Rainforest ants of the Tiwi Islands: a remarkable centre of endemism in Australia’s monsoonal tropics

Andersen, Alan N.; Houadria, Mickal; Berman, Maïa; Geest, M. van der

doi:10.1007/s00040-012-0238-6

Cited by 7 publications

(4 citation statements)

References 24 publications

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“…The rainforest ant fauna of the AWT has very strong South-East Asian affinities, and contrasts sharply with that of adjacent open sclerophyll habitats, which are dominated by autocthonous, arid-adapted taxa [ 66 – 68 ]. The AWT fauna includes several South-East Asian-based genera that occur nowhere else in Australia, as well as many others whose distributions elsewhere in Australia are restricted to rainforest patches further south along the eastern coast or west in the monsoonal zone [ 69 , 70 ]. A large proportion of the species remain undescribed; for example, a recent revision of the predominantly rainforest genus Myrmecina increased the number of described Australian species from 2 to 13 [ 71 ].…”

Section: Methodsmentioning

confidence: 99%

Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

et al. 2016

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The threat of anthropogenic climate change has seen a renewed focus on understanding contemporary patterns of species distribution. This is especially the case for the biota of tropical mountains, because tropical species often have particularly narrow elevational ranges and there are high levels of short-range endemism. Here we describe geographic patterns of ant diversity and distribution in the World Heritage-listed rainforests of the Australian Wet Tropics (AWT), revealing seasonal moisture stability to be an important environmental correlate of elevational patterns of species composition. We sampled ants in leaf litter, on the litter surface and on tree trunks at 26 sites from six subregions spanning five degrees of latitude and elevation ranges from 100–1,300 m. A total of 296 species from 63 genera were recorded. Species richness showed a slight peak at mid elevations, and did not vary significantly with latitude. Species composition varied substantially between subregions, and many species have highly localised distributions. There was very marked species turnover with elevation, with a particularly striking compositional disjunction between 600 m and 800 m at each subregion. This disjunction coincides with a strong environmental threshold of seasonal stability in moisture associated with cloud ‘stripping’. Our study therefore provides further support for climatic stability as a potential mechanism underlying patterns of diversity. The average height of orographic cloud layers is predicted to rise under global warming, and associated shifts in seasonal moisture stability may exacerbate biotic change caused by rising temperature alone.

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Section: Methodsmentioning

confidence: 99%

Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

et al. 2016

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“…Similarly, much of the woody flora from Neotropical savannas have sister groups in more ancient vegetation types such as moist and seasonally dry tropical forests (Simon & Pennington, ; Simon et al., ). Finally, many ants of Neotropical savannas are widespread forest species that extend into semi‐arid habitats (Leal et al., in press), which is in strong contrast to the dichotomous composition of forest and savanna ant faunas in Australia (Andersen, Houadria, Berman, & van der Geest, ; Reichel & Andersen, ; van Ingen et al., ) and South Africa (Slingsby, ). Patterns of savanna ant diversity in relation to rainfall remain undocumented in the Neotropics, but marked declines with increasing aridity have been predicted due to the forest affinities of the fauna (Andersen et al., ).…”

Section: Introductionmentioning

confidence: 99%

Neotropical savanna ants show a reversed latitudinal gradient of species richness, with climatic drivers reflecting the forest origin of the fauna

Vasconcelos

Maravalhas

Feitosa

et al. 2017

Journal of Biogeography

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Aim: To evaluate the extent to which ant species richness in Neotropical savannas varies with macrogeographic variables, and to identify the potential climatic drivers of such variation. Location:The Cerrado savanna biome of central Brazil, in a region spanning ca. 20°o f latitude and 18°of longitude.Methods: Standardized sampling of the arboreal and ground-dwelling faunas was performed in 29 well-preserved savanna sites using pitfall traps. Species were classified according to their habitat affinities: open-savanna specialists, forest-associated species or habitat generalists. We used generalized linear models to evaluate the importance of geographic (latitude, longitude and elevation) and climatic (mean temperature and three metrics of rainfall) variables as predictors of species richness.Results: The total number of species recorded at each site varied more than twofold (from 59 to 144), and latitude was the best geographic correlate of overall species richness. However, contrary to the expected pattern, more species were found at higher than lower latitudes. This reversed latitudinal pattern of diversity occurred for both the arboreal and ground-dwelling faunas, and for the habitat generalists and forest specialists. The savanna specialists showed a mid-latitudinal peak in diversity. Overall, there was a significant positive association between rainfall and species richness, but the strength of this relationship varied with ant habitat affinity.Main conclusions: The Cerrado ant fauna shows a reverse latitudinal gradient in species diversity, and this can be explained by increasing rainfall during the warmest months of the year (and therefore in plant productivity) with increasing latitude.The sensitivity of Cerrado ant diversity to declining rainfall contrasts with the high resilience to aridity of the Australian savanna ant fauna, and this reflects the contrasting evolutionary histories of these faunas. Our findings highlight the importance of historical processes as drivers of intercontinental contrasts in macroecological patterns. K E Y W O R D Sant communities, Cerrado, latitudinal diversity gradient, Neotropical arid diagonal, species diversity, tropical savanna

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“…Small (typically <5 ha) patches of monsoonal rainforest are dotted throughout the landscape, occurring where spring‐fed moisture is available throughout the year or where there is long‐term topographic protection from fire (Russell‐Smith, ). The ant fauna of these forests provides a dramatic contrast with that of the surrounding savanna—the arid‐adapted elements are largely absent, and many shade‐tolerant taxa of Indo‐Malayan origin occur (Reichel & Andersen, ; Andersen et al ., , ).…”

Section: Methodsmentioning

confidence: 99%

Diversity and biogeography of a species‐rich ant fauna of the Australian seasonal tropics

2016

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Although ants are an ecologically dominant and extensively studied faunal group throughout the tropics, there is a poor understanding of tropical ant diversity and distribution at large spatial scales. Here we use a collection developed from 3 decades of ant surveys to present the first analysis of ant diversity and biogeography of a large tropical region. Our objective was to document the species richness, composition, and biogeographic distributions of the ant fauna of the 400 000 km "Top End" of Australia's Northern Territory. The known Top End ant fauna comprises 901 native species from 59 genera. The richest genera are Pheidole (90 species), Melophorus (83), Monomorium (83), Camponotus (71), Meranoplus (63), Polyrhachis (57), Rhytidoponera (50), Tetramorium (43), Cerapachys (32), and Iridomyrmex (31). The fauna is the center of diverse radiations within species-groups of genera such as Meranoplus, Rhytidoponera, and Leptogenys. It also includes IndoMalayan species that have likely bypassed the normal dispersal route into Australia through Cape York Peninsula in North Queensland. Faunistic similarity with other regions of far northern Australia is associated more with rainfall than with geographic proximity. Most (60%) of Top End ant species have not been recorded elsewhere, and, despite uncertainties relating to species delimitation and sampling intensity, this appears to be a credible estimate of the level of endemism. Such exceptionally high endemism can be attributed to the Top End's geographic isolation from other regions of northern Australia with comparably high rainfall.

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Rainforest ants of the Tiwi Islands: a remarkable centre of endemism in Australia’s monsoonal tropics

Cited by 7 publications

References 24 publications

Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

Ant Diversity and Distribution along Elevation Gradients in the Australian Wet Tropics: The Importance of Seasonal Moisture Stability

Neotropical savanna ants show a reversed latitudinal gradient of species richness, with climatic drivers reflecting the forest origin of the fauna

Diversity and biogeography of a species‐rich ant fauna of the Australian seasonal tropics

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