"Long before it's in the papers"
June 03, 2013

RETURN TO THE WORLD SCIENCE HOME PAGE

Lizard builds big, close-knit family homes

May 12, 2011
Courtesy of 
and World Science staff

Dart­ing around with their beady eyes and scaly skin, liz­ard­s—like oth­er rep­tiles—rarely seem like the warm, cuddly types. 

Yet to their family mem­bers, lizards of one spe­cies might be just that. A study has found they form close-knit fam­i­lies, fea­tur­ing rel­a­tively mo­nog­a­mous par­ents and sprawl­ing tun­nel homes built and main­tained with even the young­sters’ help.

Re­search­ers Steve McAlpin, Paul Duck­ett and Ad­am Stow of Mac­quarie Un­ivers­ity in Aus­tral­ia stud­ied the lives of great des­ert bur­row­ing skinks, a threat­ened spe­cies from Cen­tral Aus­tral­ia’s sandy plains. They found that skink family mem­bers col­la­bo­rate to cre­ate and main­tain bur­row sys­tems that can have up to 20 en­trances, ex­tend over 13 me­ters (yards), and even have their own spe­cif­ic­ally lo­cat­ed la­trines. No oth­er oth­er liz­ard spe­cies, the in­ves­ti­ga­tors said, is known to co­op­er­ate to build long-term homes. 

Mate fi­del­ity, like­wise, is un­com­mon among liz­ards, but skink mates were found to breed to­geth­er over suc­ces­sive years—a lev­el of faith­ful­ness probably es­sen­tial to group co­he­sion, the re­search­ers said. But this de­vo­tion had its lim­its, with 40 per­cent of male liz­ards be­ing found to have al­so bred with dif­fer­ent fema­les.

The re­search took place at Aus­tral­ia’s Uluru-Kata Tjuta Na­t­ional Park as part of McAlpin’s Mas­ters de­gree stud­ies un­der Stow’s su­per­vi­sion. 

Up to about 10 of the brightly col­ored liz­ards, which are up to 40 cm (16 inches) long as adults, live in a bur­row, ac­cord­ing to the Aus­tral­ian Wild­life Con­serv­an­cy, based in Subi­aco, West­ern Aus­tral­ia.

The shared homes of mem­bers of the spe­cies—scientific­ally dubbed Li­o­pho­lis kin­tor­ei—can be con­tin­u­ously oc­cu­pied for up to se­ven years, ac­cord­ing to Mc­Alpin and col­leagues. Mul­ti­ple genera­t­ions par­ti­ci­pate in con­struc­tion and main­te­nance, they added; tun­nels are mostly dug and main­tained by adults, while young­sters con­trib­ute small chan­nels too nar­row for adults to work on.

DNA tests in­di­cat­ed im­ma­ture liz­ards in the same bur­row were mostly full sib­lings; par­ents were al­ways cap­tured at bur­rows con­tain­ing their off­spring. “For adults to in­vest so much in a home with­in which kids ma­ture, it makes ev­o­lu­tion­ary sense that these adult in­di­vid­u­als are sure that they are pro­vid­ing for their own off­spring,” said Stow. The in­ves­ti­ga­tors plan lat­er to look in­to the pa­ren­tal care the skink pro­vides; the ef­forts dif­fer­ent in­di­vid­u­als put in­to home­mak­ing; and how fam­i­lies may iden­ti­fy and deal with sib­lings that are skimp­ing on their share of the work.

The new find­ings were pub­lished May 11 on­line in the re­search jour­nal PLoS One.

* * *

Darting around with their beady eyes and scaly skin, lizards—like other reptiles—rarely come across as the warm, cuddly types. Yet to its family members, one species of lizard might be just that. A study has found it forms close-knit families, featuring relatively monogamous parents and sprawling tunnel homes built and maintained with even the youngsters’ help. Researchers Steve McAlpin, Paul Duckett and Adam Stow of Macquarie University in Australia studied the lives of great desert burrowing skinks, a threatened species from Central Australia’s sandy plains. They found that skink family members collaborate to create and maintain burrow systems that can have up to 20 entrances, extend over 13 meters (yards), and even have their own specifically located latrines. No other other lizard species, the investigators said, is known to cooperate to build long-term homes. Mate fidelity, likewise, is uncommon among other lizards, but skink mates were found to breed together over successive years—a level of faithfulness probably essential to group cohesion, the researchers said. But this devotion had its limits, with 40 percent of male lizards being found to have also bred with different females. The research took place at Australia’s Uluru-Kata Tjuta National Park as part of McAlpin’s Masters degree studies under Stow’s supervision. Up to about 10 of the brightly colored lizards, which are up to 40 cm (16 inches) long as adults, live in a burrow, according to the Australian Wildlife Conservancy, based in Subiaco, Western Australia. The shared homes of members of the species—scientifically dubbed Liopholis kintorei—can be continuously occupied for up to seven years, according to McAlpin’s group. Multiple generations participate in construction and maintenance, they added; tunnels are mostly dug and maintained by adults, while youngsters contribute small channels too narrow for adults to work on. DNA tests indicated immature lizards in the same burrow were mostly full siblings; parents were always captured at burrows containing their offspring. “For adults to invest so much in a home within which kids mature, it makes evolutionary sense that these adult individuals are sure that they are providing for their own offspring,” said Stow. The investigators plan later to look into the parental care the skink provides; the efforts different individuals put into homemaking; and how families may identify and deal with siblings that are skimping on their share of the work.