Gecko phylogeography in the Western Indian Ocean region: the oldest clade of Ebenavia inunguis lives on the youngest island

Abstract

Aim We studied the gecko genus Ebenavia to reconstruct its colonization history, test for anthropogenic versus natural dispersal out of Madagascar, and correlate divergence date estimates of our phylogeny with geological age estimates of islands in the region.Location Madagascar and surrounding islands of the Western Indian Ocean (Comoros, Mayotte, Mauritius, Pemba). MethodsWe reconstructed the phylogeny of Ebenavia covering its entire geographical range using a molecular data set of three mitochondrial and two nuclear markers. We estimated divergence times based on calibrations using (1) previously calculated mutation rates of mitochondrial markers, (2) a combination of these rates with old or (3) young geological age estimates for some of the islands inhabited by the genus, and (4) an independent data set with fossil outgroup calibration points.Results Ebenavia inunguis, one of two recognized species of the genus, comprises multiple ancient evolutionary lineages. The earliest divergence within this complex (Miocene, 13-20 Ma; 95% credibility interval [CI]: 4-29 Ma) separates the population of the Comoros Islands, excluding Mayotte, from all other lineages. The age estimates for island lineages coincide with the geological age estimates of the islands except for Grand Comoro, where the age of the local clade (3-5 Ma; 95% CI: 2-7 Ma) significantly predates the estimated island age (0Á5 Ma). A clade from north Madagascar + Mayotte + Pemba is estimated to have diverged from an eastern Malagasy clade in the Miocene. Main ConclusionsOur results suggest that Grand Comoro Island is geologically older than previously estimated. The islands of the Comoros and Pemba were probably colonized via natural dispersal out of Madagascar (> 1000 km in the case of Pemba). Mauritius was most likely colonized only recently from eastern Madagascar via human translocation.

Tropical specialist vs. climate generalist: Diversification and demographic history of sister species of Carlia skinks from northwestern Australia

“…Hawlitschek et al. () also recently found a gecko lineage much older than the estimated geological island age where it occurs.…”

Geographical and temporal origins of terrestrial vertebrates endemic to Taiwan

“…Therefore, we advocate for the first explanation of Hawlitschek et al. () that the divergence events of extant species occurred before their colonization into Taiwan, and extinctions within the ancestral taxa resulted in relict populations in Taiwan (Mays et al., ; Wang et al., ). This reconciliation does not necessarily oppose the time window of colonization events occurring from c .…”

“…Hawlitschek et al. () provided two potential explanations: (a) the sister clades of island lineages have recently gone extinct, or the historical stepping‐stone dispersal routes have submerged; (b) the geological ages of the islands were largely underestimated. With respect to Taiwan, a much earlier emergence of this island has been suggested to reconcile with the earlier timing of colonization (Li et al., ).…”

“…With respect to Taiwan, a much earlier emergence of this island has been suggested to reconcile with the earlier timing of colonization (Li et al., ). However, unlike oceanic islands whose geological ages are easily underestimated due to irregular volcanic activities (Hawlitschek et al., ; Parent et al., ), palaeogeological studies (Sibuet & Hsu, ; Teng, ) and palaeontological information (i.e. fossils; Kawamura et al., ) have provided strong and widely accepted evidence regarding the timing of the emergence of Taiwan.…”

“…In other regions of the world, it has been reported that the ages of island endemic taxa significantly pre-date the ages of islands (Parent et al, 2008;Renner, Strijk, Strasberg, & Thébaud, 2010). Hawlitschek et al (2017) provided two potential explanations:…”