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Encyclopedia of biodiversity encyclopedia of biodiversity, (7 volume set) ( PDFDrive ) 1803

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220 Endangered Terrestrial Invertebrates and distribution of taxonomic identification tools easier and less expensive, but efforts are still hampered by the insufficient numbers of taxonomists capable of their development Several international initiatives, such as Global Biodiversity Information Facility (GBIF) or Encyclopedia of Life (EOL), have been involved in the efforts to accelerate digital distribution of tools to reduce the taxonomic impediment The development of rapid and inexpensive genetic sequencing technologies has lead lately to a more widespread use of genetic barcodes, small fragments of (usually mitochondrial) deoxyribonucleic acid (DNA) to identify species Large, comprehensive databases of genetic barcodes and automated, widely available sequencing will likely soon lessen the taxonomic impediment in invertebrate conservation There is evidence that areas too small to support endemic species of vertebrates (e.g., the Antioch Dunes of California) have rich faunas of endemic invertebrates, which are at risk of extinction due to relatively small alteration of those habitats The current general paucity of expertise in invertebrate taxonomy and identification as well as insufficient efforts to sample and document terrestrial invertebrates in threatened habitats may lead to the negative phenomenon known as Centinelan extinction, understood as the extinction of species before their very existence is recognized and documented While, by the very definition of the process, it is difficult to prove Centinelan extinction, the existing knowledge of distribution ranges and dispersal abilities of many invertebrate taxa support the notion that the disappearance or anthropogenic alteration of natural habitats will lead to extirpation of species restricted to those habitats; in the case of Antioch Dunes the extinction of endemic invertebrates, such as the Shield katydid (Neduba extincta) following the habitat alteration, has already been demonstrated Life Histories A compounding factor in efforts to monitor and protect terrestrial invertebrates is the presence of polymorphism and complex life cycles in many of their species, where immature forms may have very different appearance and habitat requirements than the adult forms For example, insects that undergo complete metamorphosis as a rule have very different microhabitat and food requirements than the adults, such as caterpillars of butterflies that often require very specific food plants, different from those that adults use to obtain their nutrients (Van Swaay et al., 2010) Many invertebrates that are terrestrial as adults spend their entire larval development in the water (e.g., dragonflies, mayflies, or some midges) An extreme example of the disjunction between the adult and larval lifestyle is the coconut crab (Birgus latro), the largest living terrestrial invertebrate, whose early developmental stages include oceanic, pelagic larvae This means that any attempts in species- or habitat-level conservation of such organisms must take into consideration all requirements and environments needed by them None of the terrestrial invertebrates lives in isolation from other members of its biological communities, and many form obligatory, symbiotic relationships with other species A good example of such association is that between blue butterflies (Lycaenidae) and ants European Scarce Large Blue (Phengaris teleius) is a species whose caterpillars need to be picked up by worker ants of the genus Myrmica and carried off to the ants’ nest, where they feed on ant grubs and eventually pupate In addition, young caterpillars of this species need to feed on the shrub Sanguisorba officinalis for the first or weeks of their life Because of such complex life history, this butterfly is vulnerable to any changes in the environment that affect either the host plants or host ants, and in large parts of its range, this species declines because of either intensification (e.g., drainage, fertilization, and use of pesticides) or abandonment (where its habitat gets invaded by scrubs and later forest) of its wet meadow habitat Larvae of the moth genus Ceratophaga can only survive in the keratin, such as that of horns of antelopes or shells of tortoises, and thus are dependent on the existence and availability of their vertebrate hosts A special case of complex, symbiotic life histories in terrestrial invertebrates is parasitic relationships between insects and their hosts This includes not only such well-known (and negatively perceived) cases as lice and fleas on vertebrate hosts but also parasitoids and hyperparasitoids that develop in other insects Braconid wasps, ichneumonid wasps, or meloid beetles all require other insect species to complete their life cycles, and the decline or loss of the host species invariably leads to decline or loss of the parasitic ones Threats to Terrestrial Invertebrates Habitat Loss and Fragmentation The principal threat to the survival of terrestrial invertebrate species is the loss of their natural habitats There is evidence that the average distribution range sizes of invertebrate taxa are smaller than the average range sizes of vertebrates, and their dispersal abilities are also lower than those of vertebrates In addition, species associated with small, isolated or islandlike habitats (e.g., peatlands of Europe, subalpine ecosystems, and small oceanic islands) appear to have even lower dispersal abilities, and consequently are more prone to be affected by changes to those habitats, and pushed below the minimal viable size of their population (Boănsel and Sonneck, 2011; Kisdi, 2002) The highly developed parts of the world, such as Europe or the coastal regions of the USA, have already lost the majority of their natural habitats due to centuries of agricultural practices and urbanization, and those habitat that are still relatively intact are usually highly fragmented Fragmentation is considered a major factor that impacts the survival ability of many terrestrial invertebrate species that require a certain, critical minimum area of continuous habitat or habitat-dependent resources to survive For example, the American burying beetle (Nicrophorus americanus) has disappeared from over 90% of its former range within the past 150 years as a result of anthropogenic habitat loss and fragmentation of relatively continuous stands of deciduous forests across the presettlement range of this species; these fragmented habitats are now currently too small to sustain the fauna of small mammals, on carcasses of which the beetles feed, extensively enough to supports its survival Flightless

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