and other arthropods, they may be important at keeping arthropod populations in check. At times, seeds are found in the stomachs of some lizards and in this way they may help disperse them through their droppings. A commensal relationship is sometimes observed when M. albemarlensis can be seen perched on the tails of Amblyrhynchus cristatus (marine iguanas) in order to eat small insects attracted to the iguanas. (Stebbins, et al., 1967)

  • Ecosystem Impact
  • disperses seeds
Species Used as Host

Economic Importance for Humans: Positive

Lava lizards are kept as pets in some homes. More importantly, they (like the finches of the Galapagos) are used to study evolution of species in the form of adaptive radiations. The 7 species of Microlophus living on the islands have descended from a single, common South American ancestor, which is believed to have floated to the Galapagos on drift-wood or other vegetation. (Stebbins, et al., 1967)

Economic Importance for Humans: Negative

There are no known adverse affects of Microlophus albemarlensis on humans.

Conservation Status

Microlophus albemarlensis was not found on the IUCN red list of endangered species database. Its conservation status is thus unknown, although one website states that a species of lava lizard on the island of Santa María (Floreana) in the Galapagos, is being threatened by black rats and feral cats. ("International Union for Conservation of Nature and Natural Resources", 2002)

Contributors

Matthew Wund (editor), University of Michigan-Ann Arbor.

Tze Keong Chow (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

fertilization

union of egg and spermatozoan

insectivore

An animal that eats mainly insects or spiders.

internal fertilization

fertilization takes place within the female's body

island endemic

animals that live only on an island or set of islands.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

International Union for Conservation of Nature. 2002. "International Union for Conservation of Nature and Natural Resources" (On-line ). The IUCN red list of Endangered Species. Accessed March 23 2003 at http://www.redlist.org.

Carpenter, C. 1977. The aggressive displays of three species of South American iguanid lizards of the genus Tropidurus. Herpetologica, 33/3: 285.

Jackson, M. H. 1985. Galapapagos: A Natural History Guide. The University of Calgary Press.

Prieto, A., J. Leon, O. Lara. 1976. Reproduction in the tropical lizard, Tropidurus hispidus. Herpetologica, 32/3: 319.

Stebbins, R., J. Lowenstein, N. Cohen. 1967. A field study of the lava lizard (Tropidurus albemarlensis) in the Galapagos Islands. Ecology, 48/5: 839.

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