Tuesday, January 19, 2016

Rapoport's rule & lizards

Left. Anna Pintor with a flap-footed lizards (Pygopodiae). Photo credit: Image 
courtesy of James Cook University.Right pygopodids are legless geckos. JCM

James Cook University scientists have found lizards exposed to rain, hail and shine may cope better with extreme weather events predicted as a result of climate change than their fair-weather cousins.

A new study by JCU PhD student Anna Pintor, published in the journal Ecological Monographs, is one of the first to test the Climatic Variability Hypothesis (CVH) -- which proposes that animals living in environmentally variable areas should be able to tolerate more environmental fluctuations as a result.

This idea is a key assumption of the controversial Rapoport's Rule -- which states that a species at higher latitudes with variable weather conditions leads to the evolution of wider environmental tolerances which leads to a requirement for a larger range size.

Ms Pintor, along with supervisors Professor Lin Schwarzkopf and Professor Andrew Krockenberger from the Centre for Tropical Biodiversity and Climate Change, used three groups of Australian skinks for their analysis.

Their results confirm, in all three groups, that species living in regions with greater temperature variability have both greater environmental tolerances and wider ranges -- both in terms of latitude and altitude.

Andrew Krockenberger explains the importance of this result to advancing scientific thought "The literature is full of examples of species that do and don't fit Rapoport's rule," he said. "We've shown what is important is the actual underlying mechanism -- that species that can deal with a high degree of variability at a single site also end up with more extensive geographic ranges.

"Arguing about whether or not Rapoport's rule is valid is irrelevant and misses the point -- let's start making sure we understand the underlying process instead."

Lead author Anna Pintor said if we want to understand impacts of climate change in the future, we need to know how species' current distributions come about it the first place.

"Understanding underlying mechanisms like the CVH is one way to do that, but we need to do a lot more before we can tell exactly how species will be impacted and how to best help them deal with climate change."

Citation

Anna F. V. Pintor, Lin Schwarzkopf, Andrew K. Krockenberger. Rapoport's Rule: Do climatic variability gradients shape range extent? Ecological Monographs, 2015; 85 (4): 643 DOI: 10.1890/14-1510.1

2 comments:

  1. Is this comparison done between related species of skinks or between different populations of the same species?

    OR Hill

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    Replies
    1. no they "...used the three largest monophyletic lineages of lygosomine skinks endemic to the Australian mainland, namely the Carlia clade (Eugongylus group; genera Carlia, Lygisaurus, and Liburnascincus), the Egernia clade (Egernia group; genera Egernia, Bellatorias, Liopholis, Lissolepis, Tiliqua, and Cyclodomorphus) and the genus Ctenotus
      (Sphenomorphus group; genus Ctenotus)."

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