Ecology and evolution of sympatric sticklebacks (Gasterosteus): specialization for alternative trophic niches in the Enos Lake species pair

1984 ◽  
Vol 62 (11) ◽  
pp. 2280-2286 ◽  
Author(s):  
P. Bentzen ◽  
J. D. McPhail
Keyword(s):  
Body Size ◽  
Standard Length ◽  
Feeding Behaviour ◽  
Prey Size ◽  
Distinct Species ◽  
Fixed Time ◽  
Threespine Stickleback ◽  
Sexually Dimorphic ◽  
Species Pair ◽  
Trophic Niches

Two morphologically distinct species of threespine stickleback (Gasterosteus) coexist in Enos Lake on Vancouver Island. For convenience these species are referred to as "limnetics" and "benthics." We used three experiments to compare the feeding performance of the two species and to test the hypothesis that limnetics are adapted for planktivory whereas benthics are adapted to forage on substrates. The results support this conclusion. When tested for maximum prey size; benthics consumed larger prey (relative to their body size) than limnetics. Benthics also were more successful than limnetics in foraging on a substrate. When allowed to forage for a fixed time on a detritus substrate, benthics of both sexes captured more prey than male limnetics, even though male limnetics directed as many feeding strikes at the substrate as did the benthics. Female limnetics would not forage on a detritus substrate. Limnetics were more successful in feeding on plankton than benthics. When held in mesh enclosures suspended in Enos Lake, limnetics consumed more plankton than benthics. Small limnetics (26–36 mm standard length) consumed nearly four times more plankton than large limnetics (44–50 mm standard length). The small limnetics were all either mature females or immature males; the large limnetics were all mature males. The results of the benthic foraging and plankton feeding comparisons support the additional conclusion that Enos Lake limnetics are sexually dimorphic in their feeding behaviour.

The evolution of sexual dimorphism in the skink Eumeces laticeps: an example of sexual selection

1985 ◽  
Vol 63 (5) ◽  
pp. 995-1002 ◽  
Author(s):  
Laurie J. Vitt ◽  
William E. Cooper Jr.
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Breeding Season ◽  
Prey Size ◽  
Maximum Size ◽  
Head Size ◽  
Sexually Dimorphic ◽  
Eumeces Laticeps ◽  
Aggressive Male ◽  
The Mean

Adults of the skink Eumeces laticeps are sexually dimorphic in coloration, body size, head size, and relative head size. Males have larger heads at a given body size than females and the divergence in relative head size is coincident with the size at which sexual maturity is reached. Although there were no differences between sexes in tail loss frequencies, there were substantial differences in frequencies of body and head scars, a consequence of aggressive male–male interactions. Prey size was correlated with body and head size and males tended to eat larger prey items than females. However, both sexes are capable of eating prey much larger than the mean or maximum size of prey found in stomachs, suggesting that resource partitioning is a consequence of sexual size differences rather than a cause. The heads of males at a given body size increase during the breeding season, and a combination of head and body size apparently determines the outcome of intrasexual aggressive encounters. Moreover, small males were never observed with females during the breeding season, and those males observed "guarding" females were significantly larger than males observed in the absence of females. We conclude that sexual selection accounts for many of the differences in morphological traits between sexes of E. laticeps.

Predator communities associated with brook stickleback (Culaea inconstans) prey: patterns in body size

2006 ◽  
Vol 63 (2) ◽  
pp. 297-309 ◽  
Author(s):  
Mara S Zimmerman
Keyword(s):  
Body Size ◽  
Standard Length ◽  
Prey Size ◽  
Community Type ◽  
Upper Peninsula ◽  
Field Surveys ◽  
Culaea Inconstans ◽  
Size Relationship ◽  
Brook Stickleback ◽  
Large Predators

Prey body size is often inversely correlated with largest size of coexisting predators, yet few studies have examined this relationship in the context of entire predator communities. Using field surveys and laboratory trials, this study tested whether a size relationship exists between brook stickleback (Culaea inconstans) prey and the largest coexisting predator in the context of nested predator communities at 26 sites across Michigan's upper peninsula. Small predators, limited to consuming small sticklebacks, were widely distributed and equally common in pond, breached pond, and stream habitats. Large predators consumed all stickleback sizes, occurred at fewer sites, and were found more frequently in stream than in pond and breached pond habitats in one of the two survey years. Predator communities were categorized as small-predator and mixed-predator communities. Small-predator communities included small, gape-limited predators only. Sticklebacks apparently reached a size refugia from predation (>42 mm standard length) in this community type. Mixed-predator communities included both small and large predators and had no size refugia for sticklebacks. Although predator distributions were nested in this system, prey size was correlated with the largest predator size at each site. Stickleback length was negatively correlated with maximum predator length and was smaller in mixed-predator than in small-predator communities.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

scholarly journals Diet composition and feeding habits of the eyespot skate, Atlantoraja cyclophora (Elasmobranchii: Arhynchobatidae), off Uruguay and northern Argentina

2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora
Keyword(s):  
Body Size ◽  
Diet Composition ◽  
Prey Size ◽  
Prey Availability ◽  
Feeding Habits ◽  
Warm Season ◽  
Cold Season ◽  
The North ◽  
Multiple Hypothesis ◽  
Modelling Approach

ABSTRACT The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º - 38ºS) and crabs in the north region (38º - 41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora , but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.

scholarly journals Size-related Change in the Visual Resolution of Sunfish (Lepomis spp.)

1994 ◽  
Vol 51 (9) ◽  
pp. 2017-2026 ◽  
Author(s):  
William E. Walton ◽  
Stephen S. Easter Jr. ◽  
Celeste Malinoski ◽  
Nelson G. Hairston Jr.
Keyword(s):  
Body Size ◽  
Standard Length ◽  
Resolving Power ◽  
Pelagic Zone ◽  
Volume Increase ◽  
Fish Size ◽  
Visual Resolution ◽  
Search Volume ◽  
The Mean

Visual resolution of juvenile sunfish (Lepomis spp.) (8–33 mm standard length (SL)), although extremely poor in comparison with the larger individuals (38–160 mm SL) used in previous studies, improves rapidly as they grow. Histologically and behaviorally determined (mean reaction angle) visual angles of fish between 10 and 33 mm SL decrease by approximately 50 and 100 minutes of arc, respectively, and decline non-linearly with increasing fish size. Behaviorally determined visual resolution of juvenile sunfish based on maximum location distance (MLD) is equivalent to that calculated from intercone spacing. The mean reaction angle used in previous studies may have underestimated behavioral visual resolution of larger (> 38 mm SL) sunfish by approximately 30%. Visual volume and search volume increase by nearly three orders of magnitude in sunfish between 8 and 50 mm SL. After sunfish exceed 50 mm SL (when they can safely return to the pelagic zone), visual resolution increases comparatively slowly as body size increases. Our results suggest that the size-related change in behavioral visual resolution in sunfish is influenced by other factors in addition to the growth-related changes in the resolving power of the retina.

scholarly journals Scaling the feeding mechanism of the largemouth bass (Micropterus salmoides): motor pattern

1995 ◽  
Vol 198 (5) ◽  
pp. 1161-1171 ◽  
Author(s):  
P Wainwright ◽  
B Richard
Keyword(s):  
Body Size ◽  
Largemouth Bass ◽  
Standard Length ◽  
Prey Capture ◽  
Micropterus Salmoides ◽  
Motor Pattern ◽  
Onset Time ◽  
Small Fish ◽  
Scaling Effects ◽  
Emg Signal

We present the first analysis of scaling effects on the motor pattern of a feeding vertebrate. Data are presented for the effects of body size on the pattern of activity in four head muscles during prey capture in the largemouth bass, Micropterus salmoides. Electromyographic (EMG) recordings were made from three expansive-phase muscles (the epaxialis, the sternohyoideus and the levator arcus palatini) and one compressive-phase muscle (the adductor mandibulae), during the capture of small fish prey. Recordings were made of 181 prey-capture events from 19 bass that ranged in size from 83 to 289 mm standard length. We measured seven variables from the myogram of each capture to quantify the temporal pattern of muscle activation, including the duration of activity in each muscle and the onset time of each muscle, relative to the onset of the sternohyoideus muscle. Regressions of the mean value of each variable for the 19 individuals on standard length revealed that only the onset time of the adductor mandibulae changed with fish body size. The increase in onset time of the adductor muscle appears to reflect the longer time taken to open the mouth fully in larger fish. Other research shows that the kinematics of the strike in this species slows significantly with increasing body size. The combined results indicate that the duration of the EMG signal is not directly correlated with the duration of force production in muscles when compared between fish of different sizes. The lack of scaling of burst duration variables suggests that the reduced speeds of prey-capture motion are explained not by changes in the envelope of muscle activity, but rather by the effects of scale on muscle contractile kinetics. These scaling effects may include changes in the relative resistance of the jaw and head structures to movement through water and changes in the intrinsic contractile properties of the muscles of the feeding apparatus.

New Oligaphorura species (Collembola: Onychiuridae) from the forests of East Asia

Zootaxa ◽  
2019 ◽  
Vol 4661 (2) ◽  
pp. 256-270
Author(s):  
XIN SUN ◽  
YU. B. SHVEENKOVA ◽  
ZHIJING XIE ◽  
A. B. BABENKO
Keyword(s):  
New Species ◽  
Body Size ◽  
East Asia ◽  
Russian Far East ◽  
Far East ◽  
Distinct Species ◽  
Species Group ◽  
The Other ◽  
Altai Mountains ◽  
Three New Species

Three new species of the genus Oligaphorura are described from southwestern China (O. wanglangensis sp. nov.) and Russian Far East (O. ussurica sp. nov. and O. kedroviensis sp. nov.). The first species is most similar to O. inya (Weiner & Kaprus’, 2014) known from the Altai Mountains, and can be distinguished from the latter by larger body size and the number of ventral psx (00/000/121101m in O. wanglangensis sp. nov. vs 1/000/212101m in O. inya). The other two species, together with O. montana Weiner, 1994, O. pseudomontana Sun & Wu, 2012 and O. chankaensis Sun & Wu, 2012, form a distinct species-group characterized by the presence of 4+4 pso on antennal base and full-sized anal spines. Both these new species differ from the known congeners of this group by having only 2+2 posterior pso on the head. O. ussurica sp. nov. and O. kedroviensis sp. nov. can be separated due to different number of abdominal pso, i.e. 5(6)5554 in the former vs 44454 in the latter species.

Body size, diet and reproductive ecology of Coluber hippocrepis in the Rif (Northern Morocco)

2004 ◽  
Vol 25 (3) ◽  
pp. 287-302 ◽  
Author(s):  
Juan Pleguezuelos ◽  
Soumia Fahd
Keyword(s):  
Body Size ◽  
Sexual Maturity ◽  
Prey Size ◽  
Reproductive Ecology ◽  
Size Difference ◽  
Southern Europe ◽  
Strait Of Gibraltar ◽  
Dietary Shift ◽  
Intersexual Difference ◽  
Whip Snake

AbstractAlthough it is generally assumed that the Horseshoe Whip Snake (Coluber hippocrepis) originated in northern Africa, its biology and ecology has been studied mainly in southern Europe. In this paper we report on morphology, feeding, and reproductive ecology of Coluber hippocrepis in the Rif region (northern Morocco). Males attained larger sizes than did females, but there was no body-size difference between populations separated by the Strait of Gibraltar. The species feeds exclusively on vertebrates: mammals (45%), reptiles (28%), birds (17%), and amphibians (10%). There was an ontogenetic dietary shift in terms of frequency of prey consumed and in terms of prey size; moreover, an intersexual difference in prey frequency was found. Sexual maturity was attained at 540 mm snout-vent length (SVL) in males, and 720 mm SVL in females. Males showed a vernal spermatogenic cycle. Oviposition occurred at the beginning of summer, and offspring were observed in the field during September.

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