Figure 5.1: Relative diversity of spiders in Makalali Private Game Reserve as represented by soil moisture, presence of north-facing slopes, Strychnos madagascariensis - Combretum. Figure 5.5a& b: (a) actual measured diversity and predicted diversity of spiders in Makalali Private Game Reserve. Colored dots correspond to the diversity found in the country.
What is Biodiversity?
Perhaps the greatest value of life's diversity may be the opportunities it gives us to adapt to change. Species diversity refers to the diversity of living species both in terms of the number of species and their relative abundance. Ecosystem diversity refers to the variety of ecological processes present in ecosystems in terms of habitats, biotic communities and ecological.
Loss of Biodiversity and Extinction
Diversity can be defined by the following general types: alpha (o), beta ((3) and gamma (y). The alpha component refers to the diversity within the habitat. This is a measure of the number of species that occur within an area of Management sound conservation depends increasingly on sound knowledge of species biology and dynamics (New 1995).
The status of invertebrate diversity
Likewise, future biodiversity inventories need to be designed around the use of efficient sampling and estimation procedures, particularly in. The potential use of spiders for modeling biodiversity has been highlighted by Downie et al.
Spiders in South Africa
The best known feature of the African savanna fauna is the diversity and biomass of large mammals. Savannas are important in the South African context because they are the basis of the African livestock and ecotourism industry, making it a valuable contribution to the formal economy.
Study site: Makalali Private Game Reserve
The five habitat types sampled in the reserve included mopane forest, rock outcrop and the three mixed scrubland types. Artificial water points have been created in the reserve, some of which are supplied by borehole water, especially during the dry winter months.
The focus of the current study
INTRODUCTION
Cost efficiency and effectiveness sampling techniques
Other factors considered important for a technique to be effective were the total number of individuals, species, number of unique species and number of different families sampled by each technique. Determination of the number of species sampled per hour assessed the effectiveness of the various techniques.
Data analysis
An effective method would be one that samples the majority of adults, allowing identification down to the species level. Other important factors taken into account for efficiency were the repeatability of the technique, the cost of the equipment required for the technique and the time investment required for sorting the samples.
RESULTS
Again, while sweeping yields the highest number of individuals, the number of families represented is the lowest. The efficiency of the different methods (expressed as the number of species captured per hour) was then calculated by dividing the number of species sampled by each method by the number of man-hours required to complete the 40 sites. Swiping was the most efficient method, followed by active search. successes and pitfalls.
DISCUSSION
One of the obvious biases of this method is its tendency to favor species that disperse easily (Sutherland 1996). However, increasing trap size would also increase catches of non-target invertebrates (Brennan et al. 1999).
CONCLUSION
This is because pitfall catches are representative of the activity of the spiders, which is influenced by the structure of the environment; direct comparisons between different habitats are therefore not possible as they only reflect the relative activity of individuals (Russell-Smith 1999). In addition, there are biases associated with each technique and the researcher should be aware of them in interpreting the results.
Biodiversity of spiders (Araneae) at Makalali Private Game Reserve
INTRODUCTION
The four selected sampling techniques (sweeping, knocking, active searching and potholes) were done at all sites throughout the reserve (40 in total). ), early summer (October-November 1999) and mid-summer (December 1999). Euclidean distances were the parameters chosen. The analysis was first done using families and then species present in the different sites.
RESULTS
- Functional groups and families
Whitmore - Spider Biodiversity 54 . bushveld) and lowest in habitat type 4 (rocky outcrops) (Figure 3.3a). Richness was highest in habitat type 3 (brown sandy bushveld) and lowest in habitat type 5 (mopane forests) (Figure 3.3b). ST ATISTICA was used to generate dendragrams from presence-absence data for families and species. The analysis at family level revealed three main clusters (Figure 3.8a). Nests were observed outside the sampling area. This particular group was simply not adequately sampled due to its patchy distribution and not because the species is rare. The theraphosids (baboon spiders) were sampled from all five different habitat types, but in low abundance (only 15 individuals were found in the entire reserve).
CONCLUSION
Caution should be exercised when interpreting the significance of differences between arthropod diversity indices, as not all species were sampled. There was some indication from the species accumulation curve that the number of new species discovered after each new sampling period was decreasing, but the full number of species had not yet been reached. The four samples taken from the river area further confirm the fact that they are not all species, as five new species were found in this habitat alone. Given the great diversity of spiders in this reserve, efforts must continue to ensure the conservation of the area not only for large vertebrates (which attract a lot of attention), but also for invertebrates.
INTRODUCTION
- Higher taxa as surrogates for species richness
More recent attention has focused on the development of indicators of biodiversity, particularly in relation to estimates of species richness in highly diverse groups, such as invertebrates, where comprehensive species-level surveys are usually not possible (Hammond 1990; Oliver & Beattie 1996; Andersen 1997; Rodriguez, Pearson & Barrera 1998). The emphasis was on the estimates of species richness and not on the naming of taxa. The aim of this study was to determine whether the species richness surrogates (indicators, higher taxa and morphospecies) used were reliable for biodiversity studies, using spiders as an example.
METHODS
This study attempts to determine whether non-specialists, with minimal training, could produce accurate estimates of the number of spider species contained in samples, where accuracy is determined by a taxonomic specialist. Thomisids are just one of the highly diverse spider families, and to make the results more generalizable, another diverse family, namely jumping spiders (Salticidae), was also evaluated for their utility as indicators of spider diversity. Dippenaar-Schoeman. The two levels of identification made it possible to test the accuracy of this method as a surrogate for species richness.
RESULTS
- Morphospecies identified by non-specialists as surrogates for species richness
However, at the family level the number of species was significantly more overestimated than at the genus level. Genera (X) and families (0) are compared. The genders most closely approximate the 450 angle (dotted line) which means they are better substitutes. Means and 95% confidence limits are shown. N represents the number of places ranked by each participant.
DISCUSSION
Gaston & Blackburn (1995) point out that the strength of the correlation between the number of species and higher taxa is likely to decline rapidly to increasingly higher taxonomic levels (e.g. from genera to tribes to families; Williams & Gaston 1994). Beattie 1993). The data also suggest that the use of morphospecies requires a minimum of unambiguous morphological characters that a relatively untrained individual can use easily and quickly. McGeoch (1998) also indicates that the quality of the data used to make bioindicator and conservation predictions is fundamental to their accuracy. Slotow & Hamer (2000) also discourage the use of morphospecies, especially for conservation planning.
CONCLUSION
- Patterns vs processes
A richness and evenness index was also calculated, but only the diversity index was used in this current analysis. The diversity was. A backward stepwise multiple regression analysis was used to determine the best combination of biotic and abiotic factors affecting the diversity of the four levels. The variables assessed in the models are listed in table 5.1. Computerized GIS maps of topography, vegetation and hydrology were produced. The significant factor maps derived from the multiple regression models were then.
RESULTS
Variables that explain the diversity of plant wandering spider diversity are presented in Table 5.5. Variables that are excluded from this model include soil density, soil acid saturation, clay, south, west and Ziziphusmucronata - Combretum hereeroense under closed forest vegetation type. All maps of significant variables from the descriptive model were superimposed to produce a predicted diversity map for the Reserve. The map calculator function in ArcView was used and the following regression equation was used for spider diversity:Y (spider diversity)=. Spielers were not positively affected by the presence of prey. Game availability may not be.
DISCUSSION
The web of Cyclosa (wasteline spiders) is usually built in bushes and is common in open woodland (Filmer 1991). The stabilimentum often consists mainly of the prey animals that are attached in a vertical line to the center of the web. Philodromids were widespread in the reserve, occurring in all habitat types and 90% of the sites sampled. The genera found in the reserve are distributed as follows. Interestingly, they were not found in any of the sites sampled, but were collected as additional samples around the reserve. The genera sampled from the reserve are found in the following Afrotropical regions: Anyhops: Cameroon, Somalia, Central and South Africa; Selenops: throughout the Afrotropical region, including Comoros, Seychelles (Dippenaar-Schoeman&.
Two genera were found in the reserve, Leucauge (silver spiders) and Nephila (golden orb spiders). The Nephila species was widely distributed throughout the park, while the Leucauge spp. Theraphosids were quite widely distributed, occurring in all habitat types and at 38% of all sampled locations. The genera sampled from the reserve occur in the following Afrotropical regions: Brachionopus: South Africa; Ceratogyrus: Southern Africa;.
I Mines
Appendix 5.3: The vegetation density of (a) trees < 1 m and (b) trees > 2 m at Makalali Private Game Reserve.
