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Missing species among Mediterranean non-Siphonophoran Hydrozoa.

Gravili C, Bevilacqua S, Terlizzi A, Boero F - Biodivers. Conserv. (2015)

Bottom Line: Realistic assessments of species pools require addition of new species, but also subtraction of species not found since a certain period.As consequence, the regional biodiversity should be analyzed through its temporal evolution, to detect changes and their possible causes.This approach has profound consequences on biodiversity assessments and also on the compilation of red lists.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Zoology and Marine Biology, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Di.S.Te.B.A., Università del Salento, Via Prov.le Lecce-Monteroni, 73100 Lecce, Italy.

ABSTRACT

Hydrozoa of the Mediterranean Sea are well known and a recent monograph covers 457 species. Mediterranean non-Siphonophoran Hydrozoa comprises 398 species, an increasing number due to continuous updates, representing about 10 % of the 3,702 currently valid species reported in a recent world assessment of hydrozoan diversity. Many new records are non indigenous species, previously described species that occurred elsewhere and whose arrival was presumably caused by human activities. However, many species reported in the past are not recorded in recent times. Realistic assessments of species pools require addition of new species, but also subtraction of species not found since a certain period. With the confidence of extinction index, cases of putative extinction can be raised. Out of the 398 known species, only 162 (41 %) have been reported in the last decade, while 53 (13 %) are not recorded in the literature since at least 41 years. According to the confidence of extinction index, 60 % of the 53 missing species are extinct, and 11 % are putatively extinct from the basin. From a biogeographical point of view, the missing species are: 34 % endemic, 19 % boreal, 15 % Mediterranean-Atlantic, 11 % Indo-Pacific, 11 % circumtropical, 4 % cosmopolitan, 2 % tropical-Atlantic, 4 % non-classifiable. Fluctuations in species composition into a certain area cause heavy variability in the expression of both structural and functional biodiversity. As consequence, the regional biodiversity should be analyzed through its temporal evolution, to detect changes and their possible causes. This approach has profound consequences on biodiversity assessments and also on the compilation of red lists.

No MeSH data available.


Related in: MedlinePlus

Average taxonomic distinctness (a) and variation in taxonomic distinctness (b) of Mediterranean NSH species pool in each of the five periods (>40, 40, 30, 20, 10 years) plotted against the corresponding total number of species characterizing each period. For both indices, the expected mean (dotted line) and the 95 % confidence limits (solid lines) were also plotted from 1,000 independent simulations drawn randomly from the full list of Mediterranean NSH species
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Fig5: Average taxonomic distinctness (a) and variation in taxonomic distinctness (b) of Mediterranean NSH species pool in each of the five periods (>40, 40, 30, 20, 10 years) plotted against the corresponding total number of species characterizing each period. For both indices, the expected mean (dotted line) and the 95 % confidence limits (solid lines) were also plotted from 1,000 independent simulations drawn randomly from the full list of Mediterranean NSH species

Mentions: Results form analyses on taxonomic distinctness highlighted a decrease of both Δ+ and Λ+ of the Mediterranean NSH species pool through time (Fig. 5). The species pool of >40y showed significantly higher values (P < 0.05) of Δ+ and Λ+, indicating a higher breadth and heterogeneity of taxonomic structure. In contrast, the species pool in the last decade (10 years) exhibited values of Δ+ and Λ+ significantly below random expectation, indicating that Mediterranean NSH species were more closely related than expected by chance, with a significant reduction of taxonomic distinctness (Fig. 5).Fig. 5


Missing species among Mediterranean non-Siphonophoran Hydrozoa.

Gravili C, Bevilacqua S, Terlizzi A, Boero F - Biodivers. Conserv. (2015)

Average taxonomic distinctness (a) and variation in taxonomic distinctness (b) of Mediterranean NSH species pool in each of the five periods (>40, 40, 30, 20, 10 years) plotted against the corresponding total number of species characterizing each period. For both indices, the expected mean (dotted line) and the 95 % confidence limits (solid lines) were also plotted from 1,000 independent simulations drawn randomly from the full list of Mediterranean NSH species
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4514666&req=5

Fig5: Average taxonomic distinctness (a) and variation in taxonomic distinctness (b) of Mediterranean NSH species pool in each of the five periods (>40, 40, 30, 20, 10 years) plotted against the corresponding total number of species characterizing each period. For both indices, the expected mean (dotted line) and the 95 % confidence limits (solid lines) were also plotted from 1,000 independent simulations drawn randomly from the full list of Mediterranean NSH species
Mentions: Results form analyses on taxonomic distinctness highlighted a decrease of both Δ+ and Λ+ of the Mediterranean NSH species pool through time (Fig. 5). The species pool of >40y showed significantly higher values (P < 0.05) of Δ+ and Λ+, indicating a higher breadth and heterogeneity of taxonomic structure. In contrast, the species pool in the last decade (10 years) exhibited values of Δ+ and Λ+ significantly below random expectation, indicating that Mediterranean NSH species were more closely related than expected by chance, with a significant reduction of taxonomic distinctness (Fig. 5).Fig. 5

Bottom Line: Realistic assessments of species pools require addition of new species, but also subtraction of species not found since a certain period.As consequence, the regional biodiversity should be analyzed through its temporal evolution, to detect changes and their possible causes.This approach has profound consequences on biodiversity assessments and also on the compilation of red lists.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Zoology and Marine Biology, Dipartimento di Scienze e Tecnologie Biologiche e Ambientali, Di.S.Te.B.A., Università del Salento, Via Prov.le Lecce-Monteroni, 73100 Lecce, Italy.

ABSTRACT

Hydrozoa of the Mediterranean Sea are well known and a recent monograph covers 457 species. Mediterranean non-Siphonophoran Hydrozoa comprises 398 species, an increasing number due to continuous updates, representing about 10 % of the 3,702 currently valid species reported in a recent world assessment of hydrozoan diversity. Many new records are non indigenous species, previously described species that occurred elsewhere and whose arrival was presumably caused by human activities. However, many species reported in the past are not recorded in recent times. Realistic assessments of species pools require addition of new species, but also subtraction of species not found since a certain period. With the confidence of extinction index, cases of putative extinction can be raised. Out of the 398 known species, only 162 (41 %) have been reported in the last decade, while 53 (13 %) are not recorded in the literature since at least 41 years. According to the confidence of extinction index, 60 % of the 53 missing species are extinct, and 11 % are putatively extinct from the basin. From a biogeographical point of view, the missing species are: 34 % endemic, 19 % boreal, 15 % Mediterranean-Atlantic, 11 % Indo-Pacific, 11 % circumtropical, 4 % cosmopolitan, 2 % tropical-Atlantic, 4 % non-classifiable. Fluctuations in species composition into a certain area cause heavy variability in the expression of both structural and functional biodiversity. As consequence, the regional biodiversity should be analyzed through its temporal evolution, to detect changes and their possible causes. This approach has profound consequences on biodiversity assessments and also on the compilation of red lists.

No MeSH data available.


Related in: MedlinePlus