Appunti di Biodiversity

Factors contributing to increased extinction risk

Criterion B identifies localized endemics: species that are at risk of extinction because they only occur within a small area. Restricted ranges are however often a natural phenomenon, therefore this criterion also incorporates other factors contributing to increased extinction risk, such as: continuing decline of the habitat or population, extreme fluctuations in population size, severe fragmentation of the population into small, isolated subpopulations.

Criterion C identifies species that are at high risk of extinction due to small population size. The smaller a species' population, the higher is its risk of extinction. Species with small populations are likely to face extinction only when there is also population decline. Therefore, to classify a species as threatened with extinction under Criterion C, the

population must not only be small, but must also be declining.

D). Very small population or very restricted distribution. Criterion D primarily identifies species that are at risk of extinction due to critically small population size or very restricted distribution. Any population undergoes fluctuations in numbers because of changes in environmental conditions or simply because of the inherent randomness of breeding success and population dynamics.

E). Quantitative analysis of extinction risk (e.g., Population Viability Analysis) Criterion E is used to classify a species as threatened when a statistical analysis shows that the probability of extinction is high within a short time frame. Data on how threatening processes affect population variables such as birth and mortality rates are used to predict extinction risk. Statistical analyses require intensive and time-consuming demographic study and monitoring of species, Criterion E is not often used in Red List assessments.

For each

Criterion: There are several questions and ranges. To list a particular taxon in any of the 3 categories of threat, only one of the 5 criteria needs to be met. Only the criteria for the highest category of threat that the taxon qualifies for should be listed. (Thus, if the species is identified in more categories, only the criteria in which it falls under the worst should be listed to determine the classification of that species; for example, if a species in one criteria is considered vulnerable, and for another one is considered endangered, the species must be considered endangered). Additional criteria that the taxon qualifies for at lower threat categories may be included in the documentation.

Near Threatened (NT): is applied to taxa that do not qualify as threatened now, but may be close to qualifying as threatened, and to taxa that do not currently meet the criteria for a threatened category but are likely to do so if ongoing conservation actions abate or cease.

Least Concern (LC):

The term "least concern" is applied to taxa that do not qualify (and are not close to qualifying) as Threatened or Near Threatened. It is important to emphasize that "least concern" simply means that, in terms of extinction risk, these species are of lesser concern than species in other threat categories. It does not imply that these species are of no conservation concern, but the species should be protected anyway.

The remaining two categories (Data Deficient (DD) and Not Evaluated (NE)) do not reflect the threat status of taxa.

Which species may be assessed?

From the methodology of the IUCN list:

• The Red List Categories and Criteria can be applied to all species (except micro organisms)
• The Red List Categories and Criteria may only be applied to wild individuals within their natural range.
• When no more natural habitat remains, individuals reintroduced for the purposes of conservation in areas outside the natural range may be assessed once the population has proved to be self-sustaining.

(The reintroduction of a species in a new habitat is so successful that the population does not need any further help) The Red List Categories and Criteria are typically applied to species, but may also be applied to subspecies and varieties, or biologically isolated subpopulations of species, provided that an assessment at species level is completed first.

Newly discovered species that are not yet formally described may only be assessed under the following conditions: (1) There must be general agreement that it is clearly a distinct new species. (2) The assessment of the species must be of clear conservation benefit. (3) A voucher specimen must be available in a museum or herbarium to allow the species to be traced and identified without confusion. (4) The species must be described within four years of its inclusion in a Red List.

No hybrids, cultivars or breeds may be assessed. No domesticated individuals, or feral individuals derived from domesticated sources, may be assessed.

assessed.

• Naturalized or introduced individuals may not be assessed, unless the introduction was for the purposes of conservation

Classifying a species as threatened with extinction:

• Species at higher trophic levels: like predatory species at the top of the food chain (tuna, sharks), occur at much lower densities than their prey and other plants and animals are at lower trophic levels. They are often large animals with slow rates of growth and reproduction, to produce only a few offspring to maintain their populations. Due to the combination of low population size and slow rates of growth and reproduction, such species as tuna, sharks and similar are particularly vulnerable to overexploitation and habitat loss.

Localized endemic are generally species found in taxonomic groups where periods of environmental change have driven formerly widespread species into small pockets of suitable habitat conditions, or where species have evolved in small, isolated areas of suitable habitat.

such as islands or lakes. These species are extremely vulnerable to habitat loss and degradation which may wipe out the entire population. Species with small populations: these are typically apex predators, but also species at lower trophic levels, can also occur at very low densities. Individuals of such species easily become isolated in small, unviable groups when their habitats are fragmented as a result of transformation for human use. Ex. Vaquita. Species with poor dispersal and colonization ability: species with highly specific habitat requirements, but a poor ability to disperse to new areas of suitable habitat, are at high risk of extinction, even when their populations are relatively widespread. When their habitats are fragmented, poor dispersers are unable to recolonize areas of suitable habitat where local extinctions have occurred, and individuals become isolated more quickly. (environmental change) These species are not able to move enough to keep up with the

shifting of an habitat with suitable habitat conditions.

Species with colonial or gregarious breeding habits: wide-ranging and abundant species that gather in a single place to breed are extremely vulnerable to disturbance or destruction of their breeding sites. Many ocean-roaming seabirds, such as the Spectacled Petrel, return to a single oceanic island to breed. For example the bird that nest Procellaria conspicillata only on a specific island in the middle of the ocean, so it is vulnerable, and the island have to be kept more neutral as possible so that the species doesn't encounter dangers.

Species dependent on unreliable resources: such plants and animals usually have very short life cycles, and their population size fluctuates greatly between successive generations, depending on the availability of the resource. Such species are prone to extinction at periods when their numbers are very low.

Ecologically naive species: they have evolved without the threat of

competitors or predators (including humans), and have subsequently lost the defensive behavior patterns of their relatives. The Global marine species assessment tried to fix a goal of 20 thousand marine species assessed with the red list in the period from 2006 and 2012, but the cumulative assessment at march 2015 (after 3 years the deadline that was established to reach the goal) was still low compared with the goal. The total species assessed in 2015 were almost 77,340 of which: 22,784 threatened; 4,735 CR, 7,124 EN and 10,925 VU. This suggests how huge should be the effort that is needed to be taken to reach the goal of analyzing the species at risk of extinction, because only with that kind of information can we assess specific conservation strategies, or adopt the right one. Conservation can be examined from the perspective of individual species, biodiversity and ecosystem function and value. Conservation efforts are directed toward: (beside them are indicated also the strategies)

• Individual species
• Biodiversity
• Ecosystem function and value

usually utilized to protect those marine organisms): single species Cites

• [ ] groups of related species Marine Protected Areas
• [ ] local habitats Marine Protected Areas too
• [ ] ecosystems Network of MPA (MPA: marine protected areas)

In many cases, conservation efforts are targeted at single species for their aesthetic impact on society, and their loss is thought to reduce enjoyment of the natural environment. Ecosystem management is defined as an approach to conserve ecosystem that includes components of:

• environmental protection: to devise ways to minimize the impact of human activities on natural ecosystems
• the social community that interact with ecosystem: involve the engagement of government, non-governmental organizations, and the public in general to understand how their actions might affect an ecosystem and how ecosystem functioning might affect recreation, food source, water supply, protection against storms, and other factors important to

societyeconomic considerations

• Looking at this graph we can understand the illegal trade of animals, which is a really huge problem, along with marine animals: on the left we can see % of the species illegally commercialized, and this is a very huge problem to biodiversity because several species are going towards extinction just for economic illegal reasons.
• Hunting, picking, owning, importing, exporting, transporting, growing, breeding and trading of such species are illegal without valid permits or licenses.
• The names of protected species are listed in international conventions, national acts and provincial ordinances.
• CITES stands for Convention on International Trade in Endangered Species of Wild Fauna and Flora, and it has been adopted by many countries to protect species by international, national and provincial legislation. It's an international agreement on which more than 140 countries signed, in the late '70s, to protect biodiversity: with this agreement, parties

agreed to illegal trades, because the countries can control the export and import and so to detect which countries are illegally importing