|Abstracts from The Society’s Meeting, organised by Dr Katrin Linse,at the British Antarctic Survey, Cambridge, on Thursday 15th September 2005|
Scales in biogeographic analysis
British Antarctic Survey, High Cross, Mading1ey Road, Cambridge CB3 OET, UK
The results of studies on biodiversity reflect the scale at which the work is done. Small-scale patterns are usually locally influenced and can change over short periods of time. Large-scale diversity patterns on a global scale may take millions of years to develop. Here we examine regional and local variation in biodiversity in a large-scale marine ecosystem, the Southern Ocean.
Using the Mollusca as a model taxon in a pre-defined area, the Southern Ocean south of the Polar Front, we examined the range, availability and quality of the known species distribution data. Because of the irregular geographical distribution of the data it was important to split the study area into grids to enable the grouping of neighbouring samples. Test grids, ranging from half a degree of latitude by half a degree of longitude up to 5 by 5 degrees, were used in a range of analyses to determine the optimum scale for future investigations.
Multivariate statistical techniques were used to compare the species assemblages in each grid square. Grouping similar assemblages together enabled us to determine a new set of biogeographic sub-regions within the Antarctic. These regions were then compared with neighbouring areas both inside and outside of the Polar Front. We went on to look at levels of diversity, endemism and similarity in species assemblages.
Mollusc diversity of Mediterranean subtidal rocky communities. Spatio-temporal changes at the regional spatial scale detected with multivariate analysis: consequences for latitudinal comparisons
Dip.Te.Ris., Universita di Genova, C.so Europa 26, Genova, 1-16132, Ita1ia
The Mediterranean Sea has a long scientific history and its biota are quite well described and understood. However, quantitative information on the pattern of distribution of species at different temporal and spatial scales of variation is still very poor. In this contribution, the distribution of mollusc assemblies across and along vertical rocky cliffs were assessed at two different Marine Protected Areas (AMPs), 45 kilometres far from each other, in the Ligurian Sea (NW Mediterranean Sea). At each of these locations, the MPA of Portofino and the MPA of Cinque Terre, three different sites, approximately l00m apart, were investigated. Three depths (5, 15, 25m) were sampled at each site, by using an air lift (mesh size 1 mm) and scraping off the substratum within three replicates of 30x30 cm quadrats. Sampling was performed twice in a year, with one time in the summer season and one in winter. Samples yielded more than 12707 specimens, referred to 235 species.
Multivariate analyses (nMDS, ANOSIM, SIMPER) were performed to characterize the assemblies and showed that the structure of the assemblages, between and among the two locations, differed significantly both in spatial and temporal patterns.
It is concluded that characterizing the assemblies at a fine level of taxonomic resolution, disentangling patterns of distribution at different temporal and spatial scales, is a fundamental step before any gradient, i.e. latitudinal, could be satisfactorily evaluated or addressed.
Distribution and variability in global squid fisheries
British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 GET, UK
Squid fisheries are becoming increasingly important throughout the world, currently accounting for some 3% of global landings. This work examines the development of methods for studying biogeography in some of the major fisheries for squid. Over the last decade a number of Geographic Information Systems (GIS) have been developed integrating fishery and environmental data for the analysis of patterns of spatial and temporal variability in relation to physical and biological oceanography. More recently, the use of satellite-derived imagery has been used in several studies of fisheries distribution. Many squid fisheries use powerful incandescent lights to attract their quarry and these lights are detectable using data obtained by the United States Defence Meteorological Satellite Program - Operational Linescan System (DMSP-OLS). Satellite-derived fishing-light data can be used to provide synoptic imagery of the fleet for time periods from a single day to several years and has allowed the study of fleet activity across management and political boundaries, revealing patterns of migration and inter-annual variability in a number of populations.
Biogeography of teredinids
Institute of Marine Sciences, University of Portsmouth, Ferry Road, Portsmouth P04 9L Y, UK
All members of the family Teredinidae (Bivalvia) burrow into firm substrates. Kuphus burrows into mud, while Zachsia burrows into roots of seagrass. All other teredinid genera burrow into and feed on wood. The teredinids also use their gills for suspension feeding.
Teredinids are distributed from temperate to tropical waters, with some species quite eurythermal. Some species are stenohaline (brackish or full salinity specialists) and others show a considerable euryhaline range of distribution.
Dispersal is by means of planktonic larvae, but also in drifting wood and in wooden boats. Some species have teleplanic larvae. The current distribution of teredinids is likely to have been significantly influenced by movements of wooden boats and by the construction of wooden wharves.
Puzzles are presented by the distribution of teredinids. Information regarding the relatively limited teredinid fauna in European waters and the much richer one in New Guinea waters will be presented. Up to ten species have been collected in a single panel exposed for a period of months in waters around Papua New Guinea. As all ofthese species feed by a mixture of suspension feeding and wood particle ingestion, it is intriguing to speculate about how these species can co-exist. Differences between the species that my permit sympatry include differences in life history strategy (particularly in the length of the larval period and time to maturity), in tolerance of mangrove defence mechanisms and in the relative importance of wood and phytoplankton in the diet.
Scientific Studies and the Conservation of Marine Ecosystems
English Nature, Northminster House, Peterborough PEl 1 UA, UK
There is growing recognition that the seas around the UK coasts are in a state of decline. Various reports including the Review of Marine Nature Conservation have implicated issues such as fisheries and water quality as priority areas to be tackled by UK Government, and emerging processes such as seawater temperature rise and acidification further add to the challenge. Government is responding to these concerns with the introduction of a Marine Bill which will aim to consolidate legislation for consenting, planning, fisheries and conservation. The Bill will aim to take a whole ecosystem view to understaning the marine environment, and is expected to contribute to DEFRA's vision of 'clean, safe, healthy and biologically productive seas'. This talk will examine the role that science and basic ecological studies should play in understanding complex marine ecosystems, and how this knowledge can be used to influence policy decisions relating to the exploitation of the marine environment.
Speciation and diversity of littorinid snails on rocky shores of the Indo- West Pacific
Suzanne Williams, David Reid, Tim Littlewood
Zoology Dept, Natural History Museum, Cromwell Rd, London SW7 5BD, UK
A phylogenetic approach to the origin and maintenance of species diversity ideally requires the sampling of all species within a clade, confirmation that they are evolutionarily distinct entities, and knowledge of their geographical distributions. In the marine tropics such studies have mostly been of fish and reef-associated organisms, usually with high dispersal. In contrast, snaiIs of the genus Echinolittorina (Littorinidae) are restricted to rocky shores, have a 4-week pelagic development (and recorded dispersal up to 1400 km) and show different evolutionary patterns. We present a complete molecular phylogeny of Echinolittorina, derived from Bayesian analysis of sequences from nuclear 28S rRNA and mitochondrial 12S rRNA and COl genes (nodal support indicated by posterior probabilities, maximum likelihood and neighbor-joining bootstrap). This consists of 59 evolutionarily significant units (ESUs), including all 50 known taxonomic species. The 26 ESUs found in the Indo-West Pacific region form a single c1ade, whereas the eastern Pacific and Atlantic species are basal. The earliest fossil occurred in the Tethys during the middle Eocene and we suggest that the lndo-West Pacific clade has been isolated since closure of the Tethyan seaway in the early Miocene. The geographical distributions of all species (based on over 3700 locality records) appear to be circumscribed by barriers of low temperature, unsuitable sedimentary habitat, stretches of open water exceeding about 1400 km, and differences in oceanographic conditions on the continuum between oceanic and continental. The geographical ranges of sister species show little or no overlap, indicating that the speciation mode is predominantly allopatric. Furthermore, range expansion following speciation appears to have been limited, because a high degree of allopatry is maintained through three to five branching points of the phylogeny. This may be explained by infrequent long-distance colonisation, habitat specialisation on the oceanic/continental gradient, and perhaps by interspecific competition. In the eastern Pacific plus Atlantic we identify five cases of divergence on either side of the Isthmus of Panama, but our estimates of their ages pre-date the emergence of the Isthmus. There are three examples of sister relationships between species in the western Atlantic and eastern Atlantic, all resulting from dispersal to the east. Within the Indo-West Pacific, we find no geographical pattern of speciation events; narrowly endemic species of recent origin are present in both peripheral and central parts of the region. Evidence from estimated divergence times of sister species, and from a plot of the number of lineages over time, suggest that there has been no acceleration of diversification during the glacio-eustatic cycles of the Plio-Pleistocene. In comparison with reefal organisms, species of Echinolittorina on rocky shores may be less susceptible to extinction or isolation during sea-level fluctuations. The species richness of Echinolittorina in the classical biogeographic provinces conforms to the common pattern of highest diversity (11 species) in the central 'East Indies Triangle' of the Indo-West Pacific, with a subsidiary focus in the eastern Pacific and western Atlantic, and lowest diversity in the eastern Atlantic. The diversity focus in the East Indies Triangle is produced by a mosaic of restricted allopatric species and overlap of a few widespread ones, and is the result of habitat specialisation rather than historical vicariance. This study emphasizes the plurality of biogeographic histories and speciation patterns in the marine tropics.
Williams, S.T and D.G. Reid (2004) Speciation and diversity on tropical rocky shores: a global phylogeny of snaiIs of the genus Echinolittorina. Evolution 38: 2227-2251.
Divergence time estimates for major cephalopod groups: evidence from multiple genes
Jan Strugnell, Jennifer Jackson, Alexei J. Drummond, Alan Cooper
Molecular Evolution, Dept. of Zoology, South Parks Rd, Oxford, OXl 3PS, UK
This is the first study to use both molecular and fossil data to date the divergence of taxa within the coleoid cephalopods (octopus, squid, cuttlefish). A dataset including sequences from three nuclear and three mitochondrial genes (3415 bp in total) was used to investigate the evolutionary divergences within the group. Divergence time analyses were performed using the Thorne/Kishino method of analysis which allows multiple constraints from the fossil record and permits rates of molecular evolution to vary on different branches of a phylogenetic tree. The data support a Paleozoic origin of the Orders Vampyromorpha, Octopoda and the majority of the extant higher level decapodiform taxa. These estimated divergence times are considerably older than paleontological estimates. The major lineages within the Order Octopoda were estimated to have diverged in the Mesozoic, with a radiation of many taxa around the Cretaceous/Cenozoic boundary. Higher level decapodiform phylogenetic relationships appear to have been obscured due to an ancient diversification of this group.
Katrin Linse welcomes participants at the start of the meeting at the British Antarctic Survey in Cambridge.
A Visit behind the scenes at
the British Antarctic Survey
1. Outside aquarium: Left to right: Soren Pears, Simon Cragg, David Barnes, Heike Waegele, Lucy Turner.
2. Harpagifer antarcticus.
3. A: Odontaster validus, B: Nacella concinna, C: shallow water actinian, D: Neobuccinum eatoni, E: Marseniopsis mollis, F: Odontaster meridionalis.
4. Lapidiaster eatoni.
5. Pycnogonid: Decalopoda australis, Bivalves: Laternula elliptica.
6. Simon Cragg, Lucy Turner, Katrin Linse and Heike Waegele outside container being packed for shipping to Antarctica.
7. Katrin with a specimen pycnogonid in the spirit store.