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Abellán and Ribera BMC Evolutionary Biology 2011, 11:344
http://www.biomedcentral.com/1471-2148/11/344

RESEARCH ARTICLE

Open Access

Geographic location and phylogeny are the main
determinants of the size of the geographical
range in aquatic beetles
Pedro Abellán1,2* and Ignacio Ribera1

Abstract
Background: Why some species are widespread while others are very restricted geographically is one of the most
basic questions in biology, although it remains largely unanswered. This is particularly the case for groups of
closely related species, which often display large differences in the size of the geographical range despite sharing
many other factors due to their common phylogenetic inheritance. We used ten lineages of aquatic Coleoptera
from the western Palearctic to test in a comparative framework a broad set of possible determinants of range size:
species’ age, differences in ecological tolerance, dispersal ability and geographic location.
Results: When all factors were combined in multiple regression models between 60-98% of the variance was
explained by geographic location and phylogenetic signal. Maximum latitudinal and longitudinal limits were
positively correlated with range size, with species at the most northern latitudes and eastern longitudes displaying
the largest ranges. In lineages with lotic and lentic species, the lentic (better dispersers) display larger distributional
ranges than the lotic species (worse dispersers). The size of the geographical range was also positively correlated
with the extent of the biomes in which the species is found, but we did not find evidence of a clear relationship
between range size and age of the species.
Conclusions: Our findings show that range size of a species is shaped by an interplay of geographic and
ecological factors, with a phylogenetic component affecting both of them. The understanding of the factors that
determine the size and geographical location of the distributional range of species is fundamental to the study of
the origin and assemblage of the current biota. Our results show that for this purpose the most relevant data may
be the phylogenetic history of the species and its geographical location.

Background
Why some species are widespread while others are very
restricted geographically is one of the most basic questions in biology, although it remains basically unanswered, despite the sustained interest from ecologists,
biogeographers and evolutionary biologists (e.g., [1-5]).
A range of ecological and evolutionary explanations
have been suggested for the observed range size variation, based on differences in niche breadth or environmental tolerance, body size, population abundance,
latitude, environmental variability, colonization and
extinction dynamics, and dispersal ability [3,6-8].
* Correspondence: pabellan@um.es
1
Institute of Evolutionary Biology (CSIC-UPF), Passeig Maritim de la
Barceloneta 37, 08003 Barcelona, Spain
Full list of author information is available at the end of the article

However, there are still fundamental questions unresolved, best exemplified by the fact that closely related
species often display dramatic differences in range size
for largely unknown reasons. Tests of these differences
remain relatively scarce, have been performed for examples of very few taxa (usually vertebrates), and generally
fail to address the potentially confounding effects of the
phylogenetic relatedness of species.
In this work we aim to test some likely determinants
of the size of the geographical range in a phylogenetic
comparative framework. Closely related species are
expected to show more similarity than those that are
distantly related because they share more common evolutionary history [9,10]. How range size evolves and the
extent of heritability of the geographical range sizes of
species has received much attention in the last years

© 2011 Abellán and Ribera; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.

Abellán and Ribera BMC Evolutionary Biology 2011, 11:344
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[11-14], as evidence for range size heritability would
have important implications for ecology, evolution, and
biogeography [15]. Although a number of studies have
investigated the existence of phylogenetic signal in range
size in a variety of clades and from a wide range of analytical approaches, the patterns found have been mixed
and the “heritability” of range size remains a contentious
issue [13,14]. Phylogenetic comparative methods applied
to whole lineages and not only species-pairs (e.g.,
[16-18]) may provide a more robust and powerful
approach to estimate the phylogenetic signal in range
size.
Among the potential determinants of range size we
include ecological tolerance, dispersal ability, geographic
location, and age of the species. For all of them we test
their phylogenetic signal, as well as the phylogenetic signal of the size and location of the range itself.
1) Ecological tolerance. A broad ecological niche
allows a species to persist in a wide range of different
environments, while a narrow niche restricts a species
to the few places where its niche requirements are met
[19,20]. Hence, species with broad niches should be distributed over a wider range of different biomes than
species with narrower ecological requirements, leading
to larger geographical ranges [21]. When these biomes
are distributed equally along environmental gradients
this poses the problem that species with lager ranges
will inevitably overlap more different biomes. However,
in the western Palaearctic (the centre of distribution of
most of our studied lineages, see below) this problem is
partly alleviated by the very heterogeneous distribution
of environmental gradients. In this case, those species
occurring in large biomes (e.g., [20,21]) would have
large range sizes (as found e.g. by [14]), but they should
not necessarily occupy more biomes than species with
smaller ranges.
2) Dispersal ability. As a surrogate measure of dispersal ability we use water flow, as previous studies in
freshwater invertebrates have established the relationship between main habitat type (lotic or lentic) and the
size of the geographical range [22,23]. Lentic species
should have better dispersal abilities due to the shorter
geological duration of their habitats, and display on
average larger geographical ranges than the species inhabiting the more persistent lotic habitats [24]. However,
the role of habitat constraints in aquatic organisms has
yet not been assessed from a phylogenetic comparative
framework in lineages in which there are species inhabiting both habitat types.
3) Geographic location. There are multiple cases of
closely related species with a similar biology and ecology
with extreme differences in the size of the geographical
range. In these cases, the biogeographic settings in
which species arise and evolve could determine their

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range sizes [14,25], with species with a “privileged” geographical position displaying higher range-sizes. For
example, latitudinal gradients in geographic range size
(Rapoport’s rule) have been extensively studied and
documented [6,26,27]. Evidence supporting that range
sizes increase with latitude in the Palearctic and Nearctic above 40°-50°N has been found in a number of terrestrial groups [26], but the extent to which this is a
general pattern remains contentious and has rarely been
tested in a phylogenetic framework.
4) Age and area. We also consider the possible relationship between age and area, which requires to be
tested in the context of a phylogeny even if not in the
same comparative framework as the previous factors.
Originally proposed to explain the distribution of the
endemic flora of some islands [28], in its basic form the
“age and area” hypothesis states that the older a species
is the more likely it is to have occupied a wider geographical area. More precisely, it could be expected that
species have a “life cycle” from origin to extinction that
could be described through a variety of simple models
(see [26] for a review). Although a number of studies
have examined the evidence for geographic range size
changes over evolutionary time across a wide range of
clades (but never in insects), no consistent evidence has
emerged to support any particular model [29]. An inherent limitation of all these studies is that a direct test of
the age and area model requires the geographic range
size of a species or a clade to be known throughout its
evolutionary history [3]. This is usually not possible
without extensive palaeontological data. Hence, a different approach has to be taken in neontological studies,
considering interspecific variation in range sizes of contemporary species as a reflection of the intraspecific
relationship [30]. The examination of the interspecies
relationship between geographic range size and age
could thus be used as a surrogate of the transformation
of range size with age in individual species [29,31].
We use a set of lineages of closely related species of
different families of aquatic Coleoptera to investigate the
relative role of different factors on determining the size
of the geographical range of species. The Western
Palearctic water beetle fauna is a suitable model to
study range size issues, as water beetles are a rich and
well-known insect group in both Europe and the Mediterranean Basin, exhibiting a high level of endemism but
also with species widely distributed across the Palearctic
and Holartic regions [32-34]. Spatial determinants of
range size and temporal patterns of range evolution in
invertebrates may differ substantially from that found in
previous studies using vertebrate clades. Hence, the use
of phylogenies at the species level for different groups of
beetles, one of the most diverse and understudied
lineages of animals, in what is in fact a set of

Abellán and Ribera BMC Evolutionary Biology 2011, 11:344
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independent evolutionary replicates, provides a unique
opportunity to assess these issues from a phylogenetic
comparative framework.

4) The Hydroporus planus group (genus Hydroporus)
includes 51 species with a Palearctic distribution [36,40],
also with both lotic and lentic species. We sampled 30
species, including most of the western Palearctic fauna.

Methods

Family Hydraenidae

Background on the studied groups

5) The subgenus Enicocerus (genus Ochthebius) includes
15 recognized species exclusive of running waters [41],
distributed in Europe and the middle East. We studied 9
species, including all member of the O. exculptus group
[41].
6) The genus Limnebius Leach, with an almost worldwide distribution [42], is one of the most diverse genera
of the family Hydraenidae. In his revision of the Palearctic species, Jäch [42] recognized several species groups,
based on both external morphology and the structure of
the male genitalia. Among them, the Limnebius nitidus
subgroup includes 11 western Palearctic species with a
rather uniform external morphology [43]. Several species
of this lineage have very restricted allopatric distributions, often limited to a single valley or mountain system, but there are also some species with wider
geographical ranges. All inhabit running waters. We
included all the species within this subgroup with a sole
exception (L. nitifarus).
7-8) The “Haenydra“ lineage (genus Hydraena) currently includes 86 recognized species [44,45] usually
found in clean, fast flowing waters, often in mountain
streams. They are distributed in the north Mediterranean region from Iberia to Iran. Many species of this
lineage have very restricted distributions, often limited
to a single valley or mountain system, but there are also
some species with very wide geographical ranges, such
as e.g., H. gracilis, present in the whole Europe from
north Iberia to the Urals [45]. Here, we included two
different monophyletic lineages within “Haenydra“: the
H. gracilis and the H. dentipes clades [46], with 27 and
28 species respectively, of which we include 14 and 20.
9) The “Phothydraena” lineage (genus Hydraena [47])
currently include 9 recognized species, usually found in
clean, fast flowing waters, often in mountain streams.
Molecular data were available for seven species.

We have used a phylogenetically heterogeneous set of
ten monophyletic lineages of water beetles (Table 1)
occurring in the western Palearctic, some with both
lotic and lentic species, and others encompassing exclusively either lotic or lentic species. The lineages used
here belong to three different families of two suborders
of Coleoptera (Adephaga and Polyphaga), representing
several independent invasions of the aquatic medium
[35]. The full list of species and data used in this study
are provided in Additional file 1.
Family Dytiscidae

1) The Ilybius subaeneus group (genus Ilybius [36])
includes 33 recognized species, occurring almost exclusively in stagnant water and with generally wide geographical ranges throughout large parts of the Palearctic or
Nearctic, with some Holarctic species [36,37]. Together
with the genus Rhantus, they are the most species-rich
clade of the Palearctic fauna confined to stagnant water.
Our dataset included 27 species.
2) The genus Deronectes is the largest clade of
Palearctic Dytiscidae entirely confined to running
waters, with a predominantly Mediterranean distribution
reaching central Asia in the east [36]. Species are usually
restricted to relatively small geographical ranges, frequently in mountain regions. Here, we focused on the
western Mediterranean clade, encompassing 26 recognized species or subspecies [38] of which our final dataset included 24.
3) The genus Graptodytes includes 21 recognized species distributed in the western Palearctic region [39],
with both lotic and lentic species. Our final dataset
included 18 taxa.
Table 1 Lineages of water beetles studied
Lineage

Taxa

Habitat

Ilybius subaeneus group (Dytiscidae)

27 (33)

Lentic

Western Mediterranean Deronectes (Dytiscidae)

24 (29)

Lotic

Subgenus Enicocerus (Hydraenidae)
Limnebius nitidus subgroup (Hydraenidae)

9 (14)
10 (10)

Lotic
Lotic

Hydraena gracilis lineage (Hydraenidae)

14 (27)

Lotic

Hydraena dentipes lineage (Hydraenidae)

20 (28)

Lotic

9 (9)

Lotic
Mixed

“Phothydraena” lineage (Hydraenidae)
Palaearctic Graptodytes (Dytiscidae)

18 (23)

Hydroporus planus group s.l. (Dytiscidae)

30 (52)

Mixed

West Palaearctic Hydrochus (Hydrochidae)

13 (14)

Mixed

Lineages of water beetles included in this study. The number of species
included (in parenthesis the total number of species in the lineage) and the
habitat preference are indicated.

Family Hydrochidae

10) The genus Hydrochus includes about 180 described
species [48]. In the west Mediterranean (Iberian Peninsula, Morocco and south France) the genus is represented by 12 recognized species, 7 of them endemic to
the area, which form a monophyletic group that also
includes H. roberti, so far recorded from the Caucasus
and Turkey [49]. We include 12 of the 13 species of this
clade.
Phylogenetic data

We reconstructed the phylogenetic relationships within
each lineage of water beetles from different

Abellán and Ribera BMC Evolutionary Biology 2011, 11:344
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combinations of mitochondrial and nuclear genes,
depending on data availability. Phylogenies of Graptodytes, Enicocerus, “Haenydra“ and Hydrochus were taken
from recent works ([39,41,46,49]) respectively), pruning
the trees to keep one specimen per species. Phylogenies
of Deronectes, Ilybius and Hydroporus were updated
with additional species and new analyses from [38] and
[40] respectively; finally, phylogenies of Limnebius and
Phothydraena were newly built for this work, with the
same genes and methodology used in [46] for the two
lineages of “Haenydra“ (see Additional file 1 for details
of the sequence data used for each lineage, Additional
file 2, Table S1 for the primers used for amplification
and sequencing, and Additional file 3 for the final trees
used).
New phylogenies were built using a fast maximum
likelihood algorithm as implemented in RAxML v7.0
[50], after aligning length-variable regions with MAFFT
v5.8 [51]. For the RAxML searches we used a partition
by gene fragment, with a GTR+G evolutionary model
independently estimated for each partition, following the
methodology used in [46]. To estimate the relative age
of divergence of the lineages we used the Bayesian
relaxed phylogenetic approach implemented in BEAST
v1.4.7 [52], which allows variation in substitution rates
among branches. We implemented a GTR+I+G model
of DNA substitution with four rate categories using the
mitochondrial data set, as the a priori rate used was
estimated for mitochondrial genes only (see below). We
used an uncorrelated lognormal relaxed molecular clock
model to estimate substitution rates and the Yule process of speciation as the tree prior. Well supported
nodes in the analyses of the combined sequence (when
nuclear genes were used) were constrained to ensure
that the Beast analyses obtained the same topology. We
ran two independent analyses for each group sampling
each 1000 generations, and used TRACER version 1.4 to
determine convergence, measure the effective sample
size of each parameter and calculate the mean and 95%
highest posterior density interval for divergence times.
Results of the two runs were combined with LogCombiner v1.4.7 and the consensus tree compiled with
TreeAnnotator v1.4.7 [52]. As each lineage was analysed
separately, to establish the relationship between age and
size of the geographical range we only require a relative
dating of species within the lineage, not an absolute dating. Notwithstanding this, we used an approximate dating using as prior evolutionary rate for the combined
mitochondrial sequence (including protein coding and
ribosomal genes) a normal distribution with average rate
of 0.01 substitutions/site/MY, with a standard deviation
of 0.001. This rate is close to recent estimations of different groups of Coleoptera [46,53] and to the standard
arthropod mitochondrial clock of 2.3% [54,55].

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The evolutionary age of each species was calculated as
the estimated age (in millions of years) of the most
recent node that connects it to any other taxon or
clade. The age estimates of Beast have usually large 95%
confidence intervals, which has to be considered in the
interpretation of the Results.
Geographical data and biogeographic factors

We created shaded maps of the distribution of the different species in a Geographic Information System
based on the information compiled from published and
unpublished sources [36,37,44,48,56,57]; checklist of the
species of the Italian fauna, v. 2.0, http://www.faunaitalia.it). This resulted in individual species maps containing one or more polygons of distribution (species maps
are available from the authors upon request). We then
calculated different descriptors of the species’ ranges:
total range-size, maximum latitudinal and longitudinal
limits, and latitudinal and longitudinal centroids.
Total range-size was calculated as the total area of the
polygon or polygons, after reprojecting species maps to
equal-area projections. For those species only known
from their locality type (four species), range size was
arbitrarily set to 100 km2. Latitudinal and longitudinal
centroid positions (centre of mass of the polygon or
polygons) and maximum latitudinal and longitudinal
limits were computed as geographical coordinates.
All spatial data were processed using ArcGIS 9.2 software (Environmental Systems Research Institute Inc.,
Redlands, CA). Area variables (total range-size and average size of biomes) were log10 transformed for the
analyses.
Ecological factors

The main habitat type of the studied species was defined
according to the general water flow regime, and three
categories were distinguished: (1) lotic (strictly running
water); (2) both running and standing water; and (3)
lentic (strictly standing water) (see [22] for details on
habitat choice criteria) (Additional file 1). For some analyses we pooled species in categories (2) and (3), thus
dividing species limited to running water from the rest.
Water flow is the most important habitat characteristic
determining the composition of the assemblages of
aquatic Coleoptera, and species tend to be restricted to
either standing water bodies or to running water, both
in the larval and in the more dispersive adult stage (see
[22,24] and references therein).
To determine the role of niche breadth on range-size
we used the number of different biomes that partly or
completely overlap with the species ranges based on the
biomes delineated by the World Wildlife Fund (http://
www.worldwildlife.org/science/ecoregions/item1847.
html). We discarded biomes that overlapped less than

Abellán and Ribera BMC Evolutionary Biology 2011, 11:344
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1% of the species’ range, to minimize the effects of
uncertainty in range size calculations. To try to disentangle the effect of the range size per se from that of an
increased ecological tolerance, we tested whether species
that are found in larger biomes have larger ranges than
species in smaller biogeographic units. If so, this would
suggest that range size is a function of the available biogeographic space, rather than the number of biomes
being a function of the size of the range. For that purpose we calculated the mean size of the biomes that
partly or completely overlap with the species ranges
[25].
Data analyses
Phylogenetic signal

We used a randomization procedure to test whether range
attributes exhibit a significant tendency for related species
to resemble each other according to the methodology proposed by Blomberg et al. [17]. The basic idea is to ask
whether a given tree (topology and branch lengths) better
fits a set of tip data as compared with the fit obtained
when the data have been randomly permuted across the
tips of the tree, thus destroying any phylogenetic signal
that may have existed [17]. Thus, the degree of resemblance among relatives can be distinguished from random
by comparing observed patterns of the variance of independent contrasts of the trait to a null model of shuffling
taxa labels across the tips of the phylogeny.
To quantify the amount of phylogenetic signal we calculated the metric K, which compares the observed signal in a trait to the signal under a Brownian motion
model of trait evolution on a phylogeny [17]. The higher
the K statistic, the more phylogenetic signal in a trait. K
values of 1 correspond to a Brownian motion process,
which implies some degree of phylogenetic signal. K
values closer to zero correspond to a random or convergent pattern of evolution, while K values greater than 1
indicate strong phylogenetic signal. We used the R package ‘Picante’ [58] to compute K and the significance test.
We also used phylogenetic eigenvector regression
(PVR; [59]) as an additional assessment of the phylogenetic signal in range properties and to correct for this
signal in analysing the relationship between range-size
and biogeographical variables (see below). The basic
idea of PVR is to carry out a principal coordinate analysis of the matrix of pairwise phylogenetic distances
between species and use the eigenvectors as predictors
in a multiple regression against species traits (in this
case, geographic range properties). The subset of eigenvectors to use as PVR components for each range attribute was obtained using a stepwise multiple regression
[60]. The R 2 of the multiple regression model of the
trait against the eigenvectors provides an estimate of the
amount of phylogenetic signal in the data [59].

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To assess if habitat occupation exhibited phylogenetic
signal, habitat type was used as a qualitative (discretelycoded) character, and species were assigned to either of
the three habitat type classes: lotic, lentic or both. In
this case, phylogenetic signal was computed with Pagel’s
l [16,18], a more appropriate approach for discrete
traits. The value of l varies from 0 to 1, where 0 corresponds with the complete absence of phylogenetic structure and 1 means that variation in the trait is perfectly
correlated with phylogeny. We used the fitDiscrete function of the R package ‘Geiger’ [61] to obtain the maximum likelihood estimate of l. In order to address
whether significant phylogenetic signal existed in our
datasets, we compared the negative log likelihood when
there was no signal (i.e. using the tree transformed
lambda = 0) to that when lambda was estimated using
the original tree topology by using a likelihood ratio test.
PGLS correlations

We explored the association between range size and different biogeographical and ecological factors in a phylogenetic framework. We used the Phylogenetic
Generalized Least Squares approach (PGLS; [62]) as
implemented in Compare 4.6 b, which allows tests for
correlations between two continuous traits and between
a discrete independent variable and a continuous dependent variable [63]. PGLS can be viewed as an extension
of Felsenstein’s independent contrasts method [64] that
allows for flexibility in the underlying evolutionary
assumptions. This flexibility is obtained through the use
of a single parameter (alpha), which can be interpreted
as a measure of evolutionary constraint acting on the
phenotypes. When alpha is small, generalized least
squares approximates Felsenstein’s independent contrasts analysis, and when alpha is large, comparative
data are less dependent on phylogeny and approximate
a raw, nonphylogenetic correlation analysis. The Compare software computes the maximum likelihood estimate of alpha (from a range of different alphas), and
provides parameter estimates given that maximum likelihood. To assess the significance of the relationship
between traits we tested if the regression slope differed
from zero. Since the correlation coefficient is directly
related to the regression slope, if this differs significantly
from zero, the correlation coefficient will too. For this,
we used the corMartins function of the R package ‘Ape’
[65] with the estimated value of alpha to create the correlation structure, and then fitted the linear model with
the gls function.
Range-size vs. Age

In order to examine the relationship between geographic
range size and species age, plots of range size (log10
transformed) against species age (i.e. the estimated age
of divergence between species) were produced for each
group [29,31]. Statistical significance was determined

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using linear or quadratic regressions as appropriate
according to an extra sum-of-squares F test.
Global determinants of range size

A multiple regression analysis was used to determine
the relative importance of the different variables, regressing the log-transformed range-size (response variable)
upon the explanatory variables (range properties, species’ age, niche breadth and habitat preference) and the
phylogenetic PVR components. Habitat type was coded
as a dummy variable (0, strictly lotic species; 1, species
inhabiting lentic waters or both lentic and lotic waters).
Preliminary analyses showed that some subsets of the
geographic properties of the range were often correlated.
This was also corroborated by visual examination
through Principal Component Analysis. Similarly, the
average size of biomes and the number of biomes were
usually highly correlated with maximum latitude or
longitude. As a consequence, high levels of multicollinearity were detected, as indicated by high values of the
Variance Inflation Factor [66]. To avoid this multicollinearity, only maximum latitude and longitude (the main
determinants of range-size as assessed by PGLS, and
usually not correlated between them) were finally used
as biogeographic factors. In those lineages in which both
variables (maxLat and maxLon) were significantly correlated, only the main determinant of range size was used.
We used a stepwise model selection procedure to
select the multiple linear regression models with the

smallest Akaike’s Information Criterion (AIC). To
account for multiple comparisons we applied the Bonferroni correction.

Results
Phylogenetic signal

Range size showed significant phylogenetic signal (as measured with a randomization test) in four of the ten lineages,
displaying relatively low values of the K statistic (Table 2).
However, no phylogenetic signal remained statistically significant for range size after Bonferroni correction. The
maximum longitude and the longitude of centroid showed
significant phylogenetic signal for most of the studied
lineages (the exceptions were Ilybius, Enicocerus and
Hydrochus, the former two encompassing few taxa) with
values of K generally high, while minimum longitude, maximum latitude, and the latitude of centroid showed significant phylogenetic signal in four of the lineages. After
Bonferroni correction, only some lineages showed significant phylogenetic signal, with maximum longitude displaying the higher number of significant cases.
The average size of biomes did not show phylogenetic
signal in any lineage whereas niche breadth, as estimated by number of biomes overlapping with geographic range, displayed phylogenetic signal only for the
H. dentipes and Graptodytes lineages. Three lineages did
not exhibit phylogenetic signal for any of the range attributes: Ilybius, Enicocerus and Hydrochus.

Table 2 Phylogenetic signal (K statistic)
Lineage

Size

maxLon

minLon

maxLat

minLat

LonC

LatC

avB

nB

Ilybius

0.06
(0.787)

0.24
(0.076)

0.11
(0.456)

0.13
(0.418)

0.16
(0.201)

0.16
(0.189)

0.23
(0.097)

0.07
(0.729)

0.11
(0.565)

Deronectes

0.22
(0.386)

0.91
(0.001*)

0.63
(0.038*)

0.19
(0.581)

0.41
(0.037*)

0.91
(0.003**)

0.26
(0.262)

0.25
(0.228)

0.31
(0.215)

Enicocerus

0.48
(0.777)

0.60
(0.572)

0.65
(0.525)

0.30
(0.977)

0.74
(0.547)

0.59
(0.613)

0.32
(0.972)

0.42
(0.861)

0.42
(0.923)

Limnebius

0.76
(0.034*)

1.06
(0.042*)

0.73
(0.041*)

1.23
(0.003**)

0.43
(0.315)

0.90
(0.046*)

1.00
(0.009*)

0.47
(0.186)

0.72
(0.071)

H. gracilis

0.59
(0.052)

0.829
(0.011*)

0.329
(0.515)

0.28
(0.655)

0.69
(0.017*)

0.69
(0.018*)

0.26
(0.730)

0.22
(0.836)

0.54
(0.111)

H. dentipes

0.60
(0.046*)

1.30
(0.000**)

0.73
(0.008*)

1.11
(0.000**)

0.21
(0.690)

1.22
(0.000**)

0.78
(0.008*)

0.50
(0.086)

0.82
(0.013*)

Phothydraena

0.16
(0.841)

0.70
(0.039*)

0.85
(0.046*)

0.33
(0.542)

0.49
(0.243)

1.08
(0.005**)

0.74
(0.105)

0.63
(0.059)

0.20
(0.668)

Graptodytes

0.30
(0.019*)

0.62
(0.001**)

0.27
(0.069)

0.39
(0.008*)

0.22
(0.067)

0.55
(0.000**)

0.65
(0.000**)

0.19
(0.099)

0.33
(0.009*)

Hydroporus

0.57
(0.008*)

0.81
(0.001**)

0.31
(0.318)

0.62
(0.018*)

0.64
(0.022*)

0.69
(0.003**)

0.92
(0.001**)

0.36
(0.289)

0.32
(0.119)

Hydrochus

0.73
(0.394)

0.88
(0.173)

0.80
(0.45)

0.81
(0.258)

0.62
(0.617)

0.87
(0.192)

0.82
(0.226)

0.40
(0.898)

0.72
(0.375)

Phylogenetic signal as estimated with K statistic for different range attributes. The P-value, based on the variance of phylogenetically independent contrasts
relative to tip shuffling randomization, is provided in parenthesis. Asterisks indicate significant P-values: * P < 0.05; ** P < 0.005 (Bonferroni critical value for ten
tests). Codes: Size, range size (log-transformed); maxLong and minLong, maximum and minimum longitude of ranges, respectively; maxLat and minLat, maximum
and minimum latitude, respectively; LonC and LatC, longitude and latitude of centroids, respectively; avB, average size of the biogeographic provinces that partly
or completely overlap with the species ranges (log-transformed); nB, number of biogeographic provinces that partly or completely overlap with the species
ranges.

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The phylogenetic eigenvector regression (PVR) gave in
general a stronger phylogenetic signal than the randomization tests. This was especially evident in Ilybius, for
which PVR showed high levels of phylogenetic signal in
contrast with non significant K values. Range-size
showed moderate levels of phylogenetic signal, but some
descriptors of the spatial position of ranges had higher
levels (Table 3), which remained mostly significant after
Bonferroni correction. Notably, a high fraction of the
variance in the northern longitudinal limits and longitudinal centroids of the ranges in most lineages was
explained by phylogenetic relationships among species.
As happened with the randomization tests, the average
size of biomes and the number of biomes were rarely
correlated with phylogeny (Table 3).
Among the lineages with species with both habitat types
(lotic and lentic), habitat type exhibited significant phylogenetic signal for Hydroporus, as computed with Pagel’s l
(l = 0.89, P < 0.01), but not for “Phothydraena“ (l < 0.00,
P = 1.0), Graptodytes (l < 0.00, P = 0.4) or Hydrochus (l =
1, P = 0.3). Estimates of the phylogenetic signal with the K
statistic gave similar results, with Hydroporus exhibiting
significant signal (K = 0.63, P < 0.01) but not the remaining lineages (Phothydraena, K = 0.17, P = 0.9; Graptodytes,
K = 0.15, P = 0.3; Hydrochus, K = 0.98, P = 0.1).
Ecological tolerance

Range size was significantly and positively correlated
with both the spatial extent and the number of biomes
in which species are found in most of the tested
lineages, as measured after phylogenetic correction with
PGLS correlations (Table 4). Correlations remained significant after Bonferroni correction only in the case of
the number of occupied biomes.
Dispersal ability

Habitat preference, taken as a surrogate of dispersal
ability, was significantly and positively correlated with

range-size after phylogenetic correction with PGLS in
those lineages with both lotic and lentic species, with
the only exception of Hydrochus (Table 4). Correlation
values were particularly high for Phothydraena and
Graptodytes, which remained significant after Bonferroni
correction.
Geographic location

After phylogenetic correction, range size was significantly and positively correlated with maximum latitude
and longitude for most of the lineages, with the only
exceptions of Limnebius (marginally significant) and
Phothydraena (Table 4; see also Figure 1). These positive correlations remained significant for maximum latitude after Bonferroni correction for multiple tests.
Maximum latitude and longitude had also the highest
correlation values for most of the lineages. The latitude
and longitude of the centroid were correlated with the
size of geographic range in four and five of the ten
lineages respectively: Enicocerus, Hydraena dentipes,
Graptodytes and Hydroporus, plus Ilybius in the case of
latitude of the centroid (Table 4). Minimum longitude
and latitude were only significantly correlated with
range size in Ilybius and Hydrochus respectively, in both
cases with a negative correlation (Table 4). Range size in
Phothydraena was not significantly correlated with any
of the range proprieties studied, although minimum latitude was marginally significant (Table 4).
Age and area

The preferred model for the plot of global geographic
range size against species age was in all cases a straight
line, i.e. quadratic regression did not provide a significantly better fit to the data than did linear regression
(Figure 2; see also Additional file 2, Table S2). The general tendency was to increase range size with evolutionary age, but with the sole exception of the H. dentipes
lineage (with a significant positive relationship) the

Table 3 PVR coefficients
Lineage
Ilybius

Size

maxLon

minLon

maxLat

minLat

LonC

LatC

avB

nB

0.843**

0.983**

1.000**

0.719**

0.651**

0.862**

0.222

0.103

0.904**

Deronectes

0.148

0.981**

0.343*

0.329*

0.470**

0.953**

0.462*

0.211*

0.160*

Enicocerus

0.475*

0.401

0.425

0.858**

0.413

0.507*

0.640*

0.316

0.301

Limnebius

0.457*

0.968**

0.766*

0.936**

0.681*

0.932**

0.458*

1.000**

0.358

H. gracilis

0.581*

0.990**

0.558*

0.601*

0.367*

0.256

0.786**

0.236

0.564*

H. dentipes
Phothydraena

0.668**
0.550*

0.950**
0.743*

0.948**
0.599*

0.631**
0.344

0.206**
0.480*

0.946**
0.984**

0.389**
0.870**

0.883**
0.411*

0.391*
0.537*

Graptodytes

0.567*

0.897*

0.644**

0.427*

0.185

0.687**

0.975**

0.492**

0.702*

Hydroporus

0.943**

0.737**

0.910**

0.979**

0.688**

0.709**

0.747**

0.852**

0.402*

Hydrochus

0.489

0.371*

0.987**

0.208

0.238

0.822**

0.415*

0.236

0.270

Coefficients of determination of Phylogenetic Eigenvector Regression (PVR) models for the different lineages studied. Variable codes as in Table 2. Size, range size
(log-transformed). Models with significant P-values are indicated with asterisks: * P < 0.05; ** P < 0.005 (Bonferroni critical value for ten tests).

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Table 4 PGLS tests for associations between range-size and biogeographical and ecological variables
Variables
Lineage
Ilybius

maxLon
a

minLon

maxLat

minLat

LonC

LatC

avB

nB

15.5

15.5

15.5

15.5

15.5

15.5

15.5

15.5

r

0.50

0.18

0.67

0.133

0.015*

0.378

a

15.5

15.5

13.95

15.5

15.5

15.5

15.5

15.5

0.43

-0.06

0.74

-0.32

0.22

0.29

0.62

0.81

0.027*

0.974

0.000**

0.164

0.224

0.183

0.001**

0.000**

a
r

15.5
0.86

15.5
0.59

15.5
0.88

15.5
-0.02

15.5
0.8

15.5
0.78

4.6
0.75

4.66
0.91

0.003**

0.096

0.002**

0.955

0.01

0.014*

0.026*

0.000**

a

4.16

2.15

4.99

1.10

2.89

4.50

2.23

10.62

0.60

-0.56

0.62

-0.54

0.20

0.41

0.74

0.89

0.08

0.091

0.069

0.092

0.641

0.298

0.013*

0.000**

a

9.91

1.86

2.89

3.56

4.53

2.01

11.7

15.5

r

0.67

-0.32

0.66

-0.28

0.35

0.53

0.55

0.67

P
a

0.006*
15.5

0.513
2.86

0.007*
15.5

0.181
2.29

0.111
15.5

0.067
15.5

0.032*
3.5

–

0.000**

P

H. dentipes

-0.27

0.317

r
H. gracilis

-0.26

0.000**

P
Limnebius

0.74

0.010*

P
Enicocerus

-0.50

0.888

r

Deronectes

0.08

P

Hab

0.014*
5.37

–

–

–

–

–

r

0.15

0.64

0.71

0.53

0.71

0.000**

0.717

0.002**

0.000**

0.014*

0.000**

a

15.5

15.5

15.5

15.5

15.5

15.5

15.5

15.5

0.29

-0.17

0.42

-0.60

0.06

0.08

0.23

0.38

0.76

0.494

0.65

0.269

0.095

0.919

0.84

0.607

0.353

0.019*

a

15.5

1.87

7.66

15.5

15.5

15.5

3.41

15.5

3.64

r
P

0.74
0.000**

-0.43
0.579

0.85
0.000**

0.301
0.156

0.525
0.017*

0.79
0.000**

0.09
0.847

0.67
0.014*

0.84
0.000**

a

2.33

2.15

3.18

1.95

4.98

6.56

3.35

4.08

5.36

r

Hydroporus

0.84

0.395

P
Graptodytes

0.01

0.000**

r

Phothydraena

0.84

P

0.75

-0.32

0.86

-0.16

0.5

0.74

0.61

0.84

0.53
0.001**

14.59

P

0.000**

0.3013

0.000**

0.433

0.001**

0.000**

0.000**

0.000**

a

3.50

4.36

15.5

2.66

4.32

15.5

15.5

15.5

3.71

r

0.69

-0.06

0.78

-0.61

0.39

0.49

0.57

0.65

0.27

P

Hydrochus

0.010*

0.859

0.002*

0.034*

0.185

0.091

0.041*

0.015*

0.398

Results of phylogenetic comparative tests for associations between range-size and biogeographical and ecological variables using Phylogenetic Generalized Least
Squares. The maximum likelihood estimate of evolutionary constraint (alpha, a) is provided, and parameter estimates given that maximum likelihood. Significant
relations (regression slope significantly different of zero) are given in asterisks: * P < 0.05; ** P < 0.005 (Bonferroni critical value for ten tests).

values of the slopes of the lines that best predicted
range-size from species age were not significantly different from zero (Additional file 1, Table S2), indicating a
non significant increase or decline of range size with
age.
Multiple regression models

We assessed the relative importance of the phylogenetic
vs. ecological and geographic factors in determining the
size of the geographical range through the use of multiple regression models. The percentage of variance
explained was in general very high, ranging from ca.
60% to more than 98% (Table 5).
For most of the lineages, the maximum latitudinal
limit of the geographic range was the most influential
variable explaining range size (Table 5). The only exception was Phothydraena, for which we used minimum

latitude in the model, according to the results of the
PGLS analyses (see above).
Although phylogenetic effects had often less influence
than biogeographic factors, they were usually retained in
the models, and for some lineages were the most important (Ilybius, Limnebius and H. gracilis). Habitat preference was retained in the model for Phothydraena (in
which was the main range-size determinant) and Graptodytes, but not in Hydroporus or Hydrochus, in which
both biogeographic and phylogenetic factors were
included in the model. Species’ age was not retained in
any of the models.

Discussion
Range-size heritability has sparked an intense debate in
the literature in the last years, although no clear conclusions have been drawn, partly because of the variability

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Figure 1 Northern latitudinal limit against range size. Influence of the northern latitudinal limit on geographic range size (log-transformed).
Raw data points and standard least squares regression line (solid line), without phylogenetic control, are showed for illustrative purposes. The
coefficient of determination and the regression line (dotted line) as calculated using Phylogenetic Generalized Least Squares are also provided.

in the methods employed and the quality of the data
used [12,13,67,68] (see [69] for a review). If geographic
range sizes are determined by life-history, ecological or
physiological characters, it may be expected to find

some degree of phylogenetic signal through the cladogenetic process [7,70,71]. Evidence of low phylogenetic signal in range size has been reported in a number of
previous studies for different taxonomic groups

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Figure 2 Range size against species age. Plots of geographic range size against species age (Myr). The coefficient of determination is
provided. With the single exception of H. dentipes, slope was not significantly different of 0 in all the studied lineages. The regression line and
the 95% confidence interval are also displayed. Grey dots are outliers.

[14,16,25,29,72-74], the conclusion being that range size
is an extremely labile trait. However, as showed by Pigot
et al. [75], low phylogenetic signal cannot be taken as
strong evidence for the lability of geographic ranges. In

our case, both the randomization test [15] and the PVR
method [35] showed some positive significant phylogenetic signal for several lineages. This phylogenetic signal
was relatively weak when compared with other range

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Table 5 Stepwise multiple regression models explaining
range size
Ilybius

R2

F

P

Variables

b

t

P

75.5

23.66

0.000

maxLat

0.38

3.16

0.004

PVR24

Lineage

-0.50

-4.39

0.000

0.35
0.70

3.09
5.26

0.005
0.000

Deronectes

63.2

18.03

0.000

PVR20
maxLat
PVR19

0.31

2.34

0.030

Enicocerus

98.6

121.15

0.000

maxLat

0.52

6.89

0.001

maxLon

0.47

7.83

0.001

PVR4

-0.18

-2.83

0.036

Limnebius

75.9

11.01

0.007

maxLat

0.55

2.96

0.021

PVR5

-0.60

-3.18

0.016

0.58
-0.45

3.33
-2.56

0.007
0.027

H. gracilis

69.2

12.35

0.002

maxLat
PVR1

H. dentipes

72.3

46.96

0.000

maxLat

0.85

6.85

0.000

Phothydraena

81.8

13.49

0.006

minLat

-0.51

-2.89

0.028

Habitat1

0.69

3.94

0.008

Graptodytes

88.8

36.89

0.000

maxLat

0.68

7.06

0.000

PVR8

-0.32

-3.36

0.005

Habitat0

-0.26

-2.75

0.016

maxLat
PVR4

0.70
-0.36

10.93
-5.77

0.000
0.000

Hydroporus

91.7

69.29

0.000

PVR7
78.6

18.31

0.000

-2.91

0.008

0.19

3.15

0.004

maxLat

0.59

3.72

0.004

PVR8

Hydrochus

-0.17

PVR21

0.46

2.90

0.016

Summary table for the stepwise multiple regression models explaining range
size in the different lineages. We show for each model the explained variance
(R2 in percentage) and its significance (F and P values). For each variable
included in the model, the fitted standardized regression coefficient (b) and
its corresponding significance (t and P values) are shown. Variable codes as in
Table 2. PVR# refers to phylogenetic vectors used in PVR approach.

properties, but still strong enough to be kept as a relevant factor in the multiple regression models (see
below). The low taxonomic level of the studied phylogenies could contribute to the lack of significance in the
randomization tests of phylogenetic signal for some of
the groups [69], as well as the low number of species in
some of them (computer simulations demonstrate that
this test requires approximately 20 species to achieve a
statistical power of 80%, [17]). Nevertheless, the values
of the K statistic do not depend on sample size, and it is
considered a valid descriptive statistic of the amount of
phylogenetic signal even for small data sets [17]. The
PVR method has a good performance with small phylogenies [76], and in consequence our results from this
approach could be more reliable.
The geographic location of the species had the strongest phylogenetic signal of all the variables tested. With
the question of the heritability of the size of geographic
ranges monopolizing all the attention in the literature,
the role of phylogenetic constraints on other attributes
of species’ ranges, such as geographic position, have

remained nearly unexplored (but see [73]). Our results
show that, in general, the geographic position of species’
ranges display a stronger phylogenetic signal than their
size. This is what would be expected under a vicariant
mode of speciation in which the ancestral range is split
almost randomly (hence partly erasing the phylogenetic
signal of range size), but the resulting species maintain
the geographic centroid of their ranges through time, so
that range movements do not erase completely the geographic signal of speciation. This would justify the use
of the present distribution of species to infer speciation
processes (e.g., [46,77]), contrary to the view that rapid
changes to species geographic ranges effectively eliminate any relationship between the geography of speciation and contemporary locations of geographic ranges
[78]. In the case of water beetles, a review of the direct
evidence provided by Quaternary remains also support a
general pattern of range stability through the last Glacial
cycle, contrary to the extended view of generalized
major range shifts due to climatic change [79].
When biogeographic, phylogenetic and ecological factors were combined to explain range size differences,
the northern limit of the geographic range was generally
the main determinant of geographic range size. In a
number of terrestrial groups range sizes are known to
strongly increase with latitude in the Palearctic and
Nearctic above 40°-50°N [26], in agreement with Rapoport’s rule (see [80] for a review). In the Western
Palearctic, widespread species tend to have a central and
north European distribution, and among the water beetles in these areas there are few, if any, species with
restricted distributions [32]. In the same way, there are
many examples of water beetle lineages including narrow endemics in which the widespread species have the
southern limit of their ranges at the edge of the southern peninsulas.
The strong role of geographic location in determining
range size can be grounded in different lines of argument. From an ecological perspective, latitudinal/longitudinal gradients can represent a particular case of the
more general relationship between the niche breadth of
a species and the size of its geographic range (e.g.,
[2,21,81-83]). Climatic changes and the drastic changes
in ecological conditions were specially dramatic in
northern latitudes of the Palearctic region, and might
have operated as ecological filters [84], with only those
species displaying broad ecological niches (and consequently wide ranges) being able to persist in northern
regions or re-colonize northern areas from southern
refugia after the glaciations. In the studied lineages,
maximum latitude was usually highly correlated with
niche breadth (Additional file 1, Table S3), showing that
those species reaching more northern latitudes display
broader ecological niches. Species with narrow niches

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would have remained restricted to southern areas, less
affected by the climatic changes. This is valid also for
longitude, with species reaching the more continental
parts of Eurasia being more affected by climatic changes.
The absence of fossil remains of southern species of
aquatic Coleoptera among the abundant central and
northern European Quaternary records [79] would support this view, as well as the recognition of the Mediterranean peninsulas as an area of endemism, not as a
source of postglacial colonisation (e.g., [85]).
The Western Palearctic has strong ecological constraints in the south and the west (the seas and oceans),
which might result in most species having a distribution
centre towards the east or the north. The larger range
size of the species with a more northern and eastern
distribution could thus be the result of a geometric constraint. The species with the largest ranges necessarily
include the largest available surfaces, i.e. from central
Europe to the east. Any species expanding its range to
cover the biogeographical area of the lineages included
here will end up with a distribution centroid in the
north-east, as species with large distributions approaching the size of a bounded domain are constrained to
have their centroid near the centre of the domain [86].
The general negative correlation between minimum latitude and range size (Table 2) is compatible with this
geometric effect, showing that widespread species also
expand their ranges to the south. But this geometric
constraint cannot be the sole explanation for the patterns we found, as this would not explain the phylogenetic signal for both range size and geographical
position. The strong positive relationship between maximum latitude and range size shows the asymmetry of
the range expansions, with an origin in southern refugia,
as also found for European land snails [87]. A more uniform distribution of the ancestral ranges may result in a
similar position of the final centroids of the species with
expanding ranges, but not in a strong positive relationship between maximum latitude and range size.
Two additional biogeographic factors emerged as
highly correlated with range size, the spatial extent and
the number of biomes in which species are found. If
species can expand their distribution more easily within
than across biogeographic boundaries, then species
found in biogeographic biomes with a large spatial
extent should have larger range sizes than species found
in small biomes ([26,88-90]; see [14,25] for examples of
application in range-size analyses). The number of
biomes can be related with niche breadth differences,
since some species are restricted to one (or few) biomes
due to habitat specificity while others are able to expand
easily their distribution across biomes (Additional file 2),
although in this case results are confounded by the unavoidable circularity of the relationship between range

Page 12 of 15

size and number of biomes. The heterogeneity of
biomes is certainly not uniform over the whole continent, with more climatic and ecological variety in the
south associated with the main mountain ranges and
the influence of the Mediterranean.
Habitat type was also positively correlated with rangesize in those lineages with both lotic and lentic species
(the only exception was the genus Hydrochus), showing
that in the same lineage, and after accounting for possible phylogenetic effects, species inhabiting lentic water
bodies display larger distributional ranges than those
inhabiting lotic ones, with species inhabiting both types
of environments with intermediate range sizes. This is
in agreement with previous studies across multiple
lineages of freshwater invertebrates, which have shown
that lotic species have on average smaller geographical
ranges than the lentic species [22,23]. Although most of
species included here are winged, there is no information about the flying capacity across species within each
one of the lineages, so direct measures of dispersal ability are not available. The differences in spatial and temporal persistence between lotic and lentic habitats (small
lentic water bodies tend to fill with sediment over a
time period of decades or centuries, while rivers and
streams persist over geologically defined time periods)
have been postulated as resulting in consistent differences in dispersal strategies and colonization abilities
between species living in both types of aquatic environments (see [24] for an overview), providing a surrogate
measure of dispersal ability. Since colonization rates
depend not only on dispersal abilities, but also on the
geographic configuration of habitats, a potential confounding factor could be the differential distribution of
suitable habitat between lotic and lentic environments
(e.g., a contrasting degree of spatial clustering or a spatial correlation of habitat availability with latitude).
Nevertheless, different recent studies have consistently
provided evidence against differences in habitat availability, lending further support to the hypothesis that
lentic species have a higher propensity for dispersal than
lotic species [91-93]. Although dispersal abilities are
among the more commonly cited potential determinants
of a species’ range (see e.g., [94]), this relation has rarely
been assessed correcting for phylogeny.
We did not find evidence to support a clear pattern of
range size change over time in water beetle lineages.
The relationship between age vs. range-size plots suggested that species’ time since divergence is positively
correlated with geographic range size, in agreement with
the “range and area” model [28], but the values of the
slopes of the lines that best predicted range-size from
species age were for most groups not significantly different from zero. Thus, our results are compatible with a
“stasis” [15] or an idiosyncratic model, were there is no

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reason to expect a directional change in geographic
range size through time. In any case, the amount of variance in geographic range size explained by phylogenetic
age was generally low, as shown by r2 values. The lack
of a general pattern of the changes in geographic range
size over evolutionary time is a common result across a
wide range of clades (e.g., [15,29,31,95]. The variability
of the type and quality of data used and analyses performed has been viewed as a possible explanation for
this lack of consistency [29,95], but our results, using
different lineages and a common methodology and dataset, proved to be equally variable and clade-specific,
pointing to a true lack of relationship between age and
area, despite the uncertainties in the sampling and the
delimitation of the ranges (see below).
Other factors not considered in this study may be of
relevance in determining geographic range sizes, such as
thermal tolerance, body size, population abundance or
colonization and extinction dynamics [3]. Similarly, we
are aware that our analyses could be weakened by
incomplete taxon sampling in some groups and uncertainties in the estimated geographic range sizes. Uncertainties associated to phylogenies are another possible
source of error, as missing or extinct taxa would result
in the overestimation of the phylogenetic age of the
related species. Despite these obvious limitations, the
consistency of the results and the high percentage of
variance explained by the factors included (between ca.
60 and 98%, Table 5) allows to draw firm conclusions
applicable to a wide range of phylogenetically independent groups of Coleoptera.

Conclusions
Our findings show that range size of a species is shaped
by an interplay of geographic and ecological factors,
with a phylogenetic component affecting both of them.
The understanding of the factors that determine the size
and geographical location of the distributional range of
species is fundamental to the study of the origin and
assemblage of the current biota. Our results show that
for this purpose the most relevant data may be the phylogenetic history of the species and its geographical
location, in agreement with results from some previous
studies (e.g. [14,25]).
Additional material
Additional file 1: Data used in the study. Taxa included in the
different studied lineages with data on geographic range properties and
ecological attributes. Accession numbers of the sequences are also
indicated.
Additional file 2: Supplementary tables. Tables S1-S3.
Additional file 3: Ultrametric trees for the different lineages.
Numbers indicate node support: above nodes, Bayesian posterior

Page 13 of 15

probabilities (if above 0.5); below nodes, bootstrap support values from
Maximum Likelihood analysis (if above 50%).

Acknowledgements
We would thank to M. Jäch, H. Fery, H.V. Shaverdo and A. Hidalgo for
providing information on the distribution of some species. We thank also T.
Barraclough, J.-C. Svenning and two anonymous reviewers for helpful
comments on earlier versions of the manuscript. This research was
supported by a postdoctoral fellowship from the Seneca Foundation
(Regional Agency of Science and Technology, Murcia, Spain) to P.A. and
projects CGL2007-61665 and CGL2010-15755 to I.R.
Author details
Institute of Evolutionary Biology (CSIC-UPF), Passeig Maritim de la
Barceloneta 37, 08003 Barcelona, Spain. 2Department of Bioscience, Aarhus
University, Ny Munkegade 114, DK-8000 Aarhus C, Denmark.
1

Authors’ contributions
Both authors designed and performed research, carried out data compilation
and analyses, and participated in preparation of the manuscript. Both
authors read and approved the final manuscript.
Received: 5 September 2011 Accepted: 28 November 2011
Published: 28 November 2011
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doi:10.1186/1471-2148-11-344
Cite this article as: Abellán and Ribera: Geographic location and
phylogeny are the main determinants of the size of the geographical
range in aquatic beetles. BMC Evolutionary Biology 2011 11:344.

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