P O L I S H P O L A R R E S E A R C H ( P O L P O L A R RES ) 305—317 1986 P O L I S H P O L A R R E S E A R C H ( P O L P O L A R RES ) / 3 305—317 1986 P O L S K I E B A D A N I A P O L A R N E 305—317 Jacek S I C I Ń S K I L a b o r a t o r y of Polar Biology, D e p a r t m e n t of General Zoology, Institute of Environmental Biology, University of Łódź,
ul. S. Banacha 12/16, 90-237 Łódź, P O L A N D
Application of the dendrite analysis
in the discussion on the
biogeography of the Antarctic
A B S T R A C T : The m e t h o d of construction and division of dendrites proposed by F l o r e k et al. (1951) was used for defining of the Antarctic biojjeographic areas. T h e affinity matrices of K n o x a n d L o w r y (1977) resulting f r o m the analysis of the distribution of Antarctic Polychaeta a n d Amphipoda were t a k e n as a basis for dendrite construction T h e results of the present analysis are c o m p a r e d with the conclusions of these a u t h o r s and similarities a n d differences are discussed o n the b a c k g r o u n d of the hitherto published biogeographic divisions of Antarctica.
K e y w o r d s : Antarctica, biogeography.
1. Introduction
The Southern Ocean distincly differs from other parts of the World Ocean in its specific benthos, plankton and nekton communities. Particular animal groups inhabiting this area have a high percentage of endemic species, genera and even families. O p e n to debate, on the other hand, is the division of this area into biogeographical regions. A proposal of such dividing was put forward for instance by K n o x and L o w r y (1977) who have used a comprehensive knowledge of the distribution of two groups of benthos rich in species, namely Amphipoda and Polychaeta. The basis of such a n analysis were the affinity matrices of selected Antarctic localities. These matrices enabled to g r o u p biogeographical areas separately for Amphipoda and for Polychaeta ( K n o x and L o w r y 1977, Figs 3 and 7, pp. 438 and 444).
3 0 6 Jacek Siciński According to the present a u t h o r , there is a possibility of g r o u p i n g the localities by m e a n s of the mathematically objective m e t h o d p r o p o s e d by F l o r e k et al. (1951). Using such a m e t h o d of ordering i n f o r m a t i o n included in affinity matrices of K n o x a n d L o w r y (1977) the a i m of the present a u t h o r was to answer the following q u e s t i o n s : 1) is the g r o u p i n g of localities into biogeographical areas, which is p r o p o s e d by t h e a b o v e cited a u t h o r s , the only possible o n e a n d the best o n e ?; 2) will conclusions d r a w n f r o m the d e n d r i t e analysis be in agreement with the conclusions of the a b o v e cited a u t h o r s ?
2. Methods
O n the basis of i n f o r m a t i o n o n the m u t u a l affinity between the localities in q u e s t i o n ( K n o x a n d L o w r y 1977) their shortest - d e n d r i t e s have been constructed according t o F l o r e k et al. (1951) separately for Amphipoda a n d Polychaeta (Figs 1 a n d 2). In such o r d e r i n g of the
N.Z.SUB. IS 85 KERGUELEN HEARD IS " FALKLAND IS 59 66 65 SOUTH " GEORGIA" 64 78 MARION I. 66 MACQUARIE I. 62 ANTARCTIC PENINSULA 58 SOUTH SHET-LAND IS 62 SOUTH ORK-NEY IS
TIERRA DEL FUEGO
- ENDERBY LAND 62 DAVIS SEA
61 MCMURDO SOUND 61 CAPE ADARE 68 ADELLE COAST d w' w" 85 78 1,0897 - 0,9500 68 1,1471 66 1,0303 65 1,0154 0,9998 64 1, 0156 0,9838 62 1,0323 61 1,0164 0,9831 59 1, 0339 58 1, 0172
Fig. 1. D e n d r i t e of localities constructed o n the basis of the affinity matrix of K n o x a n d L o w r y (1977) for Polychaeta (affinities are substituted by distances; in the table within the figure the natural division of t h e dendrite is presented, where d s t a n d s for distances expressed in percent, w' q u o t i e n t s of neighbouring distances, w " — q u o t i e n t s indicating
the m a t h e m a t i c a l strength of given divisions)
localities those of the highest affinity are n e i g h b o u r i n g each other. T h e n , the n a t u r a l division of t h e dendrites into p a r t s was carried out using the F l o r e k et al. (1951) m e t h o d which these a u t h o r s present as follows: " T h e n u m b e r of parts, k, into which the set Z built of n elements is divided in n a t u r a l way, may be estimated by the following m e t h o d : all sections (distances = d ; J. S.) occurring in the d e n d r i t e F (Z) are a r r a n g e d
Application of the dendrite analysis 3 0 7 in decreasing order. Let d j , d2, . . . d „ _ ! stand for the lengths of these
sections. We set the q u o t i e n t s of lengths (distances; J. S.) between a d j a c e n t sections: w2
dL
d2
w , = d 2 d3
..., W „ _ ! = -. W e can say that the set Z falls in the n a t u r a l way into к parts, if wk < wk + 1 for every к = 2, 3, ...и —1.
Of the two n a t u r a l divisions the division into к p a r t s is better (stronger) t h a n the division into m p a r t s when wk< wm. " Because K n o x a n d
L o w r y (1977) have estimated the affinities a n d the m e t h o d of F l o r e k et al. (1951) is based on the distances, the affinities in dendrites were
N.Z.SUB. IS 89
BURDWOOD BANK
82
KERGUELEN 87 T1ERRA DEL 85 SOUTH 71 GEORGIA HEARD IS 89 MARION I. 89 MACJIJARIE I. FUEGO 60 FAIKLAND IS 78 ADELIE COAST 70 ROSS SEA 72 DAVIS SEA S0L'TH SHE 'LANC IS 57 ANTARCTIC PENINSULA SOU^H ORK-NEY IS 89 87 1,023C 85 1,0235 82 1,0366 78 1, 0513 72 1,0833 71 1, 0141 70 1, 0143 5" ', 0448 65 1,0152 50 1000 0,9.995 0,9874 0,9850 С.9705 0,9998 0,9708 C,9229
Fig. 2. Dendrite of localities constructed on the basis of the affinity matrix of K n o x and L o w r y (1977) for Amphipoda (symbols as in Fig. 1)
substituted by distances calculated f r o m the e q u a t i o n : d = 100 —s, where " d " stands for distance, and "s" affinity in percent. T h e values w " (Figs 1—4) correspond to the m a t h e m a t i c a l strength of each division, indicating the value of discontinuity in the series of q u o t i e n t s w ' (Figs 1, 2). T h e lower is this value, the stronger is the division. S o m e i n f o r m a t i o n s o n the dendrite division are to be found also in the p a p e r by R o m a n i s z y n (1970). Dendrites constructed in this way a n d their mathematically accep-table divisions, constitute the basis of the present analysis.
3. Results
T h e r e are several possibilities of dividing of b o t h dendrites (Figs 3, 4); each of these divisions has a different m a t h e m a t i c a l strength. As the mathematically strongest division may be not necessarily t h e most proper for biogeographical divisions it is necessary to discuss each of them.
3 0 8 Jacek Siciński
Polychaeta
Division 1 of the dendrite (w" = 0.9500) (Fig. 3) is the strongest of the four and exhibits a highest degree of generalization. It distinguishes three groups of areas, of which the first comprises Auckland and Campbell Islands, the second Macquarie and M a r i o n Islands, the third — all the remaining localities. This division indicates to a considerable homogeneity of the fauna of Polychaeta within all the localities of the Antarctic including Kerguelen and Heard Islands and the Magellanic area, and at the same time it indicates to significant differences between the three so distinguished groups. However, this division does not contribute much to solving the problem of biogeographical division of the Antarctic. O n the other hand divisions 2 and 3, and particularly the latter can be well used for this purpose. In respect to mathematical strength, both these divisions are equivalent. The latter, which seems to be more justified from the biogeographical point of view, distinguishes 7 biogeographical areas:
1) East Antarctic
2) West Antarctic (Scotia Arc with the Antarctic Peninsula) 3) Magellanic
4) Kerguelen and Heard Islands 5) M a r i o n Island
6) Macquarie Island
7) Auckland and Campbell Islands.
Division 2 stresses additionally a strong affinity between Tierra del Fuego and Falkland Islands on the one hand and the Antarctic Peninsula and South Shetland Islands on the other. Division 4 (w" = 0.9998), which is- mathematically very weak, distinguishes the Scotia Arc, the Antarctic Peninsula and the Eastern Antarctic as one separate area. Being very weak in comparison with the others, this division may be ignored.
Amphipoda
In the case of Amphipoda biogeographical division carried out o n the basis of the distribution of Amphipoda is less univocal t h a n in the case of Polychaeta. There are as much as 7 possible divisions of the dendrite (Fig. 4). The strongest one (division 1, w" = 0.9229) combines Tierra del Fuego with Falkland Islands, leaving other localities as separate groups. This division indicates to considerable differences a m o n g the faunas of Amphipoda of all localities in question and consequently, in contrast to Polychaeta, to the higher variability of the a m p h i p o d fauna as a whole. As in the case of Polychaeta, this strongest division
contri-N. Z.SUB. IS I KERGUELEN. HEARD IS MARION I. MACQUARIE I. FALKLAND IS -.SOUTH _ GEORGIA ANTARCTIC PENINSULA
I
SOUTH SHET LAND IS I SOUTH ORK NEY IS TIERRA DEL "FUEGO 1. w " = 0 , 9 5 0 0-ENDERBY LAND DAVIS SEA MCMURDO SOUND CAPE ADARE
ADELIE COAST N.Z.SUB. IS FALKLAND - _TIERRA DEL FUEGO 2.w"= 0,9831 KERGUELEN HEARD IS MARION I. MACQUARIE I. SOUTH _ GEORGIA ANTARCTIC PENINSULA SOUTH SHET LAND IS
-ENDERBY LAND DAVIS SEA
SOUTH ORK NEY IS MCMURDO SOUND CAPE ADARE ADELIE COAST N.Z.SUB. IS N.Z.SUB.IS KERGUELEN-HEARD IS MARION I MACQUARIE I FALKLAND IS DEL I FUEGO С 3.W" = 0,9838 KERGUELEN i SOUTH 1 HEARD IS GEORGIA I 1 MARION I. 1 ANTARCTIC PENINSULA MACQUARIE I. SOUTH SHET
LAND IS SOUTH ORK NEY IS
TENDERBY LAND DAVIS SEA MCMURDO SOUND CAPE ADARE
FALKLAND IS JERRA DEL
r U t b u ADELIE COAST Д. w" = 0,9998 SOUTH GEORGIA ANTARCTIC PENINSULA SOUTH SHET LAND IS
-ENDERBY LAND- - DAVIS SEA MCMURDO SOUND CAPE ADARE SOUTH ORK
NEY IS ADELIE COAST
Fig. 3. F o u r possible divisions of the dendrite f r o m Fig. 1 (Explanations in the text a n d in Figs 1 a n d 2)
3 1 0
butes little to the biogeographieal dividing of the Antarctic. In this case each locality forms a separate group. Divisions 2 and 3 have similar mathematical strengths and are very similar to divisions 2 and 3 of the dendrite based on the distribution of Polychaeta (Fig. 3). Division 2 (Fig. 4) distinguihes similar areas, and division 3, similarly as in the case of Polychaeta, stresses the faunistic similarity of two smaller areas. Divisions 4 and 5, which are mathematically slighty weaker, are very similar. They differ only in respect to Burdwood Bank, which may result from the insufficient knowledge of this locality as it was pointed out by K n o x • and L o w r y (1977). Divisions 6 and 7 are very weak and seem to be little justified from the biological point of view.
4. Discussion
An analysis of an affinity matrix of the localities which was proposed on the basis of the distribution of Polychaeta inclined K n o x and L o w r y (1977) to distinguisch three areas: A. Subantarctic (with King Edward Island, Macquarie and possibly Auckland and Campbell Island), B. Antarctic (with the whole coastline of the continent together with the Scotia Arc, Kerguelen and Heard Islands), and C. Magellanic (including Tierra del Fuego and Falkland Islands). F r o m the viewpoint of the dendrite analysis, such a division is weakly justified. Division 4 (Fig. 3), which, as it was mentioned earlier, is mathematically very weak, is closest to such a concep-tion. According to this division 4, Kerguelen and Heard Islands constitute a separate area; the subantarctic islands Marion, Macquarie and Auckland and Campbell, should be then considered as three independent areas as well. Division 3 is the most justified one (Fig. 3) from the biological point of view.
In the case of Afnphipoda, the division 2 (Fig. 4), which is mathemati-cally strong, should be considered the best one in biogeographieal terms. It accords with the division proposed by K n o x and L o w r y (1977), except the subantarctic islands, which constitute here separate areas.
The final conclusion of K n o x and L o w r y (1977) concerning the biogeographieal division of the Antarctic on the basis of the distribution of Polychaeta differs from the scheme appearing directly from the affinity matrix. They state: "... we believe they g r o u p mainly as a large Antarctic area which includes the whole coastline, including the Scotia Arc and a smaller Magellanic area which is not very convicingly separated. The Subantarctic area includes only Macquarie and M a r i o n Islands, b o t h of which show some relationship with the Antarctic, and Auckland and Campbell with New Zealand". At the same time K n o x and L o w r y (1977) stressed that the regionalization on the basis of the distribution
KI 7 CL I • 1С BARDWOOO N.Z. 5UB. 15 BANK 1. W = 0,9229 KERGUELEN HEARD IS MARION I . MACQUARIE I.
TIERRA SOUTH SOUTH SHET "DEL FUEGO GEORGIA LAND IS
FALKLAND ADELIE ANTARCTIC IS COAST PENINSULA
ROSS SEA SOUTH ORK
I NEY IS DAVIS SEA N.ZSUB.IS GUROWOOO BANK 2 . W " = 0,9705 KERGUELEN L T I E F R A N.Z.SUB. IS KERGUELEN HEARD IS " MARION I MACQUARIE I. BURDWOOD BANK | 3 . W " = 0 , 9 7 0 8
TIERRA SOUTH SOUTH SHET DEL FUEGO GEORGIA LAND IS
FALKLAND IS ADELIE COAST ANTARCTIC PENINSULA 1 ROSS SEA 1 SOUTH ORK NEY IS DAVIS SEA ы t ci ID ic BURDWOOO N.Z. SUB. IS BANK U. W * = 0 , 9 8 6 0 KERGUELEN [TIERRA HEARD IS MARION I. MACQUARIE I
DEL FUEGS GEORGIA LAND IS
FALKLAND IS
SOUTH SOUTH SHET
ADELIE ANTARCTIC COAST PENINSULA
ROSS SEA SOUTH ORK NEY IS N Z.SUB. IS KERGUELEN. HEARD IS MARION I MACQUARIE I. DAVIS SEA BURDWOOD BANK 5 . W " = 0,9874
.TIERRA .SOUTH SOUTH SHET DEL FUEGO I GEORGIA I LAND IS I 1 FALKLAND IS 1 ADELIE COAST ANTARCTIC PENINSULA ROSS SEA I 1 SOUTH ORK NEY IS 1 DAVIS SEA N.Z.SUB. IS KERGUELEN HEARD IS " MARION I.
I
MACQUARIE I. BURCMIOOO BANK 6 . W " = 0 , 9 9 9 5TIERR SOUTH SOUTH SHET DEL FUEGO GEORGIA LAND IS
FALKLAND IS ADELIE COAST ANTARCTIC PENINSULA
ROSS SEA SOUTH ORK NEY IS DAVIS SEA N Z.SUB.IS KERGUELEN HEARD IS MARION I. MACQUARIE I. BURDWOOD BANK 1 L _ .TIERRA . DEL FUEGO I 1 FALKLAND IS 7. W " = 0 , 9 9 9 8
Fig. 4. Seven possible divisions of the dendrite f r o m Fig. 2 (Explanations in the text and in Figs 1 and 2)
SOUTH .SOUTH SHET GEORGIA 1 LAND IS I ADELIE COJST ANTARCTIC PENINSULA I ROSS SEA 1 SOUTH ORK NEY IS DAVIS SEA
Application of the dendrite analysis 3 1 1
of Polychaeta differs from the grouping of localities resulting from the distribution of Amphipoda. In the opinion of the present a u t h o r this conclusion seems to be controversial. It appears that the grouping of localities in the case of both animal groups can be similar. The difference between the two divisions of K n o x and L o w r y (1977) results from the accepted affinity limit value of 25 „ (localities of the affinity equalling or exceeding this value are combined in groups by these authors). However, this value must not be an essential and only one for each matrix taken separately and for both matrices taken together. It seems that a natural division of dendrites which is based on a mathematically objective criterion evidences for the concept of similar regionalization for both animal groups. The following remarks can be put forward. The final division of K n o x and L o w r y (1977) based on the fauna of Polychaeta is almost identical with the mathematically strongest division of the dendrite (Fig. 3—1). If, however, such a grouping was to be accepted then, consequently, the zoogeographical division made on the basis of the fauna of Amphipoda should correspond to the division 1 of the dendrite presented in Fig. 4, because only these two divisions are camparable as regards their mathematical strength. Nevertheless, these strongest divisions indicate rather to the difference in the faunas of the two groups (homogeneity of the fauna of Polychaeta and heterogeneity of the fauna of Amphipoda), then the possibility of different biogeographieal divisions. In respect to the mathema-tical strength, the division 1 is followed in both dendrites by divisions 2 and 3. In view of the present consideration important divisions are division 2 for Amphipoda (Fig. 4) and division 3 for Polychaeta (Fig. 3) In both cases the grouping of localities is almost identical (the separate position of Burdwood Bank in the case of Amphipoda and of Adelie Coast in the case of Polychaeta may be ignored, taking into account the remark of K n o x and L o w r y (1977) about the insufficient knowledge of these regions. The peculiarities of the faunas of both animal groups cause that the divisions of both dendrites are different, especially in the case of the mathematically strongest divisions. Nevertheless the more detailed regionalization on the basis of polychaete fauna is possible, although it has to be based obviously on more subtle criteria. Consequently, to th^ present author's mind, the grouping of localities can be the same, wit i biogeographic distinction between East and West Antarctic, in the cai-e of both animal groups. This is in accordance, in respect to Polychaeta, with the conclusions of A v e r i n c e v (1972) from the distribution of Polychaei i
Errantia.
The majority of a u t h o r s dealing with biogeographic regionalization of the Southern Ocean consider the West Antarctic and East Antarctic as separate regions ( E k m a n 1953, K n o x 1960, A n d r i a s h e v 1965, K u s a k i n
3 1 2 Jacek Siciński
A r n a u d 1984) and only few a u t h o r s regard the whole Antarctic as one region ( P o w e l l 1965, D e l l 1972).
There are different opinions on the biogeographic status of South Georgia. E k m a n (1953), K n o x (1960), A n d r i a s h e v (1965) and P o w e l l (1965) are treating this island as a province of the equal rank as a n Antarctic province, encompassing the continent together with Scotia Arc and Bouvet<j>ya and Heard Island. K u s a k i n (1967) and A v e r i n c e v (1972) proposed to separate South Georgia subregion equivalent to the West-and East-Antarctic subregions. H e d g p e t h (1969, 1970) West-and D e l l (1972) suggested for South Georgia a particular rank — a district in the Scotia subregion. Finally K o t t (1969) divided the Antarctic region in two pro-vinces — a continental one and a South Georgia province. This last one would encompass the Antarctic Peninsula and the whole Scotia Arc. Biogeographic rank of South Georgia resulting from the dendrite analysis (Figs 3 and 4) fits the best to the concept of K o t t (1969). It seems that basing on the distribution of Polychaeta and Amphipoda South Georgia should be included to the West Antarctic. It is to be stressed, however, that South Georgia faunistically shows similarities on o n e hand to the Magellanic area and to the East Antarctic area o n the other, and in the case of Polychaeta also to the Kerguelen Islands (Figs 3 and 4).
The faunistic affinities of the subantarctic islands are very interesting. F r o m the analysis of the dendrites divisions (Figs 3 and 4) it follows that Macquarie Island, Kerguelen and Heard Islands, M a r i o n Island and Auckland and Campbell Islands constitute four separate biogeographic areas. Such a division is near to the concept of K u s a k i n (1967) resulting from the analysis of the distribution of Isopoda. This a u t h o r distinguished the Kerguelen region, dividing it however in three subregions: Macquarie, Kerguelen and Marion. K n o x and L o w r y (1977) are stressing as well that the said islands because of their a m p h i p o d fauna specifity m a k e them difficult for grouping. In general, however, most of the a u t h o r s join Prince Edward, Marion, Crozet, Kerguelen, Heard and Macquarie islands in one unity ( K n o x 1960, A n d r i a s h e v 1965, P o w e l l 1965, H e d g p e t h 1969, A v e r i n v e v 1972, D e l l 1972, C a n t e r a and A r n a u d 1984). Most of the a u t h o r s are of the opinion that the Auckland and Campbell Islands should be considered as an area separate from all other subantarctic areas. Only K o t t (1969) included these islands into the Kerguelen province together with Macquarie, Kerguelen and Heard Islands.
5. Conclusions
I. The dendrite analysis of data included in the matrices of K n o x and L o w r y (1977) allowed to g r o u p objectively particular Antarctic
Application of the dendrite analysis 3 1 3
localities; this grouping confirms and illustrates a n u m b e r of con-clusions of these authors regarding the biogeographical division of the Antarctic and also the conclusions about the pecularities of the faunas of both animal g r o u p analysed. O n the other hand this dendrite analysis makes part of their conclusions disputable. II. The mathematically strongest divisions of b o t h dendrites and their
structure confirm and illustrate the homogeneity of the Antarctic fauna of Polychaeta and a considerable variability of the fauna of
Amphipoda.
III. The natural divisions of both dendrities with several possibilities of grouping illustrates well the idea of K n o x and L o w r y (1977) that the subantarctic islands (Kerguelen and Heard, Marion, Macquarie as well as Auckland and Campbell) should be considered four distinct zoogeographic areas. This is especially clear in the analysis of the distribution of Amphipoda.
IV. The structure of the dendrites illustrates well the concept of the exceptional position of South Georgia as a transitional area, which is particularly obvious in the case of Polychaeta. This area is a place in which the dendrite branches into four different biogeographical areas.
V. The proposal of distinguishing biogeographical areas on the basis of Polychaeta distribution which is here presented differs from the concept of K n o x and L o w r y (1977). The grouping of localities in the case of both animal groups discussed would be similar with a reservation that the differences in the case of polychaete fauna are only more subtle. Thus the presently proposed division of the Antarctic into areas is in general in agreement with A v e r i n c e v ' s (1972) division based on the distribution of Polychaeta Errantia. VI. The opinion of K n o x and L o w r y (1977) that in the case of the
analysis of the distribution of Polychaeta the Magellanic area cannot be distinctly enough separated from the Antarctic area, seems to be controversial, and, consequently, the combining the two areas is also disputable. As it is shown in Fig. 3 the Magellanic area is distinctly separated.
VII. Disregarding the strongest divisions of b o t h dendrites as contributing little to the problem of the Antarctic biogeographical regionalization as well as the weakest divisions, the present a u t h o r proposes the following division identical for Amphipoda and for Polychaeta (Fig. 5):
A. Magellanic area
B. West Antarctic area ( = Scotia Arc with the Antarctic Peninsula) C. East Antarctic area
Fig. 5. M a p of the Antarctic with proposed biogeographic areas
(1 Tierra del Fuego, 2 — B u r d w o o d Bank, 3 — F a l k l a n d Islands, 4 - S o u t h Georgia, 5 — S o u t h O r k n e y Islands, 6 — S o u t h Shetland Islands, 7 Antarctic Peninsula, 8 — E n d e r b y L a n d , 9 — Davis Sea, 10 — Adelie Coast, 11 - C a p e Adare, 12 — M c M u r d o Sound, 13 — Ross Sea, 14 — M a r i o n Island, 15 — Kerguelen Island, 16 — H e a r d Island, 17 — M a c q u a r i e Island, 18 — Auckland Island, 19 — C a m p b e l l I s l a n d ; A — Magellanic area, В — West Antarctic area, С — East Antarctic area, D — M a r i o n Island, E— Kerguelen a n d H e a r d Islands, F — M a c
Application of the dendrite analysis 3 1 5
E. Kerguelen and Heard Islands F. Macquarie Island
G. Auckland and Campbell Islands
VIII. Separating the East Antarctic from the West Antarctic as distinct zoogeographical units is more justified than combining them into one area.
6. Резюме
И с п о л ь з у я т а б л и ц ы сходства Н о к с а и Л о у р и (1977), р а з р а б о т а н н ы е на основе распределения антарктических Polychaeta и Amphipoda, п р е д с т а в л е н ы п р е д л о ж е н и я д л я м а т е м а т и ч е с к о й группировки антарктических р а й о н о в . П р и п о м о щ и м е т о д а Ф л о р к а и др. (1951) б ы л и составлены с а м ы е к о р о т к и е д е н д р и т ы р а й о н о в и проведено их м а т е м а т и -ческое разделение (рис. 1, 2, 3, 4). С м а т е м а т и ч е с к о й точки зрения с а м ы е с и л ь н ы е разделения обоих д е н д р и т о в под-т в е р ж д а ю под-т и х о р о ш о о б о с н о в ы в а ю под-т гипопод-тезу Н о к с а и Л о у р и (1977) о б о д н о р о д н о с под-т и фауны антарктических Polychaeta и о з н а ч и т е л ь н о м р а з н о о б р а з и и ф а у н ы Amphipoda. И з а н а л и з а о б о и х д е н д р и т о в следует, что субантарктические о с т р о в а (Кергелен, Хёрд, М а р и о н , М а к к у о р и , а также О к л е н д и К э м п б е л л ) нужно с ч и т а т ь н е з а в и с и м ы м и з о о г е о г р а -фическими п р о в и н ц и я м и , что х о р о ш о с о в п а д а е т с м н е н и е м а в т о р о в в ы ш е указанной р а б о т ы . Г р у п п и р о в к а р а й о н о в в случае обеих р а с с м а т р и в а е м ы х групп ж и в о т н ы х является а н а л о г и ч н о й , что. в с в о ю очередь, о т л и ч а е т с я о т предложения Нокса и Л о у р и . С о м н и -тельным кажется также подчеркивание а в т о р а м и того ф а к т а , что в случае Polychaeta м а г е л л а н с к а я провинция не о т д е л я е т с я о т ч е т л и в о о т о с т а л ь н ы х антарктических провинций. П о м н е н и ю а в т о р а н а с т о я щ е й с т а т ь и н е о б х о д и м о п р и н я т ь с л е д у ю щ е е разделение, о д и н а к о в о е и я обеих i p \ i i n бентоса (рис. 5): Провинция восточной А н т а р к ш д ы П р о в и н ц и я з а п а д н о й А н т а р к т и д ы (Дуга С к о т и я с А н т а р к т и ч е с к и м п о л у о с т р о в о м ) М а г е л л а н с к а я провинция О с т р о в а Кергелен и Х ё р д О с т р о в М а р и о н О с т р о в а М а к к у о р и О с т р о в а О к л е н д и К э м п б е л л . Разделение восточной и з а п а д н о й А н т а р к т и д ы , как о т д е л ь н ы х зоогеографических провинции, в соответствии с п р и н я т ы м и п р и н ц и п а м и а н а л и з а д а н н ы х , является более о б о с н о -в а н н ы м , чем объединение их -в одну о б л а с т ь .7. Streszczenie
W y k o r z y s t u j ą c tabele podobieństw K n o x a i L o w r y ' e g o (1977) o p r a c o w a n e na podstawie rozmieszczenia antarktycznych Polychaeta i Amphipoda, przedstawiono propozycję matematycz-nego g r u p o w a n i a rejonów szelfu antarktyczmatematycz-nego. P o s ł u g u j ą c się metodą opisaną przez F l o r k a i innych (1951) ułożono n a j k r ó t s z e dendryty rejonów o r a z d o k o n a n o ich n a t u r a l n e g o podziału (rys. 1, 2, 3, 4).
N a j m o c n i e j s z e podziały obu d e n d r y t ó w potwierdzają i d o b r z e uzasadniają tezę K n o x a i L o w r y ' e g o (1977) o j e d n o r o d n o ś c i fauny antarktycznych Polychaeta i o d u ż y m zróżnicowaniu fauny Amphipoda. Z analizy o b u d e n d r y t ó w wynika, że wyspy s u b a n t a r k t y c z n e (Kerguelen i Heard, M a r i o n , M a c q u a r i e o r a z Auckland i Campbell) należy t r a k t o w a ć j a k o niezależne obszary zoogeograficzne, co jest zgodne z z a p a t r y w a n i e m a u t o r ó w oryginalnej pracy. G r u p o w a -nie rejonów w p r z y p a d k u obu r o z p a t r y w a n y c h g r u p zwierzęcych jest p o d o b n e , co z kolei
3 1 6 Jacek Siciński różni się od propozycji K n o x a i Lowry'ego. D y s k u s y j n y m wydaje się podkreślenie tych a u t o r ó w , iż w p r z y p a d k u Polychaeta o b s z a r magellański nie jest zbyt p r z e k o n y w u j ą c o oddzielony od o b s z a r u antarktycznego.
Z d a n i e m a u t o r a niniejszych uwag należy przyjąć następujący podział, j e d n a k o w y dla o b u g r u p bentosu (rys. 5):
O b s z a r A n t a r k t y d y W s c h o d n i e j
O b s z a r A n t a r k t y d y Z a c h o d n i e j (Łuk Scotia z Półwyspem Antarktycznym) O b s z a r magellański
Wyspy Kerguelen i H e a r d Wyspa M a r i o n
Wyspy M a c q u a r i e
Wyspy Auckland i Campbell.
Rozdzielenie A n t a r k t y d y Z a c h o d n i e j i W s c h o d n i e j j a k o o s o b n y c h o b s z a r ó w zoogeograficznych jest, w myśl przyjętych założeń analizy danych, bardziej u z a s a d n i o n e niż łączenie ich w j e d e n
obszar.
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2. A v e r i n c e v V. G. 1972 — D o n n y j e m n o g o s c e t i n k o v y j e cervi Errantia Antarktiki i Sub-a n t Sub-a r k t i k i p o m Sub-a t e r i Sub-a ł Sub-a m Sovetskoj A n t Sub-a r k t i ć e s k o j Ekspedicii — IssledovSub-anijSub-a F Sub-a u n y Morej,
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