Dispersal
|
departure/transfer
|
Clade
|
categorical:
plants, animals
|
…plants, as sessile and passive dispersers, may be more affected
by dispersal limitation than animals.
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Dispersal type
|
categorical:
passive, active, mixed
|
…passive dispersers, being dependent on external sources for
their dispersal, may be more affected by dispersal limitation than
active dispersers.
|
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Realm |
categorical: terrestrial, marine, freshwater |
…species in marine systems are less affected by dispersal
limitation than those in terrestrial/freshwater systems, because marine
systems might have higher connectivity. |
|
settlement
|
Temperature regulation
|
categorical: endotherm, ectotherm
|
…endotherms are less affected by niche limitation than ectotherms
due to broad thermal tolerances, allowing them to attain and persist in
larger ranges more easily.
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Biogeographical region size |
continuous |
…species in
regions with less available (niche) space (e.g., smaller regions) may be
less affected by dispersal limitation than species with more space
available, because in smaller regions even less dispersive species may
have attained maximum range sizes. |
|
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Habitat correction |
categorical: single habitat, yes, no. |
…available niche space rather than colonization ability may be
the limiting factor when it comes to dispersal. |
|
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Available space correction |
categorical: unique site, yes, no. |
…dispersal limitation and (maximum) range sizes may differ
between regions or habitats of difference sizes (also see
‘Biogeographical region size’ for specific predictions). |
Evolution
|
evolutionary history
|
Species age
|
categorical: considered, no considered
|
…time for range expansion rather than dispersal ability may be
the limiting factor when it comes to understanding differences in range
sizes across species.
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Phylogenetic correction |
categorical: considered, not considered |
…dispersal ability and range size may be phylogenetically and
temporally correlated, thus correcting for phylogenetic dependence might
reduce or remove the effect of evolution on the
relationship. |
|
past dynamics
|
Latitude
|
categorical: tropical, subtropical, temperate, multiple latitudes
|
…species in tropical regions may be less affected by dispersal
limitation because of long-term environmental stability (e.g., lack of
glaciations), thus more time for range expansion. Tropical species may
therefore have had more opportunity to attain and persist in their
maximum range sizes, compared with temperate regions.
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Latitude correction |
categorical: unique latitudinal zone, yes, no. |
…dispersal limitation and (maximum) range sizes may differ
between latitudes (also see ‘Latitude’ for specific
predictions). |
Methodology
|
dispersal approximation
|
Number of dispersal-related traits
|
continuous
|
…the dispersal process may not be accurately approximated when
including only few traits that lack the components of dispersal most
relevant for range expansion.
|
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range size definition
|
Range size metric
|
categorical:
extent of occurrence, area of occupancy
|
…area of occupancy can underestimate range size by excluding
discontinuities in the spatial distribution of taxa, resulting in a
mismatch between range size and dispersal.
|
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Range size completeness |
categorical: partial, complete |
…partial ranges may underestimate true range
sizes. |
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taxonomic delimitation
|
Taxonomic unit
|
categorical:
species, non-species
|
…using higher taxonomic levels as units of analysis (e.g.,
‘genus’, ‘family’) ignores species-level variation in dispersal ability
and range size.
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Taxonomic breadth |
categorical: genus, family, order, class,
phylum/division |
…identifying universal dispersal-related traits
associated with range size at very broad taxonomic levels (e.g.,
‘phylum’, ’division’) may be difficult. |
|
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Number of species |
continuous |
… a higher number of species
increases statistical power, captures a higher trait and range size
variation, and may be less biased by incomplete sampling of species
within the study system. |