TEE BIOLOGY OF ASCIDIANS
11
O C
: : - Y M J S N
D
l : : [
. .i -
E
50
P
Fro. 4. Breeding of ascidiana on Scottish west coast, as shown by percentage of samples
with incubating embryos (0-0) or larvae (.----a) (C-H, J, B). In A the
condition of gonads indicated breeding. In B, I and L embryos and larvae are not
represented separately. A, Pelonaiu corrugata; B, Dendrodoa groaaularia; C ,
Aplidium pailidurn; D, Sidnyum turbinatum; E, Aplidium nordmanni; F, A .
punetum ; 0, Polydinum aurantium ; H, Didemnum candidum ; I Diploaoma lkkrianum ; J, Liaaodinum argylleme ; K, Clavelina lepadiformia ; L, Botryllua achloaaeri.
Sea temperature in 1952, .--.. and in 1953. 0 - 0 (after Millar, 1958e).
In addition to examining the behaviour of one species in different
places we may look for evidence of temperature effects by comparing
the breeding seasons of several species in the same area, bearing in mind
the position which each occupies within its total geographical range.
Thus a group of species on the Scottish west coast shows a north boreoarctic species at the southern limit of its range breeding briefly in the
winter, south boreo-arctic species breeding over a long period, and
south boreal species with a short summer period (Fig. 4) (Millar, 1958a).
11
O C
: : - Y M J S N
D
l : : [
. .i -
E
50
P
Fro. 4. Breeding of ascidiana on Scottish west coast, as shown by percentage of samples
with incubating embryos (0-0) or larvae (.----a) (C-H, J, B). In A the
condition of gonads indicated breeding. In B, I and L embryos and larvae are not
represented separately. A, Pelonaiu corrugata; B, Dendrodoa groaaularia; C ,
Aplidium pailidurn; D, Sidnyum turbinatum; E, Aplidium nordmanni; F, A .
punetum ; 0, Polydinum aurantium ; H, Didemnum candidum ; I Diploaoma lkkrianum ; J, Liaaodinum argylleme ; K, Clavelina lepadiformia ; L, Botryllua achloaaeri.
Sea temperature in 1952, .--.. and in 1953. 0 - 0 (after Millar, 1958e).
In addition to examining the behaviour of one species in different
places we may look for evidence of temperature effects by comparing
the breeding seasons of several species in the same area, bearing in mind
the position which each occupies within its total geographical range.
Thus a group of species on the Scottish west coast shows a north boreoarctic species at the southern limit of its range breeding briefly in the
winter, south boreo-arctic species breeding over a long period, and
south boreal species with a short summer period (Fig. 4) (Millar, 1958a).