Resource partitioning among cape foxes,bat-eared foxes,and black-backed jackals in South Africa

Cape foxes (Vulpes chama) and bat-eared foxes (Otocyon megalotis) are sympatric with black-backed jackals (Canis mesomelas) over much of southern Africa, although competition with and/or predation by jackals may suppress local populations of both fox species. From 2005 to 2008, we captured, radio-collared, and monitored 11 cape foxes, 22 bat-eared foxes, and 15 black-backed jackals on a game ranch in South Africa to investigate their spatial, habitat, temporal, and dietary resource overlap. Mean annual home-range sizes were 27.7 km² for cape foxes, 5.0 km² for bat-eared foxes, and 17.8 km² for jackal family groups. Home ranges overlapped completely between species, although core areas overlapped less (<45%), with cape foxes and jackals overlapping the least (12%). When active, cape foxes, but not bat-eared foxes, used core areas of jackal groups less than expected. Additionally, both fox species used jackal core areas less than expected for their den sites, suggesting areas outside jackal core areas were used as refuges by foxes. Strong levels of habitat partitioning were not apparent at the study site or home-range levels, although habitat selection for den sites differed between jackals and cape foxes. Jackals were the most diurnal across seasons, whereas cape foxes were the most nocturnal. Diets overlapped little (R₀ = 0.20–0.34) among the canid species, with bat-eared foxes overlapping the least with the others. Jackals killed at least 5 collared bat-eared foxes and 1 collared cape fox, indicating potential interference competition, probably for exclusive use of territorial space rather than over shared resources. We conclude that bat-eared foxes coexisted with jackals primarily by their dietary specialization and group living. Cape foxes coexisted with jackals by exhibiting high levels of spatial, habitat, temporal, and dietary partitioning. Surprisingly, the fox species exhibited positive associations with each other. Our results show the mechanisms that may allow jackals to suppress fox populations, yet also show how foxes, in turn, use different mechanisms to coexist with a dominant canid. © 2012 The Wildlife Society.     

Canine carnassials: character displacement in the wolves, jackals and foxes of Israel

Previous research implies that competitive character displacement in felids and mustelids of Israel is expressed by canine size. Anatomy and observed killing behaviour of canids suggest that canines in this group are less adapted for the stylized role they play in felids and mustelids. Thus we hypothesized that character displacement, if it exists in canids, should not be manifested more clearly by canine size than by other traits. Five sympatric and at least partially syntopic canids occupy Israel, while in North Africa the largest (wolf) and smallest (Blanford's fox) are absent. Sexual size dimorphism in Israeli canids is generally less than in felids and mustelids (in which we analysed each sex as a separate ‘morphospecies’), so we used mixed-sex samples to represent each species. The three largest species (wolf, golden jackal and red fox) are also represented by Middle Palaeolithic samples in Israel, and all three had larger carnassial lengths then. Carnassial lengths, canine diameters and skull lengths are all remarkable evenly spaced among the five recent species in Israel. In Egypt, no trait manifests significant equality. Despite regional fluctuations in size, the carnassial length ratios of the three smaller species (foxes) are strikingly constant (1.18–1.21) throughout the region, while the ratios for the three larger species (wolf, jackal and red fox), sympatric only in Israel, are larger (1.33–1.34). Finally, mean carnassial length of jackals is constant across North Africa, while skull length and canine diameter both increase from Algeria through Egypt. All three traits are larger in Egypt than in Israel. We tentatively ascribe the equal ratios in Israel to competitive character displacement, though this hypothesis is speculative because of numerous lacunae in knowledge of diet, killing behaviour, available resources and extent of food limitation. Furthermore, humans have greatly affected range, density and ecology of wolves and jackals in the last century. Larger sizes in the Palaeolithic may well be manifestations of Bergmann's rule. The constancy of carnassial length in North African jackals, notwithstanding a longitudinal cline in CBLs of these populations, and the constant ratio between jackal and red fox carnassial length are both consistent with a hypothesis of character release in the absence of the wolf.     

Food niche separation between four sympatric Namib Desert carnivores

The diet of four sympatric carnivore species was established by analyzing scats collected during 1978-1980, a period of increasing drought in the Namib Desert. Termites were especially important in the diet of Aardwolves and Bat-eared foxes and the food spectrum was not broadened in response to increased aridity. Black-backed jackals utilized a wide range of prey items, especially rodents and lagomorphs, while the Cape fox largely depended on murid rodents, but also took lagomorphs and insects. Separation in use of space and times of activity between the four species also occurred.     

Deep divergence among mitochondrial lineages in African jackals

Recently, molecular analyses revealed that African and Eurasian golden jackals are distinct species. This finding suggests re‐investigation of the phylogenetic relationships and taxonomy of other African members of the Canidae. Here, we provide a study on the phylogenetic relationship between populations of African jackals Lupulella mesomelas and L. adusta inferred from 962 bp of the mitochondrial cytochrome b (cytb) gene. As expected from its disjunct distribution, with one population in eastern Africa and the other one in southern Africa, we found two mitochondrial lineages within L. mesomelas, which diverged about 2.5 million years ago (Ma). In contrast, in L. adusta with its more continuous distribution in sub‐Saharan Africa, we found only a shallower genetic diversification, with the exception of the West African population, which diverged around 1.4 Ma from the Central and East African populations. Both divergence ages are older than, for example the 1.1–0.9 million years between the grey wolf Canis lupus and the African golden wolf C. lupaster. One taxonomic implication of our findings might be that the two L. mesomelas populations warrant species status. However, genome‐wide data with adequate geographical sampling are needed to substantiate our results.     

Molecular evidence of an African Phiomorpha-South American Caviomorpha clade and support for Hystricognathi based on the complete mitochondrial genome of the cane rat (Thryonomys swinderianus)

The complete mitochondrial genome of an African cane rat, Thryonomys swinderianus (Rodentia, Hystricognathi), was included in a phylogenetic analysis along with 4 rodents, 14 additional eutherians, and 3 noneutherian outgroups. Monophyly of the suborder Hystricognathi, represented by the cane rat and the South American guinea pig, Cavia porcellus, was strongly supported by maximum-parsimony, neighbor-joining, and maximum-likelihood methods. The molecular-based estimate of the divergence time of Old and New World Hystricognathi (approximately 85 million years before present, MYBP) is consistent with an hypothesis of vicariance divergence due to the rifting of the African and South American continents 86-100 MYBP. Monophyly of Rodentia or the superordinal clade Glires (Rodentia and Lagomorpha) were not supported.     

Molecular and morphological circumscription of Mesocestoides tapeworms from red foxes (Vulpes vulpes) in central Europe

Here we examine 3157 foxes from 6 districts of the Slovak Republic in order to determine for the first time the distribution, prevalence and identity of Mesocestodes spp. endemic to this part of central Europe. During the period 2001-2006, an average of 41.9% of foxes were found to harbour Mesocestoides infections. Among the samples we confirmed the widespread and common occurrence of M. litteratus (Batsch, 1786), and report the presence, for the first time, of M. lineatus (Goeze, 1782) in the Slovak Republic, where it has a more restricted geographical range and low prevalence (7%). Using a combination of 12S rDNA, CO1 and ND1 mitochondrial gene sequences together with analysis of 13 morphometric characters, we show that the two species are genetically distinct and can be differentiated by discrete breaks in the ranges of the male and female reproductive characters, but not by the more commonly examined characters of the scolex and strobila. Estimates of interspecific divergence within Mesocestoides ranged from 9 to 18%, whereas intraspecific variation was less than 2%, and phylogenetic analyses of the data showed that despite overlapping geographical ranges, the two commonly reported European species are not closely related, with M. litteratus more closely allied to North American isolates of Mesocestoides than to M. lineatus. We confirm that morphological analysis of reproductive organs can be used to reliably discriminate between these often sympatric species obtained from red foxes.     

Evolutionary ecomorphology of the Falkland Islands wolf Dusicyon australis

The Falkland Islands wolf Dusicyon australis is an extinct canid that was once the only endemic terrestrial mammal to inhabit the Falkland Islands. There is still a puzzling picture of the morphological adaptations of this wolf that quickly evolved from its mainland fossil ancestor: Dusicyon avus. We employ a geometric morphometric approach to identify patterns of skull shape variation in extant canids and Dusicyon spp. The Falkland Islands wolf and its fossil ancestor show a more carnivorous feeding morphology than other South American foxes, and they cluster morphologically with jackals. This supports convergence in skull shape between Dusicyon and Old World canids, although the convergence is not as strong as that exhibited by their sister hyper‐ and hypocarnivorous taxa.     

African-derived mitochondria in South American native cattle breeds (Bos taurus): evidence of a new taurine mitochondrial lineage

This article reports the nucleotide diversity within the control region of 42 mitochondrial chromosomes belonging to five South American native cattle breeds (Bos taurus). Analysis of these data in conjunction with B. taurus and B. indicus sequences from Africa, Europe, the Near East, India, and Japan allowed the recognition of eight new mitochondrial haplotypes and their relative positions in a phylogenetic network. The structure of genetic variation among different hypothetical groupings was tested through the molecular variance decomposition, which was best explained by haplotype group components. Haplotypes surveyed were classified as European-related and African-related. Unexpectedly, two haplotypes within the African cluster were more divergent from the African consensus than the latter from the European consensus. A neighbor-joining tree shows the position of two haplotypes compared to European/African mitochondrial lineage splitting. This different and putatively ancestral mitochondrial lineage (AA) is supported by the calibration of sequence divergence based on the Bos-Bison separation. The European/African mitochondria divergence might be subsequent (67,100 years before present) to that between AA and Africans (84,700 years before present), also preceding domestication times. These genetic data could reflect the haplotype distribution of Iberian cattle five centuries ago.     

Recent speciation between sympatric Tanganyikan cichlid colour morphs

Lake Tanganyika, Africa's oldest lake, harbours an impressive diversity of cichlid fishes. Although diversification in its radiating groups is thought to have been initially rapid, cichlids from Lake Tanganyika show little evidence for ongoing speciation. In contrast, examples of recent divergence among sympatric colour morphs are well known in haplochromine cichlids from Lakes Malawi and Victoria. Here, we report genetic evidence for recent divergence between two sympatric Tanganyikan cichlid colour morphs. These Petrochromis morphs share mitochondrial haplotypes, yet microsatellite loci reveal that their sympatric populations form distinct genetic groups. Nuclear divergence between the two morphs is equivalent to that which arises geographically within one of the morphs over short distances and is substantially smaller than that among other sympatric species in this genus. These patterns suggest that these morphs diverged only recently, yet that barriers to gene flow exist which prevent extensive admixture despite their sympatric distribution. The morphs studied here provide an unusual example of active diversification in Lake Tanganyika's generally ancient cichlid fauna and enable comparisons of speciation processes between Lake Tanganyika and other African lakes.     

An intraspecific comparative analysis of character divergence between sympatric species

Although sympatric character divergence between closely related species has been described in a wide variety of taxa, the evolutionary processes responsible for generating these patterns are difficult to identify. One hypothesis that can explain sympatric differences is ecological character displacement: the sympatric origin of morphologically divergent phenotypes in response to selection caused by interspecific competition. Alternatively, populations may adapt to different conditions in allopatry, with sympatric distributions evolving through selective colonization and proliferation of ecologically compatible phenotypes. In this study, I characterize geographic variation within two sibling species of rocky-shore gastropods that have partially overlapping distributions in central California. In sympatry, both Nucella emarginata and N. ostrina show significant differences in shell shape and shell ornamentation that together suggest that where the two species co-exist, divergent phenotypes arose as an evolutionary consequence of competition. To examine the evolutionary origins of divergent characters in sympatry, I used a comparative method based on spatial autocorrelation to remove the portion of the phenotypic variance among populations that is explained by genetic distance (using mitochondrial DNA sequences and allozyme frequency data). Because the remaining portion of the phenotypic variance represents the independent divergence of individual populations, a significant sympatric difference in the corrected dataset provides evidence of true character displacement: significant sympatric character evolution that is independent of population history. After removal of genetic distance effects in Nucella, shell shape differences remain statistically significant in N. emarginata, providing evidence of significant sympatric character divergence. However, for external shell ornamentation in both species and shell shape in N. ostrina, the significance of sympatric differences is lost in the corrected dataset, indicating that colonization events and gene flow have played important roles in the evolutionary history of character divergence in sympatry. Although the absence of a widely dispersing planktonic larva in the life cycle of Nucella will promote local adaptation, the results here indicate that once advantageous traits arise, demographic processes, such as recurrent gene flow between established populations and extinction and recolonization, are important factors contributing to the geographic pattern of sympatric character divergence.     

Social organization,survival, and dispersal of cape foxes (Vulpes chama) in South Africa

We monitored 20 cape foxes (Vulpes chama) to determine the social organization, survival, and dispersal of this species on two sites in South Africa from 2005 to 2008. Cape foxes were socially monogamous and territorial, with annual home ranges of mated pairs (n = 8) overlapping 80% on average, compared to a mean overlap of 3% between foxes in adjacent ranges. At least 2 pairs remained associated for >1 breeding season, and both sexes exhibited strong site fidelity, as home ranges in consecutive years overlapped 58–98%. Members of mated pairs never foraged together, however they used the same or nearby (<100 m apart) day rests 81% of the time when pups were 0–4 months of age, but only 28% of the time during other months of the year. Dispersal was male biased, as all juvenile males (n = 6) dispersed when 9–11.5 months old, whereas 3 of 4 juvenile females remained philopatric as either breeders or non-breeding associates. At least 6 foxes bred as yearlings (3 F, 3 M), indicating cape foxes have high reproductive potential. Two adult females maintained their territories after their mates died, whereas two adult males dispersed soon after their mates died, indicating cape foxes likely have a female-based social organization. Annual survival was 0.64, and predation from larger carnivores, primarily black-backed jackals (Canis mesomelas), was responsible for 71% of mortalities. Our results provided empirical support for previous hypotheses regarding the relationship between body size and life-history patterns in Canidae, as several ecological parameters of cape foxes were similar to that of other small (<6 kg) canid species, especially Vulpes species inhabiting arid and semi-arid environments.     

Presence of antibotulinum neurotoxin antibodies in selected wild canids in Israel

Serum samples from 35 golden jackals (Canis aureus syriacus), eight wolves (Canis lupus), and four red foxes (Vulpes vulpes) from various regions of Israel were collected during the years 2001-04 and tested for antibodies to Clostridium botulinum neurotoxin (BoNT) types C and D. Antibodies against BoNT types C and D were detected in 10 (29%) and in 3 (9%) of 35 golden jackals, respectively, using enzyme-linked immunosorbent assay. This report describes detection of anti BoNT antibodies in wild canids other than coyotes (Canis latrans) for the first time and demonstrates that C. botulinum type C is prevalent in Israel.     

A striking example of the founder effect in the mollusc Littorina saxatilis

Two South African populations of Littorina saxatilis were examined by starch-gel electrophoresis at 16 enzyme loci and compared with 13 populations of North Atlantic saxatilis from both American and European coasts, and with six British populations of the closely related species Littorina arcana. The South African animals showed a severely reduced heterozygosity (– 0.052) compared with Atlantic populations of saxatilis ( = 0.181), and the mean genetic distance between the two areas was high ( = 0.203) compared with distances within the North Atlantic saxatilis populations (D = 0.034). In fact, the saxatilis from South Africa were genetically more distant from the North Atlantic samples of L. saxatilis than were the arcana from British shores. The reduced genetic heterozygosity and genetic divergence of the South African populations is attributed to founder effects following a postulated recent introduction by man.     

Divergence in the calling songs between sympatric and allopatric populations of the southern wood cricket Gryllus fultoni (Orthoptera: Gryllidae)

In the eastern United States the wood cricket Gryllus fultoni (Orthoptera: Gryllidae) occurs in sympatry with G. vernalis in an area between eastern Kansas and west of the Appalachian Mountains. Calling songs were recorded from 13 sympatric and allopatric localities. Both field and laboratory recordings showed that chirp rate (CR) and pulse rate (PR) overlapped extensively between allopatric populations of G. fultoni and sympatric populations of G. vernalis; by contrast, there was little or no overlap in these variables between sympatric populations of these two species. Divergence in PR and CR between the two species was thus greater in areas of sympatry than in areas of allopatry. Our field and laboratory studies of G. fultoni calling songs thus demonstrate the pattern expected of character displacement and support the genetic assumptions of this hypothesis. Other possible explanations for the sympatric divergence such as ecological character displacement and clinal variation are discussed.     

Character shifts in the defensive armor of sympatric sticklebacks

Natural enemies may contribute to the morphological divergence of sympatric species, yet their role has received little attention to date. We tested for character shifts in defensive armor of sympatric threespine sticklebacks (Gasterosteus aculeatus complex) previously shown to exhibit ecological character displacement in traits related to resource use. We scored five defensive armor traits in sympatric benthic and limnetic stickleback species from southwestern British Columbia and compared them with the same traits in nearby allopatric populations in the presence of the same predatory fish (Oncorhynchus sp.). This approach is analogous to tests of ecological character displacement that compare trophic traits of sympatric and allopatric species in the presence of the same community of resource types. Three patterns consistent with character displacement in defensive armor were found. First, limnetics in different lakes had consistently more armor than sympatric benthics. Second, the average amount of armor, averaged over both species, was reduced in sympatry compared to allopatric populations. This reduction was almost entirely the result of shifts by benthic species, whereas armor in limnetics was more similar to that in allopatric populations. Third, differences between sympatric benthics and limnetics in total armor were greater than expected from comparisons with allopatric populations. We interpret these patterns as the result of differences in habitat-specific predation regimes accompanying ecological character displacement and indirect interactions between sympatric stickleback species mediated by their top predators. These results suggest that predation may facilitate, rather than hinder, the process of divergence in sympatry.     

Analysis of character divergence along environmental gradients and other covariates

Character displacement is typically identified by comparing phenotypic differences in sympatry and allopatry. Recently, however, Goldberg and Lande (2006) pointed out that when phenotypic characters vary along an environmental gradient, the standard approach may fail to identify sympatric character divergence. Here we present a general analytical procedure for identifying sympatric character divergence while accounting for phenotypic changes that covary with environmental variables. Our approach uses residual randomization from a generalized linear model, and allows the statistical comparison of sympatric phenotypic divergence to allopatric phenotypic divergence while accounting for phenotypic variation along a gradient. Through simulation we demonstrate that our approach correctly identifies patterns of sympatric character divergence when they are present, and does not identify such patterns when they are not. Our analytical approach complements and extends the suggestions of Goldberg and Lande (2006), by allowing a full statistical assessment of the varied patterns of character displacement along environmental gradients, or while accounting for other covariates and sources of variation.     

Molecular differentiation at nuclear loci in French host races of the European corn borer (Ostrinia nubilalis)

French populations of the European corn borer consist of two sympatric and genetically differentiated host races. As such, they are well suited to study processes that could be involved in sympatric speciation, but the initial conditions of host-race divergence need to be elucidated. Gene genealogies can provide insight into the processes involved in speciation. We used DNA sequences of four nuclear genes to (1) document the genetic structure of the two French host races previously delineated with allozyme markers, (2) find genes directly or indirectly involved in reproductive isolation between host races, and (3) estimate the time since divergence of the two taxa and see whether this estimate is compatible with this divergence being the result of a host shift onto maize after its introduction into Europe approximately 500 years ago. Gene genealogies revealed extensive shared polymorphism, but confirmed the previously observed genetic differentiation between the two host races. Significant departures from the predictions of neutral molecular evolution models were detected at three loci but were apparently unrelated to reproductive isolation between host races. Estimates of time since divergence between French host races varied from approximately 75,000 to approximately 150,000 years, suggesting that the two taxa diverged recently but probably long before the introduction of maize into Europe.     

Genetic characterization of populations of the golden jackal and the red fox in Israel

The golden jackal and red fox are among the wildlife species protected by Israeli law as enforced by the Israel Nature and Parks Authority. In 1964, as a part of a management program to control rabies in Israel, a poison eradication campaign was launched to exterminate golden jackals, considered to be the main reservoir of the disease. The program resulted in the near-complete extermination of jackals in Israel, while foxes were only mildly affected. Jackals have since regained their original numbers and have recolonized southern Israel. We here examined the population structure of the golden jackal and red fox in Israel, 48 years after the poison eradication campaign. DNA from 88 golden jackals and 89 red foxes representing five different geographic regions was extracted and amplified at 13 microsatellite loci in order to characterize the populations on a genetic level. High genetic diversity was found among the jackal and fox populations. A possible migration route through the Jordan Rift Valley was suggested for both species by the genetic similarity of populations in northern and southern Israel. However, in both species, the animals from the center of Israel were distinctive from those north or south, indicating the relative isolation of central populations, likely due to fragmentation or a high abundance of food resources. Genetic profiles obtained for the golden jackal and the red fox in Israel may aid in their conservation management and in the study of zoonotic diseases.     

Large Spatial Scale of the Phenotype-Environment Color Matching in Two Cryptic Species of African Desert Jerboas (Dipodidae: Jaculus)

We tested the camouflage hypothesis, or the linkage between animal (Saharan rodent) and habitat coloration, on the largest geographical scale yet conducted. We aimed to determine whether phenotypic variation is explained by micro-habitat variation and/or genetic polymorphism to determine 1) the strength of linkage between fur color and local substrate color, and 2) the divergence in fur coloration between two genetic clades, representing cryptic species, throughout the complete range of the African desert jerboas (Jaculus jaculus). We used a combination of museum and field-collected specimens, remote sensing tools, satellite and digital photography and molecular genetic and phylogenetic methods to investigate the above hypotheses. Along with showing that the two divergent genetic clades of jerboas occur sympatrically throughout their African distribution, we showed significant covariation between dorsal fur coloration of the animals and the color of their habitat. We also described significant phenotypic divergence in fur color, consistent with genetic divergence between the sympatric clades. The linkage between environment and phenotype supports the idea that the selection promoting cryptic coloration is persistent in contemporary populations of jerboas, however the phenotypic divergence indicates that it has different strengths (or optima) in the two clades. The mosaic distribution of micro-habitats occupied by geographically sympatric clades suggests that it may influence both ecological and evolutionary dynamics between these two cryptic species.     

Trophic ecology of two savanna grazers,blue wildebeest <Emphasis Type="Italic">Connochaetes taurinus</Emphasis> and black wildebeest <Emphasis Type="Italic">Connochaetes gnou</Emphasis>

The feeding niches and trophic ecology of two South African grazers, blue wildebeest Connochaetes taurinus and black wildebeest Connochaetes gnou, are compared using stable carbon and nitrogen isotope data from feces and tooth dentine collagen. As sympatric, closely related taxa predicted to occupy similar trophic positions, the blue and black wildebeest provide a good model for studying the mechanisms of coexistence and macroevolution in mammals. Data from feces collected from a single reserve in the Free State Province reveal different trophic behaviors between two herds of blue wildebeest and between both compared with a single herd of black wildebeest. These data suggest that sympatric coexistence of blue and black wildebeest is facilitated by differential niche occupation at family group or herd levels, rather than between species. However, such separation does not occur over longer time scales: results from dentine collagen support the hypothesis that the two species are indistinct in terms of trophic behavior, although blue wildebeest show more feeding flexibility, probably because of their wider habitat tolerance range. Similarities in premaxillary width of males and females of both species also suggest that both species are adapted to similar feeding styles. Thus, it is unlikely that changes in trophic behavior provided the trigger for divergence of the black from the blue wildebeest lineage in the Middle Pleistocene. We argue that the case of these two species represents an example of speciation that was not driven by resource competition, as is often assumed for many turnover events in mammalian evolution. We briefly discuss a previous suggestion that links black wildebeest evolution to their more territorial breeding behavior associated with Middle-to-Late Pleistocene landscape changes in southern Africa.