Arthropods in biodiversity hotspots: the case of the Phytoseiidae (Acari: Mesostigmata)

Abstract

The biodiversity hotspot concept was defined by Myers in 1988 to determine priority areas for conservation. They have high endemism levels and have lost more than 70% of their original vegetated area. To date, there is little information on arthropod diversity in these zones. This work focuses on the biodiversity of the Phytoseiidae (Acari), one of the best known among the order Mesostigmata, in these threatened areas. These mites are usually predators and they are worldwide spread. Geographic distribution of phytoseiids in 27 biodiversity hostspots was assessed from data of the last world catalogue published in 2004. One thousand two hundred and thirty species are reported from at least one hotspot (62% of the total species number) and 604 species (30% of the total species number) are endemic to the 27 hotspots considered. The number of reports/publication in hotspot areas (2.6) is higher than in non-hotspot zones (1.5). Hotspots areas could be thus considered as a great reservoir of the Phytoseiidae diversity, just as they are for vertebrates and plants. Correlations between plant, vertebrate, mite diversity and endemism, as well as congruence rates between endemism levels of these three organisms suggest that the biodiversity patterns of plants and vertebrates mirror well those of the Phytoseiidae (both for endemicity and species richness). More intense conservation efforts in biodiversity hotspots would thus be assumed to affect plant and vertebrate biodiversity, as already known, but also arthropod biodiversity, as it was assumed. These results further support thus the importance of these zones in biodiversity conservation, even for organisms like mites, very small and poorly studied in this regards. More data on arthropods are, however, required to confirm these preliminary observations.

Phytoseiidae (Acari: Mesostigmata) on plants of the central region of the Brazilian Cerrado

“…In conclusion, the results suggest that few Phytoseiidae species are endemic from Cerrado, a fact also pointed out by Tixier and Kreiter (2009). However, due to the small number of surveys and the high rate of endemic plants in this biome (Myers et al 2000), these results show probably only a fraction of the real diversity of phytoseiid in the region, since the richness of animal groups tend to increase as plant diversity increases (Brose 2003;Dennis et al 1998;MacArthur and MacArthur 1961).…”

Biogeographical analysis within the family Phytoseiidae Berlese (Acari: Mesostigmata): an example from the large sub-genus Typhlodromus (Anthoseius) De Leon

“…Is it because species of this sub-genus have not been found yet in this province? In our opinion this hypothesis is weakly sustained, as the number of surveys carried out in the Neotropics is much higher than in other areas (Moraes et al 2004;Tixier et al 2008a;Tixier and Kreiter 2009). We could thus suggest other hypotheses as (i) species of this sub-genus did not colonize this province or (ii) have been extinct.…”

Rates of description of Phytoseiidae mite species (Acari: Mesostigmata): space, time and body size variations

“…Entling et al (2010) discussed other mechanisms to explain the spider body size pattern observed: starvation resistance, predation pressure, intraguild interference, phylogenetic relationships. The proportion of rare species is expected to be higher in the tropics (Price et al 1995); we can wonder if this is due to the smaller size of phytoseiids at those latitudes or to the fact that higher habitat diversity in the tropics favours speciation and the existence of rare species in rare habitats (endemism) (Gaston 2000;Meier and Dikow 2004;Mao and Colwell 2005;Tixier and Kreiter 2009). Tropical forests are characterized by diverse assemblages of plant and animal species compared to temperate forests.…”

“…Tropical forests are characterized by diverse assemblages of plant and animal species compared to temperate forests. In regards to the close relationships largely reported between phytoseiids and plant support (Karban et al 1995;Walter 1996;McMurtry and Croft 1997;Kreiter et al 2002;Tixier and Kreiter 2009), plant diversification in such areas could affect phytoseiid diversity and speciation, limiting gene flow. …”

“…Taxonomic inventories are the most fundamental processes in biogeographical and macro-ecological studies as well as in conservation biology. They play major roles in the determination of species richness patterns, delineation of species ranges, quantification of extinction risk and prioritization of conservation efforts in hot spot areas (Mora et al 2008;Tixier et al 2008;Tixier and Kreiter 2009). However, taxonomic knowledge is deficient especially for some arthropod families, including mites, despite their assumed much greater diversity than presently known (i.e.…”