What story does geographic separation of insular bats tell? A case study on Sardinian rhinolophids

PLoS One. 2014 Oct 23;9(10):e110894. doi: 10.1371/journal.pone.0110894. eCollection 2014.

Abstract

Competition may lead to changes in a species' environmental niche in areas of sympatry and shifts in the niche of weaker competitors to occupy areas where stronger ones are rarer. Although mainland Mediterranean (Rhinolophus euryale) and Mehely's (R. mehelyi) horseshoe bats mitigate competition by habitat partitioning, this may not be true on resource-limited systems such as islands. We hypothesize that Sardinian R. euryale (SAR) have a distinct ecological niche suited to persist in the south of Sardinia where R. mehelyi is rarer. Assuming that SAR originated from other Italian populations (PES)--mostly allopatric with R. mehelyi--once on Sardinia the former may have undergone niche displacement driven by R. mehelyi. Alternatively, its niche could have been inherited from a Maghrebian source population. We: a) generated Maxent Species Distribution Models (SDM) for Sardinian populations; b) calibrated a model with PES occurrences and projected it to Sardinia to see whether PES niche would increase R. euryale's sympatry with R. mehelyi; and c) tested for niche similarity between R. mehelyi and PES, PES and SAR, and R. mehelyi and SAR. Finally we predicted R. euryale's range in Northern Africa both in the present and during the Last Glacial Maximum (LGM) by calibrating SDMs respectively with SAR and PES occurrences and projecting them to the Maghreb. R. mehelyi and PES showed niche similarity potentially leading to competition. According to PES' niche, R. euryale would show a larger sympatry with R. mehelyi on Sardinia than according to SAR niche. Such niches have null similarity. The current and LGM Maghrebian ranges of R. euryale were predicted to be wide according to SAR's niche, negligible according to PES' niche. SAR's niche allows R. euryale to persist where R. mehelyi is rarer and competition probably mild. Possible explanations may be competition-driven niche displacement or Maghrebian origin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Africa
  • Africa, Northern
  • Algorithms
  • Animals
  • Area Under Curve
  • Biodiversity
  • Chiroptera / physiology*
  • Ecology
  • Ecosystem
  • Geography*
  • Italy
  • Mediterranean Region
  • Models, Biological
  • Software

Grants and funding

DR and LB were funded by Italian Ministry of the Environment and the Protection of Land and Sea, CIG nr. 464598541B (www.minambiente.it). HR was funded by the Programme Investigador FCT, IF/00497/2013 (www.fct.pt). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.