Faunal Heterogeneity Research Articles

Biodiversity, biogeography, and connectivity of polychaetes in the world's largest marine minerals exploration frontier

AbstractAimThe abyssal Clarion‐Clipperton Zone (CCZ), Pacific Ocean, is an area of commercial importance owing to the growing interest in mining high‐grade polymetallic nodules at the seafloor for battery metals. Research into the spatial patterns of faunal diversity, composition, and population connectivity is needed to better understand the ecological impacts of potential resource extraction. Here, a DNA taxonomy approach is used to investigate regional‐scale patterns of taxonomic and phylogenetic alpha and beta diversity, and genetic connectivity, of the dominant macrofaunal group (annelids) across a 6 million km2 region of the abyssal seafloor.LocationThe abyssal seafloor (3932–5055 m depth) of the Clarion‐Clipperton Zone, equatorial Pacific Ocean.MethodsWe used a combination of new and published barcode data to study 1866 polychaete specimens using molecular species delimitation. Both phylogenetic and taxonomic alpha and beta diversity metrics were used to analyse spatial patterns of biodiversity. Connectivity analyses were based on haplotype distributions for a subset of the studied taxa.ResultsDNA taxonomy identified 291–314 polychaete species from the COI and 16S datasets respectively. Taxonomic and phylogenetic beta diversity between sites were relatively high and mostly explained by lineage turnover. Over half of pairwise comparisons were more phylogenetically distinct than expected based on their taxonomic diversity. Connectivity analyses in abundant, broadly distributed taxa suggest an absence of genetic structuring driven by geographical location.Main ConclusionsSpecies diversity in abyssal Pacific polychaetes is high relative to other deep‐sea regions. Results suggest that environmental filtering, where the environment selects against certain species, may play a significant role in regulating spatial patterns of biodiversity in the CCZ. A core group of widespread species have diverse haplotypes but are well connected over broad distances. Our data suggest that the high environmental and faunal heterogeneity of the CCZ should be considered in future policy decisions.

Does grab size influence sampled macrofauna composition? A test conducted on deep-sea communities in the northeast Atlantic

In deep-sea surveys, heavy gears are often preferred to effectively collect macro benthos while smaller samplers are sufficient in coastal and shallow areas. However, there are few comparative studies of the samples retained and results gained from different-sized grabs. To study the differences in sampling properties between a small (sampling area of 0.1 m2) and a large (0.25 m2) van Veen grab, 1 m2 of seafloor was sampled with each of the grab sizes at four test sites in the Barents- and Norwegian Sea; one inside a fjord and three offshore, across a depth range of 287–963 m. Overall, the small and large grab collected a comparable number of species and individuals: 248 and 233 species, and 6074 and 6143 individuals, respectively. The large grab retrieved the most species at the deepest location while the small grab collected more species at the other test sites. Based on internationally recommended 0.5 m2 sampling units, a variation in the total species richness per test site of 7–13% was found while the diversity indices (ES100 and H′) varied by less than 10%. Independent of grab size, a cluster and nMDS analysis showed four clearly separated sample-groups that correspond to the four test stations although the multivariate dispersion was consistently higher for the small grab. A SIMPROF test showed no grab size-dependent differences. ANOSIM and PERMANOVA tests showed differences between grab sizes for the deepest station, where a similar difference occurred also between samples of the same grab size. This station displayed the least faunal heterogeneity, indicating that faunal patchiness may influence any grab-size differences. The results indicate that the two van Veen grabs tested deliver comparable quantitative faunal compositions. For the small grab, however, numerous samples were rejected due to poor performance, resulting in increased sampling time, ship costs and a suggested biased sampling towards less heterogeneous sediments at the fjord site.

Impacts of spatial and environmental differentiation on early Palaeozoic marine biodiversity.

The unprecedented diversifications in the fossil record of the early Palaeozoic (541-419 million years ago) increased both within-sample (α) and global (γ) diversity, generating considerable ecological complexity. Faunal difference (β diversity), including spatial heterogeneity, is thought to have played a major role in early Palaeozoic marine diversification, although α diversity is the major determinant of γ diversity through the Phanerozoic. Drivers for this Phanerozoic shift from β to α diversity are not yet resolved. Here, we evaluate the impacts of environmental and faunal heterogeneity on diversity patterns using a global spatial grid. We present early Palaeozoic genus-level α, β and γ diversity curves for molluscs, brachiopods, trilobites and echinoderms and compare them with measures of spatial lithological heterogeneity, which is our proxy for environmental heterogeneity. We find that α and β diversity are associated with increased lithological heterogeneity, and that β diversity declines over time while α increases. We suggest that the enhanced dispersal of marine taxa from the Middle Ordovician onwards facilitated increases in α diversity by encouraging the occupation of narrow niches and increasing the prevalence of transient species, simultaneously reducing spatial β diversity. This may have contributed to a shift from β to α diversity as the major determinant of γ diversity increase over this critical evolutionary interval.

The oldest abelisaurid record from Brazil and the palaeobiogeographic significance of mid-Cretaceous dinosaur assemblages from northern South America

Knowledge on the faunal record from the mid-Cretaceous of northern South America has come mainly from the Araripe Basin, northeastern Brazil. However, the Cenomanian Alcântara Formation of the São Luís-Grajaú Basin has recently increased in paleontological importance. Regarding their non-avian dinosaur diversity, the formation has yielded body and trace fossils of spinosaurid, carcharodontosaurid, noasaurid, and maniraptoran theropods, rebbachisaurid and titanosaur sauropods, and possible ornithopods. Here, we report the first unequivocal record of an abelisaurid theropod from the Alcântara Formation, consisting of two shed tooth crowns from the Baronesa Beach locality. They are the oldest occurrence of Abelisauridae from Brazil. With this new record, the non-avian dinosaur assemblage from the Alcântara Formation is most similar to that of the Kem Kem Beds, as suggested by previous works and supported here by similarity analyses of mid-Cretaceous dinosaur-bearing units. Our results also indicate a faunal heterogeneity within northern South America, previously overlooked by studies of this whole landmass as a single sampling unit. We also suggest future approaches treat the dinosaur assemblage from each fossil site or formation as a particular sample unit instead of combining geographically and temporally distinct records.

Heterogeneity of conodont faunas in the Cache Creek Terrane, Canada; significance for tectonic reconstructions of the North American Cordillera

The oceanic Cache Creek Terrane has long been interpreted to be exotic relative to the neighbouring Stikine and Quesnel terranes, on the basis of its unusual fossil faunas. Current tectonic models for the amalgamation of these three terranes have to account for the position of the exotic Cache Creek Terrane between two volcanic island arc terranes, and competing models invoke either terrane entrapment or strike-slip motion to explain this configuration. Although previous paleobiogeographic studies have attempted to assess the degree of faunal variability among terranes of the North American Cordillera, none have yet measured the amount of internal faunal heterogeneity and considered the effect that this may have on tectonic reconstructions. The use of multivariate statistics demonstrates that the Late Paleozoic to Triassic conodont faunas from the Cache Creek Terrane show distinct heterogeneity. The degree of heterogeneity among faunas from different regions of the terrane varies with time, and does not correlate with temporal changes in depositional environment, conodont ecology, or species endemism. Instead, it is proposed that the Cache Creek Terrane may consist of a number of sub-terranes which moved independently of each other prior to the final accretion of the Intermontane terranes. Periods of low faunal heterogeneity may correspond to times when the sub-terranes were close together, whereas periods of high heterogeneity may indicate that the sub-terranes had moved further apart. This interpretation requires that tectonic models for the formation of this part of the Cordillera emphasise lateral movement both within and between terranes prior to accretion.

Developing policy-relevant river fish monitoring in Greece: Insights from a nation-wide survey

A wide-ranging river fish survey was executed in the summer of 2009 as part of the preparatory actions for the establishment of a monitoring programme for the EU Water Framework Directive (WFD). This was the first extensive electrofishing campaign for WFD standardized bioassessment in Greece and the experience and insights gained are used here to provide a review of fish-based assessment conditions and requirements in this country. The survey sampled 85 sites on 25 rivers throughout mainland Greece, collecting 70 species of freshwater fish. Quantitative site-based assemblage data is used for taxonomic and ordination analyses revealing a strong biogeographic regionalization in the distribution of the ichthyofauna. The structural and spatial organisation of the fish fauna through the use of species-level and community-level data analyses is explored in three ecoregions where data was deemed sufficient. Transitions in community taxonomic composition among ecoregions were abrupt and concordant with geographical barriers and reflect the influence of historical biogeographic processes. Community-based analysis revealed a substantial degree of variation in quantitative attributes of the fish assemblages among ecoregions. Key conclusions of this work are: (a) the fish-based bioassessment system must be regionalised to reflect biogeographic variation, (b) high faunal heterogeneity among ecoregions (taxonomic, structural), and to a lower degree among basins, constrain the transferability of bioassessment metrics and indices created for explicit regions to other regional frameworks; (c) faunal depauperation in most of the study areas reduce the utility of functional bioassessment metrics and also limits the utilization of rare species and the applicability of the classical form of the “Index of Biotic Integrity” concept. Recommendations to cope with these problems are discussed.

The mammals of Mt. Amuyao: a richly endemic fauna in the Central Cordillera of northern Luzon Island, Philippines

AbstractFaunas of old oceanic islands often have extremely high levels of endemism and are considered highly susceptible to anthropogenic disruption. We surveyed the richly endemic small mammal fauna on Mt. Amuyao in the Central Cordillera of northern Luzon Island, Philippines. We tested hypotheses regarding elevational patterns of species richness and community composition, community response to habitat disturbance, and interactions of native and non-native mammals. Our study revealed greater species richness and faunal heterogeneity within the Central Cordillera than previously suspected. We documented 15 native species (14 rodents and 1 insectivore), and two species of non-native rodents. All of the native species are endemic to the Philippines, eight being restricted to the Cordillera. Twelve of the 14 native rodents belong to two ancient endemic clades, indicating that most of the regional diversity is the product of

Taphonomy and morphology of the Ediacara form genus Aspidella

Aspidella, the disk-like Ediacaran form genus, is a common and globally distributed member of the Ediacara Biota. In South Australia, it occurs prolifically (n>1000) in locally dense assemblages on the bases of sandstone beds in the eponymous Ediacara Member of the Rawnsley Quartzite. Association with stalks, fronds and textured organic surfaces (TOS) has led to the interpretation of Aspidella as the holdfast of a frondose, Charniodiscus-like organism which lived with its holdfast secured within or under a sandy microbial mat and its stalk and frond protruding above the substrate and into the water column. As the dominant component of four fossiliferous beds and a minor component of most others, Aspidella exemplifies the bed-scale faunal heterogeneity characteristic of Ediacara fossil assemblages. Aspidella itself, moreover, is characterized by strong morphological variability, including variation in the presence or absence of particular distinct morphological features, variable preservation as internal and external molds, variable relief and a broad size range. However, the distribution of morphological characters is unrelated to either Aspidella specimen size or bed assemblage composition. Herein we demonstrate that this morphological diversity is an expression of neither ontogenetic nor species-level anatomical differences, but rather is the product of differential taphonomy related to variation in local substrate-related sedimentological and biogenic factors, particularly the presence or absence of TOS composed of the eukaryotic tubular organism Funisia.

Disentangling the effects of geographic distance and environmental dissimilarity on global patterns of species turnover

ABSTRACTAim To distinguish the effects of geographic distance and environmental dissimilarity on global patterns of species turnover in four classes of terrestrial vertebrates (mammals, birds, reptiles and amphibians).Location Six hundred and sixty terrestrial ecoregions across the globe.Methods We calculated species turnover between each pair of ecoregions, using the Jaccard index (J). We selected seven variables to quantify environment in each ecoregion, and subjected the environmental values to a principal components analysis. For each realm, we applied multiple regression analysis relating the natural logarithm of the Jaccard index (lnJ) to geographic distance alone and in combination with differences in the environment variables measured as principal components (PC). We used partial correlations to partition variance in lnJ between unique contributions of distance and environmental PC scores, the covariation between distance and environment, and unexplained variance. To examine the latitude and species turnover relationship, we regressed lnJ on latitude with distance between ecoregions being included as a covariate.Results The natural logarithm of the Jaccard index (lnJ) decreased significantly with increasing geographic distance for all vertebrate classes in each zoogeographic realm, and the slopes of the relationships per 1000 km ranged from −0.251 to −1.043. With environmental differences included in the analysis, both geographic distance and environmental differences were substantial predictors of lnJ for every combination of taxon and realm. On average, the unique contribution of geographic distance to variation in species turnover between ecoregions was about 1.4 times that of the environmental differences between ecoregions. Species turnover generally decreased with increasing latitude when controlling for geographic distance. The value of lnJ for each vertebrate class was highly and positively correlated with those of the other vertebrate classes.Main conclusions Our analyses suggest that both dispersal‐based and niche‐based processes have played important roles in determining faunal similarities among vertebrate assemblages at the spatial scale examined. Furthermore, reptiles and amphibians exhibited greater distance‐independent faunal heterogeneity among ecoregions and greater turnover among ecoregions with respect to geographic and environmental distance than birds and mammals.

Small mammals of Chapada dos Veadeiros National Park (Cerrado of Central Brazil): ecologic, karyologic, and taxonomic considerations

This work is based on a survey of small mammals carried out in the Chapada dos Veadeiros National Park, a natural reserve located in the mountains of the Planalto Central Goiano in the Cerrado of Central Brazil. The 227 specimens collected represented six marsupial and 13 rodent species. Taxonomic, karyologic, and ecologic considerations are present and discussed in the present work. Our data reflected the faunal heterogeneity with respect to both elevation and vegetation because only eight of the 19 species were collected at both high and low elevations. The composition of the small mammal fauna of the park is influenced by predominance of forest formations at low elevations and cerrado with rupestrian areas at high elevations. Presence of endemic species and one undescribed demonstrated that the cerrado has an endemic fauna and a little known diversity of small mammals.

Recovery in Antarctic benthos after iceberg disturbance: trends in benthic composition, abundance and growth forms

The response of an Antarctic benthic community to iceberg disturbance was investi- gated using underwater photographs (1 m 2 each) on the SE Weddell Sea shelf. This study: (1) char- acterises composition, coverage, number of patches and area of sessile benthic fauna, (2) describes faunal heterogeneity using MDS ordination and identifies 'structural taxa' of each recovery stage, and (3) analyses changes of growth-form patterns during Antarctic recovery. We observed changes in the space occupation of benthic organisms along the recolonisation stages. Uncovered sediment characterised the early stages ranging from 98 to 91% of the coverage. The later stages showed high (70.5%) and intermediate (52.5%) values of benthic coverage, where demosponges, bryozoans and ascidians exhibited a high number of patches and taxa. Several 'structural species' were identified among the stages, and information is provided on their coverage, number of patches and area. Over- all, maximum areas of patches increased as recovery proceeded. Early stages were characterised by the presence of pioneer taxa, which only partly covered the bottom sediment but were locally abun- dant (e.g. the bryozoan Cellarinella spp. and the gorgonian Primnosis antarctica with a maximum coverage of 13 and 3%, and 51 and 30 patches m -2 , respectively). Soft bush-like bryozoans, sheet-like sabellid polychaetes, and tree-like sponges, gorgonians, bryozoans and ascidians were the first colonisers. Mound-like sponges and ascidians as well as tree-like organisms with a long lifespan and different reproductive strategies defined the late stages. We conclude by comparing the selected 'structural species' and relating their life-history traits to differences in distribution in the course of Antarctic recovery.

Macrobenthic community structure within and beneath the oxygen minimum zone, NW Arabian Sea

Investigations of macrobenthos were carried out within and beneath the oxygen minimum zone (OMZ, <0.5 ml l −1) during Fall 1994 on the Oman margin, NW Arabian Sea. Six stations (400, 700, 850, 1000, 1250 and 3400 m) were characterized with respect to macrofaunal abundance, biomass, body size, taxonomic composition, diversity and lifestyles, and the relation of these parameters to environmental conditions. The OMZ (400–1000 m) was dominated by a dense (5818–19,183 ind m −2), soft-bodied assemblage consisting largely (86–99%) of surface-feeding polychaetes. Spionids and cirratulids dominated at the 400- and 700-m stations, paraonids and ampharetids at the 850- and 1000-m stations. Molluscs and most crustaceans were common only below the OMZ (⩾1250 m); a species of the amphipod Ampelisca was abundant within the OMZ, however. Both density and biomass were elevated within the OMZ relative to stations below but body size did not differ significantly among stations. The lower OMZ boundary (0.5 ml l −1) was not a zone of enhanced macrofaunal standing stock, as originally hypothesized. However, abundance maxima at 700–850 m may reflect an oxygen threshold (0.15–0.20 ml l −1) above which macrofauna take advantage of organically enriched sediments. Incidence of burrowing and subsurface-deposit feeding increased below the OMZ. Species richness ( E[ S 100]), diversity ( H′) and evenness ( J′) were lower and dominance (R1D) was higher within than beneath the OMZ. Within-station (between-boxcore) faunal heterogeneity increased markedly below the OMZ. Surface sediment pigment concentrations and oxygen together explained 96–99% of the variance in measures of E[S 100], H′ and J′ across the transect; grain size and % TOC did not yield significant regressions. Pigments, assumed to reflect food availability and possibly oxygen effects on organic matter preservation, were negatively correlated with species richness and evenness, and positively correlated with dominance. The reverse was true for water depth. Macrobenthic patterns of calcification and lifestyle within the Oman margin OMZ (0.13–0.3 ml l −1) match the dysaerobic biofacies of paleo-environmental reconstruction models.

Spatial variation in non-target effects of the insecticides chlorpyrifos, cypermethrin and pirimicarb on Collembola in winter wheat

Contiguous winter wheat fields of similar cropping history and soil type were used in a study of the responses of Collembola to summer sprays of cypermethrin and pirimicarb in southern England. Chlorpyrifos was included in the study as a toxic standard. Epigeic arthropods were captured by suction sampling and crop-inhabiting species obtained by dissecting wheat ears. Eight genera of Collembola responded significantly to the insecticide treatments. Collembolan abundance decreased after chlorpyrifos was applied but increased after use of cypermethrin. Negative effects of cypermethrin and pirimicarb on Collembola were not detected in this study. Effects of chlorpyrifos varied spatially as a result of faunal heterogeneity among the fields, despite apparent homogeneity of the site. Some species known to be susceptible to chlorpyrifos were absent from one or more of the fields. The implications of these findings for the interpretation of non-target pesticide effects and the potential use of Collembola as bioindicators in field studies with pesticides are discussed. © 1999 Society of Chemical Industry

Spatial Response of Mammals to Late Quaternary Environmental Fluctuations

Analyses of fossil mammal faunas from 2945 localities in the United States demonstrate that the geographic ranges of individual species shifted at different times, in different directions, and at different rates in response to late Quaternary environmental fluctuations. The geographic pattern of faunal provinces was similar for the late Pleistocene and late Holocene, but differing environmental gradients resulted in dissimilar species composition for these biogeographic regions. Modern community patterns emerged only in the last few thousand years, and many late Pleistocene communities do not have modern analogs. Faunal heterogeneity was greater in the late Pleistocene.