Chapter 2: State and Trends
important threats to Caribbean reefs, affecting up to 70 per cent of these ecosystems (Burke et al. 2011).
Threatened species
According to the Living Planet Index, between 1970 and 2010, the size of vertebrate populations in the Neotropics decreased by 83 per cent; this is the highest figure observed in any region around the world (Figure 2.5.9; McRae et al. 2014). The main pressures driving reductions in species are pollution, invasive alien species, habitat loss and climate change (WWF 2014).
Based on the latest data published in the Red List of threatened species by the International Union for Conservation of Nature (IUCN), approximately 10 831 species in LAC are considered at risk (IUCN 2015). This figure is probably an underestimate because of gaps in information about many species. For example, at least 42 per cent of LAC´s amphibian species, 37 per cent of mammal species, 25 per cent of bird species and 18 per cent of reptile species are threatened (Figure 2.5.9).
Modelling indicates that while the Amazon forest has retained a large proportion of its original species diversity, other ecosystems have lost significant diversity (Figure 2.5.10) (Newbold et al. 2015).
Invasive Alien Species
Although knowledge about Invasive Alien Species has been growing in the LAC region, there are still a number of gaps in the data. There are a few national lists with some still in preparation. The list of invasive species for the Caribbean, produced more than a decade ago, reported 416 species, many already present on the mainland (Kairo and Ali 2003). In Mexico, 213 invasive species have been reported in terrestrial ecosystems, 93 in freshwater and 71 in coastal environments (Mexico- SEMARNAT 2015). In Colombia and Argentina, 581 and 600 species have been classified as invasive respectively (FAO 2015d).
In the terrestrial realm, some examples of dangerous IAS established in some LAC countries are the yellow crazy ant (Anoplolepis gracilipes), the chytrid frog fungi (Batrachochytrium dendrobatidis), the cannibal snail (Euglandina rosea), and the small Indian mongoose (Herpestes auropunctatus). For freshwater and marine ecosystems have been registered the zebra mussel (Dreissena polymorpha), the European green crab (Carcinus maenas), the water hiacynth (Eichhornia crassipes) and the common pleco (Hypostomus plecostomus), among others (ISSG 2015).
Marine ecosystems in the Caribbean have recently been affected by the invasion of lionfish. Through accidental and/ or intentional release into the Atlantic, lionfish have become established in coral reefs in Bermuda, Florida, the Gulf of Mexico, the Caribbean islands, Mesoamerica, and northern South America.
Genetic diversity
Although the current information in the region is not sufficient to accurately assess the state of the genetic diversity of cultivated species, national reports to FAO´s State of World´s Plant Genetic Resources (FAO 2016) indicate significant problems of genetic erosion of crops and their wild relatives in the region.
The adoption of improved crop varieties by farmers is perhaps the most relevant factor causing genetic erosion in the region. For a long time it has been thought that use of improved varieties may result in increasing yields and gains for farmers, which under some circumstances could not be entirely true. In Mexico, the loss of local varieties of maize (currently 59 races of maize and its relative teosinte have been described in this country), is driven by improved varieties: about 70 per cent of the area sown with maize in the States with greatest production uses improved maize seeds (Molina and Córdova 2006; Berthaud and Gepts 2004). In Chile, Chiloé´s farmers prefer commercial improved potatoes to traditional varieties: before the introduction of new varieties the local communities grown between 800 and 1 000 potato varieties; currently just about 270 varieties are
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