.gif)
Lek (animal behaviour)
Encyclopedia
A lek is a gathering of male
s, of certain animal species, for the purposes of competitive mating
display. Leks assemble before and during the breeding season, on a daily basis. The same group of males meet at a traditional place and take up the same individual positions on an arena, each occupying and defending a small territory or court. Intermittently or continuously, they spar individually with their neighbors or put on extravagant visual or aural displays (mating "dances" or gymnastics, plumage displays, vocal challenges, etc.).
The term derives from the Swedish lek
, a noun which typically denotes pleasurable and less rule-bound games and activities ("play", as by children). Specifically, the etymology
of the word "lek" is from 1871 and means to engage in courtship displays (of certain animals); probably from the Swedish att leka "to play". A strict hierarchy accords the most desirable top-ranking males the most prestigious central territory, with ungraded and lesser aspirants ranged outside. Females come to these arenas to choose mates when the males' hierarchy has become established, and preferentially mate with the dominants in the centre.
, a type of fish, the males build sand castles. The lek member with the tallest mound of sand – almost a meter wide at the base – wins the females. These sandcastles take this ten centimeter (four inch) long animal two weeks to build. Peacocks also form leks to display their tails.
In a classical lek there is no male parental care, with males aggregating at the leks site where the only resource for females are the males from which they select their mate. In exploded leks, some of these may not hold and males may not aggregate in a small area but hold larger territories within which the females may also be able to forage for food.
Exploded leks rely on vocal signals. Male hammer-headed bat
s have a voice box that occupies more than half their body cavities; during breeding season, they gather for several hours at dawn and dusk to honk for females. A famous example of exploded leks is the "booming" call of the Kakapo
, the males of which position themselves many kilometers apart from one another to signal to potential mates.
In some species, the males at the leks show a high-degree of relatedness, but this does not appear to be a trend across species.
A lek when females come together to compete for males is called a mung (as in the yellow-spotted millipede).
Zahavi declared that male sexual characteristics only convey useful information to the females if these traits confer a handicap on the male. Otherwise, males could simply cheat: if the courtship displays have a neutral effect on survival, males could all perform equally and it would signify nothing to the females. But if the courtship display is somehow deleterious to the male’s survival—such as increased predator risk or time and energy expenditure—it becomes a test by which females can assess male quality. Under the “handicap principle,” males who excel at the courtship displays prove that they are of better quality and genotype, as they have already withstood the costs to having these traits.
Persistent female choice for particular male trait
values should erode genetic variance in male traits and thereby remove the benefits of choice, yet choice persists. The enigma of how additive genetic variation is maintained in the face of consistent female preference is named the “lek paradox.” This paradox can be somewhat alleviated by the occurrence of mutation
s introducing potential differences, as well as the possibility that traits of interest have more or less favorable recessive alleles.
One potential resolution to the lek paradox is Rowe and Houle’s theory of condition-dependent expression of male sexually selected traits. Similar to the handicap principle, Rowe and Houle argue that sexually selected traits depend on physical condition. Condition, in turn, summarizes a large number of genetic loci, including those involved in metabolism, muscular mass, nutrition, etc. Rowe and Houle claim that condition dependence maintains genetic variation in the face of persistent female choice, as the male trait is correlated with abundant genetic variation in condition . This is also called the "Genic Capture" hypothesis.
Genetic variation in condition-dependent traits may be further maintained through mutations and environmental effects. Genotypes may be more effective in developing condition dependent sexual characteristics in different environments, while mutations may be deleterious in one environment and advantageous in another. Thus genetic variance remains in populations through gene flow across environments or generation overlap.
In an alternate but non-exclusionary hypothesis, Hamilton and Zuk proposed that successful development of sexually selected traits signal resistance to parasites. Parasites can significantly stress their hosts so that they are unable to develop sexually selected traits as well as healthy males. According to this theory, a male who vigorously displays demonstrates that he has parasite resistant genes to the females. In support of this theory, Hamilton and Zuk found that male sexual ornaments were significantly correlated with levels of incidence of six blood diseases in North American passerine bird species. The Hamilton and Zuk model addresses the lek paradox, arguing that the cycles of co-adaptation between host and parasite resist a stable equilibrium point. Hosts continue to evolve resistance to parasites and parasites continue to bypass resistant mechanisms, continuously generating genetic variation. The genic capture and parasite resistance hypotheses could logically co-occur in the same population.
(orrlek) and for Capercaillie
(tjäderlek), and lekking behaviour is quite common in bird
s of this type, such as Sage Grouse
, Prairie Chicken
, and Sharp-tailed Grouse
. However it is also shown by birds of other families, such as the Ruff, Great Snipe
, Musk Duck
s, Hermit hummingbirds
, Manakin
s, birds of paradise, Screaming Pihas and the Kakapo
, by some mammals such as the Ugandan Kob
(a waterbuck
), several species of fruit bat
and the topi
, and by some species of fish
and even insects like the midge
and the Ghost Moth
. The rut
of deer
is also very similar. There is some dispute among ethologists
as to whether the lekking behaviour shown by animals of widely different groups should really be treated as the same, and in particular whether similar selective pressures have led to their emergence.
In a few species (peacocks and the black grouse), leks are composed of brothers and half-brothers. The lower-ranking males gain some fitness benefit by passing their genes on through attracting mates for their brothers (larger leks attract more females). Peacocks recognize and will lek with their brothers, even if they have never met before.
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s, of certain animal species, for the purposes of competitive mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
display. Leks assemble before and during the breeding season, on a daily basis. The same group of males meet at a traditional place and take up the same individual positions on an arena, each occupying and defending a small territory or court. Intermittently or continuously, they spar individually with their neighbors or put on extravagant visual or aural displays (mating "dances" or gymnastics, plumage displays, vocal challenges, etc.).
-lock
The suffix -lock in Modern English survives only in wedlock. It descends from Old English -lác which was more productive, carrying a meaning of "action or proceeding, state of being, practice, ritual". As a noun, Old English lác means "play, sport", deriving from an earlier meaning of "sacrificial...
, a noun which typically denotes pleasurable and less rule-bound games and activities ("play", as by children). Specifically, the etymology
Etymology
Etymology is the study of the history of words, their origins, and how their form and meaning have changed over time.For languages with a long written history, etymologists make use of texts in these languages and texts about the languages to gather knowledge about how words were used during...
of the word "lek" is from 1871 and means to engage in courtship displays (of certain animals); probably from the Swedish att leka "to play". A strict hierarchy accords the most desirable top-ranking males the most prestigious central territory, with ungraded and lesser aspirants ranged outside. Females come to these arenas to choose mates when the males' hierarchy has become established, and preferentially mate with the dominants in the centre.
Lekking behavior
Two main types of lek are distinguished, classical leks and exploded leks. In classical leks, individuals gather within sight of each other to court and compete. Physical contest in these situations is frequent, and plays a major role in the mating rituals of certain shorebird and gamebird species. In Copadichromis eucinostomusCopadichromis eucinostomus
Copadichromis eucinostomus is a species of fish in the Cichlidae family. It is found in Malawi, Mozambique, and Tanzania. Its natural habitat is freshwater lakes....
, a type of fish, the males build sand castles. The lek member with the tallest mound of sand – almost a meter wide at the base – wins the females. These sandcastles take this ten centimeter (four inch) long animal two weeks to build. Peacocks also form leks to display their tails.
In a classical lek there is no male parental care, with males aggregating at the leks site where the only resource for females are the males from which they select their mate. In exploded leks, some of these may not hold and males may not aggregate in a small area but hold larger territories within which the females may also be able to forage for food.
Exploded leks rely on vocal signals. Male hammer-headed bat
Hammer-headed bat
The Hammer-headed Bat , also known as the Big-lipped Bat, is a megabat widely distributed in equatorial Africa. This large bat is found in riverine forests, mangroves, swamps, and palm forests at elevations less than 1800 meters.- Taxonomy :The hammer-headed bat is a member of the family Pteropodidae...
s have a voice box that occupies more than half their body cavities; during breeding season, they gather for several hours at dawn and dusk to honk for females. A famous example of exploded leks is the "booming" call of the Kakapo
Kakapo
The Kakapo , Strigops habroptila , also called owl parrot, is a species of large, flightless nocturnal parrot endemic to New Zealand...
, the males of which position themselves many kilometers apart from one another to signal to potential mates.
In some species, the males at the leks show a high-degree of relatedness, but this does not appear to be a trend across species.
A lek when females come together to compete for males is called a mung (as in the yellow-spotted millipede).
The lek paradox
In a lekking reproductive system, what male sexual characteristics can signal to females is limited, as the males provide no resources to females or parental care to their offspring. This implies that females gain indirect benefits from her choice in the form of “good genes” for her offspring. Hypothetically, in choosing a male who excels at courtship displays, females will gain genes for her offspring that will increase their survival or reproductive fitness.Zahavi declared that male sexual characteristics only convey useful information to the females if these traits confer a handicap on the male. Otherwise, males could simply cheat: if the courtship displays have a neutral effect on survival, males could all perform equally and it would signify nothing to the females. But if the courtship display is somehow deleterious to the male’s survival—such as increased predator risk or time and energy expenditure—it becomes a test by which females can assess male quality. Under the “handicap principle,” males who excel at the courtship displays prove that they are of better quality and genotype, as they have already withstood the costs to having these traits.
Trait (biology)
A trait is a distinct variant of a phenotypic character of an organism that may be inherited, environmentally determined or be a combination of the two...
values should erode genetic variance in male traits and thereby remove the benefits of choice, yet choice persists. The enigma of how additive genetic variation is maintained in the face of consistent female preference is named the “lek paradox.” This paradox can be somewhat alleviated by the occurrence of mutation
Mutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
s introducing potential differences, as well as the possibility that traits of interest have more or less favorable recessive alleles.
One potential resolution to the lek paradox is Rowe and Houle’s theory of condition-dependent expression of male sexually selected traits. Similar to the handicap principle, Rowe and Houle argue that sexually selected traits depend on physical condition. Condition, in turn, summarizes a large number of genetic loci, including those involved in metabolism, muscular mass, nutrition, etc. Rowe and Houle claim that condition dependence maintains genetic variation in the face of persistent female choice, as the male trait is correlated with abundant genetic variation in condition . This is also called the "Genic Capture" hypothesis.
Genetic variation in condition-dependent traits may be further maintained through mutations and environmental effects. Genotypes may be more effective in developing condition dependent sexual characteristics in different environments, while mutations may be deleterious in one environment and advantageous in another. Thus genetic variance remains in populations through gene flow across environments or generation overlap.
Lekking species
The term was originally used most commonly for Black GrouseBlack Grouse
The Black Grouse or Blackgame is a large bird in the grouse family. It is a sedentary species, breeding across northern Eurasia in moorland and bog areas near to woodland, mostly boreal...
(orrlek) and for Capercaillie
Capercaillie
The Western Capercaillie , also known as the Wood Grouse, Heather Cock or Capercaillie , is the largest member of the grouse family, reaching over 100 cm in length and 6.7 kg in weight. The largest one ever recorded in captivity had a weight of 7.2 kg....
(tjäderlek), and lekking behaviour is quite common in bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s of this type, such as Sage Grouse
Sage Grouse
The Sage Grouse is the largest grouse in North America, where it is known as the Greater Sage-Grouse. Its range is sagebrush country in the western United States and southern Alberta and Saskatchewan, Canada. A population of smaller birds, known in the U.S. as Gunnison Sage-Grouse, were recently...
, Prairie Chicken
Prairie Chicken
Prairie Chicken refers to several birds in the genus Tympanuchus:*Greater Prairie Chicken **Attwater's Prairie Chicken **Heath Hen **Tympanuchus cupido pinnatus...
, and Sharp-tailed Grouse
Sharp-tailed Grouse
The Sharp-tailed Grouse, Tympanuchus phasianellus , is a medium-sized prairie grouse. It is also known as the sharptail, and is known as "fire grouse" or "fire bird" by Native American Indians due to their reliance on brush fires to keep their habitat open.-Taxonomy:The Greater Prairie-chicken,...
. However it is also shown by birds of other families, such as the Ruff, Great Snipe
Great Snipe
The Great Snipe, Gallinago media is a small stocky wader in the genus Gallinago.This bird's breeding habitat is marshes and wet meadows with short vegetation in north-eastern Europe including north-western Russia. Great Snipes are migratory, wintering in Africa...
, Musk Duck
Musk Duck
The Musk Duck is a highly aquatic, stiff-tailed duck native to southern Australia. It is the only living member of the genus Biziura. An extinct relative, the New Zealand Musk Duck or de Lautour's Duck , once occurred on New Zealand, but is only known from prehistoric subfossil bones...
s, Hermit hummingbirds
Green Hermit
The Green Hermit is a large hummingbird that is a resident breeder from southern Central America south to northwestern South America It is 5.3 in long and weighs 0.22 oz . The male Green Hermit is mainly dark green with a blue-green rump...
, Manakin
Manakin
The manakins are a family, Pipridae, of unique small suboscine passerine birds. The family contains some 60 species. They are distributed through the American tropics...
s, birds of paradise, Screaming Pihas and the Kakapo
Kakapo
The Kakapo , Strigops habroptila , also called owl parrot, is a species of large, flightless nocturnal parrot endemic to New Zealand...
, by some mammals such as the Ugandan Kob
Ugandan Kob
The Ugandan Kob is a subspecies of the kob, a type of antelope found in sub-Saharan Africa in Sudan, Uganda, Democratic Republic of Congo and Ethiopia. It is normally reddish-brown, in which it differs from other kob subspecies...
(a waterbuck
Reduncinae
The subfamily Reduncinae is composed 8 species of antelope all of which dwell in marshes, floodplains or other well-watered areas, including the waterbucks and reedbucks...
), several species of fruit bat
Fruit Bat
Fruit Bat can refer to:* Megabats, a species of bat which eats fruit* Les "Fruitbat" Carter, guitarist of Carter the Unstoppable Sex Machine* Fruit Bats , an American band...
and the topi
Topi
The Tsessebe , is one of five subspecies in the binomial class D. lunatus. The other subspecies include Korrigum , Tiang , Coastal Topi , and Topi . Tesessebe are found primarily in Zambia, Namibia, Botswana, Zimbabwe, and South Africa...
, and by some species of fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
and even insects like the midge
Midge (insect)
Midges comprise many kinds of very small two-winged flies found world-wide. The term does not encapsulate a well-defined taxonomic group, but includes animals in several families of Nematoceran Diptera. While some midges are vectors for disease, many others play useful roles as prey items for...
and the Ghost Moth
Ghost Moth
The Ghost Moth , also known as the Ghost Swift, is a moth of the family Hepialidae. It is common throughout Europe except for the far south-east...
. The rut
Rut (mammalian reproduction)
The rut is the mating season of ruminant animals such as deer, sheep, elk, moose, caribou, ibex, goats, pronghorn and Asian and African antelope....
of deer
Deer
Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...
is also very similar. There is some dispute among ethologists
Ethology
Ethology is the scientific study of animal behavior, and a sub-topic of zoology....
as to whether the lekking behaviour shown by animals of widely different groups should really be treated as the same, and in particular whether similar selective pressures have led to their emergence.
In a few species (peacocks and the black grouse), leks are composed of brothers and half-brothers. The lower-ranking males gain some fitness benefit by passing their genes on through attracting mates for their brothers (larger leks attract more females). Peacocks recognize and will lek with their brothers, even if they have never met before.
Further reading
- Snow, B.K. & Snow, D.W. (1979). "The Ochre-bellied FlycatcherOchre-bellied FlycatcherThe Ochre-bellied Flycatcher, Mionectes oleagineus, is a small bird of the tyrant flycatcher family. It breeds from southern Mexico through Central America, and South America east of the Andes as far as southern Brazil, and on Trinidad and Tobago....
and the Evolution of Lek Behavior." Condor 81(3)