Is black plumage an adaptation to high elevations in a cosmopolitan bird genus?

Black plumage is expected to absorb and retain more heat and provide better protection against UV radiation compared with lighter plumages. Black plumage is common in species of the genera Turdus and Platycichla that inhabit highlands across different regions of the world. Considering this geographical recurrent pattern we tested the hypothesis that black plumage in these two genera has evolved as a co‐adaptive response to inhabiting highlands, reconstructing ancestral character states for plumage and altitudinal distribution using maximum‐likelihood methods, and a Pagel's multistate discrete method. For these analyses, we used a phylogeny based on mitochondrial and nuclear DNA regions that included 60 of the 66 recognized species in the genera Turdus and Platycichla. We found that black‐plumage coloration evolved independently on eight occasions within these two genera, and species with black plumage occur more often at highlands. Our results support the hypothesis that black‐plumage is adaptative in highlands; but, studies in other bird groups with black‐plumage inhabiting at the same elevations will provide evidence for this adaptive hypothesis or if the evolution of black‐plumage in other groups is explained by other evolutionary forces.     

Life history predicts advancement of avian spring migration in response to climate change

An increasing number of studies demonstrate that plant and animal phenologies such as the timing of bird migration have been advancing over the globe, likely as a result of climate change. Even closely related species differ in their phenological responses, and the sources of this variation are poorly established. We used a large, standardized dataset of first arrival dates (FAD) of migratory birds to test the effects of phylogenetic relationships and various life-history and ecological traits on the degree to which different species adapt to climate change by earlier migration in spring. Using the phylogenetic comparative method, we found that the advancement of FAD was greater in species with more generalized diet, shorter migration distance, more broods per year, and less extensive prebreeding molt. In turn, we found little evidence that FAD trends were influenced by competition for mating (polygamy or extra-pair paternity) and breeding opportunities (cavity nests). Our findings were robust to several potentially confounding effects. These evolutionary correlations, coupled with the low levels of phylogenetic dependence we found, indicate that avian migration phenology adapts to climate change as a species-specific response. Our results suggest that the degree of this response is fundamentally shaped by constraints and selection pressures of the species' life history, and less so by the intensity of sexual selection.     

Evolution of cultural traits occurs at similar relative rates in different world regions

A fundamental issue in understanding human diversity is whether or not there are regular patterns and processes involved in cultural change. Theoretical and mathematical models of cultural evolution have been developed and are increasingly being used and assessed in empirical analyses. Here, we test the hypothesis that the rates of change of features of human socio-cultural organization are governed by general rules. One prediction of this hypothesis is that different cultural traits will tend to evolve at similar relative rates in different world regions, despite the unique historical backgrounds of groups inhabiting these regions. We used phylogenetic comparative methods and systematic cross-cultural data to assess how different socio-cultural traits changed in (i) island southeast Asia and the Pacific, and (ii) sub-Saharan Africa. The relative rates of change in these two regions are significantly correlated. Furthermore, cultural traits that are more directly related to external environmental conditions evolve more slowly than traits related to social structures. This is consistent with the idea that a form of purifying selection is acting with greater strength on these more environmentally linked traits. These results suggest that despite contingent historical events and the role of humans as active agents in the historical process, culture does indeed evolve in ways that can be predicted from general principles     

Parallel evolution of larval morphology and habitat in the snail-killing fly genus Tetanocera

In this study, we sequenced one nuclear and three mitochondrial DNA loci to construct a robust estimate of phylogeny for all available species of Tetanocera. Character optimizations suggested that aquatic habitat was the ancestral condition for Tetanocera larvae, and that there were at least three parallel transitions to terrestrial habitat, with one reversal. Maximum likelihood analyses of character state transformations showed significant correlations between habitat transitions and changes in four larval morphological characteristics (cuticular pigmentation and three characters associated with the posterior spiracular disc). We provide evidence that phylogenetic niche conservatism has been responsible for the maintenance of aquatic-associated larval morphological character states, and that concerted convergence and/or gene linkage was responsible for parallel morphological changes that were derived in conjunction with habitat transitions. These habitat-morphology associations were consistent with the action of natural selection in facilitating the morphological changes that occurred during parallel aquatic to terrestrial habitat transitions in Tetanocera.     

雀形目10种鸟类线粒体的DNA变异及分子进化

采用14种限制性内切酶（Apa I、BamHI、Bgl Ⅱ、EcoRI、EcoRV、HindⅢ、HpaI、KpnI、PstI、PuvⅡ、SalI、ScaI、XbaI和XhoI）对雀形目3科10种鸟类（蒙古百灵、喜鹊、小嘴乌雅、白腰朱顶雀、锡嘴雀、朱雀、红腹灰雀、灰腹灰雀、红交嘴雀和黄喉Wu）进行限制性片段长度多态分析（RFLP分析）。结果表明：雀形目鸟类基因组大小存在遗传多态性,不同类群在酶切类型上表现出各自的特点,雀形目鸟类与非雀形目鸟类在线粒体DNA的进化速率有着相同的特点,化石记录的地质年代与线粒体DNA分子时钟记录的年代有着惊人的吻合,这两个互为独立事件的统一,提示线粒体DNA作为分子进化的良好工具。     

安徽沿江浅水湖泊越冬水鸟群落的集团结构

长江中下游湖泊是越冬水鸟的重要栖息地,随着湖泊渔业养殖强度的不断加大,湖泊湿地严重退化,水鸟的越冬生态受到影响。为揭示长江中下游浅水湖泊越冬水鸟对湿地资源的利用特征,2008年12月至2009年3月,通过扫描取样法采集安徽省长江沿江升金湖、菜子湖和武昌湖3个浅水湖泊30种越冬水鸟的取食行为百分比数据,利用聚类分析法对越冬水鸟进行集团划分,并采用无倾向对应法(DCA)分析越冬水鸟的取食特征。聚类分析结果表明,安庆沿江湖泊越冬水鸟群落可分为4个集团,即深水取食集团G1、挖掘和啄取集团G2、浅水取食集团G3和泥滩拾取集团G4。G2集团的鸟种最多,共有13种,优势种为鸿雁(Anser cygnoides)、豆雁(Anser fabalis);G3集团次之,共6种,优势种为小天鹅(Cygnus columbianus)、白琵鹭(Platalea leucorodia);G4集团共5种,优势种为黑腹滨鹬(Calidris alpina)、鹤鹬(Tringa erythropus)和红脚鹬(Tringa totanus);G1集团水鸟种类有6种。这些水鸟的觅食生境主要在湖泊滩涂和浅水区域,其食物资源的可利用性和觅食对策共同决定群落组成结构。DCA分析表明,取食方式及取食时运动方式组成的觅食对策决定了集团食物资源的分割,草滩中取食鸟类主要采用静止取食和啄取方式,泥滩取食集团主要采取拾取及奔-停取食,深水区取食集团则主要采用潜水方式取食,因此,维持湖泊不同区域的丰富食物资源对于保护湖泊丰富的水鸟资源具有重要意义。     

Functional coupling constrains craniofacial diversification in Lake Tanganyika cichlids

Functional coupling, where a single morphological trait performs multiple functions, is a universal feature of organismal design. Theory suggests that functional coupling may constrain the rate of phenotypic evolution, yet empirical tests of this hypothesis are rare. In fish, the evolutionary transition from guarding the eggs on a sandy/rocky substrate (i.e. substrate guarding) to mouthbrooding introduces a novel function to the craniofacial system and offers an ideal opportunity to test the functional coupling hypothesis. Using a combination of geometric morphometrics and a recently developed phylogenetic comparative method, we found that head morphology evolution was 43% faster in substrate guarding species than in mouthbrooding species. Furthermore, for species in which females were solely responsible for mouthbrooding the males had a higher rate of head morphology evolution than in those with bi-parental mouthbrooding. Our results support the hypothesis that adaptations resulting in functional coupling constrain phenotypic evolution.     

Evolution and homology of bird pollination syndromes in Erythrina (Leguminosae)

Erythrina L. (Leguminosae: Phaseoleae) is a pantropical genus of over 100 species, all of which are either hummingbird or passerine pollinated. Phylogenetic hypotheses based on morphological and chloroplast DNA restriction site characters suggest that shifts from passerine to hummingbird pollination have occurred a minimum of four times in the genus. In hummingbird-pollinated species the inflorescences are held upright, the flowers are arranged radially along the axis, and the narrow standard petal is conduplicately folded to form a pseudotube. In most of the passerine-pollinated species, the inflorescences are held horizontally, the flowers are secund, and the standard petal is open so that the nectar and androecium are easily visible and accessible. Nectar amino acid concentrations and sucrose to hexose ratios are closely associated with pollination mode. Despite the general resemblance in flower and inflorescence morphology among species with the same pollination type, homology assessment reveals that petal morphology and size, and calyx and pollen morphology differ. Morphological characters, even if comprising modifications associated with adaptive pollination systems, therefore provide useful phylogenetic information.