Freshwater invertebrate fauna of the Tristan da Cunha islands (South Atlantic Ocean), with new records for Inaccessible and Nightingale Islands
- Authors: Barber-James, Helen M
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7001 , http://hdl.handle.net/10962/d1008360
- Description: As part of a multidisciplinary floristic-faunistic study, a three week survey of the invertebrate fauna of Inaccessible Island (South Atlantic Ocean) was carried out in October / November 1989. In addition, one day of collecting was done on Nightingale Island. This paper deals only with the fauna associated with freshwater ecosystems from these islands, some of which are usually associated with marine or brackish conditions. On Inaccessible Island, five distinct types of freshwater body were identified - pH neutral streams, acidic streams (pH 5), an open pool of standing water (pH 6), areas of acidic bog, and seepages down rock faces. The survey, the most comprehensive for Inaccessible Island to date, has resulted in the discovery of 19 aquatic invertebrate species previously unrecorded on Inaccessible Island, two new to Nightingale Island, and 14 of which are new to the Tristan da Cunha archipelago. Many of the species are known from other parts of the world, indicating a low degree of endemicity within the freshwater invertebrate community. Recolonisation from the source populations, preventing an isolated gene pool, may account for the low endemicity. Several of the species have a degree of salinity tolerance, enabling them to withstand transportation across tracts of ocean, and others have marine origins.
- Full Text:
- Date Issued: 2007
- Authors: Barber-James, Helen M
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7001 , http://hdl.handle.net/10962/d1008360
- Description: As part of a multidisciplinary floristic-faunistic study, a three week survey of the invertebrate fauna of Inaccessible Island (South Atlantic Ocean) was carried out in October / November 1989. In addition, one day of collecting was done on Nightingale Island. This paper deals only with the fauna associated with freshwater ecosystems from these islands, some of which are usually associated with marine or brackish conditions. On Inaccessible Island, five distinct types of freshwater body were identified - pH neutral streams, acidic streams (pH 5), an open pool of standing water (pH 6), areas of acidic bog, and seepages down rock faces. The survey, the most comprehensive for Inaccessible Island to date, has resulted in the discovery of 19 aquatic invertebrate species previously unrecorded on Inaccessible Island, two new to Nightingale Island, and 14 of which are new to the Tristan da Cunha archipelago. Many of the species are known from other parts of the world, indicating a low degree of endemicity within the freshwater invertebrate community. Recolonisation from the source populations, preventing an isolated gene pool, may account for the low endemicity. Several of the species have a degree of salinity tolerance, enabling them to withstand transportation across tracts of ocean, and others have marine origins.
- Full Text:
- Date Issued: 2007
Global diversity of mayflies (Ephemeroptera, Insecta) in freshwater
- Barber-James, Helen M, Gattolliat, Jean-Luc, Sartori, Michel, Hubbard, Michael D
- Authors: Barber-James, Helen M , Gattolliat, Jean-Luc , Sartori, Michel , Hubbard, Michael D
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7002 , http://hdl.handle.net/10962/d1008361
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
- Full Text:
- Date Issued: 2007
- Authors: Barber-James, Helen M , Gattolliat, Jean-Luc , Sartori, Michel , Hubbard, Michael D
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:7002 , http://hdl.handle.net/10962/d1008361
- Description: The extant global Ephemeroptera fauna is represented by over 3,000 described species in 42 families and more than 400 genera. The highest generic diversity occurs in the Neotropics, with a correspondingly high species diversity, while the Palaearctic has the lowest generic diversity, but a high species diversity. Such distribution patterns may relate to how long evolutionary processes have been carrying on in isolation in a bioregion. Over an extended period, there may be extinction of species, but evolution of more genera. Dramatic extinction events such as the K-T mass extinction have affected current mayfly diversity and distribution. Climatic history plays an important role in the rate of speciation in an area, with regions which have been climatically stable over long periods having fewer species per genus, when compared to regions subjected to climatic stresses, such as glaciation. A total of 13 families are endemic to specific bioregions, with eight among them being monospecific. Most of these have restricted distributions which may be the result of them being the relict of a previously more diverse, but presently almost completely extinct family, or may be the consequence of vicariance events, resulting from evolution due to long-term isolation.
- Full Text:
- Date Issued: 2007
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