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 ext
Trang 1and 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
Infor-mation 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
in-vertebrate 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
distri-bution 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
ter-restrial 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
or-ganisms 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 2 or 3 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 aban-donment (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 ter-restrial 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 island-like 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 (Bo¨nsel 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 agri-cultural practices and urbanization, and those habitat that are still relatively intact are usually highly fragmented Fragmen-tation 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
dis-appeared 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
220 Endangered Terrestrial Invertebrates