Tag: ecosystem services

DNA metabarcoding detects ecological stress within freshwater species

Metabarcoding allows scientists to extract DNA from the environment, in order to rapidly detect species inhabiting a particular habitat. While the method is a great tool that facilitates conservation activities, few studies have looked into its applicability in monitoring species’ populations and their genetic diversity, which could actually be critical to assess negative trends early on. The potential of the method is confirmed in a new study, published in the peer-reviewed scholarly journal Metabarcoding & Metagenomics.

In a new study, German scientists confirm that responses below species level can be inferred with DNA metabarcoding

Metabarcoding allows scientists to extract DNA from the environment (known as environmental DNA or eDNA), for example, river water or, as in the case of the study by the team from the University of Duisburg-Essen (Essen, Germany) within the German Barcode of Life project (GBOL II): Vera Zizka, Dr Martina Weiss and Prof Florian Leese, from individuals in bulk samples. Thus, they are able to detect what species inhabit a particular habitat.

However, while the method has already been known to be of great use in getting an approximate picture of local fauna, hence facilitating conservation prioritisation, few studies have looked into its applicability to infer responses below species level. That is, how the populations of a particular species fare in the environment of interest, also referred to as intraspecific diversity. Meanwhile, the latter could actually be a lot more efficient in ecosystem monitoring and, consequently, biodiversity loss mitigation.

The potential of the method is confirmed in a new study, published in the peer-reviewed scholarly journal Metabarcoding & Metagenomics. To do so, the researchers surveyed the populations of macroinvertebrate species (macrozoobenthos) in three German rivers: Emscher, Ennepe and Sieg, where each is subject to a different level of ecological disturbance. They were looking specifically at species reported at all of the survey sites by studying the number of different haplotypes (a set of DNA variations usually inherited together from the maternal parent) in each sample. The researchers point out that macrozoobenthos play a key role in freshwater ecosystem functionality and include a wide range of taxonomic groups with often narrow and specific demands with respect to habitat conditions.

“As the most basal level of biodiversity, genetic diversity within species is typically the first to decrease, and the last to regenerate, after stressor’s impact. It consequently provides a proxy for environmental impacts on communities long before, or even if never visible on species diversity level,”

explain the scientists.

Emscher is an urban stream in the Ruhr Metropolitan Area that has been used as an open sewage channel for the past hundred years, and is considered to be a very disturbed environment. Ennepe – regarded as moderately stressed – runs through both rural and urban sites, including ones with sewage treatment plant inflow. Meanwhile, Sieg is considered as a stable, near-natural river system with a good ecological and chemical status.

As a result, despite their original assumption that Sieg would support the most prominent diversity within populations of species sensitive to organic pollution, such as mayflies, stoneflies and caddisflies, the scientists reported no significant difference to the medium stressed river Ennepe. This was also true for overall biodiversity. On the other hand, the team discovered higher intraspecific diversity for species resilient to ecological disturbance like small worms and specialised crustaceans in the heavily disturbed Emscher. The latter phenomenon may be explained with low competition pressure for these species, their ability to use organic compounds as resources and, consequently, increased population growth.

“[T]his pioneer study shows that the extraction of intraspecific genetic variation, so-called ‘haplotypes’ from DNA metabarcoding datasets is a promising source of information to assess intraspecific diversity changes in response to environmental impacts for a whole metacommunity simultaneously,”

conclude the scientists.

However, the researchers also note limitations of their study, including the exclusion of specialist species that only occured at single sites. They prompt future studies to also carefully control for the individual number of specimens per species to quantify genetic diversity change specifically.

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Original source:

Zizka VMA, Weiss M, Leese F (2020) Can metabarcoding resolve intraspecific genetic diversity changes to environmental stressors? A test case using river macrozoobenthos. Metabarcoding and Metagenomics 4: e51925. https://doi.org/10.3897/mbmg.4.51925

Scientists unravel the evolution and relationships for all European butterflies in a first

For the first time, a complete time-calibrated phylogeny for a large group of invertebrates is published for an entire continent. A German-Swedish team of scientists provide a diagrammatic hypothesis of the relationships and evolutionary history for all 496 European species of butterflies currently in existence. Their study provides an important tool for evolutionary and ecological research, meant for the use of insect and ecosystem conservation.

For the first time, a complete time-calibrated phylogeny for a large group of invertebrates is published for an entire continent. 

The figure shows the relationships of the 496 extant European butterfly species in the course of their evolution during the last 100 million years.
Image by Dr Martin Wiemers

In a recent research paper in the open-access, peer-reviewed academic journal ZooKeys, a German-Swedish team of scientists provide a diagrammatic hypothesis of the relationships and evolutionary history for all 496 European species of butterflies currently in existence. Their study provides an important tool for evolutionary and ecological research, meant for the use of insect and ecosystem conservation.

In order to analyse the ancestral relationships and history of evolutionary divergence of all European butterflies currently inhabiting the Old continent, the team led by Martin Wiemers – affiliated with both the Senckenberg German Entomological Institute and the Helmholtz Centre for Environmental Research – UFZ, mainly used molecular data from already published sources available from NCBI GenBank, but also contributed many new sequences, some from very local endemics for which no molecular data had previously been available.

The phylogenetic tree also includes butterfly species that have only recently been discovered using molecular methods. An example is this Blue (Polyommatus celina), which looks similar to the Common Blue. It used to be mistaken for the Common Blue in the Canary Islands and the southwestern part of the Mediterranean Region.
Photo by Dr Martin Wiemers

Butterflies, the spectacular members of the superfamily Papilionoidea, are seen as an important proponent for nature conservation, as they present an excellent indicator group of species, meaning they are capable of inferring the environmental conditions of a particular habitat. All in all, if the local populations of butterflies are thriving, so is their habitat.

Furthermore, butterflies are pollinating insects, which are of particular importance for the survival of humans. There is no doubt they have every right to be recognised as a flagship invertebrate group for conservation.

While many European butterflies are seriously threatened, this one: Madeiran Large White (Pieris wollastoni) is already extinct. The study includes the first sequence of this Madeiran endemic which was recorded in 1986 for the last time. The tree demonstrates that it was closely related to the Canary Island Large White (Pieris cheiranthi), another threatened endemic butterfly, which survives only on Tenerife and La Palma, but is already extinct on La Gomera.
Photo by Dr Martin Wiemers

In recent times, there has been a steady increase in the molecular data available for research, however, those would have been only used for studies restricted either to a selected subset of species, or to small geographic areas. Even though a complete phylogeny of European butterflies was published in 2019, also co-authored by Wiemers, it was not based on a global backbone phylogeny and, therefore, was also not time-calibrated.

In their paper, Wiemers and his team point out that phylogenies are increasingly used across diverse areas of macroecological research, such as studies on large-scale diversity patterns, disentangling historical and contemporary processes, latitudinal diversity gradients or improving species-area relationships. Therefore, this new phylogeny is supposed to help advance further similar ecological research.

The study includes molecular data from 18 localised endemics with no public DNA sequences previously available, such as the Canary Grayling (Hipparchia wyssii), which is only found on the island of Tenerife (Spain).
Photo by Dr Martin Wiemers

Original source: 

Wiemers M, Chazot N, Wheat CW, Schweiger O, Wahlberg N (2020) A complete time-calibrated multi-gene phylogeny of the European butterflies. ZooKeys 938: 97-124. https://doi.org/10.3897/zookeys.938.50878

Ten years of ecosystem services matrix: Review of a (r)evolution

In recent years, the concept of Ecosystem Services (ES): the benefits people obtain from ecosystems, such as pollination provided by bees for crop growing, timber provided by forests or recreation enabled by appealing landscapes, has been greatly popularised, especially in the context of impeding ecological crises and constantly degrading natural environments. 

Hence, there has been an increasing need for robust and practical methodologies to assess ES, in order to provide key stakeholders and decision-makers with crucial information. One such method to map and assess ES: the ES Matrix approach, has been increasingly used in the last decade.

The ES Matrix approach is based on the use of a lookup table consisting of geospatial units (e.g. types of ecosystems, habitats, land uses) and sets of ES, meant to be assessed for a specific study area, which means that the selection of a particular study area is the starting point in the assessment. Only then, suitable indicators and methods for ES quantification can be defined. Based on this information, a score for each of the ES considered is generated, referring to ES potential, ES supply, ES flow/use or demand for ES. 

Originally developed in a 2009 paper by a team, led by Prof Dr Benjamin Burkhard (Leibniz University Hannover and Leibniz Centre for Agricultural Landscape Research ZALF), the ES Matrix allows the assessment of the capacity of particular ecosystem types or geospatial units to provide ES.

Ten years later, a research led by Dr C. Sylvie Campagne (Leibniz University Hannover, Germany), Dr Philip Roche (INRAE, France), Prof Dr Felix Muller (University of Kiel, Germany) and Prof Dr Benjamin Burkhard conducted a review of 109 published studies applying the ES matrix approach to find out how the ES matrix approach was applied and whether this was done in an oversimplified way or not.

In their recent paper, published in the open-access, peer-reviewed journal One Ecosystem, the review confirms the method’s flexibility, appropriateness and utility for decision-making, as well as its ability to increase awareness of ES. Nevertheless, the ES matrix approach has often been used in a “quick and dirty” way that urges more transparency and integration of variability analyses, they conclude.

“We analysed the diversity of application contexts, highlighted trends of uses and proposed future recommendations for improved applications of the ES matrix. Amongst the main patterns observed, the ES matrix approach allows for the assessment of a higher number of ES than other ES assessment methods. ES can be jointly assessed with indicators for ecosystem condition and biodiversity in the ES matrix,”

explains Campagne.

“Although the ES matrix allows us to consider many data sources to achieve the assessment scores for the individual ES, these were mainly used together with expert-based scoring (73%) and/or ES scores that were based on an already-published ES matrix or deduced by information found in related scientific publications (51%),”

she elaborates. 

In 29% of the studies, an already existing matrix was used as an initial matrix for the assessment and in 16% no other data were used for the matrix scores or no adaptation of the existing matrix used was made. 

“Nevertheless, we recommend to use only scores assessed for a specific study or, if one wishes to use pre-existing scores from another study, to revise them in depth, taking into account the local context of the new assessment,”

she points out.

The researchers also acknowledge the fact that 27% of the reviewed studies did not clearly explain their methodology, which underlines the lack of method elucidation on how the data had been used and where the scores came from. Although some studies addressed the need to consider variabilities and uncertainties in ES assessments, only a minority of studies (15%) did so. Thus, the team also recommends to systematically report and consider variabilities and uncertainties in each ES assessment.

“We emphasise the need for all scientific studies to describe clearly and extensively the whole methodology used to score or evaluate ES, in order to be able to rate the quality of the scores obtained. The increasing number of studies that use the ES matrix approach confirms its success, appropriateness, flexibility and utility to generate information for decision-making, as well as its ability to increase awareness of ES, but the application of the ES matrix has to become more transparent and integrate more variability analyses,”

concludes the research team.

Original source:
Campagne CS, Roche P, Müller F, Burkhard B (2020) Ten years of ecosystem services matrix: Review of a (r)evolution. One Ecosystem 5: e51103. https://doi.org/10.3897/oneeco.5.e51103

‘Insectageddon’ is ‘alarmist by bad design’: Scientists point out the study’s major flaws

Many insects species require pristine environments, including old-growth forests. Photo by Atte Komonen.

Earlier this year, a research article triggered a media frenzy by predicting that as a result of an ongoing rapid decline, nearly half of the world’s insects will be no more pretty soon

Amidst worldwide publicity and talks about ‘Insectageddon’: the extinction of 40% of the world’s insects, as estimated in a recent scientific review, a critical response was published in the open-access journal Rethinking Ecology.

Query- and geographically-biased summaries; mismatch between objectives and cited literature; and misuse of existing conservation data have all been identified in the alarming study, according to Drs Atte Komonen, Panu Halme and Janne Kotiaho of the University of Jyväskylä (Finland). Despite the claims of the review paper’s authors that their work serves as a wake-up call for the wider community, the Finnish team explain that it could rather compromise the credibility of conservation science.

The first problem about the paper, titled “Worldwide decline of the entomofauna: A review of its drivers” and published in the journal Biological Conservation, is that its authors have queried the Web of Science database specifically using the keywords “insect”, “decline” and “survey”.

“If you search for declines, you will find declines. We are not questioning the conclusion that insects are declining,” Komonen and his team point out, “but we do question the rate and extent of declines.”

Many butterflies have declined globally. Scolitantides orion, for example, is an endangered species in Finland. Photo by Atte Komonen.

The Finnish research team also note that there are mismatches between methods and literature, and misuse of IUCN Red List categories. The review is criticised for grouping together species, whose conservation status according to the International Union for Conservation of Nature (IUCN) is Data Deficient with those deemed Vulnerable. By definition, there are no data for Data Deficient species to assess their declines.

In addition, the review paper is seen to use “unusually forceful terms for a peer-reviewed scientific paper,” as the Finnish researchers quote a recent news story published in The Guardian. Having given the words dramatic, compelling, extensive, shocking, drastic, dreadful, devastating as examples, they add that that such strong intensifiers “should not be acceptable” in research articles.

“As actively popularising conservation scientists, we are concerned that such development is eroding the importance of the biodiversity crisis, making the work of conservationists harder, and undermining the credibility of conservation science,” the researchers explain the motivation behind their response.

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Original source:

Komonen A, Halme P, Kotiaho JS (2019) Alarmist by bad design: Strongly popularized unsubstantiated claims undermine credibility of conservation science. Rethinking Ecology 4: 17-19. https://doi.org/10.3897/rethinkingecology.4.34440