scholarly journals Intraspecific host variation plays a key role in virus community assembly

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Suvi Sallinen ◽  
Anna Norberg ◽  
Hanna Susi ◽  
Anna-Liisa Laine

Abstract Infection by multiple pathogens of the same host is ubiquitous in both natural and managed habitats. While intraspecific variation in disease resistance is known to affect pathogen occurrence, how differences among host genotypes affect the assembly of pathogen communities remains untested. In our experiment using cloned replicates of naive Plantago lanceolata plants as sentinels during a seasonal virus epidemic, we find non-random co-occurrence patterns of five focal viruses. Using joint species distribution modelling, we attribute the non-random virus occurrence patterns primarily to differences among host genotypes and local population context. Our results show that intraspecific variation among host genotypes may play a large, previously unquantified role in pathogen community structure.

2021 ◽  
Author(s):  
Vincent Calcagno ◽  
Nik Cunniffe ◽  
Frederic M Hamelin

Many methods attempt to detect species associations from co-occurrence patterns. Such associations are then typically used to infer inter-specific interactions. However, correlation is not equivalent to interaction. Habitat heterogeneity and out-of-equilibrium colonization histories are acknowledged to cause species associations even when inter-specific interactions are absent. Here we show how classical metacommunity dynamics, within a homogeneous habitat at equilibrium, can also lead to statistical associations. This occurs even when species do not interact. All that is required is patch disturbance (i.e. simultaneous extinction of several species in a patch) a common phenomenon in a wide range of real systems. We compare direct tests of pairwise independence, matrix permutation approaches and joint species distribution modelling. We use mathematical analysis and example simulations to show that patch disturbance leads all these methods to produce characteristic signatures of spurious association from "null" co-occurrence matrices. Including patch age (i.e. the time since the last patch disturbance event) as a covariate is necessary to resolve this artefact. However, this would require data that very often are not available in practice for these types of analyses. We contend that patch disturbance is a key (but hitherto overlooked) factor which must be accounted for when analysing species co-occurrence.


Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 470
Author(s):  
Martha Charitonidou ◽  
Konstantinos Kougioumoutzis ◽  
John M. Halley

Climate change is regarded as one of the most important threats to plants. Already species around the globe are showing considerable latitudinal and altitudinal shifts. Helen’s bee orchid (Ophrys helenae), a Balkan endemic with a distribution center in northwestern Greece, is reported to be expanding east and southwards. Since this southeastern movement goes against the usual expectations, we investigated via Species Distribution Modelling, whether this pattern is consistent with projections based on the species’ response to climate change. We predicted the species’ future distribution based on three different climate models in two climate scenarios. We also explored the species’ potential distribution during the Last Interglacial and the Last Glacial Maximum. O. helenae is projected to shift mainly southeast and experience considerable area changes. The species is expected to become extinct in the core of its current distribution, but to establish a strong presence in the mid- and high-altitude areas of the Central Peloponnese, a region that could have provided shelter in previous climatic extremes.


2021 ◽  
pp. 132-141
Author(s):  
Ashish Kumar Jangid

The Short-tailed ground agama or Hardwicke’s bloodsucker Calotes minor (Hardwicke & Gray, 1827) is known to occur in the Indian subcontinent and is largely confined to arid to semiarid environments, such as hard barren desert and abandoned fields. The precise distribution of this species is largely unknown to date, with few locality records spread biogeographically across Eastern Pakistan, Central and Western India. To improve on the existing spatial knowledge on this species and assess the ability to predict species distributions for taxa with few locality records, we studied the distribution of C. minor using a species distribution modelling framework. Our study allowed us to predict the distribution range of C. minor and help define a niche for this habitat-specific species. Highly probable habitats for C. minor were arid and semi-arid dryland habitats, characterised by plains or less rugged terrain with moderately narrow temperature range, lower aridity index, moderate to low vegetation index, and wide precipitation range. Furthermore, we report four additional occurrence records of C. minor from central Rajasthan.


2018 ◽  
Vol 373 (1761) ◽  
pp. 20170446 ◽  
Author(s):  
Scott Jarvie ◽  
Jens-Christian Svenning

Trophic rewilding, the (re)introduction of species to promote self-regulating biodiverse ecosystems, is a future-oriented approach to ecological restoration. In the twenty-first century and beyond, human-mediated climate change looms as a major threat to global biodiversity and ecosystem function. A critical aspect in planning trophic rewilding projects is the selection of suitable sites that match the needs of the focal species under both current and future climates. Species distribution models (SDMs) are currently the main tools to derive spatially explicit predictions of environmental suitability for species, but the extent of their adoption for trophic rewilding projects has been limited. Here, we provide an overview of applications of SDMs to trophic rewilding projects, outline methodological choices and issues, and provide a synthesis and outlook. We then predict the potential distribution of 17 large-bodied taxa proposed as trophic rewilding candidates and which represent different continents and habitats. We identified widespread climatic suitability for these species in the discussed (re)introduction regions under current climates. Climatic conditions generally remain suitable in the future, although some species will experience reduced suitability in parts of these regions. We conclude that climate change is not a major barrier to trophic rewilding as currently discussed in the literature.This article is part of the theme issue ‘Trophic rewilding: consequences for ecosystems under global change’.


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