SPECIES SELECTION AND THE MACROEVOLUTION OF CORAL COLONIALITY AND PHOTOSYMBIOSIS

Differences in the relative diversification rates of species with variant traits are known as species selection. Species selection can produce a macroevolutionary change in the frequencies of traits by changing the relative number of species possessing each trait over time. But species selection is not the only process that can change the frequencies of traits, phyletic microevolution of traits within species and phylogenetic trait evolution among species, the tempo and mode of microevolution can also change trait frequencies. Species selection, phylogenetic, and phyletic processes can all contribute to large‐scale trends, reinforcing or canceling each other out. Even more complex interactions among macroevolutionary processes are possible when multiple covarying traits are involved. Here I present a multilevel macroevolutionary framework that is useful for understanding how macroevolutionary processes interact. It is useful for empirical studies using fossils, molecular phylogenies, or both. I illustrate the framework with the macroevolution of coloniality and photosymbiosis in scleractinian corals using a time‐calibrated molecular phylogeny. I find that standing phylogenetic variation in coloniality and photosymbiosis deflects the direction of macroevolution from the vector of species selection. Variation in these traits constrains species selection and results in a 200 million year macroevolutionary equilibrium.     

多元化互动优化医学免疫学课堂教学

根据医学免疫学的特点和我国教学现状,设计了多种互动式教学方式,通过创设问题情境,建立激励机制,创建团队,组织小组活动等,在课堂教学中创造愉快、和谐、平等、探究的气氛,最大限度的激发学生学习主动性、创造性,提高学生的综合素质,同时促进医学基础课的教学质量。为保证多元化互动式教学模式的顺利实施,尝试建立适合该教学模式的全新考核评价体系,在新的评价体系里,期末成绩（100％）=基础理论（50％）＋出勤及课堂表现（15％）＋实验操作与技能（20％）＋小组活动（15％）。在本项研究实施过程中设置了信息反馈环节,针对提高学习兴趣、强化基础知识、促进思考能力、创新能力、语言表达能力等方面设立问卷调查,及时获得信息反馈。多元化互动式教学模式还存在许多细节性的问题急待解决,还需要反复的推敲、探索与实践。     

亚洲高海拔锄足蟾的属间亲缘关系、分化及其与青藏高原形成的关系

本文在研究高海拔锄足蟾的属间分类及分布规律的基础上,对所属的齿蟾属Oreolalax、齿突蟾属Scutiger的齿突蟾亚属Scutiger,(Scutiger)和猫眼蟾亚属Scutiger(Aelurophryne)的成体外形和骨骼、蝌蚪的形态以及核型等24个性状进行综合分析,同时探讨了属间亲缘关系。结果表明:齿蟾属较原始,齿突蟾属较特化,它们可能起源于共同的祖先——原始齿蟾。在齿突蟾属中猫眼蟾亚属比齿突蟾亚属更为特化,后者与齿蟾属的亲缘关系相对较近。它们的分化与青藏高原的抬开有密切关系。     

Gill monogeneans of neotropical cichlid fish: diversity,phylogenetic relationships,and host-parasite cophylogenetic associations

Host-parasite coevolution is one of the main topics of the evolutionary biology of host-parasite associations. The majority of monogeneans parasitizing fish exhibit a high degree of host specificity. As a result, their evolutionary history might be intertwined with that of their fish hosts. The Cichlidae represent a diverse group of secondary freshwater fish with disjunctive distribution. Host-specific dactylogyrid monogeneans commonly parasitize cichlid fish. Their high diversity is associated with the main areas of cichlid distribution, i.e., Neotropical America and Africa. Nevertheless, the parasite fauna of cichlids from Neotropical America is still underexplored. A total of 31 cichlid species were examined for the presence of monogeneans, with 20 of them being parasitized. On these cichlids, 30 monogeneans belonging to the genera Gussevia, Trinidactylus, and Scadicleithrum were identified, 17 of them potentially representing new species for science. Phylogenetic analyses revealed three monophyletic groups of Neotropic cichlid monogeneans. Genus Gussevia was monophyletic, while Sciadicleithrum resulted polyphyletic. Sciedicleithrum from South America and Sciadicleithrum from Mexico represented two divergent lineages. The plesiomorphic Neotropical cichlid host group for dactylogyrid monogeneans was Cichlini, from which the representatives of other Neotropical cichlid tribes were colonised. Cophylogenetic analyses revealed a statistically significant cophylogenetic signal in the investigated host-parasite system, with host switch and duplication representing the main coevolutionary events for monogeneans parasitizing Neotropical cichlids. This scenario is in accordance with previous studies focussed on dactylogyridean monogeneans parasitizing freshwater fish in Europe and Africa.     

Phylogenetic evidence of a rapid radiation of pleurocarpous mosses (Bryophyta)

Abstract Pleurocarpous mosses, characterized by lateral female gametangia and highly branched, interwoven stems, comprise three orders and some 5000 species, or almost half of all moss diversity. Recent phylogenetic analyses resolve the Ptychomniales as sister to the Hypnales plus Hookeriales. Species richness is highly asymmetric with approximately 100 Ptychomniales, 750 Hookeriales, and 4400 Hypnales. Chloroplast DNA (cpDNA) sequences were obtained to compare partitioning of molecular diversity among the orders with estimates of species richness, and to test the hypothesis that either the Hookeriales or Hypnales underwent a period (or periods) of exceptionally rapid diversification. Levels of biodiversity were quantified using explicitly historical "phylogenetic diversity" and non-historical estimates of standing sequence diversity. Diversification rates were visualized using lineage-through-time (LTT) plots, and statistical tests of alternative diversification models were performed using the methods of Paradis (1997). The effects of incomplete sampling on the shape of LTT plots and performance of statistical tests were investigated using simulated phylogenies with incomplete sampling. Despite a much larger number of accepted species, the Hypnales contain lower levels of (cpDNA) biodiversity than their sister group, the Hookeriales, based on all molecular measures. Simulations confirm previous results that incomplete sampling yields diversification patterns that appear to reflect a decreasing rate through time, even when the true phylogenies were simulated with constant rates. Comparisons between simulated results and empirical data indicate that a constant rate of diversification cannot be rejected for the Hookeriales. The Hypnales, however, appear to have undergone a period of exceptionally rapid diversification for the earliest 20% of their history.     

Phylogenetic analysis of the latitude‐niche breadth hypothesis in the butterfly subfamily Nymphalinae

1. One possible explanation for the latitudinal gradient in species richness often demonstrated is a related gradient in niche breadth, which may allow for denser species packing in the more stable environments at low latitudes. 2. The evidence for such a gradient is, however, ambiguous, and the results have varied as much as the methods. Several studies have considered the non‐independence of species, but few have performed explicit phylogenetic analyses. 3. In the present study, we tested for a correlation between diet breadth and latitude of distribution in Nymphalinae butterflies using generalised estimating equations (GEE) and accounting for phylogenetic independence. 4. Using a simple model with only latitude of distribution as a predictor variable revealed a significant positive relationship with diet breadth. Previous studies, however, have shown that diet breadth is also correlated with butterfly range size, and in turn, that range size may be correlated with latitude of distribution. Including geographical range size in the model also turned out to have a profound effect on the results – to the extent that the relationship between latitude of distribution and diet breadth was effectively reversed. 5. We conclude that, at least for this group of butterflies, there is no evidence for a positive correlation between latitude of species distribution and diet breadth when controlling for range size, and that the effect may actually even be reversed.     

Asymmetries in phylogenetic diversification and character change can be untangled

The analysis of diversification and character evolution using phylogenetic data attracts increasing interest from biologists. Recent statistical developments have resulted in a variety of tools for the inference of macroevolutionary processes in a phylogenetic context. In a recent paper Maddison (2006 Evolution, 60: 1743-1746) pointed out that uncareful use of some of these tools could lead to misleading conclusions on diversification or character evolution, and thus to difficulties in distinguishing both phenomena. I here present guidelines for the analyses of macroevolutionary data that may help to avoid these problems. The proper use of recently developed statistical methods may help to untangle diversification and character change, and so will allow us to address important evolutionary questions.     

The impact of Rhinanthus minor in newly established meadows on a productive site

Question: What is the impact of the presence of Rhinanthus minor on forb abundance in newly established swards? Location: Wetherby, West Yorkshire, UK (53°55’N, 1°22’W). Method: A standard meadow mix containing six forbs and six grasses was sown on an ex‐arable field and immediately over‐sown using a randomised plot design with three densities of Rhinanthus minor (0, 600, and 1000 seeds per m²). Above‐ground biomass was analysed over a period of three years, while detailed assessments of sward composition were performed during the first two years. Results: Values of grass biomass were reduced in the presence of Rhinanthus, especially at the higher sowing density. The ratio of grass: forb biomass was also lower in association with Rhinanthus, but only at the higher sowing density. The presence of Rhinanthus had no effect on species number or diversity, which decreased between years regardless of treatment. Conclusions: Although not tested in a multi‐site experiment, the benefit of introducing Rhinanthus into newly established swards to promote forb abundance was determined. The efficacy of Rhinanthus presence is likely to depend on whether species not susceptible to the effects of parasitism are present.     

The early evolution of ray‐finned fishes

Ray‐finned fishes (Actinopterygii) constitute approximately half of all living vertebrate species. A stable hypothesis of relationships among major modern lineages has emerged over the past decade, supported by both anatomy and molecules. Diversity is unevenly partitioned across the actinopterygian tree, with most species concentrated within a handful of geologically young (i.e. Cretaceous) teleost clades. Extant non‐teleost groups are portrayed as ‘living fossils’, but this moniker should not be taken as evidence of especially primitive structure: each of these lineages is characterized by profound specializations. Attribution of fossils to the crowns and apical stems of Cladistia, Chondrostei and Neopterygii is uncontroversial, but placements of Palaeozoic taxa along deeper branches of actinopterygian phylogeny are less secure. Despite these limitations, some major outlines of actinopterygian diversification seem reasonably clear from the fossil record: low richness and disparity in the Devonian; elevated morphological variety, linked to increases in taxonomic dominance, in the early Carboniferous; and further gains in taxonomic dominance in the Early Triassic associated with earliest appearance of trophically diverse crown neopterygians.