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Large-scale prediction of seagrass distribution: the case of Cymodocea nodosa (Mediterranean-Atlantic)
Publication . Chefaoui, Rosa M.; Assis, J.; Duarte, C. M.; Serrão, Ester
Understanding the factors that affect seagrass meadows encompassing their entire
range of distribution is challenging yet important for their conservation. We model the
environmental niche of Cymodocea nodosa using a combination of environmental
variables and landscape metrics to examine factors defining its distribution and find
suitable habitats for the species. The most relevant environmental variables defining
the distribution of C. nodosa were sea surface temperature (SST) and salinity. We
found suitable habitats at SST from 5.8 ºC to 26.4 ºC and salinity ranging from 17.5 to
39.3. Optimal values of mean winter wave height ranged between 1.2 m and 1.5 m,
while waves higher than 2.5 m seemed to limit the presence of the species. The
influence of nutrients and pH, despite having weight on the models, was not so clear in
terms of ranges that confine the distribution of the species. Landscape metrics able to
capture variation in the coastline enhanced significantly the accuracy of the models,
despite the limitations caused by the scale of the study. By contrasting predictive
approaches, we defined the variables affecting the distributional areas that seem
unsuitable for C. nodosa as well as those suitable habitats not occupied by the species.
These findings are encouraging for its use in future studies on climate-related marine
range shifts and meadow restoration projects of these fragile ecosystems.
Can we use niche models of indicator species to predict the distribution of endangered communities?
Publication . Chefaoui, Rosa M.; Chozas, Sergio; Correia, Otilia; Santos, Ana M. C.; Hortal, Joaquín
European-wide conservation policies are based on the identification of priority habitats.
However, research on conservation biogeography often relies on the results and projections
of species distribution models to assess species' vulnerability to global change. We assess
whether the distribution and structure of threatened communities can be predicted by the
suitability of the environmental conditions for their indicator species. We present some
preliminary results elucidating if using species distribution models of indicator species at a
regional scale is a valid approach to predict these endangered communities. Dune plant
assemblages, affected by severe conditions, are excellent models for studying possible
interactions among their integrating species and the environment. We use data from an
extensive survey of xerophytic inland sand dune scrub communities from Portugal, one of
the most threatened habitat types of Europe. We identify indicator shrub species of different
types of communities, model their geographical response to the environment, and evaluate
whether the output of these niche models are able to predict the distribution of each type of
community in a different region.
Using niche modelling of indicator species to predict the distribution of xerophitic shrub dune communities in South-Western Portugal
Publication . Chefaoui, Rosa M.; Chozas, Sergio; Correia, Otilia; Santos, Ana M. C.; Hortal, Joaquín
Inland sand dune systems are amongst the most threatened habitat types of Europe.
Affected by severe conditions, these habitats present distinct community compositions,
which makes them excellent for studying possible interactions among their integrating
species and the environment. We focus on understanding the distribution and cooccurrence
of the species from dune plant assemblages as a key step for the adequate
protection of these habitats. Using data from an extensive survey we identified the
shrub species that could be considered indicators of the different xerophytic scrub dune
communities in South West Portugal. Then, we modelled the responses of these species
to the environmental conditions using Ecological Niche Factor Analysis. We present
some preliminary results elucidating whether using species distribution models of
indicator species at a regional scale is a valid approach to predict the distribution of the
different types of communities inhabiting these endangered habitats.
Environmental niche divergence among three dune shrub sister species with parapatric distributions
Publication . Chozas, Sergio; Chefaoui, Rosa; Correia, Otilia; Bonal, Raul; Hortal, Joaquín
Background and Aims The geographical distributions of species are constrained by their ecological requirements. The aim of this work was to analyse the effects of environmental conditions, historical events and biogeographical constraints on the diversification of the three species of the western Mediterranean shrub genus Stauracanthus, which have a parapatric distribution in the Iberian Peninsula. Methods Ecological niche factor analysis and generalized linear models were used to measure the response of all Stauracanthus species to the environmental gradients and map their potential distributions in the Iberian Peninsula. The bioclimatic niche overlap between the three species was determined by using Schoener's index. The genetic differentiation of the Iberian and northern African populations of Stauracanthus species was characterized with GenalEx. The effects on genetic distances of the most important environmental drivers were assessed through Mantel tests and non-metric multidimensional scaling. Key Results The three Stauracanthus species show remarkably similar responses to climatic conditions. This supports the idea that all members of this recently diversified clade retain common adaptations to climate and consequently high levels of climatic niche overlap. This contrasts with the diverse edaphic requirements of Stauracanthus species. The populations of the S. genistoides-spectabilis clade grow on Miocene and Pliocene fine-textured sedimentary soils, whereas S. boivinii, the more genetically distant species, occurs on older and more coarse-textured sedimentary substrates. These patterns of diversification are largely consistent with a stochastic process of geographical range expansion and fragmentation coupled with niche evolution in the context of spatially complex environmental fluctuations. Conclusions: The combined analysis of the distribution, realized environmental niche and phylogeographical relationships of parapatric species proposed in this work allows integration of the biogeographical, ecological and evolutionary processes driving the evolution of species adaptations and how they determine their current geographical ranges.
Successional dynamics in inland dune shrub communities drive changes in functional diversity
Publication . Chozas, Sergio; Correia, Otilia; Santos, Ana M. C.; Chefaoui, Rosa M.; Hortal, Joaquín
Communities can be defined as assemblages of species coexisting under particular
environments. The relationship between environment and species are regulated by
both environmental requirements –which ultimately determine the species capacity to
establish and survive in a particular environment– and the ecological interactions
occurring during assembly processes –which also determine community composition
by conditioning species coexistence. In this context, plant functional traits are
attributes that represent ecological strategies and determine how plants respond to
environmental factors and interact with other species. Therefore, the analysis of how
traits vary through the dynamics of communities, such as along successions, can give
insights about how environmental requirements and species interactions may
determine the composition and functional structure of these communities. The
xerophytic shrub communities inhabiting inland sand dunes in SW Portugal are
characterized by successional processes that are mainly driven by local (edaphic
gradients and human disturbance) and regional (climate) processes. Therefore, they
constitute an appropriate system for studying species interactions and environmentcommunity
co-variations based on functional terms. Using these communities as a
model, we evaluate the hypothesis that successional community changes in species
composition of xerophytic shrub communities can result in concurrent changes in
functional diversity
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
3599-PPCDT
Funding Award Number
EXPL/BIA-BIC/2311/2013