Samantha Stoffberg

Four New Bat Species (Rhinolophus hildebrandtii Complex) Reflect Plio-Pleistocene Divergence of Dwarfs and Giants across an Afromontane Archipelago

Gigantism and dwarfism evolve in vertebrates restricted to islands. We describe four new species in the Rhinolophus hildebrandtii species-complex of horseshoe bats, whose evolution has entailed adaptive shifts in body size. We postulate that vicissitudes of palaeoenvironments resulted in gigantism and dwarfism in habitat islands fragmented across eastern and southern Africa. Mitochondrial and nuclear DNA sequences recovered two clades of R. hildebrandtii senso lato which are paraphyletic with respect to a third lineage (R. eloquens). Lineages differ by 7.7 to 9.0% in cytochrome b sequences. Clade 1 includes R. hildebrandtii sensu stricto from the east African highlands and three additional vicariants that speciated across an Afromontane archipelago through the Plio-Pleistocene, extending from the Kenyan Highlands through the Eastern Arc, northern Mozambique and the Zambezi Escarpment to the eastern Great Escarpment of South Africa. Clade 2 comprises one species confined to lowland savanna habitats (Mozambique and Zimbabwe). A third clade comprises R. eloquens from East Africa. Speciation within Clade 1 is associated with fixed differences in echolocation call frequency, and cranial shape and size in populations isolated since the late Pliocene (ca 3.74 Mya). Relative to the intermediate-sized savanna population (Clade 2), these island-populations within Clade 1 are characterised by either gigantism (South African eastern Great Escarpment and Mts Mabu and Inago in Mozambique) or dwarfism (Lutope-Ngolangola Gorge, Zimbabwe and Soutpansberg Mountains, South Africa). Sympatry between divergent clades (Clade 1 and Clade 2) at Lutope-Ngolangola Gorge (NW Zimbabwe) is attributed to recent range expansions. We propose an “Allometric Speciation Hypothesis”, which attributes the evolution of this species complex of bats to divergence in constant frequency (CF) sonar calls. The origin of species-specific peak frequencies (overall range = 32 to 46 kHz) represents the allometric effect of adaptive divergence in skull size, represented in the evolution of gigantism and dwarfism in habitat islands.

Molecular phylogenetics and historical biogeography of Rhinolophus bats.

The phylogenetic relationships within the horseshoe bats (genus Rhinolophus) are poorly resolved, particularly at deeper levels within the tree. We present a better-resolved phylogenetic hypothesis for 30 rhinolophid species based on parsimony and Bayesian analyses of the mitochondrial cytochrome b gene and three nuclear introns (TG, THY and PRKC1). Strong support was found for the existence of two geographic clades within the monophyletic Rhinolophidae: an African group and an Oriental assemblage. The relaxed Bayesian clock method indicated that the two rhinolophid clades diverged approximately 35 million years ago and results from Dispersal Vicariance (DIVA) analysis suggest that the horseshoe bats arose in Asia and subsequently dispersed into Europe and Africa.

Correlated genetic and ecological diversification in a widespread southern African horseshoe bat.

The analysis of molecular data within a historical biogeographical framework, coupled with ecological characteristics can provide insight into the processes driving diversification. Here we assess the genetic and ecological diversity within a widespread horseshoe bat Rhinolophus clivosus sensu lato with specific emphasis on the southern African representatives which, although not currently recognized, were previously described as a separate species R. geoffroyi comprising four subspecies. Sequence divergence estimates of the mtDNA control region show that the southern African representatives of R. clivosus s.l. are as distinct from samples further north in Africa than they are from R. ferrumequinum, the sister-species to R. clivosus. Within South Africa, five genetically supported geographic groups exist and these groups are corroborated by echolocation and wing morphology data. The groups loosely correspond to the distributions of the previously defined subspecies and Maxent modelling shows a strong correlation between the detected groups and ecoregions. Based on molecular clock calibrations, it is evident that climatic cycling and related vegetation changes during the Quaternary may have facilitated diversification both genetically and ecologically.

The Divergence of Echolocation Frequency in Horseshoe Bats: Moth Hearing, Body Size or Habitat?

A phylogenetic approach was used to test three hypotheses regarding the evolution of diversity in the echolocation frequencies used by horseshoe bats (family Rhinolophidae, genus Rhinolophus): 1) Allotonic Frequency Hypothesis (high frequency echolocation in the Rhinolophidae resulted from coevolution with moth hearing); 2) Allometry Hypothesis (echolocation frequency is negatively scaled with body size and evolutionary changes in echolocation frequencies are correlated with changes in body size in the Rhinolophidae); and 3) Foraging Habitat Hypothesis (evolution of echolocation frequency is associated with changes in habitat type). Both discrete and continuous character sets were used for ancestral state reconstructions and for investigating patterns of evolution between frequency and body size, and frequency and habitat type. Contrary to the prediction of the Allotonic Frequency Hypothesis, echolocation frequency in the Rhinolophidae did not increase over time, which would be expected if moth hearing and bat echolocation frequency coevolved. The number of extant species that exhibit calls within moth hearing ranges was not significantly different from the number of species that echolocate outside of moth hearing range. There was also no correlation between changes in frequency and changes in habitat type as predicted by the Foraging Habitat Hypothesis. Instead, the evolution of echolocation frequency within the Rhinolophidae was correlated with changes in body size as predicted by the Allometry Hypothesis.

A recent inventory of the bats of Mozambique with documentation of seven new species for the country

The bat fauna of Mozambique is poorly documented. We conducted a series of inventories across the country between 2005 and 2009, resulting in the identification of 50 species from 41 sites. Of these, seven species represent new national records that increase the country total to 67 species. These data include results from the first detailed surveys across northern Mozambique, over an area representing almost 50% of the country. We detail information on new distribution records and measurements of these specimens. Special attention is paid to the Rhinolophidae, because these include several taxa that are currently in a state of taxonomic confusion. Furthermore, we also present some notes on taxonomy, ecology and echolocation calls. Finally, we combine modelled distributions to present predicted species richness across the country. Species richness was lowest across the coastal plain, to the east and far north, and is predicted to increase in association with rising altitude and higher topographic unevenness of the landscape.

Diversity of Hipposideridae in the Mount Nimba massif, West Africa, and the Taxonomic Status of Hipposideros lamottei

Several species complexes exist within the African representatives of the genus Hipposideros and the relationships between these taxa are not yet well understood. We present evidence showing that at least seven species of Hipposideros co-occur at Mount Nimba at the northern boundary of the Upper Guinean forest zone. The species H. lamottei has been misdiagnosed previously, partly as a result of errors in published measurements. This taxon is currently known only from high-altitude grasslands in northern (Guinean) Mount Nimba. Cytochrome b sequences and echolocation calls of this species, as well as for H. marisae, are presented for the first time. Also, at least two different species groups, previously lumped in H. ruber, co-exist syntopically here. Mount Nimba apparently represents a diversity hotspot for species of Hipposideros in West Africa, and as a result may be an important site for their conservation.

Field identification of two morphologically similar bats, Miniopterus schreibersii natalensis and Miniopterus fraterculus (Chiroptera: Vespertilionidae)

Miniopterus schreibersii natalensis and Miniopterus fraterculus are two morphologically similar, but genetically distinct, species of insectivorous bat that, more often than not, share roosts. Identifying these two species in the field is difficult because of an overlap in the ranges of both forearm and mass. We thus attempted to find morphological features that could be used to distinguish between these two species in the field. We compared cranial and external morphological measurements from museum specimens of the two species, using principal component analysis and discriminant function analysis, to determine which variables could be used to discriminate between them. Length of the hind foot and total body length were identified as the variables responsible for most of the variation between these two species. Miniopterus s. natalensis has a longer total body length (113.6 ± 3.5 mm) than M. fraterculus (102.2 ± 4.8mm)but a relatively shorter hind foot (9.1 ± 0.6 mm, 9.8 ± 0.8 mm, respectively). A function generated from standardized canonical variables, (HF × 0.279417) – (TL × 0.989306) + 100, and based on length of hind foot (HF) and total body length (TL) generated function scores <0 for M. s. natalensis and +0 for M. fraterculus. On the basis that positive values (above zero) indicated M. fraterculus, and negative values (below zero) indicated M. s. natalensis, we were able to correctly assign 20 individuals to their respective species using the above function. These individuals were previously identified as M. fraterculus or M. s. natalensis from their mtDNA sequences. The function thus provides a useful tool for discriminating between the two species in the field.

Rhinolophus capensis (Chiroptera: Rhinolophidae)

Abstract Rhinolophus capensis Lichtenstein, 1823 is a medium-sized rhinolophid commonly called the Cape horseshoe bat. It has a characteristic horseshoe-shaped nose leaf that surrounds its nostrils but does not cover the entire muzzle. This species is endemic to South Africa and is typically found in caves along the coastal parts of Northern, Western, and Eastern Cape provinces. It is a gregarious species that is often found roosting with R. clivosus and Miniopterus schreibersii natalensis. From a conservation standpoint, R. capensis has been listed as vulnerable until recently, when its listing was changed to near threatened.

Bats of Southern and Central Africa: A Biogeographic and Taxonomic Synthesis

With their nocturnal and often secret habits, bats may be one of the most misunderstood groups of animals, yet worldwide they comprise over 1100 species (Simmons 2005), some 20% of all mammals. Their rich taxonomic and ecological diversity is attributed to their ability to fly and echolocate, enabling them to exploit most nocturnal niches. Because bats are relatively inaccessible to people who do not study them scientifically, very few guides to their identification, distribution and biology exist: however, here we have a book that will appeal to both students of bats and the general public alike.