the status of the world’sland and marine mammals :diversity, threat, andknowledgeArticle written by: Jan Schipper, Janice S. Chanson, Federica Chiozza, et al.Presentation by: Carolina Fernandez
Vocabulary Taxonomy: orderly classification of plants and animalsaccording to their presumed natural relationships Estuarine(estuary):An estuary is a partly enclosedcoastal body of brackish water with one or more riversor streams flowing into it, and with a free connection tothe open sea. Invasive species- non-native species. Discontinuity: A distinct break in physical continuity orsequence in time.
ContextThis article was written in order to inform people about the mostcurrent news concerning the mammals we coexist with. Every couple ofyears an assessment of all the newest and oldest mammals is taken.The IUCN remains committed to providing the world with the mostobjective, scientifically based information on the current status of globalbiodiversity. The IUCN stands for the International Union forConservation of Nature, formerly the World Conservation Union. Theyalso focus on investigating which animals are at risk of extinction andwhat we as neighbors of mammals could do to prevent their extinction.The current dataset on mammals is the product of a similar initiative toundertake a global, comprehensive assessment of the conservationstatus of all mammalian species. Prior to this assessment, the last timeall mammals were assessed globally was in 1996(4), and the majorityof those assessments are out-of-date. Overall, the article includes aload of information, incorporating data on distribution, populationnumbers and trends, habitat, life history, threats, conservation actions,conservation status, and utilization for each individual wild mammalspecies.
Experimental DesignData were analyzed using a geodesic discrete global grid systemwhich consists of a set of regions that form a partition of theearth’s surface, where each region has a single point contained inthe region associated with it. The maps take the form of broadpolygons that join known locations. A species’ distribution map canconsist of more than one polygon where there is an obviousdiscontinuity in suitable habitat. For some range-restrictedmammals, they tried to map distribution ranges with a higherdegree of accuracy, sometimes down to the level of individualsubpopulations. The range of each species was converted to thehexagonal grid for analysis purposes, with land and marine cells(and their species) analyzed separately. Coastal cells were clippedto the coastline into land and marine sections. The ranges of‘cross-realm’ species were also clipped to the coastline into landand marine sections, and analyzed accordingly with land andmarine cells. The maps created in each analysis have patterns formarine species mapped on a blue scale, and patterns for landspecies mapped on a brown scale. Different numerical scales areused for land and marine, as the numbers of species differ by morethan an order of magnitude. Patterns of species richness (weremapped by counting the number of species in each cell (or cellsection, for species with a coastal distribution).The IUCN Species Survival Commission is an establishedknowledge network of ~8,000 volunteer members working inalmost every country of the world. SSC members are deployed inmore than 120 Specialist Groups and Task Forces, with some2,000 members being part of the mammal Specialist Groupnetwork. Currently, there are 29 Specialist Groups with ataxonomic focus on mammals (6), and one stand-alone Red ListAuthority. For the purpose of conducting careful detailed review ofall mammal assessments, a series of 28 workshops wereconducted in 18 countries around the world (and usually incollaboration with existing Specialist Groups).
Presentation of DataNumber and percentage of species affected by each of six main threatcategories. Species can be affected by more than one threat category;being affected by a threat does not necessarily imply that the speciesis globally threatened (Vulnerable, Endangered, or CriticallyEndangered).For each species, data was collected on species, genus, family,order, taxonomic authority, English and other common names (ifany), and taxonomic notes (if needed, normally used to clarifydifficult or confusing issues). Although the IUCN Red List is notintended to be a definitive taxonomic source, it strives to betaxonomically coherent and consistent at all ranks.
The separation betweenland and marine specieswas purely based on theirmapped ranges, not onthe habitats that they use.As a result, some that usemarine habitats weremapped completely inland. These includefreshwater and/orestuarine species thatoccupy a marine area thatis too narrow to map, forexample: Eurasian Otter(Lutra lutra), which insome parts of its rangeforages within a fewhundred meters offshore(36); Water Rat(Hydromys chrysogaster),a mainly freshwater andbrackish water speciesthat also uses coastalmangroves (37).
DiversityLand species have particularly high levels of species richness in theAndes and in the Afromontane regions in Africa such as theAlbertine Rift. High species richness could also be found in Asia,mostly in the Hengduan mountains of southwestern China. Theranges of many large mammals have recently contractedsignificantly in tropical Asia, so local diversity has decreased inrecent years. Overall the species richness in land mammals issimilar to that found for birds and amphibians which suggests thatdiversity is similarly driven by energy availability and topographiccomplexity.Marine mammals concentrate in tropical and temperate coastalplatforms, as well as in offshore areas in the Tasman andCaribbean seas, east of Japan and New Zealand and west ofCentral America, and in the Southern Indian Ocean.The range of most marine mammals is smaller than one-fifth of theIndian ocean.
Extinction and New lifeTwenty five percent of all mammals for which data hasbeen collected are threatened with extinction. The exactthreat level is unknown. Critically endangered species alsoface a high probability of extinction, and for some(about 29species) it may already be too late for salvation. Speciesnot classified as threatened aren’t particularly excludedfrom endangerment. Many species have experienced largerange and population declines in the past.Although mammals are among the best known organisms,they are still being discovered. The number of recognizedspecies has increased by 19% since 1962 and includes 349newly discovered species. Newly described mammals arepoorly known, which has a negative impact on their survivalrate, concerning researchers with the fact that certainspecies may be extinct before even being discovered.
Data AnalysisThese trends indicate that the overall conservation status ofmammals will likely deteriorate further in the near future,unless appropriate actions are taken to guide the future inanother direction. On the bright side, at least 5% ofcurrently threatened species have stable or increasingpopulations. These results paint an ugly picture of theglobal status of mammals worldwide. It is estimated thatone in four species is threatened with extinction and thatthe population of one in two is declining. Despite a generaldecline in the status of mammals, there is a possibility ofprogress through our own conservation efforts.
Unanswered Questions What kind of steps must we take in order to reallyprotect these mammals? Do we have an equal or bigger part in the extinction ofspecies than the natural process or climate?
ReferencesSupporting Online Material (SOM) for:The status of the world’s land and marine mammals:diversity, threat, and knowledge. (PDF)