Geometric Morphometric Analysis of Body-Form Variability in Cichlasoma minckleyi, the Cuatro Cienegas cichlid

In this study, I investigate body-form variability in the trophically polymorphic Cuatro Cienegas cichlid, Cichlasoma minckleyi. I use geometric morphometrics to assess and compare size, shape, and allometric patterns within and between dental morphs (distinguished by differences in pharyngeal bones and papilliform or molariform dentitions). I find that dental morphs do not differ significantly in size, shape, or allometric slopes, but do differ in allometric intercepts; thus, dental morphs exhibit different patterns of body-form variability. Within each morph, body-form varies between more fusiform 'piscivores' and deeper-bodied dietary generalists. However, papilliform individuals show a continuous distribution of body-forms, whereas molariform individuals exhibit a discontinuity. I compare results from geometric analyses with those from a traditional (distance-based) morphometric analysis, finding that geometric techniques more clearly recognize discontinuities in shape. Finally, I suggest explanations for observed differences in body-form variability between dental morphs, concluding that the best explanation hinges on the relative importance of genetic and environmental factors in influencing body-form.     

The evolution of cooperative breeding in the African cichlid fish,Neolamprologus pulcher

The conundrum of why subordinate individuals assist dominants at the expense of their own direct reproduction has received much theoretical and empirical attention over the last 50 years. During this time, birds and mammals have taken centre stage as model vertebrate systems for exploring why helpers help. However, fish have great potential for enhancing our understanding of the generality and adaptiveness of helping behaviour because of the ease with which they can be experimentally manipulated under controlled laboratory and field conditions. In particular, the freshwater African cichlid, Neolamprologus pulcher, has emerged as a promising model species for investigating the evolution of cooperative breeding, with 64 papers published on this species over the past 27 years. Here we clarify current knowledge pertaining to the costs and benefits of helping in N. pulcher by critically assessing the existing empirical evidence. We then provide a comprehensive examination of the evidence pertaining to four key hypotheses for why helpers might help: (1) kin selection; (2) pay‐to‐stay; (3) signals of prestige; and (4) group augmentation. For each hypothesis, we outline the underlying theory, address the appropriateness of N. pulcher as a model species and describe the key predictions and associated empirical tests. For N. pulcher, we demonstrate that the kin selection and group augmentation hypotheses have received partial support. One of the key predictions of the pay‐to‐stay hypothesis has failed to receive any support despite numerous laboratory and field studies; thus as it stands, the evidence for this hypothesis is weak. There have been no empirical investigations addressing the key predictions of the signals of prestige hypothesis. By outlining the key predictions of the various hypotheses, and highlighting how many of these remain to be tested explicitly, our review can be regarded as a roadmap in which potential paths for future empirical research into the evolution of cooperative breeding are proposed. Overall, we clarify what is currently known about cooperative breeding in N. pulcher, address discrepancies among studies, caution against incorrect inferences that have been drawn over the years and suggest promising avenues for future research in fishes and other taxonomic groups.     

Different responses of three predatory mite species toTetranychus urticae,Eriophyes dioscoridis andBrevipalpus pulcher: Evidence for the existence of kairomones and allomones

The responses of 3 phytoseiid mite speciesPhytoseiulus persimilis Athias-Henriot,Phytoseius finitimus Ribaga andAmblyseius gossipi Elbadry to allelochemics emitted by prey mite speciesTetranychus urticae Koch,Brevipalpus pulcher (Canestrini & Fanzago) andEriophyes dioscoridis Soliman & Abou-Awad were studied using a test of two-choice assays. The repellent effect elicited by the tenuipalpid mite,B. pulcher and the eriophyid mite,E. dioscoridis againstP. persimilis could be an evidence for the existence of allomones produced by these 2 prey species. The negative response ofP. persimilis to the different stadia ofB. pulcher and the attraction ofP. finitimus toward the same prey suggest that the volatile semiochemicals produced by this prey act as kairomones forP. finitimus and as allomones forP. persimilis. The strong attraction ofP. finitimus andA. gossipi to the different stadia ofT. urticae and the considerable attraction of either predator toB. pulcher compared to the neutral response toE. dioscoridis reveal that both predators show a hierarchy of preference for the kairomones of the 3 prey species studied.      

The food and feeding habits of Eutropius niloticus (Ruppell), family Schilbeidae (Osteichthyes: Siluriformes) in Lake Kainji,Nigeria

Studies on the food and feeding habits of Eutropius niloticus in Lake Kainji, Nigeria revealed that the fish is omnivorous but fed more on insects than on any other food. The most important insects were Povilla adusta Navas nymphs and imagos and adults of the common grasshoppers. Fish, particularly the clupeids Sierrathrissa leonensis Thys Van den Audernaerde and Pellonula afzeliusi Johnels, also formed an important part of the diet. There was seasonal variation of organisms selected for food and there were variations in the dietary items selected by different age groups. Accumulation of fat was found to correlate with seasonal feeding intensity. E. niloticus serves as food for other fishes.     

Variability of kokanee and rainbow trout food habits,distribution, and population dynamics,in an ultraoligotrophic lake with no manipulative management

Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey.     

The reproductive biology of four African catfishes (Osteichthyes: Clariidae) in Anambra River basin,Nigeria

The reproductive biology of Clarias ebriensis, C. agboyiensis, C. macromystax and C. buthupogon was investigated over a period of 32 months in Anambra River basin, Nigeria. Immature (stage I) C. ebriensis and C. agboyiensis were recruited into the fishery in October, and in September in C. macromystax and C. buthupogon. The occurrence of mature (stage III) fish all the year round indicated the potential of the Clarias species to breed at any time of the year. C. ebriensis bred from April–September while breeding occurred from May–September in the other species. The clariids matured between their first and second year of life. C. ebriensis females matured earlier than males but the reserve was the case in C. agboyiensis, C. macromystax and C. buthupogon. Ovary weight was a better indicator of egg number than either total length or body weight in all species. Communal spawning is reported for the first time in Clarias species and its significance to survival discussed.     

Exploitation of the Fecal Shield of the Lily Leaf Beetle, Lilioceris lilii (Coleoptera: Chrysomelidae), by the Specialist Parasitoid Lemophagus pulcher (Hymenoptera: Ichneumonidae)

We investigated signal sources used by the parasitoid Lemophagus pulcher in locating and accepting larvae of its host, the lily leaf beetle, Lilioceris lilii. Olfactometer bioassays revealed that larvae with fecal shields, larvae without shields, the shield alone, and lily leaves damaged by L. lilii were all attractive to female parasitoids. In contact bioassays, L. pulcher females were attracted to shields and showed ovipositor probing independently of whether the larva underneath was L. lilii or a nonhost, suggesting that the shield plays a primary role in short-range host location and host acceptance by L. pulcher. The attractiveness of the shield is at least partly of a chemical nature, since shield extracts applied to dummies increased contact duration and induced ovipositor probing by L. pulcher. Another putative defense system of L. lilii, i.e., oral discharge which is emitted by disturbed larvae, was also attractive to experienced, but not to naive, female parasitoids. In all other tests, naive and experienced female L. pulcher responded to the same signal sources tested, suggesting that the host-selection behavior of this biological control candidate is governed largely by innate responses to host-associated cues.     

The distribution ofFusarium species in soils planted to millet and sorghum in Lesotho,Nigeria and Zimbabwe

Samples from soils planted to millet and sorghum from Lesotho, Nigeria, and Zimbabwe were processed and a total of 3,291Fusarium cultures were recovered. Of these 1,296 cultures were isolated from plant debris and 1,995 cultures were recovered from soil dilutions. The most prevalent species recovered wereF. oxysporum (37%),F. equiset (30%),F. solani (14%),F. moniliforme (6%),F. compactum (5%),F. nygamai (4%), andF. chlamydosporum (2%). OtherFusarium species isolated wereF. merismoides, F. polyphialidicum, F. graminearum, F. subglutinans, F. sambucinum, F. longipes, F. semitectum, F. dimerum, F. lateritium, and a group of cultures designated as population A which resembleF. camptoceras. Fusarium equiseti was the predominant species in soil samples from Nigeria and Zimbabwe, whileF. oxysporum was the predominant species recovered from soil from Lesotho.Contribution No. 1881, Fusarium Research Center, Department of Plant Pathology, The Pennsylvania State University.     

Abundance,distribution, and territory areas of rock-dwelling Lake Tanganyika cichlid fish species

Lake Tanganyika, the second-oldest and second-deepest lake in the world, harbors an impressive cichlid fish fauna counting about 250 endemic species that are characterized by a great level of ecological, morphological, and behavioral specialization. This study describes and compares cichlid fish communities at two rocky shores with differential human impact in the south of Lake Tanganyika. Species inventories and depth-dependent abundances were elaborated. About 41 and 46 sympatric cichlid species were recorded in the two study sites, respectively. Variabilichromis moorii was the most abundant species (29–60% of total number of fishes), followed by Aulonocranus dewindti (3–19%), Tropheus moorii (12%), Ophthalmotilapia ventralis (4–10%), Eretmodus cyanostictus (6–11%), and Cyathopharynx furcifer (0.01–9%). All other species had abundances below 5%. It further emerged that large cichlids such as Petrochromis species, Cyathopharynx furcifer, and Lobochilotes labiatus were very rare at one location, with frequencies of 0.55% or less. Territorial sizes of three particularly abundant species, Variabilichromis moorii, Aulonocranus dewindti, and Tropheus moorii, were assessed by behavioral observations. We distinguished between territorial core areas and total defended area, yielding average core areas between 0.4 (V. moorii) and 1.6 m² (T. moorii), and total defended areas averaging for each species between 1.6 (V. moorii) and 5.0 m² (A. dewindti) with no significant differences between the two study sites. The data on individual densities are also relevant for evolutionary studies, in that they allow more accurate calculations of effective population sizes.     

Use of mires and food habits of sika deer in the Oze Area,central Japan

Sika deer Cervus nippon entered the Oze Area, a snowy area in central Japan, in the 1990s. The use of mires and the food habits of this species were studied in 1999 and 2000. Deer used the mires immediately after snow melted and did not use the mires in mid summer, although they did use them lightly in autumn. The summer food habits differed from those of the deer population living in Nikko in the lower area: non-Sasa graminoids and other monocotyledonous leaves occupied more (approximately 30%) of the feces in the former population, whereas Sasa nipponica, a dwarf bamboo, was the dominant food (60%) of the latter population. Seasonal changes in fecal composition in the Oze deer were that mire graminoids occupied a considerable portion of their food in spring (11.6%) and summer (17.0%), whereas the amount of dwarf bamboo increased in fall (26.0%). Despite the small size of the mires, Oze deer appear to prefer mires to forests. Nitrogen concentrations of the mire plants did not differ from those of the forest plants; however, foraging efficiency would be greater in the mires and this may explain the preference observed. Despite the small total biomass, leaf biomass of the mire was equivalent to that of the adjacent forest floor. In addition, biomass was concentrated near the ground, or the biomass concentration was greater than that of the forest floor.     

Food habits of Coexisting Salmonines above and below Stronach Dam in the Pine River, Michigan

Although dam removal has become an increasingly popular tool for river restoration, there is limited knowledge regarding the ecological effects of dam removal. The purpose of our study was to document feeding habits of coexisting brook charr, brown trout, and rainbow trout above and below a dam that is in the process of a staged removal. Modification of sediment transport caused by Stronach Dam since 1912 has affected stream channel configuration, fish habitat, and many other physical and biological processes. In order to document salmonine feeding habits above and below the dam, we selected zones to represent downstream conditions and areas of river upstream of the dam that encompassed the original reservoir and a stretch of river further upstream that was not hydraulically influenced by the dam. Because physical habitat largely governs aquatic community composition in streams, we expected these effects to be reflected in the fish and macroinvertebrate communities. In particular, we expected limited prey availability and salmonine feeding in the impacted upstream and downstream zones characterized by fine substrate composition and greater macroinvertebrate diversity and salmonine feeding opportunities in the non-impacted zone characterized by coarse substrate. We also expected mean percent wet stomach content weights to be higher downstream, as other studies have documented an increase in piscivory on blocked migratory prey species downstream of dams. Contrary to expectations, the downstream zone of the river contained the highest abundance of drifting invertebrate taxa and, although differences in habitat occurred among the zones, the diversity of drifting macroinvertebrates and stomach contents of salmonines were similar throughout the river. Thus, in this case, the presence of altered habitat caused by a dam did not appear to negatively affect salmonine food habits. Consequently, we expect no major changes in salmonine food habits after the dam removal is completed.     

Validation of 2D‐animated pictures as an investigative tool in the behavioural sciences: A case study with a West African cichlid fish,Pelvicachromis pulcher

Virtual stimuli represent an increasingly popular tool in the study of animal behaviour. Modern techniques have the potential to simplify and improve traditional experiments using live stimuli. However, the increasing availability of diverse techniques is associated with problems and limitations. Although many new methods have been developed, their validation remains largely untested. In the present study, we therefore performed two experiments to test whether 2‐D animations of predators and conspecifics elicit biologically appropriate behavioural responses in male rainbow kribs, Pelvicachromis pulcher. Individual responses towards a sympatric natural fish predator, Parachanna obscura, were tested using live predators and still colour photographs, animated using PowerPoint©. Compared to control trials (empty aquarium and white computer screen, respectively), individuals decreased their activity in response to both live and animated predators. We found no difference in activity between live and animation trials. Further, we tested individual aggression (frequency of aggressive behaviours) exhibited towards live and animated conspecifics. Individual aggressive behaviours shown towards live and animated conspecifics were positively correlated. Moreover, an individual's mean distance towards the opponent was a suitable proxy for individual aggression permitting the facilitation and standardisation of an individual's aggression through the use of a tracking software compared with the more laborious, traditional manual assessment. Our results show that simple, inexpensive animation techniques have the potential to provide an easy‐to‐apply and useful technological advance in animal behaviour research.     

The influence of sawmill wood wastes on the distribution and population of macroinvertebrates at Benin River, Niger Delta area, Nigeria

The impact of sawmill wood wastes on the distribution of benthic macroinvertebrates at the Sapele section of Benin River, Niger Delta, Nigeria, was investigated from March 2005 to August 2005. A total of 434 individuals were collected by kick-sampling method, representing 21 taxa of benthic macroinvertebrates. Three stations, 1, 2, and 3, were selected from upstream of the site, receiving wood wastes discharge, the impacted site and its down stream, respectively. Among the water quality variables, conductivity, dissolved oxygen, biochemical oxigen demand (BOD(5)), nitrate-nitrogen, phosphate-phosphorus, transparency, and alkalinity were significantly different (P<0.05) among the stations. Orthogonal comparison by Duncan's multiple range test showed that station 2 (the impacted site) was the cause of the difference. More sensitive species such as Ephemeroptera or Plecoptera were completely absent from station 2, the impacted site. Species abundance was similar in station 1 and 3, indicating that the wood wastes must have adversely affected the distribution of these macroinvertebrates, especially the intolerant species. The wood waste discharge not only altered the water chemistry, but also stimulated the abundance of less-sensitive macroinvertebrate species.     

The longitudinal distribution of macroinvertebrates and fish in a lower Niger delta river (River Sombreiro) in Nigeria

Summary The longitudinal distribution of macroinvertebrates and fish in a lower Niger delta river (R. Sombreiro) was studied from November 1979 to June 1982.When combined with an earlier study on the physico-chemical features of the river (NWADIARO, 1984), two zones could be discerned. These are (a) an upstream, soft, acid freshwater reach, approximately 86 km long, inhabited mainly by insects, with the dwarf cichlid fishPelvicachromis/Chromidotilapia complex as the distinctive fish type and (b) a downstream, hard, neutral to slightly alkaline brackish water zone, about 30 km long, populated mainly by Crustacea (shrimps and crabs) and molluscs, withMonodactylus sebae as the characteristic fish.The diversity of macroinvertebrates and fish in the upstream zone was togher than in the downstream zone.     

Behavioral response to familiar and unfamiliar neighbors in a territorial cichlid, <Emphasis Type="Italic">Neolamprologus pulcher</Emphasis>

Some territorial species have been shown to react more aggressively toward unfamiliar conspecifics than established neighbors, a behavior referred to as the dear enemy phenomenon. Laboratory experiments were conducted to determine whether males of a territorial African cichlid, Neolamprologus pulcher, can discriminate between size-matched familiar and unfamiliar male neighbors and whether they respond more aggressively toward unfamiliar males. It was found that males spent significantly more time near the territorial boundary that they shared with unfamiliar neighbors and directed significantly more aggressive behavior toward these individuals.     

Ontogenetic changes in diel activity,food habits and spatial distribution of juvenile and adult creek chub,Semotilus atromaculatus

Synopsis Juvenile creek chub, Semotilus atromaculatus, differed ecologically from adults. They were essentially diurnal, fed on small prey (adult diptera and aquatic adult coleoptera) and were found mainly in shallow littoral water (0.8 m depth) of a Québec oligotrophic lake. In contrast, adults were principally nocturnal, fed on larger prey (Gammaridae, diptera larvae, diptera pupae and ephemeroptera larvae) and were found in deeper water (1.2, 2.0 and 2.9 m depth). The overlap in diet between juvenile and adult fish was 10 percent. We found that predation by brook charr, Salvelinus fontinalis, upon creek chub was low, as only 5 chart stomachs of the 302 examined contained a total of 16 juvenile chub and none contained adult chub. Laboratory observations revealed that under low light intensity (0.17 lux) adult creek chub fed as efficiently as under high light intensity (22 lux). Several possible hypotheses to explain the evolution of the two different strategies exhibed by adult and juvenile creek chub are discussed.     

Female-to-male shift of mouthbrooding in a cichlid fish,Tanganicodus irsacae,with notes on breeding habits of two related species in Lake Tanganyika

Synopsis Parental-care patterns and mating systems of three goby-like cichlids in Lake Tanganyika were investigated. In Tanganicodus irsacae females mouthbrooded eggs and small young for about two weeks and then males took over the role for about one week. Field observations of tagged fish suggest that this species is monogamous: a male's home range largely overlapped with that of its mate, while their home ranges were segregated from those of similar-sized consexual adults. Eretmodus cyanostictus also performed female-to-male shift of mouthbrooding and appeared to be monogamous. The third species, Spathodus marlieri, however, exhibited exclusively maternal mouthbrooding. The differences in parental care and mating system among the three species are discussed in relation to their feeding habits, and the pattern of monogamy in the goby-like cichlids is compared with those of other fishes.     

Lipoprotein crystals in the yolk platelet of a teleost,Pelvicachromis pulcher (Cichlidae)

Summary Yolk-platelet crystals in the oocytes of the teleost Pelvicachromis pulcher (Cichlidae) were shown, using electron diffraction and tilting of thinsectioned specimens, to possess an orthorhombic lattice with unit-cell sides a=8.3 nm, b=16.6 nm and c=18.0 nm. They thus closely resemble the crystals known for a newt (Triturus sp.) and a frog (Xenopus laevis).Supported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg. The author wishes to thank Dr. R. Riehl, Heidelberg, for taxonomic advice