Functional diversity is an important aspect of biodiversity, but its relationship
to species diversity in time and space is poorly understood. Here we
compare spatial patterns of functional and taxonomic diversity across
marine and terrestrial systems to identify commonalities in their respective
ecological and evolutionary drivers. We placed species-level ecological
traits into comparable multi-dimensional frameworks for two model systems,
marine bivalves and terrestrial birds, and used global speciesoccurrence
data to examine the distribution of functional diversity with latitude
and longitude. In both systems, tropical faunas show high total
functional richness (FR) but low functional evenness (FE) (i.e. the tropics
contain a highly skewed distribution of species among functional groups).
Functional groups that persist toward the poles become more uniform in
species richness, such that FR declines and FE rises with latitude in both systems.
Temperate assemblages are more functionally even than tropical
assemblages subsampled to temperate levels of species richness, suggesting
that high species richness in the tropics reflects a high degree of ecological
specialization within a few functional groups and/or factors that favour
high recent speciation or reduced extinction rates in those groups.
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Contrasting responses of functional diversity to major losses in taxonomic diversity
Taxonomic diversity of benthic marine invertebrate shelf species
declines at present by nearly an order of magnitude from the
tropics to the poles in each hemisphere along the latitudinal
diversity gradient (LDG), most steeply along the western Pacific
where shallow-sea diversity is at its tropical maximum. In the
Bivalvia, a model system for macroevolution and macroecology,
this taxonomic trend is accompanied by a decline in the number
of functional groups and an increase in the evenness of taxa
distributed among those groups, with maximum functional evenness
(FE) in polar waters of both hemispheres. In contrast, analyses
of this model system across the two era-defining events of
the Phanerozoic, the Permian–Triassic and Cretaceous–Paleogene
mass extinctions, show only minor declines in functional richness
despite high extinction intensities, resulting in a rise in FE
owing to the persistence of functional groups. We hypothesize
that the spatial decline of taxonomic diversity and increase in FE
along the present-day LDG primarily reflect diversity-dependent
factors, whereas retention of almost all functional groups through
the two mass extinctions suggests the operation of diversity-independent
factors. Comparative analyses of different aspects
of biodiversity thus reveal strongly contrasting biological consequences
of similarly severe declines in taxonomic diversity and
can help predict the consequences for functional diversity among
different drivers of past, present, and future biodiversity loss.
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- Award ID(s):
- 1633535
- NSF-PAR ID:
- 10077244
- Date Published:
- Journal Name:
- Proceedings of the National Academy of Sciences of the United States of America
- Volume:
- 115
- ISSN:
- 0027-8424
- Page Range / eLocation ID:
- 732 -737
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Location Central Texas.
Time period Late Pleistocene to Present.
Major taxa studied Mammals.
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Abstract Aim We investigate geographic patterns across taxonomic, ecological and phylogenetic diversity to test for spatial (in)congruency and identify aggregate diversity hotspots in relationship to present land use and future climate. Simulating extinctions of imperilled species, we demonstrate where losses across diversity dimensions and geography are predicted.
Location North America.
Time period Present day, future.
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