Enhancing the structural diversity between forest patches—A concept and real-world experiment to study biodiversity,multifunctionality and forest resilience across spatial scales

Intensification of land use by humans has led to a homogenization of landscapes and decreasing resilience of ecosystems globally due to a loss of biodiversity, including the majority of forests. Biodiversity–ecosystem functioning (BEF) research has provided compelling evidence for a positive effect of biodiversity on ecosystem functions and services at the local (α-diversity) scale, but we largely lack empirical evidence on how the loss of between-patch β-diversity affects biodiversity and multifunctionality at the landscape scale (γ-diversity). Here, we present a novel concept and experimental framework for elucidating BEF patterns at α-, β-, and γ-scales in real landscapes at a forest management-relevant scale. We examine this framework using 22 temperate broadleaf production forests, dominated by Fagus sylvatica. In 11 of these forests, we manipulated the structure between forest patches by increasing variation in canopy cover and deadwood. We hypothesized that an increase in landscape heterogeneity would enhance the β-diversity of different trophic levels, as well as the β-functionality of various ecosystem functions. We will develop a new statistical framework for BEF studies extending across scales and incorporating biodiversity measures from taxonomic to functional to phylogenetic diversity using Hill numbers. We will further expand the Hill number concept to multifunctionality allowing the decomposition of γ-multifunctionality into α- and β-components. Combining this analytic framework with our experimental data will allow us to test how an increase in between patch heterogeneity affects biodiversity and multifunctionality across spatial scales and trophic levels to help inform and improve forest resilience under climate change. Such an integrative concept for biodiversity and functionality, including spatial scales and multiple aspects of diversity and multifunctionality as well as physical and environmental structure in forests, will go far beyond the current widely applied approach in forestry to increase resilience of future forests through the manipulation of tree species composition.     

The significance of partial migration for food web and ecosystem dynamics

Migration is ubiquitous and can strongly shape food webs and ecosystems. Less familiar, however, is that the majority of life cycle, seasonal and diel migrations in nature are partial migrations: only a fraction of the population migrates while the other individuals remain in their resident ecosystem. Here, we demonstrate different impacts of partial migration rendering it fundamental to our understanding of the significance of migration for food web and ecosystem dynamics. First, partial migration affects the spatiotemporal distribution of individuals and the food web and ecosystem-level processes they drive differently than expected under full migration. Second, whether an individual migrates or not is regularly correlated with morphological, physiological, and/or behavioural traits that shape its food-web and ecosystem-level impacts. Third, food web and ecosystem dynamics can drive the fraction of the population migrating, enabling the potential for feedbacks between the causes and consequences of migration within and across ecosystems. These impacts, individually and in combination, can yield unintuitive effects of migration and drive the dynamics, diversity and functions of ecosystems. By presenting the first full integration of partial migration and trophic (meta-)community and (meta-)ecosystem ecology, we provide a roadmap for studying how migration affects and is affected by ecosystem dynamics in a changing world.     

Hydrodynamics in early animal evolution

Choanoflagellates and sponges feed by filtering microscopic particles from water currents created by the flagella of microvillar collar complexes situated on the cell bodies of the solitary or colonial choanoflagellates and on the choanocytes in sponges. The filtering mechanism has been known for more than a century, but only recently has the filtering process been studied in detail and also modelled, so that a detailed picture of the water currents has been obtained. In the solitary and most of the colonial choanoflagellates, the water flows freely around the cells, but in some forms, the cells are arranged in an open meshwork through which the water can be pumped. In the sponges, the choanocytes are located in choanocyte chambers (or choanocyte areas) with separate incurrent and excurrent canals/pores located in a larger body, which enables a fixed pattern of water currents through the collar complexes. Previous theories for the origin of sponges show evolutionary stages with choanocyte chambers without any opening or with only one opening, which makes separation of incurrent and excurrent impossible, and such stages must have been unable to feed. Therefore a new theory is proposed, which shows a continuous evolutionary lineage in which all stages are able to feed by means of the collar complexes.     

The distribution of coastal fish eDNA sequences in the Anthropocene

Aim

Coastal fishes have a fundamental role in marine ecosystem functioning and contributions to people, but face increasing threats due to climate change, habitat degradation and overexploitation. The extent to which human pressures are impacting coastal fish biodiversity in comparison with geographic and environmental factors at large spatial scale is still under scrutiny. Here, we took advantage of environmental DNA (eDNA) metabarcoding to investigate the relationship between fish biodiversity, including taxonomic and genetic components, and environmental but also socio-economic factors.

Location

Tropical, temperate and polar coastal areas.

Time period

Present day.

Major taxa studied

Marine fishes.

Methods

We analysed fish eDNA in 263 stations (samples) in 68 sites distributed across polar, temperate and tropical regions. We modelled the effect of environmental, geographic and socio-economic factors on α- and β-diversity. We then computed the partial effect of each factor on several fish biodiversity components using taxonomic molecular units (MOTU) and genetic sequences. We also investigated the relationship between fish genetic α- and β-diversity measured from our barcodes, and phylogenetic but also functional diversity.

Results

We show that fish eDNA MOTU and sequence α- and β-diversity have the strongest correlation with environmental factors on coastal ecosystems worldwide. However, our models also reveal a negative correlation between biodiversity and human dependence on marine ecosystems. In areas with high dependence, diversity of all fish, cryptobenthic fish and large fish MOTUs declined steeply. Finally, we show that a sequence diversity index, accounting for genetic distance between pairs of MOTUs, within and between communities, is a reliable proxy of phylogenetic and functional diversity.

Main conclusions

Together, our results demonstrate that short eDNA sequences can be used to assess climate and direct human impacts on marine biodiversity at large scale in the Anthropocene and can further be extended to investigate biodiversity in its phylogenetic and functional dimensions.     

Einflüsse von Licht und temperatur auf den Winterschlaf des Siebenschläfers Glis g. glis (Linnaeus 1766)

Zusammenfassung Vom Sommer 1956 bis zum Frühjahr 1959 wurden mit Siebenschläfern (Glis glis L.) Licht- und Temperaturversuche durchgeführt. Jede Versuchsgruppe war in einem besonderen Versuchsraum untergebracht. Daneben wurden Beobachtungen an wildlebenden Bilchen durchgeführt.Eine Gruppe von Siebenschläfern lebte in einer Voliere im Freien, eine zweite in einem Tierstall mit natürlichen Lichtverhältnissen ohne UV, 2 Tiere waren in einem ähnlichen Raum untergebracht und wurden täglich 1 Std UV-bestrahlt. Diese beiden Tierräume wurden im Winter geheizt (meist über 20° C). Eine Gruppe lebte in einem Klimaraum (wechselnde Temperaturen), in dem täglich 18 Std lang Kunstlicht brannte. Einer letzten Gruppe wurde im Frühsommer die Tagdauer rasch verkürzt, so daß im Hochsommer schon Kurztag herrschte (Raumtemperatur über 20° C).Es wurden untersucht: das Körpergewicht, das Haarkleid, die motorische Aktivität und die Körpertemperatur.Auf Grund der Versuche wurde folgendes festgestellt: Das Körpergewicht bildet bei Tieren, die unter natürlichen Lichtverhältnissen leben, einen ausgeprägten Jahreszyklus. Bei Bilchen im ständigen Langtag war dieser nicht mehr zu erkennen; die Gewichte blieben gleich. Es fand demnach keine Fettspeicherung im Herbst statt. Obwohl das Haarkleid oft gewechselt wurde, blieb stets ein Sommerpelz erhalten. Ebenso war die motorische Aktivität dieser Bilche stets die gleiche, während Normaltiere ein Absinken der Aktivität im Herbst und ein Wiederansteigen im Frühjahr zeigten. Durch frühzeitige Verkürzung der Tagdauer konnten die Tiere schon im Juli veranlaßt werden, Fett zu speichern und ihr Haarkleid zu wechseln.Die Außentemperatur hat nicht den Einfluß auf den Winterschlaf, den man ihr meist zuschrieb. Im Winter schliefen Normaltiere bei Temperaturen um 24° C noch verhältnismäßig tief. Die Schlaftiefe ist allerdings bei niederen Temperaturen größer als bei hohen. Demnach stellt die Temperatur einen wichtigen, sekundären Faktor dar. Normale Sommertiere und Bilche aus dem ständigen Langtag blieben auch bei Kälte wach, wenn genügend Nahrung vorhanden war.Es wird der Schluß gezogen, daß durch die jahreszeitlichen Veränderungen der Tag-Nachtdauer eine endokrine Umstellung stattfindet, die Reservenspeicherung sowie die Winterschlafbereitschaft auslöst. Die Temperatur greift dann erst sekundär ein, indem sie die Tiefe der Lethargie steuert. Trotzdem erfolgt in gewissen Zeitabständen ein spontanes Erwachen.Das Problem Winterschlaf — Torpidity wird an Hand eigener Ergebnisse sowie Untersuchungen anderer Autoren diskutiert und dabei festgestellt, daß ersterer ein komplexes Phänomen darstellt, das vom Organismus wohl vorbereitet wird, während die Torpidity einer Kältestarre vergleichbar ist. Letztere ist daher nicht mit Winterschlaf gleichzusetzen.     

Cloning of the amphibolic Calvin cycle/OPPP enzyme d-ribulose-5-phosphate 3-epimerase (EC 5.1.3.1) from spinach chloroplasts: functional and evolutionary aspects

Exploiting the differential expression of genes for Calvin cycle enzymes in bundle-sheath and mesophyll cells of the C4 plant Sorghum bicolor L., we isolated via subtractive hybridization a molecular probe for the Calvin cycle enzyme d-ribulose-5-phosphate 3-epimerase (R5P3E) (EC 5.1.3.1), with the help of which several full-size cDNAs were isolated from spinach. Functional identity of the encoded mature subunit was shown by R5P3E activity found in affinity-purified glutatione S-transferase fusions expressed in Escherichia coli and by three-fold increase of R5P3E activity upon induction of E. coli overexpressing the spinach subunit under the control of the bacteriophage T₇ promoter, demonstrating that we have cloned the first functional ribulose-5-phosphate 3-epimerase from any eukaryotic source. The chloroplast enzyme from spinach shares about 50% amino acid identity with its homologues from the Calvin cycle operons of the autotrophic purple bacteria Alcaligenes eutrophus and Rhodospirillum rubrum. A R5P3E-related eubacterial gene family was identified which arose through ancient duplications in prokaryotic chromosomes, three R5P3E-related genes of yet unknown function have persisted to the present within the E. coli genome. A gene phylogeny reveals that spinach R5P3E is more similar to eubacterial homologues than to the yeast sequence, suggesting a eubacterial origin for this plant nuclear gene.Abbreviations R5P3E d-ribulose-5-phosphate 3-epimerase - RPI ribose-5-phosphate isomerase - TKL transketolase - PRK phosphoribulokinase - GAPDH glyceraldehyde-3-phosphate dehydrogenase - FBP fructose-1,6-bisphophatase - FBP fructose 1,6-bisphosphate - G6PDH glucose-6-phosphate dehydrogenase - 6PGDH 6-phosphogluconate dehydrogenase - OPPP oxidative pentose phosphate pathway - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - FBA fructose-1,6-bisphophate aldolase - IPTG isopropyl -d-thiogalactoside - GST glutathione S-tranferase - PBS phosphate-buffered saline - TPI triosephosphate isomerase     

Identification of a cDNA/Protein Leading to an Increased P i -uptake in Xenopus laevis Oocytes

In a previous report we documented an increased Na⁺-dependent transport of inorganic phosphate (P _i ) in Xenopus laevis oocytes injected with mRNA isolated from rabbit duodenum (Yagci et al., Pfluegers Arch. 422:211–216, 1992; ref 24). In the present study we have used expression cloning in oocytes to search for the cDNA/mRNA involved in this effect. The identified cDNA (provisionally named PiUS; for P _i -uptake stimulator) lead to a 3-4-fold stimulation of Na⁺-dependent P _i -uptake (10ng cRNA injected, 3–5 days of expression). Na⁺-independent uptake of P _i was also affected but transport of sulphate and l-arginine (in the presence or absence of sodium) remained unchanged. The apparent K _m -values for the induced Na⁺-dependent uptake were 0.26 ± 0.04 mm for P _i and 14.8 ± 3.0 mm for Na⁺. The 1796 bp cDNA codes for a protein of 425 amino acids. Hydropathy analysis suggests a lack of transmembrane segments. In vitro translation resulted in a protein of 60 kDa and provided no evidence of glycosylation. In Northern blots a mRNA of ∼2 kb was recognized in various tissues including different intestinal segments, kidney cortex, kidney medulla, liver and heart. Homology searches showed no similarity to proteins involved in membrane transport and its control. In conclusion, we have cloned from a rabbit small intestinal cDNA library a novel cDNA encoding a protein stimulating P _i -uptake into Xenopus laevis oocytes, but which is not a P _i -transporter itself. Received: 31 July 1996/Revised: 16 October 1996