Parasite escape through trophic specialization in a species flock

AbstractIn adaptive radiations species diversify rapidly to occupy an array of ecological niches. In these different niches, species might be exposed to parasites through different routes and at different levels. If this is the case, adaptive radiations should be accompanied by a turnover in parasite communities. How the adaptive radiation of host species might be entangled with such a turnover of parasite communities is poorly documented in nature. In the present study, we examined the intestinal parasite faunas of eleven species belonging to the tribe Tropheini, one of several adaptive radiations of cichlid fishes in Lake Tanganyika. The most parsimonious ancestral foraging strategy among Tropheini is relatively unselective substrate ingestion by browsing of aufwuchs. Certain lineages however evolved more specialized foraging strategies, such as selective combing of microscopic diatoms or picking of macro-invertebrates. We found that representatives of such specialized lineages bear reduced infection with intestinal acanthocephalan helminths. Possibly, the evolution of selective foraging strategies entailed reduced ingestion of intermediate invertebrate hosts of these food-web transmitted parasites. In Tropheini, trophic specialization is therefore intertwined with divergence in parasite infection. We conclude that the study of parasite communities could improve our understanding of host evolution, ecological speciation and the origin of adaptive radiations.

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Trophic specialisation reflected by radular tooth material properties in an “ancient” Lake Tanganyikan gastropod species flock

BMC Ecology and Evolution ◽

10.1186/s12862-021-01754-4 ◽

2021 ◽

Vol 21 (1) ◽

Cited By ~ 1

Author(s):

Wencke Krings ◽

Marco T. Neiber ◽

Alexander Kovalev ◽

Stanislav N. Gorb ◽

Matthias Glaubrecht

Keyword(s):

Mechanical Properties ◽

Lake Tanganyika ◽

Ecological Niches ◽

Species Flock ◽

Trophic Specialization ◽

East African ◽

Tooth Morphology ◽

Lake Formation ◽

Feeding Substrate ◽

Radular Tooth

Abstract Background Lake Tanganyika belongs to the East African Great Lakes and is well known for harbouring a high proportion of endemic and morphologically distinct genera, in cichlids but also in paludomid gastropods. With about 50 species these snails form a flock of high interest because of its diversity, the question of its origin and the evolutionary processes that might have resulted in its elevated amount of taxa. While earlier debates centred on these paludomids to be a result of an intralacustrine adaptive radiation, there are strong indications for the existence of several lineages before the lake formation. To evaluate hypotheses on the evolution and radiation the detection of actual adaptations is however crucial. Since the Tanganyikan gastropods show distinct radular tooth morphologies hypotheses about potential trophic specializations are at hand. Results Here, based on a phylogenetic tree of the paludomid species from Lake Tanganyika and adjacent river systems, the mechanical properties of their teeth were evaluated by nanoindentation, a method measuring the hardness and elasticity of a structure, and related with the gastropods’ specific feeding substrate (soft, solid, mixed). Results identify mechanical adaptations in the tooth cusps to the substrate and, with reference to the tooth morphology, assign distinct functions (scratching or gathering) to tooth types. Analysing pure tooth morphology does not consistently reflect ecological specializations, but the mechanical properties allow the determination of eco-morphotypes. Conclusion In almost every lineage we discovered adaptations to different substrates, leading to the hypothesis that one main engine of the flock’s evolution is trophic specialization, establishing distinct ecological niches and allowing the coexistence of taxa.

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Be different to be better: the effect of personality on optimal foraging with incomplete knowledge

Theoretical Ecology ◽

10.1007/s12080-021-00517-7 ◽

2021 ◽

Author(s):

Poppy M. Jeffries ◽

Samantha C. Patrick ◽

Jonathan R. Potts

Keyword(s):

Optimal Foraging ◽

Optimal Foraging Theory ◽

Foraging Strategy ◽

Foraging Strategies ◽

Partial Knowledge ◽

Marginal Value ◽

Animal Populations ◽

Plausible Mechanism ◽

Insight Into ◽

Modelling Approach

AbstractMany animal populations include a diversity of personalities, and these personalities are often linked to foraging strategy. However, it is not always clear why populations should evolve to have this diversity. Indeed, optimal foraging theory typically seeks out a single optimal strategy for individuals in a population. So why do we, in fact, see a variety of strategies existing in a single population? Here, we aim to provide insight into this conundrum by modelling the particular case of foraging seabirds, that forage on patchy prey. These seabirds have only partial knowledge of their environment: they do not know exactly where the next patch will emerge, but they may have some understanding of which locations are more likely to lead to patch emergence than others. Many existing optimal foraging studies assume either complete knowledge (e.g. Marginal Value Theorem) or no knowledge (e.g. Lévy Flight Hypothesis), but here we construct a new modelling approach which incorporates partial knowledge. In our model, different foraging strategies are favoured by different birds along the bold-shy personality continuum, so we can assess the optimality of a personality type. We show that it is optimal to be shy (resp. bold) when living in a population of bold (resp. shy) birds. This observation gives a plausible mechanism behind the emergence of diverse personalities. We also show that environmental degradation is likely to favour shyer birds and cause a decrease in diversity of personality over time.

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More than Meets the Eye: Functionally Salient Changes in Internal Bone Architecture Accompany Divergence in Cichlid Feeding Mode

International Journal of Evolutionary Biology ◽

10.1155/2012/538146 ◽

2012 ◽

Vol 2012 ◽

pp. 1-9 ◽

Cited By ~ 3

Author(s):

R. Craig Albertson ◽

W. James Cooper ◽

Kenneth A. Mann

Keyword(s):

Genetic Basis ◽

Dominant Mode ◽

Bone Architecture ◽

Foraging Strategies ◽

Craniofacial Skeleton ◽

Suction Feeding ◽

Foraging Mode ◽

Feeding Mode ◽

Adaptive Radiations ◽

African Cichlids

African cichlids have undergone extensive and repeated adaptive radiations in foraging habitat. While the external morphology of the cichlid craniofacial skeleton has been studied extensively, biomechanically relevant changes to internal bone architecture have been largely overlooked. Here we explore two fundamental questions: (1) Do changes in the internal architecture of bone accompany shifts in foraging mode? (2) What is the genetic basis for this trait? We focus on the maxilla, which is an integral part of the feeding apparatus and an element that should be subjected to significant bending forces during biting. Analyses of μCT scans revealed clear differences between the maxilla of two species that employ alternative foraging strategies (i.e., biting versus suction feeding). Hybrids between the two species exhibit maxillary geometries that closely resemble those of the suction feeding species, consistent with a dominant mode of inheritance. This was supported by the results of a genetic mapping experiment, where suction feeding alleles were dominant to biting alleles at two loci that affect bone architecture. Overall, these data suggest that the internal structure of the cichlid maxilla has a tractable genetic basis and that discrete shifts in this trait have accompanied the evolution of alternate feeding modes.

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Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

Conservation Physiology ◽

10.1093/conphys/coaa111 ◽

2020 ◽

Vol 8 (1) ◽

Author(s):

Monique Ladds ◽

David Rosen ◽

Carling Gerlinsky ◽

David Slip ◽

Robert Harcourt

Keyword(s):

Foraging Strategy ◽

Central Place ◽

Dive Duration ◽

Foraging Strategies ◽

Body Morphology ◽

Sea Lions ◽

Fur Seals ◽

Adequate Food ◽

Physiological Capacity ◽

Total Body Oxygen

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

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Behavioral and trophic segregations help the Tahiti petrel to cope with the abundance of wedge-tailed shearwater when foraging in oligotrophic tropical waters

Scientific Reports ◽

10.1038/s41598-020-72206-0 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Andreas Ravache ◽

Karen Bourgeois ◽

Henri Weimerskirch ◽

Angélique Pagenaud ◽

Sophie de Grissac ◽

...

Keyword(s):

Trophic Ecology ◽

Isotope Analysis ◽

Foraging Strategy ◽

Gps Tracking ◽

Ecological Niches ◽

Extensive Search ◽

Tropical Area ◽

Time Space ◽

Dna Metabarcoding ◽

Breeding Seasons

Abstract Two species breeding in sympatry are more likely to coexist if their ecological niches are segregated either in time, space or in trophic habits. Here, we combined GPS-tracking, stable isotope analysis and DNA metabarcoding analysis to understand how the rare Tahiti petrel Pseudobulweria rostrata (TP) copes with the very abundant (i.e. 500,000 breeding pairs) wedge-tailed shearwater Ardenna pacifica (WTS) when breeding in sympatry in a tropical area. WTS foraged in restricted areas along their path, while TP predominantly foraged using extensive search behavior, suggesting a more opportunistic foraging strategy. Interspecific overlap of foraging areas was higher than intraspecific overlap. Breeding seasons largely overlap between species during the study, but TP seems to be asynchronous breeders. TP fed upon prey with higher δ15N values than WTS, and their diet was mainly composed of deep-sea organisms. TP could feed upon dead prey floating at the surface while WTS preyed mainly upon fish species that generally move in schools. Our study highlights several segregating mechanisms (temporal, behavioral and trophic) that could facilitate the coexistence of the two species despite the predominant number of WTS, and provides the very first information on the foraging and trophic ecology of the poorly-known TP.

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Optimal Lévy-flight foraging in a finite landscape

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.1158 ◽

2015 ◽

Vol 12 (104) ◽

pp. 20141158 ◽

Cited By ~ 24

Author(s):

Kun Zhao ◽

Raja Jurdak ◽

Jiajun Liu ◽

David Westcott ◽

Branislav Kusy ◽

...

Keyword(s):

Power Law ◽

Animal Movement ◽

Foraging Strategy ◽

Foraging Strategies ◽

Foraging Efficiency ◽

Lévy Flight ◽

Step Size ◽

Levy Flight ◽

Ballistic Motion ◽

Wide Range

We present a simple model to study Lévy-flight foraging with a power-law step-size distribution in a finite landscape with countable targets. We find that different optimal foraging strategies characterized by a wide range of power-law exponent μ opt , from ballistic motion ( μ opt → 1) to Lévy flight (1 < μ opt < 3) to Brownian motion ( μ opt ≥ 3), may arise in adaptation to the interplay between the termination of foraging, which is regulated by the number of foraging steps, and the environmental context of the landscape, namely the landscape size and number of targets. We further demonstrate that stochastic returning can be another significant factor that affects the foraging efficiency and optimality of foraging strategy. Our study provides a new perspective on Lévy-flight foraging, opens new avenues for investigating the interaction between foraging dynamics and the environment and offers a realistic framework for analysing animal movement patterns from empirical data.

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Long- versus short-range foraging strategies of hoary (Lasiurus cinereus) and silver-haired (Lasionycteris noctivagans) bats and the consequences for prey selection

Canadian Journal of Zoology ◽

10.1139/z85-371 ◽

1985 ◽

Vol 63 (11) ◽

pp. 2507-2515 ◽

Cited By ~ 87

Author(s):

Robert M. R. Barclay

Keyword(s):

Short Range ◽

Prey Availability ◽

Prey Selection ◽

Foraging Strategy ◽

Foraging Strategies ◽

Lasiurus Cinereus ◽

Echolocation Calls ◽

Straight Line ◽

Lasionycteris Noctivagans ◽

Selection Of

Habitat use, temporal activity, foraging behaviour, and prey selection of hoary bats (Lasiurus cinereus) and silver-haired bats (Lasionycteris noctivagans) were studied at Delta Marsh, Manitoba. Bat activity was assessed by monitoring echolocation calls with ultrasonic detectors. Prey availability was determined using sticky and Malaise traps and dietary information was obtained from fecal analysis. Both species were active all night and foraged primarily in the lee of a narrow forested ridge. Lasionycteris noctivagans foraged in a manner that indicates that it detects and pursues prey over short distances. These bats fly slowly, are highly manoeuverable, and were commonly observed feeding on swarms of insects in small clearings. They use echolocation calls that support the notion of a short-range foraging strategy and feed opportunistically on whatever insects are available. Lasiurus cinereus, on the other hand, uses a long-range prey detection and pursuit foraging strategy. They fly rapidly along straight line paths in open areas and use echolocation calls designed to detect insects at a distance. The diet consists primarily of large insects (moths, beetles, and dragonflies), but the bats nonetheless feed opportunistically. The foraging strategy likely restricts the availability and profitability of small insects as prey.

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Intertidal foraging by gentoo penguins in a macroalgal raft

Antarctic Science ◽

10.1017/s095410201900052x ◽

2020 ◽

Vol 32 (1) ◽

pp. 43-44

Author(s):

James B. McClintock ◽

Charles D. Amsler ◽

Margaret O. Amsler ◽

William R. Fraser

Keyword(s):

Environmental Change ◽

Foraging Behaviour ◽

Foraging Strategy ◽

Foraging Strategies ◽

Marion Island ◽

Pygoscelis Papua ◽

General Consensus ◽

Foraging Tactics ◽

Pygoscelid Penguins ◽

Foraging Tactic

Foraging strategies in gentoo penguins (Pygoscelis papua) have been well studied (e.g. Croxall et al. 1988, Robinson & Hindell 1996, Lescroël et al. 2004, Takahashi et al. 2008, Xavier et al. 2017). The general consensus is this largest member of the three pygoscelid penguins displays both nearshore benthic and pelagic foraging tactics to consume combinations of crustaceans and fish. In a recent study, Carpenter-Kling et al. (2017) reported that gentoos at sub-Antarctic Marion Island displayed a novel foraging strategy that consisted of alternating typical lengthy foraging trips with much shorter nearshore afternoon trips. They suggest the latter foraging behaviour may be a response to suboptimal feeding conditions caused by local environmental change. This novel discovery reinforces the fact that, despite considerable study, not all foraging tactics in penguins have been documented. In this paper, we describe what we believe to be, yet another undocumented foraging tactic employed by gentoos.

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Changes in foraging behaviour during the infective stage of entomopathogenic nematodes

Parasitology ◽

10.1017/s0031182000065306 ◽

1995 ◽

Vol 110 (5) ◽

pp. 583-590 ◽

Cited By ~ 25

Author(s):

E. E. Lewis ◽

S. Selvan ◽

J. F. Campbell ◽

R. Gaugler

Keyword(s):

Metabolic Rate ◽

Entomopathogenic Nematodes ◽

Storage Period ◽

Foraging Strategy ◽

Heterorhabditis Bacteriophora ◽

Steinernema Carpocapsae ◽

Foraging Strategies ◽

Infective Juvenile ◽

Infective Stage ◽

Energy Reserves

SUMMARYStudies of foraging strategies are often complicated by competing goals of the forager. In contrast, non-feeding infective juvenile entomopathogenic nematodes forage exclusively for a single host. Two questions were posed: (1) what is the relationship between metabolic rate, energy reserves and foraging strategy and (2) when a foraging strategy fails, will an infective-stage parasite switch strategies? Three species of entomopathogenic nematodes were stored in water and changes in their behaviour, metabolic rate, energy reserves, and infectivity were measured throughout the storage period. Steinernema carpocapsae ambushes insect hosts, whereas S. glaseri and Heterorhabditis bacteriophora cruise forage. Steinernema carpocapsae was least active and had the lowest metabolic rate. Heterorhabditis bacteriophora was more active and had the highest metabolic rate. Steinernema glaseri was most active and had an intermediate metabolic rate. Neither cruising species changed foraging strategy. Steinernema carpocapsae decreased nictation (a behaviour associated with ambushing only) and increased their locomotory rate. Any change in searching strategy occurred without assessment of the profitability or distribution of potential hosts, but the advantage this confers is unknown.

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Individual-learning ability predicts social-foraging strategy in house sparrows

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2010.1151 ◽

2010 ◽

Vol 278 (1705) ◽

pp. 582-589 ◽

Cited By ~ 43

Author(s):

Edith Katsnelson ◽

Uzi Motro ◽

Marcus W. Feldman ◽

Arnon Lotem

Keyword(s):

Personal Information ◽

Passer Domesticus ◽

Learning Task ◽

Foraging Strategy ◽

Individual Learning ◽

Social Foraging ◽

Learning Ability ◽

Foraging Strategies ◽

Learning Abilities ◽

The Individual

Social foragers can use either a ‘producer’ strategy, which involves searching for food, or a ‘scrounger’ strategy, which involves joining others' food discoveries. While producers rely on personal information and past experience, we may ask whether the tendency to forage as a producer is related to being a better learner. To answer this question, we hand-raised house sparrow ( Passer domesticus ) nestlings that upon independence were given an individual-learning task that required them to associate colour signal and food presence. Following the testing phase, all fledglings were released into a shared aviary, and their social-foraging tendencies were measured. We found a significant positive correlation between individual's performance in the individual-learning task and subsequent tendency to use searching (producing) behaviour. Individual-learning score was negatively correlated with initial fear of the test apparatus and with body weight. However, the correlation between individual learning and searching remained significant after controlling for these variables. Since it was measured before the birds entered a social group, individual-learning ability could not be the outcome of being a producer. However, the two traits may be initially associated, or individual learning could facilitate producing behaviour. To our knowledge, this is the first evidence that associates individual-learning abilities with social-foraging strategies in animal groups.

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