With the
full genome of a 6700 year old male aurochs being sequenced since 2013, it is
possible to get better insight on the genetic relationships between wild
aurochs populations and domestic cattle, if there was local introgression from
wild individuals and which genome regions were particularly influenced by domestication.
Now a summary of some recent papers.
The
whole-genome sequencing data placed this British aurochs as an outgroup to all
modern European cattle [1,2]. mtDNA suggested that Southern European and North-Central
European aurochs formed different genetic groups, the latter one being closer
to domestic cattle than North-Central European aurochs are [3]. Perhaps hence
the genetic distance of the British aurochs, but I tend to think that a
southern European aurochs would be an outgroup to cattle as well.
Nevertheless,
it seems confirmed that farmers did consciously breed wild aurochs into their
stock. Orlando 2015 found that British cattle breeds (in particular: Highland,
Dexter, Welsh Black, Kerry, White Park [2]) show substantial amount of
admixture with British aurochs, sharing many polymorphisms [1]. This suggests
that Neolithic farmers consciously bred aurochs into their stock, perhaps to
gain local climatic and immunologic adaptions for their cattle (those which,
after all, originated in the Near East) [1,2].
Orlando
2015 concluded: „Most European breeds
apparently developed in situ with no mitochondrial influence from local
aurochs, except perhaps Italy, Poland and Switzerland where B. primigenius mtDNA variants can be occasionally found in
modern and/or ancient cattle. “
The case
from Switzerland that he mentioned is described in a 2014 paper that reported
the skeleton of a small female bovine standing only about 1,10 meters high at
the withers, therefore being undoubtedly a domestic cow, dated to 5300-5000
years BP, but possessed a mtDNA P-haplotype variant of the European aurochs.
Therefore this individual is the result of local admixture – and further not a
first-generation hybrid because of its size. It again suggests intentional
breeding with (female) aurochs [4]. According
to Park et al. 2015, the Q haplogroup suggests limited local admixture as well
[1]. It is important to note that no modern domestic cattle have the P mtDNA
haplotype, which does not imply that all the nuclear genes introduced by the
interbreeding were lost as well, as long the lineage did not vanish.
So now we
have it confirmed that local aurochs did leave a genetic trace in European
domestic cattle. Evidence indicates that it happened only rarely, but in my
opinion this kind of evidence and the material we have is not able to determine
the quantity of such events.
However, I
see no reason to be euphoric over the results and draw conclusions like Italian
or British cattle being more of an European aurochs than other cattle.
An
interesting side note: Park et al. 2015 detected traces of zebuine components
in some Italian cattle (Chianina, Marchigiana and Romagnola) and East Asian cattle
(Hanwoo and Wagyu). But it is also possible that those are alleles that other
taurine cattle have lost [2].
It was found
that domestication affected genes for neurobiology, growth, muscle development,
metabolism and immunology [2].
Last but not least, an interesting
passage from Orlando 2015 that brings up some aspects of domestication that
might not be that often considered:
„Animal
domestication is, however, likely to not just have remodeled the sequence of
the
genome. Micro- biomes, for example, might also have changed in relation
with dietary
shifts, which possibly affected important phenotypic traits,
ranging from the physiological
to the behavioral. As wild and domestic animals
show subtle changes in brain gene
expression networks, transcrip- tional
changes are also likely to have been an early
component of domestication.“
References
[1] Orlando,
L.: First aurochs genome reveals the
breeding history of British and European cattle, 2015.
[2] Park et
al.: Genome sequencing of the extinct
Eurasian wild aurochs, Bos primigenius, illuminates the phylogeography and
evolution of cattle. 2015.
[3] Lari et al.: The
complete Mitochondrial genome of an 11,450-year-old Auerochsen (Bos
primigenius) from Central Italy. 2011.
[4] Schibler,
Elsner & Schlumbaum.: Incorporation
of aurochs into a cattle herd in Neolithic Europe: single event or breeding?
2014.
Interesting article, thank you.
ReplyDeleteMr Foidl,
ReplyDeleteI am a professor of biology at the University of Aix-Marseille. I often read your blog and appreciate also your illustrations. As I shall desire to discuss with you of a project, could you contact me at this address eric.faure@univ-amu.fr and then delete this message.
Sincerely yours,
Eric Faure