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961.
DAVID TARKHNISHVILI ALEXANDER GAVASHELISHVILI LEVAN MUMLADZE 《Biological journal of the Linnean Society. Linnean Society of London》2012,105(1):231-248
Spatial and temporal constraints on dispersal explain the absence of species from areas with potentially suitable conditions. Previous studies have shown that post‐glacial recolonization has shaped the current ranges of many species, yet it is not completely clear to what extent interspecific differences in range size depend on different dispersal rates. The inferred boundaries of glacial refugia are difficult to validate, and may bias spatial distribution models (SDMs) that consider post‐glacial dispersal constraints. We predicted the current distribution of 12 Caucasian forest plants and animals, factoring in the effective geographical distance from inferred glacial refugia as an additional predictor. To infer glacial refugia, we tested the transferability of the current SDMs based on the distribution of climatic variables, and projected the most transferable ones onto two climate scenarios simulated for the Last Glacial Maximum (LGM). We then calculated least‐cost distances from the inferred refugia, using elevation as a friction surface, and recalculated the current SDMs incorporating the distances as an additional variable. We compared the predictive powers of the initial with the final SDMs. The palaeoclimatic simulation that best matched the distribution of species was assumed to represent the closest fit to the true palaeoclimate. SDMs incorporating refugial distance performed significantly better for all but one studied species, and the Model for Interdisciplinary Research on Climate (MIROC) climatic simulation provided a more convincing pattern of the LGM climate than the Community Climate System Model (CCSM) simulation. Our results suggest that the projection of suitable habitat models onto past climatic conditions may yield realistic boundaries of glacial refugia, and that the current distribution of forest species in the study region is strongly associated with locations of former refugia. We inferred six major forest refugia throughout western Asia: (1) Colchis; (2) western Anatolia; (3) western Taurus; (4) the upper reaches of the Tigris River; (5) the Levant; and (6) the southern Caspian basin. The boundaries of the modelled refugia were substantially broader than the refugia boundaries inferred solely from pollen records. Thus, our method could be used to: (1) improve models of current species distributions by considering the dispersal histories of the species; and (2) validate alternative reconstructions of palaeoclimate with current distribution data. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 231–248. 相似文献
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The carbon (δ(13) C) and nitrogen (δ(15) N) values of Sander vitreus scales differed pre and post-introduction in treatment lakes among years following the introduction of Micropterus dolomieu. No difference of δ(13) C and δ(15) N in S. vitreus scales was found in control lakes where M. dolomieu were not introduced. In treatment lakes, S. vitreus δ(15) N increased and δ(13) C decreased. No relationship was found between S. vitreus and M. dolomieu abundance in the two treatment lakes. Size structure of S. vitreus and M. dolomieu was negatively correlated and condition of the two species was positively correlated. Although S. vitreus feeding habits may have changed in the treatment lakes after M. dolomieu introductions, evidence suggests that fitness-related factors (i.e. abundance and condition) of S. vitreus remained unchanged, indicating S. vitreus and M. dolomieu may coexist where M. dolomieu have been introduced. 相似文献
966.
Factors affecting the occurrence of postpartum prolonged luteal activity in clinically healthy high-producing dairy cows 总被引:1,自引:0,他引:1
The objective was to characterize risk factors affecting the occurrence of prolonged luteal phase (PLP) in postpartum, clinically healthy, high-producing dairy cows. Transrectal ultrasound examinations of the reproductive tract were performed twice weekly, from the 1st to 8th wk after calving in 151 multiparous clinically healthy lactating Holstein cows (mean ± SD of peak milk yield = 56.7 ± 7.4 kg). Serum samples were collected twice weekly to measure progesterone and every 2 wk to detect β-hydroxybutyrate (βHB), and α1-acid glycoprotein (AGP). Body condition score (BCS) was recorded weekly after calving. Based on the serum progesterone profile, 52 (34.4%) cows had normal ovarian activity (NLA), whereas 36 (23.8%) cows had a prolonged luteal phase (PLP), the most prevalent type of abnormal pattern of luteal activity. Furthermore, 63 cows with short luteal activity, delayed first ovulation, or cystic ovaries were excluded from this study. Serum AGP concentrations, as an indication of postpartum chronic endometritis, were not different (P > 0.05) between cows with NLA and PLP. Categories of peak milk yields (kg) were positively correlated with the incidence (%) of cows with PLP (r = 0.87, P = 0.02). Furthermore, milk yield peak, day of milk yield peak, mean milk yield (8 wk in milk), and milk yield on the expected day of luteolysis were higher (P < 0.05) in cows with PLP than NLA, and cows with PLP had greater loss of BCS (P = 0.007) than those with NLA. The likelihood of cows with PLP decreased by 0.9-fold for every 1 d delay of commencement of luteal activity (C-LA). Moreover, the likelihood of cows with PLP increased by 1.8-fold for each 1 mmol/L increase in the 1st wk serum βHB concentrations. In conclusion, higher mean of milk yield, greater BCS loss, earlier C-LA, and later peak milk yield were the major risk factors affecting the occurrence of postpartum PLP in clinically healthy, high-producing dairy cows. 相似文献
967.
David Sánchez‐Fernández Jorge M. Lobo Andrés Millán Ignacio Ribera 《Global Ecology and Biogeography》2012,21(10):988-997
Aim The contrasting habitat permanence over geological time‐scales of lotic and lentic habitats may impose different constraints on the dispersal ability of their macroinvertebrate populations, and ultimately on the degree of equilibrium with current climate. We aim to test for differences between species typical of either habitat type in their potential versus realized distributions as a surrogate measure of degree of climate equilibrium, both in refuges and more recently deglaciated areas. Location Western Europe. Methods We focus on 99 Iberian diving beetles (family Dytiscidae). A multidimensional envelope procedure was used to estimate their potential distributions, which were projected for different spatial scales. At the continental scale we calculated the percentage of countries with climatically suitable conditions for each species over those actually occupied (range filling). At the regional scale, we estimated realized distributions using: (1) convex hull polygons for Sweden and the Iberian Peninsula; and (2) generalized linear models for the Iberian Peninsula. Results In the Iberian Peninsula, differences in the degree of equilibrium with climatic conditions between lotic and lentic species were few, if any. However, at the continental scale we found significant differences, with lentic species closer to equilibrium than lotic species. In the recently deglaciated area (Sweden) the subset of species with ranges wide enough to encompass Iberia and Scandinavia were mostly lentic, and all were closer to climatic equilibrium without significant differences between habitat types. Main conclusions Our results show that, at continental scales, climate equilibrium is not concordant between the habitat types across western Europe. We hypothesize that: (1) the differences between refuge areas in dispersal ability are erased probably due to long‐term climatic stability, allowing enough time to reach equilibrium, and (2) the species with wide geographical ranges able to recolonize recently deglaciated areas should have the highest dispersal abilities, and are closer to climatic equilibrium. 相似文献
968.
Andrés Baselga Jorge M. Lobo Jens‐Christian Svenning Pedro Aragón Miguel B. Araújo 《Global Ecology and Biogeography》2012,21(11):1106-1113
Aim A debate exists as to whether present‐day diversity gradients are governed by current environmental conditions or by changes in environmental conditions through time. Recent studies have shown that latitudinal richness gradients might be partially caused by incomplete post‐glacial recolonization of high‐latitude regions; this leads to the prediction that less mobile taxa should have steeper gradients than more mobile taxa. The aim of this study is to test this prediction. Location Europe. Methods We first assessed whether spatial turnover in species composition is a good surrogate for dispersal ability by measuring the proportion of wingless species in 19 European beetle clades and relating this value to spatial turnover (βsim) of the clade. We then linearly regressed βsim values of 21 taxa against the slope of their respective diversity gradients. Results A strong relationship exists between the proportion of wingless species and βsim, and βsim was found to be a good predictor of latitudinal richness gradients. Main conclusions Results are consistent with the prediction that poor dispersers have steeper richness gradients than good dispersers, supporting the view that current beetle diversity gradients in Europe are affected by post‐glacial dispersal lags. 相似文献
969.
Robalo JI Castilho R Francisco SM Almada F Knutsen H Jorde PE Pereira AM Almada VC 《Ecology and evolution》2012,2(1):153-164
Pleistocene climate changes have imposed extreme conditions to intertidal rocky marine communities, forcing many species to significant range shifts in their geographical distributions. Phylogeographic analyses based on both mitochondrial and nuclear genetic markers provide a useful approach to unravel phylogeographic patterns and processes of species after this time period, to gain general knowledge of how climatic changes affect shifts in species distributions. We analyzed these patterns on the corkwing wrasse (Symphodus melops, Labridae), a rocky shore species inhabiting North Sea waters and temperate northeastern Atlantic Ocean from Norway to Morocco including the Azores, using a fragment of the mitochondrial control region and the first intron of the nuclear S7 ribosomal protein gene. We found that S. melops shows a clear differentiation between the Atlantic and the Scandinavian populations and a sharp contrast in the genetic diversity, high in the south and low in the north. Within each of these main geographic areas there is little or no genetic differentiation. The species may have persisted throughout the last glacial maximum in the southern areas as paleotemperatures were not lower than they are today in North Scandinavia. The North Sea recolonization most likely took place during the current interglacial and is dominated by a haplotype absent from the south of the study area, but present in Plymouth and Belfast. The possibility of a glacial refugium in or near the English Channel is discussed. 相似文献
970.
Deniz Haydar 《Diversity & distributions》2012,18(2):101-110
Aim Cryptogenic species may include those taxa that were historically introduced and are now falsely viewed as native. Investigated here is the scale of cryptogenesis in the North Atlantic Ocean by examining disjunct distributions, defined as temperate species occurring only on both sides of the North Atlantic. Disjunct distributions can be explained by four scenarios: glacial relicts, taxonomic artefacts, natural trans‐oceanic dispersal and human‐mediated introduction. Location North Atlantic Ocean. Methods Model taxa included ascidians, bivalves and hydrozoans. Biogeographic status (native, introduced or cryptogenic) was assigned to all species exhibiting a disjunct distribution, based upon multiple criteria. Results Of 1030 species, 60 have a strictly disjunct distribution. Of these disjunct species, for five species there is no reason to doubt their native status, and 55 species are cryptogenic or introduced. Groups with high relative dispersal capacities do not have disjunct distributions more often. Infaunal bivalves have the lowest relative number of disjunct species; none are cryptogenic or naturally disjunct. This supports the concept that glaciations are unlikely to cause disjunct distributions: there are no studies that provide conclusive evidence for the glacial relict model. Hydrozoa have the highest relative number of disjunct species, which, while historically explained by undocumented rafting, may more likely be the result of dispersal by ships, which travel relatively fast, are independent of currents and provide greater surface area. Main conclusions This reanalysis of the historical biogeography of the North Atlantic marine biota reveals that far more species may have been introduced than previously recognized, potentially significantly altering our fundamental understanding of community evolution and ecology. Species that have been present for centuries and can be important ecological engineers who have shaped contemporary communities are possibly falsely viewed as native: they may in fact be the unrecognized introductions of historical times. 相似文献