Eusociality and the success of the termites: insights from a supertree of dictyopteran families

Sociality in insects may negatively impact on species richness. We tested whether termites have experienced shifts in diversification rates through time. Supertree methods were used to synthesize family‐level relationships within termites, cockroaches and mantids. A deep positive shift in diversification rate is found within termites, but not in the cockroaches from which they evolved. The shift is responsible for most of their extant species richness suggesting that eusociality is not necessarily detrimental to species richness, and may sometimes have a positive effect. Mechanistic studies of speciation and extinction in eusocial insects are advocated.     

Comparison of reptile sampling in Iran with pitfall versus double-ended funnel traps

In north Khorasan province, Iran, we compared the effectiveness of two types of traps for collecting reptiles: funnel traps and pitfall traps. Three stations were monitored over three 10-day periods and in total 544 individuals (including 200 recaptures) belonging to 5 species and 4 families of lizards (Lacertidae) were collected. Funnel traps with 280 captures were more efficient than pitfall traps with 264 captures, but the differences between the two traps are not significant. Three species were captured most often in the three different stations respectively: station 1, Bunopus crassicauda (22% relative frequency); station 2, Eremias fasciata (29% relative frequency); and station 3, Trapelus agilis (32% relative frequency). Shannon species richness indices were higher for pitfall than funnel traps (i.e., 1.45 vs. 1.40), but the difference was not significant. Pitfall traps were better for capturing species that search widely for food, while the funnel traps preferentially captured species that climb plants, such as Trapelus agilis. We recommend using both types of trap to capture the various types of species in any one region.     

Observations on the relation between phytoplankton diversity and environmental factors in the Vaal River at Balkfontein,South Africa

The relationship between specific environmental factors as independent variables and temporal changes in phytoplankton community structure in the Vaal River (a turbid system) during 1984 was investigated by employing different diversity indices. Temporal changes in community structure reflected temporal changes in certain environmental factors. Phytoplankton diversity, measured with Shannon-Wie H' and Hurlbert PIE indices, was related firstly to discharge and discharge derived variables (such as SO₄, Si, N and P loading) and secondly to turbidity derived variables (such as euphotic zone depth). Discharge appears to be of prime importance in affecting diversity. Observations were made that shed new light on conditions contributing to the development of an August peak (dominated by Stephanodiscus hantzschii fo. tenuis and Micractinium pusillum) in phytoplankton concentration. Increased environmental stress may reduce the number of sensitive species, thus reducing interspecific competition between tolerant species which could then exploit the — for them — more favourable conditions resulting in an increase in their numbers to peak concentrations.     

Global diversity and adaptations of avian eggshell thickness indices

The amniote eggshell is a fundamental aspect of the embryo life-support system, protecting it from UV light, microbes and mechanical damage, while regulating gas exchange and providing calcium for growth. The thickness of eggshells is highly diverse across modern birds and influences multiple eggshell functions, yet the selective pressures driving eggshell thickness have not been clearly identified. Here, we use a global dataset of avian eggshell thickness indices for 4260 (> 41%) avian species to assess trends in eggshell thickness across the phylogeny, as these indices are strongly correlated with direct measures of eggshell thickness and are non-destructive to the sample. We analysed the dataset within a phylogenetic framework to assess the relative importance of climatic and ecological explanations for variation in eggshell thickness indices. The distribution of avian eggshell thickness indices across species was found to be primarily driven by phylogenetic relatedness, in addition to evolutionary processes that do not match a Brownian model of evolution. Across modern birds, thicker eggshells were more prevalent in species (1) with precocial young, (2) which exhibit a scavenger-based diet, (3) which primarily feed on vertebrates or plants (excluding nectivores, seed and fruit specialists) and (4) which breed in open habitats. Thicker eggshells found in species with precocial young probably enable higher rates of calcium removal for the more advanced embryo development. Excessive light transmission through the shell damages developing embryos, while too little light transmission can impede development. Eggs in shaded habitats experience low light exposure, and thus thinner shells are more prevalent in these environments potentially to increase light transmission through the shell. Overall, variation in eggshell thickness indices appears to be driven largely by phylogeny, with certain life-history traits linked to embryo growth rate, calcium content of their food, and the need to mitigate excessive light transmission through the shell.     

Species richness of sawfly–host plant associations at higher taxonomic levels

Insect–plant interactions are important to understanding the evolutionary mechanisms responsible for most of the diverse plant‐feeding insects. We aggregated data on sawfly–host plant associations and other resource associations from existing sources to address the following questions: (i) Is there a general correlation between host diversity and sawfly species richness? (ii) Is the pattern of host plant use consistent across sawfly lineages? and (iii) Is there a phylogenetically significant shift in species richness among sawflies? Our analysis comprised 8567 sawfly species, including 2087 species with host plant and other records. In total, there were 2126 records of host usage for sawflies, the overwhelming majority of which were sawflies using angiosperms as resources. Rosales are used by most of the species in sawfly families or subfamilies. We found that there was a strong correlation between the number of host plant orders and the species richness of sawfly families and subfamilies. To examine the points at which sawflies have experienced significant shifts in species richness, we compared sister taxon species richness. Several positive and negative shifts in species richness among sawflies were related to their range of host plant usage and specialized niche, respectively. In general, we found that most of the sawfly families and subfamilies used several orders as host plants, but mainly core eudicots, although some families or subfamilies were specialized on pteridophytes or gymnosperms.     

Determining the relative roles of species replacement and species richness differences in generating beta‐diversity patterns

Aim To determine the relative contribution of species replacement and species richness differences to the emergence of beta‐diversity patterns. Innovation A novel method that disentangles all compositional differences (β_cc, overall beta diversity) in its two components, species replacement (β_‐3) and species richness differences (β_rich) is proposed. The performance of the method was studied with ternary plots, which allow visualization of the influence of the relative proportions of shared and unique species of two sites over each metric. The method was also tested in different hypothetical gradients and with real datasets. The novel method was compared with a previous proposal based on the partitioning of overall compositional differences (β_sor) in replacement (β_sim) and nestedness (β_nes). The linear response of β_cc contrasts with the curvilinear response of β_sor to linear gradients of dissimilarity. When two sites did not share any species, β_sim was always 1 and β_‐3 only reached 1 when the number of exclusive species of both sites was equal. β_‐3 remained constant along gradients of richness differences with constant replacement, while β_sim decreased. β_rich had a linear response to a linear gradient of richness differences with constant species replacement, whereas β_nes exhibited a hump‐shaped response. Moreover, β_sim > β_nes when clearly almost all species of one site were lost, whereas β_‐3 < β_rich in the same circumstances. Main conclusions The behaviour of the partition of β_cc into β_‐3 and β_rich is consistent with the variation of replacement and richness differences. The partitioning of β_sor into β_sim and β_nes overestimates the replacement component and underestimates richness differences. The novel methodology allows the discrimination of different causes of beta‐diversity patterns along latitudinal, biogeographic or ecological gradients, by estimating correctly the relative contributions of replacement and richness differences.     

Influence of season on leaf litter ant (Hymenoptera: Formicidae) diversity in the locality of Minko'o (Southern,Cameroon)

Seasonality is known to influence ant activity in many tropical rain forests in the world such as South America and Africa. We surveyed ant fauna in the leaf litter in the locality of Minko'o. The work aimed to evaluate the effect of seasonal variation on the diversity and composition of litter ants. Ants were sampled from November 2015 to June 2017, using four sampling methods: visual capture, bait, pitfall trap and extraction. Species richness, Shannon diversity index and analysis of similarities were used to characterise diversity of ant communities between seasons. We collected 306 ant species, shared out between 56 genera and 11 subfamilies. Subfamilies Myrmicinae, Ponerinae, Dolichoderinae, Formicinae, Dorylinae, Cerapachyinae and Pseudomyrmecinae occurred in all the seasons. Species richness was highest in major dry season with 243 species followed by minor rainy season with 188, major rainy season with 177 species and finally minor dry season that recorded the lowest with 155 species. Kruskal–Wallis test showed that ant species richness did not differ between seasons (p > 0.05). Species diversity index indicated that diversity was the highest during minor dry season (H′ = 4.24), followed by the major dry season (H′ = 4.23), minor rainy season (H′ = 4.21) and lowest during major rainy season (H′ = 4.06). Eight most frequents ants have been recorded: Axinidris sp.1, Camponotus flavomarginatus, Monomorium guineense, Myrmicaria opaciventris, Odontomachus troglodytes, Carebara perpusilla, Paltothyreus tarsatus and Pheidole megacephala. Assessment of the seasonal effect on diversity reveals that dry season is richer and more diverse than rainy season and the season significantly influence the diversity of litter ants.     

Plant biodiversity in the Saint Catherine area of the Sinai peninsula, Egypt

This study focuses on plant species richness, taxonomic diversity, and endemism of the Sinai peninsula as a whole and Saint Catherine area in particular. Beta diversity was also measured using _T to represent the biotic change between different landforms in the St. Catherine area. The peninsula supports about 1285 species including the infraspecific taxa of which about 800 species (also including the infraspecific taxa) are recorded in the southern Sinai south of El-Tih Desert. The present study reveals that southern Sinai is more diverse as compared with the Sinai peninsula as a whole. Southern Sinai also supports more than the expected numbers of rare and very rare species (about 62%) and about 4.3% endemic species. Beta diversity between different landforms in the St. Catherine area reflect a large biotic change between slopes and terraces on the one hand and between terraces and ridges on the other. Finally, the study recommends appropriate management of the peninsula and more research for the management requirements of the numerous endemic and rare species in the Sinai peninsula.     

“How” and “what” matters: Sampling method affects biodiversity estimates of reef fishes

Understanding changes in biodiversity requires the implementation of monitoring programs encompassing different dimensions of biodiversity through varying sampling techniques. In this work, fish assemblages associated with the “outer” and “inner” sides of four marinas, two at the Canary Islands and two at southern Portugal, were investigated using three complementary sampling techniques: underwater visual censuses (UVCs), baited cameras (BCs), and fish traps (FTs). We firstly investigated the complementarity of these sampling methods to describe species composition. Then, we investigated differences in taxonomic (TD), phylogenetic (PD) and functional diversity (FD) between sides of the marinas according to each sampling method. Finally, we explored the applicability/reproducibility of each sampling technique to characterize fish assemblages according to these metrics of diversity. UVCs and BCs provided complementary information, in terms of the number and abundances of species, while FTs sampled a particular assemblage. Patterns of TD, PD, and FD between sides of the marinas varied depending on the sampling method. UVC was the most cost‐efficient technique, in terms of personnel hours, and it is recommended for local studies. However, for large‐scale studies, BCs are recommended, as it covers greater spatio‐temporal scales by a lower cost. Our study highlights the need to implement complementary sampling techniques to monitor ecological change, at various dimensions of biodiversity. The results presented here will be useful for optimizing future monitoring programs.