In message . com,
Raphanus writes
While Homo sapiens usually have 46 chromosomes there are individuals
with 45 chromosomes (Turner's syndrome), 47 chromosomes (Down,
Klinefelter's, XYY and XXY syndromes) and even 48 chromosomes (XXYY
syndrome). Most of these variants are fertile and able - with
individuals with the "normal" complement of 46 chromosomes - to produce
children.

Are there other species also with a variant chromosome count? Or do we
know? Homo sapiens is, no doubt, the species we know most about and
maybe such variation has eluded detection in other species?


Yes. Google for "chromosomal races". Rodents and shrews have a tendency
to throw up species with varying chromosome numbers. (But these tend to
be chromosomal fusions or fissions, rather than deletions or
duplications.)

For plants Google for "supplementary chromosomes" or "B chromosomes",
which refers to the case where plants have a variable number of small
chromosomes in addition to the main set. Also "cytotypes", which refers
to different chromosomal conditions - typically ploidy level. (I expect
that in most cases populations with different ploidy levels represent
different species, but plant taxonomists often treat them as elements of
a single species.)

Well known plants with diploid and tetraploid cytotypes include the
lesser celandine (Ranunculus ficaria) and the yellow archangel (Lamium
galeobdolon).


--
Stewart Robert Hinsley