Doing it in the Dark: Hybridization in Bats

Two studies explore possible hybridization events in bats.

Hybrid bats. It could be the title of a horror movie, but it is actually serious science. Two recent papers explored the genetics of several bat species to figure out whether there is (or has been) any hybridization. The findings were not too bat…

bat.jpg

A Natterer’s Bat (from: https://www.nederlandsesoorten.nl/)

 

Bat Complex

The first paper appeared in the Journal of Biogeography. Emrah Çoraman and his colleagues focused on the Natterer’s bat (Myotis nattereri) complex, which is distributed in Northwest Africa, Europe and parts of the Middle East. Based on one mitochondrial and four nuclear markers, the researchers reconstructed the evolutionary history of this bat complex. The analyses revealed four main groups. Let’s have a look at them. The colors in the text correspond to the figure below.

 

Four Lineages

A central lineage (yellow), ranging from Ireland to Ukraine, probably survived the last glacial period in three refugia: western Balkans, Greece and western Anatolia. After the ice ages, these populations expanded into Europe. We find the second lineage (blue) in Italy. Here, there are two separate groups: one in northern Italy and one in southern Italy. They meet and probably hybridize in the central Appenine Mountains. The third lineage (green) houses bats from the Iberian Peninsula and Northern Africa. Finally, the fourth lineage (reddish brown) represents the lesser known eastern part of the distribution. This lineage is comprised of four subgroups, which have an interesting history that we will explore in more detail.

bat phylogeny.jpg

The (a) evolutionary history and (b) distribution of the Myotis nattereri complex (from Çoraman et al. 2018 Journal of Biogeography)

 

Hybridization Events

As you can see in the figure above, the evolutionary history of this bat complex is quite…well…complex. It involves several hybridization events, resulting in a reticulated phylogeny. For example, there has been gene flow between the blue and yellow lineages. Probably, the blue lineage expanded out of Italy and come into contact with the yellow one.

Another hybridization event occurred in the eastern part. Expanding population first came into contact with the local lineage in Anatolia. They acquired the mtDNA from this lineage and continued their expansion to Israel where they obtained mtDNA from the resident populations. Interestingly, the Israeli populations went extinct but their genes live on in another species.

 

Cryptic Species

The second paper – in the journal Ecology and Evolution – delved into the genetics of three cryptic species of long‐eared bats (Plecotus auritus, P. austriacus, and P. macrobullaris). Cryptic species are reproductively isolated, but morphologically they are identical. Tommy Andriollo and his colleagues postulated that the extensive phenotypic overlap and observation of morphologically intermediate individuals may hide rampant hybridization. To test this idea, they sampled 349 individuals and genotyped them with a mitochondrial marker and microsatellites. Surprisingly, no sign of hybridization was detected suggesting that these three species are biologically separated. Hybridization is a common phenomenon, but that doesn’t mean you will always find it.

Plecotus auritus.jpg

A Brown Long-eared Bat (from: http://www.freenatureimages.eu/)

 

References

Andriollo, T., Ashrafi, S., Arlettaz, R. & Ruedi, M. (2019) Porous barriers? Assessment of gene flow within and among sympatric long‐eared bat species. Ecology and Evolution, 8(24):ece3.4714.

Çoraman, E., Dietz, C., Hempel, E., Ghazaryan, A., Levin, E., Presetnik, P., Zagmajster, M & Mayer, F. (2019) Reticulate evolutionary history of a Western Palearctic Bat Complex explained by multiple mtDNA introgressions in secondary contact. Journal of Biogeography, 46:343-354.

3 thoughts on “Doing it in the Dark: Hybridization in Bats

  1. […] Further analyses (based on f-statistics) supported the notion that hybridization was a frequent phenomenon in baboon evolution. The authors write that “no one simple dichotomously branching tree accurately reflects all aspects of genomic differentiation among extant baboon species.” Therefore, they reconstructed the evolutionary history of these primates taking into account gene flow between several species. The result is a complicated network with multiple interconnections and different amounts of exchanged DNA. These reticulated scenarios seem to be a common aspect of mammalian evolution (see for instance whales, cows and bats). […]

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