Geert De Knijf

European Red List of dragonflies

The European Red List is a review of the conservation status of c.6,000 European species (mammals, reptiles, amphibians, freshwater fishes, butterflies, dragonflies, and selected groups of beetles, ...

Species richness coincidence: conservation strategies based on predictive modelling

The present-day geographic distribution of individual species of five taxonomic groups (plants, dragonflies, butterflies, herpetofauna and breeding birds) is relatively well-known on a small scale (5 × 5 km squares) in Flanders (north Belgium). These data allow identification of areas with a high diversity within each of the species groups. However, differences in mapping intensity and coverage hamper straightforward comparisons of species-rich areas among the taxonomic groups. To overcome this problem, we modelled the species richness of each taxonomic group separately using various environmental characteristics as predictor variables (area of different land use types, biotope diversity, topographic and climatic features). We applied forward stepwise multiple regression to build the models, using a subset of well-surveyed squares. A separate set of equally well-surveyed squares was used to test the predictions of the models. The coincidence of geographic areas with high predicted species richness was remarkably high among the four faunal groups, but much lower between plants and each of the four faunal groups. Thus, the four investigated faunal groups can be used as relatively good indicator taxa for one another in Flanders, at least for their within-group species diversity. A mean predicted species diversity per mapping square was also estimated by averaging the standardised predicted species richness over the five taxonomic groups, to locate the regions that were predicted as being the most species-rich for all five investigated taxonomic groups together. Finally, the applicability of predictive modelling in nature conservation policy both in Flanders and in other regions is discussed.

Predicted insect diversity declines under climate change in an already impoverished region

Being ectotherms, insects are predicted to suffer more severely from climate change than warm-blooded animals. We forecast possible changes in diversity and composition of butterflies, grasshoppers and dragonflies in Belgium under increasingly severe climate change scenarios for the year 2100. Two species distribution modelling techniques (Generalised Linear Models and Generalised Additive Models), were combined via a conservative version of the ensemble forecasting strategy to predict present-day and future species distributions, considering the species as potentially present only if both modelling techniques made such a prediction. All models applied were fair to good, according to the AUC (area under the curve of the receiver operating characteristic plot), sensitivity and specificity model performance measures based on model evaluation data. Butterfly and grasshopper diversity were predicted to decrease significantly in all scenarios and species-rich locations were predicted to move towards higher altitudes. Dragonfly diversity was predicted to decrease significantly in all scenarios, but dragonfly-rich locations were predicted to move upwards only in the less severe scenarios. The largest turnover rates were predicted to occur at higher altitudes for butterflies and grasshoppers, but at intermediate altitudes for dragonflies. Our results highlight the challenge of building conservation strategies under climate change, because the changes in the sites important for different groups will not overlap, increasing the area needed for protection. We advocate that possible conservation and policy measures to mitigate the potentially strong impacts of climate change on insect diversity in Belgium should be much more pro-active and flexible than is the case presently.

The status of two boreo-alpine species, Somatochlora alpestris and S. arctica, in Romania and their vulnerability to the impact of climate change (Odonata: Corduliidae)

It is expected that climate change will have a great impact on many species and habitats. This will be greater if populations are found at the edge of their range or are isolated, and could lead to regional extinction. Here we investigate the possible impact on two boreo-alpine dragonfly species, Somatochlora alpestris and S. arctica, at their range margins. Both species were unknown for most parts of south-eastern Europe. In 2007 we found 15 localities for S. alpestris and two for S. arctica in the Carpathian Mountains of Romania. Both species are there confined to mountain peat bogs. All localities are situated between 1300 m and 2100 m altitude, with the majority restricted to a small range between 1600 m and 1800 m. Based on the factor altitude we predict a hypothetical distribution map for S. alpestris. The underlying models exclusively rely on the ultimate factor “altitude” and explain more than 60% of the deviance. In addition, we assessed the impact of climate change for two scenarios: a 1.5°C temperature increase and a 3°C increase. The first resulted in altitudinal range shifts of +200 m and in a distributional shrinkage of 40%, the latter corresponds to an upward range shift of 600 m and a loss of 90% of the area. Habitat specialists, especially those at their margins of distribution, are hardly able to keep pace with climate change. It seems unlikely that mountain peat bogs will develop at rates comparable to those of current climate change. This may effect regional extinctions of boreo-alpine species.

Distribution, ecology and status of a threatened species Ischnura intermedia (Insecta: Odonata), new for Europe

The dragonfly genus Ischnura has been the subject of numerous studies and is well studied in Europe and the Middle East. Nevertheless, information on the ecology, habitat preferences and phylogenetic relationships of some species is deficient. One species lacking such data is Ischnura intermedia, a near endemic species of the Middle East, found for the first time in Europe on Cyprus in 2013, where it occurs in five river valleys. In this study, we monitored I. intermedia in Cyprus where the species has a long flight period from the end of March until mid-November. Our results show that it has two and possibly even three generations a year, with the males of the first generation having reduced blue coloration on abdominal segments 8 and 9. Ischnura intermedia is confined to small secondary channels adjacent to streams and rivulets where the current slows and water is retained. It appears that populations can only become established at sites that have permanent water. It is therefore anticipated that the species will be under severe pressure within its range. We suggest listing this species as “Endangered” in Europe and globally as “Vulnerable” following the IUCN Red List Categories and Criteria and to prepare a species action plan for the European population of Ischnura intermedia on Cyprus. Two partial DNA fragments, mtDNA cytochrome b (Cytb) and cytochrome oxidase subunit I (COI) were used to gain insights into the phylogenetic position within Ischnura, especially within the I. pumilio clade. We demonstrate that I. intermedia is clearly separated from I. pumilio, but closely related to I. forcipata.

Genetic signature of the colonisation dynamics along a coastal expansion front in the damselfly Coenagrion scitulum

1. Many insects are expanding their distribution range polewards as a result of climate change, which has been shown to be associated with founder effects leading to a reduction in genetic diversity and an increase in genetic differentiation. These spatial genetic patterns may arise from colonisation from a broad expansion front or a limited neighbourhood after a stepping stone model of dispersal. The temporal persistence of such founder effects are poorly understood, mainly because studies looking at the fine‐scale initial temporal dynamics of the genetic signature of a range expansion are rare.

Diversity and conservation of European dragonflies and damselflies (Odonata)

Based on a distribution database brought together for the recently published Atlas of the European dragonflies and damselflies, we describe the patterns of diversity and endemism of these insect groups. Highest species richness, as well as richness of predominantly lentic species, occurs in central and western-central Europe. Strictly lotic species have their centre of diversity in southwest France and parts of the Iberian Peninsula. The highest number of endemic species is found in southwest France, the Iberian Peninsula and the Balkan Peninsula. A comparison of the diversity patterns of Odonata species listed in the EU Habitats Directive with those listed in the European Red List highlights a strong mismatch between species threatened in Europe, which are mainly found in the Mediterranean, and species legally protected by the European Union, which are concentrated in central and western Europe. This mismatch has a historical origin, as the species listed in the Habitats Directive were mostly selected in the 1970s and 1980s when water quality in western and central Europe was poor. Since the 1990s, water and habitat quality has improved in these parts of Europe while in the same period the pressure on aquatic habitats in the Mediterranean has increased greatly.

Genetic signature of the colonisation dynamics along a coastal expansion front in the damselflyCoenagrion scitulum: Colonisation dynamics along an expansion front

1. Many insects are expanding their distribution range polewards as a result of climate change, which has been shown to be associated with founder effects leading to a reduction in genetic diversity and an increase in genetic differentiation. These spatial genetic patterns may arise from colonisation from a broad expansion front or a limited neighbourhood after a stepping stone model of dispersal. The temporal persistence of such founder effects are poorly understood, mainly because studies looking at the fine‐scale initial temporal dynamics of the genetic signature of a range expansion are rare.

Genetic signature of the colonization dynamics along a coastal expansion front in the damselfly Coenagrion scitulum (Zygoptera: Coenagrionidae)

1. Many insects are expanding their distribution range polewards as a result of climate change, which has been shown to be associated with founder effects leading to a reduction in genetic diversity and an increase in genetic differentiation. These spatial genetic patterns may arise from colonisation from a broad expansion front or a limited neighbourhood after a stepping stone model of dispersal. The temporal persistence of such founder effects are poorly understood, mainly because studies looking at the fine‐scale initial temporal dynamics of the genetic signature of a range expansion are rare.