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1.
Using a geometric morphometric approach, we explored the variation in skull size and skull shape in banded newts (genus Ommatotriton). The genus Ommatotriton is represented by two allopatric, genetically well‐defined species: Ommatotriton ophryticus and O. vittatus. Within each species, two subspecies have been recognised. The samples used in this study cover the geographical and genetic variation within each species. We found statistically significant variation in skull size between species and among populations within species. When corrected for size, there was no significant variation in shape between species. Our results indicate that the variation in skull shape within the genus Ommatotriton is almost entirely due to size‐dependent, allometric shape changes. The exception is the shape of the ventral skull in males. Males of O. ophryticus and O. vittatus significantly diverge in the shape of the ventral cranium. The ventral skull, more precisely the upper jaw and palate, is directly functionally related to feeding. In general, our results indicate that allometry is a significant factor in the morphological variation of banded newts. However, the divergence in the ventral skull shape of males indicates that sexual selection and niche partitioning may have influenced the evolution of skull shape in these newts.  相似文献   

2.
Macroecological analyses often test hypotheses at the global scale, or among more closely related species in a single region (e.g. continent). Here, we test several hypotheses about climatic niche widths among relatively closely related species that occur across multiple continents, and compare patterns within and across continents to see if they differ. We focus on the lizard genus Varanus (monitor lizards), which occurs in diverse environments in Africa, Asia, and Australia. We address three main questions. 1) How do climatic niche breadths of species on a given niche axis change based on the position of species along that niche axis? (E.g. are species that occur in more extreme environments more narrowly specialized for those conditions?) 2) Are there trade‐offs in niche breadths on temperature and precipitation axes among species, or are niche widths on different axes positively related? 3) Is variation in niche breadths among species explained primarily by within‐locality seasonal variation, or by differences in climatic conditions among localities across the species range? We generate a new time‐calibrated phylogeny for Varanus and test these hypotheses within and between continents using climatic data and phylogenetic methods. Our results show that patterns on each continent often parallel each other and global patterns. However, in many other cases, the strength of relationships can change dramatically among closely related species on different continents. Overall, we found that: 1) species in warmer environments have narrower temperature niche breadths, but there is no relationship between precipitation niche breadth and niche position; 2) temperature and precipitation niche breadths tend to be positively related among species, rather than showing trade‐offs; and 3) within‐locality seasonal variation explains most variation in climatic niche breadths. Some of these results are concordant with previous studies (in amphibians and North American lizards), and might represent general macroecological patterns.  相似文献   

3.

Background  

The genus Cuscuta L. (Convolvulaceae), commonly known as dodders, are epiphytic vines that invade the stems of their host with haustorial feeding structures at the points of contact. Although they lack expanded leaves, some species are noticeably chlorophyllous, especially as seedlings and in maturing fruits. Some species are reported as crop pests of worldwide distribution, whereas others are extremely rare and have local distributions and apparent niche specificity. A strong phylogenetic framework for this large genus is essential to understand the interesting ecological, morphological and molecular phenomena that occur within these parasites in an evolutionary context.  相似文献   

4.
This work explores the possibility that constraints on genetic variation guide host shifts and are responsible for the evolutionary conservatism of host affiliation in phytophagous insects. To this end, we used full- and half-sib breeding designs to screen two species of the North American bettle genus Ophraella for genetic variation in larval and adult feeding responses to several host plants of other species of Ophraella. All the plants are in the family Asteraceae. In O. conferta, we observed effectively no feeding response, and hence no genetic variation in response, to three of five test plant species; only those plants related to the species' natural hosts evoked genetically variable responses. In O. artemisiae, adults displayed genetic variation in response to a congener of the natural host, but not to two distantly related plants. However, significant variation among full-sib broods in larval feeding suggests the existence of nonadditive genetic variance in feeding response to all five species of test plants—although survival was very low on most of them. The results suggest that patterns of presence versus apparent absence of detectable genetic variation may be related to the chemical similarity of plants to the insects' natural hosts, but not evidently to the phylogenetic history of host affiliation within the genus. Almost all genetic correlations in responses to host plants were not significantly different from zero; the few significant correlations were positive, and negative correlations that might explain host specificity were not found. Our data do not explain why exclusive shifts to new hosts should occur, but the apparent lack of genetic variation in responses to some plants suggests that the direction of host shifts is genetically constrained.  相似文献   

5.
Food niche variation within a population of white-spotted charr, Salvelinus leucomaenis, was investigated by means of mark and recapture to examine the simplification that conspecific individuals are ecologically equivalent. Food diversity measured on the basis of living form of dietary organisms demonstrated variability in food niche in incidence, degree, and stability. As inferred from body size distribution and fish movement, niche variation was inexplicable by social rank hierarchy or foraging habitat rotation, and occasional niches were deemed to be realized individually. Higher annual growth rate shown by those with a larger niche width indicated the adaptive significance in niche variation. Assuming trade-off between feeding efficiency and predation risk, phenotypic plasticity was suggested to determine the food niche specialization of individuals to maximize lifetime fitness.  相似文献   

6.
Geometric morphometric and phylogenetic analyses, applied to 43 species of Russelliana, shed light on the evolution of insect wing shape. Unconstrained and constrained ordination techniques are introduced to detect patterns of the forewing shape variation within genus. Results show a high congruence between forewing shape variation and host-plant preference supporting monophyly of most phylogenetic groups in Russelliana. Reconstruction of the ancestral forewing state shows its similarity to a forewing shape of Solanaceae feeding species defined as ancestors by the phylogenetic study supporting a hypothesis as to a primary association of Russelliana with Solanaceae. In contrast to some other comparative studies on insect wing shape, results of the present study reveal a strong correlation between variation of forewing shape in Russelliana and its phylogeny. Potential influence of vicariant events and host shifts on the evolution of forewing shape is discussed.  相似文献   

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9.
Most Malagasy primate communities harbor a diverse assemblage of omnivorous species. The mechanisms allowing the coexistence of closely related species are poorly understood, partly because only preliminary data on the feeding ecology of most species are available. We provide an exemplary feeding ecology data set to illuminate coexistence mechanisms between sympatric gray and Madame Berthe’s mouse lemurs (Microcebus murinus, M. berthae). We studied their feeding ecology in Kirindy Forest/CFPF, a highly seasonal dry deciduous forest in western Madagascar. Between August 2002 and December 2007, we regularly (re-)captured, marked, and radiotracked females of both species. A combination of direct behavioral observations and fecal analyses revealed that both Microcebus species used fruit, arthropods, gum, insect secretions, and small vertebrates as food sources. However, Microcebus berthae and M. murinus differed in both composition and seasonal variation of their diets. Whereas the diet of Microcebus murinus varied seasonally and was generally more diverse, M. berthae relied mainly on insect secretions supplemented by animal matter. The differences were also reflected in a very narrow feeding niche of Microcebus berthae and a comparatively broad feeding niche of M. murinus. Resource use patterns of Madame Berthe’s and more so of opportunistic gray mouse lemurs broadly followed resource availability within the strongly seasonal dry forest. Feeding niche overlap between the 2 sympatric species was high, indicating that food resource usage patterns did not reflect niche partitioning, but can instead be explained by constraints due to food availability.  相似文献   

10.
Species showing intraspecific morphological variation tend to be very difficult to identify using morphological characters. One such example is the cicada genus Mogannia where some species show considerable intraspecific variation mainly exhibited by wing pattern and body colouration. Thirty-one variants covering different putative species of Mogannia were recognized and illustrated in the present paper. Molecular data of mitochondrial COI and Cytb sequences were employed to test the level of variation and phylogeny of them. The existence of a ‘barcoding gap’ between intraspecific and interspecific genetic divergences and the reciprocally monophyletic clades indicate that all the closely related variants represent a single species, and that all these variants correspond to six species, respectively. However, the evolutionary relationships of intraspecific variants are not resolved possibly due to insufficient genetic variation among them. Our results indicated that some morphological characters, especially the wing pattern and body colouration, and even the number of apical processes of the aedeagus in a couple of related species, must be used with great caution in delimiting Mogannia species and their relatives. The factors responsible for intraspecific morphological variation and phylogeny of Mogannia spp. are preliminarily discussed.  相似文献   

11.
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The genus Phymaturus (Reptilia: Liolaemidae) is distributed in the mountains and rocky plateaux of Argentina and Chile and comprises two groups of species, palluma and patagonicus. The two lineages have diverged early in the evolution of the genus and up to today, there is very little geographical overlap between them. We worked with records of localities from the literature, herpetological collections and field data to evaluate habitat suitability of the genus Phymaturus. We used 11 environmental variables to develop environmental niche models (ENMs) for each group within the genus using the Maxent software, and to determine those variables that best explain the distribution of each group. We also estimated measures of niche similarity using ENMTools to determine whether niche differentiation is real or apparent. The geographical overlap between the groups was very low considering the large geographical range of the genus. Some variables, such as mean annual temperature, soil type and bare soil cover, have a high contribution to the models for both groups. The current niche overlap between Phymaturus groups indicates that the environmental niches of the palluma and patagonicus groups are not equivalent. Based on background analysis, we cannot reject the hypothesis that similarity (or divergence) between groups of Phymaturus is no more than expected based on the availability of habitat. The results of this study are a first approximation to the knowledge of the environmental variables associated with the palluma and patagonicus groups, and reveal that the ecological differences found between these groups are more likely due to habitat availability in their respective regions than to differences in habitat preferences.  相似文献   

13.
Strutzenberger, P., Brehm, G., Bodner, F. & Fiedler K. (2010). Molecular phylogeny of Eois (Lepidoptera, Geometridae): evolution of wing patterns and host plant use in a species‐rich group of Neotropical moths. —Zoologica Scripta, 39, 603–620. Eois is a pantropical genus of Geometridae moths with currently 250 valid described species, the majority of which occur in the Neotropics. Eois is a prominent component of Andean moth communities locally accounting for up to ~10% of geometrid individuals. We address the evolution of wing patterns and host plant use in Neotropical Eois and provide a preliminary assessment on the monophyly and biogeographic history of the entire genus as well as affinities within the subfamily Larentiinae. We applied Bayesian, maximum likelihood and maximum parsimony methods of phylogenetic reconstruction to a 142 taxon dataset of partial COI (1220 bp) and Ef1α (1066 bp) sequences resulting in the largest taxon set of geometrid moths analyzed in a molecular phylogenetic study so far. Monophyly of Eois was always strongly supported. Ten monophyletic clades were found with good support, seven of which have characteristic wing pattern phenotypes. Only one wing pattern type occurs in two clades. Trophic associations with representatives of the family Piperaceae occur in all 8 (of 9) Neotropical clades for which host information is available. Apart from feeding on Piper, at least two Eois species in Ecuador feed on Peperomia, and one on Manekia (all Piperaceae); two further species live on Hedyosmum (Chloranthaceae). Species feeding on Peperomia, Manekia and Hedyosmum are usually nested in Piper‐associated clades. Single records of associations with Gesneriaceae and Monimiaceae are scattered in otherwise Piperaceae‐associated clades. These patterns suggest multiple parallel host shifts away from Piper as ancestral food plant. Old World Eois were recovered as monophylum and sister to Neotropical Eois. Within the subfamily Larentiinae the genus Eois has previously been placed close to the tribe Eupitheciini, but this was not supported in our phylogenetic analyses.  相似文献   

14.
Age variation of radial plates of perittocrinids and aberrant cups of the hybocrinid genus Hoplocrinus from the Middle Ordovician of the St-Petersburg region are examined. Three patterns for the development of folds on the radial plates of perittocrinids are recognized. The differences between patterns are of species level. It is proposed here that the folded structures of perittocrinids (as well as the pore-structures of other pelmatozoans) were not only used for respiration, but also very likely for feeding. Tetracionocrinus transitor is a young individual of a species of the genus Perittocrinus or a paedomorphic species of this genus. The study of aberrant cups of Hoplocrinus suggests that its ancestor could have had biserial arms. Phylogenetic implications of this interpretation are discussed, and homologies within the phylum Echinodermata, reassessed. The three-armed genus Baerocrinus may be an aberrant form of a species of the genus Hoplocrinus.  相似文献   

15.
In the present study we evaluated the putative cases of sympatric speciation in the genus Herichthys by studying the variation in head shape using principal component analysis, phylomorphospace and reconstructions of the ancestral states of feeding preferences. Herichthys includes both allopatric and sympatric sister species, as well as sympatric unrelated species and thus offers great potential for evolutionary studies of putatively sympatric speciation. Herichthys is the northernmost group of cichlids in America and one of the most ecologically disparate genera within Middle American cichlids. Fifteen anatomical points were recorded on the heads of 293 specimens of the 11 species recognized within the genus. The results show that in spite of having wide variation in consumed diets, most species of Herichthys are close in morphospace. However, morphological variation was great among the two pairs of sympatric sister species in agreement with the suggested sympatric model of speciation.  相似文献   

16.
Aggregations are widespread across the animal kingdom, yet the underlying proximate and ultimate causes are still largely unknown. An ideal system to investigate this simple, social behavior is the pine sawfly genus Neodiprion, which is experimentally tractable and exhibits interspecific variation in larval gregariousness. To assess intraspecific variation in this trait, we characterized aggregative tendency within a single widespread species, the redheaded pine sawfly (N. lecontei). To do so, we developed a quantitative assay in which we measured interindividual distances over a 90‐min video. This assay revealed minimal behavioral differences: (1) between early‐feeding and late‐feeding larval instars, (2) among larvae derived from different latitudes, and (3) between groups composed of kin and those composed of nonkin. Together, these results suggest that, during the larval feeding period, the benefits individuals derive from aggregating outweigh the costs and that this cost‐to‐benefit ratio does not vary dramatically across space (geography) or ontogeny (developmental stage). In contrast to the feeding larvae, our assay revealed a striking reduction in gregariousness following the final larval molt in N. lecontei. We also found some intriguing interspecific variation: While N. lecontei and N. maurus feeding larvae exhibit significant aggregative tendencies, feeding N. compar larvae do not aggregate at all. These results set the stage for future work investigating the proximate and ultimate mechanisms underlying developmental and interspecific variation in larval gregariousness across Neodiprion.  相似文献   

17.
Geographic range size is a key ecological and evolutionary characteristic of a species, yet the causal basis of variation in range size among species remains largely unresolved. One major reason for this is that several ecological and evolutionary traits may jointly shape species' differences in range size. We here present an integrated study of the contribution of ecological (dispersal capacity, body size and latitudinal position) and macroevolutionary (species' age) traits in shaping variation in species' range size in Coenagrion damselflies. We reconstructed the phylogenetic tree of this genus to account for evolutionary history when assessing the contribution of the ecological traits and to evaluate the role of the macroevolutionary trait (species' age). The genus invaded the Nearctic twice independently from the Palearctic, yet this was not associated with the evolution of larger range sizes or dispersal capacity. Body size and species' age did not explain variation in range size. There is higher flight ability (as measured by wing aspect ratio) at higher latitudes. Species with a larger wing aspect ratio had a larger range size, also after correcting for phylogeny, suggesting a role for dispersal capacity in shaping the species' ranges. More northern species had a larger species' range, consistent with Rapoport's rule, possibly related to niche width. Our results underscore the importance of integrating macroecology and macroevolution when explaining range size variation among species.  相似文献   

18.
Plant feeding insects and the plants they feed upon represent an ecological association that is thought to be a key factor for the diversification of many plant feeding insects, through differential adaptation to different plant selective pressures. While a number of studies have investigated diversification of plant feeding insects above the species level, relatively less attention has been given to patterns of diversification within species, particularly those that also require plants for oviposition and subsequent larval development. In the case of plant feeding insects that also require plant tissues for the completion of their reproductive cycle through larval development, the divergent selective pressure not only acts on adults, but on the full life history of the insect. Here we focus attention on Rhinusa antirrhini (Curculionidae), a species of weevil broadly distributed across Europe that both feeds on, and oviposits and develops within, species of the plant genus Linaria (Plantaginaceae). Using a combination of mtDNA (COII) and nuclear DNA (EF1‐α) sequencing and copulation experiments we assess evidence for host associated genetic differentiation within R. antirrhini. We find substantial genetic variation within this species that is best explained by ecological specialisation on different host plant taxa. This genetic differentiation is most pronounced in the mtDNA marker, with patterns of genetic variation at the nuclear marker suggesting incomplete lineage sorting and/or gene flow between different host plant forms of R. antirrhini, whose origin is estimated to date to the mid‐Pliocene (3.77 Mya; 2.91–4.80 Mya).  相似文献   

19.
Phylogenetic analysis of the New World Ptininae (Coleoptera: Bostrichoidea)   总被引:2,自引:0,他引:2  
A phylogenetic analysis of the New World Ptininae (Anobiidae) was conducted with representatives of nine of ten New World genera, several Old World genera and seven more of the ten subfamilies of Anobiidae. One hundred and two characters (forty‐three multistate) from thirty‐four taxa were used. The single cladogram shows Ptininae as monophyletic and the sister group of the remaining Anobiidae, supporting their placement as subfamilies of a monophyletic Bostrichidae. Genus Niptus Boieldieu is polyphyletic supporting recognition of Pseudeurostus Heyden and the creation of a new genus to encompass the remaining New World species of Niptus. Flightlessness has evolved a minimum of three times within Ptininae and myrmecophily has probably evolved three times within just the New World taxa. The classifications of Ptininae and the remaining Anobiidae are examined and the evolution of feeding habits, myrmecophily and wing loss are discussed.  相似文献   

20.
The karyotype analysis ofPeumus boldus reveals a remarkable differentiation of chromosomes in size and form. C-banding pattern and interphase nuclei are discribed and compared with other genera. The great variation in leaf-shape and growth-form is continuous and correlated with the very diverse habitats of the species. The recognition of infraspecific taxa is therefore not recommended. The lower leaf surface is very uniform within the monotypic genus and ± similar with that ofSiparuna. The different evolutionary strategies ofPeumus and related genera are discussed and show a different eco-systematic situation than inMollinedia andSiparuna.
  相似文献   

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