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The colossal hats (pukao) of monumental statues: an analysis of shape variability among the pukao or Rapa Nui - Sean Hixon

You’re invited to join us on Thursday March 21 from 12-2pm at the IOMRC Auditorium for a unique seminar series from visiting father and son scholars in marine ecology and archaeology, Professor Mark Hixon and Sean Hixon. Mark joins us from the University of Hawai‘i, where he is Sidney and Erica Hsiao Endowed Professor of Marine Biology and will be talking about metapopulation dynamics in coral reef fishes. Sean is a paleoecology PhD student at Penn State, currently studying the ANU bone collection in Canberra; he will be presenting work at Easter Island with the Rapa Nui. More information on their talks below:

Toward Metapopulation Ecology of Coral Reef Fishes - Mark Hixon

Marine metapopulations occur where local populations of sedentary adults are replenished by offspring that disperse between those populations.  Understanding metapopulation dynamics is clearly important for marine conservation (e.g., design of marine reserve networks) and management (e.g., stock boundaries and dynamics).  My lab has examined population dynamics of coral reef fishes in the Bahamas at three spatial and temporal scales in an effort to link local dynamics with processes operating at the metapopulation level:  (1) patches over weeks, which provide insight on the behavioral mechanisms of local demographic density dependence; (2) reefs over years, which provide evidence of whether or not local density dependence scales-up to reef-scale population regulation; and (3) islands over years (and beyond), which provide the relationship between local demography and larval dispersal, what we call “demographic connectivity.”  We have found that (1) predation, often interacting with competition, is a common mechanism of local density dependence; (2) local density dependence does indeed result in population regulation at the reef scale; and (3) only by integrating measures of local larval production with genetic measures of larval dispersal could we accurately estimate the level of demographically meaningful connectivity that allows the regional metapopulation to persist.

MARK HIXON is the Sidney and Erica Hsiao Endowed Professor of Marine Biology at the University of Hawai‘i.  He studies the ecology and conservation biology of coral reefs, especially involving fishes, focusing on enhancing ecological resilience against ocean warming and invasive species.  Mark was honored in 2004 by the Institute for Scientific Information Citation Index as the most cited author on coral-reef ecology in America.  A Fulbright Senior Scholar and Aldo Leopold Fellow, among other awards, he serves on the editorial boards of several scientific journals.  Mark is past chair of the U.S. Marine Protected Areas Federal Advisory Committee, and the Ocean Sciences Advisory Committee for the U.S. National Science Foundation.  His public outreach includes TED talks and TV appearances.

The colossal hats (pukao) of monumental statues: an analysis of shape variability among the pukao or Rapa Nui - Sean Hixon

The archaeological record of Rapa Nui (Easter Island, Chile) is noteworthy for its massive statues (moai) that were transported across the island. Equally impressive are the colossal bodies of red scoria (pukao) that were placed on the heads of many moai. Explaining how the Rapa Nui assembled these stone monuments has remained open to debate and speculation. Experiments and calculations regarding the physics of stone movement help identify possible transport methods, and archaeological evidence, including analysis of moai and pukao variability, limit the range of likely transport methods. Efficient transport scenarios that involve small numbers of people best explain the archaeological record and are inconsistent with stone monument production driving past deforestation.

SEAN HIXON completed his undergraduate degree with honors at the University of Oregon in 2015 with majors in geology and archaeology. For his undergraduate honors thesis, he used remote sensing to help clarify the past method of stone monument construction on Easter Island (Rapa Nui). Sean completed his master’s degree in environmental archaeology at Pennsylvania State University in 2017 and is currently pursuing his dissertation field research in Madagascar with funding from a U.S. National Science Foundation Graduate Research Fellowship. His graduate work integrates archaeological and biogeochemical methods to test hypotheses regarding how past climate change and human behavior contributed to the extinction of Madagascar’s megafauna over the past 2,000 years.

IOMRC Auditorium, UWA

Thu 21 Mar 2019 To Thu 21 Mar 2019

1:00pm To 2:00pm