Why the leopard got its spots: relating pattern development to ecology in felids

A complete explanation of the diversity of animal colour patterns requires an understanding of both the developmental mechanisms generating them and their adaptive value. However, only two previous studies, which involved computer-generated evolving prey, have attempted to make this link. This study examines variation in the camouflage patterns displayed on the flanks of many felids. After controlling for the effects of shared ancestry using a fully resolved molecular phylogeny, this study shows how phenotypes from plausible felid coat pattern generation mechanisms relate to ecology. We found that likelihood of patterning and pattern attributes, such as complexity and irregularity, were related to felids' habitats, arboreality and nocturnality. Our analysis also indicates that disruptive selection is a likely explanation for the prevalence of melanistic forms in Felidae. Furthermore, we show that there is little phylogenetic signal in the visual appearance of felid patterning, indicating that camouflage adapts to ecology over relatively short time scales. Our method could be applied to any taxon with colour patterns that can reasonably be matched to reaction-diffusion and similar models, where the kinetics of the reaction between two or more initially randomly dispersed morphogens determines the outcome of pattern development.     

哺乳动物毛色调控机制及其适应性进化研究进展

哺乳动物类群呈现出的丰富毛色是引人注目的一种生物现象,是研究和理解哺乳动物适应性进化的理想模型之一。哺乳动物的毛色多态在躲避天敌、捕食、求偶及抵御紫外线等方面都具有重要作用。哺乳动物毛发的色素化过程由体内黑色素的数量、质量和分布状况所决定。黑色素的形成过程复杂,包括黑素细胞的分化、成熟,黑素体等细胞器的形态发生及黑色素在黑素细胞中的合成代谢和转运等过程;而在细胞色素化的每个阶段/时相都伴随着一些重要功能基因的参与,并通过基因之间的相互作用形成了黑色素生物代谢的复杂调控网络,进而形成不同的毛色有助于哺乳动物适应不同生存环境。对哺乳动物不同毛色形成机制的探究一直以来都是遗传学及进化生物学的重要研究领域和聚焦热点。本文综述了哺乳动物毛色色素化过程的主要分子机制以及毛色适应性进化的遗传基础,以期为哺乳动物毛色多态及其适应性进化的分子机制研究提供参考。     

马毛色遗传机理研究进展

动物毛色是人类正向选择产生的表型之一,在遗传与进化过程中扮演着重要角色。其中马的毛色丰富多变,单从表型无法准确判别其属于哪种毛色,造成马品种登记时毛色性状记录不准确,因此研究马毛色形成机理在育种工作中具有重要意义。随着基因组学及测序技术的日益成熟,马毛色形成遗传机理的研究不断深入,并发现不同毛色性状与特定疾病之间的相关性。本文从遗传学的角度对马的毛色进行归类,对与其形成的相关基因、作用机理及应用等研究进展进行了综述,以期为马毛色形成机理的系统性研究和马匹选育提供借鉴和参考。     

Ecology and status of the jaguarundi Puma yagouaroundi: a synthesis of existing knowledge

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Morphological patterns in the skulls of cats

Measurements on the skull and dentition of 159 specimens of 22 species of recent felid were analysed using multivariate statistical methods (principal components analysis and correspondence analysis). The resulting patterns were considered in the light of recent work on the systematics of felids (large cats and small cats were clearly differentiated). Within each group there are subgroups. In the small cat group one subgroup was found to consist of the species Lynx lynx, L. rufus, L. pardina, L. canadensis and possibly Felis manul. Another subgroup consisted of the species F. bengalensis, F. rubiginosa, F. planiceps and F. viverrina. These two subgroups agree well with other work on felid systematics. Subgroups which do not agree so well with other work were also found, and the reasons for this are considered. Within the large cats there are two species, F. concolor and Neofelis nebulosa , which are clearly deviant from the norm. The reasons for this deviation are also considered.     

Reproductive biology of the 38 extant felid species: a review

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How the pterosaur got its wings

Throughout the evolutionary history of life, only three vertebrate lineages took to the air by acquiring a body plan suitable for powered flight: birds, bats, and pterosaurs. Because pterosaurs were the earliest vertebrate lineage capable of powered flight and included the largest volant animal in the history of the earth, understanding how they evolved their flight apparatus, the wing, is an important issue in evolutionary biology. Herein, I speculate on the potential basis of pterosaur wing evolution using recent advances in the developmental biology of flying and non‐flying vertebrates. The most significant morphological features of pterosaur wings are: (i) a disproportionately elongated fourth finger, and (ii) a wing membrane called the brachiopatagium, which stretches from the posterior surface of the arm and elongated fourth finger to the anterior surface of the leg. At limb‐forming stages of pterosaur embryos, the zone of polarizing activity (ZPA) cells, from which the fourth finger eventually differentiates, could up‐regulate, restrict, and prolong expression of 5′‐located Homeobox D (Hoxd) genes (e.g. Hoxd11, Hoxd12, and Hoxd13) around the ZPA through pterosaur‐specific exploitation of sonic hedgehog (SHH) signalling. 5′Hoxd genes could then influence downstream bone morphogenetic protein (BMP) signalling to facilitate chondrocyte proliferation in long bones. Potential expression of Fgf10 and Tbx3 in the primordium of the brachiopatagium formed posterior to the forelimb bud might also facilitate elongation of the phalanges of the fourth finger. To establish the flight‐adapted musculoskeletal morphology shared by all volant vertebrates, pterosaurs probably underwent regulatory changes in the expression of genes controlling forelimb and pectoral girdle musculoskeletal development (e.g. Tbx5), as well as certain changes in the mode of cell–cell interactions between muscular and connective tissues in the early phase of their evolution. Developmental data now accumulating for extant vertebrate taxa could be helpful in understanding the cellular and molecular mechanisms of body‐plan evolution in extinct vertebrates as well as extant vertebrates with unique morphology whose embryonic materials are hard to obtain.     

Spots, stripes, tail tips and dark eyes: Predicting the function of carnivore colour patterns using the comparative method

Animal colour patterns are adaptive for three reasons: camouflage, communication and physico-physiological functions. This study proposes a conceptual framework for predicting the main adaptive function of carnivore colour patterns based on three factors: visibility, shape and location on the body, as well as, their behavioural ecological correlates. Using a comparative phylogenetic approach, the colour patterns present on the body, the tail and the eyes of 200 species of mammalian carnivores were analysed. Their evolutionary history was reconstructed using MacClade and Maddison's concentrated-changes test was used to test the association between species' colour patterns and their behavioural ecology on a composite phylogeny for all the Carnivora. The results for dark spots, vertical stripes, horizontal stripes, ringed tails, black tail tips, white tail tips, dark eye contour and dark eye patches, are presented. The comparative analyses indicate that spotted, vertically striped and horizontally striped coats evolved for camouflage. Tail markings seem to have evolved for intra- and/or inter-specific communication, while dark markings near and around the eyes are associated with variables consistent with a physico-physiological function. These findings suggest that both the physical environment and animal behaviour are important selective factors driving the evolution of animal colour patterns and that both need to be taken into consideration in future studies of animal coloration.     

How the mollusc got its scales: convergent evolution of the molluscan scleritome

Radiation of dramatically disparate forms among the phylum Mollusca remains a key question in metazoan evolution, and requires careful evaluation of homology of hard parts throughout the deep fossil record. Enigmatic early Cambrian taxa such as Halkieria and Wiwaxia (in the clade Halwaxiida) have been proposed to represent stem‐group aculiferan molluscs (Caudofoveata + Solenogastres + Polyplacophora), as complex scleritomes were considered to be unique to aculiferans among extant molluscs. The ‘scaly‐foot gastropod’ (Neomphalina: Peltospiridae) from hydrothermal vents of the Indian Ocean, however, also carries dermal sclerites and thus challenges this inferred homology. Despite superficial similarities to various mollusc sclerites, the scaly‐foot gastropod sclerites are secreted in layers covering outpockets of epithelium and are largely proteinaceous, while chiton (Polyplacophora: Chitonida) sclerites are secreted to fill an invaginated cuticular chamber and are largely calcareous. Marked differences in the underlying epithelium of the scaly‐foot gastropod sclerites and operculum suggest that the sclerites do not originate from multiplication of the operculum. This convergence in different classes highlights the ability of molluscs to adapt mineralized dermal structures, as supported by the extensive early fossil record of molluscs with scleritomes. Sclerites of halwaxiids are morphologically variable, undermining the assumed affinity of specific taxa with chitons, or the larger putative clade Aculifera. Comparisons with independently derived similar structures in living molluscs are essential for determining homology among fossils and their position with respect to the enigmatic evolution of molluscan shell forms in deep time. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 949–954.     

Parasite histories and novel phylogenetic tools: alternative approaches to inferring parasite evolution from molecular markers

Parasitological research is often contingent on the knowledge of the phylogeny/genealogy of the studied group. Although molecular phylogenetics has proved to be a powerful tool in such investigations, its application in the traditional fashion, based on a tree inference from the primary nucleotide sequences may, in many cases, be insufficient or even improper. These limitations are due to a number of factors, such as a scarcity/ambiguity of phylogenetic information in the sequences, an intricacy of gene relationships at low phylogenetic levels, or a lack of criteria when deciding among several competing coevolutionary scenarios. With respect to the importance of a precise and reliable phylogenetic background in many biological studies, attempts are being made to extend molecular phylogenetics with a variety of new data sources and methodologies. In this review, selected approaches potentially applicable to parasitological research are presented and their advantages as well as drawbacks are discussed. These issues include the usage of idiosyncratic markers (unique features with presumably low probability of homoplasy), such as insertion of mobile elements, gene rearrangements and secondary structure features; the problem of ancestral polymorphism and reticulate relationships at low phylogenetic levels; and the utility of a molecular clock to facilitate discrimination among alternative scenarios in host-parasite coevolution.     

How plants conquered land: evolution of terrestrial adaptation

The transition of plants from water to land is considered one of the most significant events in the evolution of life on Earth. The colonization of land by plants, accompanied by their morphological, physiological and developmental changes, resulted in plant biodiversity. Besides significantly influencing oxygen levels in the air and on land, plants manufacture organic matter from CO₂ and water with the help of sunlight, paving the way for the diversification of nonplant lineages ranging from microscopic organisms to animals. Land plants regulate the climate by adjusting total biomass and energy flow. At the genetic level, these innovations are achieved through the rearrangement of pre-existing genetic information. Advances in genome sequencing technology are revamping our understanding of plant evolution. This study highlights the morphological and genomic innovations that allow plants to integrate life on Earth.     

Social evolution in the genusHalictus: a phylogenetic approach

Summary Halictine bees exhibit an enormous diversity of solitary and social colony structures. To investigate social evolution in the genusHalictus, phylogenies of 15 species of the subgeneraH. (Halictus) andH. (Seladonia) were constructed based on protein electrophoretic data. Solitary, social, and socially polymorphic species were included.Halictus (Seladonia) apparently rendersH. (Halictus) paraphyletic. The common ancestor ofH. (Halictus) andH. (Seladonia) was probably social or socially polymorphic. This implies that some solitary and socially polymorphic species, such asH. confusus andH. tumulorum, represent evolutionary reversals from a completely eusocial condition to the solitary condition that is thought to be primitive for the subfamily as a whole.     

Ecological niche differentiation in the Aphelocoma jays: a phylogenetic perspective

The Aphelocoma jays have become an important touchstone in behavioural ecology and biogeography – the corpus of studies of this genus makes it an important point of reference. Aphelocoma evolutionary history, nevertheless, has been the subject of two papers reaching opposite conclusions, even though they were based on the same allozyme data set. Herein, we present a second molecular data set – 500 bases of the ND2 gene – and analyse it cladistically to arrive at a new hypothesis of phylogenetic relationships. Recent hypotheses by other investigators of a hybrid origin of Aphelocoma populations are strongly contradicted. The ecological context within which these evolutionary processes are taking place is characterized using new tools for modelling ecological niches of species along a spectrum from humid tropical to dry temperate habitats. Evolutionary patterns of ecological niches are shown to consist of drastic departures from rate-uniformity and ecological niche conservatism.  © 2003 The Linnean Society of London, Biological Journal of the Linnean Society , 2003, 80 , 369–383.     

The evolution of bat pollination: a phylogenetic perspective

Background

Most tropical and subtropical plants are biotically pollinated, and insects are the major pollinators. A small but ecologically and economically important group of plants classified in 28 orders, 67 families and about 528 species of angiosperms are pollinated by nectar-feeding bats. From a phylogenetic perspective this is a derived pollination mode involving a relatively large and energetically expensive pollinator. Here its ecological and evolutionary consequences are explored.

Scope and Conclusions

This review summarizes adaptations in bats and plants that facilitate this interaction and discusses the evolution of bat pollination from a plant phylogenetic perspective. Two families of bats contain specialized flower visitors, one in the Old World and one in the New World. Adaptation to pollination by bats has evolved independently many times from a variety of ancestral conditions, including insect-, bird- and non-volant mammal-pollination. Bat pollination predominates in very few families but is relatively common in certain angiosperm subfamilies and tribes. We propose that flower-visiting bats provide two important benefits to plants: they deposit large amounts of pollen and a variety of pollen genotypes on plant stigmas and, compared with many other pollinators, they are long-distance pollen dispersers. Bat pollination tends to occur in plants that occur in low densities and in lineages producing large flowers. In highly fragmented tropical habitats, nectar bats play an important role in maintaining the genetic continuity of plant populations and thus have considerable conservation value.     

基于红外相机数据评估华南地区豹猫的种群密度和活动节律

可靠的种群密度数据对野生动物的保护和管理十分重要。豹猫(Prionailurus bengalensis)是中国分布最广且常见的猫科动物, 但野生种群密度估算的研究并不多。本研究于2020年6月至2021年5月在香港新界嘉道理农场暨植物园开展红外相机调查, 利用空间标记-重捕法估算当地豹猫的种群密度并用核密度估计方法分析其活动节律。本次调查以网格方式布置红外相机, 在约1.5 km²的研究范围之内设置了19个相机位点, 每个位点安装2台相机以获取豹猫身体两侧花纹来进行个体识别。连续12个月调查共捕获113次有效的豹猫拍摄事件, 当中仅61次事件的照片足够清晰以进行个体识别。基于种群封闭的要求, 我们以2个月为单位将12个月的数据分为6个采样期去分析豹猫种群密度, 结果显示仅两个采样期的估算值最为准确, 分别为0.64 ± 0.31 (0.26-1.55)只/km²和0.87 ± 0.48 (0.31-2.40)只/km², 是已知全球豹猫密度最高的地点之一。结果还发现, 雨季研究地点的豹猫并无明显的日活动节律, 在旱季则偏夜行-晨昏行性多一些, 但也有一定的日间活动; 雨季和旱季的日活动节律无显著差异。本研究是首次以个体识别配以空间标记-重捕模型对中国大陆地区豹猫种群密度调查的研究; 我们也提出一些关于红外相机架设方法的建议, 以提高照片个体识别的准确度并增加重捕次数, 最后提高密度估算的准确度。本研究也进一步证明豹猫适应性极强, 在活动节律上表现出极高的可塑性, 在严格保护下可以恢复健康的种群。     

Dynamics of the evolution of Batesian mimicry: molecular phylogenetic analysis of ant-mimicking Myrmarachne (Araneae: Salticidae) species and their ant models

Batesian mimicry is seen as an example of evolution by natural selection, with predation as the main driving force. The mimic is under selective pressure to resemble its model, whereas it is disadvantageous for the model to be associated with the palatable mimic. In consequence one might expect there to be an evolutionary arms race, similar to the one involving host-parasite coevolution. In this study, the evolutionary dynamics of a Batesian mimicry system of model ants and ant-mimicking salticids is investigated by comparing the phylogenies of the two groups. Although Batesian mimics are expected to coevolve with their models, we found the phylogenetic patterns of the models and the mimics to be indicative of adaptive radiation by the mimic rather than co-speciation between the mimic and the model. This shows that there is strong selection pressure on Myrmarachne, leading to a high degree of polymorphism. There is also evidence of sympatric speciation in Myrmarachne, the reproductive isolation possibly driven by female mate choice in polymorphic species.     

Large-scale phylogenetic analysis provides insights into the diversification and evolution of sessilid peritrich ciliates (Protista: Ciliophora)

The Peritrichia is a speciose and morphologically distinctive assemblage of ciliated protists that was first observed by Antonie van Leeuwenhoek over 340 years ago. In the last two decades, the phylogenetic relationships of this group have been increasingly debated as morphological and molecular analyses have generated contrasting conclusions, mainly owing to limited sampling. In the present study, we performed expanded phylogenetic analyses of 152 sessilid peritrichs collected from 14 different provinces of China and 141 SSU rDNA peritrich sequences from GenBank. The results of the analyses revealed new divergent relationships between and within major clades that challenge the morphological classification of this group including, (1) the recovery of four major phylogenetically divergent clades in the monophyletic order Sessilida, (2) aboral structures such as the stalk and spasmoneme were evolutionary labile, (3) the stalk or/and spasmoneme was lost in each divergent clade indicating that parallel evolution occurred in sessilid peritrichs and (4) the life cycle and habit drive the diversity of aboral structures as well as diversification and evolution in peritrichs.