中国麻黄属植物的分类——兼论麻黄属的演化

根据中国麻黄属植物分类及麻黄属起源和演化研究中存在的争论，本论文主要进行了分类学、形态学、微形态学、解剖学、形态发生学、孢粉学、古植物学、植物生态学和植物地理学等方面的研究。 1、分类学 从性状变异式样的分析入手，结合标本馆工作和野外调查，确认了中国麻黄属植物共有13个种;合并了丽江麻黄(Ephedra likiangensis)、雌雄麻黄(E. fedtschenkoae);澄清了前人在细子麻黄(E. regeliana)、灰麻黄(E. glauca)、草麻黄(E. sinica)和双穗麻黄(E. distachya)等种类鉴定中混乱的问题，并描述了一个新种——日土麻黄（Ephedra rituensis Y. Yang, D. Z. Fu et G. Zhu）。 2、形态学 提供了中国麻黄属种类的标本（包括模式标本）照片资料及中国麻黄属植物的雌球花和雄球花的照片资料，为麻黄属分类和系统学研究提供了证据。 3、微形态学 首次报道了中国麻黄属植物的种子表面微形态特征，聚合囊表面纹饰、小枝表面特征。 种子表面特征可分为4种类型。类型I：种子表面平滑，包括：中麻黄(Ephedra intermedia)、双穗麻黄、细子麻黄等;类型II：种子表面具疣状突起，仅发现木贼麻黄(E. equisetina)一种;类型III：种子表面具横向片层状突起，仅有斑子麻黄(E. rhytidosperma)一种;类型IV：种子表面具纵条纹，包括喜马拉雅特有的3个大种子的种类，即矮麻黄(E. minuta)、山岭麻黄(E. gerardiana)和藏麻黄(E. saxatilis)。 对小枝表面扫描电镜下的微形态构造的研究并没有发现前人报道的毛状体特征，而只有一些疣状角质突起和有变异的气孔，同时注意到，麻黄属植物的小枝表面特征受到生境、发育阶段的影响。 麻黄属聚合囊顶孔开口处具脑波状纹饰，而聚合囊表面纹饰具二级纹饰。麻黄属聚合囊表面纹饰非常独特，为该属在地层中雄性生殖构造的发现提供了可参考的性状。 4、孢粉学 补充了麻黄属中非常特化的种——斑子麻黄的孢粉资料，同时也对膜果麻黄(Ephedra przewalskii)、中麻黄、细子麻黄和木贼麻黄的孢粉重新进行了研究。结果表明斑子麻黄的花粉形态也非常特殊，其纵肋数目5条左右，纵肋波状扭曲，肋间沟槽内透明线发达且分枝。膜果麻黄的花粉与前人描述的一致，但是，中麻黄、细子麻黄和木贼麻黄的花粉形态可能受到发育的影响而与前人报道中描述的有些差异。讨论了麻黄属4种花粉类型的演化趋势。 5、形态发生学 对麻黄属雌球花三种代表类型的个体发育研究表明，三胚珠球花发育早期球花主轴的顶芽发育，双胚珠球花的顶芽没有发育，而在单胚珠球花中，雌性生殖单位直接占据顶芽的位置发育。这三种类型也代表了麻黄属球花演化的三个阶段，三胚珠球花代表麻黄属雌球花的原始式样，而单胚珠雌球花则为麻黄属雌球花最为特化的式样。总之，麻黄属雌球花有简化的趋势，伴随着这种趋势，雌球花苞片数目减少、种子数目减少、种子体积增大、表面复杂度增加。 6、解剖学 对斑子麻黄种子表面微构造的形态发生及解剖研究表明，斑子麻黄雌性生殖单位发育早期，其表面为平滑型，因此，突起为次生的。这些突起是由雌性生殖单位外盖被表皮细胞的外壁向外突出形成，这种突出生长常常在相邻细胞之间同时发生，因此，出现片层状构造。石蜡切片显示，这些突起在发育早期有完整的细胞核、细胞质等结构，但在种子发育晚期和成熟后，这些外壁突起的细胞成为空腔隙，本文对这种构造的生态学意义进行了分析。 7、古植物学 本文描述了早白垩麻黄科的2个大化石种。 古斑子麻黄（Ephedra archaeorhytidosperma Y. Yang, B. Y. Geng et D. L. Dilcher et Z. D. Chen）发现于辽西义县组尖山沟层，时代为早白垩的芭雷姆期。该种的雌球花具2对苞片、1或2枚种子、珠孔管短直或顶部稍弯、种子表面具横列片层状纹饰等特征而与现存的斑子麻黄特征最为相近。二者之间如此多的相似之处只有一种解释，那就是它们曾经有过共同祖先。因此，该种应归属于麻黄属的肉苞组。古斑子麻黄雌球花特征的稳定性同时也表明，在麻黄属中也存在所谓的“形态演化停滞现象（morphological stasis）”，而这种现象也是首次在买麻藤类植物中报道。 星学异麻黄（Alloephedra xingxueii J. R. Tao et Y. Yang）产于吉林大拉子组，时代属早白垩的阿普特期——阿尔布期。该种雌球花具2对苞片、2枚种子，种子长椭圆形且具短的珠孔管与现存麻黄科植物最为相近，但是，其分枝式样与麻黄属不同，因此，本文在麻黄科中建立了一新属新种。此外，麻黄科植物常被看作是干旱区植被的代表，但是，对星学异麻黄当时所处的环境研究发现，大拉子组当时具有较明显的亚热带气候条件下的植被性质，因此，星学异麻黄即使需要干旱的条件，可能也只是局部小生境的条件。 8、生态学和植物地理学 本文首次对麻黄属植物生存环境中的水热条件进行了调查。从所选择的8个分布点来看，除了拉萨外，在麻黄属生殖生长期，其余7个分布点的湿度均是一年中最底的时期，而温度在这个时期逐渐升高。 对各地区内麻黄属种类的分布情况的分析发现，麻黄属的种类主要集中在三个地区，一是我国西北、前苏联的中亚地区及邻近地区，二是美国西南部、墨西哥西北部的地区，三是南美的智利、阿根廷等地。

中麻黄(Ephedra intermedia)胚胎发育及双受精作用在进化上的意义

本文对中麻黄(Ephedra intermedia)的双受精作用进行了较为详细的研究。其主要结果如下： 1．中麻黄约5月中旬传粉，5月下旬受精。中央细胞分裂形成卵核及腹沟核。卵核沿合点端方向移至卵细胞质富含细胞器区，被富含细胞器的细胞质所包围。卵核的受精发生在浓厚卵细胞质区内。精子向卵核靠近，穿过浓厚细胞质区，与卵核建立联系，二核逐渐靠拢。卵核核膜出现凹陷，并逐渐包围精子，最后完成受精。刚受精后的精核卵核的核质并不立即融合，各自保持独立。之后不久，二核完成融合，形成合子。 2．腹沟核刚形成后， 并不退化而是继续发育，并象卵核一样沿合点端方向从其顶端位置向卵细胞基部移动至卵细胞质富含细胞器区。第二个精子向腹沟核移动，靠近，并建立联系，最后完成融合，形成第二个合子。 3．双受精是中麻黄的正常生殖特征。中麻黄的双受精及第二次受精产物的命运具有重要的进化上的意义。 4．两个合子连续二次分裂形成八个游离核，或者叫次生合子。八个游离核进一步发育并细胞化形成具胚性功能的单细胞原胚．或者次生合子进一步分裂增殖形成多余游离核后再进一步发育并细胞化形成具胚性功能的单细原胚或在胚的发育中解体退化，以提供营养．一个胚珠可观察到一至七个发育时期不同的胚成熟胚珠中只有一个成熟胚，双子叶。 5．由游离核发育而来的单细胞原胚在进一步的发育中沿合点端方向向配子体内上移并形成单细胞球形胚。单细胞球形胚分裂形成二细胞胚，即胚原始细胞及胚柄细胞。胚原始细胞先进行一次平周分裂而后进行一次垂周分裂形成四细胞胚。之后胚体进一步分裂发育形成多细胞球形胚。发育至一定时期后，胚柄细胞及次生胚柄分裂、膨大、伸长形成胚柄，胚柄细胞逐渐增多、增长、弯曲疏松，成熟的胚中胚柄系统消失。胚体发育至圆柱状后，中央一层弧行排列的细胞形成根冠原始细胞，之后这些根冠原始细胞不断分裂、发育分化形成成熟胚的各种组织包括胚皮层、髓、原形成层及根冠等等。

Modeling the effect of striped bass (Morone saxatilis) on the population viability of Sacramento River winter-run chinook salmon (Onchorhynchus tshawytscha)

We estimated the impact of striped bass (Morone saxatilis) predation on winter-run chinook salmon (Oncorhynchus tshawytscha) with a Bayesian population dynamics model using striped bass and winter-run chinook salmon population abundance data. Winter-run chinook salmon extinction and recovery probabilities under different future striped bass abundance levels were estimated by simulating from the posterior distribution of model parameters. The model predicts that if the striped bass population declines to 512,000 adults as expected in the absence of stocking, winter-run chinook salmon will have about a 28% chance of quasi-extinction (defined as three consecutive spawning runs of fewer than 200 adults) within 50 years. If stocking stabilizes the striped bass population at 700,000 adults, the predicted quasi-extinction probability is 30%. A more ambitious stocking program that maintains a population of 3 million adult striped bass would increase the predicted quasi-extinction probability to 55%. Extinction probability, but not recovery probability, was fairly insensitive to assumptions about density dependence. We conclude that winter-run chinook salmon face a serious extinction risk without augmentation of the striped bass population and that substantial increases in striped bass abundance could significantly increase the threat to winter-run chi-nook salmon if not mitigated by increasing winter chinook salmon survival in some other way.

Diet composition of large striped bass (Morone saxatilis) in Chesapeake Bay

Large (>458 mm) striped bass (Morone saxatilis) are dominant predators in Chesapeake Bay. In recent years, the Chesapeake Bay stock of striped bass has increased dramatically, raising concerns about their predatory impact and their forage requirements. In response to these concerns and the need for more recent ecological studies, this investigation was conducted to characterize feeding habits of large striped bass in Chesapeake Bay. Stomach contents from 1225 striped bass from 458 to 1151 mm TL were examined in the spring and fall of 1997 and 1998. Striped bass consumed 52 different species of vertebrates and invertebrates; however, only a few species of clupeoid and sciaenid fishes dominated diets across both the seasons and size ranges of striped bass examined. Of finfish species, menhaden (Brevoortia tyrannus) was the dominant prey in most areas and gizzard shad (Dorosoma cepedianum) replaced menhaden in importance in lower salinity waters. Spot (Leiostomus xanthurus) and other sciaenid fishes and anadromous herrings (Alosa spp.) also contibuted large percentages of striped bass diet. Although pelagic schooling fishes formed the majority of the diet, benthic fishes contributed a higher percentage to the diet than in previous studies of striped bass diet composition.

Mycobacteriosis in Chesapeake Bay Striped Bass (Morone saxatilis): The Interaction of Nutrition and Disease

Field and laboratory studies were conducted from 1998 - 2005 to examine the relationship between nutritional status and mycobacteriosis in Chesapeake Bay striped bass (Morone saxatilis). A review of DNA from archived tissue blocks indicated that the disease has been present since at least 1984. Field surveys and feeding trials were conducted from 1998-1999 to determine the nutritional condition of striped bass and the association with disease state. Proximate composition revealed elevated moisture (~ 80%) and low storage lipids (< 0.5% ww), characteristic of a poorly nourished population. These findings were not consistent with data collected in 1990-1991, or with experimentally fed fish. Mycobacteriosis explained little of the variance in chemical composition (p > 0.2); however elevated moisture and low lipid concentration were associated with fish with ulcerative lesions (p < 0.05). This suggests that age 3 and 4 striped bass were in poor nutritional health in 1998-1999, which may be independent from the disease process. Challenge studies were performed to address the hypothesis that disease progression and severity may be altered by nutritional status of the host. Intraperitoneal inoculation of 104 CFU M. marinum resulted in high mortality, elevated bacterial density, and poor granuloma formation in low ration (0.15% bw/d) groups while adequately fed fish (1% bw/d) followed a normal course of granulomatous inflammation with low mortality to a steady, equilibrium state. Further, we demonstrated that an active inflammatory state could be reactivated in fish through reductions in total diet. The energetic demand of mycobacteriosis, was insignificant in comparison to sham inoculated controls in adequately fed fish (p > 0.05). Declines in total body energy were only apparent during active, inflammatory stages of disease. Overall, these findings suggest that: 1) mycobacteriosis is not a new disease of Chesapeake Bay striped bass, 2) the disease has little energetic demand in the normal, chronic progression, and 3) poor nutritional health can greatly enhance the progression and severity, and reactivation of disease. The implications of this research are that management strategies focused on enhancing the nutritional state of striped bass could potentially alter the disease dynamics in Chesapeake Bay.

Characterization of polymorphic microsatellites for the rough periwinkle gastropod, Littorina saxatilis (Olivi, 1792) and their cross-amplification in four congeners.

Eight new microsatellite loci were characterized for Littorina saxatilis (Olivi, 1792) and tested for their cross-hybridization in congeners. All loci were polymorphic in Irish and Celtic Sea samples, with an average number of alleles per locus of 15 (range, 6–31). Observed and expected locus heterozygosities ranged from 26 to 85% and from 53 to 92%, respectively. Three loci showed excess homozygosity and significant departures from Hardy–Weinberg expectations in one sample, possibly due to null alleles, population structuring or inbreeding. No linkage disequilibrium was detected among loci within samples. A high degree of cross-hybridization was observed in closely related congeners and most loci were polymorphic. These markers will be useful for investigating population genetic diversity and connectivity in coastal populations, especially for marine reserve design.

Evaluación hematológica de tres especies de peces Ictalurus punctatus, Morone saxatilis y Micropterus salmoides, en condiciones de desnutrición [por] Francisco Javier Alvarez Mendoza

Tesis (Maestría en Ciencias con Especialidad en Ecología Acuática y Pesca) U.A.N.L.

Chauliocheilos saxatilis, a new genus and species of Hypoptopomatinae from rio Jequitinhonha basin, with a unique labial appendix (Teleostei: Loricariidae)

Chauliocheilos saxatilis, new genus and species, is described from headwater streams of the rio Itamarandiba, upper rio Jequitinhonha basin, southeastern Brazil. The new genus is diagnosed from all other Loricariidae members by having a unique labial appendix at laterodorsal portion of lower lip, associated to the proximal region of insertion of the maxillary barbel. From all Hypoptopomatinae genera, Chauliocheilos can be distinguished by having two additional series of lateral plates, one between the dorsal and mid-dorsal series, and the other between the mid-ventral and ventral series. In addition, the great number of lateral plates, the absence of the iris operculum, and the posterior dorsal-fin insertion contacting the neural spine of eighth vertebra, are other useful features to recognize the genus. The phylogenetic position of Chauliocheilos among the Hypoptopomatinae, as well as the morphology and possible functions of the labial appendix, are discussed.