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Aim We studied global variation in beta diversity patterns of lake macrophytes using regional data from across the world. Specifically, we examined (1) how beta diversity of aquatic macrophytes is partitioned between species turnover and nestedness within each study region, and (2) which environmental characteristics structure variation in these beta diversity components. Location Global. Methods We used presence–absence data for aquatic macrophytes from 21 regions distributed around the world. We calculated pairwise‐site and multiple‐site beta diversity among lakes within each region using Sørensen dissimilarity index and partitioned it into turnover and nestedness coefficients. Beta regression was used to correlate the diversity coefficients with regional environmental characteristics. Results Aquatic macrophytes showed different levels of beta diversity within each of the 21 study regions, with species turnover typically accounting for the majority of beta diversity, especially in high‐diversity regions. However, nestedness contributed 30–50% of total variation in macrophyte beta diversity in low‐diversity regions. The most important environmental factor explaining the three beta diversity coefficients (total, species turnover and nestedness) was elevation range, followed by relative areal extent of freshwater, latitude and water alkalinity range. Main conclusions Our findings show that global patterns in beta diversity of lake macrophytes are caused by species turnover rather than by nestedness. These patterns in beta diversity were driven by natural environmental heterogeneity, notably variability in elevation range (also related to temperature variation) among regions. In addition, a greater range in alkalinity within a region, likely amplified by human activities, was also correlated with increased macrophyte beta diversity. These findings suggest that efforts to conserve aquatic macrophyte diversity should primarily focus on regions with large numbers of lakes that exhibit broad environmental gradients.
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Global variation in the beta diversity of
lake macrophytes is driven by
environmental heterogeneity rather
than latitude
Janne Alahuhta
* , Sarian Kosten
, Munemitsu Akasaka
Dominique Auderset
, Mattia M. Azzella
, Rossano Bolpagni
Claudia P. Bove
, Patricia A. Chambers
, Eglantine Chappuis
John Clayton
, Mary de Winston
, Frauke Ecke
, Esperanc
ßa Gacia
Gana Gecheva
, Patrick Grillas
, Jennifer Hauxwell
, Seppo Hellsten
Jan Hjort
, Mark V. Hoyer
, Christiane Ilg
, Agnieszka Kolada
Minna Kuoppala
, Torben Lauridsen
,EnHua Li
, Bal
azs A. Luk
Marit Mjelde
, Alison Mikulyuk
, Roger P. Mormul
, Jun Nishihiro
Beat Oertli
, Laila Rhazi
, Mouhssine Rhazi
, Laura Sass
Christine Schranz
, Martin Søndergaard
, Takashi Yamanouchi
, Qing
, Haijun Wang
, Nigel Willby
, XiaoKe Zhang
and Jani Heino
Geography Research Unit, University of
Oulu, PO Box 3000, FI90014 Oulu, Finland,
Department of Aquatic Ecology and
Environmental Biology, Institute for Water
and Wetland Research, Radboud University,
Heyendaalseweg 135, 6525AJ Nijmegen, The
Institute of Agriculture, Tokyo
University of Agricultural and Technology, 3
58 Saiwaicho, Fuchu, Tokyo 1838509, Japan,
Department F.-A. Forel for Environmental
and Aquatic Sciences, University of Geneva,
Bd Carl Vogt 66, CH 1205 Geneva,
Department of Life and
Environmental Sciences, University of
Cagliari, Viale S. Ignazio da Laconi 111113,
09123 Cagliari, Italy,
Department of
Chemistry, Life Sciences and Environmental
Sustainability, University of Parma, Parco
Area delle Scienze 11/A, 43124 Parma, Italy,
Departamento de Bot^
anica, Museu Nacional,
Universidade Federal do Rio de Janeiro,
Quinta da Boa Vista, 20940040 Rio de
Janeiro, RJ, Brazil,
Environment and
Climate Change Canada, 867 Lakeshore Rd,
Burlington, ON L7S 1A1, Canada,
d’Estudis Avanc
ßats de Blanes (CEAB),
Consejo Superior de Investigaciones Cient
(CSIC), C/ Acc
es a la Cala St. Francesc 14,
17300 Blanes, Spain,
Hepia, University of
Applied Sciences and Arts Western Switzerland,
150 route de Presinge, CH1254 Jussy/Gen
National Institute of Water and
Atmospheric Research Limited, PO Box 11115,
Hamilton, New Zealand,
Department of
Aquatic Sciences and Assessment, Swedish
Aim We studied global variation in beta diversity patterns of lake macrophytes
using regional data from across the world. Specifically, we examined (1) how
beta diversity of aquatic macrophytes is partitioned between species turnover
and nestedness within each study region, and (2) which environmental charac-
teristics structure variation in these beta diversity components.
Location Global.
Methods We used presenceabsence data for aquatic macrophytes from 21 regions
distributed around the world. We calculated pairwise-site and multiple-site beta
diversity among lakes within each region using Sørensen dissimilarity index and par-
titioned it into turnover and nestedness coefficients. Beta regression was used to cor-
relate the diversity coefficients with regional environmental characteristics.
Results Aquatic macrophytes showed different levels of beta diversity within each
of the 21 study regions, with species turnover typically accounting for the majority
of beta diversity, especially in high-diversity regions. However, nestedness con-
tributed 3050% of total variation in macrophyte beta diversity in low-diversity
regions. The most important environmental factor explaining the three beta diver-
sity coefficients (total, species turnover and nestedness) was elevation range, fol-
lowed by relative areal extent of freshwater, latitude and water alkalinity range.
Main conclusions Our findings show that global patterns in beta diversity of lake
macrophytes are caused by species turnover rather than by nestedness. These patterns
in beta diversity were driven by natural environmental heterogeneity, notably vari-
ability in elevation range (also related to temperature variation) among regions. In
addition, a greater range in alkalinity within a region, likely amplified by human
activities, was also correlated with increased macrophyte beta diversity. These findings
suggest that efforts to conserve aquatic macrophyte diversity should primarily focus
on regions with large numbers of lakes that exhibit broad environmental gradients.
alkalinity range, aquatic plants, elevation range, freshwater ecosystem,
hydrophytes, latitude, nestedness, spatial extent, species turnover
ª2017 John Wiley & Sons Ltd 1
Journal of Biogeography (J. Biogeogr.) (2017)
University of Agricultural Sciences (SLU), PO Box 7050, SE750 07 Uppsala, Sweden,
Department of Wildlife, Fish, and Environmental Studies,
Swedish University of Agricultural Sciences (SLU), SE901 83 Ume
a, Sweden,
Faculty of Biology, University of Plovdiv, Plovdiv 4000, Bulgaria,
Tour du Valat, Research Institute for the conservation of Mediterranean wetlands, Le Sambuc 13200 Arles, France,
Center for Limnology,
University of Wisconsin, 680 N Park St., Madison, WI 53704, USA,
Finnish Environment Institute, Freshwater Centre, PO Box 413, FI90014
Oulu, Finland,
Fisheries and Aquatic Sciences, School of Forest Resources and Conservation, Institute of Food and Agricultural Services,
University of Florida, 7922 NW 71st Street, Gainesville, FL 32609, USA,
Department of Freshwater Assessment Methods and Monitoring,
Institute of Environmental ProtectionNational Research Institute, Warsaw, Poland,
Department of Bioscience, Aarhus University, Vejsøvej 25,
8600 Silkeborg, Denmark,
Key Laboratory for Environment and Disaster Monitoring and Evaluation of Hubei Province, Institute of Geodesy
and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China,
Department of Tisza River Research, MTA Centre for Ecological
Research, Bem t
er 18/C, H4026 Debrecen, Hungary,
Norwegian Institute for Water Research (NIVA), Gaustadall
een 21, 0349 Oslo, Norway,
Wisconsin Department of Natural Resources, 2801 Progress Rd., Madison, WI 53716, USA,
Department of Biology, Research Group in
Limnology, Ichthyology and Aquaculture—Nupe
´lia, State University of Maringa
´, Av. Colombo 5790, Bloco H90, CEP–87020–900 Mringa
Faculty of Sciences, Toho University, 2–2–1 Miyama, Funabashi Chiba 274–8510, Japan,
Laboratory of Botany, Mycology and
Environment, Faculty of Sciences, Mohammed V University in Rabat, 4 avenue Ibn Battouta B.P. 1014 RP, Rabat, Morocco,
Department of
Biology, Faculty of Science and Technology, Moulay Ismail University, PB 509 Boutalamine Errachidia, Morocco,
Illinois Natural History
Survey, Prairie Research Institute, University of Illinois, 1816 South Oak Street, Champaign, IL 61820, USA,
Bavarian Environment Agency,
Demollstraße 31, 82407 Wielenbach, Germany,
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology,
Chinese Academy of Sciences, Wuhan 430072, China,
University of Chinese Academy of Sciences, Beijing 100049, China,
Biological and
Environmental Science, University of Stirling, Stirling FK9 4LA, UK,
School of Life Sciences, Anqing Normal University, Anqing 246011, China,
Finnish Environment Institute, Natural Environment Centre, Biodiversity, PO Box 413, FI–90014 Oulu, Finland
*Correspondence: Janne Alahuhta, Geography Research Unit, University of Oulu, PO Box 3000, FI90014 Oulu, Finland.
Understanding broad-scale biodiversity patterns has become
a fundamental topic in biogeography and ecology. The
importance of explaining these patterns has increased in
recent years because they are intimately related to, for exam-
ple, ecosystem functioning (Symstad et al., 2003) and resili-
ence (Folke et al., 2004), biogeographical regionalization
(Divisek et al., 2016), niche conservatism (Alahuhta et al.,
2017), species conservation (Brooks et al., 2008) and ecosys-
tem services (Naidoo et al., 2008). Spatial variation in
broad-scale diversity patterns is typically driven by natural
history (e.g. past dispersal barriers and evolutionary
changes), interactions among species (e.g. competition, pre-
dation and mutualism) and biogeography (e.g. distribution
of climate zones, productivity and habitat heterogeneity)
(Willig et al., 2003; Qian & Ricklefs, 2007; Soininen et al.,
2007; Field et al., 2009; Baselga et al., 2012). Better knowl-
edge of patterns in biodiversity and their basis is also critical
for managing and adapting to invasive species, land use
changes, landscape and habitat degradation, and increasing
temperatures associated with global change (V
et al., 2010, Vilmi et al., 2017). Therefore, studies focussing
on broad-scale diversity patterns may directly advance both
basic and applied research.
One intrinsic component of biodiversity is beta diversity
(i.e. among-site differences in species composition). In gen-
eral, beta diversity indicates the spatial variation of species
composition among communities across space (Anderson
et al., 2011), and is essentially related to two processes
(Baselga, 2010): species replacement (i.e. turnover, where
one species replaces another with no change in richness)
and nestedness (i.e. species richness differences due to spe-
cies gain or loss). Mechanisms responsible for species
replacement originate from environmental filtering, compe-
tition and historical events (Melo et al., 2009; Kraft et al.,
2011; Wen et al., 2016). Conversely, nestedness differences
stem from species thinning or from other ecological pro-
cesses (Baselga, 2010; Legendre, 2014), such as physical bar-
riers or human disturbance, that result in species-poor sites
being a subset of the richest site in the region. Independent
of the dissimilarity measure used to represent beta diversity,
it has been reported to decrease with latitude and increase
with elevation and area (Jones et al., 2003; Heegaard, 2004;
Qian & Ricklefs, 2007; Soininen et al., 2007; Kraft et al.,
2011). Explanations for these patterns in beta diversity stem
from effects of energy availability, waterenergy dynamics,
climatic variability, habitat heterogeneity and human distur-
bance (Gaston, 2000; Willig et al., 2003; Socolar et al.,
2016). However, the majority of studies on beta diversity
have been conducted at small spatial extents or using coarse
resolution data across broad spatial scales (Kraft et al.,
2011; Dobrovolski et al., 2012), exposing the lack of beta
diversity studies using fine-resolution data at regional and
global scales.
Increasing evidence indicates, however, that patterns in
beta diversity depend on the studied ecosystem, organisms
and geographical location (Soininen et al., 2007; Dobrovolski
et al., 2012; Viana et al., 2015; Wen et al., 2016). Many of
the reported patterns in beta diversity concern well-known,
and often charismatic, taxa of terrestrial ecosystems (Qian &
Ricklefs, 2007; Melo et al., 2009; Kraft et al., 2011; Wen
Journal of Biogeography
ª2017 John Wiley & Sons Ltd
J. Alahuhta et al.
et al., 2016) but may be unrepresentative of patterns in beta
diversity for organisms in other ecosystems (Soininen et al.,
2007). Studies of beta diversity in freshwaters have often
proved to be incongruent with those of terrestrial assem-
blages (Heino, 2011; Hortal et al., 2015). A few studies have
suggested that ecological factors or data set properties associ-
ated with freshwater communities may override spatial pro-
cesses in determining beta diversity (Heino et al., 2015;
Viana et al., 2015). One possible explanation for these differ-
ences is that terrestrial ecosystems are more directly influ-
enced by climate, whereas water temperatures, which are
naturally more important to aquatic organisms, are more
stable. Moreover, the physiological constraints of access to
water and atmospheric gases are fundamentally different for
terrestrial and aquatic organisms. Consequently, there is a
need to study diversity patterns of freshwater assemblages at
regional and global scales to discover whether they follow the
general trends evident in terrestrial organisms.
Aquatic macrophytes are among the most under-repre-
sented groups in broad-scale studies of freshwater biodiver-
sity, yet they are an integral structural and functional
component of freshwater ecosystems (Chambers et al., 2008).
Few studies on macrophyte diversity have been conducted at
continental or global extents, and these have relied on data
scaled to coarse political or biogeographic regions (Chambers
et al., 2008; Chappuis et al., 2012), leading to potentially
spurious conclusions about species distributions at finer
scales (Hortal et al., 2015). Although aquatic macrophyte
diversity has been actively studied at local and regional
extents, these studies may suffer from ecosystem-specific
characteristics (i.e. varying environmental gradients lead spe-
cies to respond differently to abiotic factors among regions),
including variation in underlying environmental gradients
among regions (Heino et al., 2015; Viana et al., 2015). For
example, aquatic macrophyte diversity studied using similar
methods showed a clear decreasing latitudinal gradient in
one region, yet a reversed latitudinal gradient in another
(Alahuhta et al., 2013; Alahuhta, 2015). Thus, explaining and
testing hypotheses related to broad-scale patterns in diversity
is difficult with one or a few data sets, and a more general
overview demands comparative analysis of multiple data sets
(Crow, 1993; Kraft et al., 2011; Heino et al., 2015).
In this study, we examine pairwise- and multiple-site beta
diversity of aquatic macrophytes using data sets for 21
regions from around the world. Specifically, we consider two
questions: (1) How is beta diversity of aquatic macrophytes
partitioned between species turnover and nestedness across
study regions on a global scale? (2) Which environmental
factors explain variation in these beta diversity components
for aquatic macrophytes across study regions? Based on a
continental scale study (Viana et al., 2015), we expected that
spatial turnover accounts for most of the overall beta diver-
sity. We also assumed that latitude does not strongly struc-
ture macrophyte beta diversity (Crow, 1993; Chambers et al.,
2008). Instead, we hypothesized that macrophyte beta diver-
sity is mostly explained by variables reflecting variation in
local habitat conditions, thus indicating the effect of environ-
mental heterogeneity on beta diversity (Heegaard, 2004;
Viana et al., 2015).
Macrophyte and explanatory variable data
We compiled lake macrophyte data for 21 regions with vari-
able sizes from around the world (Fig. 1). Although only one
or a few regions are included from some continents (e.g.
only Morocco from Africa), our data set covered all major
Paraná River
Salga (Brazil, Uruguay
and Argentina)
US state of Florida
US state of Minnesota
US state of Wisconsin
New Zealand
Switzerland Hungary
Figure 1 Study regions are represented in blue circles situated in the middle of convex hulls (n=21). Crosses in the right side panel
indicate which latitudinal bands are covered in our work.
Journal of Biogeography
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Beta diversity of aquatic macrophytes
continents inhabitable by aquatic macrophytes (see Cham-
bers et al., 2008). The regions either closely but not entirely
followed a country’s political border (e.g. Finland and New
Zealand), or were delineated based on natural features (e.g.
the Paran
a River basin in Brazil and a small area in the
Nord-Trøndelag county of Norway). The lakes consisted
mostly of natural lentic water bodies (i.e. reservoirs were
excluded), but were influenced by anthropogenic pressures
to varying degrees (e.g. nutrient enrichment, introduced spe-
cies, water level fluctuation, isolation and fish farming). The
data consisted of presenceabsence of vascular macrophyte
species that grow exclusively in freshwaters (i.e. hydro-
phytes). The species data were based on empirical or scien-
tific surveys which were performed all or in part by the
authors, with the exception of Canada, China and Japan
where data were compiled from existing literature (A list of
the data sources for two of these regions is found in
Appendix 1, Appendix S1 in Supporting Information).
Macrophytes were surveyed using broadly the same methods
within each region, enabling us to compare beta diversity
patterns across regions and to minimize the potential nega-
tive effects caused by contrasting regional survey methods.
The surveys were executed mostly between 1990 and 2012,
with the exception of Canada, China and Britain, where sur-
veys were done during 1970s and 1980s, between 1964 and
2014, and between 1980 and 1998, respectively.
We used convex hulls to delineate the minimal area con-
taining all survey locations within a region (see Appendix S2,
Heino et al., 2015). We then used the convex hulls to extract
environmental information for each region and calculated
mean and range values, depending on the variable in ques-
tion, for each of the 21 regions.
The explanatory variables calculated for each regional
convex hull included region spatial extent (km
), elevation
range (m, Hijmans et al., 2005), modelled alkalinity range
in lakes (mequiv. l
at 1/16 degrees resolution, Marc
et al., 2015), predicted range of soil organic carbon mass
fraction at depth of 1 m (1 km resolution, Hengl et al.,
2014), areal extent of freshwaters expressed as a proportion
of region spatial extent, herein referred to as proportion of
freshwater (%, 1 km resolution, Latham et al., 2014) and
latitude (i.e. coordinate Yoriginated from each region’s
centre point) (Table 1). In addition, we examined whether
areal extent of artificial surfaces (e.g. surfaces with houses,
roads or industrial sites, Latham et al., 2014) as a propor-
tion of region spatial extent (%), was correlated with the
beta diversity coefficients and other explanatory variables.
Regional spatial extent was a surrogate for sampling effort,
as it was strongly positively associated with both numbers
of lakes and number of species present within a region
0.64, P<0.001, see Appendix S3), but is also
an indicator of environmental heterogeneity (see also Gas-
ton, 2000). In addition, elevation range likely illustrates
variability in habitats suitable for different macrophytes
(Gaston, 2000; Melo et al., 2009), and it simultaneously
served as a proxy for variation in temperature (correlation
Table 1 Explanatory variables used in the study and the number of lakes and species within each region. Negative latitude (Y) values
were converted to positive in the analysis to strengthen the relationship between beta diversity coefficients and latitude. Extent: spatial
extent of a region, Organic C: soil organic carbon range, waters: areal extent of water within a region as proportion of total spatial
extent, Y: latitude.
of lakes
Number of
Alkalinity range
(mequiv. l
range (m)
Organic C
(mass fraction) Waters (%) Y
Brazil, Amazon 21 27 0.01 603 943 4 0.23 6.23
Brazil, Parana River 29 37 0.79 17 368 18 21.08 22.78
Canada 58 82 3.95 242 82,540 33 21.72 44.78
China 36 100 4.75 1374 151,400 20 13.36 30.78
Denmark 32 77 4.33 156 17,260 30 10.67 56.08
Finland 261 98 3.55 923 315,900 110 10.50 64.32
Hungary 50 39 0.59 375 25,740 12 1.56 47.28
Italy 22 60 4.04 3637 37,980 20 2.20 44.68
Japan 49 93 3.20 3683 216,600 28 1.40 38.24
Morocco 33 54 4.33 2322 36,520 7 0.51 34.18
New Zealand 205 88 4.58 2800 250,800 48 22.16 41.10
Norway 30 30 0.00 309 724 17 23.01 64.90
Poland 475 84 4.34 289 175,000 22 1.99 52.99
Salga project (Brazil, Uruguay
and Argentina)
67 28 3.63 2119 299,300 57 3.88 32.98
Spain 66 56 4.67 3129 34,480 19 2.98 42.04
Sweden 379 101 4.68 1853 403,600 68 10.99 62.24
Switzerland 92 60 3.18 3633 26,910 35 4.93 46.93
UK 1928 127 4.81 1219 174,000 81 2.28 54.24
US state of Florida 205 57 4.45 112 104,200 66 5.14 28.99
US state of Minnesota 441 65 4.31 477 152,700 58 7.09 46.26
US state of Wisconsin 409 102 3.93 397 141,900 22 5.62 44.72
Journal of Biogeography
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J. Alahuhta et al.
with temperature range: R
=0.92, P<0.001). Elevation
range was also positively associated with mean altitude
=0.73, P<0.001). Following Dormann et al. (2013),
multicollinearity was manifested at the level of R
|> 0.7|
and, in these cases, statistically less significant predictors of
beta diversity were excluded from final models (see
Appendix S2). Carbon compounds in water directly and
indirectly influence macrophytes (Alahuhta & Heino, 2013;
Kolada et al., 2014). We therefore used two different prox-
ies, water alkalinity and soil organic carbon, to represent
these local-scale components. Carbon dioxide and bicarbon-
ate concentration influence photosynthesis in aquatic
macrophytes, while organic carbon (i.e. carbon leached
from organic soils) absorbs light, a common constraint on
productivity (Madsen et al., 1996; Vestergaard & Sand-Jen-
sen, 2000). Water alkalinity is also affected by anthro-
pogenic land use (e.g. Vestergaard & Sand-Jensen, 2000;
Kolada et al., 2014), enabling us to infer the degree of
anthropogenic pressures on macrophyte beta diversity in
lakes located on homogenous geology but lacking lake-level
chemistry data. The relative areal extent of freshwaters
within a region was used to indicate availability of potential
habitat for macrophyte growth. Finally, changes in species
diversity with latitude are well known, with species diversity
often decreasing towards the Poles (Qian & Ricklefs, 2007).
Negative latitude values were converted to positive in our
analysis to compensate for limited data availability on
Southern Hemisphere regions, thereby strengthening the
relationship between macrophyte beta diversity and latitude.
Beta diversity coefficients for different data sets
We determined beta diversity of aquatic macrophytes using
pairwise-site and multiple-site indices based on presenceab-
sence species data within a region. In our study, the pair-
wise-site index indicated degree of absolute beta diversity
within each region, whereas the multiple-site index was used
to compare relative differences in beta diversity among
regions (Baselga, 2010). For both indices, the calculations
were based on the Sørensen dissimilarity, resulting in the fol-
lowing three dissimilarity coefficients: (1) Sørensen coeffi-
cient (i.e. a measure of overall beta diversity, b
), (2)
Simpson coefficient (i.e. a measure of turnover immune to
nestedness resulting from species richness differences, b
), and (3) a coefficient measuring nestednessresultant
beta diversity (b
, Baselga, 2010; Legendre, 2014). The
Simpson coefficient defines species turnover without the
influence of richness gradients, whereas the nestedness-resul-
tant component of beta diversity is the direct difference
between b
and b
. For the pairwise-site index, we
averaged the pairwise dissimilarities between all lakes in a
region. Because the number of sites affects the multiple-site
index (Baselga, 2010), we resampled the 21 regional data sets
to standardize them to a common number of 21 lakes, the
minimum number of lakes found across the regional data
sets (in Brazil Amazon, Table 2), based on 1000 permuta-
tions in each region. Both beta diversity indices were
obtained using the R package ‘betapart’ (Baselga et al.,
2013). The three beta diversity coefficients were calculated
Table 2 Summary of best models explaining variation in aquatic macrophyte beta diversity for multiple-site and pairwise dissimilarities
within a region. Models were calculated for Sørensen dissimilarity (total beta diversity), Simpson dissimilarity (beta diversity due to
turnover) and nestedness dissimilarity (beta diversity due to nestedness-resultant richness differences). Best models with delta <2 are
presented, because these models are typically considered to have similar statistical support (Burnham & Anderson, 2002). Waters:
Proportion of water within a region, d.f.: degree of freedom, delta: AICc difference between model iand the model with the smallest
AICc, weight: Akaike weight, pseudo R
: maximum likelihood coefficients of determination were obtained through an iterative process.
AICc d.f. DAICc Weight Pseudo R
Multiple-site beta diversity
Elevation range 80.9 3 0 0.435 0.282
Elevation range +latitude 79.6 4 1.34 0.223 0.317
Elevation range +waters 79.1 4 1.74 0.182 0.326
Elevation range +alkalinity range 78.9 4 1.99 0.160 0.309
Species turnover
Elevation range 57.2 3 0 0.708 0.325
Elevation range +waters 55.4 4 1.77 0.292 0.366
Elevation range 83.9 3 0 1 0.280
Pairwise-site beta diversity
Elevation range 21.9 3 0 0.719 0.283
Elevation range +Latitude 20.0 4 1.88 0.281 0.301
Species turnover
Elevation range 14.7 3 0 1 0.326
Elevation range 62.8 3 0 1 0.269
Journal of Biogeography
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Beta diversity of aquatic macrophytes
using the functions beta.pair and beta.sample for pairwise-
site and multiple-site indices, respectively.
Statistical analysis
We used beta regression to identify which predictor variables
explained beta diversity of aquatic macrophytes across the 21
regions. Beta regression, which is an extension of generalized
linear models (GLM), was developed for situations where the
dependent variable is measured continuously on a standard
unit interval between 0 and 1 (Cribari-Neto & Zeileis, 2010).
The models are based on beta distribution with parameteri-
zation using mean and precision parameters. Similar to
GLMs, the expected mean is linked to the responses through
a link function and a linear predictor. The purpose of the
link function is to stabilize the error variance and transform
the fitted values to the desired application range (Ferrari &
Cribari-Neto, 2004). Linear regression using a logit-trans-
formed response variable is still commonly employed to
analyse the type of response data considered in our work.
However, this is questionable, because it (1) may yield fitted
values for the variable of interest that exceed its theoretical
lower and upper bounds, (2) does not allow parameter inter-
pretation in terms of the response on the original scale, and
(3) measures proportions typically displaying asymmetry
and, hence, inference based on the normality assumption can
be misleading (Ferrari & Cribari-Neto, 2004). We therefore
used beta regression models with a logistic link function,
which is asymptotic in the range 01 (i.e. the predicted val-
ues are automatically in the desired application range).
The models with the most important explanatory variables
influencing the beta diversity coefficients were selected based
on the second order Akaike information criterion corrected
for small sample size (AICc) among all model combinations.
AICc takes into account sample size by increasing the relative
penalty for model complexity with small data sets, and its
use is recommended if, as in our case, the ratio between
sample size and model parameters is <40 (Burnham &
Anderson, 2002). We also examined the possibility of curvi-
linear relationships between beta diversity coefficients and
certain explanatory variables (i.e. region extent, organic car-
bon and latitude) by entering the quadratic terms of these
variables in our models, making the use of AICc even more
relevant. In addition, we calculated AIC differences, which
can be used to rank different models in order of importance
AICmin, with AIC
representing the best model with
respect to expected Kullback-Leibler information lost).
Akaike weights derived from AIC differences were estimated
for each model to extract additional information on model
ranking. We also present pseudo R
values, which are a
squared correlation of linear predictor and link-transformed
response and have the same scale as R
values (between 0
and 1) (Ferrari & Cribari-Neto, 2004). The relative impor-
tance of explanatory variables was evaluated by summing the
Akaike weights of the models in which a given variable
appears from the exhaustive list of models. A value of <2.0
was used as the threshold for deviation of AICc values
among candidate models (i.e. difference between model i
and the model with the smallest AICc, DAICc), because
models with AICc differing by <2.0 are typically considered
to have similar statistical support (Burnham & Anderson,
All statistical analyses were conducted in R 3.2.0 (R Core
Team 2015). Beta regression was performed using functions
in the R package ‘betareg’ (Cribari-Neto & Zeileis, 2010),
and candidate models were selected with the R package
‘MuMIn’ (Barton, 2014).
Beta diversity of aquatic macrophytes differed among the 21
study regions, a finding that was mostly attributable to spe-
cies turnover (Fig. 2), especially in high-beta diversity
regions, and applied to both pairwise and multiple-site
indices. Nestedness accounted only for a small fraction of
overall beta diversity (14% of pairwise-site dissimilarity on
average) and was most important (although still less than
species turnover) in regions with low overall pairwise-site
beta diversity. Macrophyte beta diversity patterns in the
majority of regions were thus explained by variation in
species composition among lakes, rather than differences in
species richness. Based on the pairwise-site index, the degree
of macrophyte beta diversity varied clearly among the 21
study regions. The greatest beta diversity was found in the
coastal South American lakes (Salga, 0.90) and Spain (0.92),
whereas values were lowest in both the Brazilian regions
(0.430.44) and China (0.43). The top models obtained
through beta regression explained similar amounts of varia-
tion and included the same important explanatory variables
(Table 2) for both pairwise-site and multiple-site beta diver-
sity indices. The best models accounted for 2833% of varia-
tion in the Sørensen coefficient, 3337% in the turnover
component and 2728% in the nestedness component.
The most important explanatory variables for all the best
models across the two beta diversity indices and different
coefficients were elevation range (Fig. 3, see Appendix S4),
proportion of freshwater, latitude range (Fig. 3, see
Appendix S4) and alkalinity range, yet their relative impor-
tance varied somewhat. We found that overall beta diversity
(i.e. Sørensen coefficient) and species turnover increased with
increasing elevation range, latitude and alkalinity range, and
decreased with increasing proportion of freshwater. The neg-
ative relation between species turnover and proportion of
freshwater is probably due to connectivity, which typically
increases with proportion of freshwaters, resulting in
enhanced exchange of macrophyte species among lakes,
thereby lowering turnover. Nestedness was negatively related
to the first three variables but was positively associated with
proportion of freshwater. Although some explanatory vari-
ables (i.e. spatial extent, latitude and organic carbon range)
showed a curvilinear relationship with beta diversity coeffi-
cients in preliminary analyses, only the linear terms of these
Journal of Biogeography
ª2017 John Wiley & Sons Ltd
J. Alahuhta et al.
variables were selected in the best models. Comparison
across all possible models showed that elevation range was
included in the majority of models, with proportion of fresh-
water, latitude and alkalinity range all being of secondary
importance (Table 3). By contrast, organic carbon and spa-
tial extent were weak predictors of beta diversity across the
In addition to relationships between beta diversity coeffi-
cients and environmental variability, certain environmental
variables were correlated with indicators of anthropogenic
pressures. Alkalinity range showed a positive relationship
with the relative areal extent of artificial surfaces as propor-
tion of region spatial extent (R
=0.46, P=0.04). Both alka-
linity range (R
=0.48, P=0.03) and temperature range
=0.56, P=0.008) were associated with spatial extent,
such that the span in alkalinity and temperature was greater
in regions that covered a greater areal extent. These correla-
tions also impede the separation of possible independent
effects for these factors.
Aquatic macrophytes exhibited considerable regional varia-
tion in beta diversity, which was largely driven by species
turnover. Our results thus suggest that turnover in species
composition primarily accounts for macrophyte beta diver-
sity. Aquatic macrophytes have similarly shown high levels of
species turnover at a regional and continental extent (Hee-
gaard, 2004; Viana et al., 2015; Boschilia et al., 2016). How-
ever, our finding conflicts with previous global extent studies
on beta diversity in which nestedness contributed equally or
more than species turnover to total diversity of amphibians
(Baselga et al., 2012), fish (Leprieur et al., 2011), macroin-
vertebrates (Heino et al., 2015) and oribatid mites (Gergocs
& Hufnagel, 2015). In addition, nestedness has been found
to outweigh species turnover in areas affected by glaciations
until recent time (Baselga et al., 2012; Dobrovolski et al.,
2012). We found no sign of this, as nestedness was typically
lowest in regions that were wholly or partly ice covered
Brazil, Amazon
Brazil, Paraná River
New Zealand
Salga project
US state of Florida
US state of Minnesota
US state of Wisconsin
Beta diversity
Beta diversity
Species turnover
Brazil, Amazon
Brazil, Paraná River
Finla nd
New Z ealand
Salga pr oject
Switzer land
US state of Florida
US state of Minn esota
US state of Wisconsin
Species tu rnover
Nestedn ess
Figure 2 Simpson dissimilarity (beta
diversity due to species turnover) and
nestedness dissimilarity (beta diversity due
to nestedness-resultant richness differences)
that sum to Sørensen dissimilarity (i.e. total
beta diversity) based on multiple site (a)
and mean of pairwise (b) beta diversity
measures for each study region. Multiple-
site beta diversity was based on 21
randomly selected lakes for each region
(except for Brazil, Amazon which had a
total nof 21).
Journal of Biogeography
ª2017 John Wiley & Sons Ltd
Beta diversity of aquatic macrophytes
during the last glaciation (e.g. Finland, Norway, Canada,
China, New Zealand, Switzerland, US state of Minnesota and
UK). Our study thus emphasizes that conclusions about glo-
bal patterns in beta diversity need verification across a
diverse range of organisms, instead of using only a few well-
studied terrestrial taxa, because variable patterns exist in nat-
ure and exceptions are as instructive as conformity.
Contrary to our a priori expectations based on trends
found in terrestrial taxa (Willig et al., 2003; Qian & Ricklefs,
2007; Soininen et al., 2007), beta diversity of aquatic
macrophytes increased (albeit weakly) towards the poles.
Based on Rapoport’s rule (Stevens, 1989), species ranges and
niche width should increase at higher latitudes, giving rise to
a decrease in beta diversity (Soininen et al., 2007). But, in
general, many aquatic assemblages do not exhibit the latitu-
dinal patterns observed for terrestrial taxa, such as mammals,
birds and vascular plants (Heino, 2011; Hortal et al., 2015).
Even regarding species richness, one of the most widely used
measures of diversity, aquatic macrophytes show differing
responses to latitude at continental and global scales
Mean elevation Elevation range Latitude
0 250 500 750 1000 0 1000 2000 3000 0 204060
Beta diversity
Sørensen Species turnover Nestedness
Figure 3 Relationships between pairwise-site beta diversity dissimilarities (i.e. Sørensen, species turnover and nestedness) of freshwater
macrophytes and mean altitude, elevation range and latitude. Similar plot for multiple-site beta diversity coefficients can be found in
Appendix S4.
Table 3 Relative importance (I) of explanatory variables among all model compilations. 1.00 indicates that the particular variable is
selected in all models, whereas 0 represents that the variable is not selected in any of the models. ‘+’ indicates positive and ‘’ negative
relation between the beta diversity coefficient and that environmental variable. If a given variable was not included among the most
important beta diversity models (AICc <2.0), then the direction of influence was obtained from a full model including all the candidate
variables. I: importance, D: direction of influence, elevation: elevation range, alkalinity: alkalinity range, extent: spatial extent of a region,
organic C: soil organic carbon range, waters: areal extent of water within a region as proportion of total spatial extent.
Multiple-site beta diversity Pairwise-site beta diversity
turnover Nestedness Sørensen
turnover Nestedness
Elevation 0.80 +0.90 +0.85 0.82 +0.90 +0.89
Waters 0.33 0.30 0.23 +0.26 0.25 0.17 +
Latitude 0.32 +0.24 +0.18 0.26 +0.21 +0.18
Alkalinity 0.25 +0.22 +0.20 0.24 +0.22 +0.17
Organic C 0.16 0.19 0.20 0.16 0.16 +0.17
Extent 0.16 0.17 0.20 0.16 0.16 0.17 +
Journal of Biogeography
ª2017 John Wiley & Sons Ltd
J. Alahuhta et al.
(Rørslett, 1991; Chambers et al., 2008; Chappuis et al.,
2012). In addition, contrasting latitudinal patterns in macro-
phyte beta diversity have been found within individual
regions (Heegaard, 2004; Viana et al., 2015), likely due to
different study scales and varying sampling techniques used.
Our study included only macrophyte data collected via con-
sistent methods (within each region) and showed that overall
beta diversity increases weakly from the equator towards the
poles. However, the relative importance of latitude in
explaining global macrophyte beta diversity was modest,
being selected only in two of eleven models. These two mod-
els concerned the overall (Sørensen) beta diversity. In con-
trast, species turnover and nestedness did not vary
consistently with latitudinal gradient. This is likely because
aquatic macrophytes are more responsive to local environ-
mental conditions than the broad-scale variation in climate
that underlies latitudinal gradients in the beta diversity of
other (terrestrial) organism groups. Aquatic environments
moderate extreme climatic conditions, leading to less varia-
tion in temperature in freshwater than terrestrial ecosystems,
and this may partly explain the conflict in latitudinal beta
diversity patterns between freshwater and terrestrial assem-
Although the relationship between latitude and macrophyte
beta diversity conflicted with that of many organisms, our
results support another reported beta diversity pattern. Habi-
tat heterogeneity has previously been shown to structure beta
diversity for terrestrial plants (Freestone & Inouye, 2006) and
butterflies at a regional extent (Andrew et al., 2012), birds
and mammals at a continental extent (Melo et al., 2009), and
oceanic bacteria (Zinger et al., 2011) and fish (Leprieur et al.,
2011) at a global extent. Variation in macrophyte beta diver-
sity in our study regions was predominantly determined by
environmental heterogeneity, primarily the degree of eleva-
tion variability (also correlated with temperature variability)
in a region. Thus, beta diversity of aquatic macrophytes (ex-
pressed as either multiple-site or pairwise-site diversity)
increased with variation in altitude. This positive association
between beta diversity and elevation range likely reflects the
greater variety of habitats or resources available with greater
variation in altitude. Wang et al. (2012) similarly found that
elevational beta diversity of aquatic micro- and macroorgan-
isms was primarily related to environmental heterogeneity at
a regional extent. Species distributions are typically con-
strained by harsh climatic conditions at high elevation (Gas-
ton, 2000), and various aspects of macrophyte physiology are
known to be temperature sensitive (Sculthorpe, 1967; Rooney
& Kalff, 2000). However, the buffering of temperature
extremes in aquatic environments allows for continued plant
growth over a wide elevation range. Greater variation in habi-
tats with increasing variation in elevation is also related to
geological and soil properties, as low-lying lakes will vary
more in water chemistry due to greater variation in soil and
geology, which in turn increase variation in water chemistry
(Wang et al., 2012), as well as from the added influence of
human activity. These factors magnify the elevation gradient
which enhances environmental heterogeneity and thus enables
the establishment of a greater variety of macrophyte species,
further increasing beta diversity within a region.
Regional variation in water alkalinity, soil organic carbon
availability and spatial extent further indirectly would have
supported the habitat heterogeneity hypothesis in explaining
global patterns of macrophyte beta diversity. However, con-
trary to our expectations, these individual variables were not
important predictors of macrophyte beta diversity. Alkalinity
and soil organic carbon influence aquatic macrophytes
through their differing ability to use bicarbonate or carbon
dioxide as a source of carbon in photosynthesis (Madsen
et al., 1996), but also indirectly reflect human effects on
freshwaters. In-lake alkalinity often increases with eutrophi-
cation, while nutrient inputs from agriculture and human
effluents tend to be greatest in landscapes dominated by car-
bonate-rich minerals (Kolada et al., 2014; Alahuhta, 2015).
Similarly, regional spatial extent is often positively associated
with beta diversity, as in our work, because larger areas
incorporate higher levels of environmental heterogeneity
(Gaston, 2000; Anderson et al., 2011; Heino et al., 2015).
Moreover, spatial extent was also positively related to alkalin-
ity range and temperature range, both expressions of envi-
ronmental heterogeneity. These explanations suggest an
underlying effect of environmental heterogeneity on aquatic
macrophyte beta diversity that may also be affected by
human activities that impair water quality and physical char-
acteristics of near-shore habitats (Kosten et al., 2009;
osmarty et al., 2010; Alahuhta, 2015; Vilmi et al., 2017).
Besides discovering novel patterns in macrophyte beta
diversity, our main result has practical implications for envi-
ronmental management: the conservation of aquatic macro-
phyte assemblages that naturally exhibit high species
turnover will be most favoured by a regional approach, in
which multiple lakes that span a wide environmental gradi-
ent are protected within a region (Socolar et al., 2016). This
approach further underlines the need to maximize the total
area protected, independent of the geographical location.
Conversely, low-biodiversity regions characterized by high
nestedness require conservation actions that prioritize high-
diversity sites over those of lower diversity (Socolar et al.,
2016). In these low-biodiversity regions, the possible influ-
ence of land-based activities within a catchment should be
carefully evaluated and connectivity among high-diversity
habitats should be maintained.
We thank Andres Baselga for insightful comments on the
calculation of beta diversity. Comments from Christine Mey-
nard, Solana Boschilia, Chad Larsen and an anonymous
reviewer improved the manuscript considerably. We also
thank Lucinda B. Johnson and Sidinei M. Thomaz for pro-
viding Minnesota and part of the Brazilian data, respectively.
We appreciate assistance from Konsta Happonen in produc-
ing some of the figures. The gathering of the Finnish data
Journal of Biogeography
ª2017 John Wiley & Sons Ltd
Beta diversity of aquatic macrophytes
was partly supported by Biological Monitoring of Finnish
Freshwaters under diffuse loading -project (XPR3304)
financed by Ministry of Agriculture and Forestry and partly
by national surveillance monitoring programs of lakes. S.H.
and M.M. were supported by the EU-funded MARS-project
(7th EU Framework Programme, Contract No.: 603378).
SALGA-team, especially Gissell Lacerot, Nestor Mazzeo, Vera
Huszar, David da Motta Marques and Erik Jeppesen for
organizing and executing the SALGA field sampling cam-
paign and Bruno Irgang
and Eduardo Alonso Paz for help
with identification. Swedish macrophyte data were collected
within the Swedish Monitoring Program of macrophytes in
lakes funded by the Swedish Agency for Marine and Water
Management. S.K. was supported by NWO Veni grant
86312012. Macrophyte data from Brazilian Amazon were col-
lected within a limnological monitoring program funded by
Vale S.A. The vast majority of macrophyte data from Polish
lakes were collected within the State Environmental Monitor-
ing Programme and were provided by the Inspection for
Environmental Protection. Macrophyte data for British lakes
were collated by the Joint Nature Conservation Committee
from surveys resourced by the national conservation agen-
cies. Swiss macrophytes data were collected during a study
financially supported by the Swiss Federal Office for the
Environment. Wisconsin data collection was funded by the
Wisconsin Department of Natural Resources and supported
by the Wisconsin Cooperative Fishery Research Unit. The
Norwegian macrophyte data were collected within the Euro-
pean Union project ‘LAKES Long distance dispersal of
Aquatic Key Species’, contract no. env4-ct-97-0585.
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Additional Supporting Information may be found in the
online version of this article:
Appendix S1 Description of lakes and surveys.
Appendix S2 An example of convex hull.
Appendix S3 Correlation matrix among environmental
Appendix S4 Beta diversity and environmental determinants.
Janne Alahuhta is a postdoctoral researcher in the Univer-
sity of Oulu. His research integrates biogeography, macroecol-
ogy, community ecology and conservation ecology to study
patterns and processes structuring aquatic plants at various
spatial scales. He is especially interested to understand how
global change affects aquatic macrophyte distributions across
temporal and spatial scales. The research group is devoted to
the study of aquatic plants and other freshwater assemblages
from different perspectives at various spatial scales.
Author contributions: J.A. and J.H. conceived the ideas; all
authors participated in the collection of the data; J.A. anal-
ysed the data; and J.A. led the writing to which other authors
Editor: Christine Meynard
APPENDIX 1: Data sources
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and environmental implications of mechanical harvesting of
aquatic vegetation in Southern Chemung Lake. Ministry of
the Environment and Ministry of Natural Resources,
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Journal of Biogeography
ª2017 John Wiley & Sons Ltd
J. Alahuhta et al.
... Local environmental variables consisted of lake area (km 2 ), Secchi depth (m), and water total phosphorus concentration (µg/l). Local variables were surveyed and determined following similar methods within each study region (see Alahuhta et al., 2017, 2018and García-Girón et al., 2020b, 2020c for details). Climate variables included atmos-pheric annual mean temperature (°C), atmospheric annual temperature range (°C), and annual precipitation (mm) defined for each study lake based on 30 years average values (1-km resolution data) obtained from WorldClim (Hijmans et al., 2005). ...
... We applied MRT based on Euclidean distance of χ 2 -transformed multivariate species data (i.e., response variables) and climatic and local environmental variables as explanatory variables. We also ran trial analyses with latitude and longitude included among the predictor variables to Alahuhta et al., 2017, 2018and García-Girón et al., 2020b, 2020c for details). Photographs are courtesy of (from left to right): Laura Sass, Håkan Sansten, Jun Xu, Roger P. Mormul, Sarian Kosten, Mark V. Hoyer, Laila Rhazi, and Jorge García-Girón. ...
... Se indican las regiones estudiadas con triángulos de colores y anexas al mapa algunas fotografías de lagos representativos en (de izquierda a derecha) los Bosques Mixtos de la Provincia Laurentina en Wisconsin (EE. UU.), Noruega, Finlandia, China, la llanura aluvial del Río Paraná, la costa este de Brasil, Florida, Marruecos y España (consultar Alahuhta et al., 2017, 2018y García-Girón et al., 2020b, 2020c account for potential effects of dispersal barriers across regions (Heino & Alahuhta, 2015). Our results, however, remained largely the same when latitude and longitude were forced into the set of constraining variables, and their inclusion did not increase the explanatory power of the MRTs. ...
Full-text available
Unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradients at large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants across continents. Using a dataset of almost 500 observations of lake plant community composition from six continents, we examined, for the first time, if such breakpoints in geographical space exist for freshwater plants and how well a suite of ecological factors (including climatic and local environmental variables) can explain transitions in community composition from the subtropics to the poles. Our combination of multivariate regression tree (MRT) analysis and k-means partitioning suggests that the most abrupt breakpoint exists between temperate to boreal regions on the one hand and freshwater plant communities harbouring mainly subtropical or Mediterranean assemblages on the other. The spatially structured variation in current climatic conditions is the most likely candidate for controlling these latitudinal patterns, although one cannot rule out joint effects of eco-evolutionary constraints in the harsher high-latitude environments and post-glacial migration lags after Pleistocene Ice Ages. Overall, our study supports the foundations of global regionalisation for freshwater plants and anticipates further biogeographical research on freshwater plant communities once datasets have been harmonised for conducting large-scale spatial analyses.
... Environmental heterogeneity is considered a major mechanism generating differences in beta diversity (e.g., Melo et al. 2009), even reversing the latitudinal beta diversity gradient (Alahuhta et al. 2017). The absence of differences in beta diversity in these two sets of ponds, in contrast to the expected higher beta diversity in the tropical ponds, could be explained by no observed major differences in environmental heterogeneity between regions or by the higher limnological heterogeneity in the Mediterranean ponds. ...
The latitudinal diversity gradient predicts that tropical regions should have higher alpha, beta, and gamma diversity than temperate areas. However, only a few studies have assessed the temporal variability of the different components of diversity across climatic regions. In this study, we compare, using a spatial and temporal approach, the diversity of multiple taxa inhabiting tropical and Mediterranean temporary ponds. We sampled the biological communities of each set of ponds on three occasions during the same hydrological year. Under a spatial framework, we analyzed, alpha, beta, and gamma diversities. With a temporal approach, we compared the coefficients of variation in alpha diversity for each local community, and temporal beta diversity. Differences between regions and sampling periods were tested using generalized linear mixed models. We found higher gamma and alpha diversity in the tropical ponds, as expected given the latitudinal differences between them. However, phytoplankton and microinvertebrates from the Mediterranean region, matched or even exceeded tropical alpha diversity on some occasions. Spatial beta diversity did not differ between regions, and it showed lower values at the middle or the end of the hydroperiod in bacteria, micro- and macroinvertebrates and amphibians. Thus, processes homogenizing and heterogenising pond metacommunities must be balanced in both studied regions. Temporal variation in alpha and beta diversity was similar for ponds in both regions, except for macroinvertebrates and amphibians, suggesting differential effects on community variation observable only in animals with longer life-spans, at our temporal scale of analysis.
... Despite their crucial importance in ecosystems aquatic plants are still the least studied in many regions of the world (Chambers et al., 2008;Alahuhta et al., 2017;Murphy et al., 2019), especially in vast and poorly accessible territories, such as North Asia (e.g., Chemeris et al., 2019). Thus, taking into account the ongoing climate changes and increase of human impact, it is timely to assess the diversity, to study the patterns of formation of aquatic flora, to identify evolutionary mechanisms and pathways and to reveal adaptations in the rapidly changing aquatic ecosystems. ...
The species composition and extent of hybridization in Sparganium subgenus Xanthosparganium in North Eurasia reported in different published sources significantly vary. Thus, we aimed to clarify the taxonomy and distribution of aquatic Sparganium in that area. We supplemented the existing fragmentary genetic and morphological data mainly from North America and South Asia with our data from East Europe and North Asia. We combined molecular barcoding of the nuclear phyC and plastid psbJ-petA DNA regions (382 samples) with morphological analysis of herbarium collections (more than 1500 specimens from 16 herbaria) and numerous natural populations with a special focus on hardly accessible Siberian and the Far Eastern regions of Russia. We found that aquatic Sparganium is represented in North Eurasia by nine species and 14 hybrids. Nine previously unknown hybrids are formally described as new nothotaxa. All species and hybrids could be reliably discriminated with barcoding. We refined the distribution of all taxa in North Eurasia, e.g., S. angustifolium, a species avoiding continental areas, where it was confused by many authors with mostly vegetative specimens of other taxa. In the S. emersum complex in addition to recognized earlier widespread S. emersum and eastern North American S. chlorocarpum we proved the existence of one more distinct lineage – Asian Pacific S. rothertii. We discovered different evolutionary lineages within some species (e.g., S. glomeratum and S. hyperboreum) causing additional issues in the taxa identification. Almost all species cross with each other, usually acting both as plastid and pollen donors. Most of the hybrids are widespread and abundant. They originate each time when the ranges of parental species overlap and suitable habitats are available, and rather do not disperse from the centres of origin. Hybridization can be a threat to species with narrow ecological tolerance. Active gene flow is also evident within species when different evolutionary lineages come in contact (e.g., S. emersum, S. rothertii, S. glomeratum, S. hyperboreum, S. natans). We provide a new taxonomic treatment, which solves many long-standing issues in subgenus Xanthosparganium, and a new identification key for both species and hybrids occurring in North Eurasia. Full-text available on request.
... The sufficient natural resources and diverse habitats in these areas provide the basis for the survival and diversification of insects Liu et al., 2022b). In addition to the insects studied herein, habitat heterogeneity has also been shown to influence patterns of beta diversity across a broad range of taxa, such as plants (Alahuhta et al., 2017;He et al., 2020), amphibians (Baselga et al., 2012), birds (Veech and Crist, 2007), and mammals (Arita, 1997;Wen et al., 2016). A higher level of habitat heterogeneity provides more diverse niches for species survival, thereby favoring the formation of species diversity through a niche filtering effect (Baselga et al., 2012). ...
Understanding large-scale biodiversity patterns and underlying mechanisms during the formation process is essential for guiding conservation efforts. However, previous studies on the identification and formation mechanism of diversity hotspots in China were often limited to a single (alpha) diversity metric, while multiple (beta or zeta) diversity has rarely been used for exploring drivers and conservation actions. Here, a comprehensive species distribution dataset consisting of representative families of three insect orders was compiled to explore biodiversity hotspots based on different algorithms. Furthermore, to assess the effects of environmental factors on hotspots, we fitted generalized additive mixed-effects models (GAMMs) for species richness, generalized dissimilarity models (GDMs) and multi-site generalized dissimilarity modeling (MS-GDM) for the total beta and zeta diversity. Our results showed that biodiversity hotspots were mainly concentrated in central and southern China, especially in mountainous areas with complex topography, which indicated the insects' affinity to montane environments. Further analyses based on multiple models showed that water-energy factors exerted the strongest explanatory power for the insect assemblage diversity in hotspots of both alpha and beta (or zeta) levels. Additionally, anthropogenic factors also exerted a significant effect on hotspots, and this effect was higher for beta diversity than for alpha diversity. Overall, our study elucidates a comprehensive analysis of the identification and underlying mechanism of biodiversity hotspots in China. Despite several limitations, we still believe that our findings can provide some new insights for conservation efforts in Chinese hotspots.
... There is a high chance of having similar tree species when two or more forest areas are close, due to the migration of genetic traits dispersed by wind and birds. This finding is in line with the reports of Alahuhta et al. (2017) and Astorga et al. (2014), who reported that heterogeneity in distant locations influences beta diversity by providing a greater variety of niches or species. Species diversity in term of similarity or dissimilarity indicates the geographical variation of species composition among habitats ; and is importantly related to two processes (Baselga 2010): species replacement and nestedness . ...
Full-text available
To understand the health conditions and growth patterns of forest estates for environmental resilience and climate change mitigation, assessment of structure and species diversity is paramount. This study aimed at assessing the structure, alpha, and beta diversities of tree species in three ecological zones in Taraba, Nigeria, for management purposes. In recent times, no research has been reported on the structure and beta diversity of the study areas. A systematic sampling design was used for data collection. Five sample plots of 50 x 50 m were laid in each of the six natural forest areas. The result showed a mean DBH of 42.5 cm and a tree height of 15.0 m in the forests. The forests have a structure of an inverse "J-shape," which is typical of natural forests in the tropics. The southern Guinea savanna zone had the highest mean Shannon-Weiner diversity index (2.8). The least beta diversity index (0.02) was between Baissa and Jen Gininya forest areas. Baissa and Bakin Dutse Protected Forest Areas (PFAs) contained 76.5% of the tree species. There is a high chance that all tree species will be found in these 2 forest areas. Proximity to a location influences how similar two tree species are, according to the least beta diversity index (0.02) recorded. The Federal Government's method of management for the forest, known as Gashaka Gumti National Park, may be responsible for the high beta diversity index in the Montane ecozone. Therefore, it should be strongly encouraged to practice strict oversight of natural areas, as their contributions to reducing climate change in Taraba State, Nigeria, cannot be overstated.
... Although the impact of macrophytes has been studied for many years, the influence of water levels on the development of the littoral zone still is not well understood. Mostly, this zone is dominated by emergent macrophytes characterized by high productivity [28,29], which are relatively resistant to water level changes [30]. Moreover, the reduction of water levels may lead to faster succession of macrophytes to open water, causing lake overgrowing or succession of terrestrial species [31,32]. ...
Full-text available
Decreased water levels due to climate change cause many negative effects on lake ecosystems. The aim of this study was to (a) assess the effect of the reduction of water levels on nutrient availability in the sediment in the littoral zone; (b) evaluate the effect of changes in water level on biomass productivity and nutrient concentrations in the aboveground biomass of four emergent species: Phragmites australis (Cav.) Trin. ex Steud., Typha angustifolia L., Carex acutiformis L., Glyceria maxima (C. Hartm.) Holmb; and (c) assess the efficiency of the littoral zone in the reduction of nutrient pollution. The study hypothesis was that water level reduction has a positive effect on the plant biomass of high productive species. The study was carried out in the littoral zone of Tomickie Lake, situated in the western part of Poland. This lake is located in the protected area—the buffer zone of Wielkopolska National Park, and at the international level—Natura 2000. Six transects, perpendicular to the shoreline, were selected at two subzones—permanently and seasonally flooded. Analyses of nutrient concentrations in sediments and plant species were performed. The results show the higher productivity of reeds in the zone where water occurs seasonally at the site through the year, which reached 1193 g dry weight/m2. The decline of the water level may lead to the increased growth of highly productive species as emergent vegetation with a broad ecological scale in terms of nutrient concentrations and changes of water depth, i.e., Phragmites australis (Cav.) Trin. ex Steud. Species that prefer growth in the deeper part of the lake will be characterized by lower productivity, despite the high availability of nutrients. Changes in the availability of nutrients may cause the intensification of lake overgrowth by very productive species, which may affect biodiversity, which is particularly high in protected areas.
... Because a better understanding of diversity patterns is critical for managing and preserving aquatic ecosystems (Alahuhta et al., 2017), it is critical to understand beta diversity pattern and its components to manage freshwater ecosystems (Fernández-Aláez et al., 2020). Conservation biologists must strategically prioritise conservation efforts when resources are limited to maximise benefits (Dubois et al., 2020). ...
A modern approach to understanding biodiversity variation is to deconstruct beta diversity patterns into the local contribution to beta diversity (LCBD-uniqueness in species composition of a site) and species contribution to beta diversity (SCBD-influence of a species in the beta diversity within the region) which is a good approach to improving knowledge of the beta diversity. We carried out this work to understand the pattern and relationship of LCBD, SCBD and the rarity of the spider community in the riparian habitat of the Ganga River. We calculated the correlation between LCBD and species richness of both all the species and rare species. We used the first order and second order terms to find the relationship between SCBD and the number of sites occupied by species and to find the relationship between SCBD and the index of rarity for all the species and three ecological guilds of spiders. We found that the LCBD of the spider community had a significant relationship with total species richness but not with rare species richness. Spider species with intermediate occurrence across the study sites contributed more to SCBD values than species with high and low occurrence. We found that the index of rarity of spider species had a significant relationship with SCBD values. The non-parametric permutational multivariate analysis of variance (PERMANOVA) tests revealed no significant differences in the distribution of different ecological guilds of spiders between the study sites. The integrated LCBD and SCBD approach can be used to carry out effective conservation and restoration programmes that preserve the structural, functional, and ecological diversity of spiders, as well as other biological communities in riparian ecosystems.
... Heino et al. (2009) showed that macrophyte β-diversity was higher in preserved streams compared to the ones impacted by forestry. Johnson and Angeler (2014) found high macrophytes β-diversity along agricultural landscapes (impacted sites), implying that the diversity of resistant taxa is high, while there is a loss of sensitive taxa due to disturbance, whereas a global variation in macrophytes β-diversity in lakes was driven by environmental heterogeneity (Alahuhta et al. 2017). ...
Full-text available
Land use has transformed landscapes, altered water and soil physical–chemical parameters, reduced habitat availability, and limited species occurrence. Here, we investigated the contribution of sites (local contribution to beta diversity—LCBD) and species (species contribution to beta diversity—SCBD) to macrophyte total β-diversity in streams inserted in a gradient of land use. We also investigated which life forms are important to SCBD and which environmental parameters are related to the change in the species composition. Sampling took place in 17 streams located in Paragominas, Pará, Brazil in September 2017. We recorded 36 species and four life forms. We identified five sites with high LCBD. The species with the four highest SCBD scores belong to the amphibious life form. CDI (Catchment Disturbance Index) and canopy cover, variables that show land use degrees, drove the distribution of macrophyte species in the land use gradient. CDI presented a positive relationship with LCBD, whereas canopy cover presented a negative relationship, i.e., a greater composition of unique species and greater diversity of macrophytes life forms were found in more altered streams than in preserved ones, due to canopy openness. Nonetheless, we emphasize that although the environmental characteristics of altered streams favored the establishment of more macrophytes species, the species found could be generalists and the pattern for other types of environments is usually the opposite. Therefore, studies focusing on temporal patterns will be important for this area to understand how the macrophyte community will stabilize. This study brings important contributions to elucidate the effects of land use on macrophytes distribution and the role played by different life forms.
... Along the elevational gradient, all factors contributing to the increase in the diversity of vascular macrophyte vegetation are decreasing. Several studies have shown an opposite pattern, suggesting that the observed response of macrophyte communities to altitude might depend on the analyzed range of the elevational gradient [52,53,56,57]. ...
Full-text available
There is a gap in the knowledge about how environmental factors affect functional diversity and trait structures of macrophyte communities in altered waterbodies. We used macrophyte and environmental data collected from 46 waterbodies; we extracted data on 14 traits with 43 attributes for 59 species and calculated seven functional diversity indices. We used redundancy analysis (RDA) to investigate the response of functional diversity indices to the environmental variables. To relate traits to environment we performed the analysis on three data matrices: site by environmental variables (R), site by species (L), and species by traits (Q)-the RLQ analysis, and the 4th corner analyses. The RDA showed that the environmental variables explained 47.43% of the variability in the functional diversity indices. Elevation, hemeroby (integrative measure of the impact of all human intervention) of the land cover classes on the banks, and water conductivity were correlated with all diversity indices. We found that the traits characteristic of floating and emergent plants represents a strategy to increase efficiency in light interception under high nutrient concentrations in lowland waterbodies, while submerged plants dominate nutrient-poorer waterbodies at higher altitudes. Future investigations should be focused on the role of functional diversity and the structure of macrophyte communities in the indication of tradeoffs and/or facilitation between ecosystem services that altered waterbodies provide, in order to guide their adequate management.
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The Amazon forests are under threat from multiple human land uses, but the effect of the different types of land uses on environmental heterogeneity and the α- and β-diversity of aquatic insects remains unclear. We studied how habitat features of streams and aquatic insect diversity in the orders Ephemeroptera, Plecoptera, and Trichoptera (hereafter, EPT) responded to different land uses in the Brazilian Amazon. By sampling and analyzing EPT community data from 83 streams distributed in multiple land uses and land covers, we found that the impact of forest conversion was mixed. Despite contiguous and fragmented forest streams presenting similar environmental conditions, they differed in insect diversity metrics. α-diversity was highest in contiguous forest streams and EPT β-diversity was higher in streams surrounded by livestock farming and primary oil palm plantations. The association between land use and habitat degradation may not be so direct, mainly when streams are inserted into or surrounded by forest fragments. This has important implications because politicians and policymakers often regard forest fragments as degraded landscapes, to justify their conversion to other land uses. Our study shows that forest fragments must be protected and restored to reduce the risks of degrading the ecological condition of Amazonian streams.
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One of the most intriguing questions in current ecology is the extent to which the ecological niches of species are conserved in space and time. Niche conservatism has mostly been studied using coarse-scale data of species’ distributions, although it is at the local habitat scales where species’ responses to ecological variables primarily take place. We investigated the extent to which niches of aquatic macrophytes are conserved among four study regions (i.e. Finland, Sweden and the US states of Minnesota and Wisconsin) on two continents (i.e. Europe and North America) using data for 11 species common to all the four study areas. We studied how ecological variables (i.e. local, climate and spatial variables) explain variation in the distributions of these common species in the four areas using species distribution modelling. In addition, we examined whether species’ niche parameters vary among the study regions. Our results revealed large variation in both species’ responses to the studied ecological variables and in species’ niche parameters among the areas. We found little evidence for niche conservatism in aquatic macrophytes, though local environmental conditions among the studied areas were largely similar. This suggests that niche shifts, rather than different environmental conditions, were responsible for variable responses of aquatic macrophytes to local ecological variables. Local habitat niches of aquatic macrophytes are mainly driven by variations in local environmental conditions, whereas their climate niches are more or less conserved among regions. This highlights the need to study niche conservatism using local-scale data to better understand whether species’ niches are conserved, because different niches (e.g. local versus climate) operating at various scales may show different degrees of conservatism. The extent to which species’ niches are truly conserved has wide practical implications, including for instance, predicting changes in species’ distributions in response to global change.
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Different components of global change (e.g. climate change, land use, pollution and introduced species) continue to alter biodiversity worldwide. As northern regions are still relatively undisturbed and will likely face clear increases in temperature in the near-future, we examined the signs of biodiversity change due to anthropogenic stressors using a systematic review of previous studies. Our aim was to map where, in which way and due to which stressor biodiversity in northern regions has changed. We made a systematic literature search covering the years between 2000 and 2015 to obtain a comprehensive selection of recent research. As species richness was clearly the most commonly used indicator of biodiversity, we only concentrated on this aspect of biodiversity. We compared different biological groups, regions and ecosystems. In the majority of the cases, anthropogenic stressors had decreased species richness, or had no effects on it, while increasing or multiple effects of stressors on species richness were less common. Freshwater ecosystems were most sensitive to anthropogenic stressors, as species richness often decreased due to these stressors. The effects of land use on richness were covered relatively widely in the selected set of articles, but the effects of other components of global change on species richness require further attention. Despite the fact that pollution was not as commonly studied stressor as land use, it was the most harmful stressor type affecting species richness. Geographically, most studies were located in boreal Canada or Fennoscandia, while no studies were executed in vast circumpolar areas where the temperature rise has been greatest and the projected climate change is likely to be fast. Overall, we could find an alarmingly small set of studies that described the effects of actual anthropogenic stressors in real-life circumstances in northern high latitudes.
To design robust protected area networks, accurately measure species losses, or understand the processes that maintain species diversity, conservation science must consider the organization of biodiversity in space. Central is beta-diversity—the component of regional diversity that accumulates from compositional differences between local species assemblages. We review how beta-diversity is impacted by human activities, including farming, selective-logging, urbanisation, species invasions, overhunting, and climate change. Beta-diversity increases, decreases or remains unchanged by these impacts, depending on the balance of processes that cause species composition to become more different (biotic heterogenization) or more similar (biotic homogenization) between sites. While maintaining high beta-diversity is not always a desirable conservation outcome, understanding beta-diversity is essential for protecting regional diversity and can directly assist conservation planning.
One of the fundamental tools in biogeography is the classification of the Earth surface into spatially coherent units based on assemblage distinctiveness. However, spatial coherence of biogeographical regions may be scale-dependent, that is, it may change with changing the size of spatial units used. We ask (1) how the clusters resulting from the classification of animal assemblages at different spatial scales differ in their spatial coherence, (2) whether there are geographical trends in the patterns of spatial coherence, and (3) what factors drive these patterns at different scales and in different areas of Europe.
Tools for performing model selection and model averaging. Automated model selection through subsetting the maximum model, with optional constraints for model inclusion. Model parameter and prediction averaging based on model weights derived from information criteria (AICc and alike) or custom model weighting schemes. [Please do not request the full text - it is an R package. The up-to-date manual is available from CRAN].