The genetic basis of high-latitude adaptation in wild soybean

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Thermal tolerance and geographical range size in the Agabus brunneus group of European diving beetles (Coleoptera: Dytiscidae)

Aim Within clades, most taxa are rare, whilst few are common, a general pattern for which the causes remain poorly understood. Here we investigate the relationship between thermal performance (tolerance and acclimation ability) and the size of a species’ geographical range for an assemblage of four ecologically similar European diving beetles (the Agabus brunneus group) to examine whether thermal physiology relates to latitudinal range extent, and whether Brown’s hypothesis and the environmental variability hypothesis apply to these taxa. Location Europe. Methods In order to determine the species tolerances to either low or high temperatures we measured the lethal thermal limits of adults, previously acclimated at one of two temperatures, by means of thermal ramping experiments (± 1°C min^?1). These measures of upper and lower thermal tolerances (UTT and LTT respectively) were then used to estimate each species’ thermal tolerance range, as total thermal tolerance polygons and marginal UTT and LTT thermal polygons. Results Overall, widespread species have higher UTTs and lower LTTs than restricted ones. Mean upper lethal limits of the Agabus brunneus group (43 to 46°C), are similar to those of insects living at similar latitudes, whilst mean lower lethal limits (?6 to ?9°C) are relatively high, suggesting that this group is not particularly cold‐hardy compared with other mid‐temperate‐latitude insects. Widespread species possess the largest thermal tolerance ranges and have a relatively symmetrical tolerance to both high and low temperatures, when compared with range‐restricted relatives. Over the temperature range employed, adults did not acclimate to either high or low temperatures, contrasting with many insect groups, and suggesting that physiological plasticity has a limited role in shaping distribution. Main conclusions Absolute thermal niche appears to be a good predictor of latitudinal range, supporting both Brown’s hypothesis and the environmental variability hypothesis. Restricted‐range species may be more susceptible to the direct effect of climate change than widespread species, notwithstanding the possibility that even ‘thermally‐hardy’, widespread species may be influenced by the indirect effects of climate change such as reduction in habitat availability in Mediterranean areas.     

EVOLUTION OF INTRINSIC GROWTH AND ENERGY ACQUISITION RATES. I. TRADE-OFFS WITH SWIMMING PERFORMANCE IN MENIDIA MENIDIA

Abstract Latitudinal populations of the Atlantic silverside, Menidia menidia , show substantial genetic variation in rates of energy acquistion and allocation. Reared in common environments, silversides from northern latitudes consume more food, grow faster and more efficiently, store more energy, and produce greater quantities of eggs than their southern conspecifics. The persistence of seemingly inferior southern genotypes in the face of ostensibly superior northern genotypes suggest that there are hidden evolutionary trade-offs associated with these elevated acquisition and allocation rates. We tested the hypothesis that rapid growth and high levels of food consumption trade-off against locomotory performance in M. menidia . We compared both aerobic (prolonged and endurance) and anaerobic (burst) swimming capacities between intrinsically fast-growing fish from the north (Nova Scotia, NS) and intrinsically slow-growing fish from the south (South Carolina, SC) and between growth-manipulated phenotypes within each population. We also compared swimming speeds and endurance between fasted and recently fed fish within populations. Maximum prolonged and burst swimming speeds of NS fish were significantly lower than those of SC fish, and swimming speeds of fast-growing phenotypes were lower than those of slow-growing phenotypes within populations. Fed fish had lower burst speeds and less endurance than fasted fish from the same population. Thus, high rates of growth and the consumption of large meals clearly diminish swimming performance, which likely increases vulnerability to predation and decreases survival and relative fitness. The submaximal growth rate of southern M. menidia appears to be adaptive, resulting from balancing selection on rates of somatic growth.     

Geographical variability in, and temperature effects on, the phenology of Maniola jurtina and Pyronia tithonus (Lepidoptera, Satyrinae) in England and Wales

ABSTRACT. 1. Geographical variability in, and temperature effects on, the mean date of adult flight period and the SD about this date are analysed for two univoltine, grassland butterflies in England and Wales from 1976 to 1985. Data were collected on the Butterfly Monitoring Scheme for Maniola jurtina (L.) at twenty-nine sites and Pyronia tithonus (L.) at twenty sites.
2. Substantial variability for mean date and SD occurs between years and between sites. Changes in mean date between years tend to occur consistently at different sites. The species show some parallel in variation between sites, especially for mean date.
3. June maximum temperature accounts for 95% and 75% of the variation in mean date between years in M. jurtina and P. tithonus , respectively ( r =-0.97 and -0.87). Similar relationships occur for temperatures cumulated over the period of post-winter development from March to July or August.
4. Greater geographical variability in phenology, and a generally less synchronized flight period in M.jurtina may be associated with broader habitat preferences than in P. tithonus.
5. The mean date of adult flight period remains at roughly the same date at more northerly latitudes. In M.jurtina the flight period becomes more synchronized, begins later and ends earlier in the north. P. tithonus shows little or no indication of such a response to latitude. This is discussed with regard to changes in season length and factors limiting the species'range.     

Traits shaping urban tolerance in birds differ around the world

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