Effects of genetic diversity of grass on insect species diversity at higher trophic levels are not due to cascading diversity effects

AbstractCropping systems that rely on renewable energy and resources and are based on ecological principles could be more stable and productive into the future than current monoculture systems with serious unintended environmental consequences such as soil erosion and water pollution. In nonagricultural systems, communities with higher species diversity have higher productivity and provide other ecosystem services. However, communities of well-adapted crop species selected for biomass production may respond differently to increasing diversity. Diversity effects may be due to complementarity among species (complementary resource use and facilitative interactions) or positive selection effects (e.g., species with higher productivity dominate the mixture), and these effects may change over time or across environments. Our goal was to identify the ecological mechanisms causing diversity effects in a biodiversity experiment using agriculturally relevant species, and evaluate the implications for the design of sustainable cropping systems. We seeded seven perennial forage species in a replicated field experiment at two locations in Iowa, USA, and evaluated biomass productivity of monocultures and two- to six-species mixtures over 3 years after the establishment year under management systems of contrasting intensity: one or three harvests per year. Productivity increased with seeded species richness in all environments, and the positive relationship did not change over time. Polyculture overyielding was due to complementarity among species in the community rather than to selection effects of individual species. Complementarity increased as a log-linear function of species richness in all environments, and this trend was consistent across years. Legume–grass facilitation may explain much of this complementarity effect. Although individual species with high biomass production had a major effect on productivity of mixtures, the species producing the highest biomass in monoculture changed over the years in most environments. Furthermore, transgressive overyielding was observed and was more prevalent in later years, in some environments. We conclude that choosing a single well-adapted species for maximizing productivity may not be the best alternative over the long term and that high levels of species diversity should be included in the design of productive and ecologically sound agricultural systems.

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Microhabitats Utilization by Solitary Parasitoids and Predatory Insects as Indicators of Oil Palm Agroecosystem’s Capacity to Support Insect Species Diversity

Sains Malaysiana ◽

10.17576/jsm-2021-5008-02 ◽

2021 ◽

Vol 50 (8) ◽

pp. 2153-2166

Author(s):

Ahmad Bukhary A.K. ◽

Ruslan M.Y. ◽

Noor Hisham H. ◽

Muzamil M. ◽

Abu Hassan A. ◽

...

Keyword(s):

Species Diversity ◽

Cover Crops ◽

Oil Palm ◽

Vegetation Type ◽

Chemical Fertilizer ◽

Insect Species ◽

Herbicide Application ◽

Abundance Patterns ◽

Predatory Insects ◽

Abundance Fluctuations

Microhabitats capacity to support insect species diversity and persistence were evaluated implementing solitary parasitoids and predatory insects according to different phases of herbicide and chemical fertilizer applications. Two species of the genus Xanthopimpla (Ichneumonidae) and one species of the genus Pompilus (Pompilidae) showed relationships on vegetation-type microhabitats, notably natural weeds, leguminous cover crops, and the beneficial plant Turnera subulata, while two species of the genus Evania (Evaniidae) showed relationships with chipped oil palm trunks. One species from the genus Odontomachus (Formicidae) as an exclusive predatory ant was related to both chipped oil palm trunks and the beneficial plant T. subulata. Xanthopimpla parasitoids exhibited abundance fluctuations difference around natural weeds during herbicide application phases between three- and six-years old oil palm stands, with decreased and increased abundance patterns of the former and the latter, respectively. 18 years old oil palm stand showed increased abundance patterns only along with the different phases of chemical fertilizer applications. The importance of natural weeds diversity, restrictions of leguminous cover crops, frequency of herbicide applications, and the arrangements between beneficial plants and wood-based microhabitats that benefited insect parasitoids and predators were discussed.

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Can plant-soil feedback link genetic diversity and species diversity?

10.22541/au.160103349.98871662 ◽

2020 ◽

Author(s):

Lana Bolin ◽

Jennifer Lau

Keyword(s):

Genetic Diversity ◽

Species Diversity ◽

Plant Soil ◽

Soil Feedback

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Spatial Distribution of Insect Diversity in Selected Locations within Forestry Research Institute of Nigeria, Ibadan, Nigeria

Journal of Applied Sciences and Environmental Management ◽

10.4314/jasem.v25i7.21 ◽

2021 ◽

Vol 25 (7) ◽

pp. 1249-1255

Author(s):

O.A. Aina-Oduntan ◽

Q.A. Onilude ◽

J.A. George-Onaho ◽

A.I. Woghiren ◽

O.R. Jeminiwa

Keyword(s):

Species Diversity ◽

Relative Abundance ◽

Habitat Modification ◽

Insect Species ◽

Line Transect ◽

Microsoft Excel ◽

Forestry Research ◽

Significant Difference ◽

Ibadan Nigeria ◽

Research Institute

With the increase in the rate of tree removal and construction of buildings within the Forestry Research Institute of Nigeria premises, there has been concomitant rise in habitat modification. These changes in habitat composition affect the insect population. This study therefore investigated the insect species diversity and abundance within some selected locations within FRIN with the view to determining different insect species available in FRIN premises. Sweep nets were used to trap the insects along a predetermined line transect. Data were analyzed using Microsoft Excel 2007 and Paleontological Statistics were used for the data analysis. Descriptive statistics, one-way analysis of variance (ANOVA) and species diversity and composition were all assessed. A total number of 1073 individual insects belonging to 6 orders, 27 families and 34 species were recorded across the three locations. Out of this, Order Lepidoptera had the highest relative abundance (53%), followed by Coleoptera (22%), then by Hymenoptera, Hemiptera, Heteroptera and Diptera with 10%, 9%, 4% and 2% relative abundance respectively. The result of ANOVA showed that there was no significant difference in species composition/richness across the locations at probability level of 5%. The insect species diversity, evenness and richness also varied across the locations. This study therefore, brings to the fore the diversity and abundance of insects within FRIN premises and highlighted the need for a more intensive study by the entomology section and for sustainable actions to be taken in conserving beneficial rare species while, managing the abundant pestiferous ones.

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Genetic diversity increases food-web persistence in the face of climate warming

10.1101/2020.06.23.167387 ◽

2020 ◽

Author(s):

Matthew A. Barbour ◽

Daniel J. Kliebenstein ◽

Jordi Bascompte

Keyword(s):

Genetic Diversity ◽

Food Web ◽

Allelic Variation ◽

Chemical Defenses ◽

Trophic Levels ◽

Raw Material ◽

Ecological Communities ◽

Warming Scenario ◽

The Face ◽

Loss Of Genetic Diversity

Genetic diversity provides the raw material for species to adapt and persist in the face of climate change. Yet, the extent to which these genetic effects scale at the level of ecological communities remains unclear. Here we experimentally test the effect of plant genetic diversity on the persistence of an insect food web under a current and future warming scenario. We found that plant genetic diversity increased food-web persistence by increasing the intrinsic growth rates of species across multiple trophic levels. This positive effect was robust to a 3°C warming scenario and resulted from allelic variation at two genes that control the biosynthesis of chemical defenses. Our results suggest that the ongoing loss of genetic diversity may undermine the persistence and functioning of ecosystems in a changing world.One Sentence SummaryThe loss of genetic diversity accelerates the extinction of inter-connected species from an experimental food web.

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Biodiversity Along Core–Periphery Clines

Biodiversity in Drylands ◽

10.1093/oso/9780195139853.003.0008 ◽

2005 ◽

Author(s):

Sergei Volis ◽

Salit Kark

Keyword(s):

Genetic Diversity ◽

Species Diversity ◽

Biological Diversity ◽

Morphological Diversity ◽

Spatial Location ◽

Convention On Biological Diversity ◽

Conservation Priorities ◽

Past Century ◽

Geographical Patterns ◽

Local Populations

The study of biodiversity has received wide attention in recent decades. Biodiversity has been defined in various ways (Gaston and Spicer, 1998, Purvis and Hector 2000, and chapters in this volume). Discussion regarding its definitions is dynamic, with shifts between the more traditional emphasis on community structure to emphasis on the higher ecosystem level or the lower population levels (e.g., chapters in this volume, Poiani et al. 2000). One of the definitions, proposed in the United Nations Convention on Biological Diversity held in Rio de Janeiro (1992) is “the diversity within species, between species and of ecosystems.” The within-species component of diversity is further defined as “the frequency and diversity of different genes and/or genomes . . .” (IUCN 1993) as estimated by the genetic and morphological diversity within species. While research and conservation efforts in the past century have focused mainly on the community level, they have recently been extended to include the within-species (Hanski 1989) and the ecosystem levels. The component comprising within-species genetic and morphological diversity is increasingly emphasized as an important element of biodiversity (UN Convention 1992). Recent studies suggest that patterns of genetic diversity significantly influence the viability and persistence of local populations (Frankham 1996, Lacy 1997, Riddle 1996, Vrijenhoek et al. 1985). Revealing geographical patterns of genetic diversity is highly relevant to conservation biology and especially to explicit decision-making procedures allowing systematic rather than opportunistic selection of populations and areas for in situ protection (Pressey et al. 1993). Therefore, studying spatial patterns in within-species diversity may be vital in defining and prioritizing conservation efforts (Brooks et al. 1992). Local populations of a species often differ in the ecological conditions experienced by their members (Brown 1984, Gaston 1990, Lawton et al. 1994). These factors potentially affect population characteristics, structure, and within-population genetic and morphological diversity (Brussard 1984, Lawton 1995, Parsons 1991). The spatial location of a population within a species range may be related to its patterns of diversity (Lesica and Allendorf 1995). Thus, detecting within-species diversity patterns across distributional ranges is important for our understanding of ecological and evolutionary (e.g., speciation) processes (Smith et al. 1997), and for the determination of conservation priorities (Kark 1999).

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