14 research outputs found
How has the environment shaped geographical patterns of insect body sizes? A test of hypotheses using sphingid moths
Aim: We mapped the geographical pattern of body sizes in sphingid moths and investigated
latitudinal clines. We tested hypotheses concerning their possible environmental
control, that is, effects of temperature (negative: temperature size rule or
Bergmann's rule; positive: converse Bergmann rule), food availability, robustness to
starvation during extreme weather and seasonality.
Location: Old World and Australia/Pacific region.
Methods: Body size data of 950 sphingid species were compiled and related to their
distribution maps. Focusing on body length, we mapped the median and maximum
size of all species occurring in 100 km grid cells. In a comparative approach, we tested
the predictions from explanatory hypotheses by correlating species' size to the average
environmental conditions encountered throughout their range, under univariate
and multivariate models. We accounted for phylogeny by stepwise inclusion of phylogenetically
informed taxonomic classifications into hierarchical randomâintercept
mixed models.
Results: Median body sizes showed a distinctive geographical pattern, with large species
in the Middle East and the Asian tropics, and smaller species in temperate regions
and the Afrotropics. Absolute latitude explained very little body size variation,
but there was a latitudinal cline of maximum size. Species' median size was correlated
with net primary productivity, supporting the food availability hypothesis, whereas
support for other hypotheses was weak. Environmental correlations contributed
much less (i.e. <10%) to explaining overall size variation than phylogeny (inclusion of
which led to models explaining >70% of variability).
Main conclusion: The intuitive impression of larger species in the tropics is shaped by
larger size maxima. Median body sizes are only very weakly related to latitude. Most
of the geographical variation in body size in sphingid moths is explained by their phylogenetic
past. NPP and forest cover correlate positively with the body size, which
supports the idea that food availability allowed the evolution of larger sizes.The attached document is the author(âsâ) final accepted/submitted version of the journal article. You are advised to consult the publisherâs version if you wish to cite from i
Distribution patterns of riodinid butterflies (Lepidoptera: Riodinidae) from southern Brazil
Background: The aim of this study was to synthesize the knowledge of Riodinidae butterflies (Lepidoptera: Papilionoidea) in Rio Grande do Sul state (RS), southern Brazil, evaluating the role of climatic, topographic, and vegetational variables on the observed patterns of occurrence and distribution of these butterflies in the Pampa and Atlantic Forest biomes. The records of riodinid butterflies in RS were collected from published studies and the examination of museum collections in Brazil. Results: A total of 97 taxa of Riodinidae were recorded, distributed in 92 municipalities. The NMDS analysis and the Constrained Analysis of Principal Coordinates grouped the municipalities according to the phytogeographic regions and biomes - Pampa and Atlantic Forest domains - in which the species records were made. Distance from the ocean, precipitation and temperature were the environmental variables which most contributed to explain the distribution patterns of these butterflies. The multivariate Mantel correlogram suggests that over short distances, the composition of species shows significant levels of spatial autocorrelation, and as geographic distance increases, these levels tend to present negative values. Conclusions: The results suggest that the observed distribution pattern of Riodinidae in the different biomes and phytogeographic regions in the extreme southern Brazil could be explained by climatic, environmental variables and geographic distance
Environmental impact of tsetse eradication in Senegal
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