Mecoptera is paraphyletic: multiple genes and phylogeny of Mecoptera and Siphonaptera

Phylogenetic relationships among members of the Mecoptera and Siphonaptera were inferred from DNA sequence data. Four loci (18S and 28S ribosomal DNA, cytochrome oxidase II and elongation factor-1α) were sequenced for 69 taxa selected to represent major flea and mecopteran lineages. Phylogenetic analyses of these data support a paraphyletic Mecoptera with two major lineages: Nannochoristidae + (Siphonaptera + Boreidae) and Meropidae + ((Choristidae + Apteropanorpidae) (Panorpidae + (Panorpidae + Bittacidae))). The flea family Ctenophthalmidae is paraphyletic, and the Ceratophylloidea is monophyletic. Morphological evidence is discussed which is congruent with the placement of Siphonaptera as sister group to Boreidae.     

The head of Merope tuber (Meropeidae) and the phylogeny of Mecoptera (Hexapoda)

External and internal features of the head of adults of Merope tuber were examined and described in detail. The results were compared to conditions found in other members of Mecoptera and other antliophoran lineages. A list of characters of different body parts and life stages is presented. The parsimony analysis and a recent evaluation of thoracic features suggest a basal placement of Merope within monophyletic Pistillifera. The monophyly of Mecoptera was not supported by our data set. Nannochoristidae (Nannomecoptera) was placed as sistertaxon of a clade comprising Diptera and Siphonaptera. Cephalic features supporting this group are modifications of the mouthparts linked to feeding on liquid substrates. Considering recent results of extensive morphological and molecular investigations we consider this placement of Nannochoristidae and the implied mecopteran paraphyly as a possible artefact. Potential cephalic autapomorphies of Mecoptera are the presence of a tooth-like projection of the gena and a prepharyngeal tube, the absence of M. frontolabralis, and the origin of M. tentoriooralis on the middle region of the anterior tentorial arm. Despite of the conspicuous morphological differences between Caurinus and the other boreid genera the family forms a well supported clade. A sistergroup relationship between Boreidae and Pistillifera is confirmed. A unique synapomorphy is the presence of specialized dilator muscles of the salivary duct. The reconstruction of the relationships of the pistilliferan taxa is strongly impeded by a serious lack of morphological data. However, a group comprising Eomeropidae, Choristidae, Apteropanorpidae, Panorpidae and Panorpodidae is supported in our analyses. Further well documented anatomical data are needed for a reliable reconstruction of mecopteran relationships. The collecting and morphological study of larvae should also have high priority. Inherent problems are extreme secondary modifications of cephalic features of Caurinus and Nannochorista.     

Cold hardiness of Apteropanorpa tasmanica Carpenter (Mecoptera: Apteropanorpidae)

There are very few investigations of cold hardiness in native Australian insects, and no such studies on insects from Tasmania. The Apteropanorpidae is a family of wingless Mecoptera endemic to Tasmania, comprising four described species that can be active in winter. In this study, we used infrared video thermography to investigate the physiological and behavioural responses of Apteropanorpa tasmanica to fast (0.3 degrees Cmin(-1)) and slow (0.03 degrees Cmin(-1)) rates of temperature reduction down to -10 degrees C. No adults survived cooling to -10 degrees C at either cooling rate. Mean supercooling points (SCPs) from fast cooling were -7.0 and -4.6 degrees C in 2002 and 2003, respectively. Ice nucleation always began in the abdomen, however, the position of nucleation within the abdomen varied between individuals. There was no relationship between SCP and body length, and no significant difference in SCPs between males and females. Stress-induced fast walking began when insects reached approximately -1.5 degrees C. Cooling rate did not affect the SCP or the temperature at which the behavioural stress response began. Adults survived for only short periods of time in the supercooled state; however they survived in the laboratory for up to 60 days at 4 degrees C, indicating their longevity at more favourable temperatures. Members of the Apteropanorpidae are adapted to the relatively warm, maritime climate currently influencing Tasmania.     

What does feeding system morphology tell us about feeding?

Feeding is the set of behaviors whereby organisms acquire and process the energy required for survival and reproduction. Thus, feeding system morphology is presumably subject to selection to maintain or improve feeding performance. Relationships among feeding system morphology, feeding behavior, and diet not only explain the morphological diversity of extant primates, but can also be used to reconstruct feeding behavior and diet in fossil taxa. Dental morphology has long been known to reflect aspects of feeding behavior and diet but strong relationships of craniomandibular morphology to feeding behavior and diet have yet to be defined.     

The phylogenetic system of the Mecoptera

Abstract. Many families like the Mesochoristidae, Agetopanorpidae and Permopanorpidae, which were believed by earlier writers to be Mecoptera, are members of the stem group of the Antliophora (Diptera Mecoptera+Siphonaptera) or of stem groups of monophyletic groups of even higher rank (e.g. Mecopteroidea). Others - like the so-called 'Pro-tomecoptera' from the Permian of the Kusnetsk Basin - are not even closely related to the Mecopteroidea. Only the families mentioned in the following phylogenetic system of the Mecoptera are definitely members of the order:
1 Nannomecoptera (Nannochoristidae)
2 Pistillifera
2.1 Raptipedia (Neorthophlebiidae, Bittacidae, Cimbrophlebiidae)
2.2 Opisthogonopora
2.2.1 Boreomorpha (Boreidae)
2.2.2 Meropomorpha (Meropeidae)
2.2.3 Panorpomorpha
2.2.3.1 Eomeropina (Eomeropidae=Notiothaumidae)
2.2.3.2 Panorpina
2.2.3.2.1 Apteropanorpini (Apteropanorpidae)
2.2.3.2.2 Panorpini
2.2.3.2.2.1 Choristoidea (Choristidae)
2.2.3.2.2.2 Panorpoidea (Orthophlebiidae, Dinopanorpidae, Austropan-orpidae, Muchoriidae, Panorpodidae, Panorpidae)
The Orthophlebiidae and Neorthophlebiidae are not monophyletic. There are, however, no characters preserved which would allow a clarification of the exact relations between members of these two groups and the families derived from them. The fossil Xenochoristidae, Triasso-choristidae, Mesopanorpodidae and Robinjohniidae may be further members of the Mecoptera. Their exact phylogenetic relations, however, are unknown.     

Mandible Form Relative to the Main Food Type in Ladybirds (Coleoptera: Coccinellidae)

The Coccinellidae is an economically important family within the Coleoptera. Some members are phytophagous pests, but many are beneficial predators and valuable biocontrol agents. This study investigates the morphology of the mandibles of adult Coccinellidae in relation to diet. Using scanning electron microscopy on 86 species of Coccinellidae, it was found that the morphology of the mandibles was dictated by the general feeding method, and could only be used to indicate a phytophagous, mycophagous or carnivorous diet. Phytophagous Coccinellidae of the subfamily Epilachninae had mandibles with denticulate apical teeth and setae for feeding on leaf material. The mandibles of the mycophagous Psylloborini had secondary teeth on the ventral apical tooth for collecting fungal spores. The mandibles of carnivorous Coccinellidae and Scymninae had either a bifid or unidentate apex. The unidentate mandible seemed to be restricted to coccidophagous species. Many species also had a mandibular groove along which prey body juices were conducted. Although mandible morphology could be related to the overall feeding method, there was no relationship between specific diet or food taxon and mandible shape. Mandible shape does not appear to be especially restricting for changes in diet either in the ecological sense or over evolutionary time. Mandible morphology is of limited use in determining diet and host specificity in Coccinellidae that are being selected as potential biocontrol agents.     

Sex and size related differences in the dry season feeding patterns of elephants in Chobe National Park, Botswana

Differences in feeding patterns of the African elephant were examined by sex and age during the dry season in a dystrophic savanna-woodland ecosystem in northern Botswana. Adult males had the least diverse diet in terms of woody plant species, but they consumed more plant parts than family units. The diameter of stems of food plants broken or bitten off was also greater for adult males than for females and subadult males. Adult males spent more time foraging on each woody plant than did females. The number of woody plant species and individuals present were higher at feeding sites of family units than at feeding sites of adult males, indicating that family units positioned themselves at feeding sites with higher species diversity than those of males. We argue that the most likely explanation for these differences is related to the pronounced sexual size dimorphism exhibited by elephants, resulting in sex differences in browsing patterns due to the allometric relationships that govern the tolerance of herbivores for variation in diet quality. From our results this Body Size Hypothesis is accepted rather than the alternative Scramble Competition Hypothesis, which predicts that adult male elephants consume lower quality browse because they are displaced from preferred browse as an outcome of scramble competition with adult females and their offspring. If the feeding patterns of adult male elephants were affected by intersexual scramble competition, we would expect adult males to browse at a higher level in the canopy than the smaller-bodied females and their offspring. No evidence was found for this, although adult females were found to browse at a higher level in the canopy when feeding in close proximity to subadults and juveniles than when feeding alone. Sex differences in elephant browsing patterns are, we propose, of relevance to understanding and managing elephant impacts on African woodlands.     

Multistate characters and diet shifts: evolution of Erotylidae (Coleoptera)

The dominance of angiosperms has played a direct role in the diversification of insects, especially Coleoptera. The shift to angiosperm feeding from other diets is likely to have increased the rate of speciation in Phytophaga. However, Phytophaga is only one of many hyperdiverse lineages of beetles and studies of host-shift proliferation have been somewhat limited to groups that primitively feed on plants. We have studied the diet-diverse beetle family Erotylidae (Cucujoidea) to determine if diet is correlated with high diversification rates and morphological evolution by first reconstructing ancestral diets and then testing for associations between diet and species number and diet and ovipositor type. A Bayesian phylogenetic analysis of morphological data that was previously published in Leschen (2003, Pages 1-108 in Fauna of New Zealand, 47; 53 terminal taxa and 1 outgroup, 120 adult characters and 1 diet character) yielded results that are similar to the parsimony analyses of Leschen (2003). Ancestral state reconstructions based on Bayesian and parsimony inference were largely congruent and both reconstructed microfungal feeding (the diet of the outgroup Biphyllidae) at the root of the Erotylidae tree. Shifts among microfungal, saprophagous, and phytophagous diets were most frequent. The largest numbers of species are contained in lineages that are macrofungal feeders (subfamily Erotylinae) and phytophagous (derived Languriinae), although the Bayesian posterior predictive tests of character state correlation were unable to detect any significant associations. Ovipositor morphology correlated with diet (i.e., acute forms were associated with phytophagy and unspecialized forms were associated with a mixture of diets). Although there is a general trend to increased species number associated with the shift from microfungal feeding to phytophagy (based on character mapping and mainly restricted to shifts in Languriinae), there is a large radiation of taxa feeding on macrofungi. Cycad feeding is scattered in more deeply diverged taxa and may have preceded the evolution of angiosperm feeding in some groups. Preliminary analysis of diet mapped onto higher beetle phylogenies suggests that about half of the major Coleoptera lineages may have had fungus-feeding ancestors. We discuss the roles of stochastic models and prior distributions of the reconstruction of ancestral character states in the context of the current data.     

Characterization of the long-wavelength opsin from Mecoptera and Siphonaptera: does a flea see?

Mecoptera and Siphonaptera represent two insect orders that have largely been overlooked in the study of insect vision. Recent phylogenetic evidence demonstrates that Mecoptera (scorpionflies) is paraphyletic, with the order Siphonaptera (fleas) nesting as sister to the family Boreidae (snow fleas), showing an evolutionary trend towards reduction in gross eye morphology within fleas. We provide the first molecular characterization of long-wavelength opsins from these three lineages (opsin gene from fleas [FL-Opsin], the Boreidae [B-Opsin], and a mecopteran family [M-Opsin]) and assess the effects of loss of visual acuity on the structure and function of the opsin gene. Phylogenetic analysis implies a physiological sensitivity in the red-green spectrum for these opsins. Analysis of intron splice sites reveals a high degree of similarity between FL-Opsin and B-Opsin as well as conserved splice sites across insect blue-green and long-wavelength opsins. Calculated rates of evolution and tests for destabilizing selection indicate that FL-Opsin, B-Opsin, and M-Opsin are evolving at similar rates with no radical selective pressures, implying conservative evolution and functional constraint across all three lineages.     

Potassium chloride deters Lygus hesperus feeding behavior

A series of bioassays were conducted to determine the response of adult western tarnished plant bugs, Lygus hesperus Knight (Heteroptera: Miridae), to artificial diets containing potassium chloride (KCl). We first examined the feeding behavior of L. hesperus by direct observation in a no‐choice diet feeding arena. We observed a total of 22 Lygus feeding events lasting an average of 411 ± 64 s on the control artificial diet and only three feeding events lasting an average of 11 ± 3 s on the KCl‐treated diet. We then conducted several multiple diet choice bioassays to determine the feeding response of L. hesperus when exposed simultaneously to five artificial diet treatments containing different amounts of KCl. For the first bioassay, we used standard clear parafilm diet packets and for the second bioassay we used dark green parafilm diet packets to hold the various diet treatments. Regardless of the diet packet color, L. hesperus overwhelmingly selected the 0% KCl diet treatment over diets containing 3, 6, 9, or 12% KCl. The third and fourth multiple diet choice bioassays were identical to the first bioassay, except that concentrations of the KCl‐treated diets were reduced. Lygus hesperus consistently selected the control diet over all diets containing more than 0.5% KCl. However, when the concentration of KCl in the diet was reduced to ≤0.4%, there were no significant differences in feeding activity exhibited by L. hesperus. Finally, to determine if the addition of KCl to the diet influenced their upwind response, we examined the responses of L. hesperus that were simultaneously exposed to a control artificial diet and a diet containing 12% KCl in a Y‐tube olfactometer bioassay. Of the 95 adults tested, 47 selected the arm containing the normal diet and 48 selected the arm containing KCl‐treated diet, indicating that dietary constituents did not preferentially attract or repel L. hesperus. The results from these studies strongly suggest that KCl negatively affects L. hesperus feeding behavior by functioning as a strong gustatory deterrent when concentrations exceed 0.5%. Visual and volatile cues appeared to have no role in mediating orientation or feeding behavior under these test conditions.     

Insularity affects head morphology,bite force and diet in a Mediterranean lizard

Island environments differ with regard to numerous features from the mainland and may induce large‐scale changes in most aspects of the biology of an organism. In this study, we explore the effect of insularity on the morphology and performance of the feeding apparatus, a system crucial for the survival of organisms. To this end, we examined the head morphology and feeding ecology of island and mainland populations of the Balkan green lizard, Lacerta trilineata. We predicted that head morphology, performance and diet composition would differ between sexes and habitats as a result of varying sexual and natural selection pressures. We employed geometric morphometrics to test for differences in head morphology, measured bite forces and analysed the diet of 154 adult lizards. Morphological analyses revealed significant differences between sexes and also between mainland and island populations. Relative to females, males had larger heads, a stronger bite and consumed harder prey than females. Moreover, island lizards differed in head shape, but not in head size, and, in the case of males, demonstrated a higher bite force. Islanders had a wider food niche breadth and included more plant material in their diet. Our findings suggest that insularity influences feeding ecology and, through selection on bite force, head morphology. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 469–484.     

The effects of foods consumed after adult eclosion on the mate-searching behavior and feeding preferences of the white-spotted longicorn beetle Anoplophora malasiaca (Coleoptera: Cerambycidae)

The effects of changes in host plants on the mate-searching behavior and feeding preferences of the white-spotted longicorn beetle Anoplophora malasiaca (Thomson) (Coleoptera: Cerambycidae) were examined. All individuals were raised on the same artificial diet until they became pupae. Analysis of the mate-searching behavior of the males showed that many more newly emerged males were attracted to the odor of the artificial diet than to an unbaited control. We prepared three groups of beetles and fed each group on different host plants for one week. The host plants used included the following: an artificial diet (containing Morus alba Linné), Citrus unshiu Marc. branches, and Vaccinium spp. branches. The mate-searching behavior of the males changed in relation to the plant supplied for feeding. Simultaneously, the preference among the three host plants was tested. The newly emerged males preferred the artificial diet. After a week of feeding on one of the three plants, however, the adult males selected and consumed significantly more of the plant that they had just experienced than the other plants. These results suggest that the male mate-location cue can be acquired after adult eclosion. In addition, the male beetles are capable of changing their host-plant preference. If they do so, they use different odor cues for mate location. Newly emerged A. malasiaca females showed no preference for their first choice of food among the three host plants presented, whereas the consumption was significantly larger on C. unshiu branches. After one week of feeding on different host plants, females chose their host plant after the adult stage as well as C. unshiu, but consumed mostly C. unshiu. These results suggest that the food preferences of females are different from those of males. The behavior of females may not be affected by chemical signals from their original host-plant species (as pupae) or from the host-plant species acquired when they emerge as adults.     

Digestive morphology and enzyme activity in the Andean toad Bufo spinulosus: hard-wired or flexible physiology?

Gut plasticity is a trait with implications on animal performance. However, and despite their importance as study models in physiology, research on gut flexibility in amphibians is scarce. In the present work, we analyse digestive adjustments of Bufo spinulosus adult individuals to cope with changes in diet quality and quantity at two organizational levels (i.e., digestive morphology and enzymes). We found that changes in gut size are related to the amount of food ingested, but not to diet composition. This is in agreement with "the gut seasonal change" hypothesis and offers a proximal explanation for this change. Digestive enzymatic activity (maltase and aminopeptidase-N) did not change with diet quality or quantity, which agrees with the hypothesis of "hard-wired physiology in adult amphibians". Both hypotheses are in agreement with the general theoretical framework of gut phenotypic flexibility when interpreted in light of amphibian natural history. In addition, our results indicate that the correlation between feeding frequency and the level of gut up-regulation proposed for interspecific comparisons may also be found at the intraspecific level.     

Effects of Feeding a Histidine-excess Diet and Subsequent Starvation on Liver and Muscle Glycogen,and on Serum Glucose

The effects of feeding with a histidine-excess diet and subsequent starvation on liver and muscle glycogen, and on serum glucose were investigated in young and adult rats.

Feeding with a histidine-excess diet resulted in the accumulation of liver glycogen in both young and adult rats. The hepatic glycogen continued to decrease during starvation, and the liver became almost totally depleted of glycogen after starvation for 48 hr. Glycogen in the liver of young rats starved for 24 hr after previous feeding with a histidine-excess diet was significantly higher than that of young rats starved for 24 hr after previous feeding with a basal diet.

Muscle glycogen after feeding and subsequent starvation was not affected by the types of diets fed previously, muscle glycogen during starvation showing a slight decrease in young rats and a slight increase in adult rats.

Feeding with a histidine-excess diet caused a significant decrease of serum glucose in young rats, but not in adult rats. Serum glucose in young rats was markedly reduced by starvation after previous feeding with a basal diet, but not after previous feeding with a histidine-excess diet. In adult rats, there were no changes in serum glucose between rats starved after feeding with either a basal diet or a histidine-excess diet, and serum glucose was decreased slightly by starvation after feeding with the test diets.

The overall results indicate that the maintenance of serum glucose in young rate even during starvation after previous feeding with a histidine-excess diet might be partially concerned with the export of glucose from the accumulated glycogen in the liver due to the diet.     

Functional Morphology and Sexual Dimorphism of Mouthparts of the Short-Faced Scorpionfly Panorpodes kuandianensis (Mecoptera: Panorpodidae)

Mouthparts are closely associated with the feeding behavior and feeding habits of insects. The features of mouthparts frequently provide important traits for evolutionary biologists and systematists. The short-faced scorpionflies (Panorpodidae) are distinctly different from other families of Mecoptera by their extremely short rostrum. However, their feeding habits are largely unknown so far. In this study, the mouthpart morphology of Panorpodes kuandianensis Zhong et al., 2011 was investigated using scanning electron microscopy and histological techniques. The mandibulate mouthparts are situated at the tip of the short rostrum. The clypeus and labrum are short and lack distinct demarcation between them. The epipharynx is furnished with sublateral and median sensilla patches. The blade-shaped mandibles are sclerotized and symmetrical, bearing apical teeth and serrate inner margins. The maxilla and labium retain the structures of the typical pattern of biting insects. The hirsute galea, triangular pyramid-shaped lacinia, and labial palps are described in detail at ultrastructural level for the first time. Abundant sensilla are distributed on the surface of maxillary and labial palps. The sexual dimorphism of mouthparts is found in Panorpodes for the first time, mainly exhibiting on the emargination of the labrum and apical teeth of mandibles. Based on the features of mouthparts, the potential feeding strategy and feeding mechanism are briefly discussed in Panorpodes.     

Genetically based polymorphisms in morphology and life history associated with putative host races of the water lily leaf beetle,Galerucella nymphaeae

A host race is a population that is partially reproductively isolated from other conspecific populations as a direct consequence of adaptation to a specific host. The initial step in host race formation is the establishment of genetically based polymorphisms in, for example, morphology, preference, or performance. In this study we investigated whether polymorphisms observed in Galerucella nymphaeae have a genetic component. Galerucella nymphaeae, the water lily leaf beetle, is a herbivore which feeds and oviposits on the plant hosts Nuphar lutea and Nymphaea alba (both Nymphaeaceae) and Rumex hydrolapathum and Polygonum amphibium (both Polygonaceae). A full reciprocal crossing scheme (16 crosses, each replicated 10 times) and subsequent transplantation of 1,001 egg clutches revealed a genetic basis for differences in body length and mandibular width. The heritability value of these traits, based on midparent-offspring regression, ranged between 0.53 and 0.83 for the different diets. Offspring from Nymphaeaceae parents were on average 12% larger and had on average 18% larger mandibles than offspring from Polygonaceae parents. Furthermore, highly significant correlations were found between feeding preference of the offspring and the feeding preference of their parents. Finally, two fitness components were measured: development time and survival. Development time was influenced by diet, survival both by cross type and diet, the latter of which suggest adaptation of the beetles. This suggestion is strengthened by a highly significant cross x diet interaction effect for development time as well as for survival, which is generally believed to indicate local adaptation. Although no absolute genetic incompatibility among putative host races was observed, survival of the between-host family offspring, on each diet separately, was lower than the survival of the within-host family offspring on that particular host. Survival of offspring of two Nymphaeaceae parents was about two times higher on Nymphaeaceae than on Polygonaceae, whereas survival of offspring of two Polygonaceae parents was 11 times higher on Polygonaceae than on Nymphaeaceae (based on untransformed data). Based on these results, we conclude that genetically determined polymorphisms in morphology and feeding preference exist in G. nymphaeae, resulting in differential performance. Furthermore, in each diet separately, offspring of between-host family crosses were less fit than offspring of within-host family crosses. These results support the hypothesis that within this species two host races can be distinguished.     

Ecomorphological convergence in planktivorous surgeonfishes

Morphological convergence plays a central role in the study of evolution. Often induced by shared ecological specialization, homoplasy hints at underlying selective pressures and adaptive constraints that deterministically shape the diversification of life. Although midwater zooplanktivory has arisen in adult surgeonfishes (family Acanthuridae) at least four independent times, it represents a clearly specialized state, requiring the capacity to swiftly swim in midwater locating and sucking small prey items. Whereas this diet has commonly been associated with specific functional adaptations in fishes, acanthurids present an interesting case study as all nonplanktivorous species feed by grazing on benthic algae and detritus, requiring a vastly different functional morphology that emphasizes biting behaviours. We examined the feeding morphology in 30 acanthurid species and, combined with a pre‐existing phylogenetic tree, compared the fit of evolutionary models across two diet regimes: zooplanktivores and nonzooplanktivorous grazers. Accounting for phylogenetic relationships, the best‐fitting model indicates that zooplanktivorous species are converging on a separate adaptive peak from their grazing relatives. Driving this bimodal landscape, zooplanktivorous acanthurids tend to develop a slender body, reduced facial features, smaller teeth and weakened jaw adductor muscles. However, despite these phenotypic changes, model fitting suggests that lineages have not yet reached the adaptive peak associated with plankton feeding even though some transitions appear to be over 10 million years old. These findings demonstrate that the selective demands of pelagic feeding promote repeated – albeit very gradual – ecomorphological convergence within surgeonfishes, while allowing local divergences between closely related species, contributing to the overall diversity of the clade.     

The ontogeny of feeding behavior and cranial morphology in the leopard shark Triakis semifasciata (Girard 1854): A longitudinal perspective

While much is known about the ecological and functional morphology of feeding in lower vertebrates, studies of elasmobranch feeding over ontogeny are broadly lacking. In this study, the ontogeny of feeding behavior and morphology were investigated in neonatal and young-of-the-year leopard sharks Triakis semifasciata using morphometric measurements of growth and high-speed videography in a longitudinal study. Five food types were used during filming sessions to facilitate differentiation of modulation and variation over ontogeny. Functional aspects of muscle and buccal volume scaling were investigated through dissection. Growth over ontogeny was shown to influence numerous kinematic variables, while intra- and inter-individual variability was the dominant factor affecting feeding behavior. Modulation of feeding behavior based on food size and elusiveness was present for timing variables and predator motion during the strike, but not for food motion or the relative extent of buccal expansion. Allometric growth occurred in all aspects of external cranial morphology measured, resulting in a shallower head profile, anterior displacement of the mouth, and relatively larger jaw musculature over ontogeny. While the degree to which morphology constrains or enhances behavior cannot be directly quantified, variability in behavior greatly exceeds variability in morphology over early ontogeny. Maintenance of a behaviorally and morphologically versatile feeding apparatus throughout ontogeny is proposed to enhance the exploitation of resources and facilitate a diverse diet in T. semifasciata under variable environmental conditions.     

Ecomorphological study of large canids from the lower Pleistocene of southeastern Spain

An ecomorphological analysis of the skeletal remains of large canids, Canis (Xenocyon) falconeri and Canis etruscus (Mammalia, Carnivora, Canidae), preserved in an assemblage of large mammals from the lower Pleistocene site at Venta Micena (Guadix–Baza Basin, Orce, Granada, southeastern Spain) is reported. Mean body mass of adult individuals was estimated to be around 10 kg for C. etruscus and approximately 28 kg for C. falconeri using multiple regression. A comparative study of tooth measurements in modem canids, using principal components and discriminant function analysis, infers quite different ecomorphological adaptations and feeding behavior for both fossil species. The craniodental morphology of C. falconeri is similar to that shown by extant hypercarnivorous canids whose diet include more than 70% of vertebrate meat, whereas C. etruscus shows a cranial morphology similar to those of modem omnivorous species, thus indicating a dietary niche in which vertebrate meat represented less than 70% of its diet, with other feeding resources making up the balance. These results suggest that there was a marked ecological segregation between both sympatric species of large canids. The find of a complete skull of C. falconeri showing bilateral asymmetry and marked dental anomalies could suggest high levels of genetic homozygosis in the population which inhabited this region during early Pleistocene times, possibly as a consequence of isolation and the low number of individuals. This may have subsequently led to the extinction of C. falconeri in the Western fringe of Europe. The survival of this pathological individual to adulthood indicates that this species may have developed cooperative behavior similar to that of modem African wild dogs.