Document rxZp7kX6arq90zGz2bYg0VaeV

1220 NATURE VOL. 22B DECEMBER 19 1970 egg per cob or water hole: if this were not the dm even extreme noHUhnwi ooukl not be favoured by selection. Heliothit moim to have this habit in nature11 in spite of a contrary impreesion given by Kirkpatrick". But . why, if the model is oorreot, are mote convincing examples of spite hard to And T First, I suggest, because all actions do ooet something. 8eoond, because an animal will not normally have any way of reoognizmg which other members of its species have less than average relationships. Memory, local odour, and nearness to place of birth may permit recognition of close relatives, but this leaves a remainder whose average relationship will be only very slightly lees (in large populations) than the total average. Moreover, with common patterns of dis- psrsal tho unreoogniasd individuals most likely to be enoountered are the ones likely to be most related. Third, because single populations that are so small in "effective !/ size" as to have 6< generally much different from zero must be in a precarious position already, and the selection i, of a gene causing spite can only hasten their extinction. ,} If, on the other hand, there is a composite population i made up of many such small precarious elements, either we must recognize a process of group selection in which those elements that have not yet been overwhelmed by selfish and spiteful mutations replace those that have, V or we must oonsider relationship against the background of the totgl population, as seems the nature] point of view if tho subpopulations are emitting and receiving migrants. Taken together these points suggest that my previous aooount is not seriously inaccurate for social behaviour in realistic circumstances. The point that has now been brought into focus, the adaptiveness of selfishness and spite in panmictic population!, suggests one reason why panmixia hardly oocurs. When It does ooour, the selection of selfish traits reduces mean fitness and the population is forced to retreat from its less favourable habitat*. If it remains panmictic the trend may continue and lead to extinction. If, on the other hand, the population breaks . into isolates as population declines, a breeding structure may be achieved in which further spread of selfishneea, and hence further decline, can be resisted. Imperial College Field Station, Silwood Park, Ascot , Berks. W. D. Hahtltoic Rtotlnd February 6; reYtoed JoJy It, ISIS. 1 Kunltton, W. !>., Amer. HaL, 17, SM (IMS). Hamilton, W. !>., J. Thaar. MU, 7.1 (1M4). 1 Hamilton. W. D., in tfan and Mmtt: ComparmHat Sactal Bahmatam (Pm. 8mithaoniait ImHMuii Third Inlarn. Sjfmp.. 1MB) (In Uw Siam). Trice, O.K.,Ptm,Kr 610(1070). I Wrlcbt, 8., Amer. Hat., H MO (IMS). Wrlfht. R., OtneHet, It. SM (IBM). ..' Wrifhl, 8 Ann. tnftniea, U, SM (1061). Wright, 8., Bug. A mar. Math. Boe.. 48. SM (1042). Ortano, 0. H.. and WUnoa, U. T., Heaton, U, 7M (10f4). . ' MnnhnS, A. J., BmmrtMi (Oxford UWt. Tnm, IBM). II Portat, r. 8., nod OriBUa; A., Pm. Keg. Jute nut. Bat.. A, W, 1M (IBM). " KMqpntrick, T. W,, tnaaat U)14a Me IVetn (Longmeae, Loadoa. lBfT). > Walter. W. O., Cmnad. J. Hm.,M, SM (7041). Source of Polychlorinated Biphenyl Contamination in tha Marina Environment Snrcx residues of polychlorinated biphenyls (PCBe) were identified in Swedish wildlife1, they have been reported tin many marine spooies*-'. Sample* of marine fish and molluscs from Scottish waters have been analysed far orgsnoohlorin* residues et this laboratory on several occasion* sines I960, and the concentrations of PCB reajftgM detected in these samples have been generally higheit from the Firth of Clyde. Therefore a wide variety of samples from this area was used in the autumn of IMl to try to establish tho route by which tho PCB residues rcacbod the fish. Samples of tho wator surface Aim and sub-surfooo wator were taken at various points in i| estuary, and also at S-mile intervals along the river to the oentre of Glasgow, to detect any local discharge* containing PCBe. No PCB residues oould bo found (limit of detection in water, 1 part in 10") and samples of effluents discharged from trunk sewers into the estuary and in the Glasgow area also showed no significant concentrations of PCBs. Concentrations in zooplankton by comparison were lens than 0-03 p.p.m. (3 parts in 1(H), and in clupeoid fish up to 2-0 p.p.m. (both oxpresnnd <m a wet weight basis). Polychlorinated biphenyls are produood by tho eon. trolled chlorination of biphenyl, and are made available for industrial use in various forma, mostly as liquids of different viscosities, aooording to the dogroe of chlorina tion. More than 200 compounds ore theoretically possible, and each commercial preparation oontains several indi vidual PCBs with different arrangements of the chlorine . atoms in the molecule. PCB compounds found in wildlife samples, using gas liquid chromatography at about 200 C, have been shown to contain mostly six to seven chlorine atoms', although compounds with more chlorine atoms may not be sufficiently volatile to be detectable at this temperature. For comparison with tho PCB residue# found in wildlife, a PCB mixture containing about 50 per cent by weight of chlorine is oommonly ueod os a reference (for example, 'Aroolor 1254', Mon santo Ltd). In Britain, effluents froth industry apart from thoM which are unacceptable are usually passed to sewage purification works for treatment with domestic aewogo. Samples of crude sewage sludge from such works in Glasgow and adjacent area* have been analysed for PCBs. The sludge from this area is transported by boots to the estuary and dumped in deep water 0 miles south of Garroch Head (Isle of Bute), at the rate of about a million wet tons per year. It oon therefore constitute a source of entry into the marine environment of some industrial waste products. Table l. BKATITX FX1K SBH1HTS IK SAS-UQCIB OSXOKATOSE4M8 Jt. SB 81 100* 121 145t 171 100 2*4 M MS 870 Sample Haw atorijn A M M tl 104 100 92 M It 11 10 1 Raw atodse B M 84 17 61 100 M 70 M 04 29 8ft 'Atoclor 1264' 80 78 M 110 100 Bt M 12 10 0 4 Arocks lMO' 8 14 4 to 100 SB 70 U 07 to ts * Tbta peak InrtadM pp'-DPB hi altirife. t Teak helfht -100 (or leferener. Although the extraction of orgonochlorine oompounds from sewage solids (using a mixture of n-hexane and isopropanol) is believed to be less efficient than extraction from water, it was nevertheless found that many of the sludge samples gave gas-liquid chromatograms similar to those of PCB mixtures. Table 1 allows tho proportions (in terms of relative peak heights) of the major peaks in typical chromatograms, os identified by their Rm values (retention time at 200 C relative to dieklrin 100). The column used was psekod with 10 per oent DC-200 tilioone on *Chromo#orb W'. PCB compounds were separated from all major orgonochlorine pesticide residues, except pp'-DDE, on silioa columns'. Thepeak pattern for sludge A is closely similar to that of a PCB formulation containing about 60 per oent by weight of chlorine (for example, Aroolor 1254'), but the pattern for sludge B suggests that it contains those PCBs of higher chlorine content in a greater proportion than A, and is saniku' to the pattern produced by 60 per oent chlorinated products (for example, 'Aroolor 1200*). On the basis of wet weight of crude sludge the estimated concentrations of PCBs, using `Aroolor 1204' as reference, in fifteen samples were in the range <0-1 to 14 p.pjn. (If 'Aroetor 1M0* is used os reference, the concentrations NATWP aro son ranged extract: somplw to give p.p.m. plants tions o origins oornod, the sow purpose uses an It th oooeysb sludge areas. 1 p.p.m aooordi to a dii of PCB Manchr were oi the Mir commit toehniq weight) at a rs 1 ton . Analyst sewage typical I arc dui to obou Whet introdu possible binod * without oould fc suspend as pract of PCB through have br labornb I the and the for new: Froshwt Pitlochi Beotian: Received . Jenven, Holden. RlMbrot M.H. Koemac Ml. 1 Hotten. meni ' JaaMn. (1BCB Hatm/, ' Holden. Reynold Relati Post-1 Horri Ih man three eg DSW 332454 STLCOPCB4079030 NATURE VOL. 2X8 DECEMBER 18 IB70 1221 am somewhat lower.) In term* of dry matter the value* ranged from 1 to 186 p.p.in. (value* uncnrrcctcd for sxtraetian sAoieoejr). Ths various plant* were each aapltd on throe occasions, and two plant* wore found to give tonaiatentljr high oonoentration* of PCB (60-100 P4jn. dry weight). The liquid effiuont* from theae plant* contained comparatively inaignifloant oonoontra* tiona of PCB. It hae proved impossible to looate the origin* of the PCB discharge* to the aewage plant* con cerned. beeauae eeveral hundred factoriea are linked to the sewers. The ohemioala can be uaed for many industrial purpoeo**, but it is not known how many of the possible use* are exploited in the Glasgow area. It thus seems possible that the PCBs in the Clyde ooosystem result from routine dumping of orude sewage sludge from treatment works in Glasgow and adjacent areas. An avsrage oonoentration of PCB of the onto of 1 p.p.m. (ee found in fifteen samples ofwot sludge weighted eeoording to the proportions dumped) would b* equivalent te a discharge in the Clyde estuary of the order of I ton of PCBs per year. Four sanmles of orude sludge from Manchester (dumped in the Northern Irish Sea), which were analysed at the Burnham-on-Crouch Laboratory of the Ministry of Agriculture, Fisheries and Food (personal communication uom J. E. Portmann) using similar techniques, contained between 0-1 and 6 p.p.m. (wet weight) of PCB*. If there is an average of 2 p.p.m. dumped at a rate of 0*8 million tons of sludge per year, about 1 ton of PCB isomers per year would be discharged. Analyses by the same laboratory of samples of London sewage sludge have shown that these contain lees PCB, typically of the order of 0-2 p.p.m. About 6 million tons are dumped off the Thame*' Estuary, again equivalent te about a ton of PCB isomer*. Where this form of sludge disposal is practised, the introduction of PCS# from industrial wastes is clearly possible. Some ooaatal towns, however, disoharge oom- bseed sewage and industrial waste* direct te the sea without treatment, and in auoh eaaee any PCBs present oould be expected to enter the ecosystem adsorbed to suspended solids. The disposal of sewage sludge on land, S* practised in inland areas, oould lead to the introduction of PCB residues into the terrestrial ecosystem by transfer through food chains. Bo far, however, no PCB residue* have been detected in freshwater fish in Sootland at this laboratory. I thank the City of Manchester Rivers Department and the Scientific Branch of the Greater London Council for sewage samples. Freshwater Fisheries Laboratory, A. V. Hoiomr FMoefarv, Sootland. Haertred Am* 10. l*Tt. . 1 Asses, S..M7j SttmVm, M. Oil (10*1). BoMsa. A. Y,, sat MinOi*. K,, Kmart, US, ltH (1007). B* Hermes, 8. 0., as* Kkiwt ' Zasiasa, 1. H. Tta Hesiw A Brasw. M. a, ui di Vos, B. It, Kmart, HoAhm, Imwnnwmt *>- It, sad OttariM, 0., Katart, M MT ' Bate* 1008 (1888). BolOoa. A, V., u4 MirnS--. X.. J. ' BsyaolW, L M., M Bus. DWas. 44, 4S1 (IMS). I 4. 1X8 (100*). VUfutkxuhip btwin Egg Siz and iWhiitchlM CMck Mortality In tha Hiring Cull (Una mygntnciig) br/maay gad species, the third laid egg of the typical ` : olutoh Is rtirttneOly smaller than the first two*'*. Kg rntame (cm*) Fla 1. The rehUomhlp betveaa so toIum sad poot-htehln* chirk mortaltjr/ninrfnU for each egg of the bjtas wqnesea. In the herring gull {Larva argantatua), the chick hatching from this third egg suffors a much higher mortalit y t han cither of its siblings', although the hatching aurorae in the same for all three eggs. In a aeries of egg transfer experiments carried out on the Isle of May, Scotland, it has been possible to demonstrate at least two factors contributing to this differential mortality, namely the sise disadvantage and the sequence of hatching, because third laid eggs normally hatch last. Although the survival of chicks from third eggs increased when they wore the first to hatch, it was etui lower than that of its siblings. To investigate this problem further, a detailed field study was made of the post-hatching survival of herring gull ohioks from more than 1,400 eggs of known volume''*. The survival of the chicks was followed by leg banding at hatching. Most of the mortality occurred in the first week after hatching4, and the mortality after that time wae independent of the sise of the egg from which the chick hatched. The fate of ohioks within the first seven days of life was therefore grouped according to egg volume and seqaenoe of laying (see Table 1 and Fig. I). Tmbta l. cdoi xosMUtr si rent a : or BAioenrs ooxtabsb wmt OUCniTB) mm Town la TofcnM so-so 80-88 88-70 70-76 "*5. Bo. dtod Par eeni morUStr `To. hstahod No. i Fori .., _ -- * 4 100 10 --0 -- so tt 7* M *4 4S 18 08 XT XX 10 58-4 46-8 SI-4 88-4 55 41 87 M 78 X6 80 XI 10 4 69 8 40-0 81-8 *4-4 10-0 18 . 00 86 M a ii - IT 48 ft IS xx i-- cent naorUltr NM'(4 81'7 88-8 605 418 81-8 -- For each egg of the laying sequence (referred to as the a, b and c eggs), there is a significant positive correlation between egg sise and chick survival (P<0'001), giving a range from approximately 80 per oent to 10 per cent survival. This relationship is similar for the first two eggs in a clutch, but although the slope is the same for the third egg, the survival is 10 per oent lower for eggs of the same sise. Thus the survival of the third hatched chick is lower than would be expected from its sise, but the most important factor m determining post hatching survival is the sise of the egg. Noarty all the ohioks from eggs smaller than 66 nm* (bed soon after hatching. Only 8 per oent of ell eggs laid were below tide sme, ana 88 per oent of these were e eggs. Egg sise ts positively correlated with eevertl factors including yolk weight and lipid (hexane soluble) content, as it is in otto speotes'. Furthermore, the weight of DSW 332455 STLCOPCB4079031