The future of human being may rely on biodiversity, and thus depends on how to investigate, conserve, and rationally use biodiversity. Species is the basic unit of biodiversity, and therefore rational delimitation of species is one of the crucial issues for biodiversity pursuits. However, no species concept published until now is both scientific and operative. A tentative species concept is proposed here just for discussion.

One of the diverse species concepts defined before may only perceive one aspect of the mature species like “the blind men feel the elephant” while the mature species at the final speciation stage should have integrated all species concepts. Most “species” in the nature are on the way to the final speciation stage. However, before reaching the final speciation stage, these species undertake further cycles of speciation. Species from the repeated splits of the incomplete divergences show incomplete reproductive isolations, frequent interspecific gene flow and reticulate evolutions. In addition, the earliest divergent gene differs between different pairs of species. Therefore, the divergence orders for different species concepts vary greatly between organisms. Such random divergences lead to the extreme difficulty to define a common and accurate species concept for all “species” on the speciation way. It is better to delimitate species, publish new species and conduct taxonomic revisions based on conditions and approaches of as many species concepts as possible. In addition, incomplete reproductive isolations, limited interspecific gene flow and some ‘abnormal’ individuals not ascribed to any species due to interspecific hybridizations and within-population mutations should be widely acknowledged during species delimitations. Such circumscribed species may be more objective and scientific than previously delimitated based only on one single species concept.

Biologists believe that species is the basic unit of biological diversity, and few people will doubt the fact that there exist distinct species in nature. Nevertheless, despite of ceaseless debating on species concept or species definition among biologists over nearly a century, no consensus has been reached. Species definition concerns many biologists because it has far-reaching practical implications. Therefore, species concepts proposed by various scholars zero in greatly on their operational convenience and practical applicability in research activity such as taxonomic classification. As a result, these concepts and definitions are unavoidably shaped by the visions of the scholars which are further shaped by their insights into the evolutionary process of speciation. Speciation represents a stage in evolutionary divergence, and also different “species” may be at different stages of the speciation process. Since a “definition” is a kind of convention or confining description, every definition would bear some limitations. It would be thus very difficult, if not impossible, to define a perfect species concept that will accord with all species in taxonomic practice. From this perspective, we should confess that while every species concept or definition proposed thus far is reasonable, none is faultless or flawless. It is very important to bear this in mind, because, otherwise, one may stubbornly insist on one single species concept and introduces errors or even triggers chaos and confusion, consciously or unconsciously, in taxonomic and other evolutionary researches.

This is a mini-review on the historical changes in the concept of species. Biologists use different methods or criteria to discriminate species, leading to the formation of different species concepts, e.g. biological species, morphospecies, ecological species, evolutionary species, phylogenetic/cladistic species, or their combinations. These concepts respectively reveal a specific profile of the species’ attributes, as well as reflecting the objective existence of these creatures as different species, but not being satisfied with everyone. For eukaryotes, reproductive isolation (incapable of reproducing fertile offspring) should be the key for two populations to differentiate into two different species, no matter how much they differ morphologically. The mechanisms underlying such isolation might be geographical, behavioral, or otherwise. Reproductive isolation is certainly accompanied by some morphological or genetic changes that are often used as criteria by taxonomists or molecular evolutionary biologists to distinguish species, although these attributes may not be associated with reproductive isolation itself. Extinct species known only from fossils are impossible to be classified taxonomically according to reproductive isolation. The exact definition of the term “species” is still controversial, as a species concept based on reproductive isolation is usually not applicable, but a usable species definition (e.g. morphospecies) is regarded to be artificial.

Both species concept and recognition are fundamental topics in the studies of taxonomy and biodiversity, and also in biological researches. There has never been any unanimous and clear standard for species dilimitation and, thus, taxonomy has more or less been regarded as subjective and often seen as art rather than scientific research. The backgrounds and the current status of three commonly used species concepts, i.e. morphological, biological and phylogenetic species concepts, in the research of fungal taxonomy are briefly reviewed here. The application of the three species concepts are discussed with examples in fungal taxonomy, especially on interlaces and incongruences between the concepts. The materials presented here may provide some useful information for the study on taxonomy and the investigation on species concept.

Very recently, Professor Deyuan Hong, the editor-in-chief of the ongoing Flora of Pan-Himalaya, put forward a series of proposals (which may be conveniently termed Hong’s Ten Points) on raising rationality in species delimitation, a hotly-debated question in systematic biology [Hong DY (2016) Opinion on raising rationality in species delimitation. Biodiversity Science, 24: 360-361]. The present paper is mainly to expound on some of the points. Even after the Flora Reipublicae Popularis Sinicae and its English version, Flora of China, was published, many species-level taxonomic problems of plants from China still remain to be solved. This situation may be due in part to previous unsatisfactory taxonomic practice and in part to our poor knowledge of taxonomic characters of a large number of plant groups from the country. Indeed, a very important stage in plant taxonomy, the biosystematic phase, was basically missing in China, and even the consolidation or systematic phase (one of the stages in alpha-taxonomy) has not yet been accomplished for some groups. Nowadays, it is inappropriate to emphasize the separation of orthodox and experimental taxonomy, and a multidisciplinary approach needs to be adopted in addressing taxonomic problems. To gain a fuller understanding of plant biodiversity in China, creative monographic work is badly needed, which requires the training of young botanical monographers. Moreover, it is suggested that practicing taxonomists should take extreme caution when employing population concept and statistical methods in their routine work. Finally, it is argued that every effort should be made toward a broader biological species concept although botanists have to accept the pluralism in species concept. To revert to a purely subjective species concept, under the pretext of the existence of the so-called lumpers or splitters in systematic biology, is not correct and must be opposed.

Bed-site selection is the behavioral adaptation of wild animals to their ecological environment. In this study, we explored the seasonal variation of nocturnal bed-site characteristics by Milu (Elaphurus davidianus, Père David’s deer). We used direct and track observation methods to assess nocturnal bed-site selection over different seasons (November 2013 to December 2014) by Milu in Hubei Shishou Milu National Nature Reserve, China. We recorded the ecological characteristics of 184 nocturnal bed-site plots and 184 control plots. Results showed that Milu preferred bed-sites with greater woodland cover, a greater proportion of vegetation, abundant food resources, and proximity to shelter (reeds or woods) during spring, autumn and winter (P < 0.05). Moreover, differences in distance to roads and to human settlements in bed-sites selection were not significantly different (P > 0.05) during spring and autumn. In summer, the Milu population preferred bedding on bare ground characterized by a low hiding cover, higher herbage coverage, lower food abundance, close proximity to hide and water, and an increased distance to road and human settlement (P < 0.05). This is in contrast to winter, as the Milu population preferred bed-sites with lower wind speeds that were closer to roads and human settlements (P < 0.05). Stepwise discriminant analysis indicated that seasonal nocturnal bed-site selection by the Milu population could be discriminated with three canonical discriminant functions. A Fisher discriminant function composed of herbage coverage, food abundance, hiding cover, wind speed, and distance to hide and water could discriminate the seasonal nocturnal bed-site of the Milu population. The characteristics of bed-sites selected by Milu in different seasons had some similarities and differences, most likely as a result of food, water, temperature, and anthropogenic interference. On the basis of our findings, we suggest to expand supplementary feed base, to retain vegetation that provide adequate cover for Milu, to reduce anthropogenic interference and to regulate water levels in the oxbow around the nature reserve for the conservation of Milu in this area.

Geographical variation of body color is widely present in reptile populations that survive in different substrate habitats, multiple potential mechanisms can account for this color variation. Phrynocephalus versicolor and P. frontalis, close genetic relatives, constitute a phylogenetic species group together with P. przewalskii. In this study, a fiber spectrophotometer (AvaSpec-2048) was used to record the skin luminous reflectivity of 12 sites across the lizard’s body, and we quantitatively compared the natural color variation of dark P. versicolor and light P. frontalis that lived in “melanistic” and “non-melanistic” habitats, respectively. We aimed to determine whether the color variations of both populations were time reversible, and further discuss potential mechanisms that substrate color may have on color variation of Phrynocephalus lizards. Our results showed that the body color of P. versicolor in “melanistic” habitat was significantly darker than P. frontalis in the “non-melanistic” withered yellow habitat. We also conducted a reciprocal transplantation experiments (i.e. “non-melanistic” withered yellow P. frontalis individuals were transplanted and fed in “melanistic” substrate environment, while “melanistic” P. versicolor individuals were transplanted and fed in withered yellow substrate environment). For “melanistic” P. versicolor, the skin reflectivity of six sites increased significantly after one week, while no significant changes were detected in other sites. For “non-melanistic” P. frontalis, except the skin reflectivity of two sites (left hind limb and top right on the back) significantly changed, compared to corresponding values one week previously, other sites showed no significant changes. Our results suggest that P. versicolor possesses stronger color variation ability than P. frontalis, and the color phenotypes are likely inherited in both species. Short-term changes of substrate color can cause slightly color variations that are difficult to distinguish by naked eyes, suggesting ontogeny related hereditary factors may also play a controlling role.

Based on biological and environmental materials collected during May and September of 2011, the composition of macrozoobenthos functional feeding groups was analyzed. Meanwhile, the feeding evenness index calculated from biomass data, together with M-bAMBI erected using biomass data, were used to assess the ecological quality of Bohai Bay for the first time. Results showed that the macrozoobenthos community was divided into five feeding groups, including a carnivorous group (CA), omnivorous group (OM), planktivorous group (PL), herbivorous group (HE) and detritivorous group (DE). Except for group HE, the other four groups were all sampled in the study area. Groups PL and OM displayed the greatest percentages of community average biomass in both voyages and the group DE displayed the smallest percentage. Cluster analysis indicated that the composition of the macrozoobenthos feeding group in the Haihe Estuary was significantly different from other areas. The risk index (RI) values were relatively lower in the Haihe Estuary than the other areas in the study region. Meanwhile, an obvious spatial gradient was observed along the Haihe estuary towards the offshore area during May 2011. The average feeding evenness index value was 0.28 indicating poor ecological quality in most study areas. In addition, the lower bj_FD values were found in the Haihe Estuary, Beitang outlet and their surrounding areas, which was similar to the RI spatial pattern. BEST analysis indicated that temperature, salinity, heavy metals, and nutrients were the main environmental factors affecting the feeding evenness index. Compared with the M-bAMBI, bj_FD was more sensitive to the poor environmental quality status of the Haihe Estuary and Beitang outlet. In general, bj_FD could be used to evaluate the ecological quality of Bohai Bay.

Differences in fitness between two species or genotypes is usually assumed to be constant when competition experiments are used to measure relative fitness in evolutionary experiments. However, interactions between competitors may lead to frequency-dependence in fitness. We measured the relative fitness of two types of evolved lines of Escherichia coli under different initial relative frequencies to analyze the effects of initial relative frequency on relative fitness. Competed with the low nitrogen evolved lines, the high nitrogen evolved lines displayed increased relative fitness with decreased initial relative frequency, which suggests negative frequency dependence. Both types did not grow in the filtrate from high nitrogen evolved lines, but grew in the filtrate from low nitrogen evolved lines. However, the number of cell doublings of the high nitrogen evolved lines was three times higher than that of the low nitrogen evolved lines. One probable explanation for the negative frequency dependent fitness was that the low nitrogen evolved lines had weaker resource competitive ability and could not sufficiently use resources. Another explanation was that the high nitrogen evolved lines could use some metabolites produced by the low nitrogen evolved lines, which suggests the existence of cross-feeding interaction. Different interactions may lead to different relationships between relative fitness and initial relative frequency. Therefore, we need to account for the effects of initial relative frequency on relative fitness to more accurately measure fitness in evolutionary experiments.

It is well known that the leaves of many woody plant species flush red rather than green during particular stages across their life span. Non-green leaf coloration caused by active synthesis of anthocyanin in plant organs at these stages costs the plant significant resources and energy, resulting in a reduction of primary photosynthesis. Therefore, it is likely that the coloration change is an active process and not simply a by-product of metabolism. Various hypotheses formulated to explain the potential reasons for coloration change can be divided into two categories: (1) those that suggest it is physiological adaptation for resistance to severe environments (high light, drought and low temperatures); and (2) those that suggest it protects against herbivory damage (coevolution, unpalatability, camouflage and anticamouflage, etc.). To date, there is no consensus on the relative validity of these ideas. The majority of previous work has focused on only a few species and autumn leaf color change. The relatively few studies done on red young leaves in spring mostly focused on red coloration as an independent visual signal. Future studies need to consider the chemical and mechanical defense of leaf redness, as well as the anthocyanins presented in other plant organs (thorns, stems and particularly, flowers), which may experience similar selection as leaves. The quantification of environmental factors and herbivore selection would be helpful in expansion our understanding in young leaf redness.

Rock-inhabiting fungi (RIF) are peculiar organisms with high diversity that apparently lack sexual reproductive structures and form compact, melanised colonies on bare rock surfaces. These fungi are one of the most stress-tolerant eukaryotic life forms on the earth and have evolved a variety of adaptive mechanisms to occupy harsh niches. They also have special characteristics related to their cell structure, metabolism, and stress tolerance mechanisms. Although RIF are very ubiquitous, they have often been overlooked due to their small size, slow growth and lack of diagnostic features. In this review, we describe the diversity, research approaches, history, adaptive mechanism and applied research of rock-inhabiting fungi, to focus attention on RIF and their importance.

Pollination is an important ecosystem services closely related to grain products and food security. Recent research has shown that pollinator declines directly affect human wellbeing, which has attracted widespread attention from the global community. Fittingly, the “pollinator, pollination and food production assessment” was listed as a high priority rapid assessment in 2014-2018 work programme of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES). The summary for policymakers was adopted at the fourth plenary meeting of IPBES. Within the IPBES framework, we introduce the start point and main contents of the thematic assessment report and explored the relationship between this assessment and other processes and its potential impacts. We also analyze what was learned and current shortcomings. We propose the following actions: (1) to survey pollinator diversity and to assess the value of pollination services; (2) to establish pollination monitoring system; (3) to analyze the risk factors and formulate pollinator conservation and restoration activities; (4) to optimize farming modes and to enhance policy support; and (5) to expand publicity and increase public participation.