Effects of patch shape and group size on the effectiveness of defence by juvenile convict cichlids

Kim, Jaewoo; Grant, James W. A.

doi:10.1016/j.anbehav.2006.08.003

Cited by 11 publications

(10 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[18], [43], [44]), we predicted that the competitive advantage of large body-size would decrease as the group-size increases. Hence, the addition of several small-sized individuals was predicted to make resource defence (i.e.…”

Section: Discussionmentioning

confidence: 99%

Modes of Competition: Adding and Removing Brown Trout in the Wild to Understand the Mechanisms of Density-Dependence

et al. 2013

View full text Add to dashboard Cite

While the prevalence of density-dependence is well-established in population ecology, few field studies have investigated its underlying mechanisms and their relative population-level importance. Here, we address these issues, and more specifically, how differences in body-size influence population regulation. For this purpose, two experiments were performed in a small coastal stream on the Swedish west coast, using juvenile brown trout (Salmo trutta) as a study species. We manipulated densities of large and small individuals, and observed effects on survival, migration, condition and individual growth rate in a target group of intermediate-sized individuals. The generality of the response was investigated by reducing population densities below and increasing above the natural levels (removing and adding large and small individuals). Reducing the density (relaxing the intensity of competition) had no influence on the response variables, suggesting that stream productivity was not a limiting factor at natural population density. Addition of large individuals resulted in a negative density-dependent response, while no effect was detected when adding small individuals or when maintaining the natural population structure. We found that the density-dependent response was revealed as reduced growth rate rather than increased mortality and movement, an effect that may arise from exclusion to suboptimal habitats or increased stress levels among inferior individuals. Our findings confirm the notion of interference competition as the primary mode of competition in juvenile salmonids, and also show that the feedback-mechanisms of density-dependence are primarily acting when increasing densities above their natural levels.

show abstract

Section: Discussionmentioning

confidence: 99%

Modes of Competition: Adding and Removing Brown Trout in the Wild to Understand the Mechanisms of Density-Dependence

et al. 2013

View full text Add to dashboard Cite

show abstract

“…We expected (i) mean growth to be greater within high‐density trials due to a decrease in energy expended on aggression (i.e. less interference competition), as per resource defence theory (Kim & Grant ); (ii) within‐trial growth variance to increase with increased resource patch clumping due to changes in effective competitor number (Fausch ; Noël, Grant & Carrigan ) and resource accessibility; and (iii) individual growth to be most similar in low‐density distributed resource trials due to a 1 : 1 competitor to resource patch ratio, as per the IFD (Noël, Grant & Carrigan ). Lastly, we expected (iv) competitive ability, irrespective of density and resource distribution, to be based on functional morphology and its relation to swimming ability (Ward, Webster & Hart ).…”

Section: Introductionmentioning

confidence: 99%

The interaction between the spatial distribution of resource patches and population density: consequences for intraspecific growth and morphology

Jacobson

Grant

Peres‐Neto

2015

Journal of Animal Ecology

View full text Add to dashboard Cite

Summary1. How individuals within a population distribute themselves across resource patches of varying quality has been an important focus of ecological theory. The ideal free distribution predicts equal fitness amongst individuals in a 1 : 1 ratio with resources, whereas resource defence theory predicts different degrees of monopolization (fitness variance) as a function of temporal and spatial resource clumping and population density. 2. One overlooked landscape characteristic is the spatial distribution of resource patches, altering the equitability of resource accessibility and thereby the effective number of competitors. While much work has investigated the influence of morphology on competitive ability for different resource types, less is known regarding the phenotypic characteristics conferring relative ability for a single resource type, particularly when exploitative competition predominates. 3. Here we used young-of-the-year rainbow trout (Oncorhynchus mykiss) to test whether and how the spatial distribution of resource patches and population density interact to influence the level and variance of individual growth, as well as if functional morphology relates to competitive ability. Feeding trials were conducted within stream channels under three spatial distributions of nine resource patches (distributed, semi-clumped and clumped) at two density levels (9 and 27 individuals). 4. Average trial growth was greater in high-density treatments with no effect of resource distribution. Within-trial growth variance had opposite patterns across resource distributions. Here, variance decreased at low-population, but increased at high-population densities as patches became increasingly clumped as the result of changes in the levels of interference vs. exploitative competition. Within-trial growth was related to both pre-and post-trial morphology where competitive individuals were those with traits associated with swimming capacity and efficiency: larger heads/bodies/caudal fins and less angled pectoral fins. 5. The different degrees of within-population growth variance at the same density level found here, as a function of spatial resource distribution, provide an explanation for the inconsistencies in within-site growth variance and population regulation often noted with regard to density dependence in natural landscapes.

show abstract

“…Trophic resource use among competing fishes may vary with environmental factors in - cluding habitat conditions (e.g. stable versus highly variable ecosystem, Davis et al 2012), prey availability (Shimose et al 2010), or density of competitors (Kim & Grant 2007, Kaspersson et al 2010. In Lake Erhai, the 2 studied habitats are characterized by strong differences in depth, submerged macrophytes, food abundances, and density of predators (Guo et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the abundance of Rhino gobius cliffordpopei was highest in the littoral habitat (water depth < 6 m), followed by sub-littoral habitat (water depth ranging from 6 to 12 m) and lowest in profundal habitat (water depth ranging from 12 to 20 m), whereas the abundance of R. giurinus were highest in the profundal habitat, followed by sub-littoral habitat and lowest in littoral habitat (Guo et al 2012). Density of competitors (the 2 goby species) is also an important factor that influences foraging behavior and competitive processes (Kim & Grant 2007, Kaspersson et al 2010. Therefore, further investigations are needed to elucidate the specific effects of those factors on the patterns of competition and food partitioning be tween the 2 invasive species.…”

Section: Discussionmentioning

confidence: 99%

Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use

Liu¹,

Lek²,

Li³

et al. 2014

Aquat. Biol.

View full text Add to dashboard Cite

Food partitioning is one of the primary mechanisms facilitating the stable cooccurrence of competing species, but very few studies have investigated how food resource use of competing and closely related species varies with life-history stages and habitats. In Lake Erhai (China), the trophic niche of 2 congeneric and co-occurring invasive goby species (Rhinogobius cliffordpopei and R. giurinus) was examined to test the existence of an ontogenetic diet shift and to determine potential differences in trophic niche between species within a habitat and between habitats (i.e. littoral and profundal) within species. Results obtained from gut content and stable isotope analyses revealed a strong trophic niche shift during ontogeny, whereby juveniles mainly consumed macrozooplankton while sub-adults and adults increasingly consumed aquatic insects and Tubificidae. The trophic niche of juveniles was similar between species in each of the 2 habitats but significantly different for sub-adults and adults, notably in littoral habitat. Moreover, the trophic niche was similar between habitats for juveniles of each species, whereas it differed significantly between habitats for sub-adults and adults. This study demonstrates the importance of ontogeny and shows that habitat use can significantly affect food resource use and trophic relationships between 2 co-occurring fish species.KEY WORDS: Species co-occurrence · Niche differentiation · Ontogenetic niche shift · Stable isotope analyses · Rhinogobius · Gut content analysis Resale or republication not permitted without written consent of the publisher

show abstract

Effects of patch shape and group size on the effectiveness of defence by juvenile convict cichlids

Cited by 11 publications

References 26 publications

Modes of Competition: Adding and Removing Brown Trout in the Wild to Understand the Mechanisms of Density-Dependence

Modes of Competition: Adding and Removing Brown Trout in the Wild to Understand the Mechanisms of Density-Dependence

The interaction between the spatial distribution of resource patches and population density: consequences for intraspecific growth and morphology

Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use

Contact Info

Product

Resources

About