AKODON MOLLIS PDF

Background: The extent of phenotypic differentiation in response to local environmental conditions is a key component of species adaptation and persistence. Understanding the structuring of phenotypic diversity in response to local environmental pressures can provide important insights into species evolutionary dynamics and responses to environmental change. This work examines the influence of steep environmental gradients on intraspecific phenotypic variation and tests two hypotheses about how the tropical soft grass mouse, Akodon mollis Cricetidae, Rodentia , contends with the disparate environmental conditions encompassed by its broad distribution. Specifically, we test if the species expresses a geographically unstructured, or generalist, phenotype throughout its range or if it shows geographically localized morphological differentiation across disparate environments.

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Background: The extent of phenotypic differentiation in response to local environmental conditions is a key component of species adaptation and persistence. Understanding the structuring of phenotypic diversity in response to local environmental pressures can provide important insights into species evolutionary dynamics and responses to environmental change.

This work examines the influence of steep environmental gradients on intraspecific phenotypic variation and tests two hypotheses about how the tropical soft grass mouse, Akodon mollis Cricetidae, Rodentia , contends with the disparate environmental conditions encompassed by its broad distribution.

Specifically, we test if the species expresses a geographically unstructured, or generalist, phenotype throughout its range or if it shows geographically localized morphological differentiation across disparate environments. Results: Using geometric morphometric and ecomorphological analyses of skull shape variation we found that despite distinct environmental conditions, geographically structured morphological variation is limited, with the notable exception of a distinct morphological disjunction at the high-elevation forest-grassland transition in the southern portion of A.

Based on genetic analyses, geographic isolation alone does not explain this localized phenotype, given that similar levels of genetic differentiation were also observed among individuals inhabiting other ecosystems that are nonetheless not distinct morphologically. Conclusions: Instead of phenotypic specialization across environments in these tropical mountains, there was limited differentiation of skull shape and size across the broad range of A. The high morphological variance among individuals, together with a weak association with local environmental conditions, not only highlights the flexibility of A.

The work also indicates that mechanisms other than processes linked to local ecological specialization as a driver of diversification may contribute to the high diversity of this tropical region. This site needs JavaScript to work properly. Please enable it to take advantage of the complete set of features!

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Full-text links Cite Favorites. Abstract Background: The extent of phenotypic differentiation in response to local environmental conditions is a key component of species adaptation and persistence.

Figures Figure 1 5 Ecosystem map of northwestern Peru…. Figure 1 13 Ecosystem map of northwestern Peru indicating the location of samples. The inset map…. Ecosystem map of northwestern Peru indicating the location of samples. The inset map on the bottom right corner shows the position of Peru in grey and of the study region in black within South America.

Pictures of the habitats of four of the localities their location indicated by the numbers on the map, which follow the numbering of the pictures are also included to show the abrupt transition between habitats along the altitudinal range of A. These grasslands are characterized by high atmospheric humidity, high rainfall, and a continuous layer of short vegetation, dwarf shrubs, and wetlands []. On the central-south and southwest Peruvian Andes, this abrupt transition occurs between the xeric habitats characteristic of this region and a short forest dominated by quenoa trees Polylepis spp.

Figure 2 5 Skull size and shape variability…. Figure 2 13 Skull size and shape variability in A. Scatterplots of all sampled…. Skull size and shape variability in A. Scatterplots of all sampled individuals according to their centroid size a and their scores on the first two between-groups principal components BG-PCA of uncorrected b and size-corrected shape c see Methods for details.

Individuals from the highest ecosystem i. In addition, in order to illustrate the amount of intrapopulation variance, the position of individuals from two arbitrarily selected populations are highlighted in blue and red populations 9 and 14, respectively; see Appendix as an example in an inset in each plot.

Figure 3 5 Morphological-environmental association recovered in the…. Figure 3 13 Morphological-environmental association recovered in the PLS analyses. Scatterplots of the single set of…. Morphological-environmental association recovered in the PLS analyses. Scatterplots of the single set of PLS axes for the analysis on size a , and the first b and second c set of PLS axes for the analysis on uncorrected shape results for the size-corrected shape data were similar; not shown.

Although PLS analyses were run on population-averaged data, the extent of local intra-population variability is depicted as vertical lines below and above each population score, with the line lengths determined by the minimum and maximum individual scores obtained for each population when all individuals are projected onto each morphological PLS component.

In d the morphological changes associated with the PLS axes shown in b and c are summarized by comparing the skull regions associated with each PLS in black with the overall mean shape of the entire sample in grey. Figure 4 5 Relative explanatory power of environmental…. Result of spatial regressions….

Relative explanatory power of environmental variation in SEVM regressions. Result of spatial regressions of size and uncorrected u. The proportion of variance explained exclusively by each set of predictors as well as the shared explained variance i.

The total variance explained is given on top of each bar. Note that in the shape analyses, the data depicted correspond to the overall variance explained i. Figure 5 5 Morphological and genetic spatial isolation. Figure 5 13 Morphological and genetic spatial isolation. Scatterplot of pairwise morphological a and genetic b …. Morphological and genetic spatial isolation. Scatterplot of pairwise morphological a and genetic b distance against pairwise geographic distance between populations.

Points are colored according to which ecosystem the populations being compared pertain i. The correlation coefficient and significance of both morphological and genetic trends are presented above each scatterplot. Figure 6 5 Landmarks used to characterize the….

Figure 6 13 Landmarks used to characterize the ventral skull of A. Landmark description is…. Landmarks used to characterize the ventral skull of A. See this image and copyright information in PMC. Chiaverano LM, et al. PLoS One. Divergent selection along elevational gradients promotes genetic and phenotypic disparities among small mammal populations. Ecol Evol. The role of environment and core-margin effects on range-wide phenotypic variation in a montane grasshopper.

Noguerales V, et al. J Evol Biol. Epub Jun PMID: The spatial and temporal distributions of arthropods in forest canopies: uniting disparate patterns with hypotheses for specialisation. Wardhaugh CW. Biol Rev Camb Philos Soc. Epub Mar 2.

PMID: Review. Fitness of multidimensional phenotypes in dynamic adaptive landscapes. Laughlin DC, Messier J. Laughlin DC, et al. Trends Ecol Evol. Show more similar articles See all similar articles.

Niche suitability affects development: skull asymmetry increases in less suitable areas.

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Akodon mollis

We'd like to understand how you use our websites in order to improve them. Register your interest. The morphology, G- and C-banding pattern of the Akodon mollis chromosome complement is analysed. Over a total of 14 males and 10 females studied, 8 males and 7 females had a modal chromosome number of 22, while 6 males and 3 females showed a modal number of 23 chromosomes.

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JavaScript is disabled for your browser. Some features of this site may not work without it. Abstract: The mechanisms responsible for the species composition of montane biotas remain poorly understood. Parapatric and allopatric speciation, in the forms of the Ecological Gradients and Montane Vicariance hypotheses respectively, have been suggested to explain the diversification of Andean fauna. This dissertation reviews the possible role of these mechanisms in the speciation of mammals in Andean habitats. The soft grass mouse, Akodon mollis, was chosen as the test organism because of its wide elevational and latitudinal range. Partial least squares and multivariate multiple regression analyses showed a significant association between skull shape and environment.

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