Phylogeography of the parasitic fly Batrachomyia in the Wet Tropics of north-east Australia, and susceptibility of host frog lineages in a mosaic contact zone

Parasites could differentially impact intraspecific host lineages due to genetic, phenotypic, ecological, or behavioural differences between the lineages, or the development of reproductive isolation between them. Batrachomyia (Diptera: Chloropidae) are flies that exclusively parasitize Australian frogs, and in the Wet Tropics rainforest of north‐east Australia larvae are largely restricted to the green‐eyed tree frog Litoria genimaculata (Anura: Hylidae). This frog species consists of two highly divergent genetic lineages that overlap in two nearby, but independent, contact zones. At one contact zone there has been extensive phenotypic divergence and speciation between the lineages whereas, at the other contact relatively lower levels of phenotypic divergence and reproductive isolation suggest that speciation has not occurred. In the present study we tested: (1) whether the deep phylogeographic divergence between northern and southern host populations is mirrored by congruent genetic structuring in the parasite populations and (2) whether the host lineages are differentially impacted by parasitism. We found that the two divergent frog lineages are parasitized by a single lineage of Batrachomyia, which exhibits strikingly little phylogeographic structuring. We found a significant difference in Batrachomyia prevalence between the host lineages at mixed lineage sites in both contact zones, with the magnitude and direction of this effect being consistent in both. The pattern did not differ between the two contacts even though recent phenotypic divergence and speciation has occurred between the lineages at one contact but not the other. Taken together, this suggests a fundamental difference in susceptibility between the genetically divergent host lineages. Using weight relative to body length as a measure of body condition, we found no differential impact of parasitism on the body condition of each host lineage, and no evidence that parasitism impacts the body condition of the host in general. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92 , 593–603.     

Dispersal,fragmentation, and isolation shape the phylogeography of the European lineages of Polyommatus (Agrodiaetus) ripartii (Lepidoptera: Lycaenidae)

Polyommatus ripartii is a biogeographically and taxonomically poorly understood species of butterfly with a scattered distribution in Europe. Recently, it has been shown that this species includes several European endemic and localized taxa (galloi, exuberans, agenjoi) that were previously considered species and even protected, a result that poses further questions about the processes that led to its current distribution. We analysed mitochondrial DNA and the morphology of P. ripartii specimens to study the phylogeography of European populations. Three genetically differentiated but apparently synmorphic lineages occur in Europe that could be considered evolutionarily significant units for conservation. Their strongly fragmented and counterintuitive distribution seems to be the result of multiple range expansions and contractions along Pleistocene climatic oscillations. Remarkably, based on the 79 specimens studied, these genetic lineages do not seem to extensively coexist in the distributional mosaic, a phenomenon most evident in the Iberian Peninsula. One of the important gaps in the European distribution of P. ripartii is reduced by the discovery of new Croatian populations, which also facilitate a better understanding of the biogeography of the species. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 817‐829.     

There's no place like home: seedling mortality contributes to the habitat specialisation of tree species across Amazonia

Understanding the mechanisms generating species distributions remains a challenge, especially in hyperdiverse tropical forests. We evaluated the role of rainfall variation, soil gradients and herbivory on seedling mortality, and how variation in seedling performance along these gradients contributes to habitat specialisation. In a 4‐year experiment, replicated at the two extremes of the Amazon basin, we reciprocally transplanted 4638 tree seedlings of 41 habitat‐specialist species from seven phylogenetic lineages among the three most important forest habitats of lowland Amazonia. Rainfall variation, flooding and soil gradients strongly influenced seedling mortality, whereas herbivory had negligible impact. Seedling mortality varied strongly among habitats, consistent with predictions for habitat specialists in most lineages. This suggests that seedling performance is a primary determinant of the habitat associations of adult trees across Amazonia. It further suggests that tree diversity, currently mostly harboured in terra firme forests, may be strongly impacted by the predicted climate changes in Amazonia.     

‘Fish’ (Actinopterygii and Elasmobranchii) diversification patterns through deep time

Actinopterygii (ray‐finned fishes) and Elasmobranchii (sharks, skates and rays) represent more than half of today's vertebrate taxic diversity (approximately 33000 species) and form the largest component of vertebrate diversity in extant aquatic ecosystems. Yet, patterns of ‘fish’ evolutionary history remain insufficiently understood and previous studies generally treated each group independently mainly because of their contrasting fossil record composition and corresponding sampling strategies. Because direct reading of palaeodiversity curves is affected by several biases affecting the fossil record, analytical approaches are needed to correct for these biases. In this review, we propose a comprehensive analysis based on comparison of large data sets related to competing phylogenies (including all Recent and fossil taxa) and the fossil record for both groups during the Mesozoic–Cainozoic interval. This approach provides information on the ‘fish’ fossil record quality and on the corrected ‘fish’ deep‐time phylogenetic palaeodiversity signals, with special emphasis on diversification events. Because taxonomic information is preserved after analytical treatment, identified palaeodiversity events are considered both quantitatively and qualitatively and put within corresponding palaeoenvironmental and biological settings. Results indicate a better fossil record quality for elasmobranchs due to their microfossil‐like fossil distribution and their very low diversity in freshwater systems, whereas freshwater actinopterygians are diverse in this realm with lower preservation potential. Several important diversification events are identified at familial and generic levels for elasmobranchs, and marine and freshwater actinopterygians, namely in the Early–Middle Jurassic (elasmobranchs), Late Jurassic (actinopterygians), Early Cretaceous (elasmobranchs, freshwater actinopterygians), Cenomanian (all groups) and the Paleocene–Eocene interval (all groups), the latter two representing the two most exceptional radiations among vertebrates. For each of these events along with the Cretaceous‐Paleogene extinction, we provide an in‐depth review of the taxa involved and factors that may have influenced the diversity patterns observed. Among these, palaeotemperatures, sea‐levels, ocean circulation and productivity as well as continent fragmentation and environment heterogeneity (reef environments) are parameters that largely impacted on ‘fish’ evolutionary history, along with other biotic constraints.     

Ancient Mitogenomes Reveal the Evolutionary History and Biogeography of Sloths

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关于物种濒危等级标准之探讨--对IUCN物种濒危等级的思考

为了保存地球上的生物多样性,我们需要根据物种的种群数量与分布、种群数量波动与分布区下降速率来评定濒危物种的濒危等级,并针对物种的濒危等级提出具体的保护措施。1994年11月,IUCN第40次理事会会议正式通过了经过修订的Mace-Lande物种濒危等级标准作为IUCN物种濒危等级标准。IUCN濒危物种红色名录虽然不是国际法和国家法律,但是对于政府间组织、非政府组织的保护决策以及各国的自然法律法规的制定有着深远的影响,在保护生物学理论研究中也发挥了一定作用。我们在研究制定中国水生野生生物濒危等级标准时发现,如果直接应用IUCN物种濒危等级标准评定水生野生生物濒危等级将存在一些问题。如：(1)如何区别对待那些本来就数量稀少、分布区狭窄的物种和那些由于人类活动而导致其种群数量与生境面积急剧下降的物种?(2)不同的动物类群能否应用同一濒危标准尺度?(3)如何区别对待物种边缘分布区和核心分布区的种群数量与密度的差异?(4)如何处理种群的局部灭绝、局部濒危?(5)一些濒危物种在野生环境中濒危,但是这些物种可以人工繁殖,如何处理可以人工繁殖的濒危物种?(6)如果没有种群与栖息地的精确历史资料和统计数据,怎样应用物种的濒危标准评估其濒危等级?在实践中,我们针对这些问题提出了解决方案。考虑与国际流行的IUCN物种濒危等级标准接轨,我们提出来一个由“无危”、“值得关注”、“受胁”、“濒危”和“灭绝”等5个级构成的濒危等级系统,其中“值得关注”、“受胁”、“濒危”又分为“一般”与“高度”两个亚等级。我们提出应区分“生态濒危物种”、“进化濒危物种”;对于不同生物类群,应区分物种的生活史对策,制定不同生活史物种的濒危标准。对于r-对策物种,引入“经济灭绝”这一等级,将这一等级对应于“受胁”等级,以解决缺少物种数量的统计数据和历史数据这一难题;区别对待特有物种,将其濒危等级提升一等;引进集合种群(metapopulation)概念,将集合种群的局域种群(local population)作为“个体”对待。     

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.     

What cell lineages tell us about the evolution of spiralia remains to be seen

Abstract.— Cell-lineage trees may contain information about spiralian phylogeny, as proposed by Guralnick and Lind-berg (2001). Here we discuss this possibility further and conclude that the cell-division pattern must be known in greater detail and the coding methods refined before a possible phylogenetic signal can be identified.