Large scale patterns and trophic structure of southern African rocky shores: the roles of geographic variation and wave exposure

In this study we revise the biogeographic delimitation, and large-scale patterns of community structure of the intertidal rocky shores of southern Africa. We use binary (presence/absence) and per-species biomass data collected at fifteen localities and thirty-seven different rocky sites, encompassing the shores of southern Namibia, South Africa and southern Mozambique. Multivariate analyses revealed that the shores of southern Africa (south of 25°) can be divided into three main biogeographic provinces: the west coast or Namaqua province, the south coast or Agulhas province and the east coast or Natal province. The biomass structure of the intertidal rocky shores communities of southern Africa varied at a large scale, corresponding to biogeographic differences, while local-scale variation accorded with the intensity of local wave action. The average biomass of west coast communities was on average significantly greater than that of the south and east provinces. At a local scale, the community biomass on exposed shores was an order of magnitude greater than on sheltered shores, within all biogeographic provinces. Semi-exposed shores exhibited intermediate average biomass. The trophic structure of these communities varied significantly with wave action: autotrophs, filter-feeders and invertebrate predators were more prevalent on wave exposed than sheltered shores, whereas grazers were more abundant on sheltered and semi-exposed shores. Exposed shores were consistently dominated by far fewer species than semi-exposed and sheltered shores, independently of biogeographic differences. Within all biogeographic provinces semi-exposed and sheltered shores were more diverse than exposed shores. West coast intertidal communities therefore had high levels of biomass, but were consistently species-poor. Several working hypotheses that could explain these large and small-scale patterns are presented.     

Patterns of distribution for southern Australian marine echinoderms and decapods

Aim To relate patterns of distribution of marine echinoderms and decapods around southern Australia to major ecological and historical factors. Location Shallow‐water (0–100 m) marine waters off southern Australia, south of 30° S. Methods (1) Record the presence/absence of known echinoderm and decapod species in cells of c. 1° latitude and longitude, along the coast of southern mainland Australia and Tasmania. (2) Describe patterns in species composition, species richness and endemism through gradient analysis, ordination and cluster analysis. (3) Relate these patterns to distance and temperature gradients, the area of continental shelf, the average size of species range, and known historical factors. Results Species composition varied with both latitude and longitude. Species richness was relatively constant from east to west but graded with latitude from high in the warm‐temperate regions around Perth and Sydney to low in cool‐temperate southern Tasmania. Species richness was not related to the area of continental shelf or average species range size. Species turnover was not correlated with rates of temperature change. It was problematic to separate distance from temperature gradients, but there was evidence that the southern distribution limits of some species are related to minimum sea surface temperature. Within the taxonomic groups surveyed, evolutionary radiation has been largely limited to a few cosmopolitan species‐rich genera. Main conclusions There are historical as well as ecological hypotheses explaining the latitudinal gradient of marine species richness in southern Australia: (1) the continual invasion and speciation of species of tropical origin as Australia has split from Gondwana and drifted northward; (2) progressive extinction of some Gondwanan cool‐temperate species at the limits of their range; (3) low level of immigration of additional cool‐temperate species; and (4) some in situ endemic speciation.     

Input data, analytical methods and biogeography of Elegia (Restionaceae)

Aim The aim of this paper is to determine the optimal methods for delimiting areas of endemism for Elegia L. (Restionaceae), an endemic genus of the Cape Floristic Region. We assess two methods of scoring the data (presence–absence in regular grids, or in irregular eco‐geographical regions) and three methods for locating biogeographical centres or areas of endemism, and evaluate one method for locating biotic elements. Location The Cape Floristic Region (CFR), South Africa. Methods The distribution of all 48 species of Elegia was mapped as presence–absence data on a quarter‐degree grid and on broad habitat units (eco‐geographical areas). Three methods to delimit areas of endemism were applied: parsimony analysis of endemism (PAE), phenetic cluster analysis, and NDM (‘end em ism’). In addition, we used presence–absence clustering (‘Prabclus’) to delimit biotic elements. The performances of these methods in elucidating the geographical patterns in Elegia were compared, for both types of input data, by evaluating their efficacy in maximizing the proportion of endemics and the number of areas of endemism. Results Eco‐geographical areas perform better than quarter‐degree grids. The eco‐geographical areas are potentially more likely to track the distribution of species. The phenetic approach performed best in terms of its ability to delimit areas of endemism in the study area. The species richness and the richness of range‐restricted species are each highest in the south‐western part of the CFR, decreasing to the north and east. The phytogeographical centres identified in the present study are the northern mountains, the southern mountains (inclusive of the Riviersonderend Mountains and the Cape Peninsula), the Langeberg range, the south coast, the Cape flats, and the west coast. Main conclusions This study demonstrates that (1) eco‐geographical areas should be preferred over a grid overlay in the study of biogeographical patterns, (2) phenetic clustering is the most suitable analytical method for finding areas of endemism, and (3) delimiting biotic elements does not contribute to an understanding of the biogeographical pattern in Elegia. The areas of endemism in Elegia are largely similar to those described in other studies, but there are many detailed differences.     

Oceanographic Conditions Limit the Spread of a Marine Invader along Southern African Shores

Invasive species can affect the function and structure of natural ecological communities, hence understanding and predicting their potential for spreading is a major ecological challenge. Once established in a new region, the spread of invasive species is largely controlled by their dispersal capacity, local environmental conditions and species interactions. The mussel Mytilus galloprovincialis is native to the Mediterranean and is the most successful marine invader in southern Africa. Its distribution there has expanded rapidly and extensively since the 1970s, however, over the last decade its spread has ceased. In this study, we coupled broad scale field surveys, Ecological Niche Modelling (ENM) and Lagrangian Particle Simulations (LPS) to assess the current invaded distribution of M. galloprovincialis in southern Africa and to evaluate what prevents further spread of this species. Results showed that all environmentally suitable habitats in southern Africa have been occupied by the species. This includes rocky shores between Rocky Point in Namibia and East London in South Africa (approx. 2800 km) and these limits coincide with the steep transitions between cool-temperate and subtropical-warmer climates, on both west and southeast African coasts. On the west coast, simulations of drifting larvae almost entirely followed the northward and offshore direction of the Benguela current, creating a clear dispersal barrier by advecting larvae away from the coast. On the southeast coast, nearshore currents give larvae the potential to move eastwards, against the prevalent Agulhas current and beyond the present distributional limit, however environmental conditions prevent the establishment of the species. The transition between the cooler and warmer water regimes is therefore the main factor limiting the northern spread on the southeast coast; however, biotic interactions with native fauna may also play an important role.     

Marine macroalgal biodiversity hotspots: why is there high species richness and endemism in southern Australian marine benthic flora?

The southern Australian marine macroalgal flora has the highest levels of species richness and endemism of any regional macroalgal flora in the world. Analyses of species composition and distributions for the southern Australian flora have identified four different floristic elements, namely the southern Australian endemic element, the widely distributed temperate element, the tropical element and a cold water element. Within the southern Australian endemic element, four species distribution patterns are apparent, thought to largely result from the Jurassic to Oligocene fragmentation of East Gondwana, the subsequent migration of Tethyan ancestors from the west Australian coast and the later invasion of high latitude Pacific species. Climatic deterioration from the late Eocene to the present is thought responsible for the replacement of the previous tropical south coast flora by an endemic temperate flora which has subsequently diversified in response to fluctuating environmental conditions, abundant rocky substrata and substantial habitat heterogeneity. High levels of endemism are attributed to Australia's long isolation and maintained, as is the high species richness, by the lack of recent mass extinction events. The warm water Leeuwin Current has had profound influence in the region since the Eocene, flowing to disperse macroalgal species onto the south coast as well as ameliorating the local environment. It is now evident that the high species richness and endemism we now observe in the southern Australian marine macroalgal flora can be attributed to a complex interaction of biogeographical, ecological and phylogenetic processes over the last 160 million years.     

Climatic and biogeographical associations of southern African dung beetles (Coleoptera: Scarabaeidae s. str.)

Climatic and biogeographical associations of southern African dung beetles (Scarabaeinae, Coprinae) were analysed from a collection amassed between 1971 and 1986. Endemism to Africa south of 15°S was much greater in southwesterly climates (winter rainfall, bimodal spring/autumn rainfall, arid late summer rainfall) than to the north‐east in the moist, mid‐summer rainfall region. Major biogeographical groups centred to the south‐west comprised predominantly southern African endemics, Western/Eastern Cape coast, Karoo, Karoo/Namib, northern Namibia and the south‐western Kalahari. Biogeographical groups centred on the south‐eastern highlands and the subtropical east coast (mid‐summer rainfall) also comprised predominantly southern African endemics. All other major groups centred to the north‐east in the mid‐summer rainfall region comprised predominantly species with widespread tropical biogeographical affiliations, pan‐southern Africa but centred in the east, pan‐mid‐summer rainfall region, eastern mid‐summer rainfall region, tropical east Zimbabwe/central Moçambique, subtropical/tropical game reserves (non‐ruminant dung specialists). There were cross‐climatic differences in taxonomic composition of the fauna. Within the winter rainfall region, percentage species composition of Scarabaeinae was greater whereas that of the coprine tribe, Onthophagini, was lower than within the other three climatic regions. Percentage species richness of most other tribes of Coprinae differed little between most climates but that of Scarabaeinae declined from west to east (Canthonini, Scarabaeini), east to west (Sisyphini) or to either side of the late summer rainfall region (Gymnopleurini).     

Species richness and diversity in different functional groups across environmental stress gradients: a model for marine rocky shores

We present a model predicting how the species richness and diversity within benthic functional groups should vary across the full environmental stress gradient across which a regional biota from marine rocky shores can occur. Built upon previous models, our model makes predictions for sessile species (macroalgae and filter feeders), herbivores, and carnivores. We tested some of its predictions by surveying vertical (intertidal elevation) and horizontal (wave exposure and ice scour) stress gradients in northern Nova Scotia, Canada. Because of harsh winter conditions, these coasts only depict approximately intermediate‐to‐high yearly levels of stress that the cold‐temperate, rocky intertidal biota from the northwestern Atlantic can experience. The observed trends matched predictions for sessile species in 75% of the studied gradients, and showed a moderate agreement for herbivores and carnivores only when they were combined as mobile consumers. Agreement meant that both richness and diversity increased from the most stressful to the most benign habitats that can be found in northern Nova Scotia. Also as predicted, sessile species generally showed a faster rate of increase in richness than mobile consumers. Our model also predicted a higher overall richness for sessile species than for mobile consumers, which was true by a factor of 3. Therefore, our model may constitute a useful tool to understanding community composition as a function of abiotic stress, which may in turn facilitate studies on community functioning. Model predictions for lower stress ranges could be tested on more southern shores where the same regional biota occurs.     

Biogeographical patterns of rocky intertidal communities along the Pacific coast of North America

Aim Our aim in this paper is to present the first broad‐scale quantification of species abundance for rocky intertidal communities along the Pacific coast of North America. Here we examine the community‐level marine biogeographical patterns in the context of formerly described biogeographical regions, and we evaluate the combined effects of geographical distance and environmental conditions on patterns of species similarity across this region. Location Pacific coast of North America. Methods Data on the percentage cover of benthic marine organisms were collected at 67 rocky intertidal sites from south‐eastern Alaska, USA, to central Baja California Sur, Mexico. Cluster analysis and non‐metric multidimensional scaling were used to evaluate the spatial patterns of species similarity among sites relative to those of previously defined biogeographical regions. Matrices of similarity in species composition among all sites were computed and analysed with respect to geographical distance and long‐term mean sea surface temperature (SST) as a measure of environmental conditions. Results We found a high degree of spatial structure in the similarity of intertidal communities along the coast. Cluster analysis identified 13 major community structure ‘groups’. Although breaks between clusters of sites generally occurred at major biogeographical boundaries, some of the larger biogeographical regions contained several clusters of sites that did not group according to spatial position or identifiable coastal features. Additionally, there were several outliers – sites that grouped alone or with sites outside their region – for which localized features may play an important role in driving community structure. Patterns of species similarity at the large scale were highly correlated with geographical distance among sites and with SST. Importantly, we found community similarity to be highly correlated with long‐term mean SST while controlling for the effects of geographical distance. Main conclusions These findings reveal a high degree of spatial structure in the similarity of rocky intertidal communities of the north‐east Pacific, and are generally consistent with those of previously described biogeographical regions, with some notable differences. Breaks in similarity among clusters are generally coincident with known biogeographical and oceanographic discontinuities. The strong correlations between species similarity and both geographical position and SST suggest that both geography and oceanographic conditions have a large influence on patterns of intertidal community structure along the Pacific coast of North America.     

Biogeography of the octocorallian coelenterate fauna of southern Africa

The geographical and bathymetric distribution of southern African octocorals is analysed. Of the over 200 estimated species of regional octocorals, 81 confirmed and adequately described species are studied using a radial sector method. Two primary faunal components are recognized–endemic (53.3% of the fauna by numbers of species) and Indo-Pacific (39.4%). An Atlantic component contributes only minimally (about 1.7%), while the remaining fauna is made up of cosmopolites (2.8%) and scattered species (2.8%). A subantarctic component is not evident for the present-day, although evidence for previous contact is presented. A sister-group analysis using genera as a guide to sister species, shows the biogeographic affinities for the present-day fauna as a whole to be 45% Indo-Pacific, 31% cosmopolitan, 10% endemic, 10% Atlantic and 4% southern oceans (subantarctic). Applying the same method to only those genera with endemic species shows the affinities of the present-day endemic fauna to be 27.5% Indo-Pacific, 27.5% endemic, 24% cosmopolitan, 14% Atlantic and 7% subantarctic. Clearly defined boundaries for west, south, and east coast faunas (as recognized by previous authors in describing various intertidal faunas) are found not be present with regard to the octocoral fauna (largely due to its overwhelmingly subtidal nature). Instead two primary zoogeographic provinces are recognized–the Cape Endemic Province (extending from Liideritz to Inhaca Island) and the south-western fringe of the Indo-Pacific Province from East London north-eastwards. An overlap zone between these two is recognized between East London and Inhaca Island, with the region in the vicinity of Richards Bay having an essentially evenly mixed fauna (roughly 50% Cape Endemic Province and 50% Indo-Pacific). Of the 84 octocoral genera recorded for the region, seven (or 8.3%) are endemic, and of these, five are monotypic while two are ditypic. The fauna is shown to be predominantly sublittoral (about 95% by numbers of species), the shallow sublittoral (< 100 m in depth) being the region with highest species richness. Pennatulaceans are eurybathic (intertidal to 4756 m) and clearly show a high proportion of cosmopolites (20% of presently identified species). Soft corals are stenobathic and restricted to the intertidal, continental shelf and uppermost portion of the continental slope (<500m), while gorgonians are intermediate in depth distributon (intertidal to 1200 m). No cosmopolitan alcyonaceans are presently recorded. The centre of the Cape Endemic Province is the Agulhas Bank–an extensive region of shallow continential shelf (< 200 m in depth) between Cape Town and East London. Two regions of octocoral radiation for southern Africa are postulated–the Agulhas Bank and the western Indian Ocean.     

Revealing the scale of marine bioinvasions in developing regions: a South African re-assessment

As recently as 2009 the number of introductions recorded for South Africa comprised 22 marine and estuarine species. This review aims to reassess the diversity and scale of introduced marine and estuarine species in the region. Accurate taxonomic and systematic work, broad review of historical records and new sampling surveys across selected marine habitats conducted by a team of local and international experts has effectively revealed the presence of previously misidentified, overlooked, or new introductions. A total of 86 introduced and 39 cryptogenic species are recognized, increasing known numbers four and twofold respectively within 1 year, although the current assessment is far from fully comprehensive. Additional species were revealed within the historic literature (76%), from surveys conducted post-2005 (11%) and following taxonomic resolution (13%). Temporal analyses confirmed discovery rates were increasing over time. Ship fouling and ballast water were the dominant vector pathways, accounting for 48 and 38% respectively. Spatial analyses revealed patterns of bioinvasion to be significantly higher on the west coast compared to the other coastal regions. Overall, 53% of introductions were concentrated within harbour areas with only 4 open-coast invaders detected at present. Introduced species found in the cool and warm-temperate provinces of the west and south coast mainly originated from the northern hemisphere (65%). In contrast, introductions located in the sub-tropical and tropical provinces of the east coast mainly originated from the southern hemisphere (18%), with the remaining 17% of introduced species being of unknown origin. The research approach described has proven pivotal, contributing massively toward revealing the true scale and patterns of bioinvasion for a developing region within a relatively short period of time.     

Triton's trident: cryptic Neogene divergences in a marine clam (Lasaea australis) correspond to Australia's three temperate biogeographic provinces

The southern coast of Australia is composed of three distinct biogeographic provinces distinguished primarily by intertidal community composition. Several ecological mechanisms have been proposed to explain their formation and persistence, but no consensus has been reached. The marine clam Lasaea australis is arguably the most common bivalve on southern Australian rocky shores and occurs in all three provinces. Here, we tested if this species exhibits cryptic genetic structuring corresponding to the provinces and if so, what mechanisms potentially drove its divergence. Variation in two mitochondrial genes (16S and COIII) and one nuclear gene (ITS2) was assayed to test for genetic structuring and to reconstruct the clam's phylogenetic history. Our results showed that L. australis is comprised of three cryptic mitochondrial clades, each corresponding almost perfectly to one of the three biogeographic provinces. Divergence time estimates place their cladogenesis in the Neogene. The trident‐like topology and Neogene time frame of L. australis cladogenesis are incongruent with Quaternary vicariance predictions: a two‐clade topology produced by Pleistocene Bass Strait land bridge formation. We hypothesize that the interaction of the Middle Miocene Climate Transition with the specific geography of the southern coastline of Australia was the primary cladogenic driver in this clam lineage. Additional in‐depth studies of the endemic southern Australian marine biota across all three provinces are needed to establish the generality of this proposed older framework for regional cladogenesis.     

An environmental stress model correctly predicts unimodal trends in overall species richness and diversity along intertidal elevation gradients

Environmental stress is a major factor structuring communities. An environmental stress model (ESM) predicts that overall species richness and diversity should follow a unimodal trend along the full stress gradient along which assemblages from a regional biota can occur (not to be confused with the intermediate disturbance hypothesis, which makes predictions only for basal species along an intermediate-to-high stress range). Past studies could only provide partial support for ESM predictions because of the limited stress range surveyed or a low sampling resolution. In this study, we measured overall species richness and diversity (considering all seaweeds and invertebrates) along the intertidal elevation gradient on two wave-sheltered rocky shores from Helgoland Island, on the NE Atlantic coast. In intertidal habitats, tides cause a pronounced gradient of increasing stress from low to high elevations. We surveyed up to nine contiguous elevation zones between the lowest intertidal elevation (low stress) and the high intertidal boundary (high stress). Nonlinear regression analyses revealed that overall species richness and diversity followed unimodal trends across elevations on the two studied shores. Therefore, our study suggests that the ESM might constitute a useful tool to predict local richness and diversity as a function of environmental stress. Performing tests on other systems (marine as well as terrestrial) should help to refine the model.     

The distribution of the ectoparasite fauna of Sebastes capensis from the southern hemisphere does not correspond with zoogeographical provinces of free-living marine animals

Aim We examined the ectoparasite fauna of Sebastes capensis over almost all its geographical distribution range (Chilean, Argentinean and South African coasts) to determine (1) whether the ectoparasites of this host show a zoogeographical pattern and, if so, (2) how this pattern is related to known zoogeographical patterns for free‐living organisms. Location Fish were captured from 20, 24, 30, 33, 36, 40, 45 and 52° S along the Chilean coast; 11° S on the Peruvian coast; 43° S on the Argentina coast; and 34° S on the South African coast. Methods From April to September 2003 and from April to August 2004, 626 fish were captured. The parasites were collected using standard parasitological techniques. At the component community level, zoogeographical distribution patterns were evaluated using cluster analysis. At the infra‐community level, patterns of similarity in parasite composition among localities were investigated with multivariate discriminant analyses. Results The ectoparasite fauna of S. capensis consists of six species distributed along the whole of the Chilean coast. Four other species are distributed only within the transitional zone between the northern warm temperate region (Peruvian faunistic province), extending from Peru to the northern Chilean coast up to c. 30° S, and the cold temperate region (Magellanic faunistic province). The component communities from latitudes 30 to 40° S showed higher ectoparasite species richness, while localities on the margins of the geographical range showed lower species richness. Cluster analysis indicated a grouping of localities consistent with the transitional zone. Argentina and South Africa always emerged as separate localities. Main conclusions The ectoparasite communities of S. capensis do not follow a distributional pattern concordant with the known biogeographical zones for invertebrates and/or fish along the south‐eastern Pacific. Therefore their ectoparasite fauna is not useful as a zoogeographical indicator, although it does allow us to distinguish the transitional zone of the south‐eastern Pacific. On a more extended geographical scale, it is possible to distinguish the ectoparasite communities of S. capensis in the south‐eastern Pacific (as a whole) from those of Argentina and South Africa.     

Scale-dependent patterns of macrofaunal distribution in soft-sediment intertidal habitats along a large-scale estuarine gradient

We investigated the pattern of distribution of intertidal soft-bottom fauna in streams and lagoons of the Uruguayan coast at three spatial scales. The Río de la Plata and the Atlantic Ocean produce on this coast a large-scale gradient in salinity, defining a freshwater (west), an estuarine (central) and a marine (east) region. Within each region, there are several streams and coastal lagoons (sites) that define a second scale of variability. A third scale is given by intertidal gradients within each site. Species richness and total abundance was low in the freshwater west region and high in the central and east regions. The community in the west region was characterized by the clam Curbicula fluminea; in the other regions, it was dominated mainly by the polychaete Heteromastus similis. The polychaete Nephtys fluviatilis was more abundant in the east region, while another polychaete, Laeonereis acuta, characterized the central region. Sediment fractions did not vary significantly at this scale. At the scale of the sites, species richness and total macrofaunal abundance were higher in coastal lagoons than in streams. Coarse sands were more common in coastal lagoons, while medium and fine sand characterized the sediment in streams. Within each site, species richness and total abundance increased towards the lower intertidal level; the macrofauna of the upper levels were a subsample of the fauna occurring at the lower levels. There was also a significantly lower proportion of fine sand at the upper level. At regional scales, the observed patterns may be indirectly or directly related to the gradient in salinity, through differential physiological tolerance to osmotic stress. At the scale of the sites, variability may be explained mainly by geomorphological and sedimentological differences between lagoons and streams. Variation among levels may be related to gradients in desiccation, colonization and predation.     

Biogeographical structure and affinities of the marine demersal ichthyofauna of Australia

Aim To investigate the biogeographical structure and affinities of the Australian marine demersal ichthyofauna at the scale of provinces and bathomes for the purposes of regional marine planning. Location Australia. Methods Patterns of distribution in the Australian fish fauna, at both intra‐regional and global scales, were examined using a science‐based, management framework dividing Australia’s marine biodiversity into 16 province‐level biogeographical units. Occurrences of 3734 species in eight depth‐stratified bathomes (from the coast to the mid‐continental slope) within each province were analysed to determine the structure and local affinities of their assemblages and their association with faunas of nearby regions and oceans basins. Results Strong geographic and depth‐related structure was evident. Fish assemblages in each province, and in each bathome of each province, were distinct, with the shelf‐break bathome more similar to the adjacent continental shelf bathome than to the upper slope bathome. Data based only on endemic species performed well as a surrogate of the entire dataset, yielding comparable patterns of similarity between provinces and bathomes. Tropical and temperate elements were better discriminated than elements of the Pacific and Indian oceans, with the central western province more similar to the tropical provinces (including those in the east), and the eastern province closer to southern temperate provinces. The fauna shares the closest regional affinities with those of the adjacent south‐west Pacific, western Pacific Rim, and elements of wide‐ranging Indo‐Pacific components. Elements unique to the Pacific and Indian oceans are poorly represented. Main conclusions The complex nature of Australia’s marine ichthyofauna is confirmed. A hierarchy of provinces and bathomes, used to ensure that Australia’s developing marine reserve network is both representative and comprehensive, is equally robust when based on all known Australian fish species or on only those species endemic to this continent. Latitude and depth are more important than oceanic influences on the composition of this fauna at these scales.     

Evolutionary processes,dispersal limitation and climatic history shape current diversity patterns of European dragonflies

We investigated the effects of contemporary and historical factors on the spatial variation of European dragonfly diversity. Specifically, we tested to what extent patterns of endemism and phylogenetic diversity of European dragonfly assemblages are structured by 1) phylogenetic conservatism of thermal adaptations and 2) differences in the ability of post‐glacial recolonization by species adapted to running waters (lotic) and still waters (lentic). We investigated patterns of dragonfly diversity using digital distribution maps and a phylogeny of 122 European dragonfly species, which we constructed by combining taxonomic and molecular data. We calculated total taxonomic distinctiveness and mean pairwise distances across 4192 50 × 50 km equal‐area grid cells as measures of phylogenetic diversity. We compared species richness with corrected weighted endemism and standardized effect sizes of mean pairwise distances or residuals of total taxonomic distinctiveness to identify areas with higher or lower phylogenetic diversity than expected by chance. Broken‐line regression was used to detect breakpoints in diversity–latitude relationships. Dragonfly species richness peaked in central Europe, whereas endemism and phylogenetic diversity decreased from warm areas in the south‐west to cold areas in the north‐east and with an increasing proportion of lentic species. Except for species richness, all measures of diversity were consistently higher in formerly unglaciated areas south of the 0°C isotherm during the Last Glacial Maximum than in formerly glaciated areas. These results indicate that the distributions of dragonfly species in Europe were shaped by both phylogenetic conservatism of thermal adaptations and differences between lentic and lotic species in the ability of post‐glacial recolonization/dispersal in concert with the climatic history of the continent. The complex diversity patterns of European dragonflies provide an example of how integrating climatic and evolutionary history with contemporary ecological data can improve our understanding of the processes driving the geographical variation of biological diversity.     

Biogeographical patterns in endoparasite communities of a marine fish (Sebastes capensis Gmelin) with extended range in the Southern Hemisphere

Aim The endoparasites of Sebastes capensis Gmelin are examined over most of its geographical range (coasts of Peru, Chile, Argentina and South Africa) to determine: (1) whether the endoparasite communities of this fish show zoogeographical patterns; and (2) if so, whether there are any relationships between spatial variations in the endoparasite fauna and known zoogeographical patterns for marine free‐living organisms (e.g. prey that are included in the life cycles of endoparasites). Location Fish were captured at nine localities along the Pacific coast of South America, from 11° S in the centre of the Peruvian coast, to 52° S in southern Chile, and also at two localities in the Atlantic Ocean, at 43° S in Argentina, and 34° S in South Africa. Methods From April to September 2003 and April to August 2004, 626 fish were captured. Endoparasites and diet were examined following traditional methods. Cluster analyses were used to evaluate the distribution patterns of the endoparasite communities, and to evaluate similarities in the prey composition per locality. Results The endoparasite fauna of S. capensis consisted of four species widely distributed along the Pacific coast: Ascarophis cf. sebastodis, Anisakis sp., Corynosoma australe, and Pseudopecoelus sp. Other parasites were distributed only in some geographical areas. The species richness of the parasite communities increased with latitude along the Pacific coast, while parasite communities from Argentina and South Africa showed low species richness. Cluster analyses based on endoparasite composition and on prey composition grouped localities in a way consistent with known biogeographical areas for marine free‐living organisms. Main conclusions The endoparasites of S. capensis exhibit a pattern associated with known biogeographical areas for free‐living organisms. The latitudinal increase in endoparasite community richness is associated with changes in prey composition (intermediate hosts) and also possibly with the presence of definitive hosts. Therefore, the biogeographical patterns of prey are considered key determinants of the endoparasite community structure of the host.     

Zoogeography of the shallow-water holothuroids of the western Indian Ocean

Aim To analyse the zoogeography of the shallow‐water holothuroids of the western Indian Ocean (WIO). Based on this analysis we ask to what extent differences in species’ ability to disperse across potential barriers provide an explanation for holothuroid zoogeography. Location Shallow‐waters (50 m isobaths) of the WIO, extending from Suez to Cape Town and from the coastline of East Africa upward to 65° E. Methods Data for the analysis were obtained from Samyn's (2003) monograph on the shallow‐water sea cucumbers of the WIO. A species presence/absence matrix with a resolution of 1° latitude/longitude was constructed. These cells were assigned to eight coarser operational geographical units, which were delimited on the basis of published faunistic and geological borders. The analytical zoogeographical methods employed were cluster analysis on several β‐diversity coefficients and parsimony analyses of endemicity. The influence of life‐history strategies on the distribution pattern was analysed through examination of latitudinal and longitudinal gradients, and by plotting cumulative curves for species number against range size. Results The shallow‐water holothuroid fauna of the WIO can be split into several biogeographical units. To the north, we found evidence that the northern Red Sea holothuroid fauna differs from that of the southern Red Sea. The latter has closest affinity with south‐east Arabia and the Persian Gulf, and thus the biogeographical barrier of Bab‐el‐Mandab nowadays seems to be of minor importance. The cold upwelling at the east coast of Somalia forms an effective barrier for holothuroids and especially those with lecitothrophic (short‐lived) larvae. Even though the circumtropical biogeographical pattern is not well resolved, important taxonomic turnovers suggest that it is composed of several distinct subprovinces. Taxonomic turnover is at least partially dictated by the dispersion capacity of the different orders. Main conclusions This study concludes that the WIO is best split into at least three biogeographical realms: (1) the Red Sea and associated Arab Basin, (2) the asymmetrical circumtropical region stretching from the horn of Africa to southern Mozambique, and (3) southern Africa. Conspicuous differences in dispersal abilities of the three dominant orders are identified. The biogeography of the WIO is best explained by: (1) species’ dispersion ability, (2) the prevalent current patterns, and (3) to a lesser, geographically limited extent, recent geological history. As a serendipitous discovery, we found that Rapoport's rule does not hold in the WIO.     

Being abundant is not enough: a decrease in effective population size over eight generations in a Norwegian population of the seaweed, Fucus serratus

The brown alga Fucus serratus is a key foundation species on rocky intertidal shores of northern Europe. We sampled the same population off the coast of southern Norway in 2000 and 2008, and using 26 microsatellite loci, we estimated the changes in genetic diversity and effective population size (Ne). The unexpectedly low Ne (73-386) and Ne/N ratio (10-3-10-4), in combination with a significant decrease (14%) in allelic richness over the 8-year period, suggests an increased local extinction risk. If small Ne proves to be a common feature of F. serratus, then being abundant may not be enough for the species to weather future environmental changes.     

Trophic overlap between sexes in the dimorphic African black oystercatcher foraging on an alien mussel

Sex‐specific feeding segregation related to sexual bill dimorphism has been described in several oystercatcher species, including the African black oystercatcher. For the latter, studies concerned only a small number of breeding pairs and were done prior the invasion of the South African rocky shores by the Mediterranean mussel, which is believed to have benefited oystercatchers by increasing overall biomass. Here, we investigated geographic variability in the segregation of diet, biometrics and body condition between sexes in the African species, in relation to changes in foraging habitats along the South African coastline, using stable isotope analyses. Males and females and their potential prey (mussels, limpets, polychaetes and ascidians) were sampled on the southern African west, south‐west and south‐east coasts for stable isotope analyses and biometrics and body conditions of birds were measured. Bill dimorphism occurred throughout the study area and south‐west males had lower body conditions than other males and females in general. Sexes displayed little differences in their δ¹³C ratios and in the relative consumption of the different prey throughout the study area, except on the south‐east coast where males were slightly depleted in ¹³C relative to females and the most abundant prey elsewhere (the Mediterranean mussel) is rare. Females were slightly but significantly enriched in ¹⁵N by 0.3‰ compared to their breeding partners and this did not link clearly to differences in diet. We argue that the combined effect of biogeographic variations in rocky shores diversity and biomass, heterogeneous invasion by the Mediterranean mussel on the South African coastline and bill dimorphism may have altered the sex‐specific feeding behaviour of oystercatchers differently between coastal regions and possibly had an additional cost for male oystercatchers faced with lower prey biomass and diversity on the south‐west coast.