The extent of semi‐natural grassland has diminished considerably across lowland landscapes of England and Wales during the second half of the twentieth century. Locating, describing and evaluating the dwindling cover has been a major challenge for conservationists. A concentrated vegetation survey effort at grassland sites has been mounted within different parts of Britain since the late 1970s. Plant community recognition has benefited considerably from the development of the contemporary National Vegetation Classification, and its widespread adoption permits national inventory of comparable vegetation data. Findings of a range of surveys (ninety‐eight in total), undertaken between 1978 and 1996 in England and Wales covering different forms of unimproved lowland grassland, are collated and reviewed. Vegetation data were abstracted from internally published survey reports. Calcicolous and neutral grasslands have been covered more thoroughly than acidic and wet or marshy grasslands. Cover data are summarized at community level. Overall estimates from survey results indicate that there are some 27 500–40 000 ha of calcicolous grassland, 7500–15 000 ha of unimproved neutral pasture and hay meadow, 8000–15 000 ha of acidic grassland and 9000–17 500 ha of wet grassland in lowland England and Wales; these represent only 1–2% of the cover of permanent lowland grassland. Some communities have additional representation in heathlands, mires and upland environments. Although they require further refinement, the cover data for individual communities provide a context for assessing priorities in site‐based and agri‐environment conservation programmes. It is concluded that, as well as arresting further depletion, it will be necessary to restore and expand lowland grassland habitats to counteract the negative impacts of fragmentation and isolation of various community types, such as the Centaureo–Cynosuretum, which is widely but thinly distributed. Habitat rehabilitation schemes also need to assimilate local patterns of community diversity characteristic of both wet and dry grasslands. It is suggested that reversal of the recent successional trends that followed relaxation of grazing at certain sites might produce a more appropriate balance in the relative cover of coarse tall grasslands and fine short turf. Vegetation surveys provide a source of spatial data for identifying local aggregations of semi‐natural grassland remnants.
The origins of giraffe's imposing stature and associated cardiovascular adaptations are unknown. Okapi, which lacks these unique features, is giraffe's closest relative and provides a useful comparison, to identify genetic variation underlying giraffe's long neck and cardiovascular system. The genomes of giraffe and okapi were sequenced, and through comparative analyses genes and pathways were identified that exhibit unique genetic changes and likely contribute to giraffe's unique features. Some of these genes are in the HOX, NOTCH and FGF signalling pathways, which regulate both skeletal and cardiovascular development, suggesting that giraffe's stature and cardiovascular adaptations evolved in parallel through changes in a small number of genes. Mitochondrial metabolism and volatile fatty acids transport genes are also evolutionarily diverged in giraffe and may be related to its unusual diet that includes toxic plants. Unexpectedly, substantial evolutionary changes have occurred in giraffe and okapi in double-strand break repair and centrosome functions.
Boring sponges belonging to the family Clionaidae have become a destructive nuisance to eastern oyster (Crassostrea virginica) aquaculture and restoration efforts in the southeastern USA. Clionaid sponges colonize the inner layers of oyster shells and remove carbonate material, compromising the quality and marketability of the oyster; however, relatively little is known about reproduction and recruitment of these sponges. Using histological techniques, reproductive activity of clionaid sponges was monitored at two sites (Cedar Island and Masonboro Sound) in coastal North Carolina. Sponge recruitment to limestone tiles (5×5 cm), oyster shells, and clam shells was monitored in 2013 and 2014; recruitment to the limestone tiles was statistically higher than recruitment to clam or oyster shells. Overall, seasonal patterns in reproduction and recruitment of clionaid sponges were generally similar at the two sites. Three species of clionaid sponge were found during field sampling (Cliona celata, C. lobata, and C. truitti), and reproductive activity (eggs and spermatocysts) of these species was observed from April to November, with peak reproduction occurring from June to September for C. lobata and from August to September for C. celata. Recruitment peaked in late summer/early fall. Additionally, the relationship between environmental conditions (temperature, salinity, dissolved oxygen, pH, and chlorophyll a) and clionaid recruitment was explored using a regression model. At Cedar Island, the best‐fit model included salinity and dissolved oxygen, while the best‐fit model at Masonboro Sound included temperature, pH, and salinity. The data from this study show that the primary reproduction and recruitment pulses occur in the fall for local clionaids, and thus mitigation strategies should be applied in the late fall or winter to minimize infestations.
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