Factors behind past lemur species extinctions put surviving speciesin ‘ecological retreat’

Instead, in University of Cincinnati-led research on lemurextinctions over the past 2,000 years, findings suggest that onelikely result of changes that lead to species’ extinctions is thatremaining species go into “ecological retreat.” And thatretreat can result in new selective and ecological pressures thatthen increase the extinction risk of surviving species, potentiallycreating an “extinction cascade.” These conclusions are found in the Proceedings of the Royal Society B, in an article titled “Extinction and Ecological Retreat in aCommunity of Primates” by lead author Brooke Crowley,assistant professor of anthropology and geology at UC. Co-authors are Laurie Godfrey, professor of anthropology at theUniversity of Massachusetts at Amherst; Thomas Guilderson, researchscientist, and Paula Zermeno, scientific associate, both of theLawrence Livermore National Laboratory; Paul Koch, professor ofearth & planetary sciences at the University of California atSanta Cruz, and Nathaniel Dominy, associate professor ofanthropology at Dartmouth College. Using radiocarbon and isotope analysis from fossils of eightlarge-bodied lemur species that have died out in Madagascar sincethe arrival of humans to the island 2,000 years ago, the researchteam was able to determine the type of habitat in which lemurs inthe past lived, their diets, when they died out and whether otherstill-extant species filled vacated environmental niches. Findings show that prior to extensive human disturbance, lemurswere very common in open habitats of wooded savannah and spinythicket on Madagascar, which constitutes the majority ofsouthwestern Madagascar today. Replace iPhone LCD Screen

But after the larger-sized lemurs that once inhabited those regionswent extinct, related species — that existed then and are stillextant today — could not fill the empty niches. Instead,still-extant lemur species have shown, over time, an increasingreliance on habitats with dense forest cover. Said UC’s Crowley, “The reasons behind the increased relianceon densely forested habitats are uncertain, but it’s likely thatlow hunting and logging pressures in forest reserves arecontributing factors.” She added that while forested areas have experienced humandisturbance, even greater disturbance has been documented in theunprotected open, drier areas where lemur species once flourishedbut have gone extinct. According to UMass’ Godfrey, it’s not that lemur species of thepast two millennia did not live in forested areas at all nor thattoday’s species live only in forested areas. China TFT LCD Screens

Rather, lemur specieswere once very common in other, drier and more open habitats inMadagascar and so, species were not so heavily reliant on foresthabitat as they are today. Added UC’s Crowley, “It’s been assumed that lemurs were in theforests because that’s where the resources that best suited themwere. Our fossil analysis shows that lemur species once preferred amuch wider, more distinctive habitat range, which may mean thatmodern lemurs prefer the densely forested areas simply becausethese areas offer greater protection. The forest is more of arefuge.” If so, this could help explain other researchers’ previouslyreported findings regarding “mismatches” between lemuranatomy and observed behavior of modern lemurs in the dense forestenvironments. Blackberry LCD Screens Manufacturer

And such mismatches could be indications that today’s lemurs are inecological retreat and at risk if conservation and environmentalmanagement efforts don’t take into account what were once, and maylikely still be, their preferred habitats. “In other words,” explained Crowley, “We now havelong-term historical data, a broadened historical perspectiveindicating that what lemurs are doing today — preferring denselyforested areas — is not representative of their ecological nicheover past millennia. That’s an indication that we need to rethinkour assumptions on their current habitat choices and on our ownconservation efforts. And this form of historically informedresearch can also be applied to other locales and animals tobenefit threatened species.” This research was funded by the David and Lucille PackardFoundation and the University of California Laboratory Fee ResearchProgramme, with additional support from D.A. Burney, University ofCalifornia.

Significant laboratory work for this research wasconducted at the University of California-Santa Cruz and LawrenceLivermore National Laboratory.


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