Feeding selectivity of four species of sympatric stickleback in brackish-water habitats in eastern Canada

Although sympatric populations of sticklebacks occur commonly along the north-eastern coast of North America, very few studies have considered the interspecific relationships within such populations. This paper investigates prey selectivity, feeding behaviour and potential prey availability within sympatric populations from five brackish-water sites in New Brunswick. Differences between the diets of species from different sites were related to differences in the range of prey available. Fish collected from sites with abundant aquatic vegetation consumed greater numbers of prey than those from vegetation-poor sites. The proportions of prey types eaten by both adults and juveniles reflected prey species abundance at the different sites; thus shifts in diet over time were found to be related to changes in the abundance of potential prey and not to shifts in prey preference on the part of the fish. The size of prey consumed was related to mouth size; adult and juvenile Gasterosteus wheatlandi , having the smallest mouths, consumed the smallest prey. Differences in prey size detected in the four species studied were due to differences in the types of prey consumed. Laboratory experiments on feeding behaviour showed that adult Apeltes quadracus and Pungitius pungitius were more efficient at capturing benthic prey than were Gasterosteus aculeatus and G. wheatlandi. Competition for food is thought not to occur in these populations, because of the abundance of potential prey and the morphological constraints on feeding behaviour.     

Metazoan parasites of sticklebacks on Sable Island, Northwest Atlantic Ocean: biogeographic considerations

Three species of sticklebacks ( Apeltes quadracus, Gasterosteus aculeatus , and Pungitius pungitius ( n = 236) were collected from five ponds on Sable Island. The nematodes Pseudoterranova decipiens, Contracaecum sp., Paracuaria adunca , and Cosmucephalus obvelatus , and the cestode Diphyllobothrium ditremum parasitized three-spined sticklebacks ( G. aculeatus ) and four-spined sticklebacks ( A. quadracus ) inhabiting four brackish water ponds. All the parasites except P. decipiens infected nine-spined sticklebacks ( P. pungitius ) from a freshwater pond. In addition, the cestode Schistocephalus pungitii , the copepod Thersitina gasterostei , and the monogenean Gyrodactylus canadensis occurred in nine-spined sticklebacks from the freshwater pond. The two cestodes, the copepod, and the sealworm, P. decipiens , were the most common parasites encountered. The remaining helminths were relatively rare. Most of the parasite species were larval forms which use gulls or seals as definitive hosts. These parasites probably colonized Sable Island with their definitive hosts, whereas only two species ( T. gasterostei and G. canadensis ) successfully colonized the island ponds with their fish hosts. The low parasite species richness encountered is attributed to the impoverished nature of the host fauna of Sable island, and the difficulty of colonization as a result of the island's isolation with respect to the mainland.     

Early life histories of three sympatric sticklebacks in a salt-marsh

The effects of abiotic factors (water level, temperature, dissolved oxygen and salinity) and interspecific competition on the survival and growth of early life stages of three sympatric sticklebacks, Gasterosteus aculeatus , G. wheallandi and Pungitius pungitius , were studied in salt-marsh tide pools near Isle Verte, Quebec. Significant year-to-year variation was observed in the percentage of live eggs per nest, egg incubation times, and the growth and condition of juveniles for all three species. These differences were associated with variations in temperature, oxygen and salinity in the pools. Comparisons of egg survival and juvenile growth rates were also made for G. aculeatus living in two contrasting habitats of the salt-marsh, the harsh and variable tide pools, and a less harsh, less variable freshwater site. Egg incubation times were longer, and the percentage of live eggs per nest lower, in the river than in the pools. However, river juveniles had higher growth rates and condition factors than pool juveniles. Results of experiments to study interspecific competition between juvenile G. aculaetus and juvenile G. wheatlandi were inconsistent, and it is suggested that the effects of abiotic factors on the survival and growth of early life stages in sticklebacks are more important than competition at this site.     

Recent visitations by eels to Sable Island, Canada, confirmed by parasites

The presence of immature stages of Proteocephalus macrocephalus in nine-spined stickleback Pungitius pungitius , four-spined stickleback Apeltes quadracus , three-spined stickleback Gasterosteus aculeatus , and mummichog Fundulus heteroclitus from Sable Island ponds was confirmed using scolex morphology. The occurrence of this eel-specific parasite in these accidental hosts provides evidence for recent visits by eels Anguilla rostrata to the isolated island in the North-west Atlantic Ocean off the east coast of Canada.     

Karyotype differentiation between two stickleback species (Gasterosteidae)

The stickleback family (Gasterosteidae) of fish is less than 40 million years old, yet stickleback species have diverged in both diploid chromosome number (2n) and morphology. We used comparative fluorescence in situ hybridization (FISH) on 2 stickleback species, Gasterosteus aculeatus (2n = 42) and Apeltes quadracus (2n = 46), to ascertain the types of chromosome rearrangements that differentiate these species. The A. quadracus karyotype contains more acrocentric and telocentric chromosomes than the G. aculeatus karyotype. By using bacterial artificial chromosome probes from G. aculeatus in our FISH screen, we found that 6 pericentric inversions and 2 chromosome fusions/fissions are responsible for the greater number of acrocentric and telocentric chromosomes in A. quadracus. While most populations of G. aculeatus have an XX/XY sex chromosome system, A. quadracus has a ZZ/ZW sex chromosome system, as previously reported. However, we discovered that a population of A. quadracus from Connecticut lacks heteromorphic sex chromosomes, providing evidence for unexpected sex chromosome diversity in this species.     

Characterization and evolutionary relevance of the sperm nuclear basic proteins from stickleback fish

We have characterized the sperm nuclear basic proteins (SNBPs) of the sticklebacks in the suborder Gasterosteoidei. The complete amino acid sequence of the protamines from Aulorhynchus flavidus, Pungitius pungitius, Gasterosteus aculeatus, (anadromous) and G. wheatlandi, as well as the sequences of the protamines of several species pairs of freshwater G. aculeatus, have been determined. Analysis of the primary structure of these proteins has shown that: a) despite the relatively low amino acid complexity and small molecular mass of these basic proteins, they are very good molecular markers at the generic level. The bootstrap parsimony analysis using their sequences provides a phylogenetic relationship for the old anadromous species of Gasterosteoidei which is identical to that obtained from morphological and behavioral analysis; b) the comparison of the sequences also suggests that protamines from the suborder Gasterosteoidei have most likely evolved from a common gene in the early Acanthopterygii by an extension of the carboxy terminal portion of the molecule; c) protamines are not good markers for recent postglacial freshwater isolates of G. aculeatus. However, in the unique case of Enos Lake (British Columbia), we have been able to detect an additional minor protamine component in the benthic forms of G. aculeatus that is not present in the limnetic forms. Thus, this new protamine must have appeared during the past 12,000 years concomitantly with the speciation of benthics and limnetics in this lake.     

Habitat segregation in a salt marsh among adult sticklebacks (Gasterosteidae)

Synopsis The spatial distribution, seasonal abundance and diel activity of four sticklebacks,Gasterosteus aculeatus, G. wheatlandi, Pungitius pungitius, andApeltes quadracus. coexisting in a St. Lawrence salt marsh were examined to see how these closely related species share their habitat. While all four species breed in the Riviè des Vases, a tidal creek, only three species are found in the adjacent salt marsh pools,A. quadracus being absent. Results are interpreted in terms of avoidance of interspecific competition for space during the relatively short breeding season at this latitude.     

A checklist of parasites recorded on sticklebacks (Actinopterygii: Gasterosteidae) from Poland

Parasites of the three-spined stickleback, Gasterosteus aculeatus (L.), and the nine-spined stickleback, Pungitius pungitius (L.), from brackish and freshwater habitats in Poland are listed. The following list was compiled from published records and own long-term studies. Parasites are listed alphabetically in meaningful groups of parasites with notes about their location on the host and distribution in Poland with references. A total of 51 species (taxa) of parasites were recorded on G. aculeatus (3 Apicomplexa, 1 Microsporidia, 3 Peritrichia, 1 Myxozoa, 7 Digenea, 2 Monogenea, 10 Cestoda, 10 Nematoda, 7 Acanthocephala, 3 Copepoda, 1 Branchiura, 2 Hirudinea, 1 Bivalvia) and 16 parasites on P. pungitius (1 Apicomplexa, 1 Microsporidia, 2 Peritrichia, 4 Digenea, 1 Monogenea, 2 Cestoda, 2 Nematoda, 1 Copepoda, 1 Branchiura, 1 Bivalvia).     

Parasite fauna in sticklebacks (Gasterosteidae) from bodies of water of the Kola region

The results of a parasitological study of the two species of sticklebacks (Pungitius pungitius and Gasterosteus aculeatus) inhabiting the Kola region are presented. The 42 and 14 species of parasite were found in the nine-spined and three-spined stickleback, respectively. The paucity of the parasite fauna in the three-spined stickleback is observed. Distribution of parasites in Kola waterbodies and ecological peculiarities in system "parasite-host" are presented.     

A three-spined stickleback, Gasterosteus aculeatus L. from the North Atlantic

An unusual occurrence of a three-spined stickleback, Gasterosteus aculeatus , is described from Ocean Weather Station India in the North-east Atlantic. Previous records of G. aculeatus caught well offshore are summarised and reasons for these occurrences are suggested. Mention is made of the possibility of sticklebacks breeding in the open ocean.     

Population biology of three-spined sticklebacks, Gasterosteus aculeatus, in Scotland

The age of maturation, longevity and aspects of anti-predator morphology were studied for seven Gasterosteus aculeatus L. populations in Scotland during 1978 and 1979. All seven populations are annual with less than 1% of adults surviving a second year. At the four mainland study sites, breeding adult sticklebacks were larger than at any of the three Hebridean sites. Adult females were larger than adult males at all sites, except Lennox Castle where parasitism may account for the lack of sexual dimorphism. Two of the Hebridean sites, Loch Fada and Loch a Bharpa have spine-deficient G. aculeatus populations which are morphologically unprotected from predation. In the five normally spined populations, some aspects of defensive morphology (index of increase in critical dimension, ventral spine size) are associated with predation risk, while others (lateral plate number) are not. These data are discussed in relation to the current stickleback literature.     

Physiological aspects of oogenesis in two species of sticklebacks, Gasterosteus aculeatus L. and Apeltes quadracus (Mitchill)

During May at Woods Hole, female Gasterosteus aculeatus periodically produce clutches of 112±19 eggs with an average diameter of 1·31±0·05 mm. The fish generally have primordial follicles ranging up to 0·56 mm diameter and a clutch of larger follicles undergoing synchronous growth. The size of oocytes within a growing clutch appears to be random within a population, which indicates that recruitment of clutches is not induced by a local environmental event. The largest oocytes within the population of primordial follicles have just begun vitellogenesis but are temporarily arrested. All oocytes within follicles larger than 1·1 mm diameter undergo spontaneous maturation and enlarge to preovulatory size when incubated at 16° C in a simple saline medium. Added deoxycorticosterone can induce similar events in somewhat smaller follicles placed in culture. Thus, in vivo , follicles grow from 0·56 to 1·1 mm diameter by vitellogenesis, and further enlargement is achieved by hydration during steroid-induced maturation. Females carrying follicles in maturational stages also have a new clutch of follicles entering vitellogenic growth from the population of primordial follicles. Injection of human chlorionic gonado-tropin causes a recruitment of follicles into vitellogenesis regardless of the stage of follicles within the growing clutch. One interpretation of these results is that when vitellogenic follicles reach a diameter of 1·1 mm a surge of gonadotropin(s) induces the follicle cells to release steroid, which results in oocyte maturation; the same surge also recruits a new clutch of vitellogenic oocytes. Qualitatively similar results were obtained for Apeltes quadracus ; thus the recruitment phenomenon observed for G. aculeatus may be a general feature among sticklebacks.     

Production of the three-spined stickleback, Gasterosteus aculeatus L., in the River Weaver, England

1. The production of three-spined sticklebacks, Gasterosteus aculeatus , estimated in the margin of a large channelized lowland river, averaged 42.3 g m⁻² yr⁻¹ and the P/B ratio was 3.7. The production value greatly exceeds those previously recorded for G. aculeatus and results from the very high population densities.
2. Life-bistory tactics of the sticklebacks included both r- and K-selected traits.
3. The fish were carnivorous in the summer months but predominantly detritivorous in the winter.     

The distribution of glochidia of the Swan mussel, Anodonta cygnea (Mollusca) on the Three-spined stickleback Gasterosteus aculeatus (Pisces)

The pattern of infestation by glochidia of the Swan mussel, Anodonta cygnea , on a population of the Three-spined stickleback, Gasterosteus aculeatus was studied over a period of 12 months. The results obtained are considered under the four headings of incidence, intensity, the effect of fish size and the toDoeraDhical distribution of oarasites on the host.     

Effect of body weight and temperature on the maximum daily food consumption of Gasterosteus aculeatus L. and Phoxinus phoxinus (L.): selecting an appropriate model

The relationships between the maximum, daily food consumption, body weight and water temperature for the stickleback, Gasterosteus aculeatus L. , and the minnow, Phoxinus phoxinus (L.), were studied. The two species occupy the same lakes in mid-Wales, but differ in that G. aculeatus has a true stomach whereas P. phoxinus lacks a true stomach.
For both species, the relationship between food consumption (F) and body weight ( W ) could be described by the model: log_eF=a + b log_e W . The effect of temperature (T) could be incorporated in the form: log_ef= a + b, log_e W+b₂log_e T. These models were selected because they accounted for a high proportion of the variance in the dependent variable, and because an analysis of the residuals obtained after fitting a model showed no trends which would have signalled the inadequacy of the model.     

A receiver bias in the origin of three-spined stickleback mate choice

Receiver-bias models of signal evolution predict that male sexually selected traits evolve through prior selection for other functions. Female three-spined sticklebacks (Gasterosteus aculeatus) in many populations show a mating preference for males with a red throat and jaw. It has been proposed that this preference evolved because the choice of males with red coloration confers direct and indirect benefits to females in accordance with the Fisher-Zahavi model of sexual selection. We present indirect evidence that the preference is an effect of a receiver bias in the perceptual or cognitive system of G. aculeatus for the colour red, which may have arisen in the context of foraging. In laboratory trials, male and female three-spined and nine-spined sticklebacks (Pungitius pungitius) responded most strongly to red objects outside a mating context. This result demonstrates a correlation between a sexually selected trait and an intrinsic attraction to red objects, and supports the sensory-exploitation model for the evolution of red nuptial coloration in three-spined sticklebacks.     

A temperature-dependent growth model for the three-spined stickleback Gasterosteus aculeatus

Specific growth rates of individually reared juvenile three-spined sticklebacks Gasterosteus aculeatus were investigated under laboratory conditions to parameterize a complete temperature-dependent growth model for this species. To test the applicability of experimentally derived optima in growth response rates to natural conditions, the effects of commercial pellets and natural prey on growth rates were investigated. In addition, to test for seasonal effects on growth, laboratory trials were performed in both spring and winter. Growth took place from 5 to 29° C with a temperature for optimum growth reaching a sharp peak at 21° C. Modelled optimal temperature for maximum growth was estimated to be 21.7° C and lower and upper temperatures for growth were estimated to be 3.6 and 30.7° C, respectively. There were no significant differences in growth rates between fish reared on invertebrates or commercial pellets. Seasonal effects on growth were pronounced, with reduced growth rates in the winter despite similar laboratory conditions. On average, 60% higher growth rates were achieved at the optimum temperature in summer compared to the winter. The strong seasonality in the growth patterns of G. aculeatus indicated here reduces the applicability of the model derived in this study to spring and summer conditions.     

Calcium and salinity as selective factors in plate morph evolution of the three-spined stickleback (Gasterosteus aculeatus)

Identifying the causal factors underlying natural selection remains a key challenge in evolutionary biology. Although the genetic basis for the plate morph evolution of three-spined stickleback (Gasterosteus aculeatus) is well described, the environmental variables that form the basis for different morphs are not understood. We measured the effects of dissolved calcium and salinity on the growth of sticklebacks with different plate morphs from Scotland and Poland. There was a significant interaction of calcium with plate morph for fish from both regions, with complete morph sticklebacks growing more slowly at low calcium concentrations and low morph sticklebacks showing divergent responses to calcium concentration. A Scottish anadromous population showed evidence of local adaptation to high salinity, which was independent of plate morph. Polish and Scottish populations diverged in their response to salinity, suggesting a difference in osmotic regulation. The results implicate a role for calcium in selecting for plate morph evolution in sticklebacks, possibly as a limiting element in skeletal growth.     

Mate choice, sexual imprinting, and speciation: a test of a one-allele isolating mechanism in sympatric sticklebacks

One-allele isolating mechanisms should make the evolution of reproductive isolation between potentially hybridizing taxa easier than two-allele mechanisms, but the generality of one-allele mechanisms in nature has yet to be established. A potentially important one-allele mechanism is sexual imprinting, where the mate preferences of individuals are based on the phenotype of their parents. Here I test the possibility that sexual imprinting promotes reproductive isolation using sympatric species of threespine sticklebacks (Gasterosteus aculeatus). Sympatric species of sticklebacks consist of large benthic species and small limnetic species that are reproductively isolated and adapted to feeding in different environments. I fostered families of F1 hybrids between the species to males of both species. Preferences of these fostered females for males of either type revealed little or no effect of sexual imprinting on assortative mating. However, F1 females showed preferences for males that were similar to themselves in length, suggesting that size-assortative mating may be more important than sexual imprinting for promoting reproductive isolation between species pairs of threespine sticklebacks.     

Infectivity of two nematode parasites, Camallanus lacustris and Anguillicola crassus, in a paratenic host, the three-spined stickleback Gasterosteus aculeatus

Three-spined sticklebacks Gasterosteus aculeatus are frequent paratenic hosts of the nematode parasites Anguillicola crassus and Camallanus lacustris. As paratenic hosts, sticklebacks could spread infection by carrying high numbers of infective stages. In contrast, low infective ability of either parasite for the paratenic host could hinder the spread of infection. In the present study, G. aculeatus was, for the first time, infected under controlled laboratory conditions with defined doses of the parasites. Sticklebacks were exposed to 6, 12, 18 and 24 parasite larvae to determine the infective ability of the 2 nematode species. There were significantly higher infection rates for C. lacustris (18 to 49%) than for A. crassus (4 to 14%) at each exposure dose. In C. lacustris-infected sticklebacks, infection rates tended to be highest after exposure to 12 C. lacustris larvae and lowest after exposure to 24 parasites. In A. crassus-infected sticklebacks, no effect of parasite exposure dose on infection rates was observed. Immunity parameters such as respiratory burst activity and lymphocyte proliferation of head kidney leukocytes recorded 18 wk post exposure were not significantly affected by either parasite or exposure dose. Granulocyte:lymphocyte ratios were elevated only within the stickleback group showing the highest infection intensity of C. lacustris, i.e. to those exposed 18 parasites.