Biodiversity of Ant: A case study of Madagascar
Biodiversity of Ant: A case study of Madagascar
Insects constitute 85% of the world’s animal biodiversity and deserve increased attention in regions of the world, such as Madagascar(Graoomridge 1992)(Fisher and Robertson, 2002), where species-rich habitats are under threat. Although invertebrates and plants make up the vast majority of species in forest habitats land scape level patterns of invertebrate biodiversity are little known for tropical ecosystem. Such distributional data will largely determine how effective conservation areas are at representing district assemblages of specis. Species richness, the number of species in a given area is the currency of biodiversity but for most groups, we lack knowledge of how to inventory species(Fisher 1999).
Conservation methods that prioritize areas based on diversity patterns (species richness and l0cal endemism) of birds and mammals and do not include insect diversity overlook most organism and thus do not guarantee preservation of the greatest diversity. Pearson and Cassola showed that for dridded squares 275 km on a side, across North America the Indian subcontinent, and Australia, species richness levels of tiger beetles, birds and butterflies were positively correlated. However there is evidence that vertebrate diversity is not an accurate indicator of invertebrate biodiversity. Predergast et al showed low overlap between highly diverse sites of butterflies, dragonflies, liverworts, aquatic plants and breeding birds in Britian. At 32 sites in southeastern Austrailia, Yen found no correlation between the number of species of vertebrates and beetles. Scharff conclude that sites in tropical rain forests of eastern Africa where linyphiid spiders showed the highest diversity were not necessarily the same as those documented for birfs, mammals amphibians and reptiles. Thus arthropod patterns of diversity ca not be assumed to correlated with those of vertebrates and methods are needed to quantify species richness and endemism in insect taxa. This is the reason for supporting inventory methodologies to survey leaf litter ant diversity along an elevational gradient.( Fisher, B.L. 1996, Fisher, B.L. 1997)
The first survey in 1996 involving in a combination of pitfall and leaf litter sampling showed there were 27.866 ants belong to 114 species and 28 genera and general collecting yield an additional 34 species at 4 sites in a 250m transect.(Fisher, 1999) Species accumulation curves demonstrate the efficacy of these techniques in sampling the majority of the ants in the leaf litter. The species collected and their relative abundance are presented. Species diversity decreased with elevation. Species turnover and faunal similarity measures showed a division in ant communities between the lowest elevation site and the highest elevation sits that corresponded to the cloud forest transition. This intensive study provided a unique basis studying how species composition and diversity change with elevation and latitude.
After 2 years, the second study collected and identified 24.586 ants belong to 189 species and 25 genera in d’ Anjanaharibe-Sub and 35 species in general collecting yielded. On the Masoala Peninsula, pitfall and leaf litter collections yielded 52.307 ant comprising 167 species and 25 genera, and 30 more species for general collected. Combination, there are a total of 325 species and 34 genera were collected. For each elevation, 2 different species richness estimators, incidence-based coverage estimator and first-order jackknife, gave comparable results. Species accumulation curves approached an asymptote and demonstrated the efficacy of these inventory techniques. Species collected and their relative abundances are presented. Species richness peaked at midelevation. Species turnover and faunal similarity measures demonstrated a division in ant communities beteen lowland forest <= 875 m and montane fores >=1200m. A midelevation peak in species richness in argued to be the result of the mixing of two distinct, lower and montane forest ant assemblages.
The most recent research until now about the effects of elevational gradient is the third survey in 1999. There were 12.285 ants belonging to 25 genera and 11 species; an additional 28 species by general collecting. For each elevation 2 species richness estimators-incidence-based coverage estimator and first order jackknife gave comparable results. Species accumulation curves showed decreased rates of species detection and demonstrated the efficacy of these inventory techniques. Species turnover, complementarily and faunal similarity measures demonstrated a division in ant communities between lowland forest at <= 800 m and montane forest at 1250m. A mid-elevation peak in richness is probably the result of the mixing of two distinct, lower and montane forest, ant assemblages.
The increasing loss of biodiversity presents a daunting challenge to taxonomists and requires the discovery and analysis of biodiversity at a greatly accelerated pace. If we are really serious about “zero biodiversity loss” in Madagascar and elsewhere, then conservation planning needs to be based more fundamentally on biodiversity data, and this requires taxonomic knowledge. The renovation of systematics, as proposed here, is an extremely ambitious program requiring innovation, and large-scale application of tools in systematic research, from collecting to dissemination of results. In addition, this initiative requires the systematic community to work together at a level never before realized, focusing attention on global revision of select taxa and ensuring the repre-sentation of results in the conservation process, thereby enhancing the perceived value of taxonomy.
Groombridge, B., ed 1992.Global Biodiversity: statues of earth’s living resources. World Conservation Monitoring Centre. Chapman and hall. London.
Fisher, B.L. 1996. Ant diversity patterns along an elevational gradient in the Réserve Naturelle Intégrale d’Andringitra, Madagascar. Fieldiana: Zoology (n.s.) 85:93–108.
Fisher, B.L. 1997. Ant Diversity Patterns and Conservation Planning in Madagascar. Ph.D. Dissertation, University of California, Davis, USA. 241 pp.
Fisher, B. L., 1999. Improving inventory efficiency: A case study of leaf-litter ant diversity in Madagascar. Ecological Applications. 9, 714-731.
Fisher, B. L., Robertson, H. G., 2002. Comparison and origin of forest and grassland ant assemblages in the high plateau of Madagascar (Hymenoptera : Formicidae). Biotropica. 34, 155-167.
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