Species richness patterns of tiger beetles (Coleoptera: Cicindelidae) were analyzed using a grid of 407 squares (137.5 km per side) across northwestern South America (Guyana, Venezuela, Colombia, Ecuador, Peru, Bolivia and western Brazil). Reliable data on species numbers were available for only 149 of the squares. Using a trend surface model (a model used to represent the mean of a spatial process by a polynomial function of spatial coordinates) as well as altitudinal relief and biogeographical influence for each square, we predicted the number of tiger beetle species likely to occur in intermediate squares for which no or unreliable data were available. The resultant spatial patterns of species richness were compared to similar analyses for temperate areas of North America. Intercontinental comparisons and a more complete pattern of species numbers in South America are useful in developing an understanding of general spatial patterns and in the environmental management of species richness.

This study examines the behavioural responses to ultrasound in 52 species from the family Cicindelidae using both tethered night and non-flight assays. Tethered flying tiger beetles respond to trains of bat-like ultrasonic pulses with a short-latency, multi-component behaviour. There was no variation in the nature of the behavioural responses regardless of geographical distribution or phylogenetic position. Lowest mean behavioural thresholds lie predominantly between 30 and 45 kHz. Sensitivity, however, varies widely, and several species do not respond at all in these assays. The lowest thresholds for responders are most often between 70 and 80 dB SPL. Almost all subgenera of North American tiger beetles in the genus Cicindela have at least some species with low-threshold acoustic behaviour. The single exception is the large subgenus Cicindela ln where all species are completely unresponsive or have very high thresholds. There was little relationship between habitat and responsiveness to ultrasound, but there is a strong correlation with seasonal activity - species with adults active in the spring and autumn tall in the subgenus Cicindela) do not show ultrasound-triggered behaviour whereas summer-active species generally do. Superimposing these data on a current phylogeny of the North American tiger beetles suggests that acoustic behaviour (and hearing) is a shared primitive trait among the taxa examined here and that there have been at least five independent losses of this character.

The total numbers of tiger beetles species known in 157 countries or subregions in the world are reported and updated, based on both published and unpublished information. Also reported are the numbers and rate of species endemic to each country and the species richness patterns (total surface in km2/number of species) of the individual countries considered. The most current publications providing new data or detailing the tiger beetles of a country or political region are provided as references. A comparison is made between the present rank order of the 30 countries with the highest number of recorded tiger beetle species and their rank order in 1992, as well as between currently known species numbers in each of the major biogeographical regions of the world and the numbers registered in 1992. These comparisons show considerable constancy in spatial patterns and reinforce the claim for taxonomic stability of tiger beetles and for their reliability for use, especially by non-scientific decision-makers in conservation policy and management plans.

Due to the structuring forces and large-scale physical processes that shape our biosphere, we often find that environmental and ecological data are either spatially or temporally-or both spatially and temporally-dependent. When these data are analyzed statistical techniques and models are frequently applied that were developed for independent data. We describe some of the detrimental consequences, such as inefficient parameter estimators, biased hypothesis test results, and inaccurate predictions, of ignoring spatial and temporal data dependencies, and we cite an example of adverse statistical results occurring when spatial dependencies were disregarded. We also discuss and recommend available techniques used to detect and model spatial and temporal dependence including variograms, covariograms, autocorrelation and partial autocorrelation plots, geostatistical techniques, Gaussian autoregressive models K functions, and ARIMA models, in environmental and ecological research to avoid the aforementioned difficulties.

SummaryA comparison of species richness patterns of butterflies and birds was made using data from two grids of squares (small squares 137.5 km on a side and large squares 275 km on a side) covering western North America. Using geostatistical procedures, we found that the spatial patterns of species richness of these two taxa were related. The influence of grain size on the strength of this relationship was investigated by analysing the two data sets. For both data sets, the number of butterfly species in a square was a statistically significant predictor of the corresponding number of bird species. However, cross‐validation techniques showed that the marginal improvement in prediction accuracy due to including butterflies as a predictor was greater in the large‐square data. We explored the effect of areal extent on cross‐taxon congruencies by investigating species richness patterns in four subsets of the small‐square data. In regions with smaller areal extent, the cross‐taxon congruence patterns were not substantially different from the pattern found in the full data set. Finally, using data‐splitting techniques, we explored the relationships between prediction accuracy of species richness, sample size, areal extent of the sample, and grain size.

Indicator species can be a valuable tool for conservation research. Their use has been divided in two categories: inventory studies and monitoring studies. Tiger beetles (Coleoptera: Cicindelidae) have been identified as appropriate indicators for inventory studies. Here we test their value as potential bioindicators for monitoring habitat degradation in Venezuela. We analyze the general habitat associations of 47 of the 51 species of this insect family known to occur in Venezuela. We also analyze the assemblage patterns of forest-floor dwelling species associated with contiguous forest patches of primary and secondary forest in two sites. At the family level, tiger beetles occupy most of the major habitat types of Venezuela, but individual species tend to be restricted to one or two habitats. Forest-floor species assemblages change significantly with the degree of forest disturbance, and each stage of disturbance is characterized by a particular subset of species. Species associated with intermediate levels of disturbance show larger habitat breadth than those located at the extremes of the spectrum. The results of this study provide evidence that supports the use of tiger beetles as bioindicators for monitoring the degradation and regeneration of tropical forests.

We used birds, butterflies, tiger beetles, mean annual precipitation, and spatial statistical models to investigate the applicability of using indicators of species richness for conservation planning on a continental scale. The models were applied to data collected on three grids of squares (each square 275 or 350 km on a side) covering North America, the Indian subcontinent, and Australia. We applied spatial statistical modeling techniques to determine the viability of using a single or multiple indicators to predict spatial patterns of species diversity of ecologically and phylogenetically unrelated taxa. Spatial models are optimal for these analyses because species data typically are not spatially independent, primarily owing to dispersion effects. Furthermore, spatial models can be used to predict species numbers in areas where no observed data are available. We found that the number of tiger beetle species is a useful indicator of the number of butterfly species in North America and of the number of bird species on the Indian subcontinent, but it is not so useful as an indicator of either the number of bird or butterfly species in Australia or of the number of bird species in North America. We also found that the number of butterfly species is a useful indicator of the number of bird species in North America and Australia and that mean annual precipitation is useful for predicting the number of butterfly species in Australia. Although the general model used on all three continental areas is the same, the relative importance of potential indicators in predicting spatial patterns of other taxa changes from continent to continent. We attribute this change largely to differential biogeographical and ecological history, which must be taken into account in the selection and testing of potential indicators. Patrones Globales de Riqueza de Especies: Modelos Especiales para la Planificación de la Conservación Usando Datos de Bioindicadores y Precipitación En este estudio utilizamos aves, mariposas, escarabajos tigre, la precipitación media anual y modelos estadísticos espaciales para investigar la utilidad de los indicadores biológicos de riqueza de especies para la planificación, a escala continental, de la conservación. Los modelos estadísticos se aplicaron a datos obtenidos en cuadrículas (cada cuadrado con 275 o 350 km de lado) que abarcaban Norte América, el Subcontinente de India y Australia. Los modelos estadísticos espaciales permiten determinar la viabilidad del uso de indicadores simples o múltiples para predecir patrones espaciales de riqueza de especies ecológica o filogenéticamente no relacionadas. Los modelos espaciales son óptimos para este tipo de análisis debido a que los datos de las especies no son independientes del espacio donde éstas se encuentran, debido básicamente al efecto de la dispersión. Estos modelos también son utilizados para predecir el número de especies en áreas donde no hay datos disponibles. Los resultados mostraron que el número de especies de escarabajos tigre es un indicador útil de la diversidad de mariposas en Norte América y de aves en el Subcontinente de India, pero no es tan útil como indicador de aves y mariposas en Australia ni de aves en Norte América. El número de especies de mariposas es un indicador útil de las aves en Norte América y Australia. La precipitación es útil para predecir las mariposas en Australia. Aunque el modelo general utilizado en las tres áreas continentales es el mismo, la importancia relativa de los indicadores potenciales para predecir patrones de distribución espacial de otros taxones varía según el continente. Este variación se atribuye principalmente a diferencias en la historia biogeográfica y ecológica. Estas diferencias deben ser consideradas cuando se prueban los indicadores potenciales.

We apply geostatistical modeling techniques to investigate spatial patterns of species richness. Unlike most other statistical modeling techniques that are valid only when observations are independent, geostatistical methods are designed for applications involving spatially dependent observations. When spatial dependencies, which are sometimes called autocorrelations, exist, geostatistical techniques can be applied to produce optimal predictions in areas (typically proximate to observed data) where no observed data exist. Using tiger beetle species (Cicindelidae) data collected in western North America, we investigate the characteristics of spatial relationships in species numbers data, First, we compare the accuracy of spatial predictions of species richness when data from grid squares of two different sizes (scales) are used to form the predictions. Next we examine how prediction accuracy varies as a function of areal extent of the region under investigation. Then we explore the relationship between the number of observations used to build spatial prediction models and prediction accuracy. Our results indicate that, within the taxon of tiger beetles and for the two scales we investigate, the accuracy of spatial predictions is unrelated to scale and that prediction accuracy is not obviously related lo the areal extent of the region under investigation. We also provide information about the relationship between sample size and prediction accuracy, and, finally, we show that prediction accuracy may be substantially diminished if spatial correlations in the data are ignored.

General spatial patterns of species richness can be useful when determining conservation policy. Reliable species distribution data, however, are often rare or limited to a relatively few taxa in many parts of the world, and extensive species inventories tend to be expensive and time consuming. Consequently, the use of a few rigorously selected bioindicator taxa to represent broad-based inventories has been suggested as a viable alternative. Because spatial dependencies (spatial autocorrelations) are likely to exist in species richness data, common statistical techniques that assume independence are inappropriate for making cross-taxa comparisons of species ranges and distributions. We applied geostatistical methods that incorporate spatial dependencies to test the usefulness of a proposed bioindicator, tiger beetles, as a predictor of an unrelated taxon, butterflies, across North America and found a statistically significant relationship. We also showed how the application of statistical procedures that assume independence may be misleading. Finally, we showed how to make spatial predictions of species richness in intermediate areas where no sample species data are available.

Male tiger beetles continue to ride in amplexus on the backs of females after copulation. In scrub forest of peninsular India, the duration of this post-copulatory behavior was significantly different among five syntopic, congeneric species. Field and laboratory tests showed generally that males were present in the mating area at a higher proportion than females and that males remained mounted on females significantly longer when another male was present than when pairs were alone. These results are consistent with the interpretation of this amplexus as mate guarding. Four tests of comparative behavioral and ecological conditions were then used to explain the differential duration of amplexus observed among these co-occurring tiger beetle species: operational sex ratios, harassment and potential displacement of mating pair by unmated males, duration of female stay in mating area following copulation, and distance between mating area and oviposition site. Species differences in duration of female stay in the mating area after copulation and to a lesser degree operational sex ratios predicted amplexus duration for three of the species. The distance between mating area and oviposition site predicted the amplexus duration of the final two species. Probability of disruption by unmated males and frequency of male displacement during mating had little or no relation to any of the species differences in amplexus duration.

Introducing greater objectivity to selection of indicator taxa produces results that are likely to reduce uncertainty, be more efficiently obtained and more clearly communicated. Seven criteria are presented that can be used to objectively test the claim that a given taxon is an ideal indicator: (i) well known and stable taxonomy; (ii) well known natural history; (iii) readily surveyed and manipulated; (iv) higher taxa broadly distributed geographically and over a breadth of habitat types; (v) lower taxa specialized and sensitive to habitat changes; (vi) patterns of biodiversity reflected in other related and unrelated taxa; and (vii) potential economic importance. These criteria have different priorities depending on which of two general categories of biodiversity the indicator taxon is to be used. Monitoring places an emphasis on sensitivity to habitat change, and inventory places an emphasis on systematics. An index is suggested by which the results of selecting an indicator taxon can be more accurately communicated. This index is based on the number of criteria that are successfully tested for the proposed indicator and their priority.

The family of tiger beetles (Cicindelidae) is an appropriate indicator taxon for determining regional patterns of biodiversity because (1) its taxonomy is stabilized; (2) its biology and general life history are well understood, (3) individuals are readily observed and manipulated in the field, (4) the family occurs world‐wide and in a broad range of habitat types; (5) each species tends to be specialized within a narrow habitat; (6) patterns of species richness are highly correlated with those of other vertebrate and invertebrate taxa; and (7) the taxon includes species of potential economic importance. Logistical advantages provide some of the strongest arguments for selecting tiger beetles as an appropriate indicator taxon. Species numbers of tiger beetles are relatively well known for 129 countries. Eight countries alone account for more than half the world total of 2028 known species. Species numbers are also indicated for eleven biogeographical zones of the world. For gridded squares across North America, the Indian subcontinent, and Australia, species richness of tiger beetles, birds, and butterflies shows significant positive correlations. However, tiger beetle species numbers can be reliably determined within fifty hours on a single site, compared to months or years for birds or butterflies, and the advantage of using tiger beetles in conservation biology is evident

Previous experiments have shown many tiger beetle populations are limited by food, and prey size is directly related to mandible length (chord). To determine if world-wide patterns of non-random species co-occurrence exist, mandible length ratios were measured for co-occurring species in 32 assemblages of tiger beetle species in India, Indonesia, Kenya, Latin America, North America, and Papua New Guinea

Rates of water loss/gain for third instar larvae of the tiger beetle Cicindela marutha Dow were measured at various temperatures and humidities. The larvae occupy burrows in exposed hot, dry sand ridges. They are active at the surface at midday during spring and fall, but plug their burrows during the summer day and become active only at night. Water loss rates increase moderately with increasing temperatures (25 to 40°C) and show a consistent decline with increasing relative humidity (0 to 97·5%). The larvae do not absorb sufficient atmospheric moisture at any of the high humidities to offset water lost via transpiration; however, they ingest moist sand while burrowed and absorb the water from their digestive tract. This uptake mechanism supplements water obtained from prey, whose availability is limited, and also enables them to remain in positive water balance during times that microclimatic conditions prevent them from feeding on the surface.

Tiger beetles as a family show a broad spectrum of morphological, behavioral and physiological mechanisms by which their enemies are deterred. This phenomenon of multiple anti-predator mechanisms is also evident within species and individuals. Although multiple anti-predator mechanisms have been widely recognized among most if not all insects groups, general models and broad theoretical studies of predator-prey interactions have largely ignored this confounding pattern. Based on experiments and observations of tiger beetles, six theories are presented that explain the evolution of multiple anti-predator characters: 1) several characters must operate in concert to minimize predation, 2) each anti-predator character is largely or uniquely targeted against one of several distinct foraging phases used by the predator, 3) increasingly potent lines of defense may be used as a predator overcomes the primary ones, 4) separate anti-predator characters are directed at each of several different types of predator, 5) an individual prey is the result of a phylogenetic or ontogenetic accumulation of anti-predator characters, and 6) competing or counterselective forces may override or supplement the effectiveness of some anti-predator characters.

The Indian subcontinent has one of the most diverse tiger beetle faunas in the world. A combination of dispersal and vicariant events together with biotic and abiotic ecological factors are used to interpret present-day patterns of distribution and diversity. Within the single genus, Cicindela (sensu lat.), 150 species occur on the subcontinent, and all but thirty-five species in the subgenus Jansenia are interpreted as relatively recent arrivals from the Palaearctic (55%), China-Malaysia (32%) or Africa (9%). Endemism and unique ecological and habitat specialization are associated with the long-term presence of species of Jansenia, ancestors of which probably were present on the Greater Indian plate when it separated from Madagascar and Africa and rafted across the Tethys Sea to collide with the Asian mainland during the Oligocene 20 million years

The defensive compounds produced by pygidial glands of adult tiger beetles were analyzed for 83 species from North America, India, and Peru. Benzal-dehyde, the most common defensive compound detected, was found in 39 species. The presence of this compound, which has evolved independently in only a few other arthropod groups, indicates a cyanogenic precursor. Each of these 83 tiger beetle species occurred primarily in one of seven distinct habitats, such as forest floor, sand dune, water edge, and saline flat. All 83 species were also grouped according to genitalic similarities into distinct systematic taxa that represent closely related species. We predicted two alternative patterns of benzaldehyde presence among these tiger beetle species. (1) Through historical influences of systematic relatedness, benzaldehyde should be either present or absent nonrandomly among closely related species regardless of habitat and associated ecological similarities and differences. (2) Through convergence of defense against similar predators within each habitat type, benzaldehyde should be present nonrandomly among species in some habitats and absent nonrandomly in others, regardless of geographical location and systematic relationship. Our results show that in systematic groups with four or more species analyzed, 34 of 39 pooled species were consistent within a group for the presence or absence of benzaldehyde, regardless of habitat type (P < 0.001). However, for only one of the seven habitats (sandy water edge) was benzaldehyde present nonrandomly regardless of geographical location and systematic relationship. We conclude that historical (phylogenetic) factors are likely to be generally important in interpreting ecological data, as either alternative or interactive processes.

The thermal ecology of 13 tiger beetle species (Cicindela) was studied in the Sulphur Springs Valley of SE Arizona, USA. For each species, thoracic temperature (Tb) extremes for activity were determined in the laboratory and compared to Tb at which various behavioral activities occurred voluntarily in the field. Tb for coordinated walking showed few significant differences among species for lethal maximum (LTs) values (47.2-48.9°C) but considerable differences for mean minimum values (14.421.2°C). Field measurements showed significant differences among species for mean Tb while foraging. These means were correlated with laboratory measurements of mean minimum Tb for coordinated walking but not with LT50 maximum. The extreme difference in species mean minimum Tb for activity is best interpreted as a mechanism for temporal and spatial separation of species that minimizes predation and simultaneous use of limiting resources. The significance of the general similarity in species LT50 maximum thoracic temperature for activity is less obvious, but it is likely a convergent adaptation to thermally extreme habitats. It may have facilitated the species' historical dispersal abilities through thermally similar habitats over broad geographical areas and enhanced such factors as egg and larval development times.