Marine Biology 14, I--9 (1972) by Sprlng~r-Verlag 1972

The ecological principle of evolutionary reconstruction as illustrated by marine

A. N. Gor~n~ov and N. L. TZV~TKOVX

Zoological Institute, Academy of Sciences of the USSR; I~ningr~:l, USSI~

Almtraet tion and ecology of modern with fossil remains Analysis of the evolution, distribution and ecology of of similar taxonomio categories and the general marine prosobranchs of the genera and Z4ttor/na characteristics of deposits of corresponding geological and amphipods of the genera Anlsogammarus and Gararnarus periods of the past. They provide, with a reasonable demonstrates the possibilities of ecological and palaeoecolog- degree of certaSnty, a pichLre of climatic changes of ioal methods in composing evolutionary reconstructions. A comparative study of historical climate ch~n~ and of the globe during the known geological epochs palaeogeography in areas inhabir by certain taxonomic (Kn~,su,,,oP~ovIcr~, t932; B~mG, t947; Bgv~s, t952; groups, coupled with information on the distribution and Rvcm_~, t955; Sc~w~RZ~A(:~, t955; G~KK~, t957; ecology of species belonging to these groups, allows us to MA~OV, t960; SINXTZ~, i965, t966; etc.). Palace- determine the time and locality of the origin of diverse bio- ~hraphical groups of species and to trace the routes of their geographical information from corresponding regions er distribution, even in those organisms which have no is essential in order to appreciate the pat'verns and fossil remains. Species dwelling under conditions which cor- rules governing the distribution of organisms in the respond historically to the most ancient climate of their sald regions. dwelling area prove to be more primitive f,h~n species dwelling under newly-formed climatic oonditSons. For instance, sub- Sometimes it is possible to reconstruct the palace- tropical species of the genera under consideration, in the North- geographical picture of the pa~ by analysis of the western parts of the Pacific and Atlantic Oceans, have proved geographical distribution of modem species. The to be more ancient and primitive than species inhabiting the application of the biogcographical principle of the upper boreal Pacific and Atlantic waters and the Arotic Ocean. Therefore, the palaeoocological analysis of the historical de- geological history of the Quaternary period (I~vD- velopment of faunas from different regions of the globe, com- B~m~, t955, i965) may be cited as an example of bined with the application of the morphological principle, can coordinated analysis of biogeographical and palace- significantly contr~ute to a more detailed and precise under- geographical data. sf~mding of the processes and/xends of evolu~on which com- pose the phylogenetio schemes of the taxonomic groups under dJscnssion. Material and method Introduction The application of the pala~oeeological method is In order to understand the faunal and floral based on the closest dependence of development of formations in different regions of the globe, the re- modem flora and fauna upon the his~ry of climatic cons~t'uction of evolutionary schemes reflecting both changes in various parts of the globe. The said depend- the phylogenetie relations among organisms and the ence is determined by a decisive influence of physico- time and locality of the origin of diverse taxonomic chemical factors upon the process of speciation and categories is essential. the subsequent distribution of the species. ttowever, the majoldtTy of scientists assessing Therefore, by comparing ecological data (especially phylogenetic reconstructions -- especially in regard to on thermopathy) and data on the distribution of groups of organisms without fossils -- make use of modem species with information concerning the history the morphological method only; this enables species of climatic changes and palaeogeography in the dwell- to be categorized according to their degree of ~t,-ue~ural ing regions of the species considered, we can evaluate resemblance and the progressiveness of some of their the ecological situation and, hence, the locality and peculiarities, but it produces no clues as to time and time of origin of those species, and we can tzace the place of the origin of the species. probable ranges of their distributions in the past and Although in no way depreeiaffng the above- the trends of their evolution. mentioned morphological principle for studying evolu- It seems obvious that species dwelling under the tion and phylogeny of organisms, we consider it histqrieaJ]y most ancient olin:ratio conditions must be highly desirable to apply, in addition, ecological more primitive within their genus, and retain plesio- and pala6oeeological information. The data available morpheus (terminology of Hmv~iG, t950) peculiarities, at present are based on the comparison of the distribu- while species whose distribution is based on newly- 1 ]~arlu6 Biology, VoL 14 2 A.N. GOLI:KOVand N. L. Tzvm'~ovA: Evolutionary reconstruction Mar. Biol. formed climatic conditions are phylogeneticaUy young- In the analysis of the evolution of species belonging er, and e~hibit apomorphons peculiarities. This to the genera Gammarus and Anisogammarus, because assumption is confirmed by comparative-morphologieal of paucity of fossil rem~ina, the comparative-mor- and palaeontological data, and may be considered in phological principle of comparing plesiomorphons and the analysis of taxonomic categories of a higher rank. apemorphons peeuliarities of different species has been Particularly striking and convincing evidence, chiefly used as control. Additional criteria for assessing which illustrates the application of the ecologieM time and locality of the origin of a species and of the principle, is received when the history of climatic corresponding climate were provided by minimal changes in cold and temperate zones of the Northern intraspeeifie variability, corresponding to the ecological hemisphere during the Tertiary and Quaternary environment of the origin and primary adaptation periods is compared with the evolution of species (GoTx~ov, t963). dwelling in the same zones. In Neptunea species, we considered the develop- Geological and palaeoecologieal data provide ment of the axial sculpture; it depends upon tempo- evidence of a constant climatic cooling in the Northern rary decreases in growth rate during periods of in- Hemisphere, which has occurred over a relatively creased environment~d variability. The axial sculpture brief period of geological time. of species inhabiting comparatively warm waters and The origin, formation and development of the fauna that of intraspeeifie forms is weakly developed, and flora, specific for temperate and cold climatic while that of cold-water species (with contracted conditions, occurred under the impact of the said spawning period) is highly developed. While establishing phyletic correlations between coollng, which was intermit-ted by short pulsations of temporary warming in several zones. species, we made considerable use of morphological peculiarities of the various species, with due con- Simultaneously, the fauna of temperate latitudes sideraNon to the fact that the morphological principle, may have been flmdamentally formed during the coupled with the ecological principle, enables the course of the Tert~ry period under the conditions construction of the most correct temporal and spatial of the gradual establishment of a temperate climate, evolutionary schemes. while the fauna of the Arctic area, dwelling under lower temperature conditions, and even at temperatures Results below zero, may have developed in the Quarternary The clin~te of the area of present temperate and period at the time of glaciation in high latitudes of the cold latitudes of the Northern Hemisphere in the Northern Hemisphere. early Paleogene period was relatively stable -- similar A review of the system of gastropods of the genus to that of the modern subtropics. Neptunea BoL~ (Go~ov, t963, t964) and amphi- Apparently, under the impact of the first stages pods of the genera Gammarus s.l. (sea- and brackish- of climatic cooling in the late Eocene, the genera water species) and Anisogammarus Dm~z~AvlN Neptunea and Anisogammarus evolved in compara- (TzVETKOVA, t969 ; and in press) 1, has been completed tively cool subtropic waters from ancestral forms in the by the present authors. A thorough analysis of the area of present Northern Japan. The genus Gammarus morphology, ecology and distribution of the species evolved in the basin of the Atlantic Ocean -- the composing these genera, which inhabit mainly the Tethys Sea. Evidence of this process is provided (t) boreal and Arctic sca~, enables the comparison of the by the distribution of modern, most primitive species, application of morphological and pala~ontologieal which are Nmilax to the initial forms; these live under principles on the one hand and the application of conditions Mmilar to their ancestors. (2) The discovery ecological and palacoeeological principles on the other of the first fossil residues of the genus Neptunea in hand, with a view to revising the conception of the the Upper Eocene and the Oligocene deposits of the evolutionary development of both of these genera. Japan Islands (N. altispirata, N. sitakaraen._cis), and Neptunea species are particularly abundant in the of the genus Gammarus in the lower Oligocene deposits fossil deposits of the Tertiary and Quarternary periods; of the Paris basin (G. a]zaticus). this affords an opportunitT of testing the correctness The hypothesis that the locality and time of origin of the application of the palaeoecological method of the genus Anisogammarus resembles those of both by comparative-morphological and by palaeon- Neptunea is supported by comparative-morphological tological evidence. and palaeoecological analyses of the former's evolution and distribution, which have been influenced by 1 The genus Anisoyammarus consist~ of 3 subgenora: A. ~imilarly changing conditions and which proceeded (An~sogammarus) Dm~z~Av~, A. (Eoffammarus) B]:Rs,I.m.~, and A. (Spinulogammarus) Tzvm'aovx, subgenus nov.; the in a way similar to those of the Neptunea. latter includes 7 species with spines both on the urosome and The relatively constant temperature conditions the metasome: A. ?'esovns~, A. ~pa~k/i, A. vvhot~as~, A. which prevailed in the Northern part of the Pacific oregonen~, A. xubcar/natu~, A. atchens~ and, probably, A. and Atlantic Oceans during the Paleogene period, must armanda~; the type-species of the subgenus is Gammarus ochegens/s Bm~rr, t851. have allowed the primitive species of the genera under Vol. 14, .No. 1, 1972 A.N. GOLIXOVand N. L. Tzvm'~ovA: Evolutionary ro(xmstametion 3

study to disperse widely towards the North. At the A.(Sp/nulo- A(An/so- same tfime, or at the very beginning of the Neogene A. (Eogammarus) gammacus) _qc~r~ period, species of the said genera, dwelling in relatively warm waters, may have penetrated to the Pacific (Neptunea and Anisogammarus) and Atlantic (Gara- marus) coasts of North America. The probability of interchange of fauni,~tie ele- ments which dwelt on the coasts of Japan with those of the Pacific Ocean on the coasts of North America in the 1)aleogene and early Ncogene periods,

u,1

o ,.-,.,-, u o :~'~ ~,--~ I ,!

Fig. 2. Evolution of species of the genus Anisoyammarus D~mz- ~AvI~. Symbols as inlegend to Fig. I , I / t/ / ikus e . z

t[I N 5ito.t~r~'-ensls Pe:, G(Laguno- G Marino- redo]g~-nm~-us)(Gzmm.) g~*nmarus N alffs~'r'~ta

Bruclarkla Nept~nea o . w ..... o ~, ~.s'~.~ ~-.~.~.~ u "1- - ~ s ~,e. ~ o J/' Fig. I. Evolution of species of the genus Neptunea Bor~vm~. fossil species; ..... phyletic relations between species; -- duration of existence of species

I i ~alsaticus ,?/, I ~I is affirmed by many authors (Smaa~, 1904, i919; i::m~ / z / _.'-; r I z/" I I Palaeogammarus baltJcus \ /,, I . ! -- G~T and GALE, i931; KmSTO~OVlT(m, ~932; ete.). i ,Z," G(GarnmJ b'farJnog~rnm. ..-"~ ~Pa/aeon'amrnaru~ The first modern species evolved in subtTopical / / .~-- z~mblenSiS o ',jJ" waters in the early Miocene; at present they dwell G (Pephredo) /*" ]~."~- .... ~mder analogous conditions [Neptunea intersculpta, Gammarus ",L/" f" N. /ukueae, Anisogammaras (Eogammarus) turgi- manus, A. (Spinulogammarus) annandalei, Gammarus Praeg~mmarus (Pephredo?) ~]. These species axe closely I related to the fossil ances~M forms of the correspond- ing genera, and may have evolved directly from them Fig. 3. Evolution of species of the genus Gammaruz FAnR!Cavs (Figs. 1, 2, and 3). s.1. Symbols as in legend to Fig. 1 The Pacific species originaf~d in waters washing the Miocene coastline in the region of the present Northern Japanese Islands (Fig. 4). The discovery in~raspeeific variability of species which are sub- of the first fossils of Neptunea inters@ in this Vropical by origin--provides evidence for the validity region -- as well as the palaeoeeological climate in of this hypothesis. this area during the early Miocene, which corresponds The Lnsitanian-Mediterranean species Gammaru~ to the present climatic conditions with minlm'u~n. (Pephredo?) /ocu~ta may have originated in the 1" 4 A.N. Golaxov and N. L. Tav~rr~ovx: Evolutionary roco~otion Mar. Biol. remnants of the Tethys Sea. Approximately at the by the remarkably primitive struct-ure of modem same time, and under similar conditions, the most boreal species dwelling both along the Asian and primitive represenf~tives of the genus Marinogam- American coasts studied by the present authors. rnarus, at present inhabiting the Northern Atlantic If we assume that these species have been formed Ooean (M. marinus, M. olivii), may have evolved. in the southern part of that area, in waters with A Vypical example of the application of the su~ciently high s~lmmer temperature, the possibility ecological principle in evolutionary reconstruction is of their spreaAing into the Bering Sea becomes highly the palaeoecologieal analysis of origin and distribution improbable as, in this region, even the summer of widely spread boreal Pacific species. These species temperatures do not rise over 6 ~ to 8 ~ ; such temper- may have evolved in the middle Miocene in the some- ature conditions must have prevented the breeding what oool waters of the coasts of Beringia, from an- of organisms of subtropical and low boreal origin, as eestrM forms which had widely spread. The borders their breeding temperature is firmly fixed (0~o~, between climatic zones were only slight at that t920; Rly~vss~6~, t927, t929; HlrI~aI~S, t947; period; this fact made it possible for the species which K~wl~, ~963, 1970; and others); their breeding originated in that area [Neptunea lyrata, Aniso- temperatures were probably fixed during the process gammarus ( Anisogammarus ) ~getten~is, A. ( Eogam- of species formation. It seems rather unreasonable to marus) locustoi&s, A. (Eogammarus) makarovi] to assume that the widciy-dis~ributed boreal species of spread far to the South along the coasts of the Asian the Pacific Ocean may have evolved in a more recent and American continents. geological period, as even in the late Miocene there The increased cooling which ensued, an4 the existed already firmly fixed fanni~tio provinces, establishment of sharp border-lines between the resulting from the establishment of sharp border- temperature regime of the high-boreal and the low- lines between climatic zones, which would have boreal Pacific waters, forced these species in the prevented further distribution of the species which southern part of the area to migrate to greater water evolved under the given hydrological conditions of a depths (Ne~unea lyrata) or to shift their breeding eerfadn province or climatic zone. Later, widely boreal period to a cooler time of year. Such space-time species of the Asian coasts [Anisogammarus (Eogam- relationships of widely spread boreal Pacific species rnarus) tiushovi, A. (Eogammarus) kygi, A. ( Spinulo- is based on the analysis of palacoecologieal data, and gammaru~) stxtzskii] evolved directly from species confirmed (t) by the discovery of the first fossil widely distributed on the coasts of both continents, residues of N. lyrata in the middle Miocene deposits or from allied ancestral forms on the coast~ of Kam- of Kamchatka, Southern Alaska and Oregon, and (2) chatka. The fact that these coastal species do not

80

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60

4O 1-." ' " ' !.

90 60 30 0 30 60 90 120 1.50 180 150 120 90

Fig. 4. CenL-rm of origin (cirolos) and dis~ou~ional paths (arrows) of different biogoographical groups. Species of genera .~e~u~, Ani.8o~mmrt~, 6Mmmr~ and ~na. I: Paoiiie Asiatio subLTopical; II: Pacific widely distributed boreal; III: Pacific Asiatio low boreal; IV: Pacifio Asiatic widely ~butod and high boreal; V: Pacific American widely boroM; VI: Pa~ifio Am~ri~n low boreal; VII: bor~aretio; VIII." Okho~sk high boreal; IX: Atlantio high boreal; X: Mediterranean- L~mit~lio sub~opicM; XI: Atlantic Ame*ican low bol~l; XlI: Celtic low boreM; XlII: European widely boreal; XIV: Arotio. : contemporary paths;------: omcient lmt~a Vol. 14, 2;o. 1, 1972 A.N. GOnIKOVand N. L. Tzw'r~ova: Evolutionary reoonstruction 5

dwell off the American coast may be a result of the ing in the area of present Northern Japan; at this distwibution barrier constituted by the great depths time, sharply defined borders already existed between which had alreaAy been formed by this time in the the low-boreal and high-boreal waters. These shallow- southern part of the Bering Sea. water species, dwelling in well-warmed sea areas, Under the influence of subsequent, long-term, prefer temperature conditions which correspond thermal pulsations in the late Miocene, which resulted approximately to those existing in the whole aquatoria in the formation of fixed borders between climatic of the lower-boreal waters at that period. zones in the waters washing the Asian continent in Somewhat later, Neptunea cumingii, subtropical the region of ]~mchatka and Northern Sakhalin, in origin, may have evolved in more southern areas; the most erythermal high boreal species [Neptunea it has spread exclusively throughout geologically pribiloffen.sis, Anisogammarus ( Eogammarus ) tiushovi, younger Northern Chinese seas and in the Japanese A. (Eogammarus) /cygi] evolved from widely distrib- Sea. In the middle of the Plioeene, approximately in uted boreal forms or from common ancestors. This the area of present Sakhalin (judging by palaeoecolo- hypothesis is supported by the conformity of the gical information and the thermopathy of modern palaeoecological conditions in the late Miocene in species), another group of the low-boreal species, this region, with the breeding temperature and the distributed in the cooler waters, may have evolved: conditions of minimum variabili~r of the species Neptune.a constricta, N. polycostata, N. t u,bercuYx~. concerned reflecVing the conditions of their primary Approximately at the same time, species of high- adaptation; additional evidence in favour of this boreal origin [Anisogammarus ( Spinulogammaru.s) hypothesis is provided by the fact that fossil residues spasskii, A. (Eogammarus) barbatus], dwelling in of N. pr/b//offengs have been found in the upper comparatively warm waters, formed on the coasts of Miocene deposits of Northern Sakhalin and Kam- Kamchatka. They spread southwards along the Asian chatka. The morphological analysis of the phyletie coast up to the Southern Kuril Islands and Southern correlations of these species leads to the same con- Sakhalin; on the coasts of America, the Oregon species clusions. A nisogammarus ( Eogammarus ) ramellus, A. ( Eogam- It is highly probable that, in the late Miocene, a marus) con/ervicolus and A. (Spinulogammarus) brief lowering of the Bering platform may have occur- oregonens/s evolved. red, which offered the firs~ opportunity for the sub- Both the first and the second group of species littoral species Neptunea lyrata and N. pribiloffensis must have originated from widely distributed Pacific to penetrate into the Northern Atlantic Ocean. An species or from descendant forms inhabiting the greater analysis of the history of the formation of the genera part of the present temperate Pacific waters up to of the bivalve molluscs Mya, Macoma and some other the middle Miocene period; they evolved after sharp organisms, leads us to assume that the Bering Strait borders became established between climate zones and was formed during the late Miocene period, and that faunistie provinces. the most eurybiont elements of the boreal Pacific Later, but apparently before the period when fauna may have migrated to the Northern Atlantic permanent connections between the Pacific Ocean Ocean during the same period (MAc~mL, 1965; Cox,, and the Polar Basin were established (but directly 1969; and others). However, migration of boreal after a marked cooling had occurred), the high- Pacific species in the late Miocene to the coasts of boreal species (Neptunea vinosa, iV. Iaticostata, Central Europe and their giving rise to boreal Atlantic ~Y. in.sulariz , N. oncoda, A nisogammarus ( Eogammavws) species seems highly improbable, as subtropical schmidti and A. (Spinulogammavu.s) suScarinatus on climatic conditions predominaf:ed, to judge from the the coasts of Kamchatka, and Neptunea aminata, Lnsitanian-Mediterranean characteristics of the fossil N. smirnia, Anisogammarus (Anisogammavu.s) fauna of these regions. Apparently, the process of ma~initiei and A. ( Spinulogammamas ) atchensis on the speciation and the spreading of boreal species in the coasts of the Aleutian Islands and of Alaska) may Atlantie Ocean must have occurred later or in the have evolved, judging by their present-day distribu- second part of the Pliocene period, but the genetic tion. material for the formation of these species may have The phyletie relationships of these species are been supplied by popu]atious of later Miocene emi- revealed in their evolution. They have been evaluaf~l grants from the :Pacific Ocean, which spent the warm by means of pala~oecological analysis of the succes- period in higher latitudes. The genus Anisogammaru8 sion of origin and distribution and on the basis of may not have mi~ated to the North Atlantic Ocean; comparative-morphological information. For instance, these forms are fifily adapted to the littoral zone. Neptunea smirnia may have evolved from its mor- The first lower-boreal species [Neptunea arthritica, phologial relative N. ]u~aeae, which mi~ated with the N. bulbacea, Anisogammaru~ (Spinulogammar~s) waters of the Kjuro-Shive to the coasts of America in jesoensis and A. (Eogammarus) poss]eticus] formed the first part of the Miocene. The cooling in the northern in the late Miocene or at the very beginning of the part of the Pacific Ocean, which occurred in the late Pliocene, during the next pulsation of climatic warm. Miocene and the Pliocene, retorted in the formation 6 A.N. GonI~OVand N. L. Tzv~r~ovA: Evolutionary reconstruction Mar. Biol.

of N. smirn/a, and in the extinction of descendant genus Gazamarus. The first representatives of this forms of N. ]ukueae in the intervening areas. sub-genus evolved during the second part of the The submergence of the Bering-Chukotsk platform Pliocene, from the most ancient of the present-living joined together with water masses of the Pacific species of Gammarus, i.e., the Lusitanian-Mediter- Ocean and the Polar Basin. Further cooling of the ranean Gammarus ( Pephredo ?) locusta. northern part of the Bering Sea facilitated the forma- The brackish-water living, comparatively thermo- tion of the boreal-arctic species Ne:ptunea beringiana, phile, species Gam~arus (Lagunogammarus) salinus N. ventric~a and N. communis. These species evolved may have originated first. The brackish-water species from Neptunea lyrata or from related, now-extinct G. (Lagunogammarue) zaddachi, which has spread forms. On the basis of thermopathy and the present- somewhat wider than the former species, but is less day distribution of N. ber/ng/ana (North-west to the thermophilic, presumably evolved later from this Island of Bennet, North-east to the Island of Victoria), species or from common ancestors. this species must have evolved in the region of Western In the late Pliocene, under sharply changing Alaska and the Pribfloff Islands; in these regions, hydrological conditions, the eurybiont species Gam- fossil residues of N. beringiana have been found in maru~ (Lagunogammar~e) oceanicus may have Plioeene deposits. Neplunea ventricosa and N. com- evolved; this species has now spread far to the North. munis, which are widely distributed in the Arctic Appro~dmately at the same time, or somewhat and high boreal Pacific waters, evolved one after the earlier, the eurybiont brackish-water boreal species of other (at first N. ven~a) in the northeastern area another very ancient, chiefly fresh-water living sub- of the Bering Sea, or in the southern part of the genus, Gammarus (Gammarus) duebeni may have Chukotsky Sea. Species of the genus Anisogammarus evolved. (apparently because of their genotypical adaptation to the littoral zone) may not have given rise to any The evolution of the genus Marinogammarus, boreal-arctic forms. influenced by a similarly changing environment, is The cooling of the North Atlantic Ocean, which analogous to that of the genus Gammarue. The Celtic began in the middle Pliocene period and gradually species M. pirloti and M. stoerensis were presumably increased, resulted in the formation of boreal water- the first to evolve within this genus from the Lusi- masses, and formed a corresponding fauna in this tanian-Mediterranean Marinogammarus marinus, ocean. Apparently, parallel to the formation of the while in the late Pliocene period, in cooler waters, upper boreal water masses off the coasts of America, the lower boreal M. obtueatus origina~xt, followed by Neptunea ~ -- morphologically related to the less eurybiontie high-boreal M. finmarchicus. N. pr/b//o~ens,'z -- may have evolved from descendants The arctic species obviously formed in Arctic of the latter, who had penetrated into the Atlantic waters masses, which were formed by Pleistocene coastal waters in the late Miocene (or, less probably, glaciation in the higher latitudes of the Northern in the second part of the Pliocene, after the secondary Hemisphere. Gammarus (Lagunogamrnarus) screen, migration of this species into the Atlantic Ocean). distributed throughout a vast arctic-boreal ares, and The variability, ecology and present-day distribu- continuously adapted to the littoral zone, may have tion of Neptunea destm_rga provides evidence of the area been the first species to originate from G. (Laguno and time of its origin. The mlg'ration of N. des/~zta gammarus) oceanicus or from related ancestors. to the coasts of Europe during the period of pro- Later, apparently at the height of glaciation, G. nounced climatic changes, which occurred along the (Laffunogammarus) willdtzl~ii must have evolved; this coasts of this continent in the ]ate Pliocene, resulted species had begun to dwell under the lower surface in the formation of N. ant/q~a from this species. of the drifting ice cover and had inhabited the central Judging by the ecological peculiarities and the time parts of the Polar Basin, and might have penetrated and place of the discovery of the first fossil residues to the high boreal waters of the Pacific Ocean during of this species, N. ant/q~za must have originated in the the period of intraglacial sea transgression. The aquatorium of present-day Southern England. arctic Nep/~nea densetirata, known in its fossil form Ecological information and the distribution of from the glacial deposits of Western and North- modern species of the genus Gammarus s.l., supported western Norway and, on the basis of ecological and by comparative-morphological analysis of the phyletie morphological evidence, one of the recently formed correlations between evolubionary advanced and species of the genus Neptunea, presumably originated primitive species, show a definite similarity between from N. communis in the Pleistocene period, during the locahty and period of the formation of boreal the period of increasing glaciation. species of this genus and those of Atlantic species Great and vigorous geological events in the of the genus Neptunea. However, boreal conditions in western part of the Okhotsk Sea, and the establish- the Northern Atlantic Ocean resulted in the formation ment of glacial conditions there in the second part of of an independent sub-genus, Ix~Funogammam~s SKE'r the Pleistocene resulted in a powerful outbreak of (part2m) (S~T, i97f), during the evolution of the Sl:mCiation in this part of the Pacific aquatorium. Some Vot. 14, No. 1, 1972 A.N. Go[axov and N. L. T~-m~ovx: Evolutionary reconstruction 7 of the glacial Okhotsk Sea species evolved at that The genus L/ttor/na seems likely to have originated time from the genetic stock of relatively ancient, in the somewhat cooled subtropical waters between lower boreal and subtropical species (Neptunea the Eocene and the Oligocene off the Asian coasts, varici/era, N. IameY~a), while others derived from were Japan is presently situated. The most ancient of widely distributed boreal and upper-boreal Pacific modern species of this genus, ZAttor/na brevicuIa, species [ Anisogammarus ( Eogammarus ) aeztuariorum which is, by reason of its thermopathy, subtropical sp. nov., A. (Eogammarus) hirsutimanus, A. (Spi- and, therefore, subtropical in origin, may have ori- nulogammarus) ochotensis]. The single exclusively ginated in the early Miocene in comparatively cooled pacific, glacial-Okhotsk Sea species of the genus subtropic coastal Asian waters. This species has the Gammarus, G. ( Lagunogarnmarus ) Icamt8chaticus, greatest affinity (within the genus) to representatives derived from G. (Lagunogammarus) wilkitzkii, which of the more ancient genera of the family, inhabiting sub- penetrated to the Okhotsk Sea from the Arctic during tropical and tropical waters. L. brevicula's ancestors, the late Pleistocene. and probably L. brevicula it, ll, have spread widely throughout the northern part of the Pacific Ocean. After the separation of the low-boreal water mass off the coasts of Asia in the second part of the Miocene, Littorina mandshurica may have derived from these forms; the ecologic peculiarities of L. rnandshurica

u correspond to the conditions established at that time 2 in the lower-boreal biogeographical province. Some- what earlier, the temperate eurythermal species L. kur//a, off the coasts of Beringia, was derived from 0 ancestors common to L. brev/cu/a and probably com- mon to L. mandshurica; the genotypical peculiarities 0- and primary adaptation conditions afforded this species an opportunity to spread throughout boreal

o Pacific waters. K /I.. Simultaneously, and in the same area as L/ttor/na / /r another widely distribut~t Pacific boreal

o species, L. (Algaroda) 8qualida, may -- as a result of \\/ increased cooling in the northern part of the Pacific \ Ocean-- have originated from other, apparently more ancient forms, which gave rise to the sub-genus Al- garoda, and sufficiently spread until the middle 0 Miocene. The laf~ Miocene cooling may have caused the forma-

U2 tion off the coasts of Alaska of the species L/trOt/ha s/tchana (probably directly from L. kur//a), which has mainly spread throughout American coastal waters. Probably at the same time, L/trot/ha kur//a, L. sitehana and L. squa//da penetrated along the north- Fig. 5. Hypothetical scheme of evolution of the genus L/trot/ha ern coasts of America to the Northern Atlantic Ocean. lVgavssAc. Symbols as in legend to Fig. l Already in the Pliocene period in the region of the Aleutian Islands, the high-boreal species of L/ttorina a/cut,a, morphologically allied with L. brevicula, may have derived from L. brev/cv2a or from common We offer a conjectttral scheme of the evolution of ancestors. the genus L/trot/ha as an additional illustration of the In the second part of the Pliocene period, the use of ecological and palaeoecological information establishment of boreal climatic conditions in the for the reconstruction of temporal-spatial evolutionary Northern Atlantic Ocean and the migration of the schemes, based on a detailed analysis of comparative- descendants of species which had already penetrated morphological and palaeontological data. The majority to the coasts of Europe from the Pacific Ocean, may of species of this genus (Fig. 5) dwell in the littoral have resulted in the formation of boreal Atlantic zone, and their origin and development can serve as species --/Attorina obtusata from the descendants of a good illustration of convergency in the direction of L. kurila, L. saxatilis from the descendants of L. evolution and distribution, together with those of the s/tchana and L. l/ttorea from the descendants of littoral genera Anisogammarus and Gammaru~. L. squalida, respectively. 8 A.N. Gorm~ov and 1~. L. T~vwr~ovx: Evolutionary rooonstruction Mar. Biol.

~n analysed represenf~ part of a more general process in A dist~ct convergencyin the evolution of the genera the formation and development of the whole fauna of under consideration can be seen -- the biogcogra- the areas of cold and temperate waters of the Northern phical groups of species were formed at similar local- Hemisphere considered. ities and at the same periods. The formation and distribution of the genera Gammaru8 and Anise. SliT/Ira 1~i~r gammarus illust-rate parallel evolutionary develop- ment with homologies1 lines (VAv~ov, 1922; TZV]~- 1. We suggest the application of an ecological KOVA, i969) and with ~imilar ecological niches occu- method of constructing tSme-space schemes of evolu- pied by bionomically analogous species. tionary trends. This method is based on the principle of close dependence of the distributional range and the The boreal waters of the Northern Atlantic Ocean dwelling conditions of modern species upon (i) climate are inhabited by a fauna which is less abundant than (environment) effective during their formation; (2) that of the boreal waters of the northern part of the primary aclapt~tion; (3) subsequent distribution as Pacific Ocean; this can be easily a~cotmted for, since influenced by historical changes of the climate in the boreal conditions were established first in the latter dwelling region. aquatorinm and then in the former -- consequently, 2. Application of the ecological method is fllus- the fauna within the former aqnatorium developed t-rated by the analysis of the evolutionary development during a shorter period of time. Moreover, the shorter of gastropods of the genera Neptunea and L/ttor/na, and meridional extent of an aquatorinm with boreal condi- amphipods of the genera Anisogammarus and Gamma- tions such as the Atlantic Ocean, as compared to the rue, distributed throughout the cold and temperate Pacific Ocean, may have had some influence. waters of the Northern Hemisphere. The study of the process of formation of the genera 3. The validity of the ecological principle of under investigation provides evidence of the fact that evolutionary reconstrnetions gains support from com- vh-tually all modern species of these genera ori~naf~t parative-morphological and palacontological informa- from the former geological epochs at the time of vigor- tion, and from the degree of intraspecific variability, ous geological shocks and sharp hydrological condition which proves to be mlnimal under conditions approach- changes in the greater part of the aquatorinm in which ing those existing at the time of the formation and the species under consideration dwell. prlmA.ry adaptation of the species considered. The process of species formation was followed by 4. Species ~ dwelling under conditions corre- a pronounced increase in variability of the paternal sponding to their most ancient climatic environment species, by greatly increased selection, which influenced are more pMmltive than those inhabiting areas with, the production of formative processes of a series of historically, more recently formed climatic conditions. species at the time of environmental pulsation (the In the northern parts of the Pacific and Atlantic species are partly preserved in fossil remains), and by Oceans and in the Polar Basra, species of the genera an increase in intraspecific variability of ancestral under study, subtropical by origin, prove to be more forms. ancient and primitive than those inhabiting the high- A wide intraspecifie variability at the edges of boreal and Arctic waters. these areas can be observed even among modern spe- 5. Convergency and parallelism in the evolutionary cies (Go,Key, 1960, i968), but the comparative sta- development of diverse groups, which occur bility of climatic conditions of the Holocene hinders under similarly changing environmental conditions, the formation of new species due to specific homeo- and which manifest themselves in the s~milarity of static reactions and genotypical conditioning in regard time and place of the formation of analogons bio- to the faunal distribution ranges. geographical groups of species, lead us to assume that Similarity of time and place of formation and of the evolutionary trends of the genera analysed are time course of distribution of different animal groups, a part of the formation and development of the fauna conditioned by similarly changing environmental fac- of cold and temperate waters of the whole Northern tors, adds much to, and proves the correctness of, the Hemisphere. evolutionary reconstructions presented. This is true 6. The ecological principle combined with palace- for each of the genera under consideration. It justifies ecological data allows the reconstruction of time- the construction of time-spa~e schemes, also for groups space evolutionary schemes even for groups of or- of organisms without fossil remains. ganisms for which no fossil remains are available. Common climatic histories in the dwelling regions of highly dissimilar groups of organisms, which in Literature cited coinciding area~ required sdmilar environmental condi- B~RO, L. S.: Climate and life, [-In Russ.]. 356 pp. Moscow: tions and which have developed under the influence of Gcographgiz 1947. the same environmental factors, leads to the hypoth- BRVKS, K.: Climates of the past, [In Russ.]. 356 pp. Moscow: esis that the evolutionary scheme of the genera Izdatelstvo Inostr~nn~ja Litera~l"a 1952. Vol. 14, No. 1, 1972 A.N. Go~rKOV and N. L. Tzvm'Kovx: Evolutionary reconstruction 9

COAN, E.: Recognition of an Eastern Pacific Macoma in the RvcmeL L. B. : Climates of the past. [In Russ.]. Byull. geogr. coralline crag of England and its biogeographie significance. Inst. 87 (2), 106--119 (1955). Veliger 11 (3), 277--279 (1969). RW~ST~BM, S. : ~[ber die Thermopathie der Fort-pflanzung G~gz~m, g. F.: Introduction to palaeoecology, [In P~uss.]. und Entwicklung mariner Tiere in Beziehung zu ihrer 126 pp. Moscow: Gosgeoltechnizdat 1957. geographisehen Verbreitung. Bergens Mns. Arb. (naturvid.) GO~KOV, A. N. : The distribution and variability of Neptunea 2, t~67 (1997). despecta (~) as an indicator of the regime of the s~. -- Weitere Studien fiber die Temperaturanpassung der Fort- [In Russ.]. Zool. Zh. 80 (t0), 1485---1488 (1960). flanzung und Entwicldung mariner Tiere. Bergens Mns. -- Gastropods of the genus Neptunea BoLTtrtr. [In Russ.]. rb. (naturvid.) 10, 1--54 0929). Fauna SSSR 1, 1--217 (t963). SC~w~I~Z~ACH,M.: Das Klima der Vorzeit, [in Russ.]. 284 pp. -- Evolution of gastropods of, the genus Neptunea BoLwm~. Moscow: Izdatelstvo Inostrannaya IAter~tura 1955. In: Problems of theoretical and practical malacology, Sn~,l-za~, V. M. : Ancient climates of Eurasia, Part 1. Palaeo- [In Russ@ pp 109--t28. Moscow-LeningTad: Izd. Akade- gene and Neogene, [In Russ.]. 167 pp. Lenin~ad: mii Nauk SSSR 1964. Lenin~ad University 1965. -- Distribution and variability of long-lived benthic animals -- Ancient elimat~ of Eurasia, Part 2. Mesosoi, [In Russ.]. as indicators of eta'rents and hydrological conditions. 167 pp. Leningrad: Lenin~ad University 1966. Saxsia 34, 199--208 (1968). Sg~r, B. : Zar Systematik und Phylogenie der Gammarini GRn~T, U. S. and H. R. G~5~: Catalogue of the marine (Amphipoda). Bull. sei. Cons. Acad. Sci. Arts RSFY 16 Pliocene and Pleistocene of California and ad- (I--2), 6-7 (1971). jacent regions. Mere. S Diego Soc. nat. ]~st. 1, 1--1036 S~T~, J. P. : :Periodic migration between the Asiatic and (1931). American coasts of the Pacific Ocean. Am. J. Sci. 4 (7), I~E~VIO, W. : Grnndzfige einer Theorie der phylogenetischen 2t7--233 (1904). Systematik, 367 pp. Berlin: Deutscher Zentralverlag 1950. -- Climatic relations of the Tertiary and Quarternary faunas HvTc~s, L. W.: The bases for temperature zonation in of the Californian region. Prec. Calif. Acad. Sci. (Ser. 4) geographical distribution. Ecol. Monogr. 17, 325~335 9 (4), t23--173 (1919). (1947). KI~, O.: The effects of temperature and salinity on marine Tzvm,~ov*, N. L.: On the parallelism of evolution, distribu- and brackish water ~nimals. I. Temperature. 0ceanogr. tion and ecology of the genera Gammarv,s, Marinogam- mar. Biol. A. Rev. 1, 301--340 (1963). maru8 and Anisogammaru~ (Amphipoda, Gammaridae). -- Temperuture: animals--invertebrates. In: Marine ecology, In: Reports of the scientific session of the Zoological Insti- Vol. 1, Environmental factors, Pt. t. pp 407--5t4. Ed. by tute on results of researches in 1968. Theses of Reports. O. Knv~. London: Wiley t970. [In Russ.]. pp 4~5. Leningrad: izdatelstvo Nauka 1969, K~Isn~roesowc~, A. N. : Geological review of the Far East -- On the system of the genera Gammarus and Anisogam- countries, [In Russ.]. 332 pp. Leningrad-Moscow: Nautseh- maru~ and a new species of gammarids (Amphipoda, Gam- no-technitseheskoje geologo-razved, izd~t. 1932. maridae) from the north-western part oft~e Pacific Ocean. LL~DB~O, G. W.: The Quarternary period in the light of [In Russ.]. Trudp zoolog. Inst. Leningrad 51 (In press). biogcogruphical data, [In Russ.]. 335 pp. Moscow-Lenin- -- The amphipods of the gener~ Gammarus, Marinogammarus, grad: Izd. Akademii Nauk SSSR 1955. Anisogammarus and Mesogammarus (Amphipoda, Gamma- -- Important planetary fluctuations of sea-level and paleo- ridae) from north and far-eastern seas of USSR and neigh- geography in the Quaternary period. In: Principal prob- bouring re,ions. [In Russ.]. 422 pp. (UnpubLished manu- lems of study of the Quaternary period. VII. Congress script). of INQUA (USA), [In Russ.]. pp t35--142. Moscow: V*~mov, N. I.: The law of homologous series in variations. Nauka 1965. J. genet. 20 (1), 47---89 (1922). M~cNE~, F. S. : Evolution and distribution of the genus Mya, and tertiary migrations:of Mol]usca. Prof. Pap. U.S. First author's addre~: Dr. A. N. GoxIKOV geol. Sure. 488, 1---51 (1965). Zoological Institute M~.~ov, K. K.: Palaeogeography, [In Russ.]. 268 pp. Mos- Academy of Sciences of the USSI~ cow: Moscow University 1960. Universitetskaya nab., 1 ORTO~;, J. H. : Sea temperature, breeding and distribution in Lenln~ad B-164 marine animals. J. max. biol. Ass. U.K. 12, 339--366 (1920). USSR

Date of final manuscript acceptance: January 3, 1972. Communicated by M. E. V~OORADOV, Moscow

2 Ma~inoBiology, Vol. 14