Capensis Population Research Articles

Eelgrass Zostera capensis populations in KwaZulu-Natal, South Africa, harbour distinct genomic signals despite limited geographical distance

Seagrasses are threatened by anthropogenic stressors and climate change, with numerous population declines reported. In South Africa, the eelgrass Zostera capensis is restricted to estuarine environments and has a disjunct distribution and declining status. With the majority of the distribution of Z. capensis on the west and southwest coasts of South Africa, the isolated easternmost populations in KwaZulu-Natal Province (KZN) are of particular interest. Following the extirpation of Z. capensis at Durban and St Lucia, only five populations remain, of which three (in the Amatikulu, Mlalazi and Mhlatuze estuaries) are situated <50 km apart. Previous molecular analyses showed strong population structure between Z. capensis populations, but the geographically close populations on the east coast were not included. In this study, using single nucleotide polymorphisms (SNPs) isolated from 31 individual sampled plants collected from three northern KZN estuaries, we provide evidence for distinct population clusters, with unique evolutionary signals. Zostera capensis in the Mlalazi Estuary has a low level of genomic diversity, likely as a result of a small, dynamic population unable to withstand prolonged freshwater exposure. Our results suggest that conservation efforts need to consider unique population signals even among geographically close populations, in particular within the context of restoration, where genomic compatibility may determine the persistence of restored populations.

Phylogeny of Holocacista capensis (Lepidoptera: Heliozelidae) from Vineyards and Natural Forests in South Africa Inferred from Mitochondrial and Nuclear Genes

In South Africa, the family Heliozelidae in the order Lepidoptera is restricted to four known species. The grapevine leaf miner, Holocacista capensis, feeds between the epidermal layers of a grapevine leaf, predominantly along the leaf margin. A final instar larva will descend from the blotch mine/gallery to attach its cocoon casing (constructed from the epidermal layers of the mined gallery) to any object below the infested leaf. Five monophyletic clades and a polyphyletic group have been identified within the Heliozelidae, using a mitochondrially encoded gene cytochrome c oxidase I (COI) and a nuclear gene, histone 3 (H3). An exploratory study of the genetic diversity within H. capensis populations was conducted using these genes. The phylogenetic analyses of COI indicate that H. capensis that are currently being collected from South Africa fall within three clades/haplotypes, of which one is well supported and contains only one species from Gauteng, and one has three specimens from two different areas in the Western Cape province, while 80% belong to haplotype 1 (H1). The current study can be used as a starting point for future DNA-based studies aimed at gaining insight into possible patterns of diversity in H. capensis to confirm switching from native to commercial grapevine hosts. However, more samples need to be collected from different areas in South Africa.

Mammal diversity of an urbanised environment in an arid zone of south-west Africa

Thorough investigation of the entire mammalian assemblages has not been hitherto conducted in any African city. Most studies were limited to single species causing problems to citizens or to small mammals causing health hazard. In 2011–2020, 81 mammal species were recorded in Windhoek, the capital of Namibia, although only 34 (42.0%) species occurred in the inner zone of the city (50 sq. km). The most speciose (25 species) order were rodents. Within this order the most speciose was the family Muridae (n = 13 species), while the most common rodent species were: Rhabdomys pumilio, Mastomys coucha, Gerbilliscus leucogaster, and Gerbillurus paeba. The second most speciose group of mammals were Chiroptera represented by 14 (17.3%) species in the outer zone (650 sq. km) and 8 species (23.5%) in the inner zone. Ungulates, although mostly rare or uncommon, were in the outer zone represented by eight (9.9%) species. None was, however, recorded in the inner zone. Nineteen Carnivora species (23.5%) were recorded in the outer zone, but only two of them in the inner zone. Other species recorded in Windhoek were representatives of seven other orders: Eulipotyphla (n = 4 spp.), Macroscelidea (n = 3), Lagomorpha (n = 3), Hyracoidea (n = 1), Primates (n=2), Tubulidentata (n = 1), and Pholidota (n = 1). Two species, Cynictis penicillata and Geosciurus inauris, were found to be relatively common in the inner zone. They have reached a population density (5.6 and &gt;2.0 individuals per 100 ha, respectively) higher than in any other cities in Namibia, and probably in southern Africa at large. Despite intense searching in the inner zone, Hystrix africeaustralis and Procavia capensis were only recorded in a shrubby hill. The Procavia capensis population was estimated at 40–70 individuals. A few troops of Papio ursinus are resident only in the outer zone. The following species recorded in Windhoek are in the IUCN Red List of Threatened Species: Acinonx jubatus, Panthera pardus, Felis nigripes, Hyaena brunnea, and Smutia temminckii. Noteworthy is the absence of any alien mammal species in the inner zone, and the presence of only Mus musculus in the outer zone of the city. The protection of mammals in Windhoek, especially in the outer zone, may act as a catalyst to move the municipality governance towards a more effective biodiversity conservation.

Apis mellifera capensis larvae show low resistance to a highly virulent Paenibacillus larvae field strain

American foulbrood (AFB) poses a serious threat to honey bees worldwide. Clinical signs of AFB were first detected in South Africa in 2008 and are currently confined to the Western Cape, an area inhabited by A. m. capensis. The virulence of isolated AFB field strains and the resistance of A. m. capensis larvae to these field strains were investigated. We individually infected larvae in full-sized A. m. capensis colonies with different doses of the ERIC I, subtype Ab field strain of P. larvae identified from colonies in the Western Cape and assessed larval mortality over 14 days. We compared larval mortality in colonies from a previously AFB-exposed A. m. capensis population to larval mortality in colonies from a non-AFB exposed population. The field strain tested was highly virulent, with the LD50 found to be less than a single spore per larva in both populations, with there being no statistical difference between the populations in larval mortality rates. Our results indicate that once infected with AFB, both A. m. capensis populations responded similarly to the infection and the larvae from both populations showed low resistance to AFB. This indicates that the limited impact of AFB throughout Africa is not due to the direct resistance of larvae to AFB infection, but rather to other factors such as colony-level resistance resulting from highly developed hygienic behaviour, the dispersed nature of beekeeping in Africa, and the swarming/absconding nature intrinsic in African honey bees.

Contrasting phylogeographic patterns of intertidal mites (Acari, Oribatida) along the South African shoreline

The South African coast is known to harbor four different species of intertidal oribatid mites and their distribution strongly correlates with marine ecoregions. Relatively little is known about the dispersal of these organisms and how populations of different locations are connected. To test dispersal abilities and connectivity of these South African species, we performed a morphometric and molecular genetic study. COI gene sequences of two of the widely distributed South African intertidal oribatid mite species revealed clearly contrasting patterns. Halozetes capensis, which occurs in the Agulhas Ecoregion, shows distinct genetic structuring, whereas Fortuynia elamellata micromorpha, which is distributed in the Natal Ecoregion, exhibits gene flow between all populations. The paleoenvironmental history and specific ocean current pattern are suggested to be responsible for these patterns. During the last glacial maximum, the colder climate and the weakening of the Agulhas Current possibly resulted in a bottleneck in the warm-adapted F. e. micromorpha populations, but the subsequent global warming allowed the populations to expand again. The cold-adapted H. capensis populations, on the other hand, experienced no dramatic changes during this period and thus could persist in the Agulhas Ecoregion. Considering transport on ocean currents, the Agulhas Current could be further responsible for the connectivity between the Fortuynia populations. But the deflection of this current in the Agulhas Ecoregion could support the isolation of Halozetes populations. The concomitant morphometric study demonstrated morphological homogeneity among populations of Fortuynia and thus confirms strong connectivity. The Halozetes populations, on the other hand, form two different morphological groups not reflecting geography.

The impact of urbanization on outcrossing rate and population genetic variation in the native wildflower, Impatiens capensis

Abstract Cities are one of the fastest growing ecosystems on the planet, and conserving urban biodiversity is of primary importance. Urbanization increases habitat fragmentation and may be particularly problematic for native plant species which often exist in small, remnant populations in cities. We studied the effects of urbanization on Impatiens capensis, a self-compatible native wildflower, which is an important nectar and pollen source for native bees and hummingbirds. We sampled I. capensis from six populations located in urban and rural habitats in Toronto, Ontario, Canada. We sequenced the DNA of 43 families (N = 86 individuals) using genotype-by-sequencing to obtain 5627 single nucleotide polymorphisms. From each parent and offspring, we estimated individual outcrossing rates, population-level genetic diversity and genetic structure among populations. We found that 95% of plants were outcrossed, and populations were genetically differentiated, where urban populations contained a subset of the genetic variation found in rural populations. Urban populations exhibited lower genetic diversity than rural populations, and we detected a relationship between population census size and habitat on genetic diversity. Despite high outcrossing rates, our results suggest that urbanization reduces the genetic diversity of I. capensis populations, potentially increasing the vulnerability of these populations to long-term population declines and extirpation in response to urbanization.

An Assessment of Wakkerstroom Wetland and Its Vegetation Communities from 1938 to 2019

There are few studies on the size and changes in species composition over time for wetlands in South Africa. Techniques such as remote sensing have become popular in assisting the development of management plans due to their spatio-temporal advantages and easily reproducible vegetation and land cover maps. The Wakkerstroom wetland was examined using aerial photography to examine possible changes in the extent and Landsat imaging was used to map its vegetation communities. To assess the distribution of vegetation types on Wakkerstroom wetland, in situ recording of vegetation types and their GPS coordinates was conducted and a Random Forest model was used to predict vegetation types from Landsat pixel spectra across the wetland extent. As calculated from aerial photographs, the Wakkerstroom wetland has increased in extent by 0.483 km2 from 1938 to 2009. The P. australis population density increased significantly over time (r = 0.89), whereas the T. capensis population density had a strong negative correlation over time (r = -0.70). A strong negative relationship between P. australis and T. capensis existed (r = -0.88). A need exists to introduce a management tool that will create a greater mosaic of vegetation communities thus ensuring a greater bird, reptile, and amphibian diversity.

Morphological differences in a population of Rufous-collared Sparrow (Zonotrichia capensis, Statius Müller, 1776) (Passerine, Emberizidae) at different elevations in the Tropical Andes

Abstract Populations that breed along steep elevation gradients show diverse physiological and morphological changes in response to the different environmental conditions. The latter has been discussed by Bergmann’s and Allen’s ecogeographic rules about body and appendage sizes and environmental temperature. We compared morphometric measures (mass, bill width, tarsus, wing, and tail length) of a Zonotrichia capensis population in two localities at different elevations with similar latitudes and photoperiods on the western slope of the Colombian Central Andes. We compared a Low Elevation locality (LE) at 1800 m a.s.l. and a High Elevation locality (HE) at 3853 m a.s.l. that have approximate wind speeds of 1.3 m/s and 8.4 m/s, respectively. During 12 months of sampling, we captured 46 adults using mist-nets; 26 in the LE and 20 in the HE. Each individual was sexed using molecular techniques at the Laboratory of Genetics of the Department of Biological Sciences of Universidad de Caldas. Individuals (males + females) from the HE had longer wings and tails than those from the LE (F1,44 = 5.93; P = 0.019). Also, wings of males in the HE were longer than those of females in both localities and tails of males in the HE were longer than those of LE males. Our results did not agree with what was expected according to Allen’s and Bergmann’s ecogeographic rules. Longer wings and tails increase sustainment, maneuverability, and balance in low atmospheric pressures and strong air currents and these conditions are found at high elevation habitats. Most likely, the longer wings found for HE males allow greater movement during territorial behavior. Further, these differences in morphological traits along elevational gradients could result from micro-evolutionary changes between localities or phenotypic plasticity of individuals exposed to different environmental conditions.

Dietary Preferences in Relation to Food Availability during Spring Season for the Cape Hare Lepus capensis in Arid Areas

Abstract. In Africa, the Cape hare (Lepus capensis) population is under threat from multiple stresses. For its efficient conservation planning, it is crucial to provide comprehensive information on various ecological aspects. To this end, we assessed the dietary composition of the Cape hare in relation to food availability in the North Sahara Desert. The investigation was conducted in spring in three Tunisian National parks (i.e., Bouhedma, Sidi Toui, and Jbil) with typical arid and desert ecosystems. Food availability was estimated using the quadrat point approach for each park while diet composition was assessed using microhistological analysis of faecal samples. Results revealed that 19 of 98 plant species were consumed by Cape hares. Poaceae family, present in all three parks, was the primary source of food. Asteraceae and Brassicaceae were the next most preferred diets. Woody species were eaten but their proportion in the diet depended on the availability of herbaceous plants. Our results tend to show that Cape hares select high quality diet depending on the availability of food, but further studies across four seasons at different spatial scales may eventually lead to further information about these issues.

Spatial genetic diversity in the Cape mole-rat, Georychus capensis: Extreme isolation of populations in a subterranean environment.

The subterranean niche harbours animals with extreme adaptations. These adaptations decrease the vagility of taxa and, along with other behavioural adaptations, often result in isolated populations characterized by small effective population sizes, high inbreeding, population bottlenecks, genetic drift and consequently, high spatial genetic structure. Although information is available for some species, estimates of genetic diversity and whether this variation is spatially structured, is lacking for the Cape mole-rat (Georychus capensis). By adopting a range-wide sampling regime and employing two variable mitochondrial markers (cytochrome b and control region), we report on the effects that life-history, population demography and geographic barriers had in shaping genetic variation and population genetic patterns in G. capensis. We also compare our results to information available for the sister taxon of the study species, Bathyergus suillus. Our results show that Georychus capensis exhibits low genetic diversity relative to the concomitantly distributed B. suillus, most likely due to differences in habitat specificity, habitat fragmentation and historical population declines. In addition, the isolated nature of G. capensis populations and low levels of population connectivity has led to small effective population sizes and genetic differentiation, possibly aided by genetic drift. Not surprisingly therefore, G. capensis exhibits pronounced spatial structure across its range in South Africa. Along with geographic distance and demography, other factors shaping the genetic structure of G. capensis include the historical and contemporary impacts of mountains, rivers, sea-level fluctuations and elevation. Given the isolation and differentiation among G. capensis populations, the monotypic genus Georychus may represent a species complex.

Contrasting environments shape thermal physiology across the spatial range of the sandhopper Talorchestia capensis.

Integrating thermal physiology and species range extent can contribute to a better understanding of the likely effects of climate change on natural populations. Generally, broadly distributed species show variation in thermal physiology between populations. Within their distributional ranges, populations at the edges are assumed to experience more challenging environments than central populations (fundamental niche breadth hypothesis). We have investigated differences in thermal tolerance and thermal sensitivity under increasing/decreasing temperatures among geographically separated populations of the sandhopper Talorchestia capensis along the South African coasts. We tested whether the thermal tolerance and thermal sensitivity of T. capensis differ between central and marginal populations using a non-parametric constraint space analysis. We linked thermal sensitivity to environmental history by using historical climatic data to evaluate whether individual responses to temperature could be related to natural long-term fluctuations in air temperatures. Our results demonstrate that there were significant differences in the thermal response of T. capensis populations to both increasing/decreasing temperatures. Thermal sensitivity (for increasing temperatures only) was negatively related to temperature variability and positively related to temperature predictability. Two different models fitted the geographical distribution of thermal sensitivity and thermal tolerance. Our results confirm that widespread species show differences in physiology among populations by providing evidence of contrasting thermal responses in individuals subject to different environmental conditions at the limits of the species' spatial range. When considering the complex interactions between individual physiology and species ranges, it is not sufficient to consider mean environmental temperatures, or even temperature variability; the predictability of that variability may be critical.

The frequency of arrhenotoky in the normally thelytokous Apis mellifera capensis worker and the Clone reproductive parasite

In most honey bees, unfertilized eggs develop into haploid males via arrhenotokous parthenogenesis. The Cape honey bee (Apis mellifera capensis) is different. Although mated queens always produce females sexually, if workers lay unfertilized eggs the eggs develop into diploid females via thelytokous parthenogenesis. Thelytoky in A. m. capensis has given rise to an entirely clonal lineage of reproductive parasites that infests colonies of their neighbouring subspecies A. m. scutellata. The switch from arrhenotoky to thelytokous worker reproduction is thought to be determined by a recessive allele at a single locus. However, it has recently been shown that this simple phenotype/genotype association may be more complex because individuals from the parasitic clonal lineage produce c.a. 15 % of eggs arrhenotokously and 85 % of eggs thelytokously. Here, we investigate the fate of these arrhenotokous eggs and show that they can develop into adult males. We further show that workers of the sexual A. m. capensis population produce far fewer arrhenotokous eggs. We discuss possible evolutionary explanations for this difference.

Distribution, feeding behaviour, and condition of Cape horse mackerel early life stages, Trachurus capensis, under different environmental conditions in the northern Benguela upwelling ecosystem

AbstractEarly life history (ELH) traits are key to understand variable recruitment success and hence the stock size of marine fish. One of the currently most puzzling ecosystems in this regard is the northern part of the Benguela Current upwelling system off Namibia. Here, populations of the formerly dominant pelagic species, sardine and anchovy, failed to recover during the last three decades after a dramatic decline. In contrast, Cape horse mackerel, Trachurus capensis, maintained a constant population size. Warming of the system and shoaling of hypoxic zones together with feedback loops within an altered foodweb are discussed to be responsible for this regime shift. In this study, we address the role of larval traits for the successful performance of the T. capensis population under the present environmental conditions with the focus on feeding ecology. We investigated seasonal variations of the geographical distribution, growth rate, feeding ecology, and nutritional condition of their ELH stages and examined relationships with water temperature, dissolved oxygen concentration, and micro-zooplankton composition. T. capensis' ELH stages showed a wide spatial and seasonal distribution, a preference for higher water temperatures (18–21°C) and presence over a wide range of dissolved oxygen concentrations (0.13–6.35 ml O2 l−1). Feeding success was high and mainly different groups of Copepoda were targeted, which were strongly size selected. The high dietary importance of micro-copepods during large parts of the larval phase indicates successful exploitation of this food source, which has increased in abundance during the last decade. It also explains observed best nutritional conditions at temperatures between 18 and 21°C, since these small copepods are commonly associated with warmer temperatures. Altogether, these traits enhance the species' probability to encounter suitable environments for the survival of their ELH stages, which is likely to lead to their high recruitment success in the northern Benguela ecosystem.

Thelytoky in the honey bee

Thelytoky, the asexual production of females, is rare in honey bees. However, it is ubiquitous in workers of the Cape honey bee Apis mellifera capensis. Thelytoky allows some workers to be reincarnated into the queen phenotype, and thereby selects for reproductive competition among workers. Thelytoky also acts as an exaptation for the emergence of reproductive parasites, the most extreme example of which is an entirely clonal ‘cancerous’ lineage of workers (the Clone) that lethally parasitises colonies of another subspecies Apis mellifera scutellata. The Clone is an enigma because thelytoky results in the accumulation of homozygosity at any loci that are free to recombine, yet the Clone retains considerable heterozygosity. The Clone pays a cost for its thelytoky: the selective removal of homozygous offspring at each generation. We propose that workers, queens and Clones have differing abilities to endure the costs and benefits of sex and asexuality, accounting for the heterogeneous distribution of reproductive strategies across the A. mellifera capensis population. We further suggest that multiple factors must fall into place for thelytoky to emerge as an effective reproductive strategy in a honey bee population, and that geographic isolation resulting in genetic drift and founder effects may have enabled thelytoky to emerge in A. mellifera capensis. Finally, we consider the honey bee in the broader context of haplodiploid Hymenoptera, and argue that constraints on the evolution of sex in non-haplodiploid taxa may make sexual reproduction an evolutionary ‘one-way street’.

Phylogeographic history and taxonomy of some afro-alpine grasses assessed based on AFLPs and morphometry: Deschampsia cespitosa, D. angusta and Koeleria capensis

Phylogeographic studies in the high mountains of Africa are hampered by the limited material available, resulting in insufficient knowledge of taxonomic variation within and among closely related species. Here, we address genetic and morphological variation in three grass species, of which one (Deschampsia angusta) has been reported as narrowly endemic and vulnerable whereas Deschampsia cespitosa and Koeleria capensis are widely distributed also outside the afro-alpine region. We used amplified fragment length polymorphisms (AFLPs) to assess genetic structuring and diversity in material collected during recent field expeditions and included additional herbarium material in morphometric analyses. The plants identified as the endemic D. angusta were genetically very similar to those identified as D. cespitosa from the same mountain (Mt Ruwenzori), forming a single coherent genetic group in STRUCTURE analysis. The plants identified as D. angusta seem to represent extremes of continuous gradients of morphological variation within a single, variable species, D. cespitosa. We found that the afro-alpine material of Deschampsia consists of three genetically very distinct groups corresponding to the three mountains investigated, suggesting persistence in isolated afro-alpine refugia during one or more glacial cycles. In contrast, we found no clear genetic structure in K. capensis. This species harbored very little genetic diversity in all six mountain areas examined, and little genetic rarity except in the Ethiopian Simen Mts. This pattern may be explained by recent colonization of the afro-alpine region from a single source population or possibly by extensive recent gene flow combined with bottlenecks. We found, however, some differentiation between different K. capensis populations from Mt Kilimanjaro, corresponding to two described varieties. This study demonstrates the need for further taxonomic exploration of the enigmatic flora of the isolated afro-alpine ‘sky islands’ and highlights that different species may have conspicuously different phylogeographic histories.

Bidirectional introgressive hybridization between Lepus capensis and Lepus yarkandensis

Lepus capensis and Lepus yarkandensis are two well-established hare species with different habitat preferences and obvious morphological distinctions. L. capensis is common and widespread while L. yarkandensis is an endemic species with a restricted distribution in the Tarim Basin of western China. During field sampling, individuals with a distinct phenotype were found in the contact zone between the two species. To understand the origin of these unclassified individuals, we analyzed morphological and genetic data from 700 individuals including L. yarkandensis, L. capensis and the unclassified individuals. Morphological analyses of the unclassified individuals revealed that they lie between L. yarkandensis and L. capensis. Genetic analyses based on species-specific molecular markers (mitochondrial control region and SRY) showed that the unclassified populations have mtDNA and SRY genes from both L. capensis and L. yarkandensis, suggesting that the unclassified populations result from hybridization between the two species. Interestingly, many identical and/or very similar mtDNA haplotypes were shared between L. capensis populations and L. yarkandensis populations close to their contact zones, which further suggests the existence of extensive bidirectional mtDNA introgression. Similarly, we found evidence for SRY introgression, though it existed at a lower level compared to mtDNA introgression.

Maternal Effects of Herbivory in Impatiens capensis

Maternal effects of herbivory for fitness-related traits of offspring, especially those traits that are expressed later in a plant’s life, have rarely been studied. To better understand how herbivory to the maternal plant influences traits of its progeny and whether this depends on the mating system that produced the seed or the growth environment of the seedling, we examined maternal effects of herbivory in Impatiens capensis. Impatiens capensis is well suited to this study because it exhibits a mixed mating system by producing obligately selfing cleistogamous flowers and facultatively outcrossing chasmogamous flowers on a single plant. In a natural I. capensis population, we manipulated maternal herbivory and collected seeds from cleistogamous and chasmogamous flowers and assessed their fitness in the presence or absence of intraspecific competitors in the greenhouse. We found that maternal herbivory had positive effects for many offspring traits but the magnitude of the maternal effect depended on the offspring competitive context. In addition, for offspring biomass and total flower production, the expression of maternal effects varied with seed source (i.e., chasmogamous or cleistogamous flower). Our results demonstrate that maternal herbivory has consequences for the next generation that persist throughout the offspring life cycle, indicating that there may be important demographic consequences of maternal effects.

Distribution of common dolphins (Delphinus spp.) in the western Atlantic Ocean: a critical re-examination

Due to indications that misidentification (largely confusion among dolphins of the genera Delphinus and Stenella) in the past had led to erroneous assumptions of distribution of the two species of common dolphins (Delphinus delphis and D. capensis) in the western Atlantic Ocean, we conducted a critical re-examination of records of the genus Delphinus from this region. We compiled 460 ‘plottable’ records, required support for confirmation of genus and species identifications, and found many records lacking (and some clearly misidentified). When we plotted only the valid records (n = 364), we found evidence of populations in only three areas, and apparent absence throughout much of the tropical/subtropical regions. Off the east coast of the US and Canada, D. delphis is found from the Georgia/South Carolina border (32°N) north to about 47–50°N off Newfoundland. Since the 1960s, they have apparently been absent from Florida waters. There is no evidence that dolphins of the genus occur in the Gulf of Mexico. Reports of common dolphins from most of the Caribbean Basin are also rejected, and the only place in that region where they are confirmed to occur is off central-eastern Venezuela (a coastal D. capensis population). Off eastern South America, common dolphins appear to be restricted to south of 20°S. There is a coastal long-beaked population found in the South Brazil Bight, and one or more short-beaked populations south and offshore of this (ranging south to at least northern Argentina). The results are very different from commonly-accepted patterns of distribution for the genus in the Atlantic. Most areas of distribution coincide with moderate to strong upwelling and common dolphins appear to avoid warm, tropical waters. This study shows that great care must be taken in identification of similar-appearing long-beaked delphinids, and that uncritical acceptance of records at face value can lead to incorrect assumptions about the ranges of the species involved.

Inheritance of Traits Associated with Reproductive Potential in Apis mellifera capensis and Apis mellifera scutellata Workers

When workers of the thelytokous Cape honeybee, Apis mellifera capensis, come into contact with colonies of the neighboring arrhenotokous subspecies Apis mellifera scutellata, they can become lethal social parasites. We examined the inheritance of 3 traits (number of ovarioles, number of basitarsal hairs, and size of spermatheca) that are thought to be associated with reproductive potential in A. m. capensis workers. To do so, we produced hybrid A. m. scutellata/A. m. capensis queens and backcrossed them to either A. m. capensis or A. m. scutellata drones. We then measured the 3 traits in parental, hybrid, and backcross offspring. We show that the 3 traits are phenotypically correlated. We also show that the expression of ovariole number, basitarsal hairs, and size of spermatheca is influenced by the genotype of the individual and the rearing environment but that the influence of the rearing environment is less important to the number of ovarioles. We hypothesize a single recessive allele (l), present at high frequency in natural A. m. capensis populations, which when homozygous causes larvae to elicit more food. This increased feeding as larvae causes resulting adult workers to develop more queen-like morphology and increased reproductive potential. The number of ovarioles, in contrast, appears to be under independent genetic control.

Herbivory and Competition Interact to Affect Reproductive Traits and Mating System Expression in Impatiens capensis

As a step toward understanding how community context shapes mating system evolution, we investigated the combined role of two plant antagonisms, vegetative herbivory and intraspecific competition, for reproduction and mating system expression (relative production of selfing, cleistogamous and facultatively outcrossing, chasmogamous flowers and fruits) of Impatiens capensis. In a survey of I. capensis populations, we found that vegetative herbivory and intraspecific competition were positively correlated. In a greenhouse experiment where leaf damage and plant density were manipulated, multispecies interactions had dramatic effects on reproductive and mating system traits. Despite having additive effects on growth, herbivory and competition had nonadditive effects for mating system expression, chasmogamous fruit production, flower number and size, and cleistogamous flower production. Our results demonstrate that competitive interactions influence the effect of herbivory (and vice versa) on fitness components and mating system, and thus antagonisms may have unforeseen consequences for mating system evolution, population genetic diversity, and persistence.