加州Santa Monica海湾鳍足类的生态学

研究了加州Santa Monica海湾鳍足类的生态学.从1997-2007年乘船调查了277次,发现海狮(Zalophus californianus)是最常见的动物(89%,见到的次数为1393次),其次是港海豹(Phoca vitulina richardsi,8%,n=131)和北象海豹(Mirounga angustirostris,1%,n=15).在29%的遇见次数(观察到瓶海豚205次)中,发现海狮(偶尔也发现港海豹)与瓶鼻海豚集群(Tursiops truncatus);短喙真海豚(Delphinus delphis)与长喙真海豚(D.capensis)在53% 的遇见次数(遇见真海豚次数n=155)中,发现短喙真海豚(Delphinus delphis)与长喙真海豚(D.capensis)集群;一般在沿岸水域(离岸边距离<500 m)见到海狮和港海豹,但在整个海湾也能见到,表现出这两个物种对海底峡谷的偏爱.北象海豹仅见于近海,主要在海底峡谷附近. 经常看到海狮、港海豹和北象海豹游动(50%,n=728)、进行热调节(14%,n=205)、以及取食(3.2%,n=47),但几乎见不到有社会性活动(0.21%,n=3).     

蝗虫复眼光谱敏感性的比较研究——Ⅱ.视网膜电图的光谱敏感曲线

(1)用视网膜电图(ERG)方法测定了9种蝗虫在黑暗、蓝光和橙光适应下的光谱敏感性。(2)9种蝗虫的碚适应光谱敏感曲线峰值均在520—546nm 之间。(3)橙光或蓝光明适应导致不同程度的峰值位移,蓝区的相对敏感性提高,这与光引起屏蔽色素移动效应有关。(4)黑背蝗和稻蝗复眼表面均没有黑白间,橙光适应时出现第二个峰值在蓝区,而蓝光适应则压抑蓝区的敏感性。可能这两种蝗虫还具有蓝敏视色素。(5)佛蝗和黄脊蝗复眼表面均有明显的黑白相间的区域,在有色光适应下这两种蝗虫的光谱敏感性变化最小,没有证据说明多于一种光敏色素。     

An immunogenetic basis for the high prevalence of urogenital cancer in a free-ranging population of California sea lions (Zalophus californianus)

In response to an unprecedented prevalence of cancer recently identified in free-ranging populations of California sea lions [(CSL) (Zalophus californianus], we examined the role of the immunologically important major histocompatibility (MHC) genes in this disease epidemic. Associations between MHC genes and cancer have been well established in humans, but have never before been investigated in wildlife. Using a previously developed technique employing sequence-specific primer-based PCR with intercalating dye technology, MHC genotypes were examined from 27 cancer-positive and 22 cancer-negative CSL stranded along the California coastline. Analyses elucidated an underlying immunogenetic component to the high prevalence of urogenital cancer in sea lions. Furthermore, these results demonstrate the functional relevance of CSL class II MHC by revealing a non-random nature of cancer susceptibility associated with the presence of specific genes.     

CAN NEAR INFRARED SPECTROSCOPY BE USED TO IMPROVE ASSESSMENT OF MARINE MAMMAL DIETS VIA FECAL ANALYSIS?

We investigated the utility of Near Infrared Spectroscopy as a means to quantify the diet of seals via analysis of feces. A pilot study showed that we could accurately determine the proportion of each species in a mixture of flesh of two species of fish and one squid. Having done so, we then assessed whether the same capacity existed for fecal material. Again we used two species of fish and one squid as the diet components offered to two captive seals (a California sea lion and an Australian fur seal). Five of the six calibrations could accurately and precisely quantify how much of a given diet component the seal had eaten the previous day from an NIR scan of the feces. NIR spectroscopy is theoretically a viable way to quantify seal diets. We discuss the logistical requirements for development of calibration equations for application to a field study. These may be prohibitive in many cases, but in others may be offset by the particular circumstances or objectives of the study. Adoption of NIRS may confer significant benefits in these circumstances.     

INVESTIGATING TROPHIC RELATIONSHIPS OF PINNIPEDS IN ALASKA AND WASHINGTON USING STABLE ISOTOPE RATIOS OF NITROGEN AND CARBON

We measured stable-nitrogen (δ¹⁵N) and stable-carbon (δ¹³C) isotope ratios in muscle and hair from 7 northern fur seals (Callorhinus ursinus) from the Pribilof Islands, Alaska, and 27 Steller sea lions (Eumetopias jubatus), and 14 harbor seals (Phoca vitulina) from the Gulf of Alaska and coast of Washington State, in order to contrast dietary information derived from isotopic vs. available conventional dietary studies. Stable-nitrogen-isotope analysis of muscle revealed that harbor seals were enriched over sea lions (mean δ¹⁵N = 18.6‰vs. 17.5‰) which were in turn enriched over northern fur seals (mean δ¹⁵N = 16.6‰). Trophic segregation among these species likely results primarily from differential reliance on herring (Clupea harengus), Atka mackerel (Pleurogrammus monopterygius), and large vs. small walleye pollock (Theregra chalcogramma). According to their δ¹⁵N values, adult male Steller sea lions showed a higher trophic position than adult females (mean δ¹⁵N: 18.0‰vs. 17.2‰), whereas adult female northern fur seals were trophically higher than juvenile male fur seals (mean δ¹⁵N: 16.5‰vs. 15.0‰). Each of these observed differences likely resulted from differential reliance on squid or differences in the size range of pollock consumed. Three northern fur seal pups showed higher δ¹⁵N enrichment over adults (mean 17.7‰vs. 15.8‰) due to their reliance on their mother's milk. Stable-carbon isotope measurements of hair revealed a cline toward more negative values with latitude. Segregation in hair δ¹³C between Steller sea lions and harbor seals off the coast of Washington (mean δ¹³C: ?13.6‰vs.?15.0‰) reflected the greater association of harbor seals with freshwater input from the Columbia River. Our study demonstrates the utility of the stable isotope approach to augment conventional dietary analyses of pinnipeds and other marine mammals.     

Common cancer in a wild animal: the California sea lion (Zalophus californianus) as an emerging model for carcinogenesis

Naturally occurring cancers in non-laboratory species have great potential in helping to decipher the often complex causes of neoplasia. Wild animal models could add substantially to our understanding of carcinogenesis, particularly of genetic and environmental interactions, but they are currently underutilized. Studying neoplasia in wild animals is difficult and especially challenging in marine mammals owing to their inaccessibility, lack of exposure history, and ethical, logistical and legal limits on experimentation. Despite this, California sea lions (Zalophus californianus) offer an opportunity to investigate risk factors for neoplasia development that have implications for terrestrial mammals and humans who share much of their environment and diet. A relatively accessible California sea lion population on the west coast of the USA has a high prevalence of urogenital carcinoma and is regularly sampled during veterinary care in wildlife rehabilitation centres. Collaborative studies have revealed that genotype, persistent organic pollutants and a herpesvirus are all associated with this cancer. This paper reviews research to date on the epidemiology and pathogenesis of urogenital carcinoma in this species, and presents the California sea lion as an important and currently underexploited wild animal model of carcinogenesis.     

SEX DETERMINATION OF THE CALIFORNIA SEA LION (ZALOPHUS CALIFORNIANUS CALIFORNIANUS) FROM CANINE TEETH

Size of canine teeth from California sea lion ( Zalophus californianus californianus ) carcasses is shown to be useful in determining the sex of animals which have missing genitalia or which are otherwise of unknown sex. A total of 267 canine teeth from carcasses of 68 males and 43 females were measured along five axes. Of root and crown measurements of upper and lower canines, males and females overlapped only in root thickness of upper canines. A multivariate ANOVA showed a significant difference in the size of canines between upper and lower canines, and between males and females. Stepwise discriminant analysis produced discriminant functions for upper and lower canines for determining sex of unknown-sexed California sea lions. A separate set of canine teeth from 39 male and 49 female California sea lions was correctly classified without prior knowledge of sex by visual inspection and by the two discriminant functions.     

Differentiating between Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) scats through analysis of faecal DNA

We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.     

MHC gene configuration variation in geographically disparate populations of California sea lions (Zalophus californianus)

Major histocompatibility complex (MHC) class II DRB genotypes were examined in two geographically isolated populations of California sea lions (Zalophus californianus) (Gulf of California and California coastal Pacific Ocean). Genomic DNA from 227 California sea lions was examined using eight sequence-specific primer (SSP) pairs flanking the putative peptide-binding site. A total of 40 different Zaca-DRB genotype configurations were identified among the 227 individuals. Using SSP-PCR, significant differences were found between coastal California and Gulf of California Zalophus populations in numbers of DRB sequences per individual and configuration of sequences within individuals. Additionally, unique local patterns of MHC diversity were identified among the Midriff Island animals. These population differences are consistent with either ecologically distinct patterns of selection pressures and/or geographical isolation. The consequences of these partitioned MHC configurations at the population level are as yet unknown; however, the worldwide increase in emerging marine diseases lends urgency to their examination.